A mechanism of self‐organization in a desert with phytogenic mounds
| Autor: | Ivan Nijs, Magdy I. El-Bana, Saud L. Al-Rowaily, Abdulaziz M. Assaeed, Jan J. Quets, Stijn Temmerman |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
0106 biological sciences
nebkhas 010504 meteorology & atmospheric sciences media_common.quotation_subject ved/biology.organism_classification_rank.species Saudi Arabia plant shrinkage 010603 evolutionary biology 01 natural sciences Shrub lcsh:QH540-549.5 Precipitation Biology Ecology Evolution Behavior and Systematics 0105 earth and related environmental sciences media_common Ecology ved/biology spatial ecology Sediment Vegetation Chemistry Desertification Rhazya stricta Decne Spatial ecology Spatial variability Physical geography lcsh:Ecology Surface runoff Geology digital elevation model (DEM) |
| Zdroj: | Ecosphere, Vol 7, Iss 11, Pp n/a-n/a (2016) Ecosphere |
| ISSN: | 2150-8925 |
| Popis: | Phytogenic mounds or nebkhas are formed by spatially isolated burial-Tolerant plants, which have been trapping windborne sediment within their canopies. They occur in drylands all over the world, and nebkha landscapes are considered intermediate between stable grasslands and unstable deserts with mobile dunes. Depending on the previous state of the landscape, they can thus be viewed both as indicators of desertification and as signs of stabilization. While individual nebkha mounds have been studied extensively, little is known about the organization of nebkha landscapes. In this study, we collected spatiotemporal data of vegetation and topography from four self-made remotely sensed maps, created over a three-year period from a study site in central Saudi Arabia dominated by the nebkha-forming shrub Rhazya stricta Decne. Using logistic regressions and t tests, we found that the nebkha shrubs grow in topographic depressions, while they shrink on topographic highs and in locations with high nebkha densities. We propose that this spatial variation in nebkha growth is driven by water availability, as the few extreme rain events that typically make up the bulk of precipitation in deserts would spatially redistribute to topographic lows, and as nebkha density would positively correlate with competition for water. Our data suggest a novel mechanism of biogeomorphological self-organization in deserts. The observed nebkha growth in depressions would lead to increased sedimentation on and in between the nebkhas owing to reduced wind speed, which after a time lag might transform depressions into topographic highs on which nebkhas tend to shrink because of water shortage. Shrinking nebkhas, in turn, could provoke soil erosion, on as well as in between the nebkha mounds, which may ultimately transform topographic highs into depressions, thereby closing the cycle of self-organization. ispartof: Ecosphere vol:7 issue:11 status: published |
| Databáze: | OpenAIRE |
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