陕北地区土地利用与生态承载力动态变化分析

本文研究了陕北地区2003-2007年土地利用类型结构、动态度、程度以及生态承载力的时空动态变化,并采用回归分析方法研究了陕北地区延安市、榆林市土地利用程度与人均生态承载力的关系。结果表明,陕北地区耕地、牧草地、未利用土地面积总量及其比例减小,园地、林地、居民点及工矿用地、交通用地、水域面积增加;土地利用程度不断降低,总生态承载力和人均生态承载力逐年递减。论文还分析讨论了土地利用动态变化对生态承载力的影响以及相应的对策建议等问题。     

Indirect Effects of Pandemic Deer Overabundance Inferred from Caterpillar‐Host Relations

Externally feeding phytophagous insect larvae (i.e., caterpillars, here, larval Lepidoptera and sawflies, Hymenoptera: Symphyta) are important canopy herbivores and prey resources in temperate deciduous forests. However, composition of forest trees has changed dramatically in the eastern United States since 1900. In particular, browsing by high densities of white‐tailed deer (Odocoileus virginianus) has resulted in forests dominated by browse‐tolerant species, such as black cherry (Prunus serotina), and greatly reduced relative abundance of other tree species, notably pin cherry (Prunus pensylvanica) and birches (Betula spp.). To quantify effects of these changes on caterpillars, we sampled caterpillars from 960 branch tips of the 8 tree species that comprise 95% of trees in Allegheny hardwood forests: red maple (Acer rubrum), striped maple (Acer pensylvanicum), sugar maple (Acer saccharum), sweet birch (Betula lenta), yellow birch (Betula allegheniensis), American beech (Fagus grandifolia), black cherry, and pin cherry. We collected 547 caterpillar specimens that belonged to 66 Lepidoptera and 10 Hymenoptera species. Caterpillar density, species richness, and community composition differed significantly among tree species sampled. Pin cherry, nearly eliminated at high deer density, had the highest density and diversity of caterpillars. Pin cherry shared a common caterpillar community with black cherry, which was distinct from those of other tree hosts. As high deer density continues to replace diverse forests of cherries, maples, birches, and beech with monodominant stands of black cherry, up to 66% of caterpillar species may be eliminated. Hence, deer‐induced changes in forest vegetation are likely to ricochet back up forest food webs and therefore negatively affect species that depend on caterpillars and moths for food and pollination. Efectos Indirectos de la Sobreabundancia de Venados Pandémicos Inferida de Relaciones Orugas‐Huéspedes     

Associations of Grassland Bird Communities with Black‐Tailed Prairie Dogs in the North American Great Plains

Colonial burrowing herbivores can modify vegetation structure, create belowground refugia, and generate landscape heterogeneity, thereby affecting the distribution and abundance of associated species. Black‐tailed prairie dogs (Cynomys ludovicianus) are such a species, and they may strongly affect the abundance and composition of grassland bird communities. We examined how prairie dog colonies in the North American Great Plains affect bird species and community composition. Areas occupied by prairie dogs, characterized by low percent cover of grass, high percent cover of bare soil, and low vegetation height and density, supported a breeding bird community that differed substantially from surrounding areas that lacked prairie dogs. Bird communities on colony sites had significantly greater densities of large‐bodied carnivores (Burrowing Owls [Athene cunicularia], Mountain Plovers, [Charadrius montanus], and Killdeer [Charadrius vociferus]) and omnivores consisting of Horned Larks (Eremophila alpestris) and McCown's Longspurs (Rhynchophanes mccownii) than bird communities off colony sites. Bird communities off colony sites were dominated by small‐bodied insectivorous sparrows (Ammodramus spp.) and omnivorous Lark Buntings (Calamospiza melanocorys), Vesper Sparrows (Pooecetes gramineus), and Lark Sparrows (Chondestes grammacus). Densities of 3 species of conservation concern and 1 game species were significantly higher on colony sites than off colony sites, and the strength of prairie dog effects was consistent across the northern Great Plains. Vegetation modification by prairie dogs sustains a diverse suite of bird species in these grasslands. Collectively, our findings and those from previous studies show that areas in the North American Great Plains with prairie dog colonies support higher densities of at least 9 vertebrate species than sites without colonies. Prairie dogs affect habitat for these species through multiple pathways, including creation of belowground refugia, supply of prey for specialized predators, modification of vegetation structure within colonies, and increased landscape heterogeneity. Asociaciones de Comunidades de Aves de Pastizales con Perros de la Pradera en la Gran Llanura de Norte América     

