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Tropical forests play an important role in ecosystem services, yet anthropological activities have changed the ecological conditions. Thus, this research was designed to reveal the species richness and diversity in secondary forests, including the lifeform alteration. The 50 perpendicular plots were placed in both forests and distributed 25 for each. The study revealed that the secondary forest represents a stage of ecological succession in which species richness and diversity decreased. Additionally, the composition of life forms in the secondary forest changed, with dominant herbs indicating more dynamic vegetation due to shifting ecological conditions. Species classified as Threatened have disappeared due to human activities in the forest. However, the secondary forest has provided a habitat for certain species, including those with conservation status, such as Threatened or Extinct, to thrive and colonize, where approximately 15.7% of species exclusively thrive in secondary forests, including Antiaropsis uniflora C.C.Berg. Therefore, to promote sustainable forest management, this study suggests monitoring the species in secondary forests, particularly since the use of forests has traditionally been determined by local communities, including in restricted forest areas. Moreover, the local government could officially designate traditional forest use, thereby allowing restricted forests to be conserved as old-growth forests. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hurricanes are extreme climatic events frequently affecting tropical regions such as the tropical dry forests (TDFs) in Mexico, where its frequency/intensity is expected to increase toward the year 2100. To answer how resistant is a Mexican tropical dry forest to a high-intensity hurricane, and if its degree of resistance was mediated by its conservation degree, we evaluated the effect of a category 4 hurricane over the tree community, soil nutrients, and soil enzymatic activity in two contrasting TDF ecosystems: Old-Growth Forest (OGF) and Secondary Forest (SF). In general, vegetation richness and diversity showed very high resistance one year after the hurricane, but several structural attributes did not, especially in the OGF where the tree mortality related to vegetation structure and spatial distribution of individuals was higher. Then, in the short term, SF vegetation appeared to be more resistant, whereas the OGF, with more biomass to lose, appeared to be more vulnerable. Conversely, most soil attributes showed low resistance in both stages, but especially in SF which could face more severe nutrient limitations. The response of TDF to high-intensity hurricanes, in terms of above- and belowground processes, was in part dependent on its disturbance level. Moreover, an increase in the intensity/frequency of hurricanes could lead this TDF toward a high nutrient limitation (especially by phosphorus) for the plants and consequently toward a loss of soil functioning, especially in the SF. This eventually could produce a severe degradation in fundamental attributes and functions of the ecosystem. [ABSTRACT FROM AUTHOR]

The tropical forest plays an important role in ecosystem services, yet anthropological activities have changed the ecological conditions. Thus, this research was designed to reveal the species richness and diversity in secondary forests, including lifeform alteration. The 50 perpendicular plots were placed in both forests, with 25 for each. The study revealed that the secondary forest represents a stage of ecological succession in which species richness and diversity decreased. Additionally, the composition of life forms in the secondary forest changed, with dominant herbs indicating a more dynamic vegetation due to shifting ecological conditions. Species classified as Threatened have disappeared due to human activities in the forest. However, the secondary forest has provided a habitat for certain species, including those with conservation status, such as Threatened or Extinct, to thrive and colonize. Approximately 15.7% of species exclusively thrive in secondary forests, including Antiaropsis uniflora C.C.Berg. Therefore, to promote sustainable forest management, this study suggests monitoring the species in secondary forests, particularly since the use of forests has traditionally been determined by local communities, including in restricted forest areas. Moreover, the local government could officially designate traditional forest use, thereby allowing restricted forests to be conserved as old-growth forests.

Biological soil crusts are important components of dryland ecosystems, showing variations in appearance, morphology, and function across developmental stages. However, the methods for recording biocrust developmental stages have not been simplified and standardized. In this study, three developmental grades for both cyanobacterial crust and moss crust were defined based on visual indicators such as color, thickness, and moss height. A field survey was conducted across three precipitation regions in northern China, during which the developmental grades of cyanobacterial and moss crusts were visually recorded. Key biocrust developmental indicators, including shear strength, penetration resistance, coverage, chlorophyll a content, and bulk density were measured for each grade. The results showed that both cyanobacterial and moss crusts could be effectively classified into three developmental grades based on these indicators, with a 90% concordance between the measured indicators and the defined grading method. This finding validated that the method could accurately reflect biocrust developmental stages while simplifying field recordings. Developmental indicators in various grades of cyanobacterial and moss crusts showed a moderate (30% < CV < 100%) to strong (CV > 100%) variation, highlighting the importance of environmental heterogeneity at the regional scale. Moreover, the grading method proved effective across varying spatial scales, highlighting its broad applicability. However, its validation across the comprehensiveness of target objects and the geographical scope remains limited. Future research should focus on expanding the grading method to include lichen crust, refining it across diverse ecosystems, and exploring the integration of advanced technologies such as hyperspectral imaging and machine learning to automate and improve the classification process. This study provides a simple and effective grading method for visually recording the developmental stages of biological soil crusts, which is useful for ecological research and field applications.

Background and aims: Insight for vegetation restoration in karst mountains could come from understanding the methods by which communities are built along a successional chronosequence. We integrated species diversity, phylogenetic structure, and functional trait diversity to investigate the mechanisms governing community assembly along a successional chronosequence in the northern tropical karst mountains, South China. Methods: Five successional sequences, including grassland, shrubland, young forest, middle-aged forest, and primary forest, were selected in the northern tropical karst mountains using the space-for-time substitution method. The relationships between species diversity and environmental variables (elevation, slope degree and rock exposed rate) were investigated using redundancy analysis and variance partitioning methods. Results and discussion: Our results showed that as succession progressed, species and phylogenetic diversity showed an increasing trend, then a decreasing trend, with the maximum value occurring in young forests, which displayed the optimum curves over the successional gradient. In terms of functional diversity, shrubland, and young forest had significantly higher functional richness than grassland and middle-aged forest, and grassland and young forest had significantly higher quadratic entropy coefficients than primary forest. The vegetative community changed in phylogenetic structure from clustering in the early stages of succession to diverging in the late stages.In contrast, the leaf thickness density decreased as succession progressed, suggesting that the young forest vegetation had the highest resource acquisition ability and utilization rate as the successional progressed. Additionally, the chlorophyll content, leaf thickness, and leaf area showed a first increased then decreased trend as successional progressed. Conclusions: Our results suggest that due to harsher soil conditions, the vegetation in early successional stage was dominated by environmental filtering (i.e., limitation of environmental resources), whereas the vegetation in late successional stage was governed by competitive exclusion (i.e., species competition). Our findings can guide plants conservation and ecological restoration in the tropical karst regions. [ABSTRACT FROM AUTHOR]

Nebkhas play a tremendous role in maintaining the ecological functions of deserts and in slowing land desertification processes. Numerous nebkhas are distributed in the northwestern edge of the Ulan Buh desert, Nitraria tangutorum nebkhas are the most typical dunes in this area. However, our knowledge of the effect of those factors on the succession of nebkhas, including their succession in different sandy land types, is limited. The goal of this study was to reveal their factors influencing the morphological characteristics of N. tangutorum nebkhas in different sandy land types (shifting sandy land, semi-fixed sandy land, and fixed sandy land) in the Ulan Buh desert. Our results showed the densities of N. tangutorum nebkhas were 34, 51, and 77 dunes per ha in the shifting, semi-fixed, and fixed sandy lands, respectively. The density of N. tangutorum nebkhas gradually increased and N. tangutorum nebkhas started to degenerate with the increasing fixation of sandy land. The successional stage had significant effects on all the morphological characteristics, and sandy land types had significant effects on the length (L), height (H), volume (V), horizontal scale (D) and ratio of width to height (H/W). Almost all of the morphological parameters of N. tangutorum nebkhas were correlated at different successional stages, indicating a strong interrelationship among the morphological parameters of nebkhas. The successional stages of N. tangutorum nebkhas had significant effects on the density of branch (M), height (h), coverage (C), deadwood rate (DR), and length of new branches (LB) of the N. tangutorum shrub. The M, h, C, and LB first increased and then decreased, and DR increased with the succession of N. tangutorum nebkhas. These results indicated that we should focus on nebkhas succession to ensure the ecological stability of oases in a dessert. [ABSTRACT FROM AUTHOR]

