•Most species showed similar crown development trajectory, but some species showed interspecific variations in tree height-stem diameter relationships.•Parameters of tree architectural variable ...relationships differed in leaf phenology and seed dispersal types.•Large-statured species had more slender stems and had shallower and narrower crowns at small sizes, but similar crowns at large sizes.•Light-demanding species showed weak correlations between architectural variables and light requirement but exhibited wide crowns at the intermediate sizes.
Tree architecture is crucial to maximizing light capture, determined by carbon allocation of individual trees, and consequently characterizes species-specific growth strategies. Its variation and associated life-history strategies have been examined in tropical and temperate forests, but not in subtropical forests. Moreover, a similar architectural pattern was found using a hierarchical Bayesian model in a tropical forest, which differed from most of previous studies. Here, we employed a hierarchical Bayesian model to examine tree architecture differences and associations with adult stature and light requirement among 59 subtropical co-occurring species. Architectural variations among tree species with different seed dispersal and leaf phenology types were analyzed. Most species showed similar architecture in the height of the lowest foliage-tree height relationships (F-H) and the long side of crown- tree height relationships (W1-H), but some species showed interspecific variations in tree height-stem diameter relationships (H-D) among the 59 co-occurring species in the subtropical montane forest. Trees developed deeper and larger crowns at mid-elevation compared to the tropical and temperate forests. Parameters of H-D relationship differed in leaf phenology and dispersal types, and intercepts of F-H relationship and W1-H relationship differed in leaf phenology. Large-statured species had more slender stems, and shallower and narrower crowns at small sizes, but similar crowns at large sizes. Light-demanding species showed weak correlations between architectural variables and light requirement but exhibited wide crowns at the intermediate sizes. In general, size-dependent architectural differentiation was driven mainly by adult stature and light requirement in subtropical forest. Coexistence species showed different life-history strategies in light capture, which may help provide options in forest thinning and harvesting in subtropical forest. Species-specific tree architectural models of 59 co-occurring species represent three-dimensional (3D) structure of this subtropical forest accurately, but also support for future terrestrial laser scanning (TLS) data analysis.
Display omitted
•Relation of taxonomic and phylogenetic diversity differ between common and rare species.•Shrubland diversity showed a clear longitude pattern.•Phylogenetic relatedness can explain ...deviations in taxonomic and phylogenetic diversity.•Environmental drivers varied among facets of biodiversity as well as species with different abundance.
Interpreting biodiversity patterns and the underlying processes is crucial for evaluating the mechanisms of community assembly, but the view of multifaceted diversity patterns spanning broad spatial extents is less strengthened. We implemented an inventory of 1260 vegetation plots from shrublands across China with standardized methods and analyzed patterns of taxonomic and phylogenetic diversity with differential weighting of common and rare species, as well as phylogenetic co-occurrence structures. Taxonomic and phylogenetic diversity were linearly correlated when common and rare species were weighted equally, but had a logarithmic correlation when species were weighted with their relative abundances. While most shrubland communities were phylogenetically unstructured, the correlation between taxonomic and phylogenetic diversity covaried with phylogenetic relatedness when incorporating relative abundance, but only weakly so in phylogenetically over-dispersed communities. When we correlated patterns of taxonomic and phylogenetic diversity with different weightings for common versus rare species, we found an important role for geographic (e.g., longitude, altitude), climatic (temperature, precipitation) and soil factors. The importance of underlying variables varied between facets of diversity. We found a strong role for altitude in taxonomic, but less so for phylogenetic diversity. Furthermore, the importance of several environmental drivers varied depending on whether diversity metrics were strongly influenced by rare species or put more weight on common and/or dominant species. Overall, our assessment highlights the importance of synthetic analyses of patterns and processes of different facets of biodiversity to capture the full complexity of diversity in conservation studies.
