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Background and Aims: Empirical studies and allometric partitioning (AP) theory indicate that plant above-ground biomass (MA) scales, on average, one-to-one (isometrically) with below-ground biomass (MR) at the level of individual trees and at the level of entire forest communities. However, the ability of the AP theory to predict the biomass allocation patterns of understorey plants has not been established because most previous empirical tests have focused on canopy tree species or very large shrubs., Methods: In order to test the AP theory further, 1586 understorey sub-tropical forest plants from 30 sites in south-east China were harvested and examined. The numerical values of the scaling exponents and normalization constants (i.e. slopes and y-intercepts, respectively) of log-log linear MA vs. MR relationships were determined for all individual plants, for each site, across the entire data set, and for data sorted into a total of 19 sub-sets of forest types and successional stages. Similar comparisons of MA/MR were also made., Key Results: The data revealed that the mean MA/MR of understorey plants was 2·44 and 1·57 across all 1586 plants and for all communities, respectively, and MA scaled nearly isometrically with respect to MR, with scaling exponents of 1·01 for all individual plants and 0·99 for all communities. The scaling exponents did not differ significantly among different forest types or successional stages, but the normalization constants did, and were positively correlated with MA/MR and negatively correlated with scaling exponents across all 1586 plants., Conclusions: The results support the AP theory's prediction that MA scales nearly one-to-one with MR (i.e. MA ∝ MR (≈1·0)) and that plant biomass partitioning for individual plants and at the community level share a strikingly similar pattern, at least for the understorey plants examined in this study. Furthermore, variation in environmental conditions appears to affect the numerical values of normalization constants, but not the scaling exponents of the MA vs. MR relationship. This feature of the results suggests that plant size is the primary driver of the MA vs. MR biomass allocation pattern for understorey plants in sub-tropical forests., (© The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Ambitious climate change mitigation goals require novel carbon (C) sinks in agricultural systems. Thus, the establishment of new hedgerows is increasingly attracting attention as a C sequestration measure. Despite hedgerows being a traditional agroforestry system, few studies have been conducted on hedgerow C stocks. Data on below‐ground biomass (BGB) in particular are limited. The aim of this study was therefore to quantify both above‐ground biomass (AGB) and BGB C stocks, as well as litter and soil organic C stocks, of established hedgerow systems by destructive sampling at three sites in northern Germany. The total biomass C (TBC) stock of the sampled hedgerows was 105 ± 11 Mg ha−1 on average. An additional 11 ± 2 Mg ha−1 were found in hedgerow litter and dead roots. Coarse roots (34% of TBC), stumps (22%) and harvestable biomass (20%) were the largest biomass C pools of the hedgerows. The BGB:AGB ratio was 0.7 ± 0.1, showing the importance of BGB in old hedgerow systems. Compared with other woody systems, these old hedgerows seem to have a different biomass distribution, with more biomass allocated below‐ground. About 15% of BGB C stock was stored in fine roots, whereas 85% was stored in coarse roots. The topsoil (0–30 cm) contained 85% of coarse root biomass C and 51% of fine root biomass C. Hedgerow C stock exceeded that of average German forests, and thus demonstrated their large potential for C sequestration when newly planted. This study provides detailed empirical data on C stocks in old hedgerow systems, and thus can be used to take hedgerow C sinks into account in C farming frameworks. [ABSTRACT FROM AUTHOR]

Selecting cultivars with greater biomass results in higher yields and greater carbon sequestration. Storage of atmospheric carbon in the plant/soil pool contributes not only to food security but also to mitigating climate change and other agroecological benefits. The objective of this study was to determine: (1) grain, residue, and root biomass yields; (2) harvest indexes; (3) residue-to-product ratio; (4) root-to-shoot ratio; (5) biomass carbon and nitrogen contents; and (6) C:N ratios for two new and two old winter wheat cultivars. The greatest yield difference was found between old Srpanjka (the lowest) and new Kraljica (the highest) cultivar where grain, residue, root, and total biomass yield was higher by 38%, 91%, 71%, and 64%, respectively. Total biomass was composed of 40–47% grain, 10–11% roots, 32–36% stems + leaves, 9–11% chaff, and 1–2% spindle. The range of HI was 0.45–0.53, RPR 0.91–1.25, and R:S ratio 0.12–0.13. For all cultivars, positive carbon and negative nitrogen balance within the plant pool was determined. Still, root biomass and rhizodeposition carbon remain open questions for a better understanding of agroecosystems' C dynamics. [ABSTRACT FROM AUTHOR]

