Framework and Tools for Agricultural Landscape Assessment Relating to Water Quality Protection

While many scientific studies show the influence of agricultural landscape patterns on water cycle and water quality, only a few of these have proposed scientifically based and operational methods to improve water management. Territ’eau is a framework developed to adapt agricultural landscapes to water quality protection, using components such as farmers’ fields, seminatural areas, and human infrastructures, which can act as sources, sinks, or buffers on water quality. This framework allows us to delimit active areas contributing to water quality, defined by the following three characteristics: (i) the dominant hydrological processes and their flow pathways, (ii) the characteristics of each considered pollutant, and (iii) the main landscape features. These areas are delineated by analyzing the flow connectivity from the stream to the croplands, by assessing the buffer functions of seminatural areas according to their flow pathways. Hence, this framework allows us to identify functional seminatural areas in terms of water quality and assess their limits and functions; it helps in proposing different approaches for changing agricultural landscape, acting on agricultural practices or systems, and/or conserving or rebuilding seminatural areas in controversial landscapes. Finally, it allows us to objectivize the functions of the landscape components, for adapting these components to new environmental constraints.     

Effects of Invasive Plants on Arthropods

Non‐native plants have invaded nearly all ecosystems and represent a major component of global ecological change. Plant invasions frequently change the composition and structure of vegetation communities, which can alter animal communities and ecosystem processes. We reviewed 87 articles published in the peer‐reviewed literature to evaluate responses of arthropod communities and functional groups to non‐native invasive plants. Total abundance of arthropods decreased in 62% of studies and increased in 15%. Taxonomic richness decreased in 48% of studies and increased in 13%. Herbivorous arthropods decreased in response to plant invasions in 48% of studies and increased in 17%, likely due to direct effects of decreased plant diversity. Predaceous arthropods decreased in response to invasive plants in 44% of studies, which may reflect indirect effects due to reductions in prey. Twenty‐two percent of studies documented increases in predators, which may reflect changes in vegetation structure that improved mobility, survival, or web‐building for these species. Detritivores increased in 67% of studies, likely in response to increased litter and decaying vegetation; no studies documented decreased abundance in this functional group. Although many researchers have examined effects of plant invasions on arthropods, sizeable information gaps remain, specifically regarding how invasive plants influence habitat and dietary requirements. Beyond this, the ability to predict changes in arthropod populations and communities associated with plant invasions could be improved by adopting a more functional and mechanistic approach. Understanding responses of arthropods to invasive plants will critically inform conservation of virtually all biodiversity and ecological processes because so many organisms depend on arthropods as prey or for their functional roles, including pollination, seed dispersal, and decomposition. Given their short generation times and ability to respond rapidly to ecological change, arthropods may be ideal targets for restoration and conservation activities. Efectos de las Plantas Invasoras sobre los Artrópodos     

Global information sampling in the honey bee

Central to the question of task allocation in social insects is how workers acquire information. Patrolling is a curious behavior in which bees meander over the face of the comb inspecting cells. Several authors have suggested it allows bees to collect global information, but this has never been formally evaluated. This study explores this hypothesis by answering three questions. First, do bees gather information in a consistent manner as they patrol? Second, do they move far enough to get a sense of task demand in distant areas of the nest? And third, is patrolling a commonly performed task? Focal animal observations were used to address the first two predictions, while a scan sampling study was used to address the third. The results were affirmative for each question. While patrolling, workers collected information by performing periodic clusters of cell inspections. Patrolling bees not only traveled far enough to frequently change work zone; they often visited every part of the nest. Finally, the majority of the bees in the middle-age caste were shown to move throughout the nest over the course of a few hours in a manner suggestive of patrolling. Global information collection is contrary to much current theory, which assumes that workers respond to local information only. This study thus highlights the nonmutually exclusive nature of various information collection regimes in social insects.     

水质基准本土环节动物与水生昆虫受试生物筛选

作为水环境质量评价体系中重要的指示生物类别,水生环节动物和水生昆虫是水生生物基准研究中不可或缺的基准受试生物.参照美国水生生物基准技术指南, 选择我国广泛分布的10种本土环节动物和水生昆虫,搜集、筛选对各水生物种毒性最大的3种污染物,并进行水生生物敏感性分析. 在污染物毒性数据的物种敏感度分布中,若物种的累积概率小于30%则为较敏感,该物种可作为基准研究受试生物. 结果表明:不同生物对污染物敏感性存在差异,颤蚓对有机锡化合物、重金属,苏氏尾鳃蚓对重金属均较敏感;仙女虫、黄翅蜻、四节蜉、扁蜉对各类农药均较敏感;尾盘虫能够在一定程度上指示表面活性剂污染状况. 因此,环节动物颤蚓属、尾鳃蚓属、尾盘虫属、仙女虫属,水生昆虫黄翅蜻属、四节蜉属及扁蜉属均可作为水质基准研究中的受试生物.      

