Redai dili (Apr 2024)
Litter Accumulation and Water Retention Characteristics of Different Stands of Tropical Rainforest in Hainan
Abstract
As the final layer for precipitation interception in forests, the litter layer is crucial to the vertical structure of forest ecosystems, situated between the forest vegetation and soil layers. Exploring the litter accumulation and water retention characteristics in different tropical rainforest stands is essential for assessing their water conservation functions. This study focused on three forest stands (primary forest, secondary forest, and rubber plantation) within Qixianling Hot Springs National Forest Park in Hainan, China. The immersion method was used to measure litter accumulation and water retention characteristics, exploring variations among these forest stands. Results revealed (1) significant differences in litter accumulation among the stands, with the primary forest having the highest litter accumulation (2.791 t/hm2), followed by the secondary forest (2.077 t/hm2) and rubber plantation (1.660 t/hm2). Litter moisture content followed the order: primary forest (57.57%) > secondary forest (48.33%) > rubber plantation (46.44%). (2) Regarding water retention and water retention rate, both primary and secondary forests showed an increasing trend with immersion time, with the primary forest exhibiting higher water retention and retention rates than the secondary forest. In contrast, rubber plantations showed no clear trends in water retention or retention rates over time. The relation between litter water absorption rate and immersion time followed a well-fitted power function. The maximum water retention capacities were in the order of primary forest (8.041 t/hm2) > secondary forest (6.251 t/hm2) > rubber plantation (4.896 t/hm2). (3) In terms of water absorption and water loss rates, the rubber plantation had the highest water loss rate, followed by the secondary forest and the primary forest. The maximum water loss was observed in the primary forest (5.225 t/hm2) > secondary forest (4.626 t/hm2) > rubber plantation (4.079 t/hm2), and the maximum water loss rates followed the order: rubber plantation (246.319%) > secondary forest (222.649%) > primary forest (189.748%). The forest litter layer's water retention capacity and storage are closely related, with larger litter reserves correlating with greater water retention. Therefore, among the three forest types, the maximum and effective water interception capacities exhibited the following trend: primary forest > secondary forest > rubber plantation. The maximum and effective interception rates show the pattern: primary forests ≈ rubber plantations > secondary forests. The water conservation function of litter is reflected in its water retention capacity and rate of water loss. Given that primary forests exhibit a higher water retention capacity and lower water loss rates, litter accumulation in primary forests is more conducive to forest water conservation functions. Hence, future efforts should focus on protecting litter from primary forests. Conversely, the litter in rubber plantations tends to have a higher rate of water loss, resulting in poorer water conservation. Therefore, future considerations should include planting understory vegetation in rubber plantations to enhance litter water-conservation capabilities and prevent soil erosion. These findings provide crucial theoretical guidance for forest management and the enhancement of water conservation in tropical regions.
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