Salt marshes are critical coastal ecosystems that provide numerous services. They are governed by complex biogemorphological interactions on multiple spatiotemporal scales. To simulate long-term salt marsh development in numerical models, smaller- and shorter-term vegetation processes are often neglected. This study investigates the importance of spatiotemporally and seasonally varying vegetation dynamics on decadal salt marsh development in an integrated numerical biogeomorphological model simulating a representative, idealized case of the Dutch Western Scheldt Estuary. The focus lies on the influence of seasonal vegetation dynamics, interspecific interactions between two salt marsh species, and the stabilizing effect of below-ground biomass with increasing vegetation age on critical shear stress, which results in spatially non-uniform erosion resistance of sediment and vegetation. By incorporating seasonal growth periods and varying characteristics of vegetation, we demonstrate the impact of species-specific traits on vegetation stability and morphological changes. Introducing an additional pioneer species that can establish further seaward reveals the sheltering effect and the long-term implications of this zonation for marsh development. Additionally, the influence of spatially and temporally varying below-ground biomass on sediment stability and vegetation's resistance to uprooting is significant for the biogeomorphological interactions. Comparison of the different model simulations to topographical data from the Dutch Western Scheldt Estuary shows that the model results are representing the morphological variability occurring in the field. Our findings highlight the complex biogeomorphological feedback that govern salt marsh development and show that models that neglect shorter-term seasonal and grid-scale (25 m2) spatially varying processes may overlook critical interactions that influence the lateral extent and overall morphological development of salt marshes. Therefore, this study underscores the need to integrate seasonal dynamics, species diversity, and below-ground biomass variability into biogeomorphological models to enhance predictive accuracy. This approach provides a more comprehensive understanding of the large-scale, long-term consequences of seasonal and spatiotemporally varying vegetation processes, which is essential for informing conservation and management strategies under changing climatic conditions. • Short-term dynamics are crucial for accurate long-term marsh development models. • The stabilizing effect of below-ground biomass influences marsh biogeomorphology. • Seasonal vegetation growth and wave conditions shape long-term marsh development. • Pioneer species introduction impacts vegetation stability and marsh morphology. [ABSTRACT FROM AUTHOR]

• 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]

There is a large uncertainty regarding the direction and magnitude of projected changes in the pattern and quantity of precipitation in future climate change scenarios. As changes in precipitation are likely to greatly impact plant diversity and biomass in desert ecosystems, we undertook a water addition/exclusion experiment to quantify the responses of plant diversity and biomass. To quantify the short-term impacts of changing the quantity of precipitation on plant species diversity and productivity in a desert steppe ecosystem. A simulated precipitation manipulation (addition and exclusion) experiment was made with four treatments: precipitation decreased by 50% (P-50%), precipitation increased by 50% (P+50%), precipitation increased by 100% (P+100%) and natural precipitation (Control). The richness of annual and biennial species was related to treatment; above-ground biomass increased in dry years in the P+100% treatment. Water addition had no statistically significant impacts on below-ground biomass. Increase in above-ground biomass with added precipitation in a drought year was mainly contributed by perennial grasses, suggesting that, from a management point of view, perennial grasses should be the focus of mitigation of projected future precipitation changes. [ABSTRACT FROM AUTHOR]

Fire is a fundamental ecological factor in savannas because it affects vegetation dynamics and ecosystem functioning. However, the effects of fire on below‐ground compartments, including biomass and root traits, and their regeneration remain poorly understood. In this study, we assess the variation of above‐ and below‐ground plant components along fire‐history gradients in Brazilian open savannas and investigate whether changes in vegetation and soil properties are associated with the responses of below‐ground biomass and root traits.The study was conducted in eight sampling areas of open savanna (campo sujo, i.e. vegetation having low woody cover) within the Cerrado (Brazilian savannas), located along a gradient of time since the last fire (1–34 years); the number of fires that occurred within the past 34 years (0–9 fires) varied by sampling area. In each sampling area, we measured above‐ and below‐ground biomass, root depth distribution, root functional parameters and nutrient levels in the upper soil layers (0–10 cm).Rapid recovery of above‐ground live biomass after a fire was primarily due to resprouting of graminoids. This recovery was associated with an increase in absorptive root biomass in the upper soil layer in the most recently burnt sites, whereas root biomass was unaffected in deeper layers. Root parameters remained constant regardless of fire history but responded to variations in vegetation structure and soil properties. Specific root length (SRL) decreased with K, Mg2+, Al3+, N and C and increased with P concentration. In contrast, root tissue density (RTD) and absorptive root proportion were negatively correlated with soil P. RTD was strongly associated with the above‐ground biomass of graminoids. Soil texture impacted the root system: the proportion of absorptive roots increased with fine sand content in the soil, inversely to transport root biomass. The relationship between fire and soil properties was insignificant.Synthesis. In savannas, fire stimulates absorptive root biomass in response to the higher demand for below‐ground resources. This response is correlated with shoot regrowth after a fire. Variations in morphological root parameters are not directly associated with fire history; instead, they reflect differences in soil chemistry, especially soil P and graminoid biomass changes. [ABSTRACT FROM AUTHOR]

