The Multi-scale Effects Of Landscape Heterogeneity On Plant Species Diversity

Landscape ecology, landscape heterogeneity is the basis of study, ecosystem services isthe final result, biodiversity is the ties of landscape ecological pattern and ecosystem services.Non-agricultural plant is the most important part of the non-agricultural habitats, the existence ofwhich has an important role in agricultural landscape ecological system process, function, serviceand maintain.The study area is in Gongyi city which is distributed in the mountainous and hilly areasof Middle-Lower Yellow River. We select three types of habitat, such as shrub, plantation andfarmland to investigate plant species by the typical sample method. These three types of habitatalso represent three different disturbance levels. Shrub corresponds to the natural habitat,plantation is under semi-natural habitat, and the farmland habitat is under the strongest humandisturbance level. Based on the actual situation and investigation, we develop the landscapeclassification system. The landscape of study area is divided into: irrigable landscapes, drylandscape, orchard landscape, woodland landscape, shrub landscape, grassland landscape, riverlandscape, ponds landscape, ditches landscape, beach landscape, landscape construction land,roads and bare landscape, a total of13kinds of landscape types, which can represent the actualsituation of Gongyi City.First, we analyse the differences between heterogeneous community characteristics ofthe study area and species diversity in different habitats. Then we analyse of spatial temporaldynamics of landscape heterogeneity from1990to2011. Last, Based on the principles ofLandscape Ecology, under the technical support of Geographic Information System (GIS), each sample plot is considered as the center to set different radius (150m,250m,500m,750m,1000m,1250m and1500m) of buffers. In each buffer, we extract six classes of landscape metrics, whichinclude patch shape、edge contrast、similarity and proximity、landscape diversity、texture、patchsize and patch density, a total of52landscape metrics. By applying the redundancy analysis(RDA), the landscape metrics that affect plant species diversity significantly in agriculturelandscape are extracted from different scales. The results as followed.(1) Research shows that the non-agricultural habitats in agricultural landscape of themountainous and hilly areas of Middle-Lower Yellow River has high in species composition, butdifferent habitats have difference. Shrub habitat has the highest diversity and richness, plantationhabitat has higher community coverage, the biggest change in the magnitude and degree ofdifferentiation farmland edge community composition (β diversity index maximum). Communitysimilarity analysis shows that plantation and farmland have higher inter-community similarity,while shrubs as a natural habitat, has lower inter-community similarity attributable mainly tospecies characteristics.(2) Agricultural landscape is the main landscape type in Gongyi City for a long time,and landscape matrix is the dry land. Nearly20years, the dry landscape areas reduce about10%, asignificantly increase in construction sites and road landscape area. In the plains and river areas,the mainly landscape types is irrigable landscapes, dry land landscape, construction land. In thehilly areas, dry land landscape is the dominant landscape, the area of which is19346.45hm2,accounting for42.91%of the total area, followed by the construction land landscape. Thelandscape type of the low mountain areas is similar to the hilly areas, the dominant landscapetypes is plantation. (3) We select the Shannon’s diversity index (SHDI), Shannon’s evenness index(SHEI)and contagion index (CONT) to analysis landscape spatial compostion and configurationheterogeneity. The Shannon’s evenness index(SHEI) of the overall landscape is0.7483, contagionindex (CONT) is58.6841, Shannon’s diversity index (SHDI) is1.9194, the edge contrast index(ECON_MN) of73.8974. Each index will fluctuate between different geomorphic types.(4) Through the analysis of the RDA, the result shows that different extent, therelationship between landscape metrics and species diversity changes significantly. In terms ofshrub habitat, the landscape metrics of SHAPE_AM and PARA_AM can well support the speciesdiversity at the extent of500m-750m, and the cumulative percentage variance can get to33.6%.For plantation habitat, the landscape metrics of SHAPE_AM, AREA_CV, SIMI and PAFRAC canwell explain the species diversity at the extent of1000m-1250m, and the cumulative percentagevariance is48.1%. For farmland edge habitat, the GYRATE_CV, ENN_CV, PARA_AM andFRAC_AM are major metrics have strong relationship with species diversity, and the cumulativepercentage variance is32%. At the extent of750m-1250m, Simpson’s diversity index (SIDI)shows significant relation with shrub plants; while the metric of ENN_CV only has correlationwith farmland plants at the extent of1000m-1250m.(5) This study indicates that the effects of landscape heterogeneity on plant speciesdiversity are strongly depended on the spatial dependency, we recommend further research aboutscale effects of the landscape metrics and much more application studies of these metrics inLandscape Ecology.