Trends of Defoliation Decomposition and Nitrogen and Phosphorus Release in River Water

To provide information for understanding nutrient cycling and energy flow in fluvial ecosystems,this paper studied the litter decomposition and elements release dynamics in river water of Dongfeng River in Zhengzhou city,Henan province,using string mesh bag technique. The trail was taken on for 39 days. The results showed that the litter mass had a continuous decreasing pattern and lost 11.6% of the total mass in decomposing process. The trend of dry mass 1oss followed the negative exponential equation. The decomposed time of 95% litter were 8.21 years. The biological and non-biological factors had significant influence on the nitrogen and phosphorus release of the litter. In the first 9 days,nitrogen in the litter lost rapidly,then gradually rise a little,and then,in the last 10 days,lost rapidly again. Meanwhile,the phosphorus in litter showed a fluctuating losing trend during decomposition period:decreased and then increased at the first and medium stage,and decreased again at the late stage. According to the nitrogen accumulation index (NAI) and phosphorus accumulation index (PAI),the nitrogen and phosphorus in litter was mainly released,and had an alternant change characteristics of release-accumulation-release course.