The mangrove ecological services as carbon sinks and storage are very useful in the efforts to mitigate global warming and climate change. In this study, the above and below-ground biomass, carbon stock, as well as carbon sequestration by the mangroves in Demta Bay, Papua Province, Indonesia were estimated. Allometric equations were used to determine the mangrove biomass in 36 observation plots. The biomass value was used to determine carbon stock and estimate carbon sequestration. Nine mangrove species were found in Demta Bay, with the contribution of mangrove species to biomass (AGB and BGB) in the following order: Rhizophora apiculata > Rhizophora mucronata > Bruguiera gymnorhiza > Bruguiera cylindrica > Heritiera Littoralis > Xylocarpus molucensis > Rhizophora stylosa > Avicennia marina > Sonneratia caseolaris. The average mangrove biomass was estimated at 174.20 ± 68.14 t/ha (AGB = 117.62 ± 45.68 t/ha and BGB = 56.58 ± 22.49 t/ha). The carbon stocks in mangroves at the Ambora site were higher than the Tarfia and Yougapsa sites, averaging 123.57 ± 30.49 t C/ha, 81.64 ± 25.29 t C/ha, and 56.09 ± 39.03 t C/ha, respectively. The average carbon stock in the mangrove ecosystem of Demta Bay is estimated at 87.10 ± 34.07 t C/ha or equivalent to 319.37 ± 124.92 t CO2 e/ha. The results of this study indicate that the mangrove ecosystem in Demta Bay stores quite high carbon stocks, so it is necessary to maintain it with sustainable management. Therefore, climate change mitigation is not only done by reducing the carbon emission levels but also needs to be balanced by maintaining the mangrove ecosystem services as carbon sinks and sequestration. [ABSTRACT FROM AUTHOR]

The shea tree, Vitellaria paradoxa, shields people, crops and livestock in West African parkland agroforestry systems from climate variability. Accurate estimates of accumulated biomass of such key species may support ways to secure financial incentives within global climate policies. In this quest, variation in allometric relations used for biomass (carbon stock) estimates on the basis of stem diameter matters, but parameters a and b of the standard format (AGB = a Db; AGB = aboveground biomass, D = stem diameter) are correlated and are directly related to tree shapes. Functional branch analysis (FBA) allows non-destructive derivation of allometrics. For Koutiala and Yanfolila shea populations empirical branching parameters were scale-independent, matching FBA assumptions. Allometry (AGB = 169 (D/20)2.64 and AGB = 146 (D/20)2.65, kg tree−1) implied 22%, 16% and 11% larger vegetative aboveground biomass in Koutiala than in Yanfolila at stem diameters (D) of 10, 20 and 32 cm, respectively. Below-ground biomass predictions (BGBi = 8.73 (Di/10)2.35 and BGBi = 8.16 (Di/10)2.38, kg per proximal root) differed − 6% and − 15% for root diameters Di of 10 and 32 cm, respectively. On a dry weight basis, the shoot:root ratio was 2.7 and 2.9, respectively for the two sites. Stand-level above-and below-ground carbon stocks in Koutiala (2.16 ± 0.44 and 0.8 ± 0.15 Mg C ha−1) were not significantly different from those in Yanfolila (3.21 ± 0.60 and 1.26 ± 0.21 Mg C ha−1), respectively. Further research is required to include (potential) fruit production to the plant architectural model. [ABSTRACT FROM AUTHOR]

