The Research About The Project Of Farmlands To Forests Ecological Benefit In Pinglu County

The paper mainly talks about the hilly-gully region, Pinglu County. According to statistical data and field investigation, sampling and laboratory analysis of returning farmland to forest, through System Analysis Approach, it researches the ecological benefit of soil erosion, biomass, soil physical and chemical properties and water conservation of the occupied and different patterns of farmland. The results show that:1Since the implementation of returning farmland to forest, climate has been improved as well as vegetation intercepts runoff, and reduces soil erosion obviously. Winds and dry-hot wind days in returning farmland area have decreased more than20days each year than occupied farmland, the air relative humidity has increased by3%, and there is a about40mm increase in annual rainfall. By2012, there has been twice runoff in runoff field of not returning farmland area (contrast area), while no runoff in other areas. Before returning farmland to forest, soil erosion modulus is3000t/km2a., with no surface runoff in woodland returned from farmland, only occupied woodland soil erosion modulus is0.02t/km2a.; This shows that with the growth of trees in the lands converted from farmlands, runoff has decreased significantly, which effectively reduces the water loss and soil erosion.2After returning farmland to forest, forest resources and ecological environment in Pinglu county is improved greatly, the total biomass is more than that of the occupied areas. Trees grow well in the various lands converted from farmlands, particularly like the acacia woods, which have been planted for12years. Among different types of tree species in the lands converted from farmlands, Qiao Guan layer and litter undergrowth biomass is more than that of the occupied areas. Arborvitae has an advantage in biomass as a kind of Qiao Guan layer species, and in herb layer and litter layer, the peach tree is the best.3Since the implementation of returning farmland to forest, soil physical and chemical properties are both improved, there is a big difference in the recovery degree under various types of returning farmland to forest. Compared to farmland as a contrast, total porosity and capillary porosity of different lands converted from farmlands are greater than the occupied areas, and its surface layer is greater than the lower. From0to20cm surface, total porosity and capillary porosity of four kinds of lands converted from farmlands were greater than the compared occupied areas, among of which the surface soil porosity of acacia is the largest, so this shows that the soil macropore basically remains stable; The aAcacia and arborvitae play an important role in the improved soil bulk density effect. Humus layer content of different lands converted from farmlands is obviously higher than the compared weeds land and farmland, such as the acacia and arborvitae. Arborvitae and wild peach effectively increases the content of soil organic matter. Wild peach has the lowest ph value, improving the efficiency of soil nutrients. The soil available nitrogen and available phosphorus content of different lands converted from farmlands were significantly higher than that of occupied areas, while the available potassium content is relatively slow. For example, the available nitrogen content in the arborvitae is the highest, and the available phosphorus and available potassium content in the Prunus armeniaca shrub are the highest.4The water conservation function of lands converted from farmlands is quite effective. In the various types of returning farmland to forest, water quantity of arborvitae woods and peach is the most significant, proving water storage ability of arborvitae woods is stronger; The high underground water-holding capacity of the acacia and arborvitae shows the rainfall energy dissipation effect is obvious; The water-holding capacity of soil in different types of returning farmland to forest is on average higher than that of the occupied areas, like the highest soil water-holding capacity of the acacia, suggesting that returning farmland to forest has improved soil moisture.