The Characteristics Of Community Ecology Of Plant In Improving Soil Erosion Environment In The Hilly-gullied Loess Plateau

The soil erosion is serious in the hilly-gullied Loess Plateau, and the ecologicalenvironment is fragile. Ecological environment construction must been put in the first sitewhen this area is governed. Vegetation recovery is the core of Ecological environmentconstruction. Vegetation plays an important role in improving ecological environment andpreventing soil erosion. Thus, in this study, community composition structure wasinvestigation and analysis in five erosion environments (sunny gully slope, sunny hilly slope,hilltop, shady hilly slope, shady gully slope) in three vegetation zones (the forest zone, theforest steppe zone, the steppe zone); the accumulation, water holding capacity and thepotential nutrient return of main species’ litter were studied in five erosion environments in atypical small watershed; then the adaption and improvement capacity of plant communitieswere analyzed on the base of them. The main results are as follows:1) There were55families,125genera and165species in three vegetation zones. Almosthalf of the species were Compositae, Leguminoseae, Gramineae and Rosaceae, they taken of40.8and49.1percent of the total number of genera and species. The areal-type wascharacterized mainly by north temperate zone, it taken25.8%and38.4%of the total numberof genera and species. The life form was characterized mainly by hemicryp tophytes, it taken39.1%. The grouth form was characterized mainly by perennial herb, it taken58.4%. Thewater ecological type was characterized mainly by xerophytic, xerophytic-mesophytic andmesophytic, they taken93.3%. The communities were classified into27types. Arborcommunities distributed in the forest zone, shrub communities and semi-shrub, herbaceouscommunities distributed in three vegetation zones. Arboreal community distributed in thegully slope, shrub communities distributed in hilly and gully slope, semi-shrubs andherbaceous communities distributed in hilltop, hilly and gully slope.2) The species richness, Margalef index, Shannon-Wiener index and Pielou indexordered as the forest zone> the forest steppe zone> the steppe zone. The trend of speciesrichness, Margalef index, Shannon-Wiener index and Pielou index was not consistent. Thecoverage was not significant in different erosion environments. The above-ground biomass ordered as the forest zone> the forest steppe zone> the steppe zone, shady slope> sunnyslope> hilltop, hilly slope> gully slope in shady slope, gully slope> hilly slope in sunnyslope.3) The litter amount ordered as the forest zone> the forest steppe zone> the steppe zone,the coverage, thickness and amount of litter were different in different erosion environments,it had relation to the community types, micro-sites, runoff in different erosion environments.The accumulation of litter was shady slope> hilltop> sunny slope. The accumulation of litterin diffrerent micro-sites was significant, under vegetation> ephemeral gully> fish-scale pit>bare land in the sunny slope, ephemeral gully> fish-scale pit> under vegetation> bare landin the shady slope, under vegetation> bare land in the hilltop, fish-scale pit and bare landwere shady slope> sunny slope.4) The maximal water holding capacity of main species’ litter was up to1.22-4.34timesof its dry mass. The maximal water holding capacity of main species’ litter was significant,ordered as defoliation of Bothriochloa ischaemun> defoliation of Artemisia gmelinii>deadwood of Bothriochloa ischaemun> defoliation of Lespedeza davurica> Stipabungeana> deadwood of Lespedeza davurica> deadwood of Artemisia gmelinii. The soilinfiltration capacity was increased by the main species’ litter storage, ordered as defoliation ofBothriochloa ischaemun> defoliation of Artemisia gmelinii> deadwood of Bothriochloaischaemun> defoliation of Lespedeza davurica> Stipa bungeana> deadwood of Lespedezadavurica> deadwood of Artemisia gmelinii.5) The Carbon and Nitrogen content of species were not significant in different erosionenvironments, but they were extremly significant among different species. Impact of litterdecomposition indicators were extremly significant among different species. The lignin andcellulose content, lignin/N ratio were extremly significant in different erosion environments,C/N ratio was not significant in different erosion environments. Combine internal factors andexternal environmental factors on the litter decomposition, the litter of Lespedezadavuricawas stronger than Stipa bungeanaon on improving the soil nutrients, the litter ofBothriochloa ischaemun in sunny slope was small on improving the soil nutrients, the litter ofArtemisia gmelinii was easier to decomposition in the shady gully slope, so it could speculatethat the potential return of Artemisia gmelinii’s litter was greatest. The Artemisia gmeliniicommunity in the shady gully slope was more conducive to increased soil nutrients.6) In different communities, the species richness was between14to37, Margalef indexwas between2.28to6.01, Shannon-Wiener index was between0.50to2.82, Pielou index wasbetween0.17to0.98, the coverage was between20.0%-85.0%, the above-ground biomasswas between73.40g/m~2to35467.34g/m~2, the coverage of litter was between1.19%to 39.50%, the thickness of litter was between0.10cm to2.55cm, the amount of litter wasbetween31.04g/m~2to681.65g/m~2. By comprehensively the indexes for evaluating thecommunity to reduce soil erosion, in forest zone, Quercus liaotungensis-Spiraea pubescens-Carex lanceolata community in shady gully slope and Syringa pekinensis-Ostryopsisdavidiana-Artemisia giraldii-Carex lanceolata community in shady hilly slope couldbasically eliminate soil splash erosion, Acer buergerianum-Syringa pekinensis-Sophoraviciifolia-Carex lanceolata community and Rosa xanthina-Sophora viciifolia-Stipabungeana-Artemisia gmelinii community in sunny slope could migigate soil splash erosion;in forest steppe zone, Artemisia giraldii-Artemisia gmelinii community and Selaginellasanguinolenta community in shady slope were better than Sophora viciifolia-Periplocasepium-Bothriochloa ischaemun-Artemisia gmelinii community and Periploca sepium-Artemisia gmelinii community for migigating soil splash erosion; in steppe zone, Artemisiagmelinii-Dendranthema indicum community in shady slope was better than Caraganaintermedia-Periploca sepium-Artemisia giraldii-Artemisia gmelinii community in sunnygully slope for migigating soil splash erosion.