Aims: More sustainable agricultural systems, which contribute to C sequestration and biological N fixation, require accurate quantification of plant C and N inputs into soils. This has to be conducted under field conditions, as there are serious shortcomings to pot-based experiments, which have dominated studies on rhizodeposition estimation in the past. Therefore, amounts of below-ground plant C, N, and especially the rhizodeposition of peas were quantified in the field more accurately, with particular emphasis on their transfer into different soil compartments during vegetation. Methods: Pea (Pisum sativum L.) plants were labelled with multiple pulses of 13C-glucose and 15N urea using the cotton wick method. Plants were harvested at four dates depending on plant development. Representative soil samples were taken at harvest with a special drilling tool, considering the spatial distribution of pea roots. Results: Our results indicate that the quantity of C and N rhizodeposition did not change between flowering and maturity. About one third of the C and N rhizodeposits were present in microbial biomass and extractable C or the inorganic N pool of soil. When comparing this field study to a former pot experiment, a higher root-to-shoot ratio was detected; also the rhizodeposition-to-root ratio was altered in the field, questioning the assumption that results from pot experiments can be transferred to field conditions. Conclusions: Due to a higher below-ground C (BGC) and N (BGN) input compared to pot experiments, studies aiming at quantifying BGC and BGN input will have to be conducted under field conditions. [ABSTRACT FROM AUTHOR]

Highlights • Among-site variation in the total fine root biomass was not explained by latitude. • Fine root density increased in the organic layer towards the north. • The future climate may shift fine roots from the organic layer to the mineral soil. Abstract The geographical patterns in the distribution of fine root biomass (FRB) and in the contribution of fine roots to below-ground nitrogen and carbon stocks are poorly documented. Here, we examined FRB and the ecological factors that govern it, along a 1000 km long latitudinal gradient in unmanaged mixed boreal forests in North-East Europe. We sampled fine roots (diameter ≤2 mm; trees and field layer vegetation combined) twice per growing season in 2015 and 2016 from ten sites spaced one degree of latitude between 60°N (near St. Petersburg) and 69°N (near Murmansk, Russia). We separated living fine roots. The roots were dried and weighed; tissue carbon and nitrogen concentrations were measured. The obtained values were correlated with climatic, plant community and soil characteristics. Among-site variation in the total FRB and carbon and nitrogen concentrations were not explained by latitude or by climatic, plant community or soil characteristics. However, fine root density in the organic layer increased towards the north. The more superficial root system in the north than in the south may indicate a poleward increase in the vulnerability of boreal forests to abiotic risks (forest fires, drought). Our results suggest that the future climate may shift fine roots as well as carbon and nitrogen cycling from the organic layer to mineral soils, thereby increasing the volume of soil utilized by fine roots for water and nutrient uptake. [ABSTRACT FROM AUTHOR]

Understanding carbon (C) stocks or biomass in forests is important to examine how forests mitigate climate change. To estimate biomass in stems, branches and roots takes intensive fieldwork to uproot, cut and weigh the mass of each component. Different models or equations are also required. Our research focussed on the dry tropical Zambezi teak forests and we studied their structure at three sites following a rainfall gradient in Zambia. We sampled 3558 trees at 42 plots covering a combined area of 15ha. Using data from destructive tree samples, we developed mixed-species biomass models to estimate above ground biomass for small (<5 cm diameter at breast height (DBH, 1.3 m above-ground)) and large (≥5 cm DBH) trees involving 90 and 104 trees respectively, that belonged to 12 species. A below-ground biomass model was developed from seven trees of three species (16–44 cm DBH) whose complete root systems were excavated. Three stump models were also derived from these uprooted trees. Finally, we determined the C fractions from 194 trees that belonged to 12 species. The analysis revealed that DBH was the only predictor that significantly correlated to both above-ground and below-ground biomass. We found a mean root-to-shoot ratio of 0.38:0.62. The C fraction in leaves ranged from 39% to 42%, while it varied between 41% and 46% in wood. The C fraction was highest at the Kabompo site that received the highest rainfall, and lowest at the intermediate Namwala site. The C stocks varied between 15 and 36 ton C ha −1 and these stocks where highest at the wetter Kabompo site and lowest at the drier Sesheke site. Our results indicate that the projected future rainfall decrease for southern Africa, will likely reduce the C storage potential of the Zambezi teak forests, thereby adversely affecting their mitigating role in climate change. [ABSTRACT FROM AUTHOR]

