The resilience of Indian Western Himalayan forests to regime shift: Are they reaching towards no return point?

Abstract

Forests across the latitudes are facing regime shift under the influence of changing climate where temperature and precipitation are recognized as prominent drivers. Regime shift of forests can be in the form of conversion of one forest type into another or the alteration of forests into degraded class such as “scrub”. The Indian Western Himalayan (IWH) region hosts valuable forests to support multiple ecosystem services which may be impacted under different thresholds of regime shift. We assessed the threshold of regime shift as transition of forests into scrub considering temperature and precipitation records of the recent decade (2000–2019). A logistic regression model was developed using the forest cover data of IWH as a dependent variable and climatic records (temperature and precipitation) obtained from ERA-5 data as independent variables. Probability values of two classes (forest and scrub) were computed and were used to define present resilience states. The majority of the forest of the IWH region may not withstand any significant rise in temperature or a reduced amount of precipitation as almost 88.68% of forests of the IWH are under the low to moderate resilience category. Forest resilience significantly decreases below 1500 mm of precipitation indicating its tipping point of regime shift into the scrub. Temperature below 6 °C is not favourable for forests whereas a temperature range of 10–20 °C was found as the conducive range for the existence of forests in the region. Such empirical study would support the formulation of management plans and policies for sustainable forest resources and to assess the impacts of climate change.