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• Grassland biomass allocation is sensitive to natural conditions and grazing practices. • Differences in grassland biomass allocation existed among continents. • Grazing practice affected aboveground part and the ratio of it to below-ground part. • Climate has a stronger role in regulating grassland biomass allocation than altitude. • Warming may exert a more detrimental effect on grazed grasslands than non-grazed ones. Biomass allocation in grasslands is key to understanding plant response to environmental changes and grazing management. Yet, global studies on how this split between above-ground and below-ground biomass varies across continents and grazing practices are notably scarce. We employ a comprehensive field-oriented grassland database to examine differences in total net primary productivity (TNPP), above-ground net primary productivity (ANPP), below-ground net primary productivity (BNPP), and the BNPP to ANPP ratio across continents and between grazed and non-grazed grasslands. Oceania showed the greatest ANPP (916 g·m−2·a−1), while Asia had the lowest (192 g·m−2·a−1). BNPP values were similar among Oceania, Africa, and Asia (∼600 g·m−2·a−1), significantly exceeding those in Europe (289 g·m−2·a−1) and North America (408 g·m−2·a−1). South America, Africa, and Oceania had the highest TNPP (around 1418 g·m−2·a−1 to 1466 g·m−2·a−1), while Europe had the lowest TNPP (344 g·m−2·a−1). The BNPP to ANPP ratio was highest in South America (4.17) and Asia (3.46). Global differences in TNPP and BNPP between grazed and non-grazed grasslands were minimal, but ANPP (169 g·m−2·a−1 and 198 g·m−2·a−1, respectively) and the BNPP to ANPP ratio (4.87 and 2.40, respectively) differed significantly. Across continents and grazing practices, climate had a greater role in regulating grassland biomass allocation than altitude, and warming may have a more detrimental impact on grazed grasslands than non-grazed grasslands. Distinct biomass allocation trends under various continental and grazing conditions exert effects on the economic and ecological functions of grasslands. Our study underscores the need for balanced grassland utilization strategies at a global scale. This involves optimizing grazing in high ANPP grasslands and protecting those with significant BNPP, thereby contributing to a sustainable and ecologically sound use of grasslands in the future. [ABSTRACT FROM AUTHOR]

Increasing concentration of ground level O 3 and its negative impacts on agricultural output is well documented, however, the response of leguminous crop plants is still sparsely cited. Given their nutritional richness, legume seeds are widely esteemed as a crucial dietary staple worldwide, prized for their abundance of oil, protein, dietary fiber, and low-fat characteristics. Termed as the "poor man's meat" due to their high-quality protein, they hold immense economic value. Acknowledging the significance of legumes, a field experiment was conducted to understand the physiological and antioxidant responses, stomatal characteristics, and yield response in three cultivars of Pisum sativum L. (K Agaiti, K Uday and K Damini), exposed to elevated ozone (O 3). In the present study, Pisum sativum cultivars were subjected to ambient (control) and elevated (+15 ppb) concentrations of O 3 , using separate sets of OTCs. Elevated O 3 stimulated the activity of the enzymes of Halliwell Asada pathway, which were responsible for the differential response of the three experimental cultivars. While K Agaiti and K Uday focused on upregulating their antioxidant defense, K Damini followed the strategy of biomass allocation. Test weight showed that K Damini was most efficient in succoring the yield losses under elevated O 3. Under elevated O 3 , test weight reduced by 8.91%, 7.52%, and 5.1%, respectively, in K Agaiti, followed by K Uday and K Damini, rendering K Agaiti most sensitive to O 3 stress. The present study not only helps us to elucidate the O 3 sensitivity of the selected experimental cultivars, it also helps us in screening O 3 tolerant cultivars for future agricultural practices. [Display omitted] • The manuscript defines the O 3 sensitivity of the selected pea cultivars. • O 3 flux encompasses the differential mechanistic responses among the selected pea cultivars. • Yield response of the different pea cultivars is not correlated with their respective O 3 flux. [ABSTRACT FROM AUTHOR]

Climate change modifies the dynamics and the quantity of plant water supply, and plant morphological response to environmental factors plays a key role in crop-weed interactions. This study investigated the interspecies diversity related to the morphological responses of annual herbaceous species to water stress. Key morphological traits were measured at two growth stages on five weed and two crop (soft wheat, rapeseed) species grown on a gradient of water availability in a greenhouse experiment. For each trait, response curves to water stress were defined, and their parameters were used to quantify interspecies diversity. Generic morphological response patterns were identified across all species and plant stages. Water stress reduced leaf area per unit leaf biomass (SLA, lowering water demand) and increased the ratio of plant height to aboveground biomass for all species (HBR, keeping access to light). In most situations, the ratio of root biomass over total biomass (RBR) increased (improving water uptake). Variability in parameter values of morphological traits was primarily explained by the species, followed by growth stage. Geranium dissectum L. and Abutilon theophrasti Medik. were the most responsive species to water stress, especially at the flowering stage, with strong RBR and HBR increase and slight SLA decrease. Species differences were not related to clade (monocotyledonous/dicotyledonous) nor status (weed/crop), despite a near-significant clade effect on allocation of aboveground biomass, with grass species allocating more biomass to stems (vs leaves), while no general tendency was observed in broadleaved species. These findings provide new insights on comparative ecology of weed and crop species response to water limitation, and more research is expected to cover a wider range of weed and crop species. • Generic morphological responses were identified across species and stages. • Water-stressed plants adapt morphology to lower demand and raise uptake efficiency. • Water stress lowered specific leaf area and enhanced root biomass allocation. • Morphological response to water stress varied more among species than between stages. • Interspecies diversity was neither clade- nor crop/weed-dependent. [ABSTRACT FROM AUTHOR]

The mycorrhizal growth response (MGR), defined as the biomass difference between a mycorrhizal plant and a non-mycorrhizal plant of the same species, varies with soil nutrient availability, fungal taxa, and host plant functional group. However, how MGR reacts to changes in arbuscular mycorrhizal fungus (AMF) richness is still not well understood. To assess how AMF richness affected MGR in different organs of plants and discover how MGR varied with plant functional groups, we collected 72 published papers that concurrently studied single and mixed inocula treatments in two common plant functional groups: woody and herbaceous plants. We then compiled a dataset of mycorrhizal colonization rate (MC), MGR of root biomass (MGRr), MGR of shoot biomass (MGRs), MGR of total biomass (MGRt), and root-to-shoot ratio (MGRr/s) for single, dual, and multiple inocula at the fungus and plant species levels. Variation of MGR parameters and MC along inoculum richness generally showed similar patterns at the fungus and plant species levels in both woody and herbaceous plants, respectively. MC tended to increase from single to multiple inocula in the two plant functional groups. MGRs, MGRr, and MGRt tended to increase with increasing inoculum richness in woody plants, but not in herbaceous plants, with nearly 2-fold increments between single and multiple inocula. MGRr/s was generally stable in both woody and herbaceous plants. In general, MC and MGR parameters, except for MGRr/s, were higher in woody plants than in herbaceous plants with the same inoculum richness. The strong positive effect of inoculum richness on MGR parameters in woody plants can be explained by the close relationships between MGR and MC, and between MGR and inoculum richness. Conversely, in herbaceous plants, the associations were weak between MGR parameters and MC or inoculum richness. Our results suggest that multiple inocula generally had a stronger positive impact on MGR parameters than single and dual inocula, and this effect was more prominent in woody plants than in herbaceous plants. These findings not only deepen the understanding of the interaction between AMF richness and host plant growth but also provide insights into the application and development of AMF fertilizer in agriculture and forestry. [Display omitted] ● Multiple inocula generally have a stronger positive impact on MGR parameters. ● Effects of multiple inocula is more prominent in woody plants than in herbs. ● Species and family richness of AMF is the key to the strength of inoculum effect. [ABSTRACT FROM AUTHOR]

Elevated CO 2 concentrations may inhibit photosynthesis due to nitrogen deficiency, but legumes may be able to overcome this limitation and continue to grow. Our study confirms this conjecture well. First, we placed the two-year-old potted saplings of Ormosia hosiei (O. hosiei) (a leguminous tree species) in the open-top chamber (OTC) with three CO 2 concentrations of 400 (CK), 600 (E1), and 800 μmol·mol−1 (E2) to simulate the elevated CO 2 concentration environment. After 146 days, the light saturation point (LSP), light compensation point (LCP), apparent quantum efficiency (AQE), and dark respiration rate (Rd) of O. hosiei were increased under increasing CO 2 concentration and obtain the maximum ribulose diphosphate (RuBP) carboxylation rate (V c max) and RuBP regenerated photosynthetic electron transfer rate (J max) were also significantly increased under E2 treatment (P < 0.05). This results in a significant increase of the maximum assimilation rate (A max) under elevated CO 2 concentrations. Sucrose phosphate synthase (SPS) activity in sucrose metabolism increased in the leaves, more soluble sugars, starches, and sucrose was produced, but sucrose content only in leaves increased at E2, and more carbon flows to the roots. The activity of the NH 4 + assimilating enzymes glutamine synthetase (GS), glutamate synthetase (GOGAT), and glutamate dehydrogenase (GDH) in the leaves of O. hosiei increases under elevated CO 2 concentrations to promote nitrogen synthesis that reduces the content of ammonium nitrogen and increases the content of nitrate nitrogen. In addition, under E1 conditions, sucrose synthase (SS), direction of synthesis activity was highest and sucrose invertase (INV) activity was lowest, this means that the balance of C and N metabolism is maintained. While under E2 conditions SS activity decreased and INV activity increased, this increased C/N and nitrogen use efficiency. So, the elevated CO 2 concentration promotes the accumulation of O. hosiei biomass, especially in the aboveground part, but did not have a significant effect on the accumulation of root biomass. This means that O. hosiei is able to cope under the elevated CO 2 concentration without showing photosynthetic adaptation during the experimental period. • The legume of O.hoeisi did not show photosynthetic adaptation under elevated CO 2 concentration. • In elevated CO 2 environment, O.horeisi 's strong C input promoted nodule nitrogen fixation. • Elevated CO 2 concentration was beneficial to the biomass accumulation of O.houeisi , especially the aboveground part. [ABSTRACT FROM AUTHOR]

