Abstract:

After Long years sited experiment,recovery and reconstruction system of close,improvement and solid collocation are put forward against the worsen degradation.The experiment show that after 3～5 years of close,the main community biomass of S.bungeana and T.mongolicus increased 5.1～7.5 times than that of the unclosed,after reasonable close duration of S.grandis,i.e.,5 years,the biomass increased by 1.5～5.0 times.The fitted combinations of improved grassland in barren hill by bunch planting are S.bungeana+forb,L.davurica+S.bungeana,biomass increased 6.1～6.4 times than than of the unimproved.Ditch planting in wasteland of S.bungeana+A.frigida, S.bungeana+O.viciaefolia,S.bungeana+L.davurica,its biomass increased 4.6～4.8 times than that of the implanted.Ploughed planting of every two strip in barren hills are A.splendens,S.bungeana+M.sativa,S.bungeana+E.sibiricus+L.davurica,the biomass increased 4.5～6.5times than that of the implanted.Shrub-grass solid collocation,which are Caragana korshinskii+A.splendens+H.hamnoicle+M.suaveolens and P.davidiana+A.splendens,have formed stable renewable communities.The experiment,demonstration and popularization provide the quick recovery of shrub-grass in semi-arid region of Loess Plateau with scientific foundation.

Key words: Loess plateau, Semi-arid region, Degraded grassland, Recovery and reconstruction