| 其他摘要 | The Loess Plateau is well known for its severe soil erosion. Soil erosion severely
interferes with the process of plant development and succession. In this serious soil erosion
region, plants can overcome stress and disturbance due to soil erosion through different
survival strategies, and developed into plant communities that could resist soil erosion.
This study was based on several years’ vegetation survey data of the Yan River basin in the
hilly and gully region of the Loess Plateau. The definition of erosion-resistant species and
Braun-Blanquet phytosociology methods were used to select potential erosion-resistant
species. The community species composition of different recovery stages, plant growth and
reproductive form characteristic, and plant niche breadth were used to explore its
adaptation mechanism and its role in the plant community, and to analyze the evolvement
rule of different erosion-resistant species. Plant community survey and analysis data under
different soil erosion environments were used to elucidate the ability of different
erosion-resistant plant communities to improve soil erosion environment in the vegetation
recovery process. Plant community structure vegetation cover index and soil erosion data
in different erosion-resistant plant communities were used to illuminate the community
structure characteristics that could resist soil erosion. The main results are as follows:
1) A total of 42 potential erosion-resistant species were selected, which belong to 18
families and 33 genera. Gramineae, Leguminosae, Compositae, Rosaceae occupied the
dominant position in the study area; they were the main species in vegetation restoration
succession process. Due to the climate in this region, the plant growth form was given
priority to with shrub and herbs. Shrubs were mostly phanerophyte and chamaephytes, and
herbs were dominant by hemicryptophytes. Plant water ecological type was given priority to with mesophyte and xerophytes.
2) Forty-two potential erosion-resistant species maintained their own survival and
reproduction through soil seed bank, plant crown seed bank, seed germination and
dormancy strategies, seedling planting and vegetative propagation. They could adapt to
environmental erosion by one or several mechanism of the special structure of anatomical
morphology, thick protective tissue, developed palisade tissue, antioxidant mechanism and
osmotic adjustment. The ecological niche breadth of different erosion-resistant species was
from 0.023 to 0.359. The erosion-resistant species could be regarded as dominant species
or accompanying species in the suitable habitat, it was an occasional species in other
habitats.
3) In the process of natural vegetation recovery, the erosion-resistant species began to
habitat differentiation in herbaceous community late succession stages. Tree and shrub
distributed in local region along gully slope, shoulder line of valley, etc of forest zone and
forest steppe zone of Yan river basin, respectively. Shrub rarely appeared in steppe zone of
Yan river basin. In the process of understory vegetation restoration under Robinia
pseudoacacia plantation, the erosion-resistant species was less, only some annual weeds
and Gramineous plants appeared under plantation. After Robinia pseudoacacia plantation
decline, the mid and late stage species were the dominant species under plantation. During
the period of relatively stable growth of the shrub plantation, there was no replacement of
erosion-resistant species under plantation.
4) The suitable community structure, which was formed by many species, was
particularly important. The ground and underground complex hierarchical structure formed
by different species could effectively improve soil environment. In addition, the
improvement ability of erosion-resistant plant community was closely related to its habitat.
In forest zone, phytocenosium structure formed by tree, shrub, herbs, and more litter were
the main factors to improve soil environment. In forest steppe zone and steppe zone, plant
fine root was the key factor to improve soil environment.
5) Different communities have their own suitable structure vegetation cover index (Cs)
that could effectively reduce soil erosion intensity. Early succession community and
afforestation did not show a strong erosion-resistant, when the Cs were more than 20% and
30% respectively, and that the cover of herb layer and litter layer was higher, the soil erosion intensity was less than 2500 t km -2 yr -1 . When Cs of mid and late succession
communities, and natural tree and shrub communities were more than 30%, and 36%
respectively, and that at least one of the cover of near surface layers (shrub, herb, litter
layer) was higher, these communities could be effective in reducing soil erosion. Especially
in the year of rainstorm, Gramineous plant communities and natural tree and shrub
communities could effectively control soil erosion, when the Cs of these communities were
more than 38% and 30-40%, respectively, and that at least one of the cover of near surface
layers was higher, soil erosion intensity was smaller than soil loss tolerance in the Loess
Plateau Region. The Cs value that community could effectively resist soil erosion had
obvious difference in different hydrological years. In the year of rainstorm, the
communities need to have higher Cs value when it was able to effectively reduce soil
erosion.
Key Words: erosion-resistant plant; vegetation succession; community structure
characteristics; ecological niche breadth; soil erosion |
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