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Aim Habitat types are involved in shaping biological traits of their resident native species and thus they determine, to a large extent, in which habitats particular species will succeed if invading outside their native range. However, the correspondences between habitats that invasive aliens occupy in the native and invaded ranges are poorly known. We explore the relationships between (1) habitats of invasive species in their native and invaded ranges and (2) native-range habitats and the direction of invasion (from/to Europe; from/to the Old World). Location Global. Methods Descriptions of native- and invaded-range habitats of 286 invasive species were extracted from the literature and transformed into 12 habitat types. The differences between native-range habitats according to the direction of invasion and between habitats occupied in the native and invaded ranges were tested by log-linear models and deletion tests. Results Most frequent invaders were species confined to forests (98 species), riparian habitats (80), grasslands (80) and man-made habitats (73) in their native ranges. Native-range habitats differed between species invading from and to Europe (110 and 41, respectively) as well as between species invading from and to the Old World (213 and 75, respectively). Grasslands were the most overrepresented native-range habitat for species invading from Europe compared to species invading Europe; wetlands were the most overrepresented native-range habitats for species invading the Old World compared to species invading from the Old World. Many species that originated from forests invade grasslands, and, conversely, many grassland species invade open forests. Main conclusions European grassland species are much more successful as world-wide invaders than grassland species from other continents invading Europe, and New World wetland species invading the Old World are more successful than wetland species invading from the Old World. Successful invaders are adapted to a broad spectrum of successional phases ranging from grasslands to forests.

Flooding is an important global hazard that causes an average annual loss of over 40 billion USD and affects a population of over 250 million globally. The complex process of flooding depends on spatial and temporal factors such as weather patterns, topography, and geomorphology. In urban environments where the landscape is ever-changing, spatial factors such as ground cover, green spaces, and drainage systems have a significant impact. Understanding source areas that have a major impact on flooding is, therefore, crucial for strategic flood risk management (FRM). Although flood source area (FSA) identification is not a new concept, its application is only recently being applied in flood modelling research. Continuous improvements in the technology and methodology related to flood models have enabled this research to move beyond traditional methods, such that, in recent years, modelling projects have looked beyond affected areas and recognised the need to address flooding at its source, to study its influence on overall flood risk. These modelling approaches are emerging in the field of FRM and propose innovative methodologies for flood risk mitigation and design implementation; however, they are relatively under-examined. In this paper, we present a review of the modelling approaches currently used to identify FSAs, i.e. unit flood response (UFR) and adaptation-driven approaches (ADA). We highlight their potential for use in adaptive decision making and outline the key challenges for the adoption of such approaches in FRM practises.

Comparing species that become invasive with others from the same regional species pool that do not invade raises several issues about the accuracy of analyses attempting to define the determinants of invasiveness. The delimitation of the source area and deciding which species group(s) to include are especially relevant in analyses focusing on species originating in Europe. Historical patterns of immigration of alien species into Europe must be considered since European floras comprise a complex mix of native species, historical introductions (archaeophytes) and relative newcomers (neophytes). We make three main points: (1) Archaeophytes (species introduced to Europe before the discovery of America) differ from natives in a number of traits and in historical association with people; it is misleading to lump archaeophytes with native taxa. (2) Taxa from climatically and geographically different regions, representing distinct floristic geoelements, need to be treated separately, and not as a homogenous pool of potential invaders. Restricting the source species pool to native taxa with comparable phytogeographical characteristics reduces the variation associated with chance of dispersal by humans from the source area. (3) For prediction, a clear distinction should be made between accuracy (the proportion of those found to be alien that were also predicted to be there) and reliability (or predictive value, the proportion of those predicted to become aliens that do so). Information accumulated over centuries by botanists in Central Europe provides an excellent opportunity to deal with these issues and avoid spurious results. To illustrate these issues, we revisit a recently published study of Central-European plant species as invaders in two Argentinean provinces (Prinzing et al., 2002) to explore and demonstrate the implications of the above points. We hope that future studies will build on these points to achieve more reliable predictions.

