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1.
Commun Biol ; 2: 277, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31372516

RESUMO

Negative distance-dependence of conspecific seedling mortality (NDisDM) is a crucial stabilizing force that regulates plant diversity, but it remains unclear whether and how fragment size shifts the strength of NDisDM. Here, we surveyed the seed‒seedling transition process for a total of 25,500 seeds of a local dominant tree species on islands of various sizes in a reservoir and on the nearby mainland. We found significant NDisDM on the mainland and large and medium islands, with significantly stronger NDisDM on medium islands. However, positive distance-dependent mortality was detected on small islands. Changes in distance-dependence were critically driven by both rodent attack and pathogen infestation, which were significantly affected by fragment size. Our results emphasize the necessity of incorporating the effects of fragment size on distance-dependent regeneration of dominant plant species into the existing frameworks for better predicting the consequences of habitat fragmentation.

2.
Oecologia ; 190(3): 629-637, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31214834

RESUMO

Species with large intraspecific trait variability (ITV) have larger niche breadth than species with low ITV and thus are expected to be more abundant at the local scale. However, whether the positive ITV-abundance relationship holds in heterogeneous local environments remains uncertain. Using an individual-based trait dataset encompassing three leaf traits (leaf area, specific leaf area, and leaf dry mass content) of 20,248 individuals across 80 species in an environmentally heterogeneous subtropical forest in eastern China, ITV for each trait of each species was estimated by rarefaction. Resource-based niche breadth and marginality (the absolute distance between the mean resource states used by a species and the mean plot-wise resource states) were estimated simultaneously by the K-S method and the outlying mean index, respectively. Species with moderate ITV were often locally abundant, while species with large or small ITV were locally rare. This unimodal relationship between ITV and species abundance persisted when traits were analyzed separately and for all tree size classes. There was also a hump-backed relationship between niche breadth and marginality, and ITV was positively associated with niche breadth. The combined results suggest either a trade-off between the benefit from expanding niche breadth to adapt to multiple habitats and the disadvantage of reducing competitive ability, or a scarcity of favorable resources. Our results do not support the traditional thought that ITV positively correlates with species abundance in heterogeneous local environments. Instead, our study suggests that moderate-rather than large-intraspecific trait variability increases species abundance at local scales.


Assuntos
Florestas , Árvores , China , Ecossistema , Fenótipo
3.
Ecol Lett ; 22(2): 245-255, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30548766

RESUMO

Climate is widely recognised as an important determinant of the latitudinal diversity gradient. However, most existing studies make no distinction between direct and indirect effects of climate, which substantially hinders our understanding of how climate constrains biodiversity globally. Using data from 35 large forest plots, we test hypothesised relationships amongst climate, topography, forest structural attributes (stem abundance, tree size variation and stand basal area) and tree species richness to better understand drivers of latitudinal tree diversity patterns. Climate influences tree richness both directly, with more species in warm, moist, aseasonal climates and indirectly, with more species at higher stem abundance. These results imply direct limitation of species diversity by climatic stress and more rapid (co-)evolution and narrower niche partitioning in warm climates. They also support the idea that increased numbers of individuals associated with high primary productivity are partitioned to support a greater number of species.


Assuntos
Biodiversidade , Árvores , Clima
4.
R Soc Open Sci ; 5(9): 181168, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30839691

RESUMO

The relationship between ß-diversity and latitude still remains to be a core question in ecology because of the lack of consensus between studies. One hypothesis for the lack of consensus between studies is that spatial scale changes the relationship between latitude and ß-diversity. Here, we test this hypothesis using tree data from 15 large-scale forest plots (greater than or equal to 15 ha, diameter at breast height ≥ 1 cm) across a latitudinal gradient (3-30o) in the Asia-Pacific region. We found that the observed ß-diversity decreased with increasing latitude when sampling local tree communities at small spatial scale (grain size ≤0.1 ha), but the observed ß-diversity did not change with latitude when sampling at large spatial scales (greater than or equal to 0.25 ha). Differences in latitudinal ß-diversity gradients across spatial scales were caused by pooled species richness (γ-diversity), which influenced observed ß-diversity values at small spatial scales, but not at large spatial scales. Therefore, spatial scale changes the relationship between ß-diversity, γ-diversity and latitude, and improving sample representativeness avoids the γ-dependence of ß-diversity.

