The restoration of the destroyed forest vegetation in Yunmeng Mountain,Beijing

The study was carried out in two sample plots which were set in two regions where the vegetation was protected for 8 and 3 years.The results of DCA (Detrended Correspondence Analysis) showed that the vegetation on the north or northwest aspects in Yunmeng Mountain (Quercus liaotungensis coppice and Spiraea trilobata scrubs) has no systematic floristic difference from the vegetation which existed in the same area in 1964 with the approximate aspect under human disturbance, no matter whether they were protected for 8 or 3 years. In south and southeast slopes (Vitex negundo var. heterophylla community), the protected shrublands have larger species diversities than that of the shrublands in 1964. In addition, there is no significant difference between the communities which were protected for different periods of time. However, the number of species in protected area is larger than that in unprotected area. Furthermore, the community which is under a longer period of protection developes larger diversity. The north slopes have more species than the south slopes.The protection is helpful for communities to develope their biomass. The biomass of scrubs on the north slope is much greater than that on the south in the site where the vegetation is protected for 8 years, as well as in the site under 3 years protection. In contrast, due to the larger coverage of the scrubs on north slopes, the biomass of herbage on the south slope is much greater than that on the north slope in both sites. When compared with the biomass of the shrublands in unprotected area, the increase of biomass shows the efficiency of protection. The aboveground biomass of scrubs in both site are 2.8 and 2.2 times greater than that in unprotected area. The ratio of the total aboveground biomass of Site 1, Site 2 and the unprotected area is 2.5:2.2:1 on south aspect.