Simulation Rainfall Experiment of Nitrogen and Phosphorus Loss in Surface Runoff from Bamboo Forest Slopes Land Under Different Managements

ZHANG Li-ping1,ZHANG Rui-bo2,WU Xi-yuan1(1.Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition,Key Laboratory of Polluted Environment Remediation and Ecological Health,Ministry of Education,College of Natural Resources and Environmental Science,Zhejiang University,Hangzhou 310029;2.College of City,Zhejiang University,Hangzhou 310015)

bamboo timber forest;bamboo shoot forest;simulation rainfall;nitrogen and phosphorus loss;concentration;runoff

The management methods of bamboo forest were divided into three types.They were non-till bamboo timber forest(BTF),bamboo shoots forest with once clearing weeds and bamboo subterranean stem for one year(BSF-1) and for two years(BSF-2).The loss processes experiments of total nitrogen(TN) and total phosphorus(TP) were conducted on bamboo forest slope fields under different managements in Lin'an and Anji counties of Zhejiang province in 2008 and 2009.The testing runoff plots were designed with the slope of 20°,the area of 3 m×1.5 m,respectively on the different management bamboo forest slope lands.The experimental method of using rainfall simulator was taken,simulated rainfall intensity of 0.53~1.90 mm/min for 30~60 min from runoff occurring.The process characteristics of nitrogen and phosphorus loss were analyzed on the basis of simulated rainfall of 8 sets.Some conclusions were obtained as following:(1)In the same management ways,the loss amount of TN and TP in surface runoff increased as the rainfall intensity increased.When the rainfall intensity >10.1 mm/min,the increasing speed of TN and TP loss amount were faster,when the rainfall intensity ≤10.1 mm/min,the increasing speed of TN and TP loss amount were slower.(2)Under the same rainfall intensity,the loss amount of TN in surface runoff from BSF plots were 3~7 times as from BTF plots.But the loss amount of TP in surface runoff from BSF plots were less than from BTF plots.(3)On the BSF plots,the loss amount of TP in sediment was very greater with hundredfold increasing than on the BTF plots.(4)In the loss processes of TN and TP in the surface runoff,the concentration of TN and TP acted as important factor in the initial stage,runoff and sediment took the leading part in the later stage.The above results could be provided some scientific basis for bamboo forest management.