Biocycling of N,P and K of two forest plantations in Miyun County,Beijing
Xiao Yang 1,Chen Lihua 2,Yu Xinxiao 2*
1.College of Agriculture Resources and Environment,Heilongjiang University,150080,Harbin;2.Key Lab.of Soil & Water Conservation and Desertification Combating,Ministry of Education,College of Soil and Water Conservation,Beijing Forestry University,100083,Beijing: China
Abstract��
Characteristics of the rain input,litterfall return,accumulation and nutrient cycling of three primary elements(N��P��K) in Pinus tabuleaefomis forest plantation and the Quercus acutissima and Platycladus orientalis mixed plantation were investigated by means of observing the research stands in the west of Miyun Reservoir of Beijing from 2006 to 2007.The results showed that: 1) annual inputs of nutrient through rain leaching amount to 31.56 and 13.27 kg/(hm 2·a).2) annual returns of N,P and K in P.tabuleaefomis and the mixed plantation through litterfall amount to 18.00 and 31.56 kg/(hm 2·a) respectively.3) the accumulation of N,P and K in tree stratum of P.tabuleaefomis plantation amount up to 612.37 kg/hm 2,and the descending order of the contents of N,P and K in different organs of P.tabulaeformis is leaves,living branches,stems,roots.Accumulations of N,P and K in tree stratum of the mixed plantation amount to 153.87,18.28 and 100.13 kg/hm 2 respectively.4) the descending order of utilization coefficient of nutrient element in P.tabuleaefomis plantation and the mixed plantation is N,K,P and K,N,P;the absorption coefficients of N,P,and K in P.tabuleaefomis is higher than that of the mixed plantation,and the cycling coefficient of N,P,and K in the mixed plantation is higher than that of P.tabuleaefomis plantation.Rain leaching and litterfall return contribute to 63.7%,53.0% and 36.3%,47% of total return in the plantation respectively.Rain leaching return is the main part of total return in the plantation.The annual total absorption of N,P and K is 126.58 and 54.96 kg/(hm 2·a),in which the annual retention is 77.02 and 24.42 kg/(hm 2·a),and the annual return is 49.56 and 30.54 kg/(hm 2·a).
2010, Vol. 8 