Effects Of Nitrogen Addition On Bryophytes In Taiyue Mountain Of Shanxi

Bryophytes play an important role in monitoring nitrogen deposition of forest ecosystems. In recent years, increased atmospheric nitrogen deposition has became a big threat to the survival of bryophytes. Thus, the response of bryophytes to nitrogen deposition is becoming the focus of attention. A simulated N addition (CK,0 kg/ha/yr, LN,50 kg/ha/yr, MN,100 kg/ha/yr, HN,150 kg/ha/yr) experiment was designed in order to assess the effects of nitrogen deposition on bryophytes. We investigated the changes, coverage of bryophyte species and measured the biomass, C, N, P, chlorophyll content of bryophytes tissues to analyze the biodiversity, productivity and physiological biochemical characteristics of bryophytes,The results showed that:(1)the composition of bryophyte species changed a lot with increasing N concentration. The species of bryophytes were most abundant in low and moderate concentrations of nitrogen. The trends of richness and diversity in different N treatments were different. At the high N level, the abundance of bryophytes decreased and part of the area has changed yellow. This showed that with the increasing concentration of nitrogen deposition, the richness of bryophytes will decline and some species of bryophytes will be on the verge of death and extinction.(2) the biomass of bryophytes in pine forest of Taiyue Moutain was significantly influenced by artificial simulated nitrogen addition. With the increase of nitrogen concentration, total biomass and biomass of green bryophyte tissues increased at low and moderate nitrogen addition levels, then decreased at the high (100 kg/ha/yr) N addition level. The biomass of inactivated yellow bryophyte tissues was gradually increased with the increase of nitrogen concentration and reached the maximum value in the high concentration of nitrogen.(3) nitrogen addition had a big influence on the growth of the dominant bryophyte species. It has significantly affected C, N and P contents of Barbula constricta Mitt.and Marchantia polymorpha L. N concentration of both bryophyte tissues were positively correlated with the levels of nitrogen addition. The concentrations of P and C in bryophyte tissues of Barbula constricta Mitt.increased significantly with the increase of nitrogen concentration. While the response curves of two elements were substantially similar. Meanwhile, the concentrations of P, C in the tissues of Marchantia polymorpha L. showed a downward trend as the levels of nitrogen addition increased.(4) simulated nitrogen addition had influenced chlorophyll, chlorophyll a and chlorophyll b content of both bryophyte tissues. Chlorophyll content, chlorophyll a and chlorophyll b content of Barbula constricta Mitt.tissues were significantly effected by nitrogen deposition. The trends of three pigment contents were substantially the same and reached the maximum at the moderate N level. While the pigment contents of Marchantia polymorpha L. decreased with the increase of nitrogen concentration.