长期氮素添加对内蒙古典型草原有机碳库的影响

Effects of Long-term Nitrogen Addition on Organic Carbon Storage in Typical Steppe in Inner Mongolia

于内蒙古典型草原地区开展了为期8年的长期氮素添加梯度处理实验来模拟氮沉降,研究草原生态系统地上和地下碳库对氮沉降的响应.结果表明,氮肥添加显著增加了植物活体有机碳库和凋落物碳库,而对根有机碳库的影响并不显著,对0～l0cm、l0～20cm、20～30cm、30～70、0～70cm土层的土壤有机碳含量和土壤碳库也无明显作用.地下部分总碳库和生态系统碳库在试验期内均未随氮沉降量的增大而发生显著改变.

An artificial nitrogen deposition experiments in a typical steppe ecosystem in Inner Mongolia was conducted to study the long-term influences of nitrogen＇addition with different applying rates on the changing trends of different sections of the whole organic carbon pool. The results showed that plant aboveground living organic carbon pool size increased with the elevating rates of nitrogen addition, litter carbon pool size was also enhanced by the gradient increase of nitrogen deposition, though it had some what different responding curve compared with that of plant aboveground living organic carbon pool. Soil organic carbon pool size within the 0~10cm, 10~20cm, 20~30cm, and 30~70cm soil layers were not changed significantly along with the gradient of nitrogen deposition. As a consequence, belowground or- ganic carbon pool and the total ecosystem organic carbon pool were not altered evidently in their size after the eight-year nitrogen addition with various rates.