赣江源区不同类型低效林水源涵养功能变化特征

Variation characteristics of stand structure and water conservation in different types of low effect coniferous forest transformation in Ganjiangyuan

赣江源水源涵养林是赣江水资源安全的重要生态屏障。为了评价并预测经过改造的低效林和残次林的水源涵养功能及改造后期效果,采用样地比较法在赣江源自然保护区的针叶林和阔叶林内,通过空间代时间的研究方法,以马尾松和木荷的复合林分、杉木阔叶树复合林和阔叶林为参照,作为改造针叶林分在未来时间维度上演替进程中发育形成的目标林分,研究改造针叶林分与参照林分生态功能的差异。结果表明:(1)研究区改造林分林下植被覆盖度和生物量大幅提高,土壤理化性质得以改善。低效林和残次林改造4 a后,林分地上部分生物量和林下灌草的覆盖度得到了较大幅度的提高,分别提高15.67%和33.32%。(2)改造4 a的低效和残次针叶林在改善水质、涵养水源上与演替进程中的参照林分具有较大的差异。改造后的林分可增强水自净能力,提高了地表径流水溶解氧饱和度,增幅为4%~12%。(3)林分结构单一的低效针叶林进行阔叶化改造是重要和必要的。采取合理的方案和技术,可以避免水土流失加剧的情况。

The Ganjiangyuan water conservation forest is the important ecological protective screen to the security of water resource of Ganjiang River.In order to evaluate and predict the water conservation function of the transformed low-efficiency forest.Using the sample plot comparison method and the space for time method,the coniferous forest and broad-leaved forest in Ganjiangyuan Nature Reserve were taken as the reference forests to transform the low-efficiency forest in the short period succession,and compared the ecological functions between the transformed forest and the references forest.It was showed that:(1)After four years’transformation,the above-ground biomass and the coverage of understory shrubs of the low-efficiency coniferous forests have been greatly improved by 15.67%and 33.32%respectively.(2)There are still big difference between the transformed forest and the references forest in the water quality and the water conservation ability after four years’transformation.After transformation,the low-efficiency forest improved the water self cleaning capacity,and increased the dissolved oxygen saturation of the surface runoff water by 4%~12%.(3)With the development and renewal of forest stands,the transformed low-efficiency coniferous forests will exhibit stronger ecological protection functions of reducing surface runoff and soil erosion.The transformation of low-efficiency coniferous forest to broad-leaved forest is important and necessary,and if take rational plan and technique,even worse water and soil erosion are evitable.