Increasing maize planting density is a major agronomic practice to enhance population grain yield, however, canopy shadowing at high density limits plant growth and per-plant grain yield. Dry mass (DM) accumulation, allocation, and remobilization are crucial factors determining grain yield. However, there is limited understanding regarding these processes in response to increasing planting density. This study aimed to evaluate how planting density affects DM accumulation, allocation, and remobilization, as affected by plant architecture, nitrogen (N) rates, N fertilization frequency, and water management. A meta-analysis was conducted, involving 2363 observations from 253 peer-reviewed studies. Globally, population grain yield increased by 11.2 %, which was attributable to increases in a population pre-silking DM (PrS-DM) accumulation of 22.9 % and remobilization efficiency of 12.6 %. Temporally, under a high planting density, per plant DM production showed a decrease (8.3–16.0 %) during the pre-silking stage, but a greater reduction (24.0–25.4 %) during the post-silking stage. DM allocation to roots was greatly reduced, with a decline of 22.1–25.1 % in the root-to-shoot ratio (R/S), and a dropping rate of 5.2 % in harvest index (HI). Compact plant architecture showed a 12.2 % increase in grain yield and a reduction of 3.4 % in HI. Appropriate N rates coupled with splitting-N applications showed an increase in grain yield (up to 13.9 %) and PrS-DM (up to 27.1 %), but a decline in post-silking DM (PoS-DM) (up to 9.7 %) and HI (up to 9.0 %). Efficient water management, i.e., fertigation increased the grain yield (up to 16.9 %). Increasing planting density increases grain yield mainly by efficiently utilizing light resources during the vegetative stage to increase population PrS-DM production and its remobilization to grain. In addition, less biomass is allocated to the root so that more assimilation is used for shoot growth. Field management practices and breeding efforts should focus on facilitating early plant growth to increase population PrS-DM accumulation and developing sound root systems to increase efficiency and canopy-lodging resistance. Scheme of impacts of increasing planting density on dynamic shoot and root growth per plant (a, b) and per hectare (c, d) in maize during the whole growth period. Numbers in black indicate the ratio of indicators under high planting density (HD) to that of the farmers' practice (FP, control) respectively. Numbers in red and blue colors indicate the ratio of the dry mass under high planting density to that of the control in shoot and root respectively. Numbers with and without underlines indicate the ratio of indicators under high planting density to that of the control in per-hectare and per-plant level respectively. All the data are pooled for the analysis. HI means harvest index; R/S-R1, R/S-R3, and R/S-R6 indicate root-to-shoot ratio at silking, milk, and maturity stage, respectively. DMRE means remobilization efficiency of dry mass within vegetative tissues. DMRC means the contribution of dry mass remobilization to grain yield. [Display omitted] • Globally, an average 57.8 % increase in planting density led to an 11.2 % increase in grain yield. • The increase in yield was supported by greater pre-silking biomass production and remobilization. • Individual biomass was less affected by high density before silking than that during post-silking. • High density displayed less biomass allocation to root and kernel. • This study brings insights into high-density planting by optimizing breeding and field management. [ABSTRACT FROM AUTHOR]

• Leaf mass-based photosynthetic rate was more enhanced in evergreen trees with eCO2. • Branch hydraulic efficiency was more enhanced in deciduous trees with eCO2. • eCO2 strengthens the coordination of stem hydraulics with leaf gas exchange. Elevated CO 2 concentration (eCO 2) in the atmosphere is expected to impact plant water relations and growth in several ecosystems across the globe. However, we still know little about such impact on tree species in subtropical regions. The present study investigated the impact of eCO 2 on leaf gas exchange, nitrogen and phosphorus concentrations, leaf and stem hydraulic conductivity, and growth of seedlings of four evergreen and four deciduous tree species from a subtropical forest in Southwest China. We found that both evergreen and deciduous tree species at eCO 2 had higher leaf area-based photosynthetic rates and lower leaf stomatal conductance. Further, leaf mass-based photosynthetic rate was more enhanced in evergreen than in deciduous trees at eCO 2. Biomass of evergreen and deciduous species was significantly higher at eCO 2 , with large species-specific variation among the evergreen species. Leaf-specific hydraulic conductivity was more enhanced in deciduous tree species than that of evergreen tree species with eCO 2 , which was mainly driven by the increase of biomass at eCO 2. Interestingly, eCO 2 significantly strengthened the coordination of stem hydraulic conductivity with leaf-gas exchange, leaf phosphorus concentration, and plant biomass across evergreen and deciduous species. These results highlighted greater enhancement of photosynthesis and greater species-specific variation in biomass at eCO 2 for evergreen species compared to deciduous species, and stronger hydraulic-photosynthesis correlations at eCO 2 than at aCO 2 for tree species from subtropical forests. The present study provides important insights on the potential impacts of eCO 2 on plant eco-physiology, growth and forest succession in a subtropical forest under global climate change. [ABSTRACT FROM AUTHOR]

Root growth patterns respond to small-scale resource heterogeneity and the presence of roots of neighboring plants, but how a plant integrates its responses to these cues is not well understood. In the presence of neighbors, plants may shift allocation to roots as a consequence of plant size and root:shoot allometry, as a response to resource depletion by neighbors, or through a direct response to neighbor presence. The same response pathways also have the potential to alter proliferation in resource-rich patches in soil. Four species of grassland plants were grown in the greenhouse as single plants, monocultures, and mixtures. Root length allocation as a function of shoot mass was examined for background soil and fertilized patches. Plants grown with same-species neighbors followed the same allometric trajectory as single plants for root length in background soil, so any change in root allocation was due only to reduced plant size. Root proliferation in patches declined with neighbors, consistent with a response to resource depletion. Mixtures overproduced roots in both background soil and in patches, relative to plants of the same size in monocultures. [ABSTRACT FROM AUTHOR]

Gibberellin has been proposed to increase leaf elongation in radish (Raphanus sativus L.) plants, which is associated with decreased tuber growth. Since light intensity can control growth through interaction with gibberellin, investigation of the effect of gibberellin levels on the growth of radish plants would be a step forward towards unraveling factors that underlie biomass accumulation and allocation in response to irradiance levels. Here, we report that the gibberellin biosynthesis inhibitor paclobutrazol (PAC) decreased petiole elongation, but not lamina growth of radish plants grown under full sunlight. However, shading promoted an increase in shoot elongation, while in plants treated with PAC the petiole and leaf lamina fail to elongate. Plants treated with PAC allocated proportionally more biomass to their tubers and less to shoot compared to control under shade. Moreover, PAC decreased the abundance of transcripts encoding cell wall expansion proteins in leaf lamina and petiole of plants grown under shade, which was positively correlated with sugar consumption by the tuber, thereby increasing the mass fraction and concentrations of minerals for tuber. Thus, allocation of biomass during the growth of radish plants and nutritional quality of tubers depend on gibberellin and light intensity. • Paclobutrazol alters radish growth differentially in low- and high-light conditions. • The expression of EXP and XTH genes in shaded leaves is decreased by paclobutrazol. • Paclobutrazol increases mineral concentrations in radish tuber under low irradiance. • Low irradiance and gibberellin contribute to improving the radish tuber yield. [ABSTRACT FROM AUTHOR]

