鄱阳湖湿地灰化苔草种群生产力特征及其水文响应

淡水湖泊湿地中,水文条件是影响湿地植物分布和生长发育的关键因素,研究特定湿地植物种群与水文变化之间关系,对于认识湿地植被格局形成及进行湿地生态调控与恢复具有重要意义。选取鄱阳湖湿地洲滩优势植物——灰化苔草(Carex cinerascens)种群作为研究对象,基于野外实地观测数据,研究不同高程带灰化苔草春草种群生产力特征及其对水文变化的响应。结果表明:春草生长季内各高程带灰化苔草种群变化规律基本一致,但其生长发育过程对水文条件产生差异性反应,长期连续水淹和半水淹条件抑制灰化苔草的生长,而间歇性半水淹和未水淹条件则促进灰化苔草伸长生长和生物量积累;生长初期灰化苔草通过储水策略应对水分缺乏形成的干旱胁迫,而生长末期则通过增加干物质含量来应对淹水胁迫;灰化苔草定植与生长发育需要一定的水文条件,淹没期平均水深3.70—2.78 m、淹没频率42.08%—43.17%、平均距湖水面高度-0.23—0.77 m的水文环境更有利于灰化苔草的生长发育。研究结果可为未来鄱阳湖湿地植被保护和湖泊水位调控提供重要参考依据。     

基于SWAT的西北干旱区县域水文模拟——以临泽县为例

以西北干旱区的临泽县为例,利用1980—2012年的气象数据、土地利用数据、土壤数据、数字高程数据驱动SWAT模型,对县域水文过程进行了模拟并对行政区内的水资源状况进行了时空特征分析。研究表明临泽县1980—2012年均实际蒸发量、下渗量、壤中流补给量、地下水补给量、产流量、可用地表水资源量和产流系数分别为130.53、49.78、68.95、48.00、53.47 mm、(13.17±0.60)×108m3和0.16;生态用水量大(3.56±0.12)×1011m3),且呈现出增加趋势。由于黑河分水措施的影响,各水量要素的突变年份出现在2000年之后的5年内。从空间分布上看,地下水补给量和产流系数都呈现“南高北低”的趋势。研究结果也表明临泽县1980—2012年的产流量由地下水补给量控制,壤中流和地下径流的贡献分别为43%和57%;而可利用水资源量主要依赖上游的来水,上游来水量的贡献率达到83%。此外,我们的研究也发现临泽县2007—2012的实际蒸发持续增加,从而导致“蒸发悖论”现象的存在。     

Macroinvertebrates on Eichhornia crassipes roots in two lakes of the Paraná River floodplain

Changes in the abundance, biomass and in the relativeproportions of functional feeding groups ofmacroinvertebrates were studied for 17 months duringlow and high water periods in two floodplain lakeswith indirect connections to the Paraná River.At low water, Eichhornia crassipes root clusterswere colonized by comparatively low densities ofmacroinvertebrates, especially in the lake moredistant to the river. Collector-gatherers andpredators were the most abundant functional feedinggroups, but different taxa of these groups dominatedin the two lakes during low water.At high water, macroinvertebrates densities increasedas a result of increased flow through the roots. Inthis period, collector-filterers dominated at bothlakes and constituted over 34% of themacroinvertebrates. Four independent variables(conductivity, hydrological periods, dissolved oxygenand site) explain 87% of the variability inmacroinvertebrates density expressed as the number ofindividuals per m2. No significant relationshipwere found between macroinvertebrate biomass and anyof the independent variables.     

Trade-offs between water yield and carbon sequestration for sub-alpine catchments in western Sichuan,China

Aims There is increasing concern on the trade-off between carbon sequestration and water yield of forest ecosystems. Our objective was to explore the effects of vegetation composition on water and carbon trade-off in the sub-alpine watersheds of western Sichuan during 1982-2006.Methods The WaSSI-C, which is an eco-hydrological model with coupled water and carbon cycles, was employed to calculate the key components in water balance and carbon sequestration for the 22 sub-catchments in the upper reaches of Zagunao River. Spearman’s Rho trend analysis was used to examine the trends in runoff and net ecosystem productivity. Important findings Compared with either subalpine meadow or mixed forest dominated catchments, the conifer-dominated catchments had much higher water loss due to high evapotranspiration, and the loss was not offset by its higher soil water infiltration during the growing season. The change in soil water storage for subalpine meadow, mixed forest and coniferous forest are -44 mm, -18 mm and -5 mm, respectively, which indicated significant decline in soil water storage and thus water yield particularly in alpine meadow catchments. Significant negative relationship was found between runoff and net ecosystem productivity, the alpine meadow as the dominant vegetation type showed high water yield and low carbon sequestration, and the conifer-dominant and mixed forest vegetation showed low water yield and high carbon sequestration, moreover, the higher the forest coverage, the lower the water yield. Upward trends in net ecosystem productivity were observed in the three vegetation types during the study period and the alpine meadow type was significant.     