In the southeastern Peruvian Amazon, small-scale and artisanal gold mining has become a common activity and represents one of the greatest threats to forests. The study evaluated the natural regeneration of vegetation and the physicochemical properties of the soil for a chronosequence in Madre de Dios (Peru). Fourteen plots of 250 m2 were installed, distributed across areas with abandonment times varying from 2 to 19 years. All stems with a diameter at breast height ≥ 1 cm in each plot were recorded and classified according to size categories (saplings, poles, and trees). We recorded 1023 individuals distributed in 80 species and 27 families. The most abundant families were Fabaceae, Annonaceae and Euphorbiaceae. Inga thibaudiana, Ochroma pyramidale, and Cecropia membranacea were present in all three size categories. The plots exhibited high heterogeneity, with medium diversity and very low species dominance. The dominant dispersal syndrome was zoochory (>60%). Pioneer species dominated initial and secondary succession with a higher abundance and species richness, decreasing considerably in late secondary succession. The soils exhibited a sandy loam texture, moderate to strongly acidic pH, poor nutrients, and limited organic matter. Soil alterations due to mining will therefore lead to slow natural regeneration.

Fine roots have been hypothesized to be 'leaves underground' in terms of vascular network, but this hypothesis has rarely been tested within the framework of metabolic scaling theory (MST). We measured average fine‐root (diameter < 1 mm) mass (M), surface area (A), volume (V), diameter (D) and length (L) for 216 soil cores from 24 plots across four successional stages in tropical forests of Xishuangbanna (southwest China), and examined eight scaling relationships between these variables at the individual root scale. We tested whether fine‐root allometries conformed to MST's model for leaf (MSTl) or model (MSTw) for woody organs (e.g. trunk). We also assessed the relative effects of environmental factors, tree size, species composition and diversity, and stand structural factors on allometric relationships using structural equation models (SEMs). Our results showed that: 1) fine‐root scaling exponents rarely conformed to MSTl's predictions. 2) The scaling exponents between fine‐root M, A, V and D all conformed to MSTw's predictions in later successional forests, but showed greater deviation towards early successional stage. 3) The scaling exponents associated with fine‐root length differed markedly from MSTw's predictions. 4) Changes of some fine‐root scaling exponents across successional stage were mainly affected by tree size or soil fertility, and species composition affected allometry only indirectly via tree size. Our results suggested that the allometries of individual fine roots largely conform to the scaling rules governing woody organs instead of leaves, probably because leaves are nearly two‐dimensional objects while the other two are three‐dimensional. We showed that MSTw can well predict some fine‐root allometries in later successional forests, suggesting great potential of utilizing MSTw to better estimate fine‐root biomass and productivity. However, the present MSTw still needs to be improved for predicting the scaling relationships concerning fine‐root length, and also for better quantifying allometric exponents in earlier successional forests. [ABSTRACT FROM AUTHOR]

Statement of problem. Due to the continuous variability of the forest regeneration process, patterns of indicator variables with membership in more than one successional stage may occur, making the classification of such stages a challenging and complex task. Purpose. This study aims at presenting a comparative analysis of artificial intelligence methods as an alternative for computer-aided classification of successional stages in subtropical Atlantic Forest. As a research hypothesis, the authors consider that a fuzzy inference system should provide the best performance due to its ability to deal with uncertainties inherent to complex processes. Material and methods. The analyses were carried out using a database of the forest inventory of Santa Catarina, Southern Brazil. The data are composed of 177 sampling units of subtropical Atlantic Forest (mixed ombrophilous forest), characterized according to eighth indicator variables verified from the field by experts. This database was employed to train several machine learning methods under a tenfold cross-validation process. The overall accuracy (θ) and kappa coefficient were used to compare the performance between FIS and neural networks, classifier committees and support vector machine. Then, to verify if the classification by the FIS differed from the one performed by experts, the Kappa index and a statistical significance analysis by Pearson’s χ 2 test were determined. The hypotheses were verified with two-way tests at a significance level (α) 0.05, for a test power (1-β) 0.8 and minimum expected effect size between medium (ρ = 0.3). Results. Statistical significance tests confirmed the hypothesis that FIS achieved the highest performance, with θ = 98.3% and a kappa value equal to 0.93 (almost perfect agreement) and showed no significant difference ( χ 2 = 0.047, p = 0.976) in comparison with the classification by experts. Conclusions. The use of FIS represents a promising alternative as a tool applicable for computer-aided classification of successional stages in subtropical Atlantic Forest. Practical implications. The results and conclusions should substantially impact the guidelines and decision-making process for deforestation authorizations and applicable compensation measures, which are based on the forest succession stage. [ABSTRACT FROM AUTHOR]

Tropical forests continue to suffer from various kinds of disturbances in the Anthropocene. An immediate impact of disturbances on forest ecosystems is the creation of numerous large and small canopy gaps, which dramatically affect forest structure and function. Yet, we know little about the effect of canopy gaps on forest successional trajectory. More specifically, the responses of seedlings from different successional stages to increased light intensity under large and small canopy gaps in understory remain unclear. In this study, dominant tree seedlings from early-, mid-, and late-successional stages were selected, respectively from a tropical montane forest in Hainan Island, China to study their growth rate, biomass and traits. Our results showed that the light condition under small canopy gaps (SG, 10–15% of full sunlight) and large canopy gaps (LG, 40–50% of full sunlight) induced greater increment of relative growth rates for seedlings from early- and mid-successional stages relative to that in late-successional stage. Both SG and LG also significantly increased photosynthesis rate, leaf area (LA), light saturation point (LSP), root mass ratio (RMR) and root: shoot ratio, but decreased specific leaf area (SLA) of seedlings across successional stages. Tree seedlings from the early-successional stage displayed the greatest decrease in leaf mass ratio, increase in LA, LSP, and RMR, in comparison to those from mid- and late- successional stages. Light condition and SLA were the most important factors for seedlings’ relative growth rate across successional stages. SLA connected the interaction between the light condition and successional stage on seedlings’ growth, thereby jointly explaining the 93% variation of seedlings’ growth, combining with area-based light saturated rate of CO2 assimilation. Our study highlights the distinct effect of disturbance-induced canopy gaps on seedling regeneration in the understory in tropical forest due to the variation of light intensity. We suspect that the seedlings from late-successional stage will recover relatively slow after disturbances causing canopy losses, which can have detrimental impacts on structure feature and successional trajectory in tropical forest, as well as forest-based ecosystem services.