N and P concentrations and their ratios were determined for 132 foliar and 120 below-ground biomass (BGB) samples obtained at 132 sites along the 4500 km Chinese Grassland Transect (CGT) across the Inner Mongolian and Qinghai-Tibet Plateaus. Patterns of foliar and BGB N, P and their ratio (N/P) at the community level were related to altitude, temperature, and precipitation gradients. Also, patterns of relative N and P foliar and BGB concentrations were determined (N, foliar N/BGB N; P, foliar P/BGB P). The relationship between foliar N concentrations and mean annual temperature (MAT) was negative, agreeing with the Temperature-Plant Physiological hypothesis, whereas BGB N decreased with decreasing MAT, supporting the Biogeochemical hypothesis. Patterns of BGB N varying with altitude, MAP and MAT differed from the patterns for leaf N, which may indicate differences in nutrient allocation and utilization by leaves and BGB. N and P may reflect trade-offs by plants for N and P in leaves and BGB. For the entire CGT, N and P increased as altitude increased. N was positively related with MAP but negatively related with MAT, while P showed no correlations with MAP and MAT. Results suggest that ecological stoichiometry at the community level is similar to that at the species level. Strategies of nutrient utilization by leaves and BGB are indicated to be different, and abiotic environmental conditions could influence the stoichiometric characteristics and nutrient allocation to leaves and BGB. [ABSTRACT FROM AUTHOR]

Eucalyptusstands in semi‑arid areas may contribute to enhance carbon (C) stocks in both biomass and soil. However, the limited information available is mainly focused on short‑rotation plantations. In this study, the above‑ and below‑ground C pools in five 50‑year‑oldEucalyptus camaldulensisDehnh. stands planted on Miocenic evaporitic deposits in Sicily, Italy, with a xeric and thermic pedoclimate, were measured. Above‑ground biomass was determined by partitioning and weighing branches, stem and leaves. Below‑ground C pools included the determination of litter, root biomass, and soil organic and inorganic C.In terms of the above‑ground biomass, theE. camaldulensisstand accumulated on average 116 Mg ha−1 corresponding to 55 Mg C ha−1.Below‑ground biomass consisted mainly of larger roots, followed by fine and medium roots (33 Mg ha−1 corresponding to 14 Mg C ha−1). Litter accumulation on the soil surface accounted for 13 Mg ha−1 corresponding to 5 Mg C ha−1. The amount of C stored in soil was 554 Mg C ha−1, of which 75% was in organic form. AlthoughE. camaldulensisis planted extensively throughout the Southern Hemisphere and tropics where it is managed over short rotations (c. 2–4 years), the results obtained from this study make this species important in terms of future afforestation planning for longer rotations due to its potential to sequester C, particularly in the below‑ground components. [ABSTRACT FROM AUTHOR]

Non-destructive assessment of root systems is important in order to understand and optimise the potential of resource capture and allocation by the plant. We studied the relationships between electrical capacitance (EC) and the below- and above-ground biomass of willows. Cuttings of Salix viminalis × Salix schwerinii cv. Olof were maintained in pots and root development was followed up using a portable capacitance meter over the course of 2.5 months. Pot observations were compared with excavation of two-year-old established trees. A strong significant linear relationship (R2 = 0.81, p < 0.001) was obtained between EC and root biomass (dry weight [DW]) for the pot experiment. EC also showed good correlations with stem and leaf biomass, as well as with stem height. In the excavated willow trees, there was a strong logarithmic relationship between EC and root biomass (R2 = 0.66, p < 0.001). These results suggest that EC is a good estimator of below-ground biomass in willow and may become useful in screening varieties for differences in root biomass traits, especially in distinguishing below-ground resource allocation at an early stage. [ABSTRACT FROM AUTHOR]

Aim To investigate large-scale patterns of above-ground and below-ground biomass partitioning in grassland ecosystems and to test the isometric theory at the community level. Location Northern China, in diverse grassland types spanning temperate grasslands in arid and semi-arid regions to alpine grasslands on the Tibetan Plateau. Methods We investigated above-ground and below-ground biomass in China's grasslands by conducting five consecutive sampling campaigns across the northern part of the country during 2001–05. We then documented the root : shoot ratio (R/S) and its relationship with climatic factors for China's grasslands. We further explored relationships between above-ground and below-ground biomass across different grassland types. Results Our results indicated that the overall R/S of China's grasslands was larger than the global average (6.3 vs. 3.7). The R/S for China's grasslands did not show any significant trend with either mean annual temperature or mean annual precipitation. Above-ground biomass was nearly proportional to below-ground biomass with a scaling exponent (the slope of log–log linear relationship between above-ground and below-ground biomass) of 1.02 across various grassland types. The slope did not differ significantly between temperate and alpine grasslands or between steppe and meadow. Main conclusions Our findings support the isometric theory of above-ground and below-ground biomass partitioning, and suggest that above-ground biomass scales isometrically with below-ground biomass at the community level. [ABSTRACT FROM AUTHOR]

