金塔县土地沙漠化问题及治理对策

通过对位于黑河中下游的甘肃省金塔县土地沙漠化现状及其危害情况的调查研究,分析了该地区的沙漠化发展成因,并提出了治理对策,以期对黑河流域的生态环境治理有所帮助。     

新疆叶尔羌河和喀什噶尔河流域的生态环境评价及治理对策研究

叶尔羌河和喀什噶尔河流域农业气候资源丰富,但气象灾害也较多;土地面积大,但土壤有机质含量低,次生盐渍化严重;河流径流量大,年际变化小,季节分配不平衡;天然草场面积大,等级低,天然林面积减少,个别地区有沙化倾向;人口多而素质差。对此应处理好维护生态平衡与发展生产的关系;依靠科学技术,以提高单产为主;制止继续破坏生态环境行为;营造人工林;扩大绿肥种植面积,提高地力;对少数民族也实行计划生育,以控制人口数量,提高人口素质。     

The influence of topography on the stream N concentration in the Tanzawa Mountains, Southern Kanto District, Japan

The water chemistry of 51 headwater streams was studied in the Tanzawa Mountains, western fringe of Southern Kanto Plain, Japan. The relationships to soil N processes and catchment topography were also evaluated using a geographic information system with fine-scale map data. The average concentration of total dissolved N was 0.74 mg-N L⁻¹, of which 95% consisted of NO₃ ⁻-N. Stream N concentrations were not different among bedrock geologies and among vegetations of the catchments. Stream NO₃ ⁻-N marginally correlated to soil nitrification. Stream NO₃ ⁻-N also tended to be high in areas with steep and south-facing slopes. These results imply that N transport from Tanzawa forest ecosystems is related to hydrological and biological processes associated with catchment topography. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

基于流域的山区景观格局分析和分区研究--以山东省栖霞市为例

本文以位于胶东半岛中部山区的栖霞市为例,在对整个研究区进行流域提取的基础上,分别统计各流域内的景观指数,并通过聚类分析对整个栖霞市的山区景观进行分区。首先解译2010年Thematic Mapper(TM)遥感影像数据,获得栖霞市景观格局图,以1︰25 000地形图为基础数据源,建立DEM模型,利用ArcGIS水文分析模块将研究区划分为300个子流域。然后根据常用景观格局指数所反映的生态学意义和景观特征信息,并结合研究区内的具体景观结构,选择边缘密度(ED)、多样性指数(SDI)、斑块大小变异系数(PSCOV)、面积加权平均分维数(AWMPFD)和核心区密度(CAD)5个景观指数,并结合各流域的平均高程与空间分布对每一个子流域进行景观格局分析,探讨各子流域景观格局的空间差异,揭示人类活动、自然干扰等各种景观生态机制对区域景观生态的影响。研究结果为:ED值和CAD值随着海拔的增加而逐渐变大,垂直分异特征明显;SDI值呈现出由低海拔向高海拔逐步减少的趋势;PSCOV值随海拔的增加呈现出类似倒"U"形曲线;AWMPFD值不具有明显的垂直分异特征。最后将这5个指数进行聚类分析,同时利用流域主体景观类型对栖霞市进行景观格局分区,各土地利用类型被划分为3个景观生态类型区。研究结果为:一类区面积最小(10.14%),该区域是农作物种植的稳定农业区,景观结构和规模都很稳定,需要继续保护;二类区面积最大(50.93%),各种景观类型呈现空间交错分布,斑块形状复杂,属于自然景观和人文景观的过渡区域,需要加强该区域的土地规划和产业合理布局;三类区面积较大(35.92%),主要集中在中高海拔区域,林地和草坡地居多,开垦难度较大。分区结果能够较好地反映研究区景观生态结构的显著特征与空间分异状况,对栖霞市的土地管理和规划具有一定的指导意义。     

Riparian influences on stream fish assemblage structure in urbanizing streams

We assessed the influence of land cover at multiple spatial extents on fish assemblage integrity, and the degree to which riparian forests can mitigate the negative effects of catchment urbanization on stream fish assemblages. Riparian cover (urban, forest, and agriculture) was determined within 30 m buffers at longitudinal distances of 200 m, 1 km, and the entire network upstream of 59 non-nested fish sampling locations. Catchment and riparian land cover within the upstream network were highly correlated, so we were unable to distinguish between those variables. Most fish assemblage variables were related to % forest and % urban land cover, with the strongest relations at the largest spatial extent of land cover (catchment), followed by riparian land cover in the 1-km and 200-m reach, respectively. For fish variables related to urban land cover in the catchment, we asked whether the influence of riparian land cover on fish assemblages was dependent on the amount of urban development in the catchment. Several fish assemblage metrics (endemic richness, endemic:cosmopolitan abundance, insectivorous cyprinid richness and abundance, and fluvial specialist richness) were all best predicted by single variable models with % urban land cover. However, endemic:cosmopolitan richness, cosmopolitan abundance, and lentic tolerant abundance were related to % forest cover in the 1-km stream reach, but only in streams that had <15% catchment urban land cover. In these cases, catchment urbanization overwhelmed the potential mitigating effects of riparian forests on stream fishes. Together, these results suggest that catchment land cover is an important driver of fish assemblages in urbanizing catchments, and riparian forests are important but not sufficient for protecting stream ecosystems from the impacts of high levels of urbanization.     