As a key nitrogen (N) source, soil amino acids play an important role in plant N nutrition. However, how amino acids differentially influence the N use strategies of native and invasive plants remains unclear. We performed a potted experiment using five pairs of native and invasive plant congeners, which were subject to 23 N treatments (i.e., 20 protein primary amino acids, nitrate, ammonium, and control), each with 10 replicates. We determined their growth, biomass allocation, N use efficiency, and the growth advantage of plant invaders over their natives. Native and invasive plants used the same 18 amino acid N sources (i.e., a similar amino acid economics spectrum). The growth of plant invaders was invariably better than the growth of native plants, and this superior growth of invaders was linked to their higher root biomass allocation and greater N use efficiency. Additionally, invasive plants had a greater growth advantage on amino acid N than on inorganic N, so was this advantage greater on neutral amino acids than on acidic amino acids. These findings suggest that the differences in amino acid use strategies between invasive and native congeners could help to explain plant invasiveness, as indicated by a growth advantage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Plant biomass allocation in alpine meadows support the optimal allocation hypothesis. • Fencing leads to the allocation of more biomass to roots. • Grazing leads to the allocation of more biomass to shoots. • Grazing encourages the roots of alpine plants to concentrate in the topsoil. • Co-grazing yaks and Tibetan sheep at 1:6 ratio at moderate intensity is preferable. Biomass allocation is a key mechanism for understanding the response of alpine meadow plants to environmental changes. However, the two major theories of plant biomass partitioning, that is, optimal and equidistant allocation, are highly controversial. This study aimed to test these hypotheses by using the biomass allocation pattern of Qinghai–Tibetan Plateau alpine meadows under different herbivore assemblages and enclosures and to identify the key physicochemical factors driving changes in biomass allocation. The results showed that fencing and grazing lead to the allocation of more biomass to roots and shoots, respectively. Additionally, our results support the optimal allocation hypothesis, which is mainly regulated by changes in soil physicochemical properties. Specifically, the trade-off between aboveground- and belowground biomass negatively correlated with the soil bulk density, soil moisture, available nitrogen, and available phosphorus but positively correlated with available potassium. In terms of biomass trade-offs, co-grazing yaks and Tibetan sheep at a 1:6 ratio with moderate grazing intensity may be a reasonable method to use and protect alpine meadows on the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Clonal integration can benefit the performance and fitness of clonal plants in heterogeneous environments. Although trade-offs of sexual and asexual reproduction are key life-history strategies to assess the plant fitness and adaptive abilities, the effects of clonal integration on these is less studied. In this study, a pot experiment was conducted to test how reproductive strategies were affected by clonal integration of clonal plant species Leymus chinensis growing in heterogeneous saline-alkali soils. The results showed that clonal integration had no significant effect on total biomass of whole clone of L. chinensis. The total biomass of younger ramets was higher (+32.8%, P < 0.001) under integration condition, while at the cost of the older ramets (-21.7%, P < 0.001). Moreover, the ratio of ear biomass to clonal growth organs (CGO) biomass was slightly reduced by 31.7% (P = 0.09). For younger ramets, clonal integration enhances biomass allocation towards CGO, while reducing allocation towards ear growth, and the ratio of ear/CGO biomass was significantly reduced by 39.1% (P < 0.01). Results indicated that clonal integration reduced the ratio of ear to clonal growth organ biomass of whole clone, and more biomass was allocated to younger ramets for spatial expansion. Clonal integration influenced reproductive strategies of L. chinensis , while its impact is not depended on nutrient levels or defoliation interference. The study emphasized the significance of clonal integration in promoting the growth of offspring ramets and, consequently, enhancing their abilities to expand rapidly. It could enhance the spatial expansion of L. chinensis on a site scale and provide high potential for restoration of patchy degraded grassland where it is dominant. • Clonal integration improved younger ramets growth at the cost of older ramets. • Clonal integration reduced the ratio of ear to clonal growth organ biomass of whole clone. • Clonal integration affected reproductive allocation regardless of stress/disturbance intensities. • Younger ramets allocated more biomass for expansion under clonal integration conditions. [ABSTRACT FROM AUTHOR]

Maintaining yield stability and food security are significant challenges of our time under a changing climate. Utilizing the carbon fertilization (CF, CO 2 fertilization) effect or organic amendments (OA) application is a vital strategy for improving agricultural productivity in warming. However, there is much uncertainty about whether or how crop biomass accumulation and allocation respond to CF or OA applications under warming conditions. We present a meta-analysis of 828 observations from 88 studies worldwide. We explored single warming (W), warming plus carbon fertilization (WCF), and warming plus organic amendment (WOA) to crop biomass accumulation and allocation effect. Warming (from 0.4 °C to 6 °C) significantly decreases crop yield, total biomass, and harvest index by 9.74 %, 4.53 %, and 7.59 % on average, respectively. The CF was not sufficient to fully compensate for the negative effect of warming on crop yield (-2.50 %, p > 0.05). WOA significantly increased crop yield (4.98 %, p < 0.05) and total biomass (10.33 %, p < 0.05) while not promoting more biomass allocation to seed compared to W. There was a significant increase in yield stability in the WOA treatment, suggesting that transitioning to organic agriculture under warming does not negatively affect yield stability. Apart from warming magnitude, the climate variables (mean annual temperatures and mean annual precipitation), and nitrogen fertilizer supply were the main factors explaining the variation in crop yield with warming, as shown by the sum of Akaike weights analysis. Specifically, warming decreases crop aboveground biomass in tropical climates but promotes biomass trans to seeds. Moreover, greater biomass allocation to seeds was observed in humid environments. These findings indicate that soil moisture increased crop yield and biomass key factors under warming. In summary, OA applications can enhance global food production and security under warming conditions. Our results quantified the yield effects of global-scale warming and assessed the impacts of CF and OA applications under warming conditions on crop yield. The results provided new views for maintaining yield stability and food security under climate warming. • Average warming of 2.11 °C (media = 2 °C) with a mean decrease of 9.74 % in crop yield. • The organic amendment counteracts the negative effect of warming on crop yield. • The cold environment promotes the accumulation of biomass aboveground source organs. • Soil moisture was the key affecting crop yield and biomass. [ABSTRACT FROM AUTHOR]

• Precipitation mainly drives biomass allocation (R/S) in temperate grasslands. • Both precipitation and temperature drive R/S in alpine grasslands. • Plant functional group compositions affect R/S more than soil nutrition. • Effects of forbs on R/S is larger than those other dominant plant groups. Elucidating biomass partitioning between above- and belowground parts in plant communities is vital to better assessing the ecological services of terrestrial ecosystems. However, the knowledge of biomass allocation in grasslands is scant, especially for the divergent mechanisms under both contrasting conditions. On two large geographic transects, Tibetan Plateau and Inner Mongolian Plateau, we analyzed the general and differential mechanisms of biomass allocation (plant biomass ratio of root to shoot, R/S) in temperate vs. alpine grasslands. We found that the R/S exhibited large variations, ranging from 3.89 to 45.10 in temperate grasslands and from 4.74 to 80.72 in alpine grasslands. The R/S decreased with increasing precipitation in both grasslands, whereas it weakly related to temperature. Plant functional group had highest importance on R/S than mean annual precipitation, mean annual temperature, soil nitrogen and phosphorus availabilities, and plant richness and diversity index. Climate factors indirectly but strongly drove R/S by mainly changing plant functional group compositions. Particularly, forbs affected R/S more than other dominant plant functional types. This information can provide a profound insight into the biomass allocation dynamics in grasslands at regional level under climate change scenarios. [ABSTRACT FROM AUTHOR]

• Evolutionary history affected plant biomass responses to drought. • Gymnosperms biomass was more sensitive to drought than that of angiosperms. • Evergreen gymnosperms were more sensitive to drought than deciduous ones. • Weaker responses in C4 herbs were mainly due to phylogenetic niche conservatism. • Effects of drought intensity on biomass responses were prevalent. Divergent responses of plant biomass to drought were found across hundreds of manipulative experiments. While many researchers have explored the influences of plant functional types (PFTs) and climatic conditions, few focus on the importance of evolutionary history. Here we compiled a global dataset of the responses of plant biomass and biomass allocation to the experimental drought from 281 studies conducted on 329 wild species and conducted both traditional and phylogenetic meta-analyses to explore the potential role of evolutionary history in affecting the differences among PFTs and the regulation effects of environmental conditions. We found that there were no consistent differences in biomass responses to drought between gymnosperm and angiosperm woody plants when the traditional meta-analysis was applied. Taking the phylogenetic information (the proxy of evolutionary history) into account resulted in more sensitive responses in gymnosperms than angiosperms but with great uncertainty, probably due to the high hydraulic diversity in both groups. The observed higher drought sensitivity in evergreen gymnosperms than deciduous ones, and in C3 herbs than in C4 ones were mainly derived from the phylogenetic relatedness among species. The influences of drought intensity were prevalent in both traditional and phylogenetic meta-analyses. These results highlight the vital role of plant evolutionary history played in affecting plant responses to drought. Given the potentially complicated interactions of climatic change and evolutionary history, we call for experiments that aim to investigate the role of phylogenetic relatedness on plant and ecosystem functions in future studies. [ABSTRACT FROM AUTHOR]

In mangrove forests, the hydroperiod is strongly related to tidal dynamics, where the periodic oceanic water movement regulates the level, duration, and frequency of the flooding events. In fringe mangrove forests, Rhizophora mangle propagules deal with variable hydroperiod conditions that sometimes compromise their survival. To disentangle the combined effects of duration and intensity of flooding on physiological and growth variables, we imposed a continuous experiment with three levels of flooding and four flooding durations on seedlings of R. mangle. We collected data at 3 and 6.5 months after exposure to the treatments. Propagule reserves allowed plants to evade the effects of the flood level after a 3-month treatment period. After a 6.5-month exposure, physiology and growth were modulated by the flooding time. Individual plants had higher stem length and lower root and total biomass at prolonged and high flooding levels compared to any other flooding combinations. In both ages, the highest total plant biomass was exhibited in the medium flooding levels and 6 h flooding duration. The plasticity index was higher for morphological and biomass variables than for physiological variables. The high morphological plasticity of R. mangle plants constitutes a competitive advantage to colonize flooded sites in fringed mangrove areas. Our results identify schemes to improve the success of mangrove restoration plans, a critical tool for carbon sequestration and ecosystem service provision. • Mangrove seedlings enhance their flood tolerance with age. • High flooding increased stem mass fraction and length. • High flooding reduced foliar area, root, and total plant mass. • Increased flooding duration decreases stem biomass and length. • Stem and root variables showed the largest phenotypic plasticity. [ABSTRACT FROM AUTHOR]

