Abstract
Artemisia ordosica is an excellent sand-fixing shrub for sand stabilization in northwestern China. Sand dune stabilization, a critically important process, leads changes in abiotic factors, such as soil structure and nutrient contents. However, the effects of factors on an A. ordosica community following sand stabilization remain unclear. In this study, we used canonical correspondence analysis (CCA) to examine the relationships between A. ordosica communities and environmental factors at three habitats: semi-fixed dune (SF), fixed dune with low-coverage biological soil crust (F), and fixed dune with high-coverage biological soil crust (FC) in Mu Us desert. The mean height and coverage of plants increased with sand stabilization, while species diversity and richness increased initially and then reduced significantly. Correlation analysis and CCA revealed that slope, soil organic carbon, and nutrient contents, proportion of fine soil particles, soil moisture, and thickness of biological soil crust were all highly correlated with vegetation characteristics. These environmental factors could explain 40.42 % of the vegetation–environment relationships at the three habitats. The distribution of plant species was positively related to soil moisture in the SF dune. Soil moisture, soil nutrient, and fine-particle contents mainly affected plants distribution in the F dune. In the FC dune, distribution of plant species was positively and negatively correlated with the thickness of biological soil crust and soil moisture at a depth 0–20 cm, respectively. The dominance value of typical steppe species increased significantly following sand-dune stabilization and relations between species and samples in CCA ordination bi-plots showed that perennial grasses could invade the A. ordosica community on FC, indicating A. ordosica communities had a tendency to change into typical steppe vegetation with the further fixation. We conclude that the significant differentiation not only occurred in community characteristics, but also in the relationships between vegetation and environmental factors among the three stages of dune fixation. So, restoration of degraded dune ecosystems should be based on habitat conditions and ecological needs.
Highlights
The interaction between plants and the environment generates plant communities, and multiple environmental factors affect the spatial distribution of those communities (Borcard et al 1992)
The biological soil-crust conditions differed significantly following sand stabilization, and the biological soil crust thickness gradually increased with dune fixing
Our results showed that vegetation coverage and species richness within the A. ordosica communities are significantly correlated with soil factors
Summary
The interaction between plants and the environment generates plant communities, and multiple environmental factors affect the spatial distribution of those communities (Borcard et al 1992). For plant communities on sand dunes with the same climatic conditions, differences in habitat conditions following sand-dune stabilization may be the main cause of differences in the species composition and spatial distribution of plant communities (Li et al 2010, 2011a). Whether the relationships between distribution of plant species and environmental factors remain constant under different habitat conditions is still unclear. Vegetation coverage and species diversity are two important features of plant communities. In-depth analysis of the relationships between the vegetation characteristics (including vegetation distribution, vegetation coverage, and plant-species diversity) and environmental factors during sand stabilization can provide important information related to the management of desert vegetation communities, and protection and restoration of arid and semi-arid sand dune ecosystems
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