Soil nutrients and dispersal limitation shape compositional variation in secondary tropical forests across multiple scales

Abstract

Soil resource partitioning and dispersal limitation have been shown to shape the tree community structure of mature tropical forests, but are poorly studied in the context of forest succession. We examined the relative contributions of both ecological processes to the variation in the species composition of young tropical secondary forests at different spatial scales, and if the relative importance of these two ecological processes changed during succession. At the species level, we examined if the association between species abundances and soil fertility differed between early and late successional species and/or changed over the course of succession. We used vegetation and soil data from 47 secondary forest sites with two plots each in a tropical agricultural landscape. A distance‐based redundancy analysis and variation partitioning were employed to examine the relative importance of spatial distance (proxy for dispersal limitation) and heterogeneity in soil nutrients (proxy for soil nutrient partitioning) at the landscape scale, and a linear regression to test their effects at the local scale. We examined interspecific variation in species’ responses to successional age and soil nutrients with a joint species distribution model. Dispersal limitation and soil niche partitioning drove considerable variation in the composition of plant communities at local and landscape scales. The relative contribution of these two ecological processes changed with scale (local vs. landscape) and topography (lower slope vs. upper slope plots). At the species level, significant abundance–soil fertility associations were mostly positive. Most species became less responsive to soil nutrients over the first few decades of tropical forest succession, probably because light became the main limiting resource in older forests. Synthesis. Our key finding is that spatial heterogeneity in soil resources and spatial distance jointly drive compositional variation within and across early successional forests. Our results highlight that a network of forest fragments enhances the resilience of ecological processes and the potential of secondary forests to restore and preserve biodiversity in human‐modified landscapes. To advance our understanding of ecological succession, we need to move beyond single‐factor and local‐scale studies and examine the effects of multiple variables on succession at different spatial scales.

Edaphic factors and initial conditions influence successional trajectories of early regenerating tropical dry forests

“…A similar relationship has been found on early successional forests, where topography affects nutrient concentrations (e.g. P and Mg), which then affect community composition between upslope plots versus downslope plots (van Breugel et al, ). Other aspects of young successional forests are affected by topography.…”

“…In old growth forests, soil nutrients have been found to determine species distributions (Hall, McKenna, Ashton, & Gregoire, ), to determine community structure at local scales (Baldeck et al, ), to affect growth of both saplings and trees (Turner, Brenes‐Arguedas, & Condit, ) and to determine the distribution of tree species at regional scales (Condit, Engelbrecht, Pino, Pérez, & Turner, ). In young secondary forests, soil fertility in terms of N and P can have significant effects on plant performance (Ayala‐Orozco et al, ; van Breugel et al, ; Lawrence, ; Powers & Marín‐Spiotta, ). For example, Werden et al () found that soil chemistry, including P, determined the distribution of 82 species across 84 successional dry forest plots in Costa Rica.…”

Natural recovery of plant species diversity in secondary forests in Eastern Amazonia: contributions to passive forest restoration

“…Another probable factor is the increased similarity in environmental factors such as soil, slope and precipitation (e.g. Aragón and Morales 2003;Chazdon 2013, van Breugel et al 2019. There are important differences between the studied municipalities which may also be responsible for the floristic separation found, including differences in altitude, soils and annual rainfall.…”

“…3 Non-metric multidimensional scaling (NMDS) using Bray-Curtis index of the floristic composition of the A) upper stratum (plants with DBH ≥ 10 cm) (stress = 11.57) and B) lower stratum (plants with DBH ≤ 10 cm) (stress = 13.56) among 20 fragments of secondary forests in the Southeast of Pará, Eastern Amazonia. The numbers in the NMDS ordination represent the age of each site increases in shade and improvements in soil conditions, favouring certain species and functional groups, such as shade-tolerant species (Do Valle et al 2018;Pinho et al 2018;van Breugel et al 2019).…”

Landform type mediates compositional change in a hurricane-disturbed sub-tropical forest

“…Whole-forest differences in the tree community over time were not significant, but there were significant differences in the tree community over time attributable to landform type, suggesting differences in succession between landform types. Successional change in forests is classically considered to be a function of soil depth and acute disturbance events (e.g., fire), but succession is a complex phenomenon operating at multiple scales in space-time (Breugel et al 2019) and can occur without a predictable trajectory (Chazdon et al 2007), which is how we consider succession here. Also, unlike successions initiated by fires or clearcutting that homogeneously reset the system to early stages, compositional change after a hurricane resets stands to earlier stages depending on the exposure of the landform to prevailing winds and the effects of winds on trees.…”