Impacts of land-use change on bush frogs, forest-dwelling lizards and arboreal snakes

Open ecosystems are more threatened than wet tropical rainforests. Unfortunately, these ecosystems are classified as wastelands and receive scant public attention. The low-elevation lateritic plateaus are geologically unique open ecosystems in the northern Western Ghats that harbour tremendous endemic diversity. Numerous petroglyphs on these plateaus, which are several thousand years old, depict a long-standing relationship between humans and the landscape. 

Animals living on these plateaus experience extreme weather conditions, from extremely dry and hot summers, to extremely wet conditions during the monsoon. Given the vast expanse of the lateritic plateaus in the northern Western Ghats, traditionally, locals have been growing rice paddy in depressions that harbour soil or by dumping soil on the lateritic plateaus and preventing its runoff by lining with loose rocks that are collected from the plateaus. More recently, locals have been blasting the plateau and planting mango and cashews in the soil-filled pits, making these ‘barren’ landscapes favourable for agroforestry. The mangoes grown in the low-elevation lateritic plateaus of Ratnagiri are supposed to be very sweet and fetch high prices. The accelerated growth of agroforestry plantations on the lateritic plateaus poses a significant risk to the persistence of these ecosystems. There are ongoing efforts to identify critical sites and protect them with the support of local communities by declaring them as bio-cultural heritage sites. One of the gaps for this was determining how conversion to other land uses is impacting biodiversity on these lateritic plateaus. We conducted three studies to determine the impacts of land-use change on rock-dwelling fauna and the role of microhabitats like loose rocks and rock pools in maintaining biodiversity on the plateau. We found that conversion to paddy and orchards negatively impacts the availability of large rocks, which provide refuge to animals like saw-scaled vipers and point-endemic white-striped viper geckos. Conversion to paddy and subsequent land abandonment increased soil and water availability, benefiting the fossorial and endemic Seshachari’s caecilian. We found that large rock pools provide critical microhabitats for breeding frogs and tadpoles, thereby maintaining frog diversity on lateritic plateaus. However, the availability of these rock pools drops in orchards. In paddy, the entire habitat is homogenised by submergence under water, with negative consequences for frogs. Along with other studies, we highlight the value of critical microhabitats like loose rocks and rock pools for sustaining biodiversity. This is among the first studies to determine land-use change’s impacts on lateritic plateaus’ biodiversity.