We selected two forest stands of different successional stages in Shimentai National Nature Reserve in north Guangdong to reveal the forest structure and interspecific association in different successional stages. We used the chronosequence method to investigate the species composition, community structure, and interspecific associations of the canopy trees. We also used two-way cluster analysis, principal coordinate analysis, and the χ~2 test based on a 2×2 contingency table to analyze species distribution and interspecific associations of the canopy trees. The results showed that, with community succession, the total number of species in the community decreased, and the heliophilous plants with a low importance value gradually disappeared, while the importance value of shade-tolerant plants increased. In community Ⅰ（85 years of forest age）, 42.38% species pairs had positive associations, while 57.62% of the total species pairs had negative associations. Only 11 species pairs were found to have significant interspecific associations, accounting for 5.24% of the total, indicating a strong independence of species in the community. In community Ⅱ（65 years of forest age）, 25.32% of species pairs had positive associations, and 74.68% had negative associations, with significant interspecific associations found in 35.56% of the total species pairs. With the progress of succession, the proportion of species pairs with negative associations decreased, while the proportion of those with nonsignificant positive associations increased. These results demonstrate that forest trees in the communities tended to be relatively stable in coexistence with the succession progress, and community stability might be maintained by the improvement of tree species independence. [ABSTRACT FROM AUTHOR]

To achieve carbon neutrality in the face of climate change, accurately estimating forest carbon uptake is crucial. Environmental changes, such as temperature increases or precipitation fluctuations caused by climate change, can alter the growth responses of each species and act as a driver for changes in forest productivity. In particular, using a single-species growth model increases uncertainty in predicting stand growth, given the high species diversity in temperate forests in East Asia. Therefore, in this study, we identified the growth curve of 17 species-specific distributed in Korean temperate forest as well as the growth trend over the last 30 years (1976–2005). For this purpose, the species distribution and growth characteristics of 17 major Korean species of trees were analyzed using 13,808 tree-ring series from the 5th National Forest Inventory, which was conducted between 2006 and 2010. The growth characteristics of each species were analyzed using the average growth curve specific to each species, and the yearly growth trend was examined through residual analysis of the average growth curve. The distribution range of the 17 major tree species varied by species, as did the growth rate, ranging from 7 cm² · year⁻¹ to 17 cm² · year⁻¹ for the 30-year-old average basal area increment (BAI). Over time, fast-growing tree species exhibited initially high BAI, followed by a sharp decline from the 2000s. In contrast, broadleaf trees showed a continuous increase. Furthermore, a comparison of the total volume of individual trees and the volume of the yield table revealed that accurately estimating the actual forest volume was challenging. This study contributes to improving the accuracy of productivity predictions for temperate forests, underscoring the necessity to investigate the interaction between climate and forest succession in the future. • Species-specific growth models were developed using Inventory data of Korea. • The growth trends of species were influenced by their successional stage. • The tree growth was observed to be greater than that predicted. [ABSTRACT FROM AUTHOR]

Desertification is a worldwide problem caused by climate change and human activity in dryland regions. In China, approximately 27% of the land surface is desertified. In these desertified ecosystems, aboveground interactions are known to greatly affect ecological succession, but belowground soil microbial communities are relatively unstudied. It is not yet clear how these communities change with different vegetation patch types (e.g., shrub vs. grass) across successional stages in dryland ecosystems. In this study, we assessed the effects of shrub patches (dominated by Artemisia ordosica) and grass patches on soil microbial community diversity, soil environment, and soil substrates across three successional stages (mobile, semi‐mobile, and fixed dunes) in a sand dune ecosystem in the Kubuqi Desert, China. Microbial alpha diversity, as indicated by the Shannon index or operational taxonomic unit (OTU) richness, was not affected by patch type but increased with successional stages. Patch type‐ or successional stage‐induced changes in soil bacterial and fungal alpha diversity were mainly associated with soil organic carbon. Unlike alpha diversity, soil microbial beta diversity was greatly affected by successional stage and patch type. The Mantel test revealed that changes in soil bacterial beta diversity were mainly associated with soil organic carbon, and changes in soil fungal beta diversity were mainly associated with soil organic carbon and soil pH. Microbial OTU richness responded more strongly to the successional stage than the microbial Shannon index, indicating that microbial OTU richness can be used as an indicator of successional status in desert ecosystems. The consistent differences in microbial beta diversity between shrub and grass patches across the three successional stages indicate that shrubs significantly influence soil microbial communities in desert ecosystems. [ABSTRACT FROM AUTHOR]

Plants growing in subtropical regions are often affected by high temperature and high light in summer and low temperature and high light in winter. However, few studies have compared the photoprotection mechanism of tree species at different successional stages in these two environments, although such studies would be helpful in understanding the succession of forest communities in subtropical forests. In order to explore the strategies used by dominant species at different successional stages to cope with these two environmental conditions, we selected two dominant species in the mid-successional stage, Schima superba and Castanopsis chinensis, and two dominant species in the late-successional stage, Machilus chinensis and Cryptocarya chinensis. The cell membrane permeability, chlorophyll fluorescence, chlorophyll content, and a few light-protective substances of these dominant species were measured in summer and winter. The results show that in summer, the young leaves of dominant species in the mid-successional stage showed higher anthocyanin content and superoxide dismutase (SOD) activity, while those in the late-successional stage showed higher flavonoid and total phenolic content, total antioxidant activity, non-photochemical quenching (NPQ), and carotenoid/chlorophyll (Car/Chl) ratio. In winter, young leaves of dominant species in the mid-successional stage were superior to those in the late-successional stage only in terms of catalase (CAT) activity and NPQ, while the anthocyanin, flavonoids, and total phenol content, total antioxidant capacity, and Car/Chl ratio were significantly lower compared to the late-successional stage. Our results show that the dominant species in different successional stages adapted to environmental changes in different seasons through the alterations in their photoprotection strategies. In summer, the dominant species in the mid-successional stage mainly achieved photoprotection through light shielding and reactive-oxygen-species scavenging by SOD, while the antioxidant capacity of trees in the late-successional stage mainly came from an increased antioxidative compounds and heat dissipation. In winter, the dominant species in the mid-successional stage maintained their photoprotective ability mainly through the scavenging of reactive oxygen species by CAT and the heat dissipation provided by NPQ, while those in the late-successional stage were mainly protected by a combination of processes, including light shielding, heat dissipation, and antioxidant effects provided by enzymatic and non-enzymatic antioxidant systems. In conclusion, our study partially explains the mechanism of community succession in subtropical forests. [ABSTRACT FROM AUTHOR]

Soil biota are abundant in grasslands; however, disturbances such as invasions or conversion to agriculture may alter soil communities in ways that reduce the success of native species and/or increase the competitiveness of invasive plants. Predicting the magnitude and direction of these effects on plant growth remains challenging, particularly in high nutrient soils, which can impact plant‐microbe and plant–plant interactions in different ways. In greenhouse experiments, invasive and native Palouse prairie plants were grown individually and in a community with soil from a Palouse prairie remnant, soil invaded by Bromus tectorum, a nutrient release treatment, or no treatment. We tested (1) whether arbuscular mycorrhizal fungal infectivity and function of soil biota differ in invaded versus remnant prairie soil; (2) if growth responses to soil biota are related to plant nutrient demands; (3) if individual plant responses to soil biota predict competitive outcomes; and (4) if successional status predicts plant growth response to soil biota in high nutrient soils. We found no difference in mycorrhizal inoculation potential or function in invaded versus remnant prairie soil. We show a continuum of plant growth responses to soil biota, which correlate with nutrient responses, even under the high baseline soil nutrient conditions. We found that growth response to soil biota may increase with native plant successional stage. Understanding how different plant species respond to soil biota and assessing functionality of soil biota at a site will help managers plan restorations in high nutrient soils, and inform whether inoculations may be beneficial at a particular site. [ABSTRACT FROM AUTHOR]