Groundwater and its associated nutrients sustain the establishment and persistence of phreatophytes. Rapid root elongation immediately after germination is vital for desert species to access deep water sources to avoid water-deficit stress. However, the growth strategy and responses to nutrients and water of young phreatophyte seedlings before their roots reach the water table are poorly understood, especially in the scenarios of nitrogen (N) deposition and drought. We investigated how simulated N deposition and drought affect the plasticity of Alhagi sparsifolia seedlings by multiple eco-physiological mechanisms. Seedlings were planted under drought-stressed or well-watered conditions and subjected to various levels of N addition (0, 3.0, 6.0, or 9.0 gN·m−2 yr−1). The amounts of N and water independently or interactively affected the photosynthetic traits, drought tolerance characteristics, morphological traits, biomass allocation strategy, and nutrient distribution patterns among the plant organs. Moreover, changes mediated by N addition at the leaf level reflected the drought acclimation of the seedlings, which may be related to biomass and nutrient partitioning between organs. The roots were found to be more sensitive to variation of the N:phosphorus (P) ratio, and greater proportions of biomass, N, and P were allocated to resource-acquiring organs (i.e., leaves and fine roots) than to other tissues. A. sparsifolia adopts numerous strategies to tolerate drought, and additional N input was crucial to enhance the growth of drought-stressed A. sparsifolia , which was mainly attributable to its positive impact on the N and P uptake capacity mediated by increased biomass allocation to the roots. Image 1 • Alhagi sparsifolia exhibits several drought-tolerant strategies at seedling stage. • N supplementation promotes growth of A. sparsifolia under drought conditions. • Drought acclimation of A. sparsifolia is related to biomass/nutrients partitioning. • N addition improves N/P uptake by increasing biomass of fine roots under drought. [ABSTRACT FROM AUTHOR]

Dominants are key species that shape ecosystem functioning. Plant dominance is typically assessed on aboveground features. However, belowground, individual species may not scale proportionally in relation to their aboveground dimension. This is especially important in ecosystems where most biomass is allocated belowground, including grassy and shrubby biomes. [ABSTRACT FROM AUTHOR]

The medicinal plant Panax notoginseng is considered a promising source of secondary metabolites due to its saponins. However, there are relatively few studies on the response of saponins to nitrogen (N) availability and the mechanisms underlying the N-driven regulation of saponins. Saponins content and saponins -related genes were analyzed in roots of P. notoginseng grown under low N (LN), moderate N (MN) and high N (HN). Saponins was obviously increased in LN individuals with a reduction in β-glucosidase activity. LN facilitated root architecture and N uptake rate. Compared with the LN individuals, 2872 and 1122 genes were incorporated into as differently expressed genes (DEGs) in the MN and HN individuals. Clustering and enrichment showed that DEGs related to "carbohydrate biosynthesis", "plant hormone signal transduction", "terpenoid backbone biosynthesis", "sesquiterpenoid and triterpenoid biosynthesis" were enriched. The up-regulation of some saponins-related genes and microelement transporters was found in LN plants. Whereas the expression of IPT3 , AHK4 and GS2 in LN plants fell far short of that in HN ones. Anyways, LN-induced accumulation of C-based metabolites as saponins might derive from the interaction between N and phytohormones in processing of N acquisition, and HN-induced reduction of saponins might be result from an increase in the form of β-glucosidase activity and N-dependent cytokinins (CKs) biosynthesis. • Low nitrogen-induced accumulation of saponin might derive from the interaction between nitrogen and phytohormones. • High nitrogen-induced depression of saponin might be caused by an increase in β-glucosidase activity and nitrogen-dependent cytokinin. • First study on nitrogen-driven biosynthesis of triterpene saponins in Panax.notoginseng. • Nitrogen-driven changes in expression of genes showed positive correlation with secondary metabolites content. [ABSTRACT FROM AUTHOR]

• The decreasing trend in photosynthesis induced by drought stress had to be reversed by N addition and appeared to increase. • N addition increased the aboveground biomass regardless of water conditions, whereas root biomass appeared to decrease under normal water conditions and increased under drought stress. • Drought stress caused the C use strategy of Mongolian oak seedlings to shift from growth to protection and defense even when N availability was adequate. Water and nitrogen (N) are major constraints that affect plant growth and survival. N deposition can enhance plant photosynthetic capacity and drought tolerance. However, the ecophysiological processes of plants in response to N deposition associated with drought stress are unclear. We investigated the allocation patterns of biomass and nonstructural carbohydrates (NSC) among different organs in response to the addition of ammonium nitrate in Mongolian oak seedlings along a drought stress gradient. This study used pot experiment with three levels of N addition (CK: 0, LN: 5 and HN: 10 g N m−2 yr−1) in conjunction with three irrigated water volumes (W0: 36 L, W1: 25 L, reduction 30%, and W2: 18 L, reduction 50 %). The results showed drought stress, resulting in a decreasing trend in photosynthesis, had been reversed by N addition, and trends in water use efficiency also appeared to increase. Similarly, drought caused a decreasing trend in the biomass and the decreases in the ratio of root-to-shoot (R:S) and total biomass at the whole-seedling level. The enhancements in aboveground biomass were induced by N addition regardless of water conditions. Adversely, root biomass appeared to decrease under normal water conditions (W0) and increased under drought stress. In addition, leaf soluble sugar (SS) concentration and leaf SS: starch increased with N addition under W0 and decreased under severe drought (W2). When water and N availability were abundant, the carbon (C) use strategy of Mongolian oak seedlings focused on aboveground growth to get more carbohydrates. However, when water availability was in severe deficit, the C use strategy of seedlings shifted from growth to protection and defense by restoring more carbohydrates in stems or roots to survive the harsh environments, even when N availability was adequate. This study provided new insights into the understanding of C use strategy and drought survival mechanism in response to environmental change. [ABSTRACT FROM AUTHOR]

Many amphibious clonal plants in aquatic-terrestrial ecotones commonly expand from terrestrial to aquatic habitats. Nutrient availability and light intensity are both key factors affecting plant growth in aquatic habitats, but little is known about the role of nutrient availability and light intensity in aquatic habitats during the expansion of amphibious clonal plants from terrestrial to aquatic habitats, when clonal integration is maintained. We conducted a greenhouse experiment to simulate expansion from terrestrial to aquatic habitats of the amphibious clonal plant Hydrocotyle vulgaris. We grew basal portions of clonal fragments in soil and connected the apical portions of the same fragments to water which subjected to three levels of nutrient availability under a low or a high light condition. High nutrient level and light condition increased the growth of the apical portions of H. vulgaris and thus increased the performance of the whole clones. Meanwhile, root-shoot mass ratio of the apical portions and the basal portions were higher at the high light condition and the low nutrient level. Results suggest that the relatively high levels of nutrients and light condition in aquatic habitats can improve the expansion of apical portions from terrestrial to aquatic habitats. Our results also suggest that maintaining clonal integration may benefit the expansion of H. vulgaris via the trade-off of biomass allocation which can optimize the utilization of resources. These results may provide theoretical basis for community dynamics prediction and vegetation restoration in the ecotones such as wetlands. • We tested the effects of nutrient and light on the growth of H. vulgaris when expanded from terrestrial to aquatic habitat. • High levels of nutrients and light promote the growth of apical ramets and whole plants of H. vulgaris. • Root-shoot mass ratio responds differently to the variation of nutrient availability and light intensity. • High levels of nutrients and light may contribute to the expansion of H. vulgaris from terrestrial to aquatic habitats. [ABSTRACT FROM AUTHOR]

It has been hypothesized that plants compete actively by allocating more resources to competitive organs and activities in response to neighbours, and this can reduce population performance, such as yield in crops. Root proliferation and reduced aboveground growth in response to the presence of roots of a neighbouring plant in experiments with vs. without root dividers between pairs of plants has been reported in several studies, but this result has been criticized as a possible artefact resulting from differences in soil volume available to roots in the two treatments. To address this possible confounding effect, we conducted a pot experiment with a traditional landrace and a modern cultivar of wheat (Triticum aestivum). Pairs of spring wheat plants were grown in pots with two types of root dividers (a) film, which completely divides the soil into two volumes, and (b) fine nylon net, through which roots cannot grow but chemical cues can move. We hypothesized that the root proliferation in response to root interactions would reduce aboveground growth. Wheat plants produced significantly more belowground and less aboveground biomass when interacting through the net dividers than when roots were completely separated. This effect was smaller, but still significant, in the modern cultivar. Our results confirm neighbour-induced root proliferation resulting in a so-called "tragedy of the commons" in an important crop species. The results also suggest that this response has decreased over the course of crop breeding, due to inadvertent "group selection", and that there is further potential to increase yields by reducing or eliminating this response. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Leaf mass fraction (LMF) is mainly related to draught tolerance. • Leaf area ratio (LAR) is mainly related to light capture. • LMF and LAR play different roles in the acclimation of plants. Abstract Understanding how plants allocate biomass to different organs is of high importance since biomass allocation among organs determines many growth processes. Biomass allocation among plant organs is driven by environmental conditions, while functional traits can also be potential covariates to understand the allocation of biomass. However, the relationships between functional traits and biomass allocation remain poorly known and studied. We investigated the relationships of two biomass allocation indicators, including leaf mass fraction (LMF) and leaf area ratio (LAR), with six economic traits and five hydraulic traits across 30 woody species. We found that LMF and LAR showed different relationships with economics traits. In addition, a significantly negative correlation was observed between LMF and leaf water potential at turgor loss point (TLP), but no significant relationship was found between LAR and TLP. Principal component analyses showed that LMF-related traits and LAR-related traits could be divided into two groups. Taken together, LMF is mainly related to draught tolerance while LAR mainly related to light capture. Although LMF and LAR are two significantly correlated biomass allocation indicators, they play different roles in the acclimation of plants. Researchers should focus on the different functions of these two indicators and the different relationships with other functional traits in the further research. [ABSTRACT FROM AUTHOR]

