Worldwide, policies are increasingly aimed at planting more trees and crops both to combat climate change and increase food and fuel production. Already about 40 per cent of the world’s ice-free land surface has been converted to forestry and agriculture—often with only a few choice tree species and crops where biodiversity once thrived. This trend is poised to continue or even accelerate.
But in an article published in Nature GeoScience, the scientists argue that mixed-species diversity is crucial to the water cycle pathways that enable soil-plant-water systems to recover quickly from environmental stresses. Forestry and agricultural monocultures (growing a single species repeatedly on the same land) can constrain these pathways, adversely affecting conditions such as soil moisture and erosion, streamflow, evaporation, and groundwater quality—and ultimately reducing ecological resilience.
The authors urge policy makers and land managers to take into account critical water-vegetation interactions to guide decisions about what to plant and where.
“When we modify landscapes to help combat climate change or meet human demands for food and energy, we need to be smart about it,” said Irena Creed, a University of Saskatchewan hydrologist who co-led the think tank paper with University of Delaware researcher Delphis Levia.
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