Water abstraction of invasive Prosopis juliflora and native Senegalia senegal trees: A comparative study in the Great Rift Valley Area, Ethiopia

Hailu Shiferaw; Tena Alamirew; Sebinasi Dzikiti; Woldeamlak Bewket; Gete Zeleke; Demel Teketay; Urs Schaffner

doi:10.1016/j.scitotenv.2022.160833

Water abstraction of invasive Prosopis juliflora and native Senegalia senegal trees: A comparative study in the Great Rift Valley Area, Ethiopia

Sci Total Environ. 2023 Mar 1:862:160833. doi: 10.1016/j.scitotenv.2022.160833. Epub 2022 Dec 9.

Authors

Hailu Shiferaw¹, Tena Alamirew², Sebinasi Dzikiti³, Woldeamlak Bewket⁴, Gete Zeleke², Demel Teketay⁵, Urs Schaffner⁶

Affiliations

¹ Water and Land Resource Centre, Addis Ababa University, P.O. Box 3880, Addis Ababa, Ethiopia. Electronic address: Hailu.s@wlrc-eth.org.
² Water and Land Resource Centre, Addis Ababa University, P.O. Box 3880, Addis Ababa, Ethiopia.
³ Department of Horticultural Science, Stellenbosch University, P Bag X1 Matieland, Stellenbosch 7602, South Africa.
⁴ Department of Geography and Environmental Studies, Addis Ababa University, P.O. Box 1176, Ethiopia.
⁵ Botswana University of Agriculture and Natural Resources, Department of Range and Forest Resources, Private Bag 0027, Gaborone, Botswana.
⁶ CABI, Rue des Grillons 1, CH-2800 Delémont, Switzerland.

PMID: 36509281
DOI: 10.1016/j.scitotenv.2022.160833

Abstract

Besides direct water abstraction, natural water scarcity in semi-arid and arid regions may be further exacerbated by human-assisted changes in vegetation composition, including the invasion by non-native plant species. Water abstraction by the invasive tree Prosopis juliflora and by the native Senegalia senegal was compared in the dry Great Rift Valley, Ethiopia. Transpiration rates were quantified using the heat ratio method on six trees each of P. julifora and S. senegal, growing adjacent to each other in the same environment. Water use for P. juliflora trees ranges from 1 to 26 L/day (an average of 4.74 ± 1.97), and that of S. senegal trees from 1 to 38 L/day (an average of 5.48 ± 5.29 during two study years). For both species, soil heat, latent heat, and soil moisture status influenced the rates of sap flow of trees; in addition, water use by P. juliflora trees was related to vapor pressure deficit; the higher the vapor pressure deficit, the higher the water abstraction by P. juliflora. Stand densities of pure P. juliflora and S. senegal were 1200-1600 trees and 400-600 trees per ha, respectively. At the stand scale, P. juliflora consumed approximately 6636 L/day/ha (transpiration: 242 mm per year) and S. senegal stands consumed 2723 L/day/ha (transpiration: 87 mm per year). That is, P. juliflora stands consumed three times more water than S. senegal stands, because of two reasons: (1) P. juliflora stands are denser than S. senegal stands, and denser stands consume more water than less dense stands, and (2) P. juliflora is evergreen and uses water all year-round, while S. senegal sheds its leaves during the peak dry seasons. Our findings suggest that, compared to S. senegal, P. juliflora invasion results in severe impacts on groundwater resources of the drylands of Ethiopia, with direct and indirect consequences to ecosystem services and rural livelihoods.

Keywords: Dryland; Invasive species; Sap flow; Transpiration; Tropical region; Water use.

MeSH terms

Ecosystem
Ethiopia
Humans
Plant Transpiration
Prosopis*
Senegal
Soil
Trees*
Water

Substances

Water
Soil