Ecological theory suggests that species with complementary architectural and physiological traits can optimize crown packing to improve resource efficiency and promote ecosystem productivity in ...forest communities. However, empirical evidence of this prediction is rare in species-rich natural forests, as little is known about how crown spatial complementarity regulates community species richness-productivity relationship (SRPR). In this study, we measured tree architectural traits (stem diameter, height, crown depth and width) for 11,337 trees, and quantified species richness, functional diversity, crown spatial complementarity, soil fertility and forest productivity for 44 quadrats (20 m × 20 m per quadrat) in the Badagongshan 25 ha forest plot, central China. We tested bivariate correlations between species richness, crown complementarity, functional diversity and forest productivity. We employed linear mixed effects models to predict crown complementarity and examined its relationship with functional diversity. Finally, we applied structural equation modeling to quantify the mediation effects of crown complementarity on SRPRs. Species richness promoted crown complementarity and forest productivity. Crown complementarity varied across quadrats, with increases driven primarily by changes in tree height. Crown complementarity was positively related to functional diversity and forest productivity. Species richness increased with soil total phosphorus, while functional diversity decreased with soil bulk density. Forest productivity increased with soil organic carbon and total nitrogen, but decreased with bulk density. Crown complementarity partially mediated the positive effect of species richness on forest productivity, and the mediation effect was mainly through functional diversity. Our results suggest that the crown complementarity index accurately reflects the niche complementarity through light utilization and carbon reallocation. Our study emphasizes that species richness can promote crown complementarity, leading to greater forest productivity, which provides greater insight into the mechanical understanding of the SRPRs.
Aim
Wuling Mountains range from the northeast to southwest in Central China, a region with high habitat complexity and diversity that supports substantial plant species diversity. Connecting the ...northern subtropics to the mid-subtropics, Wuling Mountains also link the floras of Eastern and South-Western China. Despite a long-standing interest in how important role Wuling Mountains play in species exchange, patterns of plant species diversity in Wuling and their underlying drivers are still not well characterized. Here, the spatial distribution of woody plant species in this region is described and the role the Wuling Mountains play in structuring biodiversity in surrounding areas is explored.
Location
Wuling Mountains and adjacent regions, China.
Methods
Detailed distribution data for woody plant species in China were collected and mapped onto a raster grid of the Wuling Mountains and adjacent regions (a total of 820,000 km
2
) to analyze spatial patterns in species diversity, including α-diversity (species richness) and β-diversity (β
sor
). Unweighted pair-group method using arithmetic averages (UPGMA) clustering was used to divide the study region based on species composition. Canonical redundancy analysis was used to illustrate spatial patterns and species-environment relationships.
Results
Mountainous areas in the study region have high species richness as compared to other areas. Species exchanges occurred at a greater rate latitudinally vs. longitudinally, especially in Wuling Mountains. This suggests that Wuling Mountains may be an important ecological corridor for woody species, linking Northern and Southern Chinese floras. The study region was divided into six bioregions based on species composition: the Wuling Mountains Region, Nanling-Xuefengshan Mountains Region, Qinling-Dabashan Mountains Region, Sichuan Basin Region, Yangtze Plain Region and Yungui Plateau Region.
Main Conclusions
The Wuling Mountains Region acts as an ecological corridor for woody species, linking Northern and Southern China, and fostering biodiversity exchange and conservation in Central China.
Inferring the processes underlying the spatial distribution patterns of tree species is fundamental for understanding species coexistence. Here, we examined spatial distribution patterns of woody ...plants by using the univariate pair correlation function to quantify spatial patterns of species in a fullly mapped 25 ha subtropical plot in China. We analyzed the relationships between the species attributes and spatial distribution patterns of 137 tree species with at least one individual per hectare. The results showed that aggregated distributions were the dominant pattern for species in the Badagongshan subtropical forests, and that the percentage of significantly aggregated species decreased with increasing spatial scales. Rare species were more aggregated than intermediate and abundant species, but they were more easily influenced by habitat heterogeneity. Also, there was significantly negative relationship between species abundance and species aggregation intensity. The aggregation intensity showed negative relationships to species mean diameter at breast height (DBH) and maximum DBH, i.e., species became more regularly spaced as species stature increased. Species functional traits (e.g., growth form and phenological guild) also had obvious effects on the spatial patterns of species. However, spatial patterns of tree species were not related to the dispersal mode. Our results partially conformed to the prediction that species’ attributes influenced species’ spatial patterns following similar laws, even after controlling for the effects of habitat heterogeneity. Consequently, species attributes (species abundance, mean DBH, maximal DBH, growth form, phenological guild, etc.) and habitat heterogeneity may primarily contribute to spatial patterns and species coexistence in natural forests.