5.
Sci Rep ; 6: 37830, 2016 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-27886275

RESUMO

Conspecific adults have strong negative effect on the survival of nearby early-stage seedlings and thus can promote species coexistence by providing space for the regeneration of heterospecifics. The leaf litter fall from the conspecific adults, and it could mediate this conspecific negative adult effect. However, field evidence for such effect of conspecific leaf litter remains absent. In this study, we used generalized linear mixed models to assess the effects of conspecific leaf litter on the early-stage seedling survival of four dominant species (Machilus leptophylla, Litsea elongate, Acer pubinerve and Distylium myricoides) in early-stage seedlings in a subtropical evergreen broad-leaved forest in eastern China. Our results consistently showed that the conspecific leaf litter of three species negatively affected the seedling survival. Meanwhile, the traditional conspecific adult neighborhood indices failed to detect this negative conspecific adult effect. Our study revealed that the accumulation of conspecific leaf litter around adults can largely reduce the survival rate of nearby seedlings. Ignoring it could result in underestimation of the importance of negative density dependence and negative species interactions in the natural forest communities.


Assuntos
Folhas de Planta/crescimento & desenvolvimento , Plântula/fisiologia , Acer/fisiologia , Ecossistema , Florestas , Hamamelidaceae/fisiologia , Lauraceae/fisiologia , Densidade Demográfica
6.
PLoS One ; 11(5): e0156326, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27227538

RESUMO

The pervasive pattern of aggregated tree distributions in natural communities is commonly explained by the joint effect of two clustering processes: environmental filtering and dispersal limitation, yet little consensus remains on the relative importance of the two clustering processes on tree aggregations. Different life stages of examined species were thought to be one possible explanation of this disagreement, because the effect of environmental filtering and dispersal limitation are expected to increase and decrease with tree life stages, respectively. However, few studies have explicitly tested these expectations. In this study, we evaluated these expectations by three different methods (species-habitat association test based on Poisson Clustering model and spatial point pattern analyses based on Heterogeneous Poisson model and the jointly modeling approach) using 36 species in a 20-ha subtropical forest plot. Our results showed that the percentage of species with significant habitat association increased with life stages, and there were fewer species affected by dispersal limitation in later life stages compared with those in earlier stages. Percentage of variance explained by the environmental filtering and dispersal limitation also increases and decreases with life stages. These results provided a promising alternative explanation on the existing mixed results about the relative importance of the two clustering processes. These findings also highlighted the importance of plant life stages for fully understanding species distributions and species coexistence.


Assuntos
Meio Ambiente , Modelos Teóricos , Dispersão Vegetal/fisiologia , Árvores/fisiologia , Análise por Conglomerados , Ecossistema , Florestas , Densidade Demográfica , Especificidade da Espécie , Árvores/classificação , Clima Tropical
7.
Ecology ; 94(11): 2436-43, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24400495

RESUMO

Spatially explicit consideration of species distribution can significantly add to our understanding of species coexistence. In this paper, we evaluated the relative importance of habitat heterogeneity and other clustering processes (e.g., dispersal limitation, collectively called the non-habitat clustering process) in explaining the spatial distribution patterns of 341 tree species in three stem-mapped 25-50 ha plots of tropical, subtropical, and temperate forests. Their relative importance was estimated by a method that can take one mechanism into account when estimating the effects of the other mechanism and vice versa. Our results demonstrated that habitat heterogeneity was less important in explaining the observed species patterns than other clustering processes in plots with flat topography but was more important in one of the three plots that had a complex topography. Meanwhile, both types of clustering mechanisms (habitat or non-habitat) were pervasive among species at the 50-ha scale across the studied plots. Our analyses also revealed considerable variation among species in the relative importance of the two types of mechanism within each plot and showed that this species-level variation can be partially explained by differences in dispersal mode and growth form of species in a highly heterogeneous environment. Our findings provide new perspectives on the formation of species clustering. One important finding is that a significant species-habitat association does not necessarily mean that the habitat heterogeneity has a decisive influence on species distribution. The second insight is that the large species-level variation in the relative importance of the two types of clustering mechanisms should not be ignored. Non-habitat clustering processes can play an important role on species distribution.


