Arbuscular mycorrhiza and water and nutrient supply differently impact seedling performance of dry woodland species with different acquisition strategies

Abstract

Background: Arbuscular mycorrhizal (AM) fungi increase seedling survival and performance through enhancement of nutrient and water uptake under stress conditions. Acacia etbaica, A. senegal and Boswellia papyrifera dominate large areas in African drylands where both moisture and nutrients are limited.

Aims: We evaluated the effects of AM, drought and soil quality on carbon gain (growth), gas exchange and nutrient contents of seedlings of these three dry woodland species.

Methods: We used a greenhouse experiment with a fully factorial design of two levels of AM, two levels of soil and four levels of water availability, on the carbon gain, gas exchange and nutrient content of seedlings of the three species.

Results: AM symbiosis enhanced the acquisition of water and nutrients and increased gas exchange resulting in increased Acacia and Boswellia seedling biomass. The rapidly growing Acacia species (acquisitive strategy) showed larger mycorrhizal benefit at higher water availability. The slow-growing Boswellia (conservative strategy), in contrast, showed larger mycorrhizal benefit at lower water availability.

Conclusions: This study showed that different species of dry woodlands benefit from AM in different ways depending on the resource use strategy under stress conditions. The inclusion of the mycorrhizal habit in trait-based approaches increases understanding of functional differences of coexisting tree species.

Keywords:

• Acacia
• Boswellia
• plant strategy
• trait-based ecology
• water deficit

Acknowledgements

We are grateful to two anonymous referees and to Dr Laszlo Nagy for constructive comments on an earlier version of this manuscript. Emiru Birhane was granted study leave from Mekelle University. We thank Mekelle University and the Department of Biology, Addis Ababa University for provision of chemical support.

Additional information

Funding

Emiru Birhane was supported by a sandwich Ph.D. grant from Wageningen University, and by research grants from the Norwegian Aid [NORAD II] project, International Foundation for Science, and the Netherland Fellowship programme NUFFIC. The work for this study was also supported by the Netherlands Organization for Scientific Research - Science for Global Development [NWO-WOTRO] through the integrated program FRAME - ‘Frankincense, myrrh and gum arabic: sustainable use of dry woodlands resources in Ethiopia’.

Notes on contributors

Emiru Birhane

Emiru Birhane is an associate professor. His main interest is in the ecology of forests and trees and mycorrhizal ecology.

Thomas W. Kuyper

Thomas W. Kuyper is a professor. His main interest is in the ecology and diversity of fungi. He has worked on mycorrhizal associations (both arbuscular mycorrhiza and ectomycorrhiza) in temperate and tropical areas.

Frank J. Sterck

Frank J. Sterck is an assistant professor. His main interest is in the ecology of trees and forests. He aims at understanding growth, niches and distributions of tree species from underlying physiological and evolutionary principles.

Kindeya Gebrehiwot

Kindeya Gebrehiwot is an associate professor in forest ecology.

Frans Bongers

Frans Bongers is professor in tropical forest ecology.