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- Title
Changes in soil organic carbon fractions after afforestation with xerophytic shrubs in the Tengger Desert, northern China.
- Authors
Li, X. J.; Li, X. R.; Wang, X. P.; Yang, H. T.
- Abstract
Afforestation is an important means of controlling desertification and of restoring vegetation on land that has become desert. The procedure leads to changes in the dynamics of organic carbon ( C) in the soil as xerophytic shrubs are established, but the dynamics are still poorly understood, partly because of the lack of long-term observations. Progressive measures to bind sand dunes along the route of the Baotou- Lanzhou railway on the south eastern edge of the Tengger Desert in China, which were begun in 1956, provide the opportunity to study such changes. We sampled the topsoil (0-10 cm) from 10 sites that represent a chronosequence and vary in age from 1 to 57 years since sand-binding measures and afforestation were begun. These measures evidently trapped increasing amounts of clay and silt, and with them increased the concentrations of both available phosphorus ( P) and available potassium ( K). By analysing the organic C in the samples we have been able to describe quantitatively the changes in several C fractions over time. We found that total C, its light and heavy fractions, dissolved C and microbial C all increase slowly at first after afforestation, then more rapidly, and then at a decreasing rate. They seem to be examples of logistic growth and could be described by logistic equations. The light fraction increased faster than the total C, as did the microbial C during the first 19 years. The light C fraction was the most sensitive for identifying changes in soil C after afforestation. Over the full 57 years, the contributions of the light and microbial fractions to total C increased, while those of the heavy fraction and dissolved C decreased. Our results suggest that the proportion of C in labile pools increased, but the proportion in stable pools decreased, which would increase the risk of substantial losses of C caused by potential global warming and human-induced disturbances.
- Subjects
CARBON in soils; HUMUS; FRACTIONS; AFFORESTATION -- Environmental aspects; SHRUBLANDS; DESERTIFICATION control; MATHEMATICAL models
- Publication
European Journal of Soil Science, 2016, Vol 67, Issue 2, p184
- ISSN
1351-0754
- Publication type
Article
- DOI
10.1111/ejss.12315