太白山红桦林林隙特征的研究

对太白山红桦林林隙的一般特征和干扰状况进行了初步研究,分析了植被中林隙的数量、类型及成因,并对林隙形成木的类型、数量、物种构成和径级结构做了分析.结果表明,太白山红桦林林隙以自然立枯形成的最多;林隙线状密度为23.5个/km;冠空隙面积在20～80m2范围内的最多,冠空隙总面积占整个林分面积的4.7%;扩展林隙的面积在50～100m2范围内的最多,占整个林分的11.9%;林隙的形成木以红桦为主,径级在20～40cm范围内的占绝大部分;在太白山红桦林中,大多数的林隙由1～3株林隙形成木形成,其中单株形成木形成的林隙最多,每个林隙的林隙形成木平均为1.51株;林隙的腐烂等级为C级的分布较多;冠空隙径高比多分布在0.30～0.45之间,扩展林隙径高比多分布在0.60～0.80之间;林隙内幼苗主要有红桦、华山松,在大面积的林隙内红桦幼苗占绝对优势.图1表5参26     

环境保护中的退耕还林(草)工程与可持续发展

环境保护是我国的一项基本国策,退耕还林(草)是保护环境的有效措施．加强环境教育,完善环境法制,加强现代科技管理,发展生态经济,通过退耕还林(草)工程贯彻可持续发展战略,最终达到环境与经济、社会“共赢”的目的。     

Harvesting in an eight-species ecosystem

The theory for a general equilibrium ecosystem model that can include large number of interacting species is presented. Features include: (1) individual plants and animals are assumed to behave as if they are maximizing their net energy intake, (2) short- and long-run equilibriums are obtained, (3) species’ population adjustments depend on individual net energies. The theory is applied using simulations of an eight-species Alaskan marine ecosystem for which a “natural” equilibrium is calculated. Humans are introduced by adding a regulated open access fishery that harvests one of the species. Fishing impacts the fish population as well as the populations of other species, including Stellar sea lions, an endangered species. The sensitivity of fish and nonfish species populations to harvesting are calculated.     

川中半自然型防护林演替过程中的物种多样性

四川中部绵阳官司河流域的半自然型林是长江中上游地区防护林的一个较典型类型。本文以它为研究对象，对群落的物种多样性及其在次生演替过程中的动态变化趋势进行了初步研究，并结合影响多样性的几个主要环境因子进行了相关性分析。结果表明：（1）现阶段该防护林的植物种类组成和群落结构均较简单，松、柏、栎混交的针阔叶林占绝对优势，其物种多样性较小，但随着群落次生演替的进展，各层次的多样性趋于增加；（2）用灰色系统理论的关联度分析方法研究群落的物种多样性与主要环境因子的相关性是可行的。经测定，研究区的土壤pH值，外界干扰度和土壤含水量等指标对防护林的物种多样性有显著的影响。图2表3参16     

两种评价森林资源生态环境效益计量方法的比较

对评价森林资源生态环境效益的 2种方法进行了比较 ,阐述了这 2种方法的优缺点 ,通过案例分析可知 :森林资源环境效果评价法获得的评价值大 ,而意愿调查法的评价值小 ,并说明了导致这 2种方法评价值不同的原因。     

同化箱装置在温带落叶阔叶林CO2交换研究中的应用

本文探讨了森林生态系统中植物－－土壤－－大气ＣＯ２气体交换测定装置。本装置在草原生态系统植物群落光合作用测定装置基础上改进而来，适用于森林地带无交流电源，效能运输不便的地区，利用便携式ＣＯ２红外线分析仪和粉尘采样器替代气泵，具有经济，轻便，实用等特点。     

人工湿地污水处理技术与节约型城市的建设

人工湿地污水处理技术是一个完整的生态系统，正不断得到研究应用和发展，具有出水水质好、增加绿地面积、改善和美化生态环境、操作简单、维护和运行费用低廉等优点，是建设节约型城市的重要措施之一，具有极其广阔的应用前景。     

Natural pollution caused by the extremely acidic crater lake Kawah Ijen, East Java, Indonesia

Background. Aims and Scope Lakes developing in volcano craters can become highly acidic through the influx of volcanic gases, yielding one of the chemically most extreme natural environments on earth. The Kawah Ijen crater lake in East Java (Indonesia) has a pH 〈 0.3. It is the source of the extremely acid and metal-polluted river Banyupahit (45 km). The lake has a significant impact on the river ecosystem as well as on a densely populated area downstream, where agricultural fields are irrigated with water with a pH between 2.5 and 3.5. The chemistry of the river water seemed to have changed over the past decade and the negative effect in the irrigation area increased. A multidisciplinary approach was used to investigate the altered situation and to get insight in the water chemistry and the hydrological processes influencing these alterations. Moreover, a first investigation of the effects of the low pH on ecosystem health and human health was performed. Methods Water samples were taken at different sites along the river and in the irrigation area. Sampling for macroinvertebrates was performed at the same sites. Samples of soil and crop were taken in the irrigation area. All samples were analysed for metals (using ICP-AES) and other elements, and concentrations were compared to local and international standards. Results and Discussion The river carries a very high load of SO4, NH4, PO4, Cl, F, Fe, Cu, Pb, Zn, Al and other potentially toxic elements. Precipitation and discharge data over the period of 1980 – 2000 clearly show that the precipitation on the Ijen plateau influences water chemistry of the downstream river. Metal concentrations in the river water exceed the concentrations mentioned in Indonesian and international quality guidelines, even in the downstream river and the irrigation area. Some metal concentrations are extremely high, especially iron (up to 1600 mg/l) and aluminium (up to 3000 mg/l). The food-webs in the acidic parts of the river are highly underdeveloped. No invertebrates were present in the extremely acid water and, at pH 2.3, only chironomids were found. This also holds true for the river water with pH 3.3 in the downstream area. Agricultural soils in the irrigation area have a pH of 3.9 compared to a pH of 7.0 for soils irrigated with neutral water. Decreased yields of cultivated crops are probably caused by the use of Al containing acid irrigation water. Increased levels of metals (especially Cd, Co, Ni and Mn) are found in different foodstuffs, but still remain within acceptable ranges. Considering local residents” diets, Cd levels may lead to an increased risk for the human health. Fluoride exposure is of highest concern, with levels in drinking water exceeding guideline values and a lot of local residents suffering from dental fluorosis. Conclusions, Recommendations and Outlook In short, our data indicate that the Ijen crater lake presents a serious threat to the environment as well as human health and agricultural production.     

森林降水化学的变化特征和机理

研究并比较了湖南酸雨区韶山小集水区林内降水的化学特征，结果表明，与大气降水相比，穿冠水和地表穿透水中的富集的离子浓度除了NO3^-和Na^ 外均明显增加，到达地表的降水离子增加倍数最高达34．3倍；离子总量最高倍数为8．1倍，乔木树冠层的离子富集作用大于灌木层。韶山的大气降水、穿冠水和地表穿透水的年均pH分别为4．61、5．54和5．85。持续大量的降水对森林上空的污染物有较高的清除效果。     

我国海岸带生态环境问题及其调控对策

海岸带是陆海交互作用的地带 ,是全球变化研究的重要组成部分 ;同时人类活动对海岸带的环境变迁又有着举足轻重的影响。本文综述了影响我国海岸带生态环境变迁的 10个重要的环境问题 ,并提出了应对海岸带生态环境退化的 6种调控对策 ,其中实行一体化的海岸带综合管理体制是实现海岸带可持续发展的最重要的对策之一