A science-based geographic information system (GIS) approach is presented to target critical source areas in watersheds for conservation buffer placement. Critical source areas are the intersection of hydrologically sensitive areas and pollutant source areas in watersheds. Hydrologically sensitive areas are areas that actively generate runoff in the watershed and are derived using a modified topographic index approach based on variable source area hydrology. Pollutant source areas are the areas in watersheds that are actively and intensively used for such activities as agricultural production. The method is applied to the Neshanic River watershed in Hunterdon County, New Jersey. The capacity of the topographic index in predicting the spatial pattern of runoff generation and the runoff contribution to stream flow in the watershed is evaluated. A simple cost-effectiveness assessment is conducted to compare the conservation buffer placement scenario based on this GIS method to conventional riparian buffer scenarios for placing conservation buffers in agricultural lands in the watershed. The results show that the topographic index reasonably predicts the runoff generation in the watershed. The GIS-based conservation buffer scenario appears to be more cost-effective than the conventional riparian buffer scenarios.

The impact of climate warming on the water cycle and water resources is an important issue in science and for sustainable socioeconomic development. The drainage area above Tangnaihai station is the source area of the Yellow River, which is located in the Qinghai–Tibet Plateau and yields 41.3 % of the river’s total natural runoff. Thus, it is known as the “water tower of the Yellow River.” Based on climate and hydrometric data from 1956 to 2008, the purpose of this study is to deal with the influence of climate warming on the water cycle in this region and thereby to provide some knowledge for sustainable water resources management of the Yellow River. The statistical analysis shows basically no trend in annual precipitation, but a significant rising trend in air temperature. Hence, this area is ideal to study the response of the water cycle system to climate warming. We found nonlinear variations in annual runoff ( Q w ) and the runoff–precipitation ratio ( R rp ): they increased to a peak and then decreased. According to the response of R rp to rising temperature, we established a three-stage descriptive model for the complex response of runoff generation to the rising air temperature. The mechanism of the complex response is explained based on the evidence of environmental changes previously reported in the study area, driven by rising temperatures.

With China’s rapid economic growth and increasing speed of urbanization, water pollution accidents have become one kind of environmental pollution source in China and bring potential risk to urban drinking water safety. The Huangjuedu Drinking Water Source Area is an important water source in Chongqing City (Southwest China) and a water intake source for the Jiangnan Waterworks of the Chongqing Drinking Water Company. There are still risks of water pollution accidents caused by ship leakage, road traffic accidents, chemical plant leakage, etc. The safety of the drinking water area is related to regional residents’ health and life safety and also has a profound impact on economy development and social stability. To reduce the harmful impacts of water pollution, it is of great scientific value and practical significance to analyze the pollutant diffusion of water pollution accidents with the Three Gorges Reservoir Area drinking water source security platform. In this paper, a two-dimensional water quality monitoring model was applied, and the digital elevation model was incorporated into the geographic information system, which generated a computational grid. Then, the Three Gorges Reservoir Area drinking water source security platform was developed. The platform can predict the water flow velocity, pollutant concentration at the drinking water inlet, and the spatial and temporal distribution of pollutants in the whole water source area. Furthermore, a hypothetical ammonia nitrogen leak accident was analyzed using this safety platform. The ammonia nitrogen concentration at the intake of the drinking water source area was detected and analyzed by the security platform from the time of the accident until the concentration dropped to the background during four water periods under different wind direction conditions. The pollutants took 19, 22, 25, and 40 min to reach the water quality standard during the four water periods. Moreover, the diffusion of ammonia nitrogen in the southeast wind was faster than that in the southwest wind. The results showed that the platform is scientific and practical, and the prediction results are helpful for the Emergency Management Department to quickly and accurately predict the migration of ammonia nitrogen pollution and make corresponding plans under accident conditions.

Non-point source (NPS) pollution is an important problem that has been threatening freshwater resources throughout the world. Best Management Practices (BMPs) can reduce NPS pollution delivery to receiving waters. For economic reasons, BMPs should be placed at critical source areas (CSAs), which are the areas contributing most of the NPS pollution. The CSAs are the areas in a watershed where source coincides with transport factors, such as runoff, erosion, subsurface flow, and channel processes. Methods ranging from simple index-based to detailed hydrologic and water quality (HWQ) models are being used to identify CSAs. However, application of these methods for Canadian watersheds remains challenging due to the diversified hydrological conditions, which are not fully incorporated into most existing methods. The aim of this work is to review potential methods and challenges in identifying CSAs under Canadian conditions. As such, this study: (a) reviews different methods for identifying CSAs; (b) discusses challenges and the current state of CSA identification; and (c) highlights future research directions to address limitations of currently available methods. It appears that applications of both simple index-based methods and detailed HWQ models to determine CSAs are limited in Canadian conditions. As no single method/model is perfect, it is recommended to develop a ‘Toolbox’ that can host a variety of methods to identify CSAs so as to allow flexibility to the end users on the choice of the methods.

