Abstract

Tropical regions are likely to experience more intense rainfall events in the future. Such an increase in rainfall intensities will affect soil and groundwater recharge, with potential consequences for millions of people. However, little is known about the impact of tree cover on soil and groundwater recharge under higher rainfall intensities. Here, we investigated the effect of tree cover and rainfall intensity on soil water drainage in an agroforestry parkland in West Africa. We collected soil water drainage from lysimeters located at 50 and 150 cm depth in both small and large open areas among trees, which represent contrasting degrees of tree cover, and analyzed a subset of water samples for delta O-18 and delta H-2 to gain insights into the mechanisms of water flow within the soil profile. We found that under high rainfall intensities (>20 mm d(-1)), the median daily soil water drainage amount at 150 cm was 13 times higher in the small compared with the large open areas, whereas at 50 cm, there were no significant differences. Low rainfall intensities (<10 mm d(-1)) resulted in little soil water drainage both at 50 and 150 cm depth, regardless of canopy opening size. The isotopic signature of soil water drainage suggested less evaporation and a higher degree of preferential flow in small compared with large open areas. Our results suggest that maintaining or promoting an appropriate tree cover in tropical African drylands may be key to improving deep soil and groundwater recharge under a future climate with more heavy rainfall.

Keywords

drylands; groundwater recharge; intense rainfall; macropores; tree cover; water stable isotopes

Published in

Land Degradation and Development
2020, Volume: 31, number: 1, pages: 81-95

SLU Authors

• Bargues Tobella, Aida

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • World Agroforestry Centre (ICRAF)

• Hasselquist, Niles

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

• Laudon, Hjalmar

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

• Ilstedt, Ulrik

  • 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
Take urgent action to combat climate change and its impacts


UKÄ Subject classification

Ecology
Soil Science


Publication identifier

DOI: https://doi.org/10.1002/ldr.3430

Permanent link to this page (URI)

https://res.slu.se/id/publ/102527