Study On Plant Species Diversity Of Different Period In Used Panax Ginseng Land Under Converting Cropland To Forestland Conditions

By using the methods of substituting space series for time series, compareto natural mixed forest(sample Ⅴ), setting samples, abandoned3years oldPanax ginseng (sampleⅠ), restored5years (sample Ⅱ),9years (sample Ⅲ)and15years (sample Ⅳ) used Panax ginseng plantation of a total of five typesof samples. Five point sampling set samples of summer plant communities.Random sampling method to set samples of the early spring period the plantcommunity. Survyed community structure and composition, and calculatedspecies important value. We analyzed community species diversity by usingspecies richness index, dominance index, diversity index and evenness index.We analyze total species of community vegetation by β diversity index in thedifferent period of restoration in summer and early-spring period.The results were as follow: shrub layer species richness of natural mixedforest is largest in summer vegetation, herb layer species richness of sampleⅣislargest. The species richness of herb layer＞shrub layer, the composition of herblayer species is rich, while sample Ⅴ natural mixed forest changed in adverse.Shannon-Wienner index,herb layer＞shrub layer from plotⅠto sample Ⅳ4samples, while sample Ⅴnatural mixed forest changed in adverse. Natural mixed forest contained more shrub species. Evenness index, shrub layer＞herblayer, shrub layer vegetation were distributed evenly than herb layer. Dominanceindex, herb layer＞shrub layer. Summer vegetation recovery, herb layer＞shrublayer, while sample Ⅴ natural mixed forest changed in adverse. β diversityanalysis showed that5samples had differences among species composition inshrub layer and herb layer, similarity variation between shrub layer and herblayer was similar.Species richness of herb layer vegetation in eayly-spring period was lessthan summer’s, while sample Ⅴ natural mixed forest changed in adverse. Thelargest species important value of the early-spring plants was natural mixedforest among5samples. β diversity analysis showed that species composition ofherb layer vegetation of had differences between plantations and natural mixedforest. The degree of early-spring plants recovery can be used as standard ofcommunity recovery.