Plant Communities,Soil Carbon,and Soil Nitrogen Properties in a Successional Gradient of Sub-Alpine Meadows on the Eastern Tibetan Plateau of China |
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Authors: | Wen-Jin Li Jin-Hua Li Johannes M H Knops Gang Wang Ju-Jie Jia Yan-Yan Qin |
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Institution: | (1) Key Laboratory of Arid and Grassland Agroecology, Lanzhou University, Lanzhou, 730000, People’s Republic of China;(2) School of Biological Sciences, University of Nebraska, 348 Manter Hall, Lincoln, NE 68588-0118, USA |
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Abstract: | To assess the recovery trajectory and self-maintenance of restored ecosystems, a successional gradient (1, 3, 5, 15, and 30 years
after abandonment) was established in a sub-alpine meadow of the eastern Tibetan Plateau in China. Plant communities and soil
carbon and nitrogen properties were investigated and analyzed. Regression analyses were used to assess the models (linear
or quadratic) relating measures of species richness, soil carbon and nitrogen properties to fallow time. We found that species
richness (S) increased over the first 20 years but decreased thereafter, and aboveground biomass showed a linear increase
along the fallow time gradient. The richness of different functional groups (forb, grass and legume) changed little along
the fallow time gradient, but their corresponding above ground biomass showed the U-shaped, humped or linear pattern. Soil
microbial carbon (MBC) and nitrogen (MBN) in the upper 20 cm showed a U-shaped pattern along the fallow time gradient. However,
soil organic carbon (Corg) and total nitrogen (TN) in the soil at depth greater than 20 cm showed significant patterns of linear decline along the
fallow time gradient. The threshold models of species richness reflected best the recovery over the 15 year fallow period.
These results indicated that fallow time had a greater influence on development of the plant community than soil processes
in abandoned fields in sub-alpine meadow ecosystem. These results also suggested that although the succession process did
not significantly increase soil C, an increase in microbial biomass at the latter stage of succession could promote the decomposability
of plant litter. Therefore, abandoned fields in sub-alpine meadow ecosystem may have a high resilience and strong rehabilitating
capability under natural recovery condition. |
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