冀西北地区不同生态系统枯落物的水文效应

Hydrological Effects of Litters in Different Ecosystems in Northwestern Hebei Province

[目的]揭示不同植被生态系统枯落物水文效应的差异,为张家口地区生态空间格局优化提供支撑。[方法]基于样地调查和统计分析方法,分别对冀西北地区张家口市森林、农田和草地3种生态系统的枯落物在生长季末期持水能力及其与生物量之间的关系进行分析。[结果]①森林生态系统枯落物的最大持水量(30.7t/hm^2)、有效拦蓄量(22.97t/hm^2)、有效拦蓄率(187.49%)和吸水速率(5.84g/h)4个指标均优于其他两类生态系统。②草地枯落物的各项水文指标均值皆高于农田,最大持水率甚至高于森林生态系统。③枯落物生物量与其最大持水量和有效拦蓄量呈显著正相关关系,而枯落物占生态系统总生物量的比例随总生物量增加呈幂数下降。[结论]如果造林营林方式正确,森林生态系统能够提升区域水源涵养水平,同时草地的水源涵养能力不容忽视,市域内大范围的耕地向草地扩展,将直接影响区域的水源涵养能力。以生物量表征的生态系统固碳能力与枯落物蓄水所反映的水源涵养能力之间的响应关系在生态系统不同尺度下具有不同的表现,在对区域生态空间格局进行优化时,需明确特定环境下不同生态系统类型枯落物的水源涵养能力及其变化对其他生态服务功能的影响,从而实现各生态系统平衡发展。

[Objective]The differences in hydrological effects of litters in different vegetation ecosystems were investigated to provide support for the optimization of the ecological spatial pattern in Zhangjiakou region.[Methods]Based on field investigation and statistical analysis,the water-holding capacities of litters at the end of the growing season of three ecosystems(forests,farmland,and grassland)in Zhangjiakou region and its relationship to ecosystem biomass were analyzed.[Results]①The maximum water-holding capacity(30.7 t/hm^2),effective storage capacity(22.97 t/hm^2),effective interception rate(187.49%),and water absorption rate(5.84 g/h)of forest ecosystem were superior to those of the other two types of ecosystems.②The hydrological indicators of grassland were better than those of farmland.Its maximum water-holding capacity was higher than that of forests.③There was a significant positive correlation between litter biomass and its maximum water-holding capacity and effective storage capacity,whereas the proportion of litter in the total ecosystem biomass decreased with the increase in total biomass.[Conclusion]On condition that the afforestation method is appropriate,forest ecosystems could improve regional water conservation levels.Simultaneously,the water conservation capacity of grassland should not be ignored.The large-scale expansion of cultivated land in the city to grassland would directly affect the water conservation capacity of the region.In addition,the response relationship between the carbon sequestration capacity characterized by biomass and the water conservation capacity reflected by the litter storage had different performances at different scales of the ecosystem.When optimizing the regional ecological spatial pattern,it was necessary to clarify the water conservation capacity of litters in different ecosystem types at a specific scale,as well as its response to other ecological service functions,to achieve balanced development of each ecosystem.