Climate woe: Thorny vegetation overruns evergreen Ghat forests

Chennai: Rising temperatures, erratic rainfall patterns and elevation-linked microclimates are steadily reshaping forest habitats across the Eastern and Western Ghats in Tamil Nadu, according to a recent study published in ‘Nature'. The research finds that climate-driven stressors are pushing evergreen and deciduous forests toward thorn-dominated vegetation, signalling a major ecological shift, as opposed to a simple decline in tree cover. The study covered a three-year period from 2021.Professor Emeritus at the centre for climate change and disaster management, Anna University, and lead author, A Ramachandran said the transformation was evident across large tracts of the hill ranges.
In Western Ghats alone, about 249sqkm of evergreen forest and 720sqkm of deciduous forest have been lost during the study period. At the same time, thorny forest cover expanded by nearly 969sqkm, underscoring what he described as a "systemic reorganisation" of forest types under sustained climatic pressure. Eastern Ghats show a comparable pattern, here 54sqkm evergreen forests and 716sqkm of deciduous forests have been replaced by thorny forests. The study says multiple stressors are acting simultaneously. Heat stress and altered rainfall are reducing biodiversity, disrupting carbon storage and cycling, and increasing vulnerability to invasive species and wildfires. These processes weaken moist and deciduous forest systems, allowing hardier thorny vegetation to take over.Ramachandran said declining regeneration of broad-leaf species was enabling thorny plants to intrude into both evergreen and deciduous forests. If thorn forests replace richer vegetation at mid and higher elevations, mega herbivores such as elephants may struggle to find adequate forage. The reduction of riparian forests could limit the growth of fruit-bearing trees, forcing frugivorous birds to seek alternative feeding, breeding and roosting sites. Drying of high-altitude wetlands may also push small mammals to search for new water sources, the study pointed out.Despite the grim trends, the researchers outlined measures that could slow or even reverse the changes. They called for removing invasive species, strengthening fire management, conserving soil and water through contour walls, check dams and percolation ponds, and promoting multi-layered afforestation with native trees.