Emergence, survival, and growth of recruits in a desert ecosystem with vegetation-induced dunes (nebkhas): A spatiotemporal analysis

摘要

We studied how emergence, survival, and growth of nebkha recruits are spatially affected by prevailing biotic and abiotic ecological drivers in a landscape with vegetation-induced dunes (nebkhas) in Saudi Arabia. Hereto Monte Carlo-based spatiotemporal analyses were performed on four remotely sensed study site maps, including adult nebkhas, recruits and elevation data, acquired over a three-year period. The emergence of new nebkha recruits was found substantially higher in topographic depressions and around adults, which we interpret as being a result of runoff water convergence to depressions and distance-limited seed dispersal from adults. The survival of recruits was also higher nearby nebkhas. However, the growth of already present recruits was suppressed near adult vegetation indicating competition, but unexpectedly increased far away from nebkhas which could be induced by augmented sand burial in these open areas, stimulating the nebkha development and its host plant. Combining the three demographic processes emergence, survival, and growth revealed systematically greater encroachment from nebkha recruits in zones with low vegetation cover, which creates a buffer against local disturbances in nebkha fields. (C) 2016 Elsevier Ltd. All rights reserved.