毛苔草植被对沼泽湿地蒸散发影响的试验研究

Influence of Deyeuxia angustifolia vegetation on the Evapotranspiration of Mire in the Sanjiang Plain

为了揭示毛苔草植被对沼泽湿地蒸散发的影响,采用野外蒸发桶观测的方法,2007年7月5日至8月8日,在三江平原对不同植物密度下的毛苔草(Carex lasiocarpa)沼泽湿地下垫面蒸散发进行了试验研究。结果表明,毛苔草植被的存在能够增加沼泽湿地下垫面的蒸散发;与野外植物密度相同的有植物桶的蒸散发量平均达到13.88mm/d,最大蒸散发量可达22.26mm/d,而无植物桶的蒸散发量平均仅为4.81mm/d;有植物桶的平均蒸散发量为无植物桶蒸散发量的2.9倍。毛苔草植物的密度越大,对沼泽湿地下垫面蒸散发增加的作用越大,但只有当毛苔草叶面积指数大于1.5时,下垫面的蒸散发量才会显著增加。太阳辐射和气象要素对毛苔草沼泽湿地蒸散发的影响与植物密度间的关系复杂,还需要进一步研究。

For the sake of understanding the influence of Carex lasiocarpa vegetation on the evapotranspiration of mire, field experiments were carried out with evaporation pans in the test field of the Ecological Experiment Station of Mire-wetland in the Sanjiang Plain from the 5 July to 8 August 2007. 10 evaporation pans were installed with different density of Carex lasiocarpa vegetation, and the density was designed to increase with the pan numbers from no. 0 to no. 10. The design that pans no. 0 and no. 1 were set with no vegetation while no. 2 to no. 10 with different density of Carex lasiocarpa was to explore whether Carex lasiocarpa vegetation could enhance the mire evapotranspiration compared with water surface. By the field observation last for 35 days, the conclusions showed that the mire with Carex lasiocarpa vegetation had the larger evapotranspiration than that of the water with no vegetation. Under the condition of the same density to natural Carex lasioearpa community, the pan evapotranspiration with Carex lasiocarpa vegetation was 13.88 mm/d averagely, and the maximum reached 22.26 mm/d, while the pan evapotranspiration with no vegetation was only 4.81 mm/d averagely. So the Carex lasiocarpa community could promote pan evapotranspiratoin. Furthermore, the larger the Carex lasiocarpa community density was, the more its promotion on the evapotranpiration did. The total evapotranspiration experienced growing up of ＂J＂ curve with the leaf area index （LAI） of Carex lasiocarpa. But the Carex lasiocarpa community with low density had limited action on the evapotranspiration and only that with high density could result in remarkable promotion. The high transpiration potential and low energy threshold of vapour transport in Carex lasiocarpa vegetation were the inherent reason. The influences from the radiation and meteorological elements were also noticeable, and their relationships with mire vegetation related to evapotranspiration were complicated, which needs further research.