Soil phosphorus (P) availability often limits plant productivity. Classical theories suggest that total P content declines at the temporal scale of pedogenesis, and ecosystems develop toward the efficient use of scarce P during succession. However, the trajectory of ecosystem P within shorter time scales of succession remains unclear. We analyzed changes to P pools at the early (I), middle (II), and late (III) stages of growth of plantation forests (PFs) and the successional stages of natural forests (NFs) at 1969 sites in China. We found significantly lower P contents at later growth stages compared to earlier ones in the PF (p <.05), but higher contents at late successional stages than in earlier stages in the NF (p <.05). Our results indicate that increasing P demand of natural vegetation during succession, may raise, retain, and accumulate P from deeper soil layers. In contrast, ecosystem P in PF was depleted by the more rapidly increasing demand outpacing the development of a P‐efficient system. We advocate for more studies to illuminate the mechanisms for determining the divergent changes, which would improve forest management and avoid the vast degradation of PF ecosystems suffering from the ongoing depletion of P. [ABSTRACT FROM AUTHOR]

Abstract Background Metabolic scaling theory (MST) is still in debate because observed allometric exponents often deviate from MST predictions, and can change significantly depending on environment, phylogeny, and disturbance. We assembled published scaling exponents from literatures for three allometric relationships linked to biomass allocation: leaf biomass-diameter (L-D), stem biomass-diameter (S-D), and root biomass-diameter (R-D). We used data from natural forests and plantations across China to test the following hypotheses: 1) the allometric relationships of trees support the predictions of MST on a broad scale; 2) the observed deviations from MST predictions are caused by climate, biotic factors, and/or phylogeny; 3) abiotic and biotic factors influence allometric relationships in plantations and natural forests differently, and different allometric relationships (i.e. L-D, S-D, and R-D) are affected differently. We related these scaling exponents to geographic climate gradient, successional stage, stand density, leaf form and phenology, and phylogeny. We used mixed-effect models to examine the major factors affecting tree allometries. Results In natural forests, S-D and R-D scaling exponents were consistent with MST predictions in primary forests, but were significantly lower in secondary forests. Both S-D and R-D scaling exponents in plantations had a medium value that fell between those of the secondary and primary forests, despite plantations being similar in species characteristics and age to secondary forests. The S-D and R-D exponents were significantly affected by factors that are not yet considered in MST, including winter coldness which explained 2.76% – 3.24% of variations, successional stage (7.91% – 8.20% of variations), density (a surrogate for competition, 5.86% – 8.54% of variations), and especially phylogeny (45.86% – 56.64% of variations explained). However, the L-D scaling exponents conformed to MST predictions in primary, secondary, and plantation forests, and was not strongly explained by most factors. Conclusion MST is only applicable to primary (steady-state) forests, and climate, biotic factors and phylogeny are causes of the observed deviations of allometric relationships from MST predictions. Forest management practices in plantations have a strong influence on tree allometries. L-D allometry is more strongly controlled by biophysical constraints than S-D and R-D allometries, however, the mechanisms behind this difference still need further examinations.

Species diversity can contribute to the resilience of the ecosystem and can be assessed through the soil seed bank (SSB). SSB is an indicator of forest development after the occurrence of disturbances. Thus, this study aimed at evaluating the relation of the soil fertility with the soil seed bank and the variation of seed bank species diversity at distinct successional stages after abandonment of pasture (25, 35, 45 and > 50 years). Ten samples of soil were collected per site, being distributed in trays and arranged in a greenhouse for a germination analysis. Results indicate that species diversity in SSB is higher in young forests than in mature forests. In addition, soil characteristics are different among successional stages, in which the young forests are associated with higher availability of nutrients. Finally, forests in early stages have higher potential for recovery of degraded areas in relation to the forest seed bank in advanced stages. [ABSTRACT FROM AUTHOR]

The associations between morphological fruit types, fruit and seed colors, and functional plant traits: life forms, epiphytism, physiology, nutritional relationships, fruit phenology, and successional stage, were determined for 1,139 plant species from contrasting plant communities. Texture and dehiscence were closely related. Dehiscence is largely associated with dry tissues; indehiscence, however, is an attribute of both dry and fleshy fruits. The number of morphological fruit types was 28 or 55 for Gray’s and Spjut’s classifications, respectively. Fruits were predominantly dark in color (brown, purple-black, black or green), whilst seeds had both dark and light colors (brown, beige, or black). The most representative associations were mainly found between the more abundant fruit types and the colors most common. Asymmetries in the level of specialization, whereby less common fruit and seed colors tended to be associated with the most common fruit types, were also found. Fleshy fruits showed more variation as regards their coloration, and only drupes and berries showed a tendency towards a specific color: purple-black. The relationships among fruit type and color, seed color, and functional plant traits revealed the following trends: trees produced both fleshy and dry fruits; shrubs produced fleshy fruits; and herbaceous species, dry fruits. Woody species tended to have dark or bright colors, depending on their seed dispersal mechanisms and phylogenetic relations. Epiphytes were associated with dry-dehiscent fruits and brown seeds, and parasitic-hemiparasitic species had predominantly fleshy-indehiscent fruits. Pioneer species were more likely to have dry fruits, whereas fleshy fruits tended to be more frequent in late successional stage species. The C4 species, mostly herbs, had mainly one-seeded dry fruits, but multi-seeded fruits in succulent-CAM species showed morphologically diverse fruit types. Unripe and ripe fruits showed seasonal changes, especially during the rainy-dry transition period for the most abundant morphological fruit types, dry fruits during the dry period and fleshy fruited species was positively associated with the rainy season. All these trends are discussed with regard to their environmental significance and the relationships between fruit morphology, colors and functional groups. [ABSTRACT FROM AUTHOR]

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Recovery of coral reefs after physical damage sustained from storm events can be affected by various factors. Here, we examined the initial recovery of a coral reef at the southern end of uninhabited Lalo Atoll of Papahānaumokuākea Marine National Monument after its complete destruction by Hurricane Walaka in 2018. While the site was still mostly (98%) covered by a mixture of rubble and sand, surveys utilizing underwater photogrammetry allowed for detailed quantitative assessments of benthic cover and confirmed colonization of coral (Pocillopora meandrina and Porites lobata), macroalgae and sponges. The proportion of sand in the rubble–sand mixture also decreased from the level observed in 2019. Visual fish surveys confirmed the presence of 35 reef fish species, a large increase from no reef fish in 2019, despite the low biotic benthic cover. Overall, the colonization of benthic organisms and the return of reef fish, which is potentially supported by the benthos and cryptofauna in the rubble bed, offer positive signs of reef recovery. The photogrammetric surveys in the present study captured the subtle changes in the benthic cover and provided us with a procedure to continue monitoring the succession of the site. Continuous monitoring of the site should reveal whether the reef returns to the original state of Acropora coral dominance or progresses towards a coral assemblage with a different composition.

Understanding the variation of functional traits of plant species along forest successional gradients may provides useful insights into community assemblages. However, species performance during forest succession is controversial. We explored the variation of leaf traits along a forest succession by examining ten leaf traits in four successional stages in a monsoon evergreen broad-leaved forest in Southwest China. Results showed significant differences in all leaf traits except leaf area and leaf carbon content among the successional stages. Five leaf traits were highly correlated to successional stage, while the first principal component showed no correlation with successional stage. The first principal component accounted for 56.1% of the total variation in all ten leaf traits. Almost 50% of the relationships between leaf traits differed along the examined successional gradient, indicating that leaf traits were affected by the successional stage.

