新优草本地被植物在湖南引种初报

该研究在对湖南省及省外草本地被植物应用调查研究的基础上,引进10种草本地被植物,通过观察其在引入地的形态特征、物候期及生态适应性,初步筛选出6种具有推广潜质的品种,即瞿麦、紫娇花、绿苋草、血草、柳叶马鞭草、金叶苔草.旨在为我省基础绿化植物品种的选择提供理论参考,为增添我省植物多样性做出贡献.表3,参5.     

Effects of nutrient concentration and litter cover on quantitative shoot parameters and belowground biomass of Zizania latifolia (L)

This study investigated the effect of nutrient concentration and litter cover on the development of quantitative shoot parameters and belowground biomass (BGB) production of Zizania latifolia. Zizania latifolia is a common emergent aquatic species in East Asia. Four treatments were done at the study site, and were observed between May 2003 and December 2005. The treatments are namely, high nutrient (HN) with litter cover (HNWL), high nutrient without litter cover (HNNL), low nutrient (LN) with litter cover (LNWL), and low nutrient without litter cover (LNNL). The quantitative shoot parameters and BGB had higher values for treatments with high nutrient (HN) compared to the low nutrient treatments (LN), independent of the presence of litter cover. Furthermore, the life span of the secondary shoots was also higher in HN treatments compared to LN treatments. The BGB productivity was higher in the HNNL treatment compared to the other treatments. The LNWL treatment showed the least developed quantitative shoot parameters, e.g. plant height, and the lowest BGB for Z. latifolia. It was generally observed that the combined effects of low nutrients and litter cover negatively affected shoot development and BGB production.     

Effects of vegetation cover, presence of a native ant species, and human disturbance on colonization by Argentine ants

The spread of non-native invasive species is affected by human activity, vegetation cover, weather, and interaction with native species. We analyzed data from a 17-year study of the distribution of the non-native Argentine ant (Linepithema humile) and the native winter ant (Prenolepis imparis) in a preserve in northern California (U.S.A.). We conducted logistic regressions and used model selection to determine whether the following variables were associated with changes in the distribution of each species: presence of conspecifics at neighboring sites, distance to development (e.g., roads, buildings, and landscaped areas), proportion of vegetation cover taller than 0.75 m, elevation, distance to water, presence of both species at a site, temperature, and rainfall. Argentine ants colonized unoccupied sites from neighboring sites, but the probability of appearance and persistence decreased as distance to development, vegetation cover, and elevation increased. Winter ants appeared and persisted in sites with relatively high vegetation cover (i.e., highly shaded sites). Presence of the 2 species was negatively associated in sites with high vegetation cover (more winter ants) and sites near development (more Argentine ants). Probability of colonization of Argentine ants decreased where winter ants were most persistent. At sites near development within the preserve, abundant Argentine ant populations may be excluding winter ants. The high abundance of Argentine ants at these sites may be due to immigration from suburban areas outside the preserve, which are high-quality habitat for Argentine ants. In the interior of the preserve, distance from development, low-quality habitat, and interaction with winter ants may in combination exclude Argentine ants. Interactions among the variables we examined were associated with low probabilities of Argentine ant colonization in the preserve.     

基于DEM的山地丘陵区土地利用/覆被研究——以青海湖流域为例

研究地形对土地利用空间分布格局的影响,对探讨不同地貌部位自然因素和人文因素在土地利用变化过程中的作用具有重要意义。论文以青海湖流域为例,对比各土地利用类型的投影面积与地表真实面积的差异,并从地形(高程、坡度、坡向)角度分析了流域内土地利用的空间分布格局。结果表明:流域投影面积与地表真实面积相差754.79 km²。耕地、居民地、水域、沙地主要分布在3 500 m以下,且坡度小于2°的平地上,耕地和居民地多分布在南坡和西南坡上;林地主要分布在3 500~4 000 m且坡度多在6~25°的缓地和斜坡上,各坡向分布较均匀;草地主要分布在4 500 m以下且坡度小于25°的坡地上;沼泽多分布在3 500~4 500 m且坡度小于25°的河源地区,多分布在北坡和东北坡上;其它用地主要分布在4 000~4 500 m的坡度较大的斜坡或陡坡上。随高度、坡度增加,土地利用程度综合指数呈下降趋势;土地利用综合指数在坡向上呈现:平地＞阳坡＞阴坡。说明地形在很大程度上影响着青海湖流域的土地利用分布,且这种影响比较符合当地的自然规律和社会经济规律。     

基于环境一号卫星的太湖流域地表温度与地表类型的关系分析

利用我国新发射的环境一号小卫星数据,以2010年3月26日环境一号卫星的红外波段为例,尝试根据同步MODIS数据反演大气水汽含量参数,采用Jimenez-Munoz和Sobrino的普适性单通道算法反演地表温度,经MODIS地表温度产品验证,地表温度反演精度满足要求. 将人工目视解译的2009年太湖流域土地利用、地表温度和归一化植被指数作相关性分析. 结果表明:当林地和农田、草地植被指数相同时,林地的地表温度比农田和草地低,因此林地比农田和草地的调节温度效果好,在城市中增加林地的面积,对缓解城市热岛效应的作用最大.      