Subtropical forests are important carbon sinks and have a huge potential for mitigating climate change. However, few studies have developed biomass models to give robust estimates of subtropical ...forest aboveground and belowground biomass. Although wood density (WD) can greatly reduce the uncertainty in aboveground biomass (AGB) estimates in tropical forest, it has never been applied in other ecosystems. In addition, crowns hold a large component of tree biomass and vary among forest types, so crown dimensions as new variables have been recommended for AGB models. To test the role of wood density and crown dimensions and to select the best AGB model in subtropical forest, we harvested and weighted dry mass of 147 trees from 41 dominant species in subtropical forest. In order to account the belowground biomass (BGB) of these forests, 23 roots systems were excavated following aboveground harvest. Models with wood density performed better than all those without wood density, and models with height performed better than those without height, indicating wood density and tree height (
H
) are crucial factors in AGB models of subtropical forest. Adding crown radius (CR) did not improve the model performance. The BGB models with diameter at breast (DBH) in power form were significant (***
p
< 0.001). The new AGB models presented here, with wood density and tree height, and BGB models substantially improve biomass estimates in subtropical forest.
Accumulating evidence suggests that density dependence, whether at early or late life stages, is an important mechanism regulating plant population structure. However, the opposing effects of habitat ...heterogeneity and species-level variation might have confounded the prevalence of density dependence in natural forests. These compatible ideas were rarely considered simultaneously. In this study, we applied a spatial statistical technique to examine (i) the prevalence of density dependence at late life stages after controlling for habitat heterogeneity and (ii) the relationships between species traits and the strength of density dependence in a newly established, 25 ha subtropical mountain forest plot in central China. Of the 88 (75%) tree species analyzed, 66 were found to exhibit density dependence predominantly at very close distances among neighbors in the species-rich subtropical forest. In addition, the strength of density dependence was associated with species traits. Our findings identified strong density dependence among trees that had greater stature and were rarer. We concluded that density dependence was a prevalent mechanism for regulating the population structure of most tree species and both habitat heterogeneity and species-level variation played crucial roles in shaping the strength of density dependence in natural forests.
The stochastic dilution hypothesis has been proposed to explain species coexistence in species-rich communities. The relative importance of the stochastic dilution effects with respect to other ...effects such as competition and habitat filtering required to be tested. In this study, using data from a 25-ha species-rich subtropical forest plot with a strong topographic structure at Badagongshan in central China, we analyzed overall species associations and fine-scale species interactions between 2,550 species pairs. The result showed that: (1) the proportion of segregation in overall species association analysis at 2 m neighborhood in this plot followed the prediction of the stochastic dilution hypothesis that segregations should decrease with species richness but that at 10 m neighborhood was higher than the prediction. (2) The proportion of no association type was lower than the expectation of stochastic dilution hypothesis. (3) Fine-scale species interaction analyses using Heterogeneous Poisson processes as null models revealed a high proportion (47%) of significant species effects. However, the assumption of separation of scale of this method was not fully met in this plot with a strong fine-scale topographic structure. We also found that for species within the same families, fine-scale positive species interactions occurred more frequently and negative ones occurred less frequently than expected by chance. These results suggested effects of environmental filtering other than species interaction in this forest. (4) We also found that arbor species showed a much higher proportion of significant fine-scale species interactions (66%) than shrub species (18%). We concluded that the stochastic dilution hypothesis only be partly supported and environmental filtering left discernible spatial signals in the spatial associations between species in this species-rich subtropical forest with a strong topographic structure.
