Net nitrogen mineralization and nitrification rates in forest soil in northeastern Taiwan(Environment)

概要

論文の詳細を見る
We used a laboratory incubation approach to measure rates of net N mineralization and nitrification in forest soils from Fu-shan Experimental Forest WS1 in northern Taiwan. Net mineralization rates in the O horizon ranged from 4.0 to 13.8mg N kg^<-1> day^<-1>, and net nitrification rates ranged from 2.2 to 11.6mg N kg^<-1> day^<-1>. For mineral (10-20cm depth) soil, net mineralization ranged from 0.06 to 2.8mg N kg^<-1> day^<-1> and net nitrification rates ranged from 0.02 to 2.8mg N kg^<-1> day^<-1>. We did not find any consistent differences in N mineralization or nitrification rates in soils from the upper and lower part of the watershed. We compared the rates of these processes in three soil horizons (to a soil depth of 30cm) on a single sampling date and found a large decrease in both net N mineralization and nitrification with depth. We estimated that the soil total N pool was 6,909kg N ha^<-1>. The present study demonstrates the importance of the stock of mineral soil N in WS1, mostly organic N, which can be transformed to inorganic N and potentially exported to surface and ground water from this watershed. Additional studies quantifying the rates of soil N cycling, particularly multi-site comparisons within Taiwan and the East Asia-Pacific region, will greatly improve our understanding of regional patterns in nitrogen cycling.