Copyright of Ciência Florestal (01039954) is the property of Ciencia Florestal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plants develop diverse adaptive traits in changeable environments, yet whether plant defense traits change during succession remains unclear. In this study, we investigated the young leaf physical traits (i.e., upright orientation of leaves, trichomes, an enhanced cuticle, and a multilayered epidermis) and leaf color trait (i.e., red pigmentation) of dominant plants in three subtropical forests. These forests included a pioneer forest, a mixed coniferous-broadleaved forest, and a monsoon-evergreen broadleaved forest representing early, middle, and later successional stages, respectively. Our results show that the red color trait in young leaves is related to anti-herbivory defense, and the percentage of species with red young leaves is higher in later than in early succession. Physical defense tends to be weaker for red young leaves than for green young leaves in early and middle successions. In addition, the number of defense traits of young leaves increases with succession. We speculate that young leaves in subtropical forests depend increasingly on multiple defense traits during succession because of the increased biotic stresses and environmental complexity in later succession. [ABSTRACT FROM AUTHOR]

Highlights • Most large trees should be sampled to estimate stand productivity accurately. • The sampling ratio of small trees had limited effect on the estimation accuracy. • A model was developed to provide optimum sampling designs based on the forest structure and climate factors. • Optimum sampling designs predicted by the model could well estimate stand productivity history. • Traditionally used tree-ring sampling methods may produce great uncertainties on the estimation of productivity. Abstract Field-measured forest productivity and its time-series are critical for understanding the impact of climate change on forest carbon cycling, and also for validating process-based models. Tree-rings are widely used to reconstruct stand productivity history. However, it remains ambiguous how to ensure a good sample design to estimate forest productivity precisely, and meanwhile minimize the sampling effort. Here we addressed the following questions: (1) how many minimum tree-ring samples are needed to estimate forest productivity history accurately? (2) Can we predict optimum sampling design from climate conditions and forest structure? (3) Are commonly used sampling methods accurate enough? We set up 48 forest plots across four succession stages at four study sites along a latitude gradient in Northeast China. Tree-rings were sampled from all trees in each plot, and stand and individual productivity history over the past 20 years was reconstructed. We simulated different sampling designs by randomly extracting trees in each plot to select an optimal design that could estimate stand productivity history accurately but with the least sampling size, and to evaluate the accuracy of commonly used tree-ring sampling methods. We analyzed the influence of climatic gradient, forest type, distribution of productivity and biomass across DBH classes, and further developed models to predict sampling design. It was found that ca. 100%, 42%, 18% and 10% of individuals should be sampled from the 1/4 largest to the 1/4 smallest trees, respectively, to ensure an accurate estimation of stand productivity history. The optimum sampling design was highly related with the distribution of productivity and biomass across diameter classes of the plots, and changed significantly along climate gradient but showed no clear trend across successional stages. Sampling designs inferred from models based on climate indices and the biomass ratio in each diameter class by each plot could estimate stand productivity history satisfactorily from other validation plots. It was also showed that previous sampling methods to estimate forest productivity may incur large uncertainties. As such, these data should be viewed with caution. We proposed a new tree-ring sampling strategy based on the fact that forest productivity and its temporal variation were largely determined by large trees. We further showed that the optimal sampling design was predictable from forest structure and climate conditions. More studies are needed in other regions to develop models to optimize sampling designs for different forest types under different climate conditions, for a more accurate estimation of forest productivity dynamics under global climate change. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Questions: Water source segregation among plant species has been widely observed in a variety of ecosystems. However, whether correlated segregation occurs at a community level and its relationship to successional stages has rarely been studied. Location: Open shrubland, dense shrubland and secondary forest on adjacent rocky karst hill slopes, southwest China. Methods: Plant samples of the five most dominant species from each community type were collected seven times throughout the growing season. Dynamics of stem water isotope values (SWIVs) for the five species within each community were examined using a regression analysis of the averaged isotope value of each species v sampling time. Overall variation of SWIVs was compared among communities. Similarities between communities were further distinguished by comparing the dynamics of SWIVs for the species shared by different communities and studying their relationship to rainwater. Results: The fitted regression line for each community was statistically significant (p < 0.05), with all species falling between the upper and lower limit lines of the 95% prediction interval of stem water isotopic composition; these convergent dynamics point toward a similar water source for different species within each community. The common species from the secondary forest exhibited fewer fluctuations in SWIVs than those from the open shrubland, which was consistent with the significantly smaller overall variation in SWIVs for the secondary forest. As smoother dynamic of SWIVs over time is related to using rainwater received over a longer period of time, the secondary forest was estimated to be less dependent on rainwater received within short time spans than the other two communities. Conclusions: Our study revealed community‐level water source segregation in a karst region. Early successional plant communities were more dependent on recent rainwater received within short time spans and thus were potentially more vulnerable to reduced rainfall frequency than late successional stage communities. Dominant species from the same community on karst rocky hill slope relied on a similar main water source and exhibited convergent dynamics of stem water isotope values over time. Moreover, early successional plant communities were more dependent on recent rainwater received within short time spans than late successional ones. [ABSTRACT FROM AUTHOR]

Abstract Knowledge on the role of seagrass leaf elements and in particular micronutrients and their ranges is limited. We present a global database, consisting of 1126 unique leaf values for ten elements, obtained from literature and unpublished data, spanning 25 different seagrass species from 28 countries. The overall order of average element values in seagrass leaves was Na > K > Ca > Mg > S > Fe > Al > Si > Mn > Zn. Although we observed differences in leaf element content between seagrass families, high intraspecific variation indicated that leaf element content was more strongly determined by environmental factors than by evolutionary history. Early successional species had high leaf Al and Fe content. In addition, seagrass leaf element content also showed correlations with macronutrients (N and P), indicating that productivity also depends on other elements. Expected genomes of additional seagrass species in combination with experiments manipulating (micro)nutrients and environmental drivers might enable us to unravel the importance of various elements to sustain productive and flourishing meadows. Highlights • Global overview of seagrass leaf content for Al, Ca, Fe, K, Mg, Mn, Na, S, Si, & Zn • Large variation in leaf elements between and within families and species • Physiology and environmental conditions drive seagrass leaf element content. • Successional stage explained leaf content more than evolutionary history. • Further analyses of element impact on productivity and adaptation required. [ABSTRACT FROM AUTHOR]

Abstract: Plant establishment is a challenge in semiarid environments due to intense and frequent drought periods. The presence of neighboring trees (nurses) can increase the establishment of seedlings (targets) by improving resource availability and microclimate. The nurse effect, however, might vary depending on nurse‐target species combinations but factors that predict this specificity are poorly known. We used a multispecies experiment to investigate the facilitation potential of trees from a range of successional stages, focusing on how nurse functional traits can predict species‐specific interaction outcomes. We conducted a factorial field experiment in a Brazilian semiarid tropical forest during a severe drought period. Sixty pairs of interacting tree species, 20 potential nurses, and three targets were used. Seedlings of all targets were planted both under and far from the nurse canopy, in a randomized block design replicated five times. Target growth and survival were monitored for 275 days from the beginning of the dry season, and interaction outcomes were calculated using the Relative Interaction Intensity (RII) index. Nurse functional traits such as successional stage, height, wood density, and canopy diameter were used as explanatory variables to predict RII values. The average effect of nurse species on target plants was in general positive, that is, seedling survival and growth increased under the nurse canopy. However, for growth pairwise interactions were significantly species specific. Successional stage was the only functional trait explaining RII values, with pioneer tree species being stronger facilitators than later successional trees. However, the explanation power of this variable was low, and positive, negative, or neutral interactions were found among nurse trees of all successional stages. Because seedling mortality during drought in semiarid systems is high, future studies should investigate how nurse traits related to water use could influence nurse facilitation skills. [ABSTRACT FROM AUTHOR]