Identifying Linkages Between Land Use,Geomorphology, and Aquatic Habitat in a Mixed-Use Watershed

The potential impacts of land use on large woody debris (LWD) were examined in Sourdough Creek Watershed, a rapidly growing area encompassing Bozeman, Montana, USA. We identified six land classes within a 250 m buffer extending on either side of Sourdough Creek and assessed aquatic habitat and geomorphologic variables within each class. All LWD pieces were counted, and we examined 14 other variables, including undercut bank, sinuosity, and substrate composition. LWD numbers were generally low and ranged from 0 to 8.2 pieces per 50 m of stream. Linear regression showed that LWD increased with distance from headwaters, riparian forest width, and sinuosity in four of the six land classes. Statistically significant differences between land classes for many aquatic habitat and geomorphologic variables indicated the impacts of different land uses on stream structure. We also found that practices such as active wood removal played a key role in LWD abundance. This finding suggests that managers should prioritize public education and outreach concerning the importance of in-stream wood, especially in mixed-use watersheds where wood is removed for either aesthetic reasons or to prevent stream flooding.     

Cumulative Industrial Activity Alters Lotic Fish Assemblages in Two Boreal Forest Watersheds of Alberta,Canada

We evaluated the cumulative effects of land use disturbance resulting from forest harvesting, and exploration and extraction of oil and gas resources on the occurrence and structure of stream fish assemblages in the Kakwa and Simonette watersheds in Alberta, Canada. Logistic regression models showed that the occurrence of numerically dominant species in both watersheds was related to two metrics defining industrial activity (i.e., percent disturbance and road density), in addition to stream wetted width, elevation, reach slope, and percent fines. Occurrences of bull trout, slimy sculpin, and white sucker were negatively related to percent disturbance and that of Arctic grayling, and mountain whitefish were positively related to percent disturbance and road density. Assessments of individual sites showed that 76% of the 74 and 46 test sites in the Kakwa and Simonette watersheds were possibly impaired or impaired. Impaired sites in the Kakwa Watershed supported lower densities of bull trout, mountain whitefish, and rainbow trout, but higher densities of Arctic grayling compared to appropriate reference sites. Impaired sites in the Simonette Watershed supported lower densities of bull trout, but higher densities of lake chub compared to reference sites. Our data suggest that current levels of land use disturbance alters the occurrence and structure of stream fish assemblages.     

Circulation and Stream Plume Modeling in Conesus Lake

A three-dimensional hydrodynamic model that includes the effect of drag from macrophytes was applied to Conesus Lake to study the seasonal circulation and thermal structure during spring and early summer. Local weather conditions and stream flow data were used to drive the model. The drag coefficient for macrophytes was calculated as a function of leaf density. In general, the model results show good agreements with the observations, including vertical temperature profiles measured at two locations and average surface temperature derived from calibrated thermal imagery for large-scale simulations of the entire lake. Additional high-resolution simulations were carried out to understand water circulation and transport of sediment and model-generated tracer during hydrometeorological events at stream mouths for two experimental sites. The model results show that the plume development at stream mouths during storm events in Conesus Lake are site-dependent and may either be current- or wind-driven. The results also show a significant effect from the presence of macrophytes on sediment deposition near stream mouths.     

不同土地利用对溪流大型底栖无脊椎动物群落的影响

2010年4月调查了钱塘江中游区域29个样点的水环境特征和底栖动物。聚类排序将样点分为参照、农业和城镇3组,相似性分析表明不同组间底栖动物群落有显著差异(r=0.863,P=0.001)。环境因子的主成分分析表明,研究区域主要的环境胁迫是农业和城镇用地及其引起的水质变化,并能较好解释组间物种差异的关键环境胁迫因子为农业用地比例、城镇用地比例、溶解氧、总氮和平均底质得分(Rho=0.568,P=0.001)。底栖动物参数(总分类单元数、Shannon-Weaver多样性指数、BI指数和丰富度指数)和k-优势度曲线显示农业和城镇组的生物完整性遭到很大程度的破坏,且农业组较城镇组严重。     

Forest clearing and sex ratio in forest-dwelling wood ant <Emphasis Type="Italic">Formica aquilonia</Emphasis>

Sex ratios of ants have been shown to vary with food resource levels in several studies, but it is not known whether forest clear-cutting has any effect on sex ratio of aphid-tending forest-dwelling ants. We investigated whether the offspring sex ratio of the forest dwelling ant Formica aquilonia varied as a response to clear-cutting. We found that the proportion of males was smaller in clear-cuts than in adjacent forests. Our results are among the first showing that anthropogenic changes in forest structures may have a potential to modify sex ratios of social insects and other forest-dwelling animals.     

Forest health conditions in North America

Some of the greatest forest health impacts in North America are caused by invasive forest insects and pathogens (e.g., emerald ash borer and sudden oak death in the US), by severe outbreaks of native pests (e.g., mountain pine beetle in Canada), and fires exacerbated by changing climate. Ozone and N and S pollutants continue to impact the health of forests in several regions of North America. Long-term monitoring of forest health indicators has facilitated the assessment of forest health and sustainability in North America. By linking a nationwide network of forest health plots with the more extensive forest inventory, forest health experts in the US have evaluated current trends for major forest health indicators and developed assessments of future risks. Canada and Mexico currently lack nationwide networks of forest health plots. Development and expansion of these networks is critical to effective assessment of future forest health impacts.