Water eutrophication caused by the extensive expansion of slope farming has caused the high attention of the Chinese government. We choose Lake Tianmu basin as the study area because it can represent vast majority of basins plagued by water eutrophication derived from slope tillage in southern China. The water ecosystem in the reservoir Daxi and Shahe within the basin has been seriously threatened by multiple pollution sources related to many intricate human activities especially agricultural production. For the first time, we identified the critical source areas (CSAs) within the basin based on nutrient load and nutrient load intensity (NLI), and on this basis, we further excavated the main causes of pollution and proposed pertinent remediation measures. The results based on the calibrated Soil and Water Assessment Tool model indicated that the TN load of each reservoir remarkably exceeded their respective water environmental capacity from 2014 to 2018. Accordingly, six main tributaries with great nutrient contributions and their corresponding sub-basins were then identified. Overall, tea and rice plantations appear to be the major nutrient contributors to reservoir Daxi. And the main nutrient sources for reservoir Shahe are tea plantations, orchards, farmland, forestland, and point sources. Regarding the CSAs identified only by nutrient load, agronomic measures such as reducing fertilizer amount, biochar application, straw incorporation, and plastic mulch coverage can be employed to improve soil water retention and curb soil erosion. Regarding the CSAs identified by nutrient load intensity (NLI), the CSAs with narrow areas should be turned directly into forestland. For the CSAs with large areas, engineering measures such as constructing ecological riparian zone, filtration, and sedimentation tank can be employed to prevent pollutants from entering downstream reaches. Overall, the present results can provide the decision-making support for the safe and efficient management of watershed land use in southern China. Graphical abstract

Nine methods to determine local-scale aerodynamic roughness length ( z 0 ) and zero-plane displacement ( z d ) are compared at three sites (within 60 m of each other) in London, UK. Methods include three anemometric (single-level high frequency observations), six morphometric (surface geometry) and one reference-based approach (look-up tables). A footprint model is used with the morphometric methods in an iterative procedure. The results are insensitive to the initial z d and z 0 estimates. Across the three sites, z d varies between 5 and 45 m depending upon the method used. Morphometric methods that incorporate roughness-element height variability agree better with anemometric methods, indicating z d is consistently greater than the local mean building height. Depending upon method and wind direction, z 0 varies between 0.1 and 5 m with morphometric z 0 consistently being 2–3 m larger than the anemometric z 0 . No morphometric method consistently resembles the anemometric methods. Wind-speed profiles observed with Doppler lidar provide additional data with which to assess the methods. Locally determined roughness parameters are used to extrapolate wind-speed profiles to a height roughly 200 m above the canopy. Wind-speed profiles extrapolated based on morphometric methods that account for roughness-element height variability are most similar to observations. The extent of the modelled source area for measurements varies by up to a factor of three, depending upon the morphometric method used to determine z d and z 0 .

Migratory insects are a key component of terrestrial ecosystems, but understanding their full contribution is challenging as they are difficult to track, and migration often takes place at high altitude. Migration hotspots offer an exceptional opportunity to study these otherwise indiscernible movements as migration can be visible at ground level; however these events are often also ephemeral and reported only from chance encounters. It is therefore often difficult to fully characterise the range and number of species involved, the drivers of migration or to appreciate the potential interactions and ecological roles of the migrants. Here we pursue field evidence suggesting that the Karpaz peninsula in northeast Cyprus is a suitable location to systematically collect data on migratory insects. In the spring of 2019, using a combination of timed‐counts, migration‐camera traps and netting we documented over 39 million day‐flying insects from eight orders arriving on Cyprus at rates of up to 5900 insects m‐1 min‐1. Mass arrivals were correlated with higher temperatures and easterly winds. Wind direction and normalised vegetation difference index (NDVI) data suggest that these insects had their natal origins in locations including Syria, Iraq and Saudi Arabia. It is estimated that many billions of insects left the coast of the Middle East heading west into Europe during the study period. While the migrant assemblage was diverse, Diptera were by far the most numerous insect order (86%) followed by Lepidoptera (10%). These migrating insects play a range of vital ecological roles including cross‐continental pollination and the transfer of important nutrients. We believe that the very infrequently explored processes described in this manuscript have important consequences for ecosystems in the destinations of these migratory insects across Europe.