The possible role of Ziziphus lotus as an ecosystem engineer in semiarid landscapes

Positive interactions between nurse plants and their facilitated species are most notable in dry/high-elevation habitats. Plants that modify limiting resources or constraining variables creating an even stronger positive impact on the community are considered ecosystem engineers. Ziziphus lotus, a dominant deep-rooted shrub of arid/semi-arid Mediterranean habitats, can create fertile islets; most likely acting as a nurse plant. To further investigate its role as an ecosystem engineer, we assessed for Thymbra capitata the density of 1377 individuals and the night time-dehydration of 66 individuals, growing around 11 Z.lotus plants for three successive zones (0–5m, 5–10m and 10–15m) and for wetter and drier habitats created by topography in Cyprus. We discovered that T. capitata significantly increases in density (by c. 2.5 times) and can improve its night-time rehydration in mid-summer (by c. 60 times) when growing up to 5m around Z.lotus compared to thymes growing 10–15m away. Density and stem moisture for thymes growing near Z.lotus do not seem to be significantly affected by topography. Hence, Z.lotus may have properties to be classified as an ecosystem engineer and the potential to boost semiarid ecosystem productivity in the battle against desertification under global climatic change.