Biotelemetry of crustacean decapods: sampling design,statistical analysis,and interpretation of data

Lotic systems in many regions of the country have experienced habitat degradation and biodiversity loss due to agricultural activity and urbanization. Southeastern Michigan is no exception, as agriculture in the River Raisin watershed and increased urbanization in the Huron River watershed threatens both systems. To further understand the ecological impact of land use on trophic interactions in Midwestern streams and assess the use of a selected set of weighted, quantitative food web metrics as a tool for investigating the influence of anthropogenic disturbance on these systems we compared summer food webs for nine second-order streams. All streams were categorized as developed, undeveloped, or agricultural based on land cover data. Developed and undeveloped streams were located in the Huron River watershed and agricultural streams were located in the River Raisin watershed. Reach-level habitat quality was also assessed at each study site using the EPA’s Rapid Habitat Assessment. Fish diets (n = 410) were analyzed to create summer food webs for each site. Comparisons of food webs were made using a suite of weighted, quantitative metrics to identify differences in fish–macroinvertebrate interactions across streams with differing land cover at the sub-basin scale and habitat quality at the local scale. Although undeveloped streams had higher species richness and less habitat degradation, no significant patterns were observed in the quantitative metrics across the three stream categories or based on reach-level habitat conditions. Decapoda, terrestrial Hymenoptera, and Chironomidae were the primary prey taxa in all stream categories. Decapods accounted for the majority of biomass consumed and the pattern of this consumption strongly influenced metric scores. The suite of quantitative metrics tested in this study did not detect significant differences in fish–macroinvertebrate food webs across land use categories, likely in part due to the dominance of a large, tolerant prey taxa in fish diets, regardless of land use and local habitat quality.     

Continuity and Distinction in Land Cover Across a Rural Stretch of the U.S.-Mexico Border

Differences in land use and land cover often coincide with social and political borders. Using vegetation indices and a visual inspection of Landsat imagery, we consider a rural section of the central Arizona-Sonora border dominated by government-owned land on the U.S. side and seek to understand where and why cross-border land cover continuity exists in some places while distinction exists in others. Land cover distinctions are attributed largely to differential population and economic pressures in the two countries, but are also exacerbated by social and political distinctions. By contrast, historical relations, common use of the land, and relative remoteness provide cross-border homogeneity in land use and land cover in rural areas, especially on the Tohono O’odham reservation.     

岷江上游土地利用/覆被变化及其驱动力

岷江上游具有自然环境的复杂性、生态系统的脆弱性、经济发展的边缘性、社会文化的过渡性等特性,其土地利用/土地覆盖变化的特点可以代表我国西南山地土地资源及利用中所存在的普遍问题.林地和草地是岷江上游地区的主要土地利用类型.从1974～2000年间各个土地利用类型均发生了不同程度的变化,林地面积持续减少,其它类型面积均有不同程度的增加.类型间的面积变化均为双向,主要发生在有林地、灌木林地、经济林地、草地、居民用地和耕地之间,且主要在林地和草地两个类型之间.其中1974～1986年的变化大于1986~2000年.人口和经济是该区土地利用变化的主要驱动因素.自实施天然林保护工程和退耕还林还草工程以来,该区土地利用状况有所好转,正在向好的方向发展.     

东江流域景观格局演变分析及变化预测

以东江流域土地利用解译结果为基础,采用转移矩阵、移动窗口法和景观格局指数对1990—2016年对东江流域的景观格局时空变化进行分析,并结合地形因子、交通通达度因子和限制转化因子采用FLUS(Future Land Use Simulation)模型对流域未来景观格局进行预测。结果表明:(1)自1990年以来,研究区的7种土地利用类型皆发生了变化,其中建设用地由于林地和耕地的大量转入增加最明显。(2)1990—2016年,流域景观破碎化呈现以河道为中心向东西两侧减小的趋势,景观多样性呈现流域上游小,下游大的趋势,且高值区在经济较发达的城镇地区。园地的景观破碎程度最高、林地的优势度减弱,城镇建设用地的集聚度增加。(3)2016—2042年,流域各用地类型变化率不大,景观破碎化和多样性程度虽有增加但增长速度相对放缓。     

