Effect Of Artificial Forest Construction On Plant Diversity In Shanxi Loess Plateau

The research on diversity of cultivated trees is an extent to forest conservation and the return from plantation to forest, which is important for to biological impact evaluation of vegetation recovery.The research, which took place in Xiaxigou area that is located in Shanxi Fangshan County as our study object. After the overall analysis of the area condition and investigation of plant vegetation, 1 kind of non-woodland and 14 kind of cultivated trees varying from the type of growing place, age and configuration were chosen, which are observed in both outside field and inside lab. With the computing method of formula and square error related with biological diversity, some conclusions are drawn as the follows:(1) Xiaxigou basin flora is mainly North Temperate zone distribution. There are 340 kinds of plants which account for 12.7% of Shanxi flora. Although plant diversity is not very rich, it is very special. Its classification group is fairly complicated, and 15 distribution area types of Chinese seed plant have been recorded. Also plant types are relatively rare, but the distribution area type is complicated, which show its partly arid area character.(2)There is 1 new variation: Astragalus discolor var. longipedicellus; 1 modification: Polygala tenuifolia f.alba; supplementing 3 kinds plant "Shanxi flora ": Lespedeza potaninii,Roegneria alashanica,Lotus tenuis; 4 variation: Cynanchum thesioides var. australe,Scorzonera divaricata var. sublilacina,Allium macrostemon var. uratense,Roegneria sinica var. angustifolia; Have Shanxi new precis writer of plant geographical distribution hundred 18 kinds Thesium chinensis,Elymus tangutorum, Salsola collina,Suaeda glauca, Portulaca oleracea, Anemone tomentosa, Halerpestes ruthenica, Thalictrum tenue, Glycyrrhiza uralensis, Lathyrus quinquenervius, Oxytropis bicolor, Trigonella ruthenica, Xanthoceras sorbifolia, Saussurea japonica, Diarthron linifolium, Juncus turczaninowii, Ixeridium gramineum, Viola forrestiana; 3 variation: Aconitum barbatum var. puberulum, Centaurium pulchellum var. altaicum, Saussurea japonica var. alata .These plant species have being bound to contribute to Shanxi flora , are also one of the characteristic that this area is. (All above plant species already has announced equally, all voucher specimen deposition Yu Beijing Forestry University forest plants specimen mansion)(3) Artificial forest which enriched local plant, has changed species structure component, such as the ordering that advantage section belongs to and the inconsistency there being no forest land community, what be contained section , diversity being , growing, some are able to bear overcast plant kind, if speckle leaf violet , green Chinese wolfberry etc. appears then under planted forest, but a few masculine gender seeds of trees, move downwards if foliole mouse Li , lilac do not enter forest then, only not changing the flora type being a river basin's turn to give first place to North Temperate zone.(4) Due to impact by group structure, latitude , slope effect , species density, degree of homogeneity , diversity to factors such as density , age of stand accepting community, concern change between the exponent, the trend is between the community being unlike a type, not consistent. Under other condition is identical situation, density is major factor affects an area community middle species diversity. With standing forest density decrease, irrigation grass tier of species diversity enhances then gradually; But power-up falling, with height in density, standing forest, identical condition of forest, irrigate grass tier diversity trend having then a bit coming down; The main slope behaviour to effect is that overcast slope species diversity is higher than sun slope; The age of stand effect is that age of stand is increasingly high, species diversity is increasingly high mainly.(5) From research data, we can conclude that, under same situation, vegetation species diversity is higher than broad-leaved forest under mingled forest, and broad-leaved forest community plant diversity overtops coniferous forest, indicates that mingled forest and broad-leaved forest are more beneficial for vegetation growth and renewal under forest.