绵阳官司河流域天然次生林种群的生态位特征

基于绵阳官司河流域天然次生林群落57块100 m~2的样地调查数据,以微地形地貌作为一维资源位状态,以物种的重要值为生态位计测的资源状态指标,对该流域主要乔木、灌木种群的生态位宽度、生态位相似性和生态位重叠进行了计算与分析。结果表明,主要优势种群的生态位宽度较大,乔木层主要优势种群马尾松、柏木、栓皮栎等Levins生态位宽度值分别为0.841、0.816、0.907,灌木层主要优势种群铁仔、三颗针、黄荆、火棘等Levins生态位宽度值分别为0.985、0.965、0.952、0.882。群落中各种群之间的生态位关系较复杂,生态位宽度较大的物种对资源利用能力较强,彼此之间的生态位相似性和生态位重叠值较大,对资源具有一定的共享性,存在生态位分离现象。种群之间的生态位相似比例和生态位重叠值分布状况,反映了该流域植被恢复过程中森林群落的生态位特征。     

Wetland creation in agricultural landscapes: Biodiversity benefits on local and regional scales

Wetland creation aiming at a simultaneous increase in nutrient retention and species diversity in agricultural landscapes has recently become applied as a catchment-scale compensation measure for past wetland losses. Here, we evaluate if, and to what extend, dual-purpose wetlands benefit local and regional diversity of agricultural landscapes. We analysed composition and α, β, and γ diversity of aquatic macroinvertebrate assemblages among dual-purpose wetlands in an agricultural region in southwest Sweden in relation to local (water quality, wetland morphology, succession stage, proximity to other aquatic habitats) and landscape parameters (regional connectivity, wetland density). Diversity of mature agricultural ponds was used as a standard to evaluate the value of dual-purpose wetlands. Dual-purpose wetlands sustained α, β, and γ diversity similar to that of natural lentic water bodies in agricultural landscapes in the region and elsewhere. Over 80% of the overall species richness was attributed to β diversity, and each created wetland contributed to overall species accumulation. Ecosystem parameters explained 19% of the compositional variation among assemblages, but were only marginally related to diversity. Wetland density promoted α and γ diversity, while spatial heterogeneity (β) remained equally high, independent of wetland density. Our results indicate that catchment-scale wetland creation for simultaneous retention and diversity purposes benefits the biodiversity of agricultural landscapes, particularly if the density of aquatic habitats is increased by at least 30%.     

洱海流域土壤侵蚀动态变化研究

以云南洱海流域为研究对象,根据已有的流域DEM、Landsat-5 TM卫星数据和当地降雨、土壤类型等资料,在GIS、Erdas及ArcView软件支持下,应用USLE模型计算了洱海流域1989—2006年土壤侵蚀变化并对其土壤侵蚀特征进行了分析。研究表明:轻度侵蚀由占总面积的13.89%下降到6.47%,中度侵蚀由占总面积的6.49%增至14.04%,微度和极强烈侵蚀小幅增加,强烈和剧烈侵蚀小幅减少;微度、轻度、强烈和剧烈侵蚀多转化为中度侵蚀,面积分别为22.20、123.539、.68和22.91 km2,中度侵蚀多转化为微度侵蚀,极强烈侵蚀多转化为剧烈侵蚀;18年来,土壤侵蚀强度与面积年均变化率以中度侵蚀最大(6.46%),轻度、强烈、剧烈和微度侵蚀年均变化率分别为-2.97%、-0.11%、-0.10%、0.056%,极强烈侵蚀年均变化率最小(0.020%)。     

Response of water and nutrient fluxes to improvement fellings in a tropical montane forest in Ecuador

Management of natural forests might be one option to reduce the high deforestation rate in Ecuador. We therefore evaluated the response of water and nutrient cycles in a natural tropical montane forest to improvement fellings with the aim of favoring economically valuable target trees which will later be harvested with additional ecosystem impacts not considered here.