城市森林研究进展

城市森林是一门正在形成和发展的新兴学科 ,它从森林学的角度 ,对城市这一人类活动的中心进行研究探讨 ,为我们认识和解决当代城市问题 ,开辟了新的思路。随着城市人口剧增 ,工业化进程加速发展 ,城市环境质量迅速下降 ,造成了大气、水、土壤、噪声等污染 ,而且使城市热岛效应不断加剧 ,严重损害了人类的身心健康。我国已经开始关注和探讨城市森林建设 ,但目前多局限于理论研究上 ,具体实践还刚起步 ,对城市森林的概念、范畴、原则、标准和实施措施还有不同的理解 ,并且许多研究还囿于林业的范畴 ,如何真正与城市有机结合还有待于进一步探讨…  

鼎湖山季风常绿阔叶林的水文学过程及其氮素动态

 本文对鼎湖山南亚热带季风常绿阔叶林—黄果厚壳桂(Cryptocarya coneinna)、鼎湖钓樟(Lindera chunii)群落的水文学过程以及水系统中的氮素动态特征进行了初步研究。结果显示：所研究的群落中雨水输入的氮量较高，达35.57kg·ha-1，但渗入土壤及地表径流输出的氮也多，分别为18.28和9.25kg·ha-1·yr-1，输入输出之差为8.04kg·ha-1·yr-1。雨水对林冠的氮素淋溶量为4.72kg·ha-1·yr-1。通过回归分析，发现各类型水中含氮量与降雨量之间存在较显著的直线相关关系。不同树种的树干茎流中氮浓度存有差别。  

森林对水文过程影响研究进展

根据森林对水文过程的影响，森林水文学研究可以分为3个相互关联的方面：森林植被变化影响水量和水质定位试验研究；森林植被变化对水文循环机制的影响；旨在为资源管理和工程建设提供决策依据的基于物理过程分布式参数森林水文模型开发，定位试验研究不仅可以为森林水文模型参数化提供第一手资料，同时也可以揭示森林植被影响径流形成机制和进行径流成份的分割，径流形成机机制的研究则有助于改善基于物理过程模型的开发，模型研究反过来又可以为改进试验研究和径流形成机制研究提供指导。本文对以上3个方面的国内外研究进展进行了较为系统的概括。  

土地覆被变化的水文响应模拟研究

采用近年来快速发展的水文模型模拟的手段，应用SWAT模型模拟了长江上游梭磨河流域不同土地覆被情景下的多年降水径流关系，定量地评估了梭磨河流域的土地覆被变化对径流、蒸发和洪峰流量的影响．结果表明，随着土地覆被状况由无植被到全是有林地覆被，径流深减小，蒸发量增加，枯季径流深减小幅度明显小于雨季的减小幅度，而且雨季初期径流深减小的幅度大于雨季后期．相同的洪水重现期，流域全为有林地覆被的情景比无植被的情景洪峰流量减小31．2％．现状覆被与未来最佳覆被之间在较大洪水上的差别不大，在较小洪水上的差别稍大．  

荒漠绿洲NDVI与气候、水文因子的相关分析

 通过利用1992～1996年NOAA/AVHRR逐旬的归一化植被指数（NDVI）数据和阜康气候、水文资料，分别对绿洲和荒漠进行了NDVI与气候、水文因子间的相关分析，得出了一些初步结论：绿洲与荒漠NDVI具有不同的季节变化规律；与绿洲NDVI相关显著的因子依次为气温、地下水位和降水，  

南亚热带季风常绿阔叶林水文功能及其养分动态的研究

 根据在鼎湖山季风常绿阔叶林集水区3年的观测结果，对这一南亚热带地带性植被的水文功能进行了较深入的探讨。由于林分结构复杂，季风常绿阔叶林对大气降水具有较高的林冠截留率，截留率的季节变化动态与降水量的季节分配有关。该森林土壤结构良好，其渗水速度快，加上有较厚的枯落物层，对于减缓地面径流，减少水土流失，功效甚大。但由于土层较薄，其蓄水功能有限。该森林的径流量占总降水量的比例特别是地表径流所占比例较小，分别为50.22％和14.19％。其季节分配有利于保持水土和植物生长。由于土壤蓄水量变化出现负值，用水量平衡法计算得出鼎湖山季风常绿阔叶林年蒸发散量为1323.98mm，占大气降水量的51.81％。该森林的降水中主要营养元素浓度较高，降水带来大量的养分，特别是氮素的年输入量高达35.29kg·hm-2。淋溶也给该森林带来较高的养分归还量，其中钾的淋溶量高达35.65kg·hm-2；镁的淋溶量高达8.9kg·hm-2，为林外雨输入的2.37倍。径流中的氮输出为28.35kg·hm-2，降水中的氮素净输入量为6.94kg·hm-2；但镁的净输入呈负值。  

