Limits...
Using Plant Functional Traits and Phylogenies to Understand Patterns of Plant Community Assembly in a Seasonal Tropical Forest in Lao PDR.

Satdichanh M, Millet J, Heinimann A, Nanthavong K, Harrison RD - PLoS ONE (2015)

Bottom Line: Although there was strong evidence that an underlying soil gradient was determining patterns of species composition at the site, our results did not support the hypothesis that the environmental filtering dominated community assembly processes.Nevertheless, our results are equivocal and other interpretations are possible.Our study illustrates some difficulties in combining trait and phylogenetic approaches that may result from the complexities of integrating spatial and evolutionary processes that vary at different scales.

View Article: PubMed Central - PubMed

Affiliation: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, P.R. China; University of the Chinese Academy of Sciences, Beijing, P.R. China; Faculty of Forestry Science, National University of Laos, Dongdok Campus, Vientiane, Lao PDR.

ABSTRACT
Plant functional traits reflect different evolutionary responses to environmental variation, and among extant species determine the outcomes of interactions between plants and their environment, including other plant species. Thus, combining phylogenetic and trait-based information can be a powerful approach for understanding community assembly processes across a range of spatial scales. We used this approach to investigate tree community composition at Phou Khao Khouay National Park (18°14'-18°32'N; 102°38'- 102°59'E), Laos, where several distinct forest types occur in close proximity. The aim of our study was to examine patterns of plant community assembly across the strong environmental gradients evident at our site. We hypothesized that differences in tree community composition were being driven by an underlying gradient in soil conditions. Thus, we predicted that environmental filtering would predominate at the site and that the filtering would be strongest on sandier soil with low pH, as these are the conditions least favorable to plant growth. We surveyed eleven 0.25 ha (50x50 m) plots for all trees above 10 cm dbh (1221 individual trees, including 47 families, 70 genera and 123 species) and sampled soils in each plot. For each species in the community, we measured 11 commonly studied plant functional traits covering both the leaf and wood economic spectrum traits and we reconstructed a phylogenetic tree for 115 of the species in the community using rbcL and matK sequences downloaded from Genebank (other species were not available). Finally we compared the distribution of trait values and species at two scales (among plots and 10x10m subplots) to examine trait and phylogenetic community structures. Although there was strong evidence that an underlying soil gradient was determining patterns of species composition at the site, our results did not support the hypothesis that the environmental filtering dominated community assembly processes. For the measured plant functional traits there was no consistent pattern of trait dispersion across the site, either when traits were considered individually or when combined in a multivariate analysis. However, there was a significant correlation between the degree of phylogenetic dispersion and the first principle component axis (PCA1) for the soil parameters. Moreover, the more phylogenetically clustered plots were on sandier soils with lower pH. Hence, we suggest that the community assembly processes across our site may reflect the influence of more conserved traits that we did not measure. Nevertheless, our results are equivocal and other interpretations are possible. Our study illustrates some difficulties in combining trait and phylogenetic approaches that may result from the complexities of integrating spatial and evolutionary processes that vary at different scales.

No MeSH data available.


Correlation between local community phylogenetic structure and soil parameters (PCA axis 1) for 11 plots at PKK.Both relative abundance and basal area weighted values were significantly correlated with the first soil PCA axis (r = 0.82, P = 0.001 and r = 0.62, P = 0.002). There was no significant correlation between either of the phylogenetic dispersion patterns and PCA2 (not shown). Filled circles show significant values of NRI at the plot level (± 1.96; P<0.05). PCA1 explained 59% of the variance in soil parameters.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4482738&req=5

pone.0130151.g003: Correlation between local community phylogenetic structure and soil parameters (PCA axis 1) for 11 plots at PKK.Both relative abundance and basal area weighted values were significantly correlated with the first soil PCA axis (r = 0.82, P = 0.001 and r = 0.62, P = 0.002). There was no significant correlation between either of the phylogenetic dispersion patterns and PCA2 (not shown). Filled circles show significant values of NRI at the plot level (± 1.96; P<0.05). PCA1 explained 59% of the variance in soil parameters.

Mentions: Across the 11 plots, community phylogenetic structure weighted by relative abundance (NRI.RA) was clustered in four plots and over-dispersed in seven plots. However, in only one plot was it significantly clustered and in only two plots was it significantly over-dispersed (NRI ± 1.96). NRI weighted by basal area (NRI.BA) was clustered in six plots and over-dispersed in five plots but none of NRI.BA values were significantly different from zero. However, phylogenetic structure for both basal area and relative abundance weightings was significantly correlated with soil PCA1 (r > 0.8, P = 0.001, r > 0.62, P = 0.002, respectively) (Fig 3), but not PCA2.