基于土地利用变化的京津冀生境质量时空演变

土地利用变化是全球变化的核心内容,评估土地利用变化引起的生境质量时空分异性是区域生态规划的基础,能为土地利用规划和土地管理政策制定提供科学依据.本文在分析京津冀2000—2010年土地利用变化的基础上,以InVEST模型对生境质量进行总体评估,并基于流域划分,借助剖面线和空间自相关深入分析了生境质量格局时空分异性.结果表明：2000—2010年,研究区主要土地利用变化类型为：耕地转为建设用地、林地和草地间的相互转换及水体转为耕地,这导致景观结构异质性的减弱和破碎度的提升.两时期生境质量格局整体表现为东南部和南部较低、北部和西部较高.其中,东南部和南部2010年生境质量明显下降,发生了一定生境退化乃至丧失现象.各流域生境质量具有明显分段特征,较多样点在2010年出现不同程度退化,但也有部分有所改善.该区生境质量格局空间分布集聚性有所增强.2000年“高高”型生境质量流域空间聚集区为滦河流域和白河流域上游地区,“低低”型聚集区集中在永定河中下游和潮白河流域部分地区.2010年“高高”型和“低低”型空间聚集区在原有基础上各自向西南方向有所扩展.     

基于Google Earth Engine平台与复杂网络的黄河流域土地利用/覆被变化分析

黄河流域在中国社会经济发展和生态安全方面的地位十分重要,过去几十年的自然演变和人类活动对其造成了深远影响,系统科学地认识黄河流域的环境格局变化是实现黄河流域高质量发展的重要前提。基于Google Earth Engine平台和复杂网络分析方法,解译并分析了1986年至2018年黄河流域的连续年度土地利用/覆被变化(LUCC)。基于1000个独立验证点进行的评估显示解译的覆盖黄河流域33年的年度土地利用/覆被数据集的7个一级类的总体准确率为82.6%,15个二级类的总体准确率为74.7%。分析结果显示黄河流域的土地系统在整个研究期间呈现出复杂的时空变化,主要的LUCC模式包括：不变或很小的变化、伴随耕地流失的城市扩张、草地恢复、果园和梯田扩张和森林增加。基于复杂网络方法对黄河流域土地系统的分析表明,土地利用/覆被转移网络中的高覆盖草地、低植被覆盖地表和落叶常绿混交林与其他地类的转移较频繁,地类节点的中介中心性和度值较高,是黄河流域土地系统中的关键地类。另外与人类活动关系密切的果园和梯田、谷物耕地和城市及建设用地节点组成了较为活跃的网络社区结构,它们都有较高的结构多样性、接近中心性,这些地...     

Remotely-sensed indicators for monitoring the general condition of “natural habitat” in watersheds: an application for Delaware’s Nanticoke River watershed

Over the past two decades there has been increasing interest in developing indicators to monitor environmental change. Remote sensing techniques have been primarily used to generate information on land use/land cover changes. The US Fish and Wildlife Service has used this technology to monitor wetland trends and recently developed a set of remotely-sensed indicators to characterize and assess trends in the integrity of natural habitat in watersheds. The indices largely focus on the extent of “natural” cover throughout a given watershed, with an emphasis on locations important to fish, wildlife, and water quality. Six indices address natural habitat extent and four deal with human-caused disturbance. A composite index of natural habitat integrity combining the habitat extent and habitat disturbance indices may be formulated to provide an overall numeric value for a watershed or subbasin. These indices facilitate comparison between watersheds (and subbasins) and assesssment of trends useful for environmental monitoring. This paper describes the indices and presents an example of their application for characterizing and assessing conditions of subbasins within Delaware’s Nanticoke River watershed.     

