Secondary forest succession buffers extreme temperature impacts on subtropical Asian ants

Abstract

Secondary forest succession may restore microclimatic refugia for ectotherms and play a fundamental role in mitigating the combined effects of deforestation and climate warming on biodiversity; however, empirical evidence remains limited by short-term, coarsescale, and solely taxonomic-based approaches. We hypothesize that ant assemblage composition will respond differently to an increased frequency of extreme heat events between sites with and without microclimatic refugia provided by secondary forest's regrowth. We test this hypothesis by integrating comprehensive historic surveys (1992)(1993)(1994) and contemporary resampling (2015-2017) of ant assemblages to investigate how soil surface temperatures (estimated by microclimatic models [30 × 30 m]) and physical parameters (e.g., canopy cover) over the past >20 yr drive changes in their taxonomic, functional, and phylogenetic diversity for open (grasslands and shrublands) and closed (secondary forests) habitat types. Our results show a significant spatial turnover in the ant assemblage composition in both habitat types over the past two decades. Furthermore, for taxonomic, functional and phylogenetic spatial beta diversity, temperature became the primary variable explaining the differences in species composition among sites in open habitats, but not in closed habitats. Nevertheless, leaf litter cover may, to a certain extent, provide some thermal buffer for litter-dwelling species exposed to extreme heat. On the contrary, within forests, canopy cover mitigated the adverse impact of extreme heat on ant assemblages, with a shift toward smaller body size observed over time only in sites with lower canopy cover. These findings highlight the importance of restored canopy in providing thermal buffering for understory ectotherms. While tropical forest restoration represents an essential component in enhancing species resilience under climate warming, additionally we considered that the restoration of microclimatic regimes across different land use types is essential to conserve tropical biodiversity across the deforested landscape.

Ant body size mediates functional performance and species interactions in carrion decomposer communities

“…Indeed, most baiting experiments performed on ants for the purpose of comparative studies have used baits placed on plastic (Griffiths et al., 2018; Sheard et al., 2020) to make it more conspicuous and to count individuals present. Additionally, our experiment was conducted within forest habitats in which temperature differences are buffered by canopy cover (Lee et al., 2021) and during the wet season in which both temperature (>27°C) and humidity levels remain high (>94%) during the course of our experiment. Also, some of the field experimental sites were close to each other (±30 m).…”

“…Indeed, most baiting experiments performed on ants for the purpose of comparative studies have used baits placed on plastic (Griffiths et al, 2018;Sheard et al, 2020) to make it more conspicuous and to count individuals present. Additionally, our experiment was conducted within forest habitats in which temperature differences are buffered by canopy cover (Lee et al, 2021)…”

Diversity begets diversity: Low resource heterogeneity reduces the diversity of nut‐nesting ants in rubber plantations

“…Structural heterogeneity refers to variation in the physical structure of the environment in a given habitat (Stevens & Tello, 2011). High canopy cover and leaf litter cover in forest can provide more diverse microhabitats for ants and thus can indicate structural heterogeneity (Lee et al ., 2021). We measured the canopy coverage of each sampling site by averaging the canopy cover obtained from five 1 m 2 quadrats within a 20 m × 20 m quadrat (four at the corner and one in the center) using a convex (model A) spherical crown densitometer.…”

Forest regeneration pathways in contrasting deforestation patterns of Amazonia

“…Secondary vegetation has an increasing role in landscape planning and management to face current climate and biodiversity crises, offsetting some of the most pervasive consequences of deforestation. Secondary vegetation is currently recognized as an important sink of carbon dioxide (Jones et al, 2019;Hall et al, 2022), a regulator of local climate (Lee et al, 2021;van Meerveld et al, 2021), and a water systems stabilizer (van Meerveld et al, 2021). It also has an important role in biodiversity conservation, since secondary vegetation recovers part of the taxonomic and functional diversity and habitat structure (Poorter et al, 2021).…”