From the University of California Riverside:
Grasslands across the globe, which support the majority of the world’s grazing animals, have been transitioning to shrublands in a process that scientists call “woody plant encroachment.”
Managed grazing of drylands is the most extensive form of land use on the planet, which has led to widespread efforts to reverse this trend and restore grass cover due to the belief that it results in less water entering streams and groundwater aquifers.
A new study led by Adam Schreiner-McGraw, a postdoctoral hydrology researcher at the University of California, Riverside, modeled shrub encroachment on a sloping landscape and reached a startling conclusion: Shrub encroachment on slopes can increase the amount of water that goes into groundwater storage. The effect of shrubs is so powerful that it even counterbalances the lower annual rainfall amounts expected during climate change.