• Southern-edge Q. suber seedlings invest higher biomass proportion in roots than northern-edge populations. • Under extreme drought, southern seedlings keep active photosynthesis for longer time than northern ones. • Root:shoot ratio is directly related to drought resistance. The changes in climate registered at the planetary scale threaten the persistence of current populations for many plant species, with effects particularly evident at the edges of species distributions. However, intraspecific differences in functional traits could modulate the plant responses to the expected increase in drought. Using a trait-based approach, we evaluated under controlled conditions how Quercus suber seedlings from the latitudinal edges of the distribution range of the species respond to different watering treatments in terms of vegetative growth and biomass allocation. In addition, we simulated an extreme drought by stopping watering until death to determine chemical and physiological traits under drought stress and to identify which morphological traits were more associated to drought resistance (expressed as survival time without watering). Seedlings from the northern provenance presented higher aboveground biomass allocation (i.e. shoot length and biomass allocation to shoot and leaves), while the southern ones were characterised by longer roots and higher biomass allocation to roots. Under extreme drought, seedlings from the southern provenance maintained higher photosynthetic rates than northern seedlings and were able to modulate their water-use efficiency (estimated from δ13C) depending on environmental conditions, which allowed them to survive for a longer period. Finally, drought resistance was partially explained by the plant biomass allocation pattern. Traits related to growth in height and light interception were negatively related with drought resistance, whereas traits involving investment in root biomass were positively related with resistance. These geographical differences evidence a local adaptation to drought at the southern edge of Q. suber distribution. Our results highlight the importance of the conservation of the genetic resources that peripheral populations harbour at distribution edges. [ABSTRACT FROM AUTHOR]

• Clonal integration improved photochemical activity and growth performance of ramets growing in unfavourable patches. • Clonal integration may be result in lower fitness for whole clonal fragments subjected to severe drought stress. • Capacity of division of labour for clonal plants is dependent on contrast of resource availability. Clonal integration allows translocation of water between interconnected ramets, improving fitness of clonal plants growing in heterogeneous water availability. However, few studies have been conducted to investigate the effects of clonal integration on physiological responses of clonal plants suffering from heterogeneous water availability. A greenhouse experiment was conducted by using clonal fragments of the stoloniferous herb Centella asiatica with two successive ramets. The basal ramets were grown in patches with 40% soil moisture (high water availability), while the apical ramets were grown in patches with 40% (high water availability), 20% (medium water availability) and 10% soil moisture (low water availability) respectively. Stolons between the basal and apical ramets were severed (clonal integration impeded) or retained intact (clonal integration allowed). Our results showed that clonal integration relieved negative impact of water deficiency on the apical ramets in terms of photochemical activity and growth performance. Clonal integration modified biomass partitioning both for the apical ramets growing in low water availability and the basal ramets growing in high water availability. In addition, significant cost of clonal integration was observed in terms of growth performance of whole clonal fragments. A possible explanation is that increased biomass allocation to root may reduce capturing of light energy, producing negative effect on biomass accumulation of the basal ramets under high water availability contrast between patches. The results suggest that the net benefit of clonal integration may depend on the contrast of resource availability between interconnected ramets. [ABSTRACT FROM AUTHOR]

Highlights • Four pines and four spruces in a 2 × 2 factorial of CO 2 and soil moisture. • Overall, pines respond better to eCO 2 and soil moisture stress. • Shade-tolerant spruces perform better in eCO 2 than shade-intolerant spruces. • Greater the mass, greater the response to eCO 2 and soil moisture. • Supports shift toward increased use of pines in NE N. America. Abstract Growth, components of growth, and biomass allocation were quantified for eight species in two commercially important genera, Pinus and Picea , grown in a 2 × 2 factorial of atmospheric CO 2 and soil moisture stress. Four of the pines and three of the spruces are native to eastern North America; a fourth spruce, Norway spruce (NS: P. abies), is native to Europe but is used for reforestation in northeastern North America. Height, basal diameter (BD), and total biomass response of pines were often more than two times greater than that of spruces under elevated CO 2 (eCO 2). A significant species × CO 2 interaction for total biomass was a result of species' differential response to eCO 2 : Pinus rigida had the greatest biomass stimulation (59%), followed by P. resinosa (39%), P. strobus (26%), and P. banksiana (19%). Among spruces, Picea glauca showed the greatest response (30%), and P. mariana the least response under eCO 2 (5%). Overall, soil moisture stress reduced total productivity by 12%. Most pines did have greater growth under moisture stress, and NS and BS grew well. Percent needle mass was lower under eCO 2 , but this was not due directly to eCO 2 but to ontological changes. Controlling for size, pines had 20% greater needle biomass than spruces, while having a negative relationship to total biomass. A comparison of total biomass under eCO 2 in relation to aCO 2 by species showed that overall, the greater the species mass, the greater the mass gain under eCO 2, and the greater the mass loss under drought conditions. In addition, our results for spruces lend strong support to the theory that late-successional species have greater growth response under eCO 2 than early to mid-successional species. A diverse portfolio of tree species for artificial reforestation would help forest management adapt to the many uncertainties over future environments and markets, but our results on responses in spruces and pines to eCO 2 and soil moisture stress support a shift toward increased use of pines in forest management and artificial reforestation. [ABSTRACT FROM AUTHOR]

Abstract Ozone (O 3) pollution can alter carbon allocation and reduce tree growth - both above and below ground, but the extent of these effects depends on the variation in soil water and nutrient availability. Here we present the accumulation and allocation of biomass in poplar clone 546 (Populus deltoides cv. '55/56' × P. deltoides cv. 'Imperial') for one growing season at two O 3 concentrations (charcoal-filtered air [CF] and non-filtered air + 40 ppb of O 3 [E-O 3 ]), two watering regimes (well-watered [WW] and reduced watering at 40% of WW irrigation [RW]) and two soil nitrogen addition treatments (no addition [N0] and the addition of 50 kg N ha−1 year−1 [N50]). We found that the deleterious effects of E-O 3 depended on the supply of water and nitrogen. Specifically, when the supplies of water and/or N (WW and/or N50) were abundant, E-O 3 significantly reduced whole plant biomass by >15% but had no significant effect on biomass when these supplies were limited (RW and N0). A significant reduction of biomass by E-O 3 occurred earlier in fine roots than in other plant organs, indicating greater sensitivity of fine root to E-O 3. These results suggest that rising O 3 concentrations may not ubiquitously lead to a large reduction in plant biomass since plant growth is often jointly constrained by water and nutrients. Graphical abstract Unlabelled Image Highlights • The negative effects of O 3 depend on the amount of available water and nitrogen. • O 3 -induced the reduction in biomass was limited under low water and nutrient availability. • Biomass decreased but root to shoot ratios increased with the number of limiting factors. • Fine root biomass was significantly decreased by elevated O 3 at low O 3 dose. [ABSTRACT FROM AUTHOR]

Highlights • Bilberry benefits from forest land use continuity and Scots pine planting. • Northern red oak admixture in pine monoculture contributes to bilberry decline. • Bilberry cover, aboveground biomass and fruit yield decrease under closed canopies. • Northern red oak presence modifies biomass allocation in bilberry shoots. Abstract Tree species diversity can positively affect numerous forest functions. This is why Scots pine monocultures, widely promoted in Central Europe since the 18th Century, are converted into mixed stands, also with broadleaved species of alien origin. Here we studied the impacts of Northern red oak (Quercus rubra) introduction and forest continuity (ancient vs. recent forests) on bilberry (Vaccinium myrtillus) – a dominant component of the forest understory and very important ecosystem services provider in temperate coniferous (Pinus sylvestris) forests. We measured bilberry cover, density and height of shoots, fruit productivity (number and biomass of berries) as well as biomass of stems and leaves. 2000 bilberry shoots (ramets) were collected in 200 plots located in four types of Scots pine forest in central Poland: recent and ancient forests, with and without Q. rubra. At the individual (ramet) level we found decreased aboveground biomass and fruiting leaf mass fraction of bilberry in recent pine monoculture and in both types of forest with Q. rubra. Presence of Q. rubra also modified the trajectory of the allometric relationship between biomass and height: plants with the same height had lower biomass. At the population level we found a decrease of shoot density, biomass and fruiting, which resulted from effects at the individual shoot level and from lower density. At the ecosystem level these relationships were modified by decreased cover of bilberry in the understory layer and bilberry fruit biomass in recent forests (with and without Q. rubra) and in ancient forest with Q. rubra. Results clearly indicated that V. myrtillus benefited from the continuity of Scots pine forests and declined after Q. rubra introduction. As V. myrtillus serves as shelter and provides food for numerous animal species, decreases in bilberry cover and biomass can have far-reaching consequences for biodiversity and population dynamics of numerous species which occur naturally in Scots pine forests. Results show that it can also result in a decrease in availability of non-wood forest products. Therefore, as part of sustainable forest management, we suggest limiting admixture of invasive Q. rubra (as well as other broadleaved species) into pine monocultures in areas with abundant V. myrtillus cover. [ABSTRACT FROM AUTHOR]

