Partitioning the variation of woody plant β‐diversity in a landscape of secondary tropical dry forests across spatial scales

Abstract

Question What is the relative importance of forest successional age, environmental heterogeneity, landscape structure and spatial structure of sampling sites on β‐diversity of tropical dry forests (TDF)? How do the magnitude of β‐diversity and the relative influence of factors, processes and mechanisms driving β‐diversity differ at different spatial grains? What are the effects of stand age on β‐diversity? Location Yucatán Peninsula, México. Methods Floristic composition was obtained from a hierarchical survey performed in 276 sites distributed across 23 sampling landscapes (SL) (12 sites per SL). Land‐cover classes were derived from the classification of multi‐spectral SPOT 5 satellite imagery. We calculated landscape metrics of patch type for each SL, and characterized local soil conditions for each sampling site. A principal coordinates of neighbour matrices (PCNM) analysis was performed to estimate spatial variables, and partial redundancy analysis was used to decompose variation into spatial, stand age and landscape structure components. Results The magnitude of β‐diversity varied with spatial scale (grain size), and was larger at the local than at the landscape grain. The magnitude of β‐diversity also decreased slightly but significantly with successional age. There were significant differences in species composition among vegetation classes. Environmental factors (local soil conditions, as well as landscape structure) and spatial structure both contributed to woody plant β‐diversity in our TDF landscape, but their relative importance was scale‐dependent. At the local grain size, both the environment (mainly soil conditions) and the spatial structure strongly affected β‐diversity, while at the landscape grain, environmental factors (variation in soil conditions, as well as landscape configuration) played a more prominent role. Conclusions The magnitude of β‐diversity decreased with increasing spatial grain and successional age, while the relative importance of mechanisms influencing β‐diversity was scale‐dependent: both niche partitioning and dispersal limitation affect β‐diversity at the local grain size, while niche partitioning prevails at the landscape grain.

Humidity, low temperature extremes, and space influence floristic variation across an insightful gradient in the Subtropical Atlantic Forest

“…López-Martínez et al (2013) observed significant values for environmental variables and spatial structure, and they interpreted these results as a proxy for both niche partitioning (environment variables) and dispersal limitation (spatial structure), despite the limitations of the approach (Diniz-Filho et al 2012). Based on our findings, spatial effects may be due to topographical variations in the region, as they generate high spatial variability in environmental variables and could serve as physical or climatic barriers to species dispersal.…”

β-Diversity of Functional Groups of Woody Plants in a Tropical Dry Forest in Yucatan

“…Similarly, stand age explained less than 10% of variation in species composition of zoochorous and autochorous species, and 20% of the anemochorous β-diversity. In this same study area, [14] found that stand age explained only 3% of the total variation in species composition of all woody species. These contrasting results clearly illustrate the importance of considering different functional groups when evaluating the ecological factors that influence β-diversity.…”

“…This may be partly attributed to their relatively short stature, which may impose critical limits on their dispersal capacity, resulting in a strong spatial autocorrelation in species composition. Using the same data set and (local) spatial grain of this study, [14] found that both environmental variables and the spatial structure of sampling sites had similar influences on overall β-diversity of woody species. Our results clearly show that this general pattern masks major differences in the relative importance of environmental filters vs. dispersal limitation among growth forms.…”

“…For example, previous studies have shown that the magnitude of β-diversity is influenced by secondary succession [14], soil properties [1], [2], [15], [16], fragmentation [17] and topography [18]. These factors produce changes in community patterns by modifying the local environment and resource availability [19], hence creating opportunities for the establishment of new species and reducing populations of those that are already established (see reviews by [20], [21], [22]).…”

Improving Species Diversity and Biomass Estimates of Tropical Dry Forests Using Airborne LiDAR

“…In other words, the inclusion of different habitat conditions at a larger scale (cluster of four plots over an area of 1.0 ha) may reveal a relationship between species richness and habitat heterogeneity that is not captured at the local, single-plot scale [56]. For example, the variety of land cover classes within clusters of four plots may be correlated with species richness, reflecting different topographic conditions and stages of forest succession, as also found by [27,57], respectively. Both studies were performed in tropical dry forests of the Yucatan Peninsula.…”