Adaptation of five co-occurring tree and shrub species to water stress and its implication in restoration of degraded lands

BACKGROUND

Rift valleys of open savanna woodlands in Ethiopia are affected by increasing human activities such as deforestation and overgrazing. Programs to restore degraded habitats have failed due to a lack of knowledge about the ecology of indigenous species and soil water dynamics (water uptake patterns, the physiological response of species to water stress, and their tolerance scope under severe stress). Understanding the habitat requirements of species and the various soil water parameters such as water potential, leaf relative water content, and gas exchange are key to successfully restoring these areas. This article compares how tree species adapt to water stress and their potential for restoring degraded lands in Eastern and Southern Ethiopia.

RESEARCH GOALS AND METHODS

This study compared the adaptation of common tree and shrub species, such as Acacia tortilis, Acacia seyal, Acacia senegal (L.) Wild, Dichrostachys cinerea and Balanites aegyptiaca (L.) Del to water stress, their resilience under severe stress, and the impact of disturbances on the water conditions of species and sites. The authors used a random sampling technique to select tree species from each site and a pressure chamber to measure water potential (the potential energy of soil water per unit volume relative to pure water) across four sites. This study tested the species' water potential, rooting patterns, and annual growth increments.

CONCLUSIONS AND TAKEAWAYS

Based on this study, measuring the water potential values of species in water-scarce areas can serve as indicators of the site water conditions. This, in turn, can be used to match species with appropriate sites during restoration programs. Species respond differently to water stress; hence, this should be considered when selecting species for certain sites. Species such as Acacia tortilis and Balantites aegyptiaca can conserve water and are drought-tolerant. As such, they should be considered for restoring drought-prone degraded habitats.