自然恢复过程中川西亚高山林草交错带地被物储量及持水性能研究

Ground Cover Reserves and Water Holding Capacity of Forest-grassland Ecotone in Natural Recovery Process in Western Sichuan

以采伐封禁后形成的川西米亚罗亚高山林草交错带为研究对象,分析了自然恢复过程中地被物储量和持水特性的变化规律。试验结果表明：随植被的自然恢复进程,地被物的储量和最大持水量呈逐渐上升趋势,地被物的持水效应增强。枯落物储量占地被物储量的51.48%～76.85%,其最大持水量占地被物层最大持水量的32.4%～61.32%。枯落物层是涵养水源的优势层,但苔藓层在整个地被物层中的水文生态效应也十分显著。苔藓层和枯落物层的最大持水率分别为自身干重的6～7倍和3～4倍,苔藓的最大持水率表现为草甸〈草灌〈灌丛〈次生阔叶林〈针阔混交林〈原始针叶林,枯落物的最大持水率为草甸〈原始针叶林〈草灌〈针阔混交林〈灌丛〈次生阔叶林。地被物的最大持水量和有效拦蓄量随植被的自然恢复显著增加,变化规律为草甸〈草灌〈灌丛〈次生阔叶林〈针阔混交林〈原始针叶林。地被物的吸水速率在前0.5 h最大,随着时间推移吸水速率逐渐降低,到24 h趋近于零。苔藓层的平均吸水速率大于枯落物层,地被物的持水量和吸水速率与浸泡时间的关系可用Q=aln（t）＋b和V=kt^n（R^2〉0.9）进行拟合。采伐干扰后植被的恢复是一个长期过程,森林群落的进展演替能增加苔藓的生物量和枯落物的储量,保护天然林有利于促进现有群落尽快演潜和恢复到该区稳定的顶极群落,对亚高山生态系统水源涵养功能的恢复至关重要。

After deforestation disturbance, the sub-alpine coniferous forest formed forest-grassland ecotone with sequences of meadow, shrub, secondary broad-leaved forest to dark conifer forest in the order of succession. The research analyzed the regularity for change of ground cover reserves and water holding capacity in the natural recovery. The results suggested that ground cover reserves and maximum water holding capacity were in gradual upward trend and the water-holding effect were increased with the process of natural vegetation restoration. Litter reserves were account for 51.48 %-76.85 % in ground cover reserve and the maximal water holding capacity （MWHC, t/hm^2） was 32.4%-61.32% in ground cover MWHC, which showed litter layer be dominant water conservation layer, while the hydro-ecological effects of the moss layer be also very significant. Moss layer and litter layer maximal water holding rate （MWHR, %） were 6-7 times and 3 -4 times of their own dry weight. Moss layer MWHR were in sequences of meadow〈grass-shrub〈shrub〈 secondary broad-leaved forest〈 mixed broadleaf-conifer forest 〈 primitive coniferous forest, litter layer MWHR were in sequences of meadow〈primitive coniferous forest〈grass-shrub〈mixed broadleaf-conifer forest〈shrub〈secondary broad-leaved forest. Ground cover MWHC and the modified interception amount were increased significantly in the natural recovery with the variation of meadow〈grass-shrub〈shrub〈secondary broad-leaved forest 〈 mixed broadleaf-conifer forest 〈 primitive coniferous fores. Water absorption speed of the ground cover in the former 0.5 hour was fastest and gradual slower in the rest of the time. Average water absorption speed of moss layer was greater than litter layer, the equation between the water holing capacity and absorption speed of the ground cover to the immerse time were Q=aln（t）＋b and V=kt^n （R^2 〉0. 9）. The vegetation recovery needs a long-period after logging disturbance, the moss biomass and litter reserves were increased in the progress of the forest communities succession, the results show the protection of natural forests is beneficial to communities succession as soon as possible and return to the climax communities in the sub-alpine region, which is essential to restore the water conservation function of sub-alpine ecosystem.