南亚热带喀斯特区原生林和次生林凋落物与土壤水文效应

Study on the Effects of Litter and Soil Hydrology of Karst Forests in the South Subtropical Region

摘要: 本文以广西三十六弄－陇均省级自然保护区原生林和次生林为研究对象，通过野外调查和室内浸泡，探讨原生林和次生林凋落物层和土壤层水文效应。结果表明1) 凋落物厚度和蓄积量均呈原生林 > 次生林，原生林凋落物厚度和蓄积量分别为22.65 mm和7.35 t∙hm⁻²，次生林分别为19.51 mm和6.45 t∙hm⁻²。2) 凋落物最大持水量和有效拦蓄量均表现为原生林 > 次生林。3) 凋落物吸水速率和浸水时间的关系均符合幂函数关系(R² > 0.958, P < 0.01)，持水量与浸水时间的关系均呈明显对数关系(R² > 0.913, P < 0.01)。持水过程中，原生林和次生林凋落物均表现为在浸水1 h内持水量迅速增加，1 h后增加速度变慢，10~12 h后持水量基本不变，24 h吸水速率趋于0。4) 在0~30 cm土层内，土壤容重均值呈现原生林 < 次生林，土壤有效持水量和最大持水量均表现为原生林 > 次生林。5) 原生林林地有效持水量为119.61 t∙hm⁻²，大于次生林105.01 t∙hm⁻²，原生林持水性能较好。综上，石灰岩常绿落叶阔叶混交林具有较强的水源涵养能力，且原生林优于次生林。

Abstract: This research took the primary forest and secondary forest in Guangxi 36 Lane-Longjun Provincial Nature Reserve as the research object, studying the hydrological effects of litter layer and soil layer based on field investigation and indoor immersion methods. The results showed that: 1) The litter thickness and the biomass storage showed primary forest > secondary forest, the litter thickness and biomass storage of primary forest were 22.65mm and 7.35 t∙hm⁻², and secondary forest were 19.51 mm and 6.45 t∙hm⁻², respectively. 2) The maximum water-holding capacity and modified interception amount exhibited primary forest > secondary forest. 3) Litter absorption rate and soaking time was power function relationship (R² > 0.958, P < 0.01), whereas water holding capacity and soaking time had visible logarithmic relationship (R² > 0.913, P < 0.01). In the water- holding process, the litters in primary forest and secondary forest showed that the water-holding capacity increased rapidly within 1 hour of immersion, and the increasing speed slowed down after 1 hour. After 10~12 hours, the litter basically stopped absorbing water, and the absorption rate reached 0 at 24 hour. 4) In the 0~30 cm soil layer, the average soil bulk density showed primary forest < secondary forest, and the soil effective water-holding capacity and maximum water- holding capacity revealed primary forest > secondary forest. 5) The effective water-holding capacity of primary forest was 119.61 t∙hm⁻², which was greater than that of 105.01 t∙hm⁻² in secondary forest, indicating that the water-holding capacity of primary forest was relatively good. In conclusion, the Karst mixed evergreen-deciduous broadleaf forest has a strong water conservation capacity, and the primary forest is better than the secondary forest.