小五台山典型林分枯落物持水恢复能力研究

枯落物层作为森林生态系统的独特层次,截留吸持降水的能力称为枯落物持水能力。降水结束后枯落物暂持水分继续蒸发、下渗,用以调节大气及土壤中的水分以便于下次持水,因此枯落物水分蒸发、下渗的过程亦是其持水能力恢复的过程。以小五台山7种典型林分为研究对象,通过结合野外调查采样及较为符合实际情况的枯落物失水试验,对不同林分枯落物持水恢复能力进行综合研究。结果表明:(1)枯落物层持水能力及可持水量均随着时间逐渐恢复。失水试验进行到8 h时,所有林分未分解层枯落物持水能力恢复到80%以上,除桦树林外的其余林分半分解层枯落物持水能力恢复到60%以上。试验经过12 h后各层枯落物持水能力恢复趋势逐渐缓慢。(2) 7种典型林分枯落物未分解、半分解层水分蒸发、下渗过程与持水过程的规律一致,前期蒸发、下渗量较大,后期随着可释放水量的减少而逐渐降低。经拟合蒸发、下渗量与时间符合对数函数关系,蒸发、下渗速率与时间符合幂函数关系。(3)小五台山典型林分枯落物调蓄水分效应总体表现为持水较快,持水后水分蒸发、下渗较慢的特征。通过聚类分析可以将7种典型林分划分为3类调蓄水分功能群。未来在该地区或其他生境相似区域的水源林树种配置中将功能群纳入考虑依据,可以实现发挥枯落物最佳的生态水文功能。

Recovery Characteristics of Water-holding Capacity of Litter in Typical Stands of Xiaowutai Mountain

Forest litter layer, as a unique layer of forest ecosystem, can intercept and absorb precipitation which is called litter water retention capacity. After precipitation, the temporary water of litters will continue to evaporate and infiltrate, adjust the water in the atmosphere and soil to facilitate the next water holding. Seven typical forests of Xiaowutai Mountain were taken as research objects, through combining field investigation and sampling and litter dehydration test which was more in line with the actual situation, the restoration characteristics of litter water holding capacity of different forests were comprehensively studied. The results showed that:(1) The water-holding capacity of litter layer gradually recovered with time. When the water loss test was carried out for 8 hours, the water holding capacity of the non-decomposed litter layer of all stands was restored to over 80%, and the water holding capacity of the litter in the semi-decomposed layer of the rest stands except pure forest of Betula was restored to over 60%. After 12 hours, the recovery trend of water-holding capacity of litter in each layer was gradually slow. (2) The laws of the non-decomposed, semi-decomposition litter layer water evaporation, infiltration and water holding process of seven typical stands were the same. The amount of evaporation and infiltration was larger in the early stage, and gradually decreased with the decrease of the amount of released water in the later stage. After fitting, the evaporation and infiltration amount were in logarithmic function relation with time, while the evaporation and infiltration rate were in power function relation with time.(3) Litter regulation and water storage effect of typical stands in Xiaowutai Mountain was generally characterized by the faster water retention and slower water evaporation and infiltration after water retention. Through cluster analysis, seven typical stands could be divided into three types of functional groups for regulating and storing water. In the future, functional groups should be taken into account in the tree species allocation of water source forests in this area or other similar habitats, which could realize the best ecological and hydrological functions of litter.