Orchards and paddy differentially impact rock outcrop amphibians: Insights from community- and species-level responses

Abstract

With agricultural demands increasing globally, determining the nature of impacts of different forms of agriculture on biodiversity, especially for threatened vertebrates and habitats, is critical to inform land management. We determined the impacts of converting rock outcrops (a habitat more threatened than rainforests) to orchards and paddy on anurans in the Western Ghats biodiversity hotspot. We sampled 50 belt transects four times across four sites during the rainy season and recorded information on amphibians and their microhabitats. We determined community-level responses using Hill numbers, beta-diversity measures, and non-metric multidimensional scaling, and species-level responses using joint species distribution modelling. Converting rock outcrops to paddy and orchards significantly altered microhabitat availability. Conversion to paddy mostly had community-level impacts, i.e., lowered species richness and more nested communities, whereas conversion to orchards mostly had species-level impacts, i.e., lowered species occurrence, highlighting the differential impacts of different forms of agriculture on amphibians and the need to determine impacts of land-use change on communities and species concurrently. We show that large rock pools are critical microhabitats for anurans as they serve as a refuge and protect anurans from desiccation during dry spells, which may be prolonged by climate change. Since rock outcrop habitats in low elevations are rapidly being converted to orchards, efforts are needed to conserve them in partnership with local communities, the custodians of these habitats. Our findings demonstrate that different forms of agriculture can have divergent impacts on biodiversity, and determining their impacts may require assessments at multiple scales, from species to communities.HIGHLIGHTSOrchard and paddy conversions affect anurans and their microhabitats on rock outcropsConversion to paddy has community-level impacts, i.e., reduced diversityConversion to orchards has species-level impacts, i.e., lowered species occurrenceRock pools, an important habitat for outcrop anurans, must be preserved or createdThere is a need to study species-and community-level impacts simultaneously

Effects of abiotic and biotic drivers on tadpoles in seasonal rock pools of Western Ghats rock outcrops, India

“…End of monsoon would increase the risk of desiccation for the growing tadpoles. Incidentally, we found lower incidences of Microhyla and Polypedates adults towards the end of monsoon (Jithin et al, 2023). This indicates lowered breeding intensity towards the end of monsoon, which may also contribute to lower tadpole occurrence and abundance.…”

“…Given the differing responses of tadpoles to different predictors, as revealed by the variance partitioning analysis, our results also highlight the importance of species-specific tadpole ecology studies, which can inform species-specific conservation strategies. Considering the global threats amphibians are facing from habitat degradation and land conversion, and particularly agricultural land-use change in the rock outcrops (Luedtke et al, 2023; Jithin et al, 2023), conservation strategies need to be developed based on both adult and tadpole ecology in the local context. Our study provides the first insights for rock pool restoration in the northern Western Ghats rock outcrops, based on tadpole ecology, complementing the previous work on adult frogs.…”

“…There is existing information on arthropod and aquatic plant communities (Sheth et al, 2019;Kulkarni et al, 2022;Kulkarni et al, 2023), but vertebrate ecology, especially of tadpoles, is lacking. Jithin et al (2023) showed that large FRPs are important for adults of three species of frogs: Euphlyctis jaladhara, Microhyla nilphamariensis, and Polypedates maculatus; and recommended restoration or creation of rock pools for amphibian conservation in light of reduced FRP availability because of rapid conversion of outcrops to orchards that reduces the availability of FRPs. Knowledge of tadpole ecology in the FRPs is essential for further research and conservation actions.…”