• We grew seven C 3 annuals at a factorial of CO 2 (160-450-750 ppm) and soil water availability (100-40-20%). • Compared to well-watered conditions the relative effect of drought was the same at all CO 2 conditions. • Across all traits measured, we found mostly additive effects of CO 2 and water. • In drought prone regions, results suggest CO 2 fertilization will not counter the effects of reduced water availability. Carbon dioxide and water are crucial resources for plant growth. With anthropogenic fossil fuel emissions, CO 2 availability is and has been increasing since the last glacial maximum. Simultaneously water availability is expected to decrease and the frequency and severity of drought episodes to increase in large parts of the world. How plants respond to these two changes will help in understanding plants' responses to climate of the future. Here we sought to understand how drought affects plant traits responses to CO 2 and whether there are trade-offs in responsiveness to low and elevated CO 2 and drought. We grew seedlings of seven C 3 annuals at past low (160 μl l−1), ambient (450 μl l−1) and elevated (750 μl l−1) CO 2. At each concentration plants were subjected to well-watered conditions (100% soil water availability, SWA), 40% SWA or 20% SWA. We measured biomass allocation, relative growth rate, tissue N concentration, and gas exchange. Compared to well-watered conditions plant size was an important element in the absolute response to SWA decrease, i.e. the smaller, slow growing species were unaffected by drought at low CO 2. Plants allocated less mass to root tissue at low CO 2 contrasting with increased root mass fraction at lower SWA at ambient CO 2. Across all traits measured, we found mostly additive effects of CO 2 and water. As due to climate change regions become more drought prone these results suggest CO 2 fertilization will not counteract the effects of reduced water availability. [ABSTRACT FROM AUTHOR]

Highlights • Waterlogging leads to only few changes in seedlings' above ground morphology. • Waterlogged seedlings with less pneumatophores show lower root system biomass. • Leaf water potential and leaf gas exchange are unaffected by long-term waterlogging. Abstract Oil palm (Elaeis guineensis Jacq.) apparently tolerates long-term waterlogging and numerous pneumatophores are evident morphological adaptation. The number of pneumatophores per plant is, however, quite variable. Thus we hypothesized that a higher number of pneumatophores may attenuate the stress effects on root system growth and induce higher tolerance to long-term waterlogging in oil palm seedlings. To test this hypothesis we compared morphological and physiological traits in well-watered (control) and waterlogged plants with 2–10, 30–40, 60–70, and 90–120 pneumatophores after ca. 77 days of waterlogging. Plant height was similar between control and waterlogged plants with 90–120 pneumatophores, but it was 21% lower in plants with 2–10 pneumatophores than in control. The stem diameter and bulb diameter and biomass were 16, 20 and 42% higher in waterlogged plants than in control, independent of number of pneumatophores. Similar number of leaves and leaflets were observed regardless of watering regime and pneumatophore number, but total leaflet area and leaflet biomass were higher in plants with 90–120 pneumatophores than in other plants. Root system biomass was remarkably decreased in waterlogged plants; however, such decreases were more expressive in plants with 2–10 pneumatophores. Leaf water potential, leaf gas exchange and chlorophyll fluorescence were unaffected by waterlogging. Thus, we conclude that waterlogging causes few changes in seedlings' above-ground morphology but remarkably affects root system development, mainly in those plants with lower number of pneumatophores. Regardless of pneumatophores, the stressed oil palm seedlings were able to adjust their leaf water status and gas exchange to cope properly with the imposed waterlogging. [ABSTRACT FROM AUTHOR]

• The vertical distribution patterns of C, N and C:N were different and affected by environment. • Grasslands adopted different biomass allocation strategies as adaptations to environment. • The nitrogen has a stronger effect on the C:N ratio within vegetation than carbon. The accumulation, transport and distribution of photosynthates within plants not only affect the ratio of shoot-to-root biomass, but also change the distribution pattern of nutrient elements in different organs and tissues. A full understanding of the allocation patterns of biomass and nutrient elements within plants, is helpful to strengthen our understanding of the above- and belowground ecosystem functions. However, at present, we do not know enough about the aboveground–belowground allocation of biomass, carbon (C) and nitrogen (N) contents, and, in particular, the corresponding vertical distribution pattern belowground and its environmental impact. At the community scale, the changes in vegetation community attributes measured in the field can reflect the long-term adaptation and subsequent adaptation strategies of vegetation to the regional environment and environmental changes. In this study, the vertical distribution patterns of community biomass and the carbon and nitrogen contents with soil depth in an alpine grassland on the eastern Qinghai–Tibet Plateau were investigated based on the transect method. Our results show the following: (1) Alpine grasslands can respond to differences in hydrothermal resource availability by changing biomass allocation patterns. In low-temperature and high-humidity environments, aboveground and belowground biomass allocation supports the isometric growth hypothesis. However, in environments with less soil moisture or high temperature and humidity, the aboveground and belowground biomass distributions support the allometric allocation hypothesis. (2) The vertical distribution patterns of the C content, N content and carbon: nitrogen ratio (C:N) within plants are different. From the leaves to the root system, with the increase in root depth, the C content demonstrated a vertical distribution pattern of first decreasing and then increasing, and the N% demonstrated a gradual decreasing distribution pattern, while the C:N ratio demonstrated an exponential increasing distribution pattern. (3) The change rate in C%, N% and C:N related to the soil depth was affected by environmental hydrothermal conditions. C% and C:N ratio changed more rapidly with root depth under low temperature and high humidity. The change rate of N% was mainly affected by temperature and changed more rapidly with root depth at low temperatures. (4) When exploring the relationship between the content of elements within plants, it is necessary to combine both the above- and belowground compartments. There was a nonlinear quadratic relationship between the carbon and nitrogen contents within plants. [ABSTRACT FROM AUTHOR]

Typha domingensis is a dominant plant species in the Everglades Stormwater Treatment Areas, freshwater wetlands constructed to reduce phosphorus (P) levels in stormwater runoff prior to discharge into the Everglades. Water depth and duration of inundation can negatively affect the health of these plants. To determine the effect of water depth and inundation duration, Typha plants were grown in this study in a series of 15 test cells, 0.2 ha in area, and exposed to five water-depth treatments over 10 months: control (40 cm), shallow (61 cm), moderate (84 cm), deep (104 cm) and extremely deep (124 cm). Mean adult Typha densities declined from 14.1 shoots m−2 in the control to 10.9 and 10.5 shoots m−2 in the deep and extremely-deep treatments, respectively. However, only mean juvenile Typha densities were significantly different among water-level treatments, declining from 3.2 juveniles m−2 in the control to 1.2 and 0.6 juveniles m−2 in the deep and extremely-deep treatments, respectively. Typha leaf elongation rate (LER) was significantly higher in the deeper treatments, with the highest rates measured during the active growing season (July to October). LER increased from 6.84 cm day−1 during June baseline measurements to 8.89 cm day−1 in the deeper treatments after eight weeks of continuous inundation. Typha showed morphological plasticity to adapt to deep water through changes in morphology and biomass allocation. Typha grew significantly taller and heavier to adapt to deep-water conditions and facilitate gas exchange between the above and belowground tissues. Ramet height of Typha harvested at the end of the study averaged 343 and 374 cm in the deep and extremely-deep treatments, respectively, compared to 285 cm in the control. Likewise, the weight of individual adult ramets was significantly greater in the deeper treatments (256 g ramet−1) compared to the control (123 g ramet−1). Although none of the water-level treatments resulted in a total collapse of their Typha populations, increased LER in the deeper treatments resulted in less structural support in stems, causing substantial Typha lodging when water levels were lowered at the end of the study. These findings provide valuable insight into the effect of different water-level inundations on plant responses and overall health of Typha populations in the STAs. • Lower adult densities with depth were attributed to decline in juvenile recruitment. • The decline in Typha juvenile density was more pronounced at water depths ≥84 cm. • Typha mitigated water stress by growing taller via leaf elongation. • As water depth increased Typha height and weight significantly increased. • Leaf elongation in deeper treatments resulted in less structural support of Typha. [ABSTRACT FROM AUTHOR]

