Differences in transpiration between a forest and an agroforestry tree species in the Sudanian belt

• Published in: Agroforestry systems Vol. 91; no. 3; pp. 403 - 413
• Main Authors: Awessou, Kohomlan G. Beranger, Peugeot, Christophe, Rocheteau, Alain, Seguis, Luc, Do, Frédéric C., Galle, Sylvie, Bellanger, Marie, Agbossou, Euloge, Seghieri, Josiane
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-06-2017; Springer Nature B.V; Springer Verlag
• Subjects: Agriculture; Agroforestry; Annual rainfall; Biomedical and Life Sciences; Continental interfaces, environment; Density; Dissipation; Dominant species; Dry forests; Dry season; Drying; Forestry; Forests; Life Sciences; Parks; Plant species; Population growth; Rainfall; Rainy season; Recycling; Rural areas; Rural populations; Sciences of the Universe; Seasonal variations; Seasons; Species composition; Transpiration; Trees; Sudan; Land use changes; Water use; Benin; Transient thermal dissipation method
• ISSN: 0167-4366; 1572-9680
• DOI: 10.1007/s10457-016-9937-8

Average population growth in the African Sudanian belt is 3 % per year. This leads to a significant increase in cultivated areas at the expense of fallows and forests. For centuries, rural populations have been practicing agroforestry dominated by
Vitellaria paradoxa
parklands. We wanted to know whether agroforestry can improve local rainfall recycling as well as forest. We compared transpiration and its seasonal variations between
Vitellaria paradoxa,
the dominant species in fallows, and
Isoberlinia doka
, the dominant species in dry forests in the Sudanian belt. The fallow and dry forest we studied are located in northwestern Benin, where average annual rainfall is 1200 mm. Sap flow density (SFD) was measured by transient thermal dissipation, from which tree transpiration was deduced. Transpiration of five trees per species was estimated by taking into account the radial profile of SFD. The effect of the species and of the season on transpiration was tested with a generalized linear mixed model. Over the three-year study period, daily transpiration of the agroforestry trees,
V. paradoxa
(diameters 8–38 cm) ranged between 4.4 and 26.8 L day
−1
while that of the forest trees,
I. doka,
(diameters 20–38 cm) ranged from 9.8 to 92.6 L day
−1
. Daily transpiration of
V. paradoxa
was significantly lower (15 %) in the dry season than in the rainy season, whereas daily transpiration by
I. doka
was significantly higher (13 %) in the dry season than in the rainy season. Our results indicate that the woody cover of agroforestry systems is less efficient in recycling local rainfall than forest cover, not only due to lower tree density but also to species composition.