Assuntos
Ecossistema , Árvores/fisiologia , Análise por Conglomerados , Demografia , Especificidade da Espécie , Árvores/classificação , Árvores/genética
8.
Ying Yong Sheng Tai Xue Bao ; 22(5): 1295-301, 2011 May.
Artigo em Chinês | MEDLINE | ID: mdl-21812309

RESUMO

Five evergreen broad-leaved forests (one continuous forest and four fragmented forests) in the mountain areas in the juncture of Zhejiang, Fujian, and Jiangxi Provinces, East China were selected as test objects to study the dynamics of soil arthropod community structure and its responses to forest fragmentation during the decomposition of dominant tree species Castanopsis eyrei leaf litter. A total of 899 soil arthropods were collected, belonging to 9 classes and 25 orders. Lepidoptera was the dominant taxon, accounting for 10% of the individual, while Hymenoptera, Collembola, Diptera, Prostigmata, and Geophilomorpha were the common taxa. The decomposition rate of C. eyrei leaf litter was the highest in August and lower in April-June and December, which was in accordance with the seasonal dynamics of the taxa number and individual number of soil arthropods. Meanwhile, the taxa number, individual number, and species diversity of soil arthropods differed between continuous forest and fragmented forests, suggesting that both area effect and edge effect affected the dynamics of soil arthropod community structure during the decomposition of C. eyrei leaf litter.


Assuntos
Artrópodes/classificação , Ecossistema , Fagaceae/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Animais , Artrópodes/metabolismo , China , Fagaceae/química , Fagaceae/metabolismo , Agricultura Florestal , Folhas de Planta/química , Dinâmica Populacional , Solo/análise , Árvores/crescimento & desenvolvimento
9.
Ying Yong Sheng Tai Xue Bao ; 21(2): 265-71, 2010 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-20461992

RESUMO

Taking four evergreen broad-leaved forest fragments within the adjacent mountainous region of Zhejiang, Fujian, and Jiangxi provinces as study objects, and the continuous forest in Gutianshan National Natural Reserve as the control, an investigation was made by litter bag method from June 2004 to April 2006, aimed to understand the community structure and its dynamics change of soil meso-micro arthropods during the decomposition of Schima superba leaf litter. A total of 1050 soil meso-micro arthropods belonging to 8 classes and 23 orders were collected, among which, Lepidoptera, Hymenoptera, Collembola and Diptera were the dominant taxa. The impact of habitat fragmentation on the community composition of soil arthropods was mainly manifested in the differences of rare taxa, and the dominance of different taxa at different decomposition stages of S. superba leaf litter varied with the functions of the taxa in litter decomposition. After two-year decomposition, the mass loss of S. superba leaf litter was 60%-70%, and the species diversity indices of soil arthropods showed certain changes, being different between forest fragments and continuous forest.


Assuntos
Artrópodes/classificação , Ecossistema , Theaceae/crescimento & desenvolvimento , Animais , Artrópodes/fisiologia , Biodiversidade , China , Folhas de Planta/química , Folhas de Planta/metabolismo , Dinâmica Populacional , Solo/análise
10.
Ecology ; 90(11): 3033-41, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19967859

RESUMO

Species-area relationships (SARs) characterize the spatial distribution of species diversity in community ecology, but the biological mechanisms underlying the SARs have not been fully explored. Here, we examined the roles of dispersal limitation and habitat heterogeneity in shaping SARs in two large-scale forest plots. One is a 24-ha subtropical forest in Gutianshan National Nature Reserve, China. The other is a 50-ha tropical rain forest in Barro Colorado Island, Panama. Spatial point pattern models were applied to investigate the contributions of dispersal and habitat heterogeneity and their interactions to the formation of the SARs in the two sites. The results showed that, although dispersal and habitat heterogeneity each could significantly contribute to the SARs, each alone was insufficient to explain the SARs. Their joint effects sufficiently explained the real SARs, suggesting that heterogeneous habitat and dispersal limitation are two predominant mechanisms for maintaining the spatial distributions of the species in these two forests. These results add to our understanding of the ecological processes underlying the spatial variation of SARs in natural forest communities.


Assuntos
Ecossistema , Animais , China , Simulação por Computador , Demografia , Geografia , Modelos Biológicos , Panamá , Distribuição de Poisson , Clima Tropical
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