Research On Plant Diversity And It’s Dynamics Along The Environmental Gradient In Henan Province Seetion Of The Yellow River Basin

A long-term goal of the International Geosphere-Biosphere Program (IGBP) is toestablish a Dynamic Global Vegetation Model (DGVM). The plot is located in the north-southclimate transition zones in Henan Province section of the Yellow River basin. The dynamicsof plant diversity in Henan Province section of the Yellow River basin are the results of thehistorical natural and anthropogenic activities. Thus, it plays a vital part in conserving globalbiodiversity and maintaining global ecosystem function.Over the past thirty years, the local people have conducted a mass exploitation on naturalresources, leading to significant changes in the local watershed ecosystem structure whichalso means the obvious changes of land use, habitat, biodiversity, and watershed ecosystemstability. They also deeply influence the local watershed ecosystem function. Understandingthese dynamic changes of plant biodiversity and the causes of these dynamics is essential forthe further research of local ecosystem functions and the goal of sustainable development inthe context of biodiversity conservation. Previous studies show the relationship betweendisturbance and biodiversity (intermediate disturbance hypothesis), for bio-protection,disturbances (frequency and intensity) are a main goal of relevance. This study was conductedin Henan Province section of the Yellow River basin. We conducted a research on the plantspecies diversity, plant community diversity, and did analysis toward the relationshipsbetween their herb species flow distributions and different environmental factors.By employing community ecology techniques, the study examined how theenvironmental factors influence the dynamics of plant biodiversity on the level ofenvironmental gradient in Henan section of the Yellow River. This study is carried on with theherb species of different landscape types (mountain, hill, plain) as its research object. Thecommunity research is conducted in the year of2009-2011and the distribution types of herbsalong environmental gradient are summarized by analyzing the plant species distribution, theflow feature of species along environmental gradient. The results of the research indicatedthat:1. There are50plant community types in the range of50km where Henan Provincesection of the Yellow River basin is perpendicular to the banks of the river. Jaccard Index(species similarity index) and Simpson Index showed increasing; Code Index (species replacement rate index) showed decreasing along elevation gradient decreasing. JaccardIndex (species similarity index) and Simpson Index and Code Index were significantlycorrelated with elevation (P<0.05or P<0.01). The order of plant communities Simpson Indexis: mountain>hill>plain. Plant species research in the year of2009-2011in Henan section ofthe Yellow River includes54families,159generas, and241species.2. Due to the changes of species and intensity of interference in different seasons,therefore, the diversity index of plant will decrease as the increasement of number of differentlandscape types.(1) Because the order sample number of herbicide used in farmland in four seasons(spring, summer, fall, and winter) is mountain>hills>plain, therefore, Simpson Index of herbspecies showed decreasing in the farmland ecosystem along environment (longitude, elevationand disturbance) gradient changes of mountain, hills, and plain in four seasons.(2) Due to the number of sample plots for grazing in the wetland is plain>hills>mountain,therefore, Simpson Index of herb species showed decreasing along mountain, hills, and plaindifferent environment (longitude, elevation and disturbance) gradient of changes. For thenumber of sample plots for water flooded in the wetland is mountain>hills>plain, SimpsonIndex of herb species showed increasing along environment (longitude, elevation anddisturbance) gradient changes of mountain, hills, and plain. Due to the number of sampleplots for iceing in the wetland is mountain>hills>plain, therefore, Simpson Index of herbspecies showed increasing along environment (longitude, elevation and disturbance) gradientchanges of mountain, hills, and plain.(3) Due to the number of sample plots for grazing in plantation and abandoned farmlandis plain> hills>mountain, therefore, Simpson Index of herb species showed decreasing alongenvironment (longitude, elevation and disturbance) gradient changes of mountain, hills, andplain in spring, summer and autumn. Because the number of sample plots of fireing inplantation and abandoned farmland is mountain>hills>plain, Simpson Index of herb speciesshowed increasing along environment (longitude, elevation and disturbance) gradient changesof mountain, hills, and plain in winter.