Hou Dongjie, He Weiming, Liu Changcheng, Qiao Xianguo, Guo Ke
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany Chinese Academy of Sciences Beijing China.
University of Chinese Academy of Sciences Beijing China.
Ecol Evol. 2019 Jul 23;9(16):9214-9224. doi: 10.1002/ece3.5469. eCollection 2019 Aug.
Fencing is an effective and practical method for restoring degraded grasslands in northern China. However, little is known about the role of excess litter accumulation due to long-term fencing in regulating abiotic environment and driving changes in community structure and function. We conducted a three-year field experiment in two fenced grasslands in Inner Mongolia, and monitored light quantity, soil temperature, and soil moisture continuously, and determined community height, community aboveground net primary productivity (ANPP), and the relative dominance of different plant functional groups. Litter accumulation reduced light quantity and soil temperature but increased soil moisture. The regulating effects of litter accumulation on soil temperature and soil moisture fluctuated temporally and gradually weakened over the growing season. Litter accumulation also altered community vertical structure and function by increasing community height and ANPP. The increase in soil moisture increased the relative dominance of rhizome grasses but suppressed bunch grasses, thereby shifting bunch grass grasslands to rhizome grass grasslands. Our findings provide a potential mechanism for community succession in the context of litter accumulation in fenced grasslands and indicate that the vegetation and ecosystem services of degraded grasslands are improved after appropriate fencing.
围栏封育是中国北方退化草原恢复的一种有效且实用的方法。然而，对于长期围栏封育导致的过多凋落物积累在调节非生物环境以及驱动群落结构和功能变化方面所起的作用，人们了解甚少。我们在内蒙古的两个围栏封育草原上进行了为期三年的田间试验，持续监测光照量、土壤温度和土壤湿度，并测定群落高度、群落地上净初级生产力（ANPP）以及不同植物功能群的相对优势度。凋落物积累降低了光照量和土壤温度，但增加了土壤湿度。凋落物积累对土壤温度和土壤湿度的调节作用随时间波动，且在生长季逐渐减弱。凋落物积累还通过增加群落高度和ANPP改变了群落垂直结构和功能。土壤湿度的增加提高了根茎型禾本科植物的相对优势度，但抑制了丛生禾本科植物，从而使丛生禾本科草原转变为根茎型禾本科草原。我们的研究结果为围栏封育草原中凋落物积累背景下的群落演替提供了一种潜在机制，并表明适度围栏封育后退化草原的植被和生态系统服务得到了改善。