不同土地利用/覆被情景下生态系统减轻水库泥沙淤积的服务能力与经济价值模拟

以ArcGIS9.2为平台,构建了生态系统减轻水库泥沙淤积服务物质量和价值量评估模型.整合2000年的相关数据将此模型应用于二滩水库,并模拟了10种不同土地利用/覆被情景下集水区生态系统该项服务的能力和在水库使用年限内服务总价值的响应.结果表明:2000年,二滩水库集水区土壤保持量12.1亿t·a-1,高值区分布于雅砻江干流和支流水网附近.泥沙输移比在河道附近和水库周边较高.水库周边是最为主要的保沙区.水库使用年限内,集水区对于减轻二滩水库泥沙淤积服务总价值27.53亿元.集水区内不同结构类型的土地利用/覆被情景对保沙能力所产生的影响各异,模拟保沙量符合林地＞草地＞裸地＞农田规律,农田保沙能力最弱,是二滩水库最为主要的产沙源.     

Denitrification in the river network of a mixed land use watershed: unpacking the complexities

River networks have the potential to permanently remove nitrogen through denitrification. Few studies have measured denitrification rates within an entire river network or assessed how land use affect rates at larger spatial scales. We sampled 108 sites throughout the network of the Fox River watershed, Wisconsin, to determine if land use influence sediment denitrification rates, and to identify zones of elevated sediment denitrification rates (hot spots) within the river network. Partial least squares regression models identified variables from four levels of organization (river bed sediment, water column, riparian zone, and watershed) that best predicted denitrification rates throughout the river network. Nitrate availability was the most important predictor of denitrification rates, while land cover was not always a good predictor of local-scale nitrate concentrations. Thus, land cover and denitrification rate were not strongly related across the Fox River watershed. A direct relationship between denitrification rate and watershed land cover occurred only in the Wolf River sub-watershed, the least anthropogenically disturbed of the sub-watersheds. Denitrification hot spots were located throughout the river network, regardless of watershed land use, with hot spot location being determined primarily by nitrate availability. In the Fox River watershed, when nitrate was abundant, river bed sediment character influenced denitrification rate, with higher denitrification rates at sites with fine, organic sediments. These findings suggest that denitrification occurring throughout an entire river network, from headwater streams to larger rivers, can help reduce nitrogen loads to downstream water bodies.

     

Assessing land cover change in Kenya's Mau Forest region using remotely sensed data

Kenya's Rift Valley has been undergoing rapid land cover change for the past two decades, which has resulted in ecological and hydrological changes. An effort is under way to quantify the timing and rate of these changes in and around the River Njoro watershed located near the towns of Njoro and Nakuru using remote sensing and geographic information system (GIS) methods. Three Landsat TM images, representing a 17‐year period from 1986 to 2003 in which the area underwent a significant land cover transition, were classified and compared with one another. Vegetation diversity and temporal variability, common to tropical and sub‐tropical areas, posed several challenges in disaggregating classified data into sub‐classes. An iterative approach for the resolving challenges is presented that incorporates unsupervised and supervised classification routines in coordination with knowledge‐based spatial analyses. Changes are analysed at three spatial scales ranging from the highly impacted and deforested uplands to the watershed and landscape scales. Land cover transitions primarily occurred after 1995, and included large forest losses coupled with increases in mixed small‐scale agriculture and managed pastures and degraded areas. These changes in cover type are highly spatially variable and are theorized to have significant impacts on ecological and hydrologic systems with implications for environmental sustainability.     