森林管理的生态效应研究进展

森林管理是实现森林生产效益最大化的主要措施，是增加碳吸收以减缓气候变暖的关键手段，是调节区域水文循环的有效途径，是保护地以外实现生物多样性保护目标的重要补充。然而，追求单一生产功能的传统森林管理弱化了其他生态功能，并对森林景观结构和生物多样性产生负面影响。全球80%以上森林由于人类活动呈现不同程度退化进而影响人类福祉，森林管理需要优化以追求多维生态功能的协同共赢。当前，对于森林管理的生态效应仍有较多争论或未形成明确认识，可持续森林管理能否取得额外的气候效益仍有待确认，森林管理如何影响不同区域的水文生态功能仍未形成明确认识，不同类型森林管理或多或少、或正面或负面影响栖息地及不同种类生物多样性的强度和方向不明确。因此，森林管理的生态效应是一个值得深入探索的问题，未来需要深入量化不同管理措施对气候变化缓解、水文循环调节、生物多样性保护乃至提供其他生态功能的作用，将维持或提升生态功能及生物多样性作为可持续森林管理的一个重要目标，通过优化森林管理策略开展森林提质增效以获得最大收益。     

Risks of pesticides to groundwater ecosystems

The current standard for pesticides in groundwater in the Netherlands is the same as that for drinking water: a maximum of 0.1 μg per liter for each individual pesticide and a maximum of 0.5 μg per liter for all agents collectively. This standard applies to water located at least ten meters below ground level. It is based on an old detection limit, which is out of date by now, and on the view that drinking water should be entirely free of pesticides. Recently, however, there are increasing calls for a system of standards underpinned by toxicological data. A committee of the Health Council of the Netherlands (please see note at the end of this article) has dealt with the question whether, apart from human health criteria, ecotoxicological criteria should be taken into consideration when evaluating the risks posed by pesticides in groundwater. This paper closely follows the executive summary of her report     

Indirect and direct controls of macroinvertebrates and small fish by abiotic factors and trophic interactions in the Florida Everglades

1. The roles of nutrients, disturbance and predation in regulating consumer densities have long been of interest, but their indirect effects have rarely been quantified in wetland ecosystems. The Florida Everglades contains gradients of hydrological disturbance (marsh drying) and nutrient enrichment (phosphorus), often correlated with densities of macroinvertebrate infauna (macroinvertebrates inhabiting periphyton), small fish and larger invertebrates, such as snails, grass shrimp, insects and crayfish. However, most causal relationships have yet to be quantified. 2. We sampled periphyton (content and community structure) and consumer (small omnivores, carnivores and herbivores, and infaunal macroinvertebrates inhabiting periphyton) density at 28 sites spanning a range of hydrological and nutrient conditions and compared our data to seven a priori structural equation models. 3. The best model included bottom‐up and top‐down effects among trophic groups and supported top‐down control of infauna by omnivores and predators that cascaded to periphyton biomass. The next best model included bottom‐up paths only and allowed direct effects of periphyton on omnivore density. Both models suggested a positive relationship between small herbivores and small omnivores, indicating that predation was unable to limit herbivore numbers. Total effects of time following flooding were negative for all three consumer groups even when both preferred models suggested positive direct effects for some groups. Total effects of nutrient levels (phosphorus) were positive for consumers and generally larger than those of hydrological disturbance and were mediated by changes in periphyton content. 4. Our findings provide quantitative support for indirect effects of nutrient enrichment on consumers, and the importance of both algal community structure and periphyton biomass to Everglades food webs. Evidence for top‐down control of infauna by omnivores was noted, though without substantially greater support than a competing bottom‐up‐only model.     

基于矩阵分析的水文调节服务供需关系时空分异研究——以嘉兴市为例

生态系统服务供需关系的识别、度量、空间化分析对自然资源合理配置有重要的意义。以嘉兴市为研究区,以2005年Landsat7 ETM+影像和2015年Landsat8 OLI传感器影像为数据源,采用生态系统服务供需关系矩阵法,分析嘉兴市水文调节服务供给能力与需求水平的时空分异特征。结果表明:(1)2005—2015年10年间,嘉兴市处于快速城市化阶段,土地利用变化明显,建设用地显著增加,水域、水田面积有所增加,旱地、园地、林地大量减少。(2)土地利用变化是影响水文调节服务供需关系的主要因素,研究发现嘉兴市大部分地区水文调节服务处于供不应求的状态。(3)随着建设用地的不断扩张,导致水文调节服务供需矛盾加剧,供不应求区域由中心城区向城市边缘区扩大。(4)水文调节服务需求区域的变化与人类活动密切相关,供给区域受制于自然环境的数量与质量,生态系统服务供给与需求存在错位,促进了生态系统服务流的产生,并需要政策引导。