Using Plant Functional Traits and Phylogenies to Understand Patterns of Plant Community Assembly in a Seasonal Tropical Forest in Lao PDR.

Satdichanh M, Millet J, Heinimann A, Nanthavong K, Harrison RD - PLoS ONE (2015)

Correlation between local community phylogenetic structure and soil parameters (PCA axis 1) for 11 plots at PKK.Both relative abundance and basal area weighted values were significantly correlated with the first soil PCA axis (r = 0.82, P = 0.001 and r = 0.62, P = 0.002). There was no significant correlation between either of the phylogenetic dispersion patterns and PCA2 (not shown). Filled circles show significant values of NRI at the plot level (± 1.96; P<0.05). PCA1 explained 59% of the variance in soil parameters.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482738&req=5

pone.0130151.g003: Correlation between local community phylogenetic structure and soil parameters (PCA axis 1) for 11 plots at PKK.Both relative abundance and basal area weighted values were significantly correlated with the first soil PCA axis (r = 0.82, P = 0.001 and r = 0.62, P = 0.002). There was no significant correlation between either of the phylogenetic dispersion patterns and PCA2 (not shown). Filled circles show significant values of NRI at the plot level (± 1.96; P<0.05). PCA1 explained 59% of the variance in soil parameters.
Mentions: Across the 11 plots, community phylogenetic structure weighted by relative abundance (NRI.RA) was clustered in four plots and over-dispersed in seven plots. However, in only one plot was it significantly clustered and in only two plots was it significantly over-dispersed (NRI ± 1.96). NRI weighted by basal area (NRI.BA) was clustered in six plots and over-dispersed in five plots but none of NRI.BA values were significantly different from zero. However, phylogenetic structure for both basal area and relative abundance weightings was significantly correlated with soil PCA1 (r > 0.8, P = 0.001, r > 0.62, P = 0.002, respectively) (Fig 3), but not PCA2.

Bottom Line: Although there was strong evidence that an underlying soil gradient was determining patterns of species composition at the site, our results did not support the hypothesis that the environmental filtering dominated community assembly processes.Nevertheless, our results are equivocal and other interpretations are possible.Our study illustrates some difficulties in combining trait and phylogenetic approaches that may result from the complexities of integrating spatial and evolutionary processes that vary at different scales.

View Article: PubMed Central - PubMed

Affiliation: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, P.R. China; University of the Chinese Academy of Sciences, Beijing, P.R. China; Faculty of Forestry Science, National University of Laos, Dongdok Campus, Vientiane, Lao PDR.

ABSTRACT
Plant functional traits reflect different evolutionary responses to environmental variation, and among extant species determine the outcomes of interactions between plants and their environment, including other plant species. Thus, combining phylogenetic and trait-based information can be a powerful approach for understanding community assembly processes across a range of spatial scales. We used this approach to investigate tree community composition at Phou Khao Khouay National Park (18°14'-18°32'N; 102°38'- 102°59'E), Laos, where several distinct forest types occur in close proximity. The aim of our study was to examine patterns of plant community assembly across the strong environmental gradients evident at our site. We hypothesized that differences in tree community composition were being driven by an underlying gradient in soil conditions. Thus, we predicted that environmental filtering would predominate at the site and that the filtering would be strongest on sandier soil with low pH, as these are the conditions least favorable to plant growth. We surveyed eleven 0.25 ha (50x50 m) plots for all trees above 10 cm dbh (1221 individual trees, including 47 families, 70 genera and 123 species) and sampled soils in each plot. For each species in the community, we measured 11 commonly studied plant functional traits covering both the leaf and wood economic spectrum traits and we reconstructed a phylogenetic tree for 115 of the species in the community using rbcL and matK sequences downloaded from Genebank (other species were not available). Finally we compared the distribution of trait values and species at two scales (among plots and 10x10m subplots) to examine trait and phylogenetic community structures. Although there was strong evidence that an underlying soil gradient was determining patterns of species composition at the site, our results did not support the hypothesis that the environmental filtering dominated community assembly processes. For the measured plant functional traits there was no consistent pattern of trait dispersion across the site, either when traits were considered individually or when combined in a multivariate analysis. However, there was a significant correlation between the degree of phylogenetic dispersion and the first principle component axis (PCA1) for the soil parameters. Moreover, the more phylogenetically clustered plots were on sandier soils with lower pH. Hence, we suggest that the community assembly processes across our site may reflect the influence of more conserved traits that we did not measure. Nevertheless, our results are equivocal and other interpretations are possible. Our study illustrates some difficulties in combining trait and phylogenetic approaches that may result from the complexities of integrating spatial and evolutionary processes that vary at different scales.

No MeSH data available.