Edaphic factors, successional status and functional traits drive habitat associations of trees in naturally regenerating tropical dry forests

Abstract

Many studies have examined individual environmental drivers of tropical tree species distributions, but edaphic and successional gradients have not been considered simultaneously. Furthermore, determining how functional traits influence species distributions along these gradients may help to elucidate mechanisms behind community assembly. To assess the influence of environmental filtering on tropical dry forest (TDF) tree species distributions, we used forest inventory data from sites with large edaphic and successional gradients in NW Costa Rica. Our goals were to determine (1) whether edaphic or successional factors are more important determinants of the abundance of individual tree species in regenerating TDF, (2) how species‐level functional traits are related to edaphic and/or successional niche associations of tree species and (3) correlations between species‐level edaphic and successional niche associations. The distributions of 82 focal tree species were strongly driven by both edaphic and successional gradients. Overall, 94% of species responded to soil chemistry, 89% to soil texture and 94% to stand age gradients. Some functional traits were correlated with the edaphic and successional niche associations of TDF tree species. Species that specialized on soils with high total nutrient concentrations had higher foliar nutrient concentrations (nitrogen and phosphorus) and lower leaf dry matter content (LDMC). Species with wider stand age niches had lower LDMC and wood density. There were no correlations between edaphic and successional niche optima of TDF tree species. Our results indicate that successional and edaphic gradients concurrently drive community assembly in regenerating TDF. Moreover, our work underscores the importance of considering how the functional characteristics of TDF trees dictate species distributions across environmental gradients. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13206/suppinfo is available for this article.

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

“…One reason is that nutrient strategies vary widely among tropical plant species, but are only studied for a small proportion of diverse tropical plant communities (van Breugel et al, ; Dalling, Heineman, Lopez, Wright, & Turner, ; Nasto et al, ), and usually not concurrently with species successional strategies (but see Craven, Hall, Berlyn, Ashton, & Breugel, ). This is only the second study that quantitatively assessed how soil nutrients and successional age simultaneously affect the abundance of plant species across secondary forests in a tropical landscape (Werden et al, ). Our data can be used to select species with contrasting successional and soil resource associations for more detailed explorations of their nutrient strategies and associated traits and experimental studies on the mechanisms governing soil resource partitioning (Batterman et al, ; Palmiotto et al, ).…”

“…However, both have been poorly studied in the context of forest succession (Arroyo‐Rodríguez et al, ; Kraft & Ackerly, ; Leibold et al, ; Meiners, Cadotte, Fridley, Pickett, & Walker, ). Here, we presented, to our knowledge, the first quantitative assessment of the relative contributions of these two ecological processes to the variation in the species composition of tropical secondary forests at different spatial scales (but see Jakovac et al, ; Lawrence, ; Werden et al, ). Our results corroborate evidence from other plant communities (Myers & Harms, ), including temperate successional forests (Verheyen & Hermy, ) that the successional niche, dispersal limitation and local edaphic heterogeneity concurrently structure early successional plant communities.…”

“…In contrast, surprisingly few studies have examined the effects of soil resource heterogeneity on the assembly of plant communities during secondary forest succession and results vary markedly. In a dry tropical region in Costa Rica, the distribution of the vast majority of the studied tree species was associated with soil chemistry (Werden, Becknell, & Powers, ), while results of a study on tree species‐soil associations in west Kalimantan, Indonesia, were more equivocal (Lawrence, Suma, & Mogea, ). A complicating factor in the latter study was that soil variables, land‐use history and landscape context were strongly correlated (Lawrence, ).…”

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

“…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. Likewise, Davidson et al () showed that experimental addition of N significantly increased tree biomass in a young successional moist forests in Brazil.…”

“…Lu, Moran, and Mausel () showed that higher available N concentrations on Alfisols positively affected forest biomass accumulation in early successional forests in Brazil, but that this effect was not present on Oxisols and Ultisols. In successional dry forests in Costa Rica, variation in soil chemistry and texture explained a substantial portion of species’ occurrences and distribution (Powers, Becknell, Irving, & Pèrez‐Aviles, ; Werden, Becknell, & Powers, ), but the relationship between soil properties and above‐ground biomass was weak (Becknell & Powers, ). At a regional scale, above‐ground biomass of secondary forests across the Neotropics does not seem to be related to soil cation exchange capacity (Poorter et al, ).…”