A Study On The Nitrogen Mineralization Of Forest Ecosystems In Changbai Mountain

Nitrogen is one of the essential element plant needs in the period of growth. In the forest ecology system,nitrogen has important influent on forest community succession. Nitrogen also plays an important role in the maintenance community stable and keeps a certain tree species composition.Soil nitrogen mineralization in different forest type of Changbai Mountain is reaserched in this paer. Sample plots are setted with elevation and forest type in the north slope of Changbai Mountain. Sample plot with elevation from low to high:Ⅰsample plot, broad leaved Korean pine forest , elevation 761m;Ⅱsample plot, Korean pine spruce fir forest , elevation 1258m,Ⅲsample plot, birch spruce fir forest, elevation 1582m.Using correlation equation of temperature and nitrogen mineralization rate, soil temperature of field-survey record is substituted in equation and calculated nitrogen mineralization rate of different forest type. Soil nitrogen-supplying capacities and relationship between nitrogen mineralization rate and environment factors.Main results as follows:1,Soil nitrogen mineralization rate of different forest type on north slope of Changbai Mountain: broad leaved Korean pine forest 0.12kg/(hm2·d), Korean pine spruce fir forest 0.09 kg/(hm2·d), birch spruce fir forest 0.07 kg/(hm2·d). Quantity of the mineralized nitrogen of different forest type: broad leaved Korean pine forest 8.34 t·hm-2·yr-1, Korean pine spruce fir forest 7.22 t·hm-2·yr-1, birch spruce fir forest 6.74 t·hm-2·yr-1.The results showed that nitrogen-supplying capacities of broad leaved Korean pine forest is the strongest.2,The seasonal change of soil nitrogen mineralization rate: nitrogen mineralization rate of three different forest types has evident seasonal variability.3,Changes of nitrogen mineralization rate with elevation: In the same time, nitrogen mineralization rate gradually declines with altitude rising in different forest type.4,The relationship between nitrogen mineralization and air temperature: Relationship equations between the soil nitrogen mineralization rate and air temperature is cubic polynomial and they showed significantly(R2>0.95).