A Study On The Restoration Of The Hydrological Functions In The Second Generation Chinese Fir Plantation

Hui Tong Location Station is located in Hui Tong,Hunan Province,in the upper stream region of Yangtze River.The Chinese Fir Plantation is widly planted:the areas is 24% of the total areas of artificial forest while the accumulation is 28.3% of the total accumulation in China,it has great position in the national economy.So,sutdy on the hydrologic cycle and the waterbalance of the Chinese Fir Plantation with the time and the apace changing, you can not only get accquired the rules of the hydrological cycle and waterbalance,but also get to know the influnences to the hydrological cycle region, evenmore,to the hydrological cycle in the upper stream of Yangtze River.Using the waterbalance in the thesis,the wanterbalnce and the hydrologic functions was studied in a whole water year(2005)in theâ…¢WaterShed of HuiTong location Station.In order to reveal the changing rules of waterbalance and the hydrological fuctions in the second generation Chinese Fir Plantation under the presently manegement pattern,provding theory foundations of persistence progress to the economic and ecological effect of the Chinese Fir Plantation,helping the forest department making policy.The result shows:the precipitation was 1077.50mm in 2005,221.57mm was intercepted by crown,the crown interception rate was 20.56%.The crown interception can decrease the water through the crown,alleviate the influence to siol;it is also form a special microclimate circumstance,which can restrain the evaporation of siol in the woods and keep higher siol moisture.The litterfall is another importance layer of the forest,and the amount of is dymatic.The amount of litterfalls was about 0.9t/ha in 2005.The litterfalls has great capacity for saving water and it is about 2 times of the selfish weght,which equal to 2mm.The litterfalls like a reservior,can reserve a lot of water.The litterfalls provided conversation for soil,decrease and put off the suvice runoff,increase the water percolation,restrain the siol evaporation.The soil is another inportance part of forest also,and it is the mainly place for saving water.The water in the soil changing from 296mm to 415mm in 2005,the changing range is broad.The soil in the forest has great capcity for saving water,and it can decrease the underground runoff in the rainy period while increased the underground runoff in the dried-up period.In the waterbalance of the Chinese Fir Plantation:the input of water was 1077.5mm,comes from precipitation,the output of water including two forms:the output of runoff and the output of evaporation.the tunoff was 191.90mmwhile the evaporation was 899.49mm in 2005,totally 1091.39mm.The water saving in the system was a adjustment factor for the waterbalance,the siolmoisture deficit was 13.89mm, which was 1.29% of the preciptation.The cutting of the first generation Chinese Fir Plantation bringed strongly interference to the land.With the fields hoed and the plantation of the second generation Chinese Fir Plantation,the adjustment of the forest gradually increased,the crown formed,the amount of litterfalls increased,the phsics and hydrological character was impeoved,and the hydrological functions was in restored.The crown interception was in the second generation Chinese Fir Plantation was 40mm less than the crown in the first generation,the crown interception rate was 4% lower;the totally runoff was 191.90mm,which was 20mm less than and 2% lower than the first generation;the evaporation was 33.5mm more than the first generation,the crown interception evaporation decreased 48mm while the other evaporation increased 80mm;the soilmoisture dificit was 13.89mm which was 1mm more than the first generation.But the pattern of waterbalance was changed:the runoff,totally ovaporation,the soilmoisture changing was respectly 17.81%,83.48%,1.29%.The runoff decreased while the evaporation inrceased.it is also means the output of water in liquid decreased while the output of gaseous increased.In order to accelerate the restoration of hydrological functions,suggested changing the manegement mode:transfer the coniferious forest to mix broadleaf-conifer forest to changing the metabelization condition for the litterfalls,accelerate the siol restoration,improve the hydrological functions and the nutrient conditions in the Chinese Fir Plantation ecosystem.