Plant Communities, Soil Carbon, and Soil Nitrogen Properties in a Successional Gradient of Sub-Alpine Meadows on the Eastern Tibetan Plateau of China

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 (C(org)) 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.

Functional groups and dispersal strategies as guides for predicting vegetation dynamics on reclaimed mines

“…As the richness of perennial grasses was relatively constant through time, this pattern of perennial herbs richness was caused mainly by a unimodal response of forbs richness. Similar results have been reported in restored sub-alpine meadows (Li et al 2009). …”

Contrasting responses in leaf nutrient-use strategies of two dominant grass species along a 30-yr temperate steppe grazing exclusion chronosequence

“…Further, both leaf N and P concentrations of S. grandis decreased along the restoration gradient and its leaf N:P ratio also tended to decrease, suggesting lower access of S. grandis to both nutrients and a more strongly limited access to N relative to P. Different plant species preferentially take up different forms of N (McKane et al 2002) and the same is also likely for P (Turner 2008). This decoupling between soil inorganic nutrients and the leaf N, P and N:P ratios of the two grass species can therefore stem from potential changes in the forms of soil extractable N and P along the gradient as soil organic matter becomes progressively dominated by plant litter rather than by animal faeces (He et al 2009;Li et al 2009). Alternatively, these species-specific responses may stem from an increase in plant competition intensity along the restoration gradient (Gao et al 2009).…”

“…In the temperate steppe of Inner Mongolia for instance, grazing exclusion significantly enhances total yearly cumulative net N mineralization (Shan et al 2011). However, slower soil N mineralization rates and lower soil inorganic N availability have been reported in other restored grasslands (Baer et al 2002;Li et al 2009;MedinaRoldan et al 2012).…”

Magnitude of Species Diversity Effect on Aboveground Plant Biomass Increases Through Successional Time of Abandoned Farmlands on the Eastern Tibetan Plateau of China

“…Furthermore, studies that examine only part of the successional sequence have identify a positive (early succession), negative (late succession), or no clear relationship (transitional stage or the habitat is undergoing continuous disturbances) (Peet, ). Our previous work has shown that species richness increased in a hump‐shaped pattern, and aboveground biomass showed a linear increase along the successional gradient (Li et al ., ). Here, we examine how species diversity is related to plant biomass within different successional stages.…”