THE DYNAMICS OF LITTER FALL RESPONSES TO SIMULATE NITROGEN DEPOSITION IN SING-AN LARCH (Larix gmelinii) FOREST
Study of litter fall responses to nitrogen deposition by controlled experiments in Larix gmelinii.Controlled experiments take three nitrogen fertilizer-NH4Cl,KNO3 and NH4NO3-for nitrogen sources and divide to four treatments with low,middle,high nitrogen level and comparison.Through field observations we found:when litter fall of control area from 3 215.67 to 4 748.82 kg ·hm-2,both low and middle nitrogen level achieve hardly significant effect(p < 0.05);through treatments for NH4Cl and KNO3,NH4Cl and NH4NO3,NH4Cl and comparison all reach significant effect withp <0.01 by high nitrogen level.As nitrogen concentration increasing,litter fall is decreasing and is inhibited with NH4 Cl treatment;after KNO3 treatment,the more nitrogen concentration the more litter fall is promoted.Litter fall month show obvious seasonal dynamics and seasonal change presents unimodal type and litter fall peaked is in September.