| Gonghe Basin of Qinghai province is one of the most serious desertification regions inChina. Vegetation restoration in desertified land is an effective way to control desertificationand improve regional environment. It is also an important way to amelioration and utilizationthe desertified land. Study the effect of vegetation on soil after vegetation restoration canprovide a theoretical basis for better sand-fixing plant species selecting and plantationsustainable managing. This paper was the first time to conduct a comprehensive and systematicstudy on soil properties improved by vegetation in alpine sand land. Systematic study andcomprehensive evaluation was conducted on soil properties improved by different vegetationsat sand dune and lowland between sand dunes in Gonghe Basin. And selected vegetation typeswhich able to well adapt the environment of sand dune and lowland between sand dunes.Secondly, based on the study above, the influence of dune slopes, plantations age andplantations density on soil properties improved by Caragana intermedia Kuang was conducted.The results of this study could provide a theoretical basis and technical support for artificialvegetation construction and vegetation restoration in the alpine sand land. The main results areas follows:(1) The effect of soil improvement for different vegetation types on sand dunesThis study was conducted for better sand-fixing plant species selecting on sand dunes.Soil physical and chemical properties for Artemisia desertorum shrub land, Caraganakorshinskii plantation and Caragana intermedia plantation were determined. The samplingdepth for soil physical properties measure was0-50cm. The sampling depth of soil chemicalproperties measure was0-200cm.4repeats for each species. The results show that soilproperties for3vegetation types on sand dunes have been improved significantly comparedwith the moving sand dunes. All of3vegetation types decreased the sand content in soil,increased the silt and clay content in soil, decreased the soil bulk density, and increased themaximum water holding capacity, capillary water holding capacity, capillary porosity and non-capillary porosity. Soil organic matter, total N, total P and total K conditions for all3vegetation types were also improved. In the3vegetation types, soil texture, soil bulk density,soil organic matter, total N, total P and total K conditions for Caragana intermedia plantationwere better than Caragana korshinskii plantation and Artemisia desertorum shrub land.Maximum water holding capacity, soil water content, soil organic matter, total N, total P andtotal K conditions for Caragana korshinskii plantation were better than Artemisia desertorumshrub land. The soil restoration capability of3vegetation types on sand dunes were alldecreased with greater soil depth. Soil water content firstly decreased and then increased withgreater soil depth, and soil water content in20-100cm depth were lowest for Caraganakorshinskii plantation and Artemisia desertorum shrub land.(2) The effect of soil improvement for different vegetation types in lowland between sanddunesThis study was conducted for better sand-fixing plant species selecting in lowlandbetween sand dunes. Soil physical and chemical properties for Salix psammophila plantation,Tamatix chinensis plantation, Salix cheilophila plantation, Populus simonii and Salixcheilophila mixed plantation and Leymus secalinus grassland were determined. The samplingdepth for soil physical properties measure was0-50cm. The sampling depth of soil chemicalproperties measure was0-200cm.4repeats for each species. The results show that in lowlandbetween sand dunes, the soil texture, soil bulk density, maximum water holding capacity,minimum water holding capacity, capillary water holding capacity, capillary porosity and totalporosity for Salix psammophila plantation, Tamatix chinensis plantation and Leymus secalinusgrassland were better than Salix cheilophila plantation and Populus simonii and Salixcheilophila mixed plantation. Soil water content and total N conditions were also better thanSalix cheilophila plantation and Populus simonii and Salix cheilophila mixed plantation. Thesoil bulk density in0-50cm depth, maximum water holding capacity in10-20cm depth, totalN conditions in20-50cm depth for Salix psammophila plantation were better than Tamatixchinensis plantation and Leymus secalinus grassland. Soil organic matter conditions for Salixpsammophila plantation, Tamatix chinensis plantations were better than other vegetation types. The soil bulk density, maximum water holding capacity, minimum water holding capacity,capillary water holding capacity, total porosity, total N and total P conditions for Salixcheilophila plantation were better than Populus simonii and Salix cheilophila mixed plantation.The soil restoration capability of5vegetation types in lowland between sand dunes were alldecreased with greater soil depth. Soil water content firstly decreased and then increased withgreater soil depth, and soil water content in20-50cm depth were lowest for all of the5vegetation types.(3) The effect of soil improvement for different sand dune slopes of Caragana intermediaplantationsThis study was conducted to determine how soil properties were affected by sand dunesslopes after Caragana intermedia plantation establishment12years on the alpine sandy land ofGonghe Basin on Tibet Plateau. Moving sand dune in the vicinity of experiment site waschosen as a control. Soil samples were collected for four replicates from the depth of0-50cmon windward slopes, dune tops and leeward slopes. The results showed that after establishmentof Caragana intermedia plantations on sand dunes, soil organic matter, total N and total Pconditions for3dune slopes were improved significantly compared with the moving sanddunes. Soil nutrients increased obviously on surface soil. Soil organic matter, total N and totalP conditions were better on windward slopes than dune tops and leeward slopes. More soilorganic matter and total N on surface soil for3dune slopes of Caragana intermediaplantations.(4) The effect of soil improvement for different age of Caragana intermedia plantationsThe objective of this study was to determine how soil conditions on sand dune wereaffected by Caragana intermedia plantations after this shrub grow up. The effects of plantationage on soil water content, soil organic matter content and available nutrition content wereexamined in four ages of Caragana intermedia plantation, e.g.3-,11-,25-, and37-years-old.Soil samples were collected for four replicates from the depth of0-100cm. The results showedthat with the increase of plantation age, soil water condition of Caragana intermedia plantationwas gradually improved, soil organic matter, NH4+-N and NO3--N was gradually increased. However, available P and available K were decreased. The soil water content, soil organicmatter and NO3--N content were decreased with greater soil depth. Soil water condition, soilorganic matter, NH4+-N and NO3--N content was more in the25-year-old Caragana intermediaplantation than other ages of plantations. However, more available P and available K wereconsumed in the25-year-old Caragana intermedia plantation than other three ages ofplantations. The soil water and nutrient conditions were declined in the37-year-old Caraganaintermedia plantation.(5) The effect of soil improvement for different density Caragana intermedia plantationsThis study was conducted to determine how soil physical and chemical properties wereaffected by plantation density. Soil physical and chemical properties for4different densityCaragana intermedia plantations on sand dunes were determined. The sampling depth was0-20cm and4repeats for each density plantation. The results showed that in4differentdensity Caragana intermedia plantations, the soil bulk density, maximum water holdingcapacity, minimum water holding capacity, capillary water holding capacity, soil organicmatter and total N conditions for20000plants per hectares plantation were obviously betterthan13333and2000plants per hectares plantations, and13333and2000plants per hectaresplantations were obviously better than1333plants per hectares plantation. Soil physicalproperties and nutrients conditions for different density Caragana intermedia plantations wereall better on surface soil. |
PDF Full Text Request