Data on the distribution of root biomass are critical to understanding the ecophysiology of vegetation communities. This is particularly true when models are applied to describe ecohydrology and vegetation function. However, there is a paucity of such information across continental Australia. We quantified vertical and horizontal root biomass distribution in a woodland dominated by Angophora bakeri and Eucalyptus sclerophylla on the Cumberland Plains near Richmond, New South Wales. The site was characterised by a duplex (texture contrast) soil with the A horizon (to 70 cm) consisting of loamy sand and the B horizon (to > 10 m) consisting of sandy clay. The topsoil had a smaller bulk density, a smaller water holding capacity but a larger organic component and a larger hydraulic conductivity in comparison to the subsoil. Root biomass was sampled to 1.5 m depth and declined through the soil profile. Whilst total biomass in the B horizon was relatively small, its contribution to the function of the trees was highly significant. Coarse roots accounted for approximately 82% of the root mass recovered. Lateral distribution of fine roots was generally even but coarse roots were more likely to occur closer to tree stems. Variation in tree diameter explained 75% of the variation in total below-ground biomass. The trench method suggested the belowground biomass was 6.03 ± 1.21 kg m−2 but this method created bias towards sampling close to tree stems. We found that approximately 68% of root material was within a 2 m radius of tree stems and this made up 54% of the total number of samples but in reality, only approximately 5 to 10% of the site is within a 2 m radius of tree stems. Based on these proportions, our recalculated belowground biomass was 2.93 ± 0.59 kg m−2. These measurements provide valuable data for modeling of ecosystem water use and productivity. [ABSTRACT FROM AUTHOR]

Abstract: Regression models relating variables derived from airborne laser scanning (ALS) to above-ground and below-ground biomass were estimated for 1395 sample plots in young and mature coniferous forest located in ten different areas within the boreal forest zone of Norway. The sample plots were measured as part of large-scale operational forest inventories. Four different ALS instruments were used and point density varied from 0.7 to 1.2 m−2. One variable related to canopy height and one related to canopy density were used as independent variables in the regressions. The statistical effects of area and age class were assessed by including dummy variables in the models. Tree species composition was treated as continuous variables. The proportion of explained variability was 88% for above- and 85% for below-ground biomass models. For given combinations of ALS-derived variables, the differences between the areas were up to 32% for above-ground biomass and 38% for below-ground biomass. The proportion of spruce had a significant impact on both the estimated models. The proportion of broadleaves had a significant effect on above-ground biomass only, while the effect of age class was significant only in the below-ground biomass model. Because of local effects on the biomass–ALS data relationships, it is indicated by this study that sample plots distributed over the entire area would be needed when using ALS for regional or national biomass monitoring. [Copyright &y& Elsevier]

Question: Pollution and eutrophication of surface water is increasingly a problem in agricultural landscapes. Do intact (relatively undisturbed) and degraded forests differ in seasonal nutrient storage and therefore potential to ameliorate nutrient pollution? Location: United States, Midwestern region. Methods: We used three sets of paired plots, where intact plots were located close to disturbed woodlands. Herbaceous perennials located in eight 0.25 m² quadrats in the plots were harvested (in spring and mid-summer), dried, separated into above- and below-ground plant parts, and weighed to determine biomass. Nitrogen, phosphorus and potassium content of the plant tissues were then determined, and these data combined with biomass to estimate nutrient storage. Results: In spring, intact sites had 62% greater above-ground biomass than disturbed sites and 75% greater below-ground biomass. In summer, below-ground biomass of intact plots was still much greater than that of disturbed plots (73 percent), but above-ground biomass was similar. Nutrient tissue concentration generally did not differ, nor did soil nutrient levels. The disturbed sites were largely missing one group of species, the spring ephemerals, and this accounted for the difference in biomass and nutrient storage between sites. Conclusions: Relatively undisturbed woodlands in our study had a much greater capacity to store nutrients, and therefore ameliorate nutrient pollution, in early spring. This is significant because spring is also the time of highest potential leaching of nutrients into surface water. [ABSTRACT FROM AUTHOR]

