滇中高原常绿阔叶林对天然降雨雨滴动能的影响

为探究滇中高原优势群落常绿阔叶林植被对降雨雨滴动能的影响,于2016年和2017年5—9月,在天然降雨条件下运用自计雨量计和滤纸色斑法,通过定位监测磨盘山常绿阔叶林林外降雨和林内穿透雨特征及其雨滴特性,针对不同降雨条件研究了常绿阔叶林对雨滴动能等特征的影响。结果表明:林外的雨滴个数比林内降雨的雨滴个数多61.7%;随着雨量的增大,雨滴直径分布规律也呈逐渐增大的趋势;在小雨条件下,0.5mm林外降雨雨滴直径数量占总雨滴数的40.85%,而同径级雨滴林内仅占总数的12.22%,且以0.5~3.5mm的雨滴数量所占比例较大;当林外降雨雨滴直径超过4.5mm,雨滴终点速度稳定在9.34m/s;林内降雨雨滴直径超过4.1mm,雨滴终点速度稳定在7.05m/s;同一雨滴径级下,暴雨条件下的雨滴动能比小雨时的动能大98.29%,且随降雨量的增大而增大,林内累积雨滴动能的峰值达到林外降雨的20.68%。随着雨滴直径的增大,穿透雨势能、降雨总势能及林冠截留势能均呈逐渐增大的趋势,缓冲势能比穿透雨势能大46.59%,占总势能的65.18%。林冠层对小雨具有截持和增大林内降雨雨滴直径的作用,且造成林内降雨的滞后性,林冠对天然降雨的降雨速度、势能及动能起到明显的缓冲作用。

Effect of Evergreen Broad-leaved Forest on Kinetic Energy of Natural Rainfall Raindrop in Central Yunnan Plateau

Using rain recorder and filter paper stain method, the effects of evergreen broad-leaved forest on raindrop kinetic energy of Mopan Mountainin Yunnan Plateau were explored, during the period from May to Sep in 2016 and 2017. The results showed that the number of raindrops was more than troughfall raindrop by 61.7%. With the increase of rainfall, the raindrop diameter increased gradually. Raindrops with diameter <0.5 mm of outside of forest accounted for 40.85% of total number of raindrop in the light rain condition, while the proportion was only 12.22%, and the number of raindrop with 0.5~3.5 mm diameter accounted for a larger proportion than outside forest. When raindrop diameter >4.5 mm in outside forest, the raindrop terminal velocity stabilized around 9.34 m/s. When raindrop diameter >4.1 mm, the speed was about 7.05 m/s. Rain kinetic energy at the rainstorm condition was larger than it in light rainfall by 98.29%.and with the increase of rainfall, the peak in cumulative raindrop kinetic energy reached 20.68% rainfall outside of the forest. With the increase of raindrop diameter, the throughfall potential energy, total rainfall potential energy and canopy interception potential energy both showed a gradual increase trend. The buffering potential energy was 46.59% larger than that of penetrating rain potential, accounting for 65.18% of the total potential energy. The canopy layer has the function of retention and increase of raindrop, which also cause the rainfall lag in forest, and the had obvious buffering effect on the rainfall speed, potential energy and kinetic energy of natural rainfall.