As Cuestas Basálticas apresentam-se na paisagem da região central do Estado de São Paulo e caracterizam-se pela Floresta Estacional Semidecidual. O objetivo deste trabalho foi caracterizar a estrutura, estádio sucessional e a diversidade da mata ripária integrante da sub-bacia do córrego do Cintra, situada na região da Cuesta de Botucatu. O método fitossociológico utilizado em três áreas foi o de ponto-quadrante com dois indivíduos amostrados em cada quadrante e de tamanho > 5 m e < 5 m de altura. Foi utilizado o teste de Friedman na comparação das espécies arbóreas nas três áreas, seguido do teste de Dunn, ao nível de 5% de significância. Os índices analisados foram dominância relativa − DoR, densidade relativa − DR, e índice de valor de cobertura − IVC, obtidos através de cálculo em planilha eletrônica; o estádio sucessional foi determinado pela proporção relativa entre os números de indivíduos de espécies de diferentes sinúsias identificadas; a diversidade de espécies foi estudada com base nos índices de diversidade de Shannon-Wiener (H’), Pielou (J) e Simpson, conotação 1-D, através do programa Past. Nas três áreas de amostragem foram encontradas 2.241 indivíduos arbóreos de 145 espécies, pertencentes a 55 famílias botânicas, sendo as mais representativas Fabaceae com 16,3%; Lauraceae, Myrtaceae e Boraginaceae com 7% cada, totalizando 37,3% da amostragem total. As espécies com maior DoR, DR e IVC nas áreas 1, 2 e 3 respectivamente foram Calophyllum brasiliense, Piptadenia gonoacantha e Gochnatia polymorpha. O estádio sucessional na área 1 foi considerado mais tardio, na área 2 intermediário, e pioneiro na área 3, além da diversidade (H’A1 = 4,08; H’A2 = 3,79; H’A3 = 3,31 nats/ind-1) das espécies, que foi considerada alta e boa equabilidade nas três áreas. Portanto, na área 3 os índices indicaram maior dominância de poucas espécies que está em processo de sucessão, com a necessidade de revegetação e regeneração florestal. Basaltic Cuestas are located in the middle-west landscapes of São Paulo state and are characterized by Semideciduous Forest. The aim of this study was to characterize the structure, the successional stage and the diversity of the riparian forest of the Cintra stream sub-watershed, located at the region of Botucatu Cuesta. The phytosociological method applied to the three areas was the point-quarter, respectively > 5 m and < 5 m of height. The Friedman test was adopted in the comparison among tree species in all three areas and was followed by Dunn’s test, at 5% significance. The analyzed indexes were relative dominance − (DoR), relative density − (DR), and covering index − (IVC), obtained by means of an electronic spreadsheet; the successional stage was determined by the relative proportion among the numbers of individuals of different synusiae species identified; and the diversity of species was studied based on the diversity indexes of Shannon-Wiener (H’), Pielou (J) and Simpson, connotation 1-D, using the software Past. In the three sampling areas, 2,241 arboreal individuals of 145 species were found, which belong to 55 botanical families, and the most representative families were Fabaceae, 16.3%; Lauraceae, Myrtaceae and Boraginaceae, 7% each, totaling 37.3% of the total sampling. The species with the highest DoR, DR and IVC in areas 1, 2 and 3, respectively, were Calophyllum brasiliense, Piptadenia gonoacantha and Gochnatia polymorpha. The successional stage in area 1 was considered late, in area 2 was intermediate, and the one in area 3 was pioneer, while the diversity (H’A1 = 4.08; H’A2 = 3.79; H’A3 = 3.31 nats/ind-1) of species was considered high and with good equitability for all 3 areas. Therefore, the indexes indicated greater dominance of a few species in area 3, which is in succession process, requiring reforestation and forest regeneration.

This study investigated seasonal patterns in stoichiometric ratios, nutrient resorption characteristics, and nutrient use strategies of dominant tree species at three successional stages in subtropical China, which have not been fully understood. Fresh leaf and leaf litterfall samples were collected in growing and nongrowing seasons for determining the concentrations of carbon (C), nitrogen (N), and phosphorus (P). Then, stoichiometric ratios (i.e., C:N, C:P, N:P, and C:N:P) and resorption parameters were calculated. Our results found that there was no consistent variation in leaf C:N and C:P ratios among different species. However, leaf N:P ratios in late-successional species became significantly higher, indicating that P limitation increases during successional development. Due to the P limitation in this study area, P resorption efficiency and proficiency were higher than corresponding N resorption parameters. Dominant tree species at early-successional stage adopted 'conservative consumption' nutrient use strategy, whereas the species at late-successional stage inclined to adopt 'resource spending' strategy. [ABSTRACT FROM AUTHOR]

Background: Baekdudaegan was designated in 2005 as a protected area to prevent destruction and conserve. However, there are many disturbed and destroyed areas. The total disturbed area amounts to 25.9 km² (0.94%), including 13.4 km² (0.49%) in the core area and 12.5 km² (0.45%) in the buffer area. This study aims to classify the vegetation types established in the disturbed areas and diagnose the current conditions for ecological restoration in the forest ecosystem. Methods: We surveyed the vegetation in the disturbed areas of Daegwallyeong and Chupungryeong and the surrounding natural areas. The survey conducted from July to September 2015 targeted a total of 54 quadrats by Braun-Blanquet method (Daegwallyeong, 22; Chupungryeong, 32). We also investigated the height and coverage of each layer. We classified the vegetation types based on the field data and analyzed the ratio of life form and the exotic plants, species richness, and vegetation index (Hcl). The Normalized Difference Vegetation Index (NDVI) was calculated from rapideye satellite imagery in 2014 and 2015. Results: Vegetation types were classified into 11 groups according to the criteria that included successional sere or plantation at first, followed by developmental stage and origins. As a result of the analysis of the survey data, species richness, vegetation index (Hcl), ratio of tree plants, and the NDVI tended to increase, while the ratio of the exotic plants tended to decrease with the time since disturbance. These indicators had the classified values according to the vegetation types with time since the disturbance. Conclusions: These indicators can be effectively used to diagnose the conditions of the present vegetation in the disturbed area of the Baekdudaegan area. In addition, the NDVI might be effective for the diagnosis of the disturbed status instead of the human efforts based on the higher spatial resolution of satellite imagery. Appropriate diagnosis of the disturbed forests in the Baekdudaegan area considering the established vegetation types is essential for the elaboration of restoration plans. In addition, restoration target and level should be different according to the disturbed status of restoration site. [ABSTRACT FROM AUTHOR]

Preliminary analysis of the seed bank can help in the planning and execution of the transposition strategie and, thus, potentiate the success of ecological restoration. We objective to evaluate the floristic composition of the seed bank in three fragments of the seasonal forest in the center of Rio Grande do Sul. The treatments were center of forest fragment with rectangular design in initial to intermediate succession stage (FI), center (FII-C) and border positions (FII-B) of fragment with circular design in initial to intermediate succession stage and stabilized gully in initial succession with elongated design (FIII). Samples were collected to 5 cm depth with frame of 0.25 x 0.25 m, eight repeats by treatments. Emerging seedlings were counted and identified. The sites were compared for the number of germinated seeds, species richness, lifeforms and origins by the Kruskal-Wallis test. A total of 473 individuals belonging to 30 species and 13 botany families were observed. The greatest richness was found in FII-B (17 spp). FIII had the highest number of germinated seeds (576 ind./m²), higher germination of Poaceae and higher density of invasive exotics. FI and FII-B showed greater diversity and low number of invasive exotic species. We conclude which the preliminary analysis was efficient to identify areas favorable to donation for soil transposition, the seasonal forest remnants in the intermediate successional stage (FI and FII-B) may be indicated as donors of the seed bank, because they present greater diversity and low number of invasive alien species. [ABSTRACT FROM AUTHOR]