生活垃圾填埋场春夏季CH4释放及影响因素

采用静态箱法监测了2个生活垃圾填埋场春、夏季及昼夜的CH₄释放通量,并分析了影响CH₄释放的相关因素. 结果表明:填埋气体(LFG)主动收集对填埋场CH₄释放的影响显著. 在填埋龄相近的条件(4.0～4.5年)下,无LFG主动收集的填埋场春、夏季CH₄的释放通量(以CH₄计)平均值〔(541±1　005) mg/(m2·h)〕比有LFG主动收集的填埋场提高4.4倍. 在有LFG主动收集的填埋场内,填埋龄为1.0～1.5年的非渗滤液灌溉区的CH₄释放通量均值〔(324±847)mg/(m2·h)〕为灌溉区的10.0倍左右. 在有LFG主动收集的填埋场内,CH₄释放通量与各环境因子间无显著相关;而在无LFG主动收集的填埋场内,CH₄释放通量分别与覆土温度和气温呈显著正相关,与大气压强呈显著负相关.相关性分析结果表明,CH₄释放通量与填埋场覆土中含水率,w(有机碳)和w(总氮)呈显著正相关.      

Temporal-spatial dynamics of vegetation variation on non-point source nutrient pollution

The temporal-spatial interaction of land cover and non-point source (NPS) nutrient pollution were analyzed with the Soil and Water Assessment Tool (SWAT) to simulate the temporal-spatial features of NPS nutrient loading in the upper stream of the Yellow River catchment. The corresponding land cover data variance was expressed by the normalized difference vegetation index (NDVI) that was calculated from MODIS images. It was noted that the temporal variation of land cover NDVI was significantly correlated with NPS nutrient loading. The regression analysis indicated that vegetation not only detained NPS nutrient pollution transportation, but also contributed to sustainable loading. The temporal analysis also confirmed that regional NDVI was an effective index for monthly assessment of NPS nitrogen and phosphorus loading. The spatial variations of NPS nutrient loading can be classified with land cover status. The high loadings of NPS nitrogen in high NDVI subbasins indicated that forestry and farmland are the main critical loss areas. Farmland contributed sustainable soluble N, but the loading of soluble and organic N from grassland subbasins was much lower. Most P loading came from the areas covered with dense grassland and forestry, which cannot directly discharge to local water bodies. However, some NPS phosphorus from suburban farmland can directly discharge into adjacent water bodies. The interactions among nutrient loading, NDVI, and slope were also analyzed. This study confirmed that the integration of NPS modeling, geographic information systems, and remote sensing is needed to understand the interactive dynamics of NPS nutrient loading. Understanding the temporal-spatial variation of NPS nutrients and their correlations with land cover will help NPS pollution prevention and water quality management efforts. Therefore, the proposed method for evaluating NPS nutrient loading by land cover NDVI can be an effective tool for pollution evaluation and watersheds planning.     

鄂尔多斯高原沙地草地荒漠化景观现状的定量分析

基于相互垂直的2条5km长的样线的野外调查,分析了鄂尔多斯高原东南部地区沙地草地的景观现状.对2条样线上的斑块出现的频度的统计分析表明,该地区景观以小尺度斑块为主,有95%以上的斑块直径小于50m,平均斑块直径只有15m,但仍有较大面积的流沙斑块存在.对沿样线的裸地百分比盖度的半方差分析揭示了该区域荒漠化景观依赖于空间尺度的环境异质性,所调查的沿样线裸地百分比盖度的分维,接近于2,说明其空间异质性主要集中在较小的尺度上.这说明该区景观较为稳定,但沙化面积有扩大的趋势.     

1982—2006年中国半干旱、干旱区气候与植被覆盖的时空变化

利用1982-2006年英国CRU(Climatic Research Unit)全球气温降水数据和NOAA/NASA归一化植被指数(theNormalized Difference Vegetation Index,NDVI)数据,分析了中国内陆半干旱和干旱区的气候、植被覆盖的时空变化。结果表明,虽然中国内陆半干旱和干旱区的部分区域降水减少,但整体上向暖湿化发展。在暖湿化背景下,中国内陆半干旱和干旱区的植被总体以改善为主(>1%.(10a)-1),特别是新疆西北部和青海东南部;但局部有微弱的减少趋势[(0~-1)%.(10a)-1],如新疆南部和东部、甘肃西北部。最后,以乌鲁木齐为例,分析发现气温增加导致植被生长季延长和降水的增加,使得过去25年乌鲁木齐的植被覆盖有明显的改善。     

黑河流域下游水分驱动下的生态演化

在 GIS 技术支持下,以地下水数值模拟模型为依托,分析了地下水埋深对植被群落(草地、有林地、疏林地和灌木林)盖度的影响,剖析了水源距离对景观变化的影响.结果表明,在一定的地下水埋深范围内,天然植被群落盖度与地下水埋深之间有着较显著的 LOGSTIC 关系(“S”型曲线),且草地植被群落盖度对地下水埋深变化的响应程度最大.从水源距离对景观空间分异的影响来看,随着水源距离的增加,非荒漠景观的分布面积比例逐渐减小.水源距离对景观动态也有着显著的影响.