Species sorting and mass effect along forest succession: Evidence from taxonomic, functional, and phylogenetic diversity of amphibian communities

Abstract

Species recovery after forest disturbance is a highly studied topic in the tropics, but considerable debate remains on the role of secondary forests as biodiversity repositories, especially regarding the functional and phylogenetic dimensions of biodiversity. Also, studies generally overlook how alpha and beta diversities interact to produce gamma diversity along successional gradients. We used a metacommunity approach to assess how species sorting (i.e., environmental filtering) and mass effect (i.e., source‐sink dynamics) affect 14 complementary metrics of amphibian taxonomic, functional, and phylogenetic diversity along a successional gradient in southern Mexico. As amphibians have narrow environmental tolerances and low dispersal capabilities, we expected that species sorting may be relatively more important than mass effect in structuring amphibian communities. Between 2010 and 2012, we sampled frogs, salamanders, and caecilians in 23 communities distributed in four successional stages: young (2–5 years old) and intermediate (13–28 years old) secondary forests, old‐growth forest fragments, and old‐growth continuous forest. We assessed 15 ecologically relevant functional traits per species and used a time‐calibrated molecular phylogeny. We recorded 1,672 individuals belonging to 30 species and 11 families. Supporting our expectations from the species sorting perspective, from the poorest (younger forests) to the best quality (continuous forest) scenarios, we observed (a) an increase in alpha diversity regardless of species abundances; (b) a clear taxonomic segregation across successional stages; (c) an increase in functional richness and dispersion; (d) an increase in mean phylogenetic distance and nearest taxon index; and (e) a reduction in mean nearest taxon distance. However, 10 species occurred in all successional stages, resulting in relatively low beta diversity. This supports a mass effect, where interpatch migrations contribute to prevent local extinctions and increase compositional similarity at the regional scale. Our findings indicate that amphibian metacommunities along forest successional gradients are mainly structured by species sorting, but mass effects may also play a role if high levels of forest cover are conserved in the region. In fact, secondary forests and forest fragments can potentially safeguard different aspects of amphibian diversity, but their long‐term conservation value requires preventing additional deforestation.

Sparing land for secondary forest regeneration protects more tropical biodiversity than land sharing in cattle farming landscapes

“…Our study underscores the importance of long-term protection of spared secondary forests for delivering biodiversity gains (see also [35], [55]), in addition to other ecosystems services, such as carbon stocking [26], [56], [57], [44] and preventing landslides or soil erosion [58]. However, regenerating forests tend to be poorly protected, with laws, policies and socioeconomic conditions that can work against long-term persistence.…”

Respuestas de la diversidad taxonómica y funcional a la transformación del paisaje: relación de los ensamblajes de anfibios con cambios en el uso y cobertura del suelo

“…De manera complementaria, el análisis de grupos funcionales reflejó otras características no contempladas por las métricas de riqueza (funcional y de especies), resaltando el valor de conservación para los cultivos de caña y cacao, principalmente para las especies pertenecientes a los grupos funcionales I, II y III. En ese sentido, es necesario ampliar las métricas para el análisis de los ensamblajes, considerando no solo las facetas taxonómica y funcional de la diversidad, sino, involucrando la diversidad filogenética para entender como los factores ambientales generan filtros en hábitats transformados moldeando y estructurando a los ensamblajes de anfibios (Hernández-Ordóñez et al, 2019;Ribeiro et al, 2017).…”

“…Así mismo, los rasgos ecológicos como los modos reproductivos y el hábito de las especies son aspectos importantes para entender la sensibilidad de las especies ante la degradación del hábitat (Cortés-Gómez et al, 2016). En ese sentido, las especies que presentan desarrollo directo o huevos depositados en hojas sobre quebradas son más sensibles a la transformación del hábitat (Mendenhall et al, 2014), lo que se ve reflejado en que los ensamblajes en bosques maduros y conservados presenten mayor riqueza y dispersión funcional debido a un incremento en los modos reproductivos y a la amplitud en el valor de otros rasgos funcionales (Hernández-Ordóñez et al, 2019). Sin embargo, las especies que requieren cuerpos de agua para la ovoposición también pueden ser afectadas por la fragmentación o aislamiento del hábitat debido a que realizan migraciones entre ambientes de bosque nativo y los cuerpos de agua (Becker et al, 2010).…”

Responses of anuran diversity to wetland characteristics and surrounding landscape in the Southern Andean Yungas, Argentina

“…The absence of a strong relationship between species diversity and the surrounding habitat matrix may be explained by the fact that most recorded species are generalists and relatively resistant to moderate human disturbance (Pereyra et al, 2018). Also, the maintenance of local amphibian diversity in the breeding ponds could be due to mass effect (source–sink dynamics) of individuals that migrate from patches of secondary forest in the complex matrix of the study area (Hernández‐Ordóñez et al, 2019).…”