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Li C.L.,State Key Laboratory of Desertification and Aeolian Sand Disaster Combating | Li C.L.,Research Station on Ecosystem of Desertification Rangeland | Li C.L.,Desert Research Institute | Xu X.Y.,State Key Laboratory of Desertification and Aeolian Sand Disaster Combating | And 8 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

Maqu alpine meadow is the important part of the Qinghai-Tibet Plateau and the main water conservation area in the upper reaches of Yellow River. But in recent years, the problems of the sandy desertification and soil erosion have become a serious threat to the ecological safety of the alpine meadow in the Qinghai-Tibet Plateau. To solve these problems, this paper examined the vegetation structure characteristics and the variation of α and β diversity on the potential, slight, moderate and serve desertification meadows in Maqu alpine meadows using sampling survey methods from July to September 2008. The results showed that in the desertification processes of Mqu alpine meadows, 1) the community coverage dropped gradually(99.216%, 80.078%, 49.895% and 36.398%, respectively), the species number also reduced gradually(53,32,14,13, respectively), community structure took a trend of simplification(the number of the dominant species were 28,16,10,8, respectively). The typical dominant and companion species of the alpine meadow also withdrew from the communities gradually, and the species adapted to the sandy environment occupied an important position in these plant communities. The typical Maqu alpine meadow ecosystem was gradually changing to the desertification alpine ecosystem, and experienced four stages, i.e.,Carex moorcroftii+Poa alpina communities→Carex moorcroftii +Saposhnikovia divaricata+Kobresia pygmaea communities→Kobresia pygmaea+Saposhnikovia divaricata+Carex moorcroftii communities→Leymus paboanus+Corispermum tibeticum+Carex moorcroftii+Saposhnikovia divaricata communities. 2)The species richness, Shannon-Wiener indexes and Simpson indexes were declining significantly. The Pielou evenness indexes and Alatalo evenness indexes showed a decreasing trend following the first increasing, and it reached the maximum in the slight desertification meadow, but their differences were not significant. The dominant index was increasing significantly, and there was extremely significant difference between the moderate desertification meadow and the slight one. 3) In terms of Whittaker index, there were extremely significant differences between the potential desertification meadow and other three ones, and there was significant difference between the moderate desertification meadow and the severe one, whereas there was no difference between the slight desertification meadow and the moderate one. 4) The community dissimilarity coefficient between the potential desertification meadow and other three ones were greater (the value in the range of 0.705-0.937), while the community common indexes between them were lower (the value in the range of 0.034-0.173), and the trend between the slight desertification meadow and the severe one was similar. However, the community dissimilarity coefficients between the moderate desertification meadow and severe one and the slight desertification meadow and the moderate one were lower (the value in the range of 0.545-0.553), and the community common indexes were higher (the value in the range of 0.293-0.303). The analysis from all the results revealed that the slight and severe desertification stages were the most important phases in the desertification process of Maqu alpine meadow. So, the potential desertification meadow must be protected and managed scientifically in order to prevent desertification from occurring. Artificial measures, e.g., enclosure, rotational grazing and tending were applied. However, in the sandy desertification meadows, vegetation restoration measures, such as turf transplantation, reseeding, fertilization as well as sand control measures must be taken to prevent the exacerbating and spreading of desertification.


Li C.-L.,Research Station on Ecosystem of Desertification Rangeland | Li C.-L.,Gansu Key Laboratory of Desertification and Sandstorm Disaster Combating | Li C.-L.,Desert Research Institute | Xiao B.,Gansu Key Laboratory of Desertification and Sandstorm Disaster Combating | And 8 more authors.
Chinese Journal of Ecology | Year: 2011

Taking the natural vegetations on the salinized fields having been abandoned for different years in the lower reaches of Shiyang River as test objects, this paper studied the dynamic changes and interrelationships of vegetation succession and soil nutrients. Overall, the vegetation type experienced three stages, i. e., field weeds → desert herbages → desert brushes, while the community succession had four stages, i. e., Convolvulus arvensis + Chenopodium album (1-2 years) → Peganum nigellastrum (3-10 years) → Lycium ruthenicum + Kalidium cuspidatum var. sinicum (10-40 years) → Kalidium cuspidatum var. sinicum (climax community). During community succession, the changes of soil nutrients experienced three stages, i. e., consuming → accumulating → consuming, only soil available K not consumed at the early stage. All soil nutrients were consumed at the late stage, and finally, their contents were approached to the levels under natural vegetations in the area. Because of the consuming of the soil nutrients at the early stage, P. nigellastrum had less contribution to the soil nutrients, being significantly negatively correlated with soil available P but positively correlated with soil available K. L. ruthenicum had positive correlations with soil nutrients, especially with soil organic matter, total N, and the available K in 30-60 cm layer. There were significant negative correlations between K. cuspidatum var. sinicum and soil nutrients, suggesting that K. cuspidatum var. sinicum had strong adaptation to the site conditions, being able to be the proper introducing species to accelerate and direct the vegetation succession on abandoned salinized fields.

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