1960—2008年阿克苏河流域生态系统服务价值动态

基于遥感与GIS技术,运用中国陆地生态系统服务价值当量表,结合当地粮食产量与粮食平均收购价格,分析了1960—2008年阿克苏河流域生态系统服务价值的变化,探讨了干旱区跨境河流流域生态系统服务变化对土地利用/覆被变化(LUCC)的响应.结果表明:研究期间,阿克苏河流域生态系统服务价值整体变化较小,总价值先减后增,沼泽、林地、草地面积的减少是总服务价值减少的主要原因,耕地和水域面积的增加补偿了总价值的部分损失,但损失略大于收益;各项生态功能的服务价值对总生态系统服务价值贡献大小的等级基本稳定,其中,土壤形成与保护和废物处理功能的贡献率最大;研究区生态系统服务价值大小及变化的空间差异较大,以流域下游的变化最频繁.敏感性分析表明,研究区内生态系统服务价值对服务价值指数缺乏弹性,研究结果具有稳健性.     

Natural regeneration as a tool for large‐scale forest restoration in the tropics: prospects and challenges

A major global effort to enable cost‐effective natural regeneration is needed to achieve ambitious forest and landscape restoration goals. Natural forest regeneration can potentially play a major role in large‐scale landscape restoration in tropical regions. Here, we focus on the conditions that favor natural regeneration within tropical forest landscapes. We illustrate cases where large‐scale natural regeneration followed forest clearing and non‐forest land use, and describe the social and ecological factors that drove these local forest transitions. The self‐organizing processes that create naturally regenerating forests and natural regeneration in planted forests promote local genetic adaptation, foster native species with known traditional uses, create spatial and temporal heterogeneity, and sustain local biodiversity and biotic interactions. These features confer greater ecosystem resilience in the face of future shocks and disturbances. We discuss economic, social, and legal issues that challenge natural regeneration in tropical landscapes. We conclude by suggesting ways to enable natural regeneration to become an effective tool for implementing large‐scale forest and landscape restoration. Major research and policy priorities include: identifying and modeling the ecological and economic conditions where natural regeneration is a viable and favorable land‐use option, developing monitoring protocols for natural regeneration that can be carried out by local communities, and developing enabling incentives, governance structures, and regulatory conditions that promote the stewardship of naturally regenerating forests. Aligning restoration goals and practices with natural regeneration can achieve the best possible outcome for achieving multiple social and environmental benefits at minimal cost.     

A Land System representation for global assessments and land‐use modeling

Current global scale land‐change models used for integrated assessments and climate modeling are based on classifications of land cover. However, land‐use management intensity and livestock keeping are also important aspects of land use, and are an integrated part of land systems. This article aims to classify, map, and to characterize Land Systems (LS) at a global scale and analyze the spatial determinants of these systems. Besides proposing such a classification, the article tests if global assessments can be based on globally uniform allocation rules. Land cover, livestock, and agricultural intensity data are used to map LS using a hierarchical classification method. Logistic regressions are used to analyze variation in spatial determinants of LS. The analysis of the spatial determinants of LS indicates strong associations between LS and a range of socioeconomic and biophysical indicators of human‐environment interactions. The set of identified spatial determinants of a LS differs among regions and scales, especially for (mosaic) cropland systems, grassland systems with livestock, and settlements. (Semi‐)Natural LS have more similar spatial determinants across regions and scales. Using LS in global models is expected to result in a more accurate representation of land use capturing important aspects of land systems and land architecture: the variation in land cover and the link between land‐use intensity and landscape composition. Because the set of most important spatial determinants of LS varies among regions and scales, land‐change models that include the human drivers of land change are best parameterized at sub‐global level, where similar biophysical, socioeconomic and cultural conditions prevail in the specific regions.     

