Biomass And Nutrient Distribution And Accumulation Pattern Of Natural Secondaryforests Of Shanxi Province On Loess Plateau

Based on the method of tally stem analysis and chemical analysis on sample plots, the biomass, nutrient contents, nutrient distribution and accumulation and cycling of natural Secondaryforests in Jixian County of Shanxi Province are studied. The biomass of arbor layer were investigated with "average biomass method", shrub layer and herb layer were "harvest method",in the meanwhile discussion on spatial distribution of different organs in different layers.The results show that the biomass is about 36.087t·hm-2, and the distributing sequence is arbor layer>shrub layer>herb layer>litter layer ,The net productivity is 7.2822 t·hm-2·a-1, and the capacity of growth sequence is herb layer> arbor layer>shrub layer. In litter layer, the content sequence of macroelement is K>N>Ca>P>Mg, in arbor layer, shrub layer and herb layer is Ca>N>K>Mg>P,The contents equence of eight microelement is Fe>Mn>Zn>B>Cu>Pb>Ni>Cd in arbor layer,shrub layer and litter layer,Fe>Mn>B>Zn >Cu>Pb>Ni>Cd in herb layer.The capacity of different layers accumulats soil nutrients is diferent.The total trend of the macroelement in arbor, shrub and herb layers is N>P>Ca>K>Mg,the microelement is Cd>B>Zn>Cu> Mn>Ni>Pb>Fe in tree layer, Cd>B>Zn>Mn>Cu>Ni>Pb>Fe in shrub layer, Cd>B>Mn>Zn>Cu>Ni>Pb> Fe in herb layer.The total accumulation of macroelement and microelement is 1111.56 kg·hm^-2 and 29287.43 g?hm-2 spectively,in which the macroelement sequence is arbor layer> shrub layer>litter layer>herb layer and microelement is herb layer>arbor layer>shrub layer>litter layer.The accumulation of macroelement and microelement in arbor layer is 444.79kg·hm^-2 and 7740.84g·hm^-2 spectively . The accumulation of macroelement and microelement in shrub layer is 340.85kg·hm^-2 and 7143.24g·hm^-2 spectively.The distributing accumulated microelement sequence is Fe>Mn>Zn>B>Cu>Pb>Ni>Cd.The accumulation of macroelement and microelement in herb layer is 136.78 kg·hm^-2 and 9979.70 g·hm^-2 spectively, in litter layer is 189.346 kg·hm^-2 and 4423.65 g·hm^-2 spectively,in soil (0-60cm) is 403.067 t·hm^-2 and 159.575t·hm^-2 spectively.The total retention, net accumulation and returns of macroelement is 99.054 kg·hm^-2·a^-1,49.155 kg·hm^-2·a^-1and 49.899 kg·hm^-2·a^-1,microelement is117.35g·hm^-2·a^-1,50.96g·hm^-2·a^-1 and 66.39g·hm^-2·a^-1. The nutrient uptake coefficient of macroelement and microelement stand stood in the order of N>P>K>Ca>Mg and Cd>B>Zn>Cu>Mn>Pb,Ni>Fe, cycling coefficient is K>P>N>Mg>Ca and Fe>Ni>B>Mn>Pb>Cd>Cu>Zn.