Fine roots (<2 mm) are very dynamic and play a key role in forest ecosystem carbon and nutrient cycling and accumulation. We reviewed root biomass data of three main European tree species European beech, (Fagus sylvatica L.), Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.), in order to identify the differences between species, and within and between vegetation zones, and to show the relationships between root biomass and the climatic, site and stand factors. The collected literature consisted of data from 36 beech, 71 spruce and 43 pine stands. The mean fine root biomass of beech was 389 g m-2, and that of spruce and pine 297 g m-2 and 277 g m-2, respectively. Data from pine stands supported the hypothesis that root biomass is higher in the temperate than in the boreal zone. The results indicated that the root biomass of deciduous trees is higher than that of conifers. The correlations between root biomass and site fertility characteristics seemed to be species specific. There was no correlation between soil acidity and root biomass. Beech fine root biomass decreased with stand age whereas pine root biomass increased with stand age. Fine root biomass at tree level correlated better than stand level root biomass with stand characteristics. The results showed that there exists a strong relationship between the fine root biomass and the above-ground biomass. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine the effect of spatial pattern on corn above- and below-ground biomass, grain yield, weed above-ground biomass and soil water and photosynthetically active radiation (PAR) dynamics. Field studies were conducted in 2003 and 2004. Three corn hybrids with two spatial pattern (square and rectangular) under weed-free and weedy conditions were tested. Corn grain yield was greater in the square than in the rectangular pattern. This increase was related to better resources use while reducing the competition from weeds. Early in the growing season, there was greater moisture content in the intrarow at square pattern while a lower soil water content was observed at maturity. Conversely, the square pattern registered lower soil water content during the whole corn growing season in the interrow. This soil water profile was an outcome of the uniform corn below-ground biomass distribution. A greater PAR interception with a lower weed above-ground dry matter was obtained in square plant arrangement. The use of uniform spatial pattern appeared as an interesting alternative to increase both the grain yield potential and the corn suppressive ability against weeds in dry-land Argentinean production systems. [ABSTRACT FROM AUTHOR]

A new Sim-CYCLE grazing model has been obtained by combining a grazing model (Seligman et al. 1992, Ecol. Model. 60: 45–61) with the Sim-CYCLE model (Ito and Oikawa 2002, Ecol. Model. 151: 143–176). The new model has been validated against a set of field data obtained at Kherlen Bayaan-Ulaan (KBU) grassland. On the basis of the model, the root responses to grazing of KBU grassland have been studied under different conditions of stocking rates and precipitation. Model results indicate that both below-ground biomass (BB) and below-ground net primary production (BNPP) generally decrease with increasing stocking rate. However, if stocking rate is not higher than 0.7 sheep ha−1, a sustainable state of the grassland ecosystem can be achieved after about 100 years, which suggests that the maximum sustainable stocking rate at KBU should be 0.7 sheep ha−1. At the sustainable state, the maximum BB in a year is about 11 Mg DM ha−1 under non-grazing condition, 5 Mg DM ha−1 under 0.4 sheep ha−1 stocking rate, and 4 Mg DM ha−1 under 0.7 sheep ha−1 stocking rate; the BNPP is 1.3 Mg DM ha−1 year−1 under non-grazing condition, and 0.6 Mg DM ha−1 year−1 under 0.4 sheep ha−1 stocking rate, and 0.4 Mg DM ha−1 year−1 under 0.7 sheep ha−1 stocking rate. Ratio of non-assimilation organ to assimilation organ (C/F) increases with increasing stocking rate. The C/F ratio is 10.99 under non-grazing conditions, and 12.11 under 0.7 sheep ha−1 stocking rate. Root turnover rate decreases with increasing stocking rate. The rate is 12% each year under non-grazing conditions, and 11% each year under 0.7 sheep ha−1 stocking rate. In addition, the effect of grazing on the grassland ecosystem under different scenarios of precipitation is also analyzed. Both BB and BNPP increase with increased precipitation, and vice versa. When precipitation is set to be 10% higher than the averaged from 1993 to 2002, the maximum sustainable stocking rate is 0.8 sheep ha−1, and when the precipitation is set to be 15% lower than the averaged, the maximum sustainable stocking rate is 0.6 sheep ha−1. [ABSTRACT FROM AUTHOR]