黄土高原泾河流域长时间序列的归一化植被指数动态变化及其驱动因素分析

泾河流域土地开发历史悠久, 是黄土高原水土流失的典型区域。研究气候变化和人类活动影响下泾河流域的植被覆盖变化及其原因, 对黄土高原的植被恢复、水土保持和景观管理等都具有重要意义。该研究应用GIMMS归一化植被指数NDVI、土地覆盖分类数据和气候数据, 采用趋势分析和相关分析方法, 研究了泾河流域1982-2005年植被覆盖变化趋势及其驱动因素。研究表明: 泾河流域24年间79.64%的区域NDVI无显著变化趋势, NDVI趋势显著增加的区域占16.33%, 主要集中在流域中部和南部, NDVI趋势显著减小的区域占4.03%, 主要集中在流域北部。流域所有气象站点的降水量均无显著变化趋势, 气温均呈显著升高趋势。分析发现气候变化不能很好地解释NDVI趋势的空间分异, 人为因素更为重要。从土地利用分析结果来看, NDVI不同趋势下各土地利用类型比例无明显变化, 但NDVI显著增加区以耕地为主, 显著减小区以草地为主, 由此推断NDVI的显著增加趋势主要由耕地NDVI增加引起, 显著减小趋势可能与林地减少和草地退化有关。通过分析不同分区的土地利用数据和社会经济资料, 着重探讨了造成植被覆盖显著变化趋势的人为因素。     

流域景观格局与河流水质的多变量相关分析

流域内的景观格局改变是人类活动的宏观表现,会对河流水质产生显著影响,因此明确影响水质变化的关键景观因子,对于深入了解景观对水质的影响机制具有重要的研究价值。选择广东省淡水河流域为研究对象,以2007年ALOS卫星影像以及水质监测数据为基础,运用空间分析和多变量分析方法,分析淡水河流域景观格局与河流水质的相关关系。用包括流域和河岸带尺度的景观组成和空间结构信息的景观指数表征景观格局,用Spearman秩相关分析、多元线性逐步回归模型和典型相关分析(CCA)研究景观指数和水质指标的相关关系。研究结果表明:林地、城镇用地和农业用地占淡水河流域总面积超过90%,其中城镇用地超过20%。多元线性逐步回归分析和CCA结果说明水质指标受到多个景观指数的综合影响,反映了景观格局对水质的复杂影响机制。流域景观格局对河流水质有显著影响,流域尺度的景观指数比河岸带尺度的景观指数对水质影响更大。城镇用地比例是影响耗氧污染物和营养盐等污染物浓度最重要的景观指数,林地和农业用地对水质的影响较小。另外,景观破碎化对pH值、溶解氧和重金属等水质指标有显著影响。CCA的第一排序轴解释了景观指数与水质指标相关性的54.0%,前两排序轴累积能解释景观指数与水质指标相关性的87.6%,前两轴分别主要表达了城市化水平和景观破碎化水平的变化梯度。淡水河流域的景观格局特征从上游到下游呈现出城市—城乡交错—农村的景观梯度,水质变化也对应了这个梯度的变化,说明人类活动引起的流域土地覆盖及土地管理措施变化会对水质变化产生显著影响。     

Combining land cover mapping of coastal dunes with vegetation analysis

Question: Coastal dune systems are characterized by a natural mosaic that promotes species diversity. This heterogeneity often represents a severe problem for traditional mapping or ground survey techniques. The work presented here proposes to apply a very detailed CORINE land cover map as baseline information for plant community sampling and analysis in a coastal dune landscape. Location: Molise coast, Central Italy. Method: We analysed through an error matrix the coherence between land cover classes and vegetation types identified through a field survey. The CORINE land cover map (scale 1: 5000) of the Molise coast was used with the CORINE legend expanded to a fourth level of detail for natural and semi‐natural areas. Vegetation data were collected following a random stratified sampling design using the CORINE land cover classes as strata. An error matrix was used to compare, on a category‐by‐category basis, the relationship between vegetation types (obtained by cluster analyses of sampling plots) and land cover classes of the same area. Results: The coincidence between both classification approaches is quite good. Only one land cover class shows a very weak agreement with its corresponding vegetation type; this result was interpreted as being related to human disturbance. Conclusions: Since it is based on a standard land cover classification, the proposal has a potential for application to most European coastal systems. This method could represent a first step in the environmental planning of coastal systems.     

