Abstract. Vegetation provides key ecosystem services and is an important component in the hydrological
cycle. Traditionally, the global distribution of vegetation is explained through climatic water
availability. Locally, however, groundwater can aid growth by providing an extra water source
(e.g. oases) or hinder growth by presenting a barrier to root expansion (e.g. swamps). In this
study we analyse the global correlation between humidity (expressing climate-driven water and energy availability), groundwater and forest growth, approximated by the fraction of absorbed
photosynthetically active radiation, and link this to climate and landscape position. The results
show that at the continental scale, climate is the main driver of forest productivity; climates
with higher water availability support higher energy absorption and consequentially more
growth. Within all climate zones, however, landscape position substantially alters the growth
patterns, both positively and negatively. The influence of the landscape on vegetation growth
varies over climate, displaying the importance of analysing vegetation growth in a
climate–landscape continuum.
Supplementary material to "Global distribution of hydrologic controls on forest growth"
