【摘要】 为揭示尾巨桉（Eucalyptus urophylla×E.grandis）人工林与生态环境的互作关系，客观评价尾巨桉人工林的生态功能，本研究依托南宁桉树森林生态系统广西野外科学观测研究站和湛江桉树森林生态系统国家定位观测研究站，以尾巨桉人工林为研究对象，观测单木蒸腾耗水量、林分蒸散耗水量和根系吸水来源；分析枯落物量及分解归还特征，并探讨尾巨桉纯林改培混交林对土壤质量的影响；解析林下植物多样性变化规律；评估碳储量和固碳效率。结果发现：尾巨桉单木日均蒸腾耗水量1.32 mm,年蒸腾耗水量349 mm,占当年降水量的27%;尾巨桉林年蒸散耗水量占当年降水量的82%;尾巨桉林的凋落物养分归还以氮元素为主，归还总量随林龄增长而逐渐增加，延长尾巨桉培育周期有助于凋落物分解、养分还土；纯林改培套种灰木莲（Magnoliaceae glance）的混交林能够显著改善土壤质量；广西的尾巨桉林中有维管植物120科369属584种，其中包括灌木201种、草本186种；明确中龄尾巨桉人工林白天为碳汇、夜间为碳源，其中夏季和秋季吸收固定CO₂的能力最强，每日净吸收固定CO₂约为11.0 g·m^-2,转化为每年净固定碳约为10.9 t·hm^-2。阶段性观测研究表明尾巨桉生长未吸收消耗大量水分，纯林改培为混交林可显著提升土壤质量，林下植物物种多样性随林龄增长而增加；桉树的碳汇功能强于其他主要造林树种，该结论为客观认知桉树人工林与生态环境的互作关系提供了基础资料，为优化桉树人工林经营方案提供了参考。更多还原

【Abstract】 To unveil the interplay between the Eucalyptus urophylla×E.grandis plantations and the ecological environment, and to objectively assess the ecological functions of the E.urophylla×E.grandis plantations, this study relies on the Nanning Eucalyptus Forest Ecosystem Guangxi Wild Field Scientific Observation Research Station and the Zhanjiang Eucalyptus Forest Ecosystem National Positioning Observation Research Station.With the E.urophylla×E.grandis plantations as the research subject, the study observes the transpiration of individual trees, stand evapotranspiration, and root water absorption.It analyzes litterfall quantity and decomposition and restitution characteristics and explores the impacts of converting the E.urophylla×E.grandis plantations to mixed forest on soil quality.The study also examines the changes in understory plant diversity and evaluates carbon storage and sequestration efficiency.The results showed that the average daily evapotranspiration of a single tree of the E.urophylla×E.grandis was 1.32 mm, and the annual evapotranspiration of the E.urophylla×E.grandis was 349 mm, which accounted for 27% of the precipitation of the same year; the annual evapotranspiration of the E.urophylla×E.grandis plantations accounted for 82% of the precipitation of the same year.Nitrogen is the most important nutrient returned from apoptosis in the E.urophylla×E.grandis plantations, and the total amount of nutrients returned increased with the age of the forest, and prolonging the cultivation cycle of the E.urophylla×E.grandis helped the decomposition of apoptotic materials and nutrient return to the soil; Pure forest conversion to mixed forests planted with Manglietia glauc significantly improved soil quality.In Guangxi, there are 584 species of vascular plants in 120 families and 369 genera, including 201 species of shrubs and 186 species of herbs in the E.urophylla×E.grandis plantations; it is clear that the middle-aged E.urophylla×E.grandis plantations are carbon sinks during the daytime and carbon sources during the nighttime.In the summer and fall seasons, the plantation forests had the strongest ability to absorb and fix CO₂,with a daily net absorption of about 11.0 g·m^-2·d^-1,which was converted into an annual net fixed carbon of about 10.9 t·hm^-2·a^-1.Stage-by-stage observations showed that the growth of the E.urophylla×E.grandis did not absorb and consume a large amount of water, and the conversion of pure forest to mixed forest could significantly improve soil quality, and the diversity of plant species in the understory increased with the age of the forest, and the carbon sink function of eucalyptus was stronger than that of other major afforestation species.These findings provide basic information for the objective understanding of the interactions between eucalyptus plantation forests and the ecological environment, and provide theoretical basis for the optimization of eucalyptus plantation forest management plan.更多还原