Selective logging with natural regeneration is advocated as a near-to-nature strategy and has been implemented in many forested systems during the last decades. However, the efficiency of such practices for the maintenance of forest species are poorly understood. We compared the species richness, abundance and composition of ground-dwelling beetles between selectively logged and unlogged forests to evaluate the possible effects of selective logging in a subtropical broad-leafed forest in southeastern China. Using pitfall traps, beetles were sampled in two naturally regenerating stands after clearcuts (ca. 50 years old, stem-exclusion stage: selectively logged 20 years ago) and two mature stands (> 80 years old, understory re-initiation stage: selectively logged 50 years ago) during 2009 and 2010. Overall, selective logging had no significant effects on total beetle richness and abundance, but saproxylic species group and some abundant forest species significantly decreased in abundance in selectively logged plots compared with unlogged plots in mature stands. Beetle assemblages showed significant differences between selectively logged and unlogged plots in mature stands. Some environmental characteristics associated with selective logging (e.g., logging strategy, stand age, and cover of shrub and moss layers) were the most important variables explaining beetle assemblage structure. Our results conclude that selective logging has no significant impacts on overall richness and abundance of ground-dwelling beetles. However, the negative effects of selective logging on saproxylic species group and some unlogged forest specialists highlight the need for large intact forested areas for sustaining the existence of forest specialist beetles. [ABSTRACT FROM AUTHOR]

Understanding the variation of functional traits of plant species along forest successional gradients may provides useful insights into community assemblages. However, species performance during forest succession is controversial. We explored the variation of leaf traits along a forest succession by examining ten leaf traits in four successional stages in a monsoon evergreen broad-leaved forest in Southwest China. Results showed significant differences in all leaf traits except leaf area and leaf carbon content among the successional stages. Five leaf traits were highly correlated to successional stage, while the first principal component showed no correlation with successional stage. The first principal component accounted for 56.1% of the total variation in all ten leaf traits. Almost 50% of the relationships between leaf traits differed along the examined successional gradient, indicating that leaf traits were affected by the successional stage. [ABSTRACT FROM AUTHOR]

A utilização da diversidade de plântulas de espécies arbóreas, oriundas de áreas cuja vegetação teve a supressão autorizada, no enriquecimento de viveiros, tem sido recomendada como uma técnica alternativa na produção de mudas. Neste trabalho, avaliamos a sobrevivência de plântulas transplantadas da regeneração natural de uma floresta madura para um viveiro de mudas em uma área de transição Amazônia-Cerrado, Mato Grosso, Brasil. Foram alocados três transectos de 10 x 1 m, com 10, 50 e 500 m de distância da borda de onde foram coletados todos os indivíduos lenhosos entre 5-20 cm de altura, no período da manhã (7h às 9h), e sequencialmente plantados em sacos plásticos. Os indivíduos foram identificados, quantificados e classificados quanto ao estágio sucessional. A sobrevivência das plântulas foi avaliada durante quatro meses. No total foram coletados 1.179 indivíduos arbóreos pertencentes a 48 espécies, 31 gêneros e 23 famílias, dos quais 71% sobreviveram. No conjunto dos dados, houve um aumento gradativo na abundância e riqueza de espécies arbóreas da borda para o interior da floresta, sendo maior a 500 m. A abundância e o número de espécies não pioneiras coletadas foram maiores que as pioneiras. Os resultados apontam elevadas taxas de sobrevivência e que a técnica de transplante pode facilitar o enriquecimento de viveiros com espécies regionais de difícil obtenção e de diferentes grupos funcionais. The use of the diversity of tree species, present in areas where vegetation removal had been authorized, as means of nursery enrichment, has been recommended as an alternative technique for seedling production. The aim of this study was to evaluate the survival rate of transplanted seedlings, from natural regeneration in mature forests, to the nursery. Seedlings were obtained from three 10 x 1 m transects allocated in Amazon transitional forest in Mato Grosso state, Brazil. All woody individuals with heights between 5 and 20 cm were collected at 10, 50, and 500 m from the forest edge, during the morning period (7 a.m. to 9 a.m.), and subsequently replanted into plastic bags. Identification of species and successional stage classification followed the replanting. Survival was evaluated monthly, for four months. In total, 1,179 tree seedlings were collected and they represented 48 species, 31 genera, and 23 families, with an overall survival of 71%. Richness and abundance of tree seedlings increased from the edge, with highest values at 500 m. Abundance and richness of non-pioneer seedlings were higher than those of pioneer species. These results suggested high survival rates and that transplanting native seedlings could be used to enrich species diversity in nurseries, through the inclusion of species that are difficult to obtain (by seeds) and species belonging to different functional groups.

O presente trabalho compara a composição e estrutura de assembléias vegetais de fragmentos florestais, com diferentes características em relação ao tipo de propriedades rurais do entorno, tamanho e histórico de uso, com uma área localizada dentro de uma unidade de conservação (área controle), na bacia do rio Guapiaçu. Em cada fragmento foram delimitadas duas parcelas de 50 x 100m, na mesma orientação sudoeste, no interior das quais foram medidos os DAP (Diâmetro Acima do Peito) e altura de todos indivíduos com DAP ≥ 5 cm e identificados até o menor nível taxonômico possível. A densidade, área basal total, riqueza e diversidade foram calculados. As assembléias foram comparadas quanto aos seus valores diâmétricos e proporção de indivíduos em classes de diâmetro. Os parâmetros fitossociológicos foram calculados e as vinte espécies de maior cobertura foram selecionadas com vistas à comparação da composição específica e de suas caracteríticas sucessionais. Todas as assembleías estudadas apresentam alta riqueza e diversidade de espécies, sendo igualmente constatadas, em relação à área controle, diferenças significativas em pelo menos uma das caracteríticas analisadas. Todas apresentam uma menor proporção de indivíduos nas classes diâmetricas maiores e de espécies secundárias tardias que na área controle. No entanto, para algumas delas correspondem valores totais de diâmetro igual ou maiores que os da área controle por conta da maior proporção de indivíduos em classes diâmetricas intermediárias que parece contribuir mais para o aumento desses valores. De forma geral, há maior abundância de espécies pioneiras e secundárias iniciais nos fragmentos florestais, porém a proporção destas categorias sucessionais varia entre eles evidenciando diferenças dos estágios sucessionais em que se encontram. Estas diferenças poderiam estar relacionadas a certa variabilidade dos distúrbios identificados no entorno. Os resultados obtidos aqui sugerem que fragmentos de mata rodeados por pequenas propriedades encontram-se em estágios sucessionais mais inicias e sujeitos a distúrbios mais severos.This paper presents an analysis of the composition and structure of plant assemblages of forest fragments with different characteristics (in relation to the type of rural properties in the surrounding area, size and disturbance history) and an area located within a Conservation Unit (control area) in the Guapiaçu river basin. In each fragment, two plots of 50 x 100m were delimited to the South and West, the height and DBH of all trees with DBH ≥ 5 cm were measured, and the individuals were identified to the lowest possible taxonomic level. The density, basal area and diversity were calculated and the DAP values and proportion of individuals in the diameter classes were compared between the assemblages. The phytosociological parameters were also calculated and twenty species of higher coverage indices were selected to compare the species composition and their successional characteristics. All assemblages studied had high species richness and species diversity. However, when compared to the control, all of them had significant differences in at least one of analyzed characteristics. All had a lower proportion of individuals in the largest diameter class and late secondary species. However, these differences did not corresponded to differences in the comparisons of individual DAP values. Some assemblages had DAP values equal to or higher than the control area. In fact, within some fragments, the higher proportion of individuals in the intermediate diameter classes contributes more to the total basal area value. In general, there was a greater abundance of pioneer and early secondary species in the forest fragments, but the proportion of these successional groups varied between them, showing the subtle differences in the successional stages that these fragments are in. These differences could be related to some variability of the environmental disturbances identified. Based on the results, it was found that the forest fragments surrounded by small farms are in initial successional stages and have been subjected to severer disturbances.

