| The conflicts between human and environments are remarkable in karst area where the soil impoverishment and rocky desertification are frequently encountered.Environmental issues in karst area have always been one of the hot topics in scientific researches.Among them,restoration and reconstruction of degraded karst vegetation is one of the key issues in ecological researches of karst area.In this paper,the dolomite and limestone,two most widely distributed rocks in karst area,are investigated and analyzed by community-based methods,experimental methods,analytic hierarchy process(AHP)methods,and fuzzy mathematics comprehensive assessment method.Then,ten species with excellent adaptability and ornamental characteristics in the stage of grass-shrub community are carefully chose for further study by orthogonal test.The following conclusions can be drawn:(1)The characteristics of rocky environments in karst area and key technologies for their further development can be inferred from our experimental and numerical studies.Several conclusions are given as follows:(1)the fractal theory and spatial syntax theory are used to reveal the fractures’ configurations and structural characteristics of rock structural faces;(2)based on our revealed characteristics and the characteristics of primary matrix obtained from field investigation,the plants are grown in the fractures to fully absorb water and nutrients in both fractures and matrix.Additionally,the floristic composition and characteristic of community configurations obtained from the field investigation of similar native habitats and the results of this study are set as the benchmarks to cultivate the plants.(2)Based on the above-mentioned rock habitat simulation technology,combining with the results of field investigation on the characteristics of plant community matrix,rock type,species,pattern,pattern and scale in grass-shrub stage,a suitable karst-like rock habitat community was constructed.The key points of its allocation were as follows: to investigate and analyze the rock habitat,taking the principle of protozoa(protozoa,protozoa)and adaptability as the principle,and taking karst area as the basis.Based on the most widely distributed dolomite,thick limestone and thin limestone facets and fissures,plant communities are allocated vertically and horizontally.In vertical space,shrub grass,rattan grass and rattan shrub grass were used as plant community collocation patterns;in horizontal space,1m×1m,2m×2m and 3m×3m were used as community scale;and in aggregation,random and uniform species pattern,suitable communities were constructed to imitate karst rocky habitats.Based on simulated habitats and communities,the simulated rocky habitat communities were cultivated by conventional plant cultivation techniques.(3)Based on above experimental studies on rocky habitats,after consideration of the results from field investigation on the matrix characteristics,rock types,species,configurations,patterns and physical scales in the stage of grass-shrub community,the artificial habitat and environments that are similar to rocky habitats in karst area are constructed.The configurations of habitats are set as follows.Firstly,the rocky habitats are investigated and analyzed in detail.Then,following the principles of originality(original species,original rocks)and adaptability,the plant communities are grown vertically and horizontally in rocky habitats and fractures of structural faces in dolomite,thick limestone and thin limestone,which are the most widely distributed rocks in karst area.Specifically,in vertical direction,the plant communities are mainly composed of shrub grass,rattan grass and rattan shrub grass;in horizontal space,the community scales are set with 1m×1m、2m×2m 和 3m×3m.Moreover,the artificial habitats are established in aggregation,random and uniform distributed patterns to imitate karst rocky habitats.Based on the self-constructed rocky habitats and communities,the species and communities in artificial rocky habitats are cultivated by conventional plant cultivation techniques.(4)The indexes that can reveal rocky habitats,soil nutrients,microorganisms,species’ configurations and structure,and ecological service function are determined by Delphi method to construct an evaluation system of technology for cultivating plant in grass-shrub communities of rocky habitats.Then,the technological systems for cultivating plant in landscape restoration of grass-shrub community in rocky habitats are evaluated by analytic hierarchy process(AHP)and fuzzy mathematics comprehensive assessment method,pointing out the key factors affecting the development and change of plant communities,such as the integration degree,porosity and landscape aesthetic degree of community,soil microorganism,soil moisture and soil temperature,which require to be taken into account in landscape restoration of grassland-shrub communities.Based on the research results of simulating karst rocky habitats,the key points of community allocation in karst rocky habitats are deduced in this paper: a.Larger-scale communities have better ecological and social benefits.Horizontal and vertical collocation models can be used to make full use of the habitat resources in areas with limited plane space;B.Hydrothermal control energy of dolomite and thin-layer Limestone Habitats Strong ability can effectively improve community habitat space and indirectly promote community development.For thick Limestone Habitats with weak regulation ability,species with strong habitat transformation,strong adaptability,fast growth and multiple reproduction characteristics can be selected to construct community,such as Pueraria lobata;C.Under species aggregation and uniform distribution,plants can promote community by constructing intraspecific competition relationship.The formation of fallen form and structure can improve the anti-interference ability of community;D.The spatial structure of vine shrub grass and shrub grass communities is perfect,and the stratification phenomenon is obvious.Water and heat are intercepted in space to provide a buffer zone for the lower space,so that the lower space of community tends to be stable,which plays an active role in the transformation of habitats and promotes the transformation of micro-system of rocky habitats to a stable direction;E.Firethorn and hypericum.Coriaria,Pueraria lobata,Eriobotrya sibirica have strong adaptability and transformation ability to habitats,grow fast,cover high degree,and have good ornamental value.They are suitable species for landscape restoration of karst rocky habitats and can be popularized and utilized.The above results are of great significance to plant allocation of herbage and shrub communities in karst rocky habitat landscape restoration.(5)Using fractal theory and spatial syntax theory,it is revealed that the fractures in structural faces of dolomite have the characteristics of clear hierarchy,discontinuum,fragmentation,tight connection and strong control;the pore structures and fractures in limestone have the characteristics of fuzzy hierarchy,poor connectivity,weak system and strong heterogeneity.The configurations of pore structures and fractures in the structural faces of rocks experience a great difference,so do the species communities.According to these differences,10 species including pyracantha,hypericum were selected for orthogonal test that aims at designing and constructing bionic community for species.It is observed that shrub-grass and rattan shrub grass communities grow rapidly in the vertical direction,while rattan grass grow rapidly in the horizontal direction.The coverage of rattan-shrub-grass and rattan-grass communities is large,and physical scale of communities,habitat types and configuration patterns influence greatly the community height.As a whole,the growth direction of community transform towards the congregation(congregation pattern)direction,and the transformation rate of growth direction is quite different.Pueraria lobata,hippophae rhamnoides and hypericum have the best adaptability to habitats,while coriaria,akebia trifoliate and dendrocalamus nandinata are not easily adapted to new environments.Elymus sibiricus and commelina communis have acceptable habitat adaptability,while the remaining herbs have a low survival rate.Adaptability of plants to habitats are mainly realized by adjusting ground’s diameter and biomass proportion.Soil moisture is remarkably negatively correlated with soil temperature.Soil nutrients in the artificial rocky habitats are significantly inadequate,specifically,the contents of N,P and K are generally lower than the average level of karst habitats,and SOC gradually decrease over time,greatly affected by community scale.Rock type,configuration pattern and community scale have great influence on K content.Actinomycetes is closely related with soil pH,and soil bacteria gradually decreases over time.Pore structures and fissure characteristics in rocks have weak correlation with soil’s related indexes and community indexes,while a strong correlation between soil indexes and community indexes is observed.The scenic beauty values of community,water conservation ability and carbon sequestration capacity are affected by multiple factors.Moreover,the carbon sequestration capacity of pueraria lobata,pyracantha fortunei,cortex mori and hypericum japonicum is excellent. |
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