In contrast to the depth of knowledge available for the enhancement of plant species diversity and ecosystem services through ecological restoration, our understanding of how ecological restoration ...impacts genetic diversity (GD) of plant species has not yet been synthesized.
We performed a global meta‐analysis to examine whether ecological restoration improved GD of plant species in restored populations. First, we compared the GD of restored populations with reference or degraded populations. Second, we explored whether the influence of ecological restoration on plant GD varies between species with different characteristics (life form and threat status), between different restoration strategies (active/passive, seeding/planting, mixture/non‐mixture) or between different restoration times (<50 and ≥ 50 years; with an average of 29.3 years).
The GD of restored populations was significantly lower (HE, 1.06%; PPB, 5.10%, and SWI, 4.95%) than in reference populations but was comparable to degraded populations. The inbreeding coefficient (FIS, the proportion by which the heterozygosity of an individual is reduced by inbreeding) was consistently comparable between restored populations and reference or degraded populations.
Woody species but not herbs and forest but not grassland ecosystem had significantly lower GD in restored populations than in reference populations. Passive but not active restoration, seeding rather than planting, and mixing materials from different sources rather than using a single source, all significantly increased the GD of restored populations. When the restoration time was ≥50 years, in contrast to <50 years, GD was comparable between the restored and reference populations.
Synthesis and applications. In general, ecological restoration did not significantly improve the GD of plant species compared to reference or degraded populations. This might be due in part to the relatively short restoration time. Using passive restoration, seeding, and mixed sources could significantly increase the GD of restored populations. We emphasize that GD should not be treated as a minor cobenefit of ecological restoration for other purposes and that the recovery of GD should be listed as a vital goal in future ecological restoration with plant species.
摘要
虽然生态恢复对植物物种多样性和生态系统服务的促进作用已得到深入的研究和综述，但是生态恢复对植物遗传多样性的恢复效果尚未得到系统的总结。
本研究采用Meta分析来揭示全球范围内生态恢复是否促进被恢复植物种群的遗传多样性。首先，我们比较了被恢复植物种群与参照或退化种群的遗传多样性。其次，我们探索了植物特性(生活型和受威胁状况)、恢复策略(主动与被动修复、直接播种与活体种植、多种源与单种源)和恢复时间(小于与不小于50年；平均恢复时间为29.3年)对植物遗传多样性恢复效果的影响。
被恢复植物种群的遗传多样性显著低于参照种群(预期杂合度HE，低1.06%；多态性位点百分比PPB，5.10%；香农‐维纳指数SWI，4.95%)，但是与退化种群相当。被恢复植物种群的近交系数(FIS)与参照和退化种群均相当。
木本而非草本植物、森林而非草地生态系统的被恢复植物种群的遗传多样性显著低于参照种群。被动而非主动恢复、直接播种而非活体种植、多种源混合而非单种源可以显著提高被恢复植物种群的遗传多样性。当恢复时间小于50年时，被恢复植物种群的遗传多样性显著低于参照种群，而当恢复时间大于等于50年时，被恢复种群的遗传多样性与参照种群相当。
总的来说，与参照和退化种群相比，生态恢复并未显著提高被恢复植物种群的遗传多样性，部分原因可能是生态恢复时间相对较短。在条件允许的情况下，采用被动恢复、直接播种和多种源混合的策略可以显著提高被恢复植物种群的遗传多样性。本研究强调，在未来涉及植物的生态恢复中，需将植物种群的遗传多样性恢复作为一个重要目标。
In general, ecological restoration did not significantly improve the GD of plant species compared to reference or degraded populations. This might be due in part to the relatively short restoration time. Using passive restoration, seeding, and mixed sources could significantly increase the GD of restored populations. We emphasize that GD should not be treated as a minor cobenefit of ecological restoration for other purposes and that the recovery of GD should be listed as a vital goal in future ecological restoration with plant species.
PDF
