Using statistical models to depict the response of multi-time scales drought to forest cover change across climate zones

Abstract. The interaction between forest and climate exhibits regional differences due to a variety of biophysical mechanisms. Observational and modelling studies have investigated the impacts of forested and non-forested areas on a single climate variable, but the influences of forest cover change on a combination of temperature and precipitation (e.g., drought) have not been explored owing to the complex relationship between drought conditions and forests. In this study, we use the historical forest and climate datasets to explore the changes in forest fraction and drought from 1992–2018. A set of linear models and an analysis of variance approach are utilized to investigate the effect of various factors on droughts across different time scales and climate zones. Our findings reveal that precipitation is the dominant factor leading to drought in the equatorial, temperate, and snow regions, while temperature controls drought in the arid region. The impact of forest cover on droughts varies under different precipitation and temperature quantiles. Precipitation modulates forest cover's impact on long-term drought in arid and snow regions, while temperature modulates forest cover's impact on both short- and long-term drought in the arid region as well as only on long-term drought in temperate and snow regions. Forest cover can also modulate the impacts of precipitation and temperature on drought. High forest cover leads to a combined effect of precipitation and temperature on long-term drought in equatorial, arid and snow regions, while precipitation is the only dominant factor in low forest cover conditions. In contrast, low forest cover triggers a strong combined effect of precipitation and temperature on drought in the temperate region. Our findings improve the understanding of the interaction between land cover change and the climate system and further assist decision-makers to modulate land management strategies in different regions in light of climate change mitigation and adaptation.