The results showed that the basic cultivated farmland (17.59 104 hectares) in the whole city can be divided into 6 grades, among which the IFI (Integrated fertility index) of the cultivated land at the first grade was bigger than 0.85. Its area was 2.07 104 hectares, accounting for 11.8% of total cultivated area.
③ Having analyzed the impact of economic factor with Eviews3.1 software,results are deduced that it needs about new construction land 15.36 hm2 with the occupation of arable land 17.53 hm2,while the city's GDP rises 100million;
Quantitative site classification in the key county in the conversion of farmland to forests project
Carbon and nitrogen concentrations increased significantly with plantation age and had increased by 15.3-20.5-fold and 11.1-13.6-fold at 0-20 cm depth at the 18-year-old plantation compared with farmland soil.
korshinski contributed significant enrichment of C and N contents under their canopies compared with farmland.
The contents of aggregates of over 0.25 mm in two shrub land soils in the upper layer (0-20 cm) increased by 4.6% and 14.1% compared with farmland.
Forest watersheds and farmland watersheds with similar terrain features were selected through cluster analysis to study their runoff and sediment transport characteristics.
The decline of methane oxidizing activities in gray forest soil upon its conversion into arable land was shown to be caused by major changes in biotic and physicochemical properties of soil.
Microbial biomass and the content of microbial carbon in humus (Cmic /Corg) decreased in the following order: soils under forest cenoses-mowed meadow-10-year arable land-46- and 75-year arable land.
The pattern of their vertical distribution in areas with tree and shrub vegetation differs from that in arable land.
Effect of mechanical disturbances on nematode communities in arable land
Measurements showed significantly higher values of saturated hydraulic conductivity for topsoils in wetlands (6.2 m day-1 on average) compared to mown grasslands (1.47 m day-1) and arable land (0.79 m day-1).
Our study indicates that the model can be applied to study the interaction between land surface processes and atmospheric boundary layers over various underlying surfaces and their regional climate effects.
Regularities of wind-erosion of different land-use types in Yongding River sandy land, Beijing
The threshold wind velocity of a number of variables was studied in four different land-use types: farm land, forestland, wild grassland and a flood plain in the Yongding River sandy land in Beijing.
The following conclusions were drawn: 1) The order of decreasing threshold of wind speed for sand displacement and surface roughness were forestland, wild grassland, farm land, sparse wild grassland and flood plain.
At a height of 0-20 cm, the height increased while the sediment discharge percent of sand flux decreased; there were significant differences in the sand flow formation under different land-use types.