南海北部沿岸牡蛎体内PCBs的时空分布特征及评价

于2008~2012年间在南海北部沿岸海域的23个重要港湾采集近江牡蛎(Crassostrea rivularis Gould )样品,用气相色谱法测定其中多氯联苯(PCBs)的残留量,并对其残留水平、时空分布趋势、组成特征以及食用安全性进行探讨与评价.结果表明:南海北部沿岸牡蛎体内的PCBs的含量范围在8.11~29.10ng/g之间(湿重,下同),平均值是(16.57±4.40)ng/g,出现频率呈正态分布.在时间上,广东、广西和海南沿岸PCBs含量随时间呈下降的总体趋势;空间分布上,珠江口岸段PCBs含量明显高于粤东、粤西、广西和海南4个岸段.PCBs同系物中以五氯联苯在总PCBs含量最高,占47.9%,其次是三氯和四氯联苯,二者之和占总PCBs的30.6%; 同系物以PCBl05、PCB118和PCB101+113为优势组分,3者之和占总量的百分比为24.0%.南海北部沿岸牡蛎体内的PCBs残留量远低于国内外相关食品安全限量标准,估算的沿海居民食用牡蛎的PCBs 暴露量为5.52ng/(kg·d),仅占世界卫生组织(WHO)设定的每日耐受量值的27.6%.PCBs的二 毒性当量(TEQ)平均值为39.4pg/g.     

藏北草地生态系统可持续发展能力评价

藏北草地是我国重要的畜牧业生产基地和生态安全屏障。然而,草地退化引发了一系列的生态、经济、环境和社会问题,不仅直接威胁到我国的生态屏障安全和当地的畜牧业生产,而且严重影响着藏北草地生态系统的可持续发展。研究以藏北那曲地区为例,利用复合生态系统场方法,构建了以生态功能、生产功能和生活功能为基础的可持续发展评价指标体系和模型,并通过对1985-2008年那曲地区草地生态系统的发展变化分析,定量评价了草地生态系统的可持续发展能力。评价结果表明,藏北那曲草地生态系统的发展位已超过了系统的最大承载能力,发展势缺乏潜能,协调性较差,可持续发展度很低,草地生态系统处于不可持续的发展状态。     

不同草地资源水平牧户对气候变化的感知与偏差途径

人群感知是气候变化适应行为形成的重要信息基础,基于对中国北方草地草甸草原、典型草原、荒漠草原、草原化荒漠、沙地、农牧交错带等地区1292个牧户的问卷访谈,分2轮调查研究了不同草地类型地区牧民对气候变化的感知,与气候实值比较分析,并研究了牧民气候变化感知的偏差途径,结果表明:1980~2009年间研究区温度变化倾向率为0.63℃/10a(P0.05);温度较强的趋势性与牧民对其感知的分歧存在偏差,降水无明显变化与不同地区牧民感知明确的趋势性判断存在偏差;受草场变化等环境信息的传导是气候变化感知偏差形成的重要原因,其中,降水感知与环境感知之间具有较强的关系,存在明显的传导过程,而温度感知的传导性不明显;通过Probit模型分析显示,气候变化传导感知与否主要与牧户距离行政中心距离、户主年龄、教育背景、载畜水平、草畜资源等因素有关.     

