Climate-Induced Changes in Agroecosystems and Forest-Cropland Interactions in the Eastern Himalaya

Mountains are among the most sensitive systems to climate change due to their elevation gradients and unique ecological setup. The Himalaya is not an exception. However, in the eastern Himalaya, due to more complex terrain and remoteness, there is a gap in empirical research on how global climate change is affecting agro-ecosystems and their interactions with adjoining forests. Therefore, to bridge this gap, this research attempted to answer the following questions. How is global climate change altering local weather patterns? What is the effect of this alteration on crop composition, production, and the function of agro-ecosystems? Is there any change in forest-cropland interaction due to global climate change? Mann-Kendall test, Sen’s slope estimator, and Precipitation Concentration Index (PCI) were used to identify trends and seasonality in historical climatic datasets (1975-2025, ERA5). Scheduled-based surveys among farmers from 500 forest-adjoining croplands at different elevations (150-2000 m) were carried out to record the frequency of wild foraging, pest attack, disease, crop composition, and yield-based changes. Location of invasive species in the field was recorded to model the change in species distribution using a Random Forest (RF) algorithm. Findings revealed a statistically significant upward trend in temperature (0.8 – 1.9°C increase in mean temperature in 50 years), and a shift in intra-annual rainfall regime (wet season shifted from ‘June-August’ to ‘July-September’). Moreover, increased seasonal concentration of rain made the wet season wetter and the dry season drier. Consequently, farmers are forced to delay the sowing of rice. Similarly, pest attacks during the dry season and the spread of fungal diseases during the wet season have increased in response to the increased seasonality. Furthermore, the productivity of major crops (maize, rice, and oranges) and cash crops (large cardamom and ginger) has declined 57% and 80%, respectively, according to 83% respondents. Farmers are shifting toward wheat, chilli, and winter vegetables over traditional crop combinations due to reduced water and warming. Crops typical of lower elevations are increasingly being adopted in middle altitudes (900-1800m). RF modelling further revealed that invasive species (such as Lantana camara, Ageratina adenophora, Chromolaena odorata, and Conoclinium coelestinum) are expanding their habitats in and around forest and croplands of higher altitudes (>1800m). Collectively, all these changes, along with the reduced availability of pollinator species, resulted in a decrease in the availability of local shrubs and wild fruits, including Diplazium esculentum, Urtica parviflora, Rubus, Prunus, and Berberis berries. As a result, food scarcity is occurring in forests. Therefore, wild animals, including primates, bears, deer, peacocks, porcupines, wild boars, and foxes, increasingly foraged into forest-adjoining croplands as reported by 89.2% of the surveyed farmers in recent years. Together, these findings conclude that warming and redistribution of rain are reshaping cropping systems, forest food availability, and wildlife movement across elevation gradients. This highlights the urgent need for climate-resilient, sustainable agriculture and effective conservation strategies to mitigate global climate change in the Himalaya.