Nutrient-poor, semi-natural grasslands are among the most species-rich ecosystems across Europe. However, due to the transition from pre-industrial farming to modern agriculture, the extent of such grasslands has greatly decreased and the remaining patches have often suffered from habitat deterioration. Here, we analysed the effects of land-use and climate change as well as of nitrogen deposition on plant communities of dry (sand) (n = 118) and wet grasslands (n = 30) in a protected area, representative for the NE German young moraine landscape. Our study revealed that over a time period of 25 years, plant species composition in protected grasslands has changed considerably. Overall, plant species richness increased in both dry and wet grasslands from 1994 to 2019. The number of threatened species, however, decreased in dry but increased in wet grasslands. Land-use history was identified as the major driver of changes in species composition within the studied semi-natural grasslands. In wet grasslands, after >30 years of abandonment prior to the first survey, species-rich communities such as the Molinietalia have successfully been restored through the re-introduction of continuous, low-intensity management (mostly mowing once in late summer) shortly before the first survey. This has led to an increase of often threatened, light-demanding species of nutrient-poor wet grasslands. In dry grasslands, however, changes in vegetation were often contrary to those in wet grasslands; for example dry grasslands exhibited an increase in the nitrogen indicator value while it decreased in wet grasslands. Overall, open, nutrient-poor dry grasslands rich in stress-tolerant and often threatened species have been replaced by dense, more mesophytic grasslands with competitive generalists and some ruderal annuals. These successional changes were caused in particular by (i) an increase in abandonment on the least productive soils, (ii) undergrazing in permanent pastures and (iii) an insufficient time period since the re-introduction of grazing combined with a too low grazing pressure in new pastures on more productive soils. Nitrogen deposition was a further driver, especially on more acidic, dry soils. Additionally, grassland ruderalization was favoured by cropping of some plots and climate change since warm winters and severe summer droughts have led to an increase of annual ruderal species. [Display omitted] • Species composition in protected grasslands changed considerably from 1994 to 2019. • Threatened species decreased in dry but increased in wet grasslands. • Land-use history was the major driver of changes in species composition. • In wet grasslands: increase in species richness due to low-intensity management. • In dry grasslands: decrease in species richness due to abandonment and undergrazing. [ABSTRACT FROM AUTHOR]

[Display omitted] • Successional stage of trees systematically affects soil organic N transformations. • Turnover rate of soil N is slower under trees in late succession than that in early. • Microbial demand for C partially drives the assimilation of soil organic N. Organic nitrogen (N) is the most important N component of soil organic matter. However, knowledge on how tree species with different successional stages affect organic N transformations in soils remains limited. To address this issue, we sampled mineral soils (0–10 cm) under monocultures composed of tree species from different successional stages, including early (black alder and silver birch), early to mid (sycamore and European ash), and late (sweet chestnut, pedunculate oak and European beech), and measured the potential protease activity, the microbial uptake and respiration of 14C-labeled organic N (l -alanine and l -trialanine), and the mineralization of l -alanine N. The activities of alanine aminopeptidase and leucine aminopeptidase (153.8–341.9 and 91.6–147.9 nmol/g/h, respectively), the half-life of the uptake of alanine and trialanine (26.7–39.6 and 60.8–78.6 min, respectively), the half-life of the mineralization of alanine and trialanine (1.98–2.45 and 2.98–4.13 h, respectively) by soil microbes were altered by tree species from different successional stages, systematically changing the transformation chain of soil organic N. The turnover rates of soil organic N under trees of early to late successional stage appeared to decrease and the half-life appeared to increase significantly. The C:N ratio of soil microbial biomass was positively related to the half-life of 14C-labeled alanine and trialanine mineralization, and was negatively related to the carbon (C) use efficiency of alanine, suggesting that microbial demand for C could partially drive the assimilation of soil organic N. These results suggest that the successional stage of tree species play an important role in regulating the turnover rates of soil organic N. An improved understanding of how tree species from different successional stages influence microbial function and soil organic N cycling is beneficial to future afforestation and forest management, alleviating the impacts of global change on the ecosystem. [ABSTRACT FROM AUTHOR]

Climate change research has demonstrated that changing temperatures will have an effect on community-level dynamics by altering species survival rates, shifting species distributions, and ultimately, creating mismatches in community interactions. However, most of this work has focused on increasing temperature, and still little is known about how the variation in temperature extremes will affect community dynamics. We used the model aquatic community held within the leaves of the carnivorous plant, Sarracenia purpurea, to test how food web dynamics will be affected by high temperature variation. We tested the community response of the first (bacterial density), second (protist diversity and composition), and third trophic level (predator mortality), and measured community respiration. We collected early and late successional stage inquiline communities from S. purpurea from two North American and two European sites with similar average July temperature. We then created a common garden experiment in which replicates of these communities underwent either high or normal daily temperature variation, with the average temperature equal among treatments. We found an impact of temperature variation on the first two, but not on the third trophic level. For bacteria in the high-variation treatment, density experienced an initial boost in growth but then decreased quickly through time. For protists in the high-variation treatment, alpha-diversity decreased faster than in the normal-variation treatment, beta-diversity increased only in the European sites, and protist community composition tended to diverge more in the late successional stage. The mortality of the predatory mosquito larvae was unaffected by temperature variation. Community respiration was lower in the high-variation treatment, indicating a lower ecosystem functioning. Our results highlight clear impacts of temperature variation. A more mechanistic understanding of the effects that temperature, and especially temperature variation, will have on community dynamics is still greatly needed. [ABSTRACT FROM AUTHOR]

In the southern Julian Alps we described two communities whose tree layer is dominated by species from the genus Sorbus and noted two successional stages in the overgrowing of abandoned agricultural land (pastures, hay meadows). In the secondary succession on former subalpine pastures above the alp Planina Razor und under the Breginjski Stol ridge, where potential natural vegetation consists of subalpine beech forest, dwarf pine has been overgrown with mountain ash ( Sorbus aucuparia) whose stands are classified into the new association Rhododendro hirsuti-Sorbetum aucupariae. Whitebeam ( Sorbus aria) has established itself on steep former hay meadows in the belt of altimontane beech forests under Mts. Jalovnik and Krikov Vrh, on gullied slopes on mixed geological bedrock dominated by chert, and these stands are classified into the association Calamagrostio arundinaceae-Sorbetum ariae. While occupying only small areas these two pioneer stages, as the sites of some rare or protected species, are nevertheless important biotopes and play a vital role in protection against avalanches. [ABSTRACT FROM AUTHOR]

The biotic province of the Sierra Madre del Sur presents a mosaic of woodlands at different successional stages due to frequent modifications in land use. In this study, we analyzed changes in woody flora across three successional stages of pine-oak forest: early, intermediate, and mature. Vegetation composition and diversity were characterized in 10 plots (each 0.28 ha). The mature stage had the highest values for species richness, abundance, and diversity. Pioneer plants were dominant in the early-successional site and may promote the establishment of late-successional species. The vegetation structure was more complex in the mature stage, where members of the Quercus genus were co-dominant with Pinus species. Pine tree richness was highest in the early-successional stage, and its abundance increased at the intermediate-successional site. These results suggest that Pinus species can grow in perturbed and sunny environments but also require favorable edaphic and microclimatic conditions, such as those found in intermediate woodlands. Results of this fieldwork support the initial floristic composition succession model, which suggests that species present at early stages will also occur in subsequent stages. Ecological succession may be considered to be a natural restoration process, and thus, conservation strategies should focus on maintaining distinct successional communities in addition to mature forests in order to preserve a high number of species. [ABSTRACT FROM AUTHOR]