Abstract

Water scarcity contributes to the poverty of around one-third of the world's people. Despite many benefits, tree planting in dry regions is often discouraged by concerns that trees reduce water availability. Yet relevant studies from the tropics are scarce, and the impacts of intermediate tree cover remain unexplored. We developed and tested an optimum tree cover theory in which groundwater recharge is maximized at an intermediate tree density. Below this optimal tree density the benefits from any additional trees on water percolation exceed their extra water use, leading to increased groundwater recharge, while above the optimum the opposite occurs. Our results, based on groundwater budgets calibrated with measurements of drainage and transpiration in a cultivated woodland in West Africa, demonstrate that groundwater recharge was maximised at intermediate tree densities. In contrast to the prevailing view, we therefore find that moderate tree cover can increase groundwater recharge, and that tree planting and various tree management options can improve groundwater resources. We evaluate the necessary conditions for these results to hold and suggest that they are likely to be common in the seasonally dry tropics, offering potential for widespread tree establishment and increased benefits for hundreds of millions of people.

Published in

Scientific Reports
2016, Volume: 6, article number: 21930
Publisher: NATURE PUBLISHING GROUP

SLU Authors

• Ilstedt, Ulrik

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Bargues Tobella, Aida

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Nyberg, Gert

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Benegas, Laura

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Laudon, Hjalmar

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Malmer, Anders

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Ensure availability and sustainable management of water and sanitation for all
Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss
End poverty in all its forms everywhere


UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1038/srep21930

Permanent link to this page (URI)

https://res.slu.se/id/publ/71840