Stable carbon isotope composition (delta C-13) of Acacia tortilis subsp spirocarpa (A Rich) Brenan growing at three semi-arid sites in Kenya

Carbon isotope ratios (delta(13)C) were obtained from foliage and branch wood samples of Acacia tortilis grown with and without microbial inoculation, on three semi-arid sites in Kenya. delta(13)C ratios were higher in trees grown on the two drier sites than on the wetter site. In addition, delta(13)C ratios of seedlings inoculated with a mixed microbial inoculum (VA mycorrhiza with rhizobia) were higher than uninoculated controls at the wetter site. These preliminary results suggest that Acacia tortilis trees growing on drier sites display relatively high water-use efficiencies, and that in some situations microbial inoculation may increase water-use efficiency of outplanted trees. (C) 1996 Academic Press Limited