Modeling Effects of Forest Cover Reduction on Larval Walleye Survival in Lake Erie Tributary Spawning Basins

An integrated modeling approach is used to link land use to river discharge, and then to survival of larval walleye that hatch in northern Ohio streams draining into Lake Erie (USA). First, to link land use and river discharge, the parameters of a simple hydrologic model are statistically related to watershed landscape attributes, including forest cover. One such relationship allows estimation of the change in daily river discharge that could result from a reduction in basin-scale forest cover. Second, to represent the river discharge-larval survival link, we reexamine a dataset from Mion and others to propose a relationship between daily flow velocity, water temperature, and walleye larval survival. Together, these linked models provide estimates of the reduction in larval survival due to reduction in forest cover, along with the uncertainty of those estimates. For the Grand River watershed, decreasing forest cover from 45.2 to 30% is projected to reduce average larval survival by about 45%. In the adjacent Chagrin River, dropping cover from 62.5 to 30% reduces survival by almost 60%. The greater rate of reduction of survival in the Chagrin River as forest levels fall is explained by a relatively greater increase in storm flows for the Chagrin, due to more frequently saturated soils. Therefore, forest preservation in the Chagrin River watershed is projected to be more effective in preserving walleye larval tributary habitat.     

岷江上游小流域景观格局对土壤侵蚀过程的影响

以GIS为平台,利用泥沙输移分布模型模拟了岷江上游黑水流域和镇江关流域的流域侵蚀量、产沙量的空间分布,将模拟结果与土地利用图相结合,分析了各土地利用/覆被类型方式对侵蚀、产沙过程的影响,并利用景观空间负荷对比指数分析了土地利用/覆被类型随空间要素的配置、贡献权重和组成比例对土壤侵蚀的影响.结果表明:不同土地利用方式的土壤侵蚀模数不同,依次为裸岩>居民点>草地>农田>灌木林>林地;不同土地利用/覆被类型的产沙模数没有明显差异.2个流域土地利用/覆被类型随坡度的空间配置较优,随相对高度、相对距离和运移距离的空间配置较差;2个流域土地利用/覆被类型随着空间元素的配置各有优势,考虑土地利用/覆被类型的贡献权重后,镇江关流域的格局优势增加,当进一步考虑土地利用/覆被类型的组成比例时,镇江关流域的格局则优于黑水流域;只有综合考虑空间配置、贡献权重和组成比例,才能全面度量流域景观格局对土壤侵蚀的影响.坡度的景观空间负荷对比指数的构造不能准确地表现土地利用/覆被类型的贡献权重、组成比例对土壤侵蚀的影响,还需进一步改进.     

The Disconnect Between Restoration Goals and Practices: A Case Study of Watershed Restoration in the Russian River Basin, California

Over the past two decades, watershed restoration has dramatically increased internationally. California has been at the forefront, allocating billions of dollars to restoration activities through legislation and voter-approved bonds. Yet, the implications of restoration remain ambiguous because there has been little examination of restoration accomplishments and almost no analysis of the political context of restoration. This article addresses these gaps, utilizing a case study of the Russian River basin in Northern California. We identify trends that shed light on both the ecological and the political implications of restoration at a basin scale by examining a database of 787 restoration projects implemented in the Russian River basin since the early 1980s. Although a total of over $47 million has been spent on restoration in the basin, dominant forms of restoration are limited in scope to small-scale projects that focus on technical solutions to site-specific problems. The majority of restoration efforts are devoted to road repair, riparian stabilization, and in-stream structures, accounting for 62% of all projects. These types of projects do not address the broader social drivers of watershed change such as land and water uses. We suggest that restoration can become more effective by addressing the entire watershed as a combination of social and ecological forces that interact to produce watershed conditions.