基于FY-3A/VIRR和TERRA/MODIS数据藏北干旱监测对比

为获得藏北地区干旱遥感监测的方法,以及验证FY-3A/VIRR数据在藏北地区干旱监测的可行性,论文基于2015年7月25日—8月4日FY-3A/VIRR和TERRA/MODIS数据,计算NDVI和EVI反演温度植被干旱指数（TVDI）,利用实测20 cm土壤水分数据和气象站点累计降水量验证并对比了两种数据源、不同TVDI的遥感干旱监测的精度。结果表明：1）拟合干湿边时,噪点和拟合像元数影响TVDI监测的精度,去除噪点可提高干湿边拟合精度和干旱监测精度;2）MODIS-TVDI_E（下标E表示EVI反演）、MODIS-TVDI_N（下标N表示NDVI反演）、FY/VIRR-TVDI_E、FY/VIRR-TVDI_N与实测20 cm土壤水分数据和累计降水量的相关性检验都达到了0.05的水平,说明基于两种数据源采用TVDI的方法都能有效监测藏北地区干旱。其中,MODIS-TVDI_E和FY/VIRR-TVDI_E监测精度分别高于MODIS-TVDI_N和FY/VIRR-TVDI_N,表明TVDI_E的监测精度优于TVDI_N。MODIS-TVDI的监测精度高于FY/VIRR-TVDI,反映MODIS数据在藏北地区干旱监测精度优于FY/VIRR数据;3）基于MODIS-TVDI_E和FY/VIRR-TVDI_E划分的藏北地区干旱空间特征结果大体相同,说明FY/VIRR数据也可作为气象部门监测干旱的业务化产品,为藏北地区干旱监测提供数据支撑。     

基于RS/GIS的天山北坡经济带生态环境质量综合评价研究

本文采用综合指数评价法，以RS／GIS技术解译的土地利用／土地覆盖数据为信息源，对天山北坡经济带生态环境质量进行评价、排序及分级。结果得出：乌鲁木齐市、乌苏市、呼图壁县生态环境质量良好，沙湾县、石河子市、奎屯市、玛纳斯县生态环境质量一般，米泉市、阜康市、克拉玛依市、昌吉市生态环境质量较差；良好、一般及差的县市区域面积分别占研究区面积的39．8％、27．89％和32．29％。这种生态环境质量分异特征主要是由自然环境条件、人类经济活动、土地利用方式决定的。     

京杭运河(苏北段)污染状况分析

利用近几年京杭运河苏北各河段的监测结果，分析了京杭运河苏北段的污染状况和主要污染物以及污染来源。结果表明，京杭运河苏北段水质状况整体较差，总体水质为Ⅳ类，主要污染物为无机氮和有机物，最后对污染问题提出治理对策。     

Application of the DPSIR framework to environmental degradation assessment in northern Ghana

In many communities in northern Ghana, the environment has been altered by complex natural and human driven forces with significant impact on the lives of their inhabitants. The need to formulate an improved, holistic and consistent methodological approach to assess the problem is critical for sustainable natural resource management. This paper examines the potential of the DPSIR environmental assessment framework utilizing GIS‐based participatory methodology in the assessment of environmental degradation in northern Ghana. Community truthing tools such as key informant interviews, focus group discussions, participant observation and participatory Geographical Information Systems (GIS) were employed as a means of soliciting societal responses integrated to conventional GIS spatial analysis to measure the indicators of the Driving force–Pressure–State–Impacts–Response (DPSIR) assessment framework. Post classification GIS imagery results show a marked natural vegetation decrease of 634 km2 (42%) of the study area with a corresponding increase of 600 km² (39%) of grasses and built‐up and barren environment in the period of 14 years from 1990 to 2004. This is attributed to extreme climatic conditions and human driven causes such as poverty, population growth, migration and land tenure system. Poverty reduction strategies, amendment of the Mining and Mineral Law (PNDC law 153), improvement of the existing land tenure system and the control of migrants and Fulani herdsmen from neighbouring Burkina Faso were some of the solutions selected by the research participants, to be emphasized in the National Environmental Action Plan (EPA Act 490). This paper concludes that the DPSIR environmental assessment framework is an effective means of organizing complex environmental information to facilitate policy decision making.