Effect Of Different Fostering Intensity On Current In Daxing’an Mountains Timber

In 1980’s,DaXing’an Mountains provided lots of timber for economics and was destroyed by the fire.In present,the standing grow badly and the ecological function increased.We take the Daxing’anling timber forests(deciduous needle leaf forest) as the research object.The plot was set in Xinlin Forestry 106,107,108,109 block.We set 20 plots of different fostering intensity According to the fostering intensity, we remove the poor stand,brush and replanting seedlings. By using SEBA water quality probes, we measured the 7 indicators of water quality. The litter was collected in every plot,and the taken to measure its water holding capacity in indoor determination. The soil nutrient using the national standard method for the determination of soil nutrient content. According to the value, we analyzed the changes of every index with fostering intensity, and compared with CK. We set an comprehensive evaluating system includes water quality,litter and soil nutrients by grey correlation analysis.(1) This paper makes a comprehensive evaluation of 7 indicators of water quality. In the comprehensive evaluation of water quality,we use variation coefficient on calculating weights of water quality index, get the weights:total suspended solids> turbidity> conductivity> salt > redox potential> temperature >pH. Analysis to establish a comprehensive evaluation model of water quality by using gray correlation, get the following conclusion:moderate fostering intensity benefits the improvement of water quality improvement. When the thinning intensity was 40.01%, the water quality was the best, followed by 34.38% plots and 25.48% plots. With fostering intensity increasing, the comprehensive evaluation value increased gradually, reached 40.10%, the evaluation value reached the highest, and then began to decline.(2) The water holding capacity of litter was analyzed. When the thinning intensity was 13.74%, the amount of litter was maximum (4.951 t·hm-2). When the tending intensity is 40.01%, the modified interception of undecomposed litter is highest(51.162 t·hm-2). In 20.86%, the volume of the half-decomposed litter reaches the maximum(2.792 t·hm-2). The effective retaining content of half decomposed litter reached the maximum in 27.85%. The tending intensity is 27.85%, the litter total effective interception amount is highest.In 13.74%, litter amount get the maximum. The volume of half-decomposition litter reached the maximum (2.792 t·hm-2) at 20.86%.The effective retaining content of undecomposed litter reached the maximum in 27.85% (57.740t·hm-2). When the fostering intensity was 13.74%, the total amount of litter was the largest (27.176 t·hm-2). At this time, storage capacity of the litter is the highest. When the fostering intensity is 27.85%, the litter total effective interception was the highest (100.507t·hm-2).The capacity of resisting flood is best.(3) The content of dissolved N in the soil was significantly increased, and the fostering intensity was beneficial to the accumulation of dissolved N. The effective P in soil showed different degrees of decline after fostering. After runoff-erosion, all pH increased to different degree. Overall,7 soil nutrient indexes have different degrees of loss. Fostering restrains the loss of total K.The loss of total K decreased after fostering.(4)We calculated the correlation of the 19 indicators. By using gray correlation analysis method, we established the comprehensive evaluation system of water quality, litter, the loss of soil nutrient,we calculated the 19 index weights by using variation coefficient method. The weight of the top 3 from large to small is soil pH value, the loss of soil organic content, total suspended solids. The total suspended solids in the water quality evaluation system is also the maximum weight value. We get the following conclusions:fostering intensity is 34.38%, the highest value of comprehensive evaluation of hydrological process. Except the 12.52%, 13.74%,16.75%,20.86%,the scores of the plots under 40.10%were higher than the CK plots. Weak fostering intensity can protect and restore the functions of hydrology in forestry ecosystem.In conclusion,27.85%-40.10% is the best fostering intensity to improve the functions of restoring,to purify the water,to manage the forest sustainably.