Linking Land-use, Water Body Type and Water Quality in Southern New Zealand

Land-use and vegetation cover have been linked to the nutrient levels (nitrogen, phosphorus) of surface waters in several countries. However, the links generally relate to streams and rivers, or to specific types of standing water, for example shallow lakes in a geologically defined region. We measured physical variables and nutrient chemistry of 45 water bodies representative of the wide range of lentic wetland environments (swamps, riverine wetlands, estuaries, reservoirs, shallow lakes, deep lakes) in Otago, New Zealand, and related these to catchment variables and land-use in order to assess the potential influence of catchment modification on water quality of these diverse wetlands. Catchment boundaries and land cover were derived from maps using ArcView GIS software. Our predictions that concentrations of nutrients and other components of water quality would correlate positively with the nature and intensity of catchment modification were confirmed in multivariate analyses. Physical and chemical measures were positively related to the extent of modification in the catchment (percentage of the catchment in pasture, planted forest, scrub and urban areas), and negatively related to lack of catchment modification (more of the catchment in bare ground, tussock grassland and indigenous forest). The strong negative correlations between nutrient concentrations, suspended sediment, water colour and the percentage of tussock cover in the catchment imply that increased conversion of the␣native tussock grassland to pastoral farming in␣Otago will increase nutrient concentrations and␣reduce water quality of the diverse lentic ecosystems.     

塔里木盆地沙漠化防治措施及其效益

土地沙漠化是干旱,半干旱地区普遍存在的一个重大环境问题。塔里木盆地是我国沙漠化危害最严重的地区之一,但干旱多风的自然条件引起的沙漠化,仅占现代沙漠化面积的１５．１３％,说明沙漠化土地是可以治理的,本文概述了农田林网,林网内农林复合经营,防沙林带,灌草带,造林固沙等沙漠化防治措施及其效果。     

准噶尔盆地南缘荒漠鼠类的微栖息地选择

依据地形及其内植被组成特征,划分出５种微栖息地类型。通过在不同物候期的观测表明,４种共存的鼠种间存在着明显的微栖息地分离。二足型跳鼠选择在开阔的空间活动四足型沙鼠则主要在多年生灌丛下取食。二种类型的鼠类微栖息地选择都不同程度地与同的多年生灌木     

柴达木盆地水资源与合理开发利用研究

本文通过对柴达木盆地水资源量、农业水资源开发利用现状分析,结合盆地水土资源匹配情况与经济发展方向,提出了实现盆地水资源合理开发利用的基本途径,并指出在实施水资源开发利用中所要注意的具体问题,为盆地可持续发展提供依据。     

柴达木盆地主要河流的水化学特征

为了保护水资源,不仅需要了解人为引起的水质污染状况,而且需要研究河流水体在自然界的循环过程中所形成的水化学特征及其时空变化。本文对柴达木盆地主要河流的水化学特征进行了分析、研究,对水质状况进行了评价。     

Quantifying the nitrogen retention capacity of natural wetlands in the large-scale drainage basin of the Baltic Sea

We estimate the nitrogen retention capacity of natural wetlands in the 1.7 million km² Baltic Sea drainage basin, using a wetland GIS data base. There are approximately 138,000 km² of wetlands (bogs and fens) in the Baltic Sea drainage basin, corresponding to 8% of the area. The input of nitrogen to natural wetlands from atmospheric deposition was estimated to 55,000–161,000 ton y¹. A map of the deposition of both wet and dry nitrogen is presented. The input from the human population was estimated to 255,000 ton y¹ in terms of excretory release in processed sewage water. There may also be leakage from forests and agricultural land into the wetlands. Due to lack of data on hydrology and topography, such potential nitrogen sources are not accounted for here. The capacity of the wetlands to retain the atmospheric deposition of nitrogen was estimated to 34,000–99,000 ton y¹. The potential retention by wetlands was estimated to 57,000–145,000 ton y¹ when the nitrogen input from the human population was added. If drained wetlands were to be restored and their area added to the present wetland area, the nitrogen retention capacity was estimated to increase to 196,000–261,000 ton y¹. Our results indicate that existing natural wetlands in the Baltic Sea drainage basin annually can retain an amount of nitrogen which corresponds to about 5–13% of annual total (natural and anthropogenic) nitrogen emissions entering the Baltic Sea. The ecosystem retention service performed by wetlands accounts for a substantial nitrogen removal, thereby reducing the eutrophication of the Baltic Sea.     

北洛河流域植被恢复的支撑体系

北洛河流域自实行退耕还林政策以来取得了显著成效,但是实践证明植被恢复不是简单的种树种草,必须要根据生态学原则合理种植,既要有技术支撑,还必须考虑到退耕后农民的生存问题,也就是粮食与能源的问题,并要保证农民有一定的经济收入,最后指出要解决好以上问题,必须靠国家政策的支撑。     

银川盆地富硒土地资源研究

在银川盆地首次发现大面积富硒区.该富硒区具有富硒土层厚、硒含量适中、宜于开发利用等特点.富硒土地分布区不仅硒含量高,而且污染有害元素的含量特别低,呈"原生态"的自然状态.初步分析认为银川盆地土地富硒主要与成土母质(母岩)有关.     

塔里木河流域“四源一干”生态环境中存在的问题及其成因分析

塔里木河是新疆南疆地区最重要的水源,被誉为“生命之河”。本文章主要针对塔里木河流域“四源一干”生态环境中存在的问题进行了探讨并分析了成因。     

青海湖流域沙地植物群落多样性研究

土地沙漠化是青海湖流域重要的生态问题之一,明晰区域内不同沙化阶段植物群落的演化特征,有助于为该区沙漠化防治工作有效开展提供科学依据。本研究通过野外样方调查并应用方差分析、主成分分析和相关性分析,厘清该区潜在、轻度、中度、重度和极重度沙化阶段植物组成特征与变化规律。结果表明,随沙化程度加剧,植物优势种从矮生嵩草、草地早熟禾和垂穗披碱草演替为青海固沙草、驼绒藜和沙蒿,生活型从中生向旱生演替;植物盖度、高度、地上生物量和多度依次降低;物种丰富度、Shannon-Wiener指数、Simpson指数与Pielou指数均为先升后降,轻度沙化阶段最高,符合“中度干扰假说”。沙化过程对多样性指数影响为Shannon-Wiener指数>物种丰富度>Simpson指数>Pielou指数,除Pielou指数外,其余多样性指数与植被特征相关性显著。研究结果可为青海湖流域沙化防治及群落多样性研究提供参考。