Liu Hujun

The succession and spatial structure of vegetation on desertified land in arid area

It is well known that man-assisted revegetation is one of the most effective methods to stabilize sand dunes, promote biodiversity, reduce the damages of desertification and hence reverse the course of desertification. The objectives of this study were to monitor the succession and changes in spatial structure of the vegetation after establishment of revegetation on windward sand dunes in arid area of Northwestern China, where the average annual rainfall is 160 mm. Field observations revealed that during the past 20 years, the main vegetation community has undergone a series of changes from herbages to herbages + Hedysarum scoparium to herbages + H. scoparium + Artemisia ordosica to Artemisia ordosica + herbages. In the diluvium and alluvium based sandy areas where the Nitraria tangutorum was the dominant species, the vegetation have had the succession from Nitraria tangutorum + herbages to Nitraria tangutorum + herbages + Artemisia ordosica to Artemisia ordosica + herbages + Nitraria tangutorum to Asterothamnus centrali + Stipa gobica + Artemisia ordosica. It is clear that, with the degradation of the man-assisted revegetation, e.g. H. scoparium, the natural species, such as Artemisia ordosica and herbages have dominated the communities. With the succession of the dominant species, the spatial structure of the plants has tended to concentrate to the height of 20-60 cm. Results revealed that the feasibility of sand dune fixation not only relates to the coverage of vegetation, but also to the spatial structure of the plants.