Change Of Soil PH And Nutrient Content Of Larch Plantation In The Northern Hebei Mountainous

Larix principis-rupprechtii Mayr is the main afforestation species in north mountain of Hebei, Larch plantation play an important role in timber production, wind prevention and sand fixation, soil and water conservation etc. Soil properties had impacts on timber production and operating conditions. Some studies have found that there is a decline in soil fertility, and soil acidification is also a serious problem. Our study investigated soil chemical properties of different stand age of Larch plantation and Birch natural forest in north mountain of Hebei. Ther is a closely relationship between litter decomposition and soil properties. The study investigated the impact of some local plant litter decomposition on soil properties. We can draw the following conclusions:(1) The soil p H value of woodland is lower than that of bare land, soil cation exchange capacity, base saturation, the content of soil organic matter, available N, available P, total N, total K of woodland is higher than that of bare land, the content of soil total P of woodland is a litter higher than that of bare land, there is no big difference between woodland and bare land in the content of soil available K.(2) The content of soil available P, total N and total K of Larch plantation is lower than that of Birch natural forest, there is not a big difference between Larch plantation and Birch natural forest, the content of soil available N in 10 years and 20 years Birch natural forest is higher than the same stand age of larch plantation, the content of soil available K in 10 years Birch natural forest is higher than the same stand age of larch plantation, there is not a big difference between larch plantation and birch natural forest in other index.(3) The soil in Saihanba is slightly acidic, the soil p H value is between 6.00 and 6.58; the soil p H value of larch plantation is higer than that of birch natural forest; with the increase of stand age, the soil p H value was reduced; with the depeen of soil depth, the soil p H value was rised; with the depeen of soil depth, the soil cation exchange capacity was reduced, the change of soil cation exchange capacity has no obvious relationship with the stand age; the change of soil base saturation has no obvious relationship with the stand age and soil depth. There is a trend of soil acidification in Saihanba, so we shoud take some effective measures to prevent.(4) With the increase of stand age, the content of soil organic matter of larch plantation was first increased and then decreased, the content of soil available N, available P and total N of larch plantation was increased, the content of soil total K and available K of larch plantation was decreased, the content of soil total P of larch plantation has no obvious change; the content of soil organic matter, available N, available P, total N and total P of birch natural forest has no obvious change, the content of soil available K and total K of birch natural forest was decreased.(5) The soil fercility of this area is in middle level, but the content of N and P is poverty. So, we should attention.(6) Compared with first rotation, the soil p H value of second rotation decreased by 0.23, the soil cation exchange capacity, base saturation, organic matter content, available N content, available K, total N, total P and total K content of second rotation had respectively reduced by 44.43%, 9.59%, 24.14%, 20.27%, 28.88%, 28.57%, 9.09% and 16.76%, soil available P content of second rotation increased by 8.09%. It was concluded that there is a variation trend of soil fercility fading in larch plantation in this area, the soil fertility of second rotation showed a downward trend, though it is in a middle level nowtime. Therefore, we should take some appropriate measures to prevent in the process of forest management.(7) The decomposition of herb and shrub litters has a great impact on soil chemical property, while decomposition of coniferous litter has a small impact on soil chemical property. Eluviation of precipitation has little influence on the release of plant nutrient.