The suitability of Macadamia and Juglans for cultivation in Nepal: an assessment based on spatial probability modelling using climate scenarios and in situ data

Global climate models predict temperature rises and changes in precipitation regimes that will shift regional climate zones and influence the viability of agricultural crops in Nepal. Understanding the influence of climate change on local climates and the suitability of specific sites for the production of individual crop types at present and in the future is crucial to increasing local crop resilience and ensuring the long-term viability of plantations-especially of high-value, perennial tree crops that require significant investment. This paper focuses on two cash crops, Macadamia and Juglans. A literature review summarises data on temperature, precipitation, and other macro- and microclimatic requirements of both genera. On this basis, we investigate the short- and long-term suitability of areas in Nepal for production of the two crops by means of a spatial model based on extensive in situ measurements, meteorological data, and climatic layers from the WorldClim dataset. Finally, we track changes in potential cultivation area under four Representative Concentration Pathways. Results show that climatic requirements for the cultivation of Macadamia and Juglans are fulfilled across a large part of Nepal at present and in the future: the total suitable area for both trees shrinks only marginally under all four scenarios. However, suitable areas shift considerably in spatial and altitudinal terms, meaning that some currently productive areas will become unproductive in the future, while currently unproductive ones will become productive. We conclude that the consideration of macro- and microclimatic changes in agricultural planning is essential to long-term agricultural success in Nepal.