Greening and Browning Trends on the Pacific Slope of Peru and Northern Chile

Accurate detection and quantification of regional vegetation trends are essential for understanding the dynamics of landscape ecology and vegetation distribution. We applied a comprehensive trend analysis to satellite data to describe geospatial changes in vegetation along the Pacific slope of Peru and northern Chile, from sea level to the continental divide, a region characterised by biologically unique and highly sensitive arid and semi-arid environments. Our statistical analyses show broad regional patterns of positive trends in EVI, called "greening", alongside patterns of "browning", where trends are negative between 2000 and 2020. The coastal plain and foothills, up 1000 m, contain notable greening of the coastal Lomas and newly irrigated agricultural lands occurring alongside browning trends related to changes in land use practices and urban development. Strikingly, the precordilleras show a distinct 'greening strip', which extends from approximately 6 & DEG;S to 22 & DEG;S, with an altitudinal trend, ascending from the tropical lowlands (170-780 m) in northern Peru to the subtropics (1000-2800 m) in central Peru and temperate zone (2600-4300 m) in southern Peru and northern Chile. We find that the geographical characteristics of the greening strip do not match climate zones previously established by Koppen and Geiger. Greening and browning trends in the coastal deserts and the high Andes lie within well defined climatic and life zones, producing variable but identifiable trends. However, the distinct Pacific slope greening presents an unexpected distribution with respect to the regional Koppen-Geiger climate and life zones. This work provides insights on understanding the effects of climate change on Peru's diverse ecosystems in highly sensitive, biologically unique arid and semi-arid environments on the Pacific slope.