机构地区: 中国科学院华南植物园
出 处: 《植物生态学报》 2011年第12期1209-1218,共10页
摘 要: 如何基于常规测定因子评估森林在土壤水分保持方面的生态效益,并建立森林固碳效益与水文效益的联系等科学问题,在综合评估森林生态效益方面有着重要意义。该文以南亚热带地区的3种不同演替阶段的森林生态系统(人工恢复的马尾松针叶林(Pinus massoniana coniferous forest,PF)、马尾松针阔叶混交林(mixed Pinus massoniana-broad-leaved forest,PBF)和季风常绿阔叶林(monsoon evergreen broad-leaved forest,MBF))为研究对象,通过分析其土壤有机质及土壤水分状况在林内及林型间的分布格局差异,探讨土壤有机质对土壤水分保持的控制作用。结果表明:由PF至地带性顶级群落MBF的3种林分虽然相距很近且有关环境因子一致,但0–30 cm土层的土壤含水量差异显著,MBF的最高,PBF其次;3种林型林内土壤水分分布格局迥异,MBF的土壤水分随土层加深而递减的趋势明显,PBF土壤各层水分较为均一,PF则土壤表层水分含量较低,与土壤有机质的状况一致。土壤水分特征曲线显示,0–40 cm土层在相同基质吸力条件下的土壤水分含量:MBF>PBF>PF,MBF的保水性最好。进一步分析发现,土壤孔隙度对土壤含水量的影响最大,饱和含水量、土壤有机质次之,同时,考虑到土壤孔隙度和土壤饱和含水量对土壤有机质的高度依赖性,我们认为土壤有机质控制着土壤含水量及其有效性(p=0.014)。作为常规测定指标的土壤有机质,不仅是森林固碳效益的关键指标,而且可用来量度土壤水分保持及其有效性,可以作为评价森林生态系统服务功能的一个综合指标。 Aims Assessment of the ecological benefits of forest in soil water retention based on conventionally monitored factors and exploration of the relation between forest carbon-sink function and hydrological benefits has special meaning in Millennium Ecosystem Assessment.Our objectives were to 1) characterize the spatial and temporal variations of soil moisture in three subtropical forests and 2) determine the controlling action of soil organic matter on soil moisture retention during vegetation succession.Methods Standard plots were established in Pinus massonniana coniferous forest(PF),mixed Pinus massonniana-broad-leaved forest(PBF) and monsoon evergreen broad-leaved forest(MBF).We measured soil water content every 10 days from 2002 to 2008 using neutron probes and analyzed soil organic matter content in the laboratory by the potassium dichromate oxidation method.Important findings With natural succession from planted PF to climax MBF,soil water content(0–30 cm soil layer) increased significantly;soil water content was highest in MBF and lowest in PBF.The distribution patterns of soil moisture in the three forests were different: the soil moisture of MBF decreased with soil depth,was more homogeneous in the soil profile in PBF and was lower at the surface than in deeper layers in PF.The soil water characteristic curves showed that under the same matrix suction the magnitude of soil water content(0–40 cm soil layer) was: MBF PBF PF;the soil of MBF was the most retentive.Further analysis indicated that soil porosity had the greatest impact on soil moisture,followed by saturated soil water content and soil organic matter content,while soil bulk density had a minimal impact.In the process of natural succession,soil moisture was significantly correlated with the soil organic matter content(p = 0.014),as the soil organic matter could affect soil moisture holding(p = 0.030).Accordingly,we recommend soil organic matter as an effective and integrated index for appraising forest ecosy