风速及刈割对草原土壤水分与生产力的影响

Impacts of Wind Speed and Mowing on Soil Moisture and Productivity in Steppe

由于全球气候变化与人类干扰的共同影响,全球范围内出现了不同程度的风速下降的现象。试验在内蒙古半干旱草原利用挡风板模拟风速降低,采用不同程度刈割模拟草原利用强度的变化,实地监测近地表土壤水分吞吐量以及群落再生能力的变化。结果表明:挡风板能够有效地降低风速;风速下降在一定程度有助于抑制土壤水分的蒸发损失,提高刈割处理后植物的再生能力。风速降低对内蒙古半干旱草原生态系统综合表现为正效应。加入刈割处理后,风速降低在一定程度上缓解了刈割对草原生态系统的干旱胁迫,但风速降低未能改变刈割处理的影响。

As a result of combined impact of global climate change and anthropogenic disturbance, global wind speed has been found to decrease to different extent. The decrease of the wind speed increases the surface boundary layer thickness, reduces the heat and moisture exchange rate, changes the near-surface micro climate, and reduces the wind erosion, which affects plant growth and other ecosystem processes. The climate characteristic is strong wind, little rainfall, high evaporation and strong solar radiation in Inner Mongolia grassland. Because of the unrea- sonable land utilization way such as overgrazing and farming all throughout the year, Inner Mongolia grasslan system has strong sensitivity of natural and human disturbance. In this study, we simulated reduced wind with wind deflector installed in semi-arid grassland, simulated ent mowing intensity, and monitored variation of near surface eration. The result showed that the wind deflector could red grassland utilization intensity variation through soil moisture input and output and community uce wind speed effectively; the reduced wind d eco- speed differ- regen- speed could contribute to restrain the soil moisture evaporation loss, improve the regeneration capacity after the mowing conduction; so wind speed reduction manifested positive effect on semi-arid grassland ecosystem in Inner Mongolia. Combined with mowing conduction, wind speed reduction could relieve the drought stress of mowing on grassland e- cosystem to certain extent, but wind speed reduction could not change the impact of mowing conduction.