(4) Because the intensity order of shrub-grassland ecosystem in soil and water loss offour (spring, summer, fall, and winter) is hills>mountain, therefore, Simpson Index of herbspecies showed decreasing along environment (longitude, elevation and disturbance) gradientchanges of mountain and hills in shrub-grassland in spring, summer, autumn, and winter.3. Jaccard Index (species similarity index) of herb species mostly shows the trend of the parabola dynamic change, Code Index (species replacement rate index) of herb species mostlypresents inverted parabolic dynamic change in different ecosystems. Seasonal changes of herbspecies number is: summer>spring>autumn> winter.4. In different ecosystems, the similarity and replacement rate of herbs in differentseasons are different:(1) Jaccard Index (species similarity index) of size sort: plantation and farmland>abandoned farmland and farmland>plantation and abandoned farmland>plantation andwetland>wetland and farmland>wetland and abandoned farmland in spring. Code Index(species replacement rate index) of size sort: wetland and abandoned farmland>wetland andfarmland>plantation and wetland>plantation and abandoned farmland>abandoned farmlandand farmland>plantation and farmland in spring.(2) Jaccard Index (species similarity index) of size sort: wetland and abandonedfarmland>plantation and abandoned farmland>plantation and wetland>plantation andfarmland>wetland and farmland>abandoned farmland and farmland in summer. Code Index(species replacement rate index) of size sort: plantation and wetland>abandoned farmland andfarmland>wetland and abandoned farmland>plantation and abandoned farmland>wetland andfarmland>plantation and farmland in summer.(3) Jaccard Index (species similarity index) of size sort: wetland and abandonedfarmland>plantation and wetland>wetland and farmland>plantation and abandoned farmland>abandoned farmland and farmland>plantation and farmland in autumn. Code Index (speciesreplacement rate index) of size sort: plantation and wetland>wetland and abandonedfarmland>wetland and farmland>plantation and abandoned farmland>abandoned farmlandand farmland>plantation and farmland in autumn.(4) Jaccard Index (species similarity index) of size sort: abandoned farmland andfarmland>plantation and wetland>wetland and abandoned farmland>plantation and farmland>plantation and abandoned farmland>wetland and farmland in winter. Code Index (speciesreplacement rate index) of size sort: wetland and farmland>wetland and abandoned farmland>plantation and wetland>plantation and abandoned farmland>plantation and farmland>abandoned farmland and farmland in winter.5. Along "wetlandâ†'plantationâ†'abandoned farmlandâ†'ecotone between wetland andfarmlandâ†'farmland" different environmental gradient dynamics indicates that herb dominantspecies in different seasons exhibit different environment-dependent species flow:(1) Potentilla supina as "wetland-dependent type", Capsella bursa-pastoris and Chenopodium album as "plantation-dependent type", Conyza canadensis as "abandonedfarmland–dependent type", Calystegia hederacea and Descurainia sophia as "farmland-dependent" in spring;(2) P. supina as "wetland-dependent type", C. canadensis as "plantation-dependent type",Diplachne fusca as "abandoned farmland-dependent type", Setaria glauca as "farmland-dependent" in summer;(3) Phragmites australis as "wetland-dependent type", C.serotinum as "ecotone betweenwetland and farmland-dependent type", S. glauca as "farmland-dependent type", Digitariaischaemum as "plantation-dependent type" and "abandoned farmland-dependent type" and"farmland-dependent" in autumn;(4) P.sophia and Ranunculus sceleratus as "wetland-dependent type", D. ischaemum as"plantation-dependent type", Cynodon dactylon as "abandoned farmland-dependent type", D.sophia as "farmland-dependent type", C.bonariensis as "plantation-dependent type" and"ecotone between wetland and farmland-dependent type" in winter.6. In the same ecosystem of various landscape types and in the different ecosystem ofvarious landscape types along environment (longitude, elevation and disturbance) gradientchanges of mountain, hills, and plain, the importance value of herb dominant species presentscontinuous change. Moreover, in the same type of ecosystem of the same landscape types(along different environment gradient changes of outside boundary, inside boundary andcenter), the importance values of herb dominant species present continuous changes amongdifferent ecosystems of the same landscape type along environment gradient changes, theimportance value of herb dominant species shows continuous change.