Highlights • Gymnocalycium quehlianum and G. monvillei present determinate growth of the primary root. • Primary root length differs between the species and among the elevation populations. • Species and populations growing at the more stressing sites present a higher length of the primary root. • Allocation theories explains the patterns found: higher allocation to roots at the more stressing habitats. Abstract Determinate primary root growth in Cactaceae has been interpreted as an adaptation to dry environments. However, little information is available regarding ecological patterns of this process. Our research question was whether primary root length is affected by the determinate growth pattern of the plant or following predictions from resource allocation theories. We analyzed the presence of apical meristem exhaustion and patterns of primary root length (PRL), days until the end of growth (day's post-germination, DPG) and seed mass in Gymnocalycium monvillei and G. quehlianum , which present different elevation distributions and wide elevation ranges. We analyzed five elevation provenances for G. monvillei (878, 1250, 1555, 1940 and 2230 m a.s.l.), and three for G. quehlianum (610, 950 and 1250 m a.s.l.). One hundred seeds per species per altitude were set to germinate in vertical petri dishes. We measured PRL and DPG in each seedling and also seed mass. Both species present determinate growth and PRL varied between species and among populations. PRL was higher in G. quehlianum. DPG was related to differences between species in PRL: roots of G. quehlianum grow for a longer period. In both species we found differences among elevation provenances, with higher PRL at the extremes of the distribution. Among elevation provenances, DPG was significantly related to PRL in G. monvillei , and marginally significantly related in G. quehlianum. Seed size was not related to differences in PRL between species or among elevation provenances. The comparison between species and among elevation provenances suggests that a higher PRL would be related to more extreme environments; this assumption agrees with plant resource allocation theories, which predict a lower shoot : root ratio with increasingly stressful environments. [ABSTRACT FROM AUTHOR]

Accurate estimates of aboveground biomass (AGB) strongly depend on the suitability and precision of allometric models. Although additive allometric equations are expected to reduce uncertainties due to additivity property between biomass of tree components, methods for developing biomass equations do not comply with the additivity property. This study aimed to evaluate biomass allocation patterns within tree components, and to develop additive allometric equations for Combretum glutinosum and Terminalia laxiflora in West Africa. Sixty trees were destructively sampled and measured for stem, branch and leaf biomass in Sudanian savannas of Burkina Faso. Biomass allocation to stem, branch and leaf was assessed by calculating the biomass fractions for each component. Bivariate relationships between biomass fraction and diameter at beast height (dbh) were further examined. For each biomass component we tested three non-linear allometric equations based on dbh alone, and dbh in combination with height and/or crown diameter as independent variables. Seemingly Unrelated Regressions were used to fit a system of additive biomass allometric equations. Branch biomass accounted for between 60 and 70% of the AGB. Branch mass fraction increased with increasing stem diameter while a reverse trend was observed for leaf and stem mass fractions. The decline in the mass fraction was more pronounced for the leaf than the stem. Additive biomass models developed for the two species exhibited good model fit and performance, with explained variance of 68–89%. The models developed in this study provide a robust estimation of tree biomass components and can be used in Sudanian savannas of West Africa. [ABSTRACT FROM AUTHOR]

Although Chinese fir ( Cunninghamia lanceolata (Lamb.) Hook) plantations are widely grown for timber production in southern China, they have low biodiversity and provide limited ecosystem services. To address this problem, C. lanceolata are increasingly mixed with broadleaf Schima superba Gardn. & Champ. (Theaceae). The success of these mixed plantations relies on introducing each species in the appropriate sequence, which requires understanding how tree species respond to light variations. We therefore compared S. superba and C. lanceolata seedling light tolerance in shaded houses under five light gradients (5%, 15%, 40%, 60%, and 100% sunlight). Our findings showed that S. superba seedlings exhibited greater net height increment (ΔHt), net diameter growth (ΔDia), leaf area, root mass, stem mass, leaf mass, and total mass under low light conditions (15% sunlight). However, as sunlight increased, these growth variables became higher in C. lanceolata seedlings. With more sunlight, both species experienced a drop in height to diameter ratio (HDR), and specific leaf area (SLA), but an elevated root to shoot ratio. Additionally, under the same light levels, S. superba seedlings exhibited greater leaf area and root to shoot ratio than C. lanceolata seedlings. Our results suggested that S. superba might be more suitable for underplanting beneath a heavy canopy due to its shade-tolerant traits. In contrast, C. lanceolata was less shade-tolerant, having an optimum seedling growth under full sunlight. These findings suggest that underplanting S. superba seedlings in C. lanceolata monoculture plantation (i.e., underplanting regeneration approach) could be a better silvicultural alternative than simultaneously planting both seedlings. [ABSTRACT FROM AUTHOR]

The light environment of trees is a strong driver for their growth and morphology. Manipulating the light regime in forests is one of the main tools available to control the forest development. This study analysed the effect of a drastic light addition through gap creation on beech saplings ( Fagus sylvatica L.) that had initially established under the canopy of mature trees. Altogether 6 gaps of varying size were created on an area of 4 ha. A total of 51 saplings were incorporated in this study. The saplings’ above- and belowground biomass compartments were destructively harvested along a light gradient. Relationships between light availability and growth increment, stress relief, biomass allocation, and growth morphology were analysed. Along the gradient of increasing light availability, beech saplings responded with an increased diameter growth, whereas the height growth remained unaffected. Also the root mass fraction increased at the expense of the leaf mass fraction. Other biomass compartments showed no significant trend. The mean branch weight also increased and the specific leaf area decreased. Other morphological traits were not affected by the light availability. The results lead to the conclusion that the morphological plasticity of the beech saplings towards light was not as high as initially expected. Furthermore, the sudden increase of light availability did not impose stress on the saplings. Finally, managing the light regime is appropriate to achieve specific goals. [ABSTRACT FROM AUTHOR]

Moringa oleifera Lam. and Ricinus communis L. are species known for their ability to survive in different environments; however, analyses of their capabilities to develop and explore clayed compacted soils are still not well covered. This study compares above- and below-ground development of Ricinus and Moringa in a subtropical compacted clayey soil. Seedlings of each species were germinated and monitored in field conditions during 12 months. After this period, 10 plants of each species were excavated to measure shoot versus root data along the soil profile. With the correlated data, we developed a model for each species to estimate root biomass and volume distribution. Results showed that Ricinus became a mature plant in a quarter of time than Moringa , but Moringa had 18% higher survival rate. Root volume distribution of both species was fitted by logistic and exponential models with 90% of their volume within the first 40 cm 3 around the tap root. Average lateral root inclination was −22° for Moringa and −36° for Ricinus . Root volume in Moringa was 5.5 times higher than that of Ricinus . The product of stem base by the crown-width for Moringa and stem base by plant-height for Ricinus were the best estimators (R 2  > 0.9) for below-ground biomass. We conclude that both species were capable to grow and reproduce in a clayey and compacted soil; nevertheless, Ricinus developed 16% more oblique and sinker roots to maintain its denser crown, while Moringa took advantage of the mass of its dense trunk and roots for a shallower exploration. [ABSTRACT FROM AUTHOR]

Due to the impact of climate change and rising atmospheric carbon dioxide concentrations, assessment of forest carbon pools becomes a crucial task for forest ecology. One of the scientific gaps in this task is the assessment of young tree stands, not included in forest inventories, due to lack of merchantable volume. We aimed to provide a comprehensive set of allometric equations (AEs) and biomass conversion and expansion factors (BCEFs) for young Scots pine tree stands and to develop models of tree stand biomass based on stand features easy-measurable by remote sensing: height and density. We used data collected in 77 tree stands of Scots pine ranging in age from 3 to 20 years in Western and Central Poland, covering forest, post-agricultural and post-industrial sites. Our dataset included 423 sample trees. Our study resulted in collection of 256 site-specific AEs, 12 generalized AEs and equations allowing for dynamic BCEF calculation. Due to lack of BCEF applicability for young trees, we also provided age- and height-dependent functions allowing for precise biomass estimation at the tree-stand level. It was found that tree-stand biomass increased with tree-stand age, height and volume, and decreased with increasing density in the chronosequence. BCEFs decreased with tree-stand age, height and volume and increased with increasing density. Using these relationships we provided stand-level equations based on BCEFs and on tree height – the stand characteristic which is easily obtained from airborne data. These two models did not show a big difference in accuracy. Thus, height-based models are expected to be useful for extensive assessments of young tree stand biomass and carbon sequestration, allowing for better estimation of forest carbon pools. Moreover, our models, in comparison with IPCC guidelines, give more precise values of carbon pools and biomass of young Scots pine tree stands. [ABSTRACT FROM AUTHOR]

• We compared two high-elevation pines with contrasting elevational distributions. • Specialist PIAL has a narrower elevation range, and generalist PIFL has a broader elevation range. • PIFL's acquisitive and conservative traits contribute to its generalist strategy. • PIFL may maximize light, C and water uptake when moisture is abundant earlier in the growing season. • We identified physiological mechanisms that underlie seedling establishment and survival. Plant species life history strategies are described by functional variation spanning an acquisitive and conservative resource use continuum. Specialist species can exhibit traits promoting one end of the continuum, while generalist species can display traits promoting both acquisitive and conservative resource use. Whitebark pine (Pinus albicaulis, PIAL) and limber pine (Pinus flexilis, PIFL) are two high-elevation pines that have similar growth and morphology, yet contrasting elevational distributions with PIAL viewed as a specialist inhabiting a narrower elevation range, and PIFL as a generalist inhabiting a broader elevation range. We compared the physiological and morphological traits of greenhouse-grown 5-year-old PIAL and PIFL. Our results suggest that PIFL's acquisitive and conservative resource use traits contribute to its generalist strategy and ability to inhabit a greater range of elevations than PIAL. PIFL had greater acquisitive resource use traits including: high-light tolerance (greater Q sat , greater fascicle density), increased biomass allocation to photosynthetic tissue (higher needle biomass, aboveground:belowground biomass, needle:branch + stem biomass), and higher C and water uptake (greater stomatal density and size, higher C assimilation rate), as well as greater conservative resource use traits including: greater physical stress resistance (shorter height, higher stem and branch diameters, greater branch and stem diameter:length), drought tolerance (higher SWC, leaf starch proportion), and drought avoidance (earlier budburst phenology, smaller hydroscape area) than PIAL. Our results suggest that PIFL may make more efficient use of high-light loads and maximize C and water uptake when moisture is abundant during spring snowmelt before the onset of dry summer conditions. Other conservative resource use traits describing cold tolerance, heat tolerance, and drought tolerance did not differ between species, suggesting that both species exhibit traits that promote similar conservative resource use enabling their overlapping persistence at higher elevations. Comparing the physiology of PIAL and PIFL within the same environment enables us to identify physiological mechanisms that underlie species establishment and survival, and how juvenile physiology contributes to their contrasting distributions and their generalist-specialist strategies. [ABSTRACT FROM AUTHOR]

