title: The effect of trees on preferential flow and soil infiltrability in an agroforestry parkland in semiarid Burkina Faso.
abstract: Water scarcity constrains the livelihoods of millions of people in tropical drylands. Tree planting in these environments is generally discouraged due to the large water consumption by trees, but this view may neglect their potential positive impacts on water availability. The effect of trees on soil hydraulic properties linked to groundwater recharge is poorly understood. In this study, we performed 18 rainfall simulations and tracer experiments in an agroforestry parkland in Burkina Faso to investigate the effect of trees and associated termite mounds on soil infiltrability and preferential flow. The sampling points were distributed in transects each consisting of three positions: (i) under a single tree, (ii) in the middle of an open area, and (iii) under a tree associated with a termite mound. The degree of preferential flow was quantified through parameters based on the dye infiltration patterns, which were analyzed using image analysis of photographs. Our results show that the degree of preferential flow was highest under trees associated with termite mounds, intermediate under single trees, and minimal in the open areas. Tree density also had an influence on the degree of preferential flow, with small open areas having more preferential flow than large ones. Soil infiltrability was higher under single trees than in the open areas or under trees associated with a termite mound. The findings from this study demonstrate that trees have a positive impact on soil hydraulic properties influencing groundwater recharge, and thus such effects must be considered when evaluating the impact of trees on water resources in drylands.
  
  
  CONCLUSIONS
  Trees in dryland landscapes increase soil infiltrability and preferential flow Termite mounds in association with trees further enhance preferential flow.
authors: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU) Umeå, Sweden.
authors: A
authors: A
authors: Bargués Tobella
authors: Department of Forest Resource Management, Swedish University of Agricultural Sciences (SLU) Umeå, Sweden.
authors: H
authors: H
authors: Reese
authors: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU) Umeå, Sweden.
authors: A
authors: A
authors: Almaw
authors: World Agroforestry Centre (ICRAF), West and Central Africa Regional Office Bamako, Mali.
authors: J
authors: J
authors: Bayala
authors: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU) Umeå, Sweden.
authors: A
authors: A
authors: Malmer
authors: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU) Umeå, Sweden.
authors: H
authors: H
authors: Laudon
authors: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU) Umeå, Sweden.
authors: U
authors: U
authors: Ilstedt
keywords: Brilliant Blue FCF; agroforestry parklands; dry lands; infiltration; open woodlands; preferential flow; rainfall simulations; semiarid tropics; termites; trees
references: Nat Resour Forum. 1989 Nov;13(4):258-67
references: 12317608
references: Science. 2005 Dec 23;310(5756):1944-7
references: 16373572
references: Science. 1990 Mar 2;247(4946):1043-8
references: 17800060
references: Ecology. 2008 Jun;89(6):1521-31
references: 18589517
references: Ecology. 2010 May;91(5):1296-307
references: 20503863
references: J Biogeogr. 2013 Jun;40(6):1036-1047
references: 23935237
references: Oecologia. 1986 Mar;68(4):521-528
references: 28311707