Accumulation and Biological Cycling of Nutrient Elements in Quercus aquifolioides Shrublands

In natural and man-made protected plantations,cycling of nutrient is an important aspect as significant amounts of nutrients are returned to the soil through litter fall and become available for reabsorption.Nutrient distribution,accumulation and cycling of Quercus aquifolioides shrublands in the eastern slope of the Zheduo mountain were studied.The results showed that:(1)Nutrient concentration differed somewhat according to components.The nutrient elements patterns were NKCaMgP in leaf and branch components and CaKNMgP in stem and belowground components.(2)The total nutrient standing stocks were estimated to be(kg/hm2):N(252.67),P(49.22),K(197.01),Ca(650.06),and Mg(51.18).The proportions of these nutrients distributed in the shrub component,herb component and litter component were 88.61%~96.10%,0.64%~4.22% and 2.54%~9.25%,respectively.(3)Most of the nutrients in Q.aquifolioides shrub were distributed in the belowground components(67%~81%).The abundant nutrient reserve in roots favored for resprouting of Q.aquifolioides after fire and coppicing.(4) The nutrient annual accumulations in the shrubs were[kg/(hm2·a)]:Ca(20.82)N(7.46)K(6.12) P(2.33)Mg(1.55).The nutrient utilization coefficient of the five elements was estimated to be 0.09,and the nutrient cycling coefficient to be 0.60,and the nutrient recycling period was also estimated.The nutrient use efficiency of Q.aquifolioides shrublands was low and the recycling period of nutrient was long.