Global Ecology and Conservation (Oct 2023)
Between a rock and a hard place: Comparing rock-dwelling animal prevalence across abandoned paddy, orchards, and rock outcrops in a biodiversity hotspot
Abstract
Rock outcrops are geologically and ecologically unique ecosystems that harbour threatened and endemic biodiversity. These underappreciated, open ecosystems are undergoing rapid land-use changes and the impacts of these changes on the threatened and endemic biodiversity are poorly understood, compared to the forested ecosystems. The unprotected, low-elevation lateritic plateaus of the northern Western Ghats of India are a case in point; they have high levels of endemism but are experiencing agricultural land-use change to orchards on the one hand and abandonment of traditional paddy cultivation on the other. We compared 1) the availability of loose rocks, a critical microhabitat for saxicolous animals, 2) the prevalence of an endemic caecilian (Gegeneophis seschachari), an endemic gecko (Hemidactylus albofasciatus), and a widespread snake (Echis carinatus), and 3) the composition and abundance of other rock-dwelling animals across 12 less-disturbed natural rock outcrop sites and 10 sites each in agroforestry plantations and abandoned paddies using time-constrained searches. By surveying 7179 surface rocks, we encountered 5738 individuals from 38 animal taxa. We found that the abundance of large rocks, which were the most-preferred size class of rocks by animals, was higher in abandoned paddy compared to plateaus and orchards. However, the prevalence of the reptiles H. albofasciatus and E. carinatus was highest on undisturbed plateaus. Contrastingly, the prevalence of G. seshachari, a caecilian, was significantly higher under rocks in abandoned paddy than in less-disturbed plateau or orchards. We also found significant differences between the rock-dwelling faunal assemblages across the three agricultural land-use types. Despite being adapted to persist in extremely variable climates on lateritic plateaus, multiple species/groups are vulnerable to land-use changes. However, G. seshachari and a few other taxa appear to benefit from certain kinds of agricultural land-use change, highlighting the context-specificity in species responses. This is one of the first studies to determine the impacts of the agricultural conversion of rock outcrops, thereby highlighting the conservation value of habitats that are often classified as wastelands.
