Figure 20.8 The effects of temperature and precipitation on the net primary productivity of terrestrial ecosystems. (a) Locations on Earth that have higher mean annual temperatures have higher NPP. (b) Locations that have higher mean annual precipitation have higher NPP but at locations with the highest amounts of precipitation, increased leaching and reduced decomposition of organic matter cause NPP to decline.

Data from E. A. G. Schuur, Productivity and global climate revisited: The sensitivity of tropical forest growth to precipitation, Ecology 84 (2003): 1165–1170.