Natural Recovery Characteristics Of The Land Used For Engineering Constructionin Vegetations Of The Qinghai-Tibetan Plateau

Linear engineering projects can develop inevitably many Land Used for Engineering Constructions(LUEC)when these engineerings pass through the alpine steppe and alpine meadow in the Qinghai-Tibetan Plateau.The restoration of vegetation and soil nutrients in these LUEC can not only recover the degraded alpine grassland ecosystem,but also improve the security of linear engineering foundation.Previous studies have focused the comparison of restorable plant community with natural plant community.In fact,alpine steppe is distributed on relatively arid regions compared alpine meadow,whether the restoration of vegetation and soil nutrients of LUEC between alpine steppe and alpine meadow is similar is not well documented.This study is to investigate the differences in plant community and soil nutrient of the LUEC in the alpine steppe regions and alpine meadow regions after 24 years in order to provide basic information for revealing the mechanism of grassland resotation of the LUEC and provide decision-making basis for restoration of LUEC in different vegetations.The main results were followings: 1.The height,cover,biomass and evenness index of the restorable plant communities of the LUEC were similar between alpine steppe regions and alpine meadow regions,whereas the plant community diversity index and richness index of the restorable plant communities of the LUEC were different.In both alpine steppe regions and alpine meadow regions,the cover and biomass of restorable plant communities were lower than those of natural plant communities,and the height and evenness index of restorable plant communities were not different between the restorable plant communities and natural plant communities.The diversity index and richness index of the restorable plant communities was bettern in alpine steppe regions than in alpine meadow regions.2.The restorable plant community shared in similar common about the height,biomass,diversity index and richness index of grass functional group,he height,cover,biomass,richness index and evenness index of legume functional group,the cover,diversity index,richness and evenness index of sedge functional group,and the height and cover of forb functional group between alpine steppe regions and alpine meadow regions.The height,biomass,and diversity index of grass functional groups in alpine steppe regions and alpine meadow regions was not different between restorable plant community and natural plant community,whereas richness index of grass functional groups in alpine steppe regions and alpine meadow regions was lower in restorable plant community than in natural plant community.The height,biomass,and evenness index of legume functional group in alpine steppe regions and alpine meadow regions was not different between restorable plant community and natural plant community,whereas the cover and richness index of legume functional groups in alpine steppe regions and alpine meadow regions was lower in restorable plant community than in natural plant community.The diversity index,richness index,and evenness index of sedge functional groups in alpine steppe regions and alpine meadow regions was not different between restorable plant community and natural plant community,whereas the cover of sedge functional groups in alpine steppe regions and alpine meadow regions was lower in restorable plant community than in natural plant community.The height,and cover of forb functional groups in alpine steppe regions and alpine meadow regions was not different between restorable plant community and natural plant community.3.The soil nutrient content of the LUEC was not significantly different between alpine steppe regions and alpine meadow regions.The contents of soil organic carbon,total nitrogen,total phosphorus,total potassium,ammonium nitrogen,nitrate nitrogen,available phosphorus,and available potassium in alpine steppe regions and alpine meadow regions was not different between restorable plant community and natural plant community.4.The restorable degree of plant community and surface soil nutrient at LUEC was bettern in alpien steppe regions than in alpine meadow regions.The retorbale degree about plant community and soil nutrient content in alpine steppe regions was bettern than that in alpine meadow regions,indicating that indicating that LUEC in alpine steppe regions was earier to recover than that in alpine meadow regions.In a word,the height,cover,biomass,evenness index and soil nutrient content of restorable plant communities at the LUEC were similar between alpine steppe regions and alpine meadow regions in the Qinghai-Tibetan Plateau,whereas the diversity index and richness index of restorable plant communities were better in alpine steppe than in alpine meadow.The height,cover,biomass and species diversity of functional groups have similerities and differences between alpine steppe regions and alpine meadow regions.In addition,the restorable degree concerning plant community and soil nutrient content was bettern at LUEC in alpine steppe regions than at LUEC in alpine meadow regions.