Study Of The Nutrient Cycling Of Typical Vegetation Community In Hilly Region Of Taihang Mountain

The biomass,productivity and nutrient cycling of Quercus Variabilis,Pla tycladus orientalis and Robinia pseucdoacacia were studied in one year period. The results showed that (1)the biomass of Quercus Variabilis plantation(20 to 40 years old) respectively were 131.65t/hm2, 202.96t/hm2 and 291.15t/hm2. The biomass of Robinia pseucdoacacia and Platycladus orientalis were 39.87 t/hm2 a nd 45.55 t/hm2 Net primary productivity of Quercus Variabilis increased with t he increased of their ages.The maximum net primary productivity in organs wa s bole,the minimum was leaves. The maximum net primary productivity in org ans of Platycladus orientalis and Robinia pseucdoacacia was bole also, the mini mum of Robinia pseucdoacacia was leaves,but minimum of Platycladus orientali s was bark.The annual production of litter respectively of Quercus Variabilis were 6776.19kg/hm2 7531.06kg/hm2 and 8660.26kg/hm2. The annual production of litter respectively of Robinia pseucdoacacia was 5372.34kg/hm2, The annual production of litter respectively of Platycladus orientalis was 5372.34kg/hm2.(2)The total accumulation of nutrient element in Quercus Variabilis(20 to 40 years old) was 2764.58kg/hm2～3689.38 kg/hm2.The range of nutrient accumulation in Quercus Variabilis(20 to 40 years old) plantation were 89.88kg.hm^-2.a^-1 138.17kg.m^-2.a^-1.Return of different element of Quercus Variabilis(20 to 40 years old)plantation were 229.80kg.hm^-2.a^-1,262.06 kg-hm^-2.a^-1 and 246.63kg.m^-2.a^-1. The total accumulation of nutrient element in Robinia pseucdoacacia and Platycladus orientalis were 633.78kg.m^-2.a^-1 and 455.23kg.m^-2.a^-1, The range of nutrient accumulation in Robinia pseucdoacacia and Platycladus orientalis were 36.15 kg-hm^-2.a^-1 and 23.27 kg.m^-2.a^-1, Return of different element of Robinia pseucdoacacia and Platycladus orientalis were 286.52kg.m^-2.a^-1 and 347.12 kg.m^-2.a^-1 .The conservation gross increased with the increased of trees age.The regularity of the absorption,return of different element were accordant and all increased with the increased of trees age,then all reduced.The range of nutrient accumulation reduced with the increased of trees age.The top-down model of the conservation,return of different element and the absorption of different element in Quercus Variabilis(20 to 40 years old) was Ca>N>P.(3)The use coefficient of Quercus Variabilis was reduced with the increased of trees age,cycle coefficient was increased with the increased of trees age,turnaround time was increased with the increased of trees age. In early stage stands, nutrient use eficiency in Quercus Variabilis stands was lower but recycling rate Was higher and turnover period Was shorter. Mature stands had a lower nutrient recycling rate and a longer turnover period, so the trees extract more nutrient elements from soil. Hence measures should be taken to facilitate the successional process to reach a stable zonal community . Recycling rate of Platycladus orientalis and Robinia pseucdoacacia were 0.8 and turnaround time was shorter,result showed that plant nutrient absorption as the return of most of return to the soil, embodies the elements of the high-speed nutrient recycling characteristics.