The interaction between water movement, sediment dynamics and submersed macrophytes

Water movement in freshwater and marine environments affects submersed macrophytes, which also mediate water movement. The result of this complex interaction also affects sediment dynamics in and around submersed macrophyte beds. This review defines known relationships and identifies areas that need additional research on the complex interactions among submersed macrophytes, water movement, and sediment dynamics. Four areas are addressed: (1) the effects of water movement on macrophytes, (2) the effects of macrophyte stands on water movement, (3) the effects of macrophyte beds on sedimentation within vegetated areas, and (4) the relationship between sediment resuspension and macrophytes. Water movement has a significant effect on macrophyte growth, typically stimulating both abundance and diversity of macrophytes at low to moderate velocities, but reducing growth at higher velocities. In turn, macrophyte beds reduce current velocities both within and adjacent to the beds, resulting in increased sedimentation and reduced turbidity. Reduced turbidity increases light availability to macrophytes, increasing their growth. Additionally, macrophytes affect the distribution, composition and particle size of sediments in both freshwater and marine environments. Therefore, establishment and persistence of macrophytes in both marine and freshwater environments provide important ecosystem services, including: (1) improving water quality; and (2) stabilizing sediments, reducing sediment resuspension, erosion and turbidity.  

水文尺度转换研究进展

介绍了水文尺度、尺度问题和尺度转换的概念，重点与难点在流域的空间异质性和水文通量的时空变异性；给出了进行尺度转换的3种途径，即分布式水文模拟、分形理论和统计自相似性分析；最后在已有成果的基础上，提出了目前研究中存在的问题及未来的发展方向。  

Fog in the California redwood forest: ecosystem inputs and use by plants

Fog has been viewed as an important source of moisture in many coastal ecosystems, yet its importance for the plants which inhabit these ecosystems is virtually unknown. Here, I report the results of a 3-year investigation of fog inputs and the use of fog water by plants inhabiting the heavily fog inundated coastal redwood (Sequoia sempervirens) forests of northern California. During the study period, 34%, on average, of the annual hydrologic input was from fog drip off the redwood trees themselves (interception input). When trees were absent, the average annual input from fog was only 17%, demonstrating that the trees significantly influence the magnitude of fog water input to the ecosystem. Stable hydrogen and oxygen isotope analyses of water from fog, rain, soil water, and xylem water extracted from the dominant plant species were used to characterize the water sources used by the plants. An isotopic mixing model was employed to then quantify how much fog water each plant used each month during the 3-year study. In summer, when fog was most frequent, ∼19% of the water within S.sempervirens, and ∼66% of the water within the understory plants came from fog after it had dripped from tree foliage into the soil; for S.sempervirens, this fog water input comprised 13–45% of its annual transpiration. For all plants, there was a significant reliance on fog as a water source, especially in summer when rainfall was absent. Dependence on fog as a moisture source was highest in the year when rainfall was lowest but fog inputs normal. Interestingly, during the mild El Niño year of 1993, when the ratio of rainfall to fog water input was significantly higher and fog inputs were lower, both the proportion and coefficient of variation in how much fog water was used by plants increased. An explanation for this is that while fog inputs were lower than normal in this El Niño year, they came at a time when plant demand for water was highest (summer). Therefore, proportional use of fog water by plants increased. The results presented suggest that fog, as a meteorological factor, plays an important role in the water relations of the plants and in the hydrology of the forest. These results demonstrate the importance of understanding the impacts of climatic factors and their oscillations on the biota. The results have important implications for ecologists, hydrologists, and forest managers interested in fog-inundated ecosystems and the plants which inhabit them.  

基于生态水文学原理的湖泊最小生态需水量计算

近几十年来,由于人类活动的加剧以及全球气候的变化,湖泊普遍出现了萎缩、水位下降、水量锐减、湖水盐化、水质污染、富营养化、甚至干涸消亡等状况。确保湖泊生态系统必需的最小水量是解决可能出现的湖泊严重水资源和生态系统危机的区域问题之一。从生态水文学原理出发,对湖泊最小生态需水量的概念进行了探讨,并提出了计算最小生态需水量的3种方法:1曲线相关法;2功能法;3最低生态水位法。在最低生态水位法中,其方法有最低年平均水位法和年保证率设定法。一旦湖泊最小生态需水量得以确定,将为水资源管理部门的水资源合理配置和湖泊管理提供综合性、权威性及可操作性决策依据,为退化湖泊生态系统的恢复与重建提供科学基础。