Abstract: Comparisons were made of three different 15N-feeding techniques, leaf, petiole and stem feeding, to identify the most efficient technique for labelling above-and below-ground plant biomass under controlled environment conditions. 15N-urea (0.5%, 10 atom % excess 15N) was applied to chickpea (Cicer aritenium var. ICCV 5003) plants twice during early growth. Leaf feeding was found to be the most efficient in terms of 15N-solution uptake (5.9ml 48h−1) and 15N-enrichment at harvest, with 0.95, 0.41, 0.79, 0.67 and 0.22 atom % excess 15N in the leaves, stems, grain, grain straw and clean root fractions, respectively. Solution uptake was low in the second stem feeding event due to blockage of the drilled hole, resulting in low 15N-enrichment of leaves (0.29 atom % excess 15N). Although petiole feeding resulted in more even relative enrichments among plant parts our results highlight the usefulness of leaf 15N-feeding to estimate below-ground plant N and to trace the long-term fate of plant-derived N within the soil. [Copyright &y& Elsevier]

A chronosequence of Gmelina arborea Roxb. stands ranging from 1 to 6 years old was measured to document changes in growth, biomass and nutrient (N, P and K) contents for three red lateritic sites in Chhattisgarh, India. The stand''s density, survival and growth parameters (DBH, total height, crown diameter and number of branches) varied significantly with age and site. The number of stems was highest (789 trees/ha) in a 1-year-old plantation at site 3 (Kusumi) and lowest (724 trees/ha) in a 6-year-old stand at site 2 (Anandgoan). Allometric equations for stem wood, branches, leaves and roots to tree diameter at breast height were developed to estimate above ground and below ground tree biomass. The total biomass ranged from 3.9 Mg ha−1 in 1-year-old to 53.7 Mg ha−1 in 6-year-old stand. The stem wood contributed from 55.3% (site 3) to 56.3% (site 1), branch wood from 18.3% (site 2) to 19.8% (site 3), roots from 17.9% (site 3) to 18.5% (site 2) and foliage from 6.6% (site 2) to 7.0% (site 3) of the total biomass. The growth and biomass production were poor from establishment to 3 years age and it increased by 1.5–2 times as the plantation aged from 4–6 years. Nutrient accumulation in tree biomass increased with stand age, following the pattern of biomass accumulation. The total nitrogen accumulation in 6-year-old stands at three sites ranged from 212.9 to 279.5 kg ha−1 with a mean annual storage of 238.4 kg ha−1 and total K ranged from 170.8 to 220.5 kg ha−1 with a mean annual storage of 189.9 kg ha−1. Phosphorous storage was lowest which ranged from 15.0 to 19.6 kg ha−1 with a mean storage of 16.8 kg ha−1. The organic matter and nutrients in the soils improved significantly after 6 years of planting. Available N enhanced by 14.9%, 12.0% and 11.3%, K by 10.0%, 9.1% and 10.6%, whereas phosphorous declined by 2.6%, 23.0% and 20.0%, respectively, at soil depths of 0–20, 21–40 and 41–60 cm. The paper discusses the implications of whole tree harvest at 6 years age for fire/pulpwood. [Copyright &y& Elsevier]

Certainty over warming-induced biomass accumulation is essential for addressing climate change. However, no previous meta-analysis has investigated this accumulation across the whole of China; also unclear are the differences between herbaceous and woody species and across plant phylogeny, which are critical for corresponding re-vegetation. We extracted data from 90 field-based experiments to reveal general patterns and driving factors of biomass responses all over China. Based on traditional meta-analyses, a warmer temperature significantly increased above- (10.8%) and below-ground (14.2%) biomass accumulation. With increasing warming duration (WarmD) and plant clade age, both above-ground and below-ground biomass showed significant increases. However, for herbaceous versus woody plants, and the whole community versus its dominant species, responses were not always constant; the combined synergies would affect accumulative response patterns. When considering WarmD as a weight, decreases in total above-ground biomass response magnitude were presented, and the increase in below-ground biomass was no longer significant; notably, significant positive responses remained in tree species. However, if phylogenetic information was included in the calculations, all warming-induced plant biomass increases were not significant. Thus, it is still premature to speculate whether warming induces biomass increases in China; further long-term experiments are needed regarding phylogeny-based responses and interspecies relations, especially regarding woody plants and forests. [ABSTRACT FROM AUTHOR]