This study proposes a simple yet practical semi-empirical approach for theory-guided fitting of biomass growth curves and prediction of biomass growth rate in aquatic plants. The model is based on a hyperbolic secant function, which describes the biomass growth and provides a straightforward solution for the biomass growth rate. The approach also provides an innovative theory-based method to predict the control of succession of plants since the maximum in the absolute growth rate of the aboveground biomass corresponds to the period when perennial macrophytes allocate biomass into their overwintering parts. Field experiments indicate that the biomass allocation pattern can be strongly affected by mechanical harvesting. For instance, the cutting scenario, which yielded the smallest mass and number of Sagittaria sagittifolia tubers per plant, had been performed at the thermal time values corresponding to the peak of aboveground biomass growth rate, the timing of which can be easily predicted using the model proposed in this study. [ABSTRACT FROM AUTHOR]

Wild tomatoes and relatives ( Solanum sect. Lycopersicon , sect. Lycopersicoides and sect. Juglandifolia ) constitute a recently derived clade inhabiting a wide range of habitats across latitudinal and altitudinal axes in South America, with important variation in plant morpho-physiological traits. It is not clear to what extent growth capacity and related traits depend on phylogenetic constraints, or are driven by each species’ adaptation to the climate of origin. The use of wild tomatoes to improve the adaptation of the domesticated species to variable environmental conditions requires knowledge on which wild species are most suitable for growth capacity improvement. Under common garden conditions, results show that the relative growth rate ( RGR ) in the tomatoes is better determined by its physiological (net assimilation rate, NAR ) rather than morphological (leaf area ratio, LAR ) component. Moreover, RGR is correlated with the climate of origin in arid and semi-arid habitat species, and display different biomass allocation strategies depending on the climate, particularly related to the green and senescent leaf fractions. When grown under the same conditions, the domesticated tomato showed important differences in leaf size and leaf mass per area ( LMA ) as compared to its wild relatives, suggesting modifications related to the domestication process. Several semi-arid species appear as suitable species to improve the domesticated tomato growth capacity under more arid cultivation conditions, as those predicted by climate change. [ABSTRACT FROM AUTHOR]

Area-efficient constructed systems for stormwater management and bioretention may involve large fluctuations in subsurface water levels. Such fluctuations challenge vegetation by forcing roots to explore deeper layers to access water during dry periods. In a controlled experiment, we studied growth patterns and the ability of Phragmites australis roots to track subsurface water level fluctuations of differing amplitude and frequency in substrates with contrasting water-holding capacity. We found that P. australis was able to adjust its rooting pattern to considerable subsurface water level fluctuations (to well below 120 cm), but that substrate characteristics can restrict its ability to adjust to larger fluctuations. Fluctuation amplitude was the driving factor for plant growth and biomass allocation responses, while substrate characteristics and fluctuation frequency were less important. When not exposed to large water level fluctuations, P. australis grew larger shoots and only explored intermediate rooting depths. There was a negative relationship between root and rhizome biomass, showing a resource-based trade-off and short-term costs of adjusting rooting patterns to large water level fluctuations. These results indicate that P. australis is suited for systems with considerable subsurface water fluctuations, but constraints on its flexibility need to be investigated. [ABSTRACT FROM AUTHOR]

Water deficit and nitrogen (N) deposition are two important factors affecting plant growth in the context of global change. Here we selected Ailanthus altissima , a locally important tree species in North China, to study the combined effects of soil water status and N addition on plant growth. Ailanthus altissima seedlings were exposed to two soil moisture conditions (35% and 75% of the saturated soil moisture content) and three N treatments (0, 5, and 15 g N m −2 year −1 ) in a greenhouse experiment. After 50 d of treatment, plant growth, biomass production and allocation, and leaf physiological parameters were determined. Water deficit significantly restricted some parameters of growth and biomass accumulation, like height and basal diameter, total biomass, lateral root biomass, leaf biomass, and stem biomass. Some physiological parameters were also affected significantly by water deficit, leaf N content and qP decreased as soil moisture decreased and WUE was highest in water deficit condition. However, the high N load increased crown area and total biomass, lateral root biomass, and root biomass. With respect to physiological parameters, net photosynthetic rate, leaf N content, ΦPSII and ETR were clearly higher in the high N addition group than in the control group. Overall, an interaction between water deficit and N load had no significant effects on plant growth. Based on the present study with A. altissima seedlings, considering their rapid growth rate, we conclude that this species is better adapted than other deciduous trees to water deficit and high N additions under future global change scenarios, making it suited for vegetation restoration and reconstruction projects in the warm temperate zone of China. [ABSTRACT FROM AUTHOR]

An increase in precipitation amount with prolonged inter-rainfall intervals is predicted to occur in the Inner Mongolia grassland in the future. However, how the native species respond to such alterations remains poorly understood. We collected the seeds of eight species from a natural community and raised their seedlings by pot culture. The responses of these species to manipulated precipitation amount and inter-rainfall intervals were examined by rainout shelters. The biomass production in seven out of eight species was enhanced by increased precipitation amount. However, the impacts of prolonged inter-rainfall interval differed substantially among species, with one being promoted, two suppressed and five not affected. For most species, biomass allocations among vegetative organs were neither affect by precipitation amount nor by inter-rainfall intervals. In contrast, the impacts on species’ reproductive allocation were highly species-dependent. Soil moisture, soil temperature and soil inorganic nitrogen played important roles in affecting species’ biomass production but the pathways, directions (positive or negative) and magnitudes were species-dependent. Given that these eight species jointly represent about 80% of community biomass production, the impact of altered precipitation pattern on grassland ecosystems may be more difficult to predict than that of altered amount. [ABSTRACT FROM AUTHOR]

Light availability in forests is a strong driver for forest development and diversity. Tree species develop differently under varying levels of light. Understanding the reasons for the individual growth strategies of tree species is crucial to understand dynamics of forest communities. This study aims at further disentangling aboveground biomass allocation patterns and growth variables for saplings of the tree species sycamore maple ( Acer pseudoplatanus L.), European beech ( Fagus sylvatica L.), and European ash ( Fraxinus excelsior L.). Plants were destructively sampled along a light gradient. European beech allocated more biomass to its branches and less to its stem, in comparison to the other two species. The relative growth rate (RGR) and leaf mass area (LMA) of all species increased towards an asymptote along the increasing light gradient, whereas the leaf are ratio (LAR) decreased. The rate of increase and decrease differed among the tree species. Net assimilation rate (NAR) and absolute growth rate (AGR) both also increased with light availability, but the distinction among the species was not as clear. This study showed varying reactions of all three species to light and allowed a quantitative distinction among the species regarding their shade tolerance (ash < maple < beech), whereas the individual reaction was not always the typical reaction associated with shade tolerance. [ABSTRACT FROM AUTHOR]

Floodplain forests serve a critical function in flood regulation and the global carbon (C) cycle due to their important role in C sink management. Barringtonia acutangula , a tree species adapted to floodplains has been managed traditionally over millennia as family and community forest in North East India. Prevailing traditional management of the Barringtonia forest restricts felling of trees while promoting uses of tree branches in fishery management and fuel wood production. Such management systems might have helped in sustaining floodplain family forests with a steady stock of biomass. However, our knowledge of their role in biomass stocks and C storage is still scanty. Therefore, the present study was undertaken to estimate the biomass and carbon stocks of Barringtonia forests and to understand their role in carbon sink management. The floodplain forest at the study site was stocked with 3204 trees ha −1 of Barringtonia . Allometric models were developed using harvested tree, and these were used for estimation of biomass and vegetation carbon stocks. Among the various models tested the power model using diameter at breast height (DBH) as an independent variable fitted tree biomass in different tree components (bole, sprout, branch and leaves) adequately. Total dry above ground biomass (AGB) estimated at 552 ± 23 Mg ha −1 in the Barringtonia floodplain forests was much larger than AGB reported for various forest types and agroforestry systems in North East India. Biomass allocation patterns revealed that out of the total biomass, the bole contributed the highest proportion (45%) followed by sprouts (27%), branches (24%) and leaves (4%). The above-ground carbon stock was estimated at 263 ± 11 Mg ha −1 . The quantity of biomass stock and the carbon storage in vegetation cover of Barringtonia forest suggest its direct influence on local, regional and even global climate. [ABSTRACT FROM AUTHOR]