Land Quality and Landscape Processes

This monograph contains a selection of scientific papers presented on the conference on Land Quality and Landscape Processes, hold in Keszthely, Hungary. It covers topics related to various aspects of land quality including : concepts of assessment; evaluation of biomass productivity ; bioindicators of land quality ; quality assessment of degraded land ; land use related data processingJRC.H.5-Land Resources Managemen

Modeling nitrogen loading in a small watershed in southwest China using a DNDC model with hydrological enhancements

The degradation of water quality has been observed worldwide, and inputs of nitrogen (N), along with other nutrients, play a key role in the process of contamination. The quantification of N loading from non-point sources at a watershed scale has long been a challenge. Process-based models have been developed to address this problem. Because N loading from non-point sources result from interactions between biogeochemical and hydrological processes, a model framework must include both types of processes if it is to be useful. This paper reports the results of a study in which we integrated two fundamental hydrologic features, the SCS (Soil Conservation Service) curve function and the MUSLE (Modified Universal Soil Loss), into a biogeochemical model, the DNDC. The SCS curve equation and the MUSLE are widely used in hydrological models for calculating surface runoff and soil erosion. Equipped with the new added hydrologic features, DNDC was substantially enhanced with the new capacity of simulating both vertical and horizontal movements of water and N at a watershed scale. A long-term experimental watershed in Southwest China was selected to test the new version of the DNDC. The target watershed\u27s 35.1 ha of territory encompass 19.3 ha of croplands, 11.0 ha of forest lands, 1.1 ha of grassplots, and 3.7 ha of residential areas. An input database containing topographic data, meteorological conditions, soil properties, vegetation information, and management applications was established and linked to the enhanced DNDC. Driven by the input database, the DNDC simulated the surface runoff flow, the subsurface leaching flow, the soil erosion, and the N loadings from the target watershed. The modeled water flow, sediment yield, and N loading from the entire watershed were compared with observations from the watershed and yielded encouraging results. The sources of N loading were identified by using the results of the model. In 2008, the modeled runoff-induced loss of total N from the watershed was 904 kg N yr−1, of which approximately 67 % came from the croplands. The enhanced DNDC model also estimated the watershed-scale N losses (1391 kg N yr−1) from the emissions of the N-containing gases (ammonia, nitrous oxide, nitric oxide, and dinitrogen). Ammonia volatilization (1299 kg N yr−1) dominated the gaseous N losses. The study indicated that process-based biogeochemical models such as the DNDC could contribute more effectively to watershed N loading studies if the hydrological components of the models were appropriately enhanced

Soil erosion and sediment yield in the upper Yangtze, China

Soil erosion and sedimentation are key environmental problems in the Upper Yangtze because of the ongoing Three Gorges Project (TGP), the largest hydro-power project in the world. There is growing concern about the rapid increase of soil erosion over the last few decades and its consequence for potential sedimentation in the reservoir. The study aims to examine controls on the spatial and temporal distributions of sediment transfer within the Upper Yangtze and the hydrological consequences of land use changes, using varied approaches at different catchment scales. First, soil erosion and sedimentation are examined using the radionuclide Cs-137 as a tracer within a small reservoir catchment in the Three Gorges Area. The results indicates that soil erosion on sloping arable land and the rates of reservoir sedimentation have been severe during the past 40 years, mainly due to cultivation on steep slopes. Changes in reservoir sedimentation rates are mainly attributed to land use changes. The suitability of the Cs-137 techniques for investigating soil erosion and sedimentation in intensely cultivated subtropical environments is also considered. The use of the technique for erosion investigation may have limitations due to the abundance of coarse soil textures, uncertainty about fallout deposition rates and the high incidence of human disturbance, but the technique shows promising perspectives for sedimentation investigation since a few dating horizons might be identified. Second, sediment and runoff measurement data for around 30 years from over 250 hydrological stations within the Upper Yangtze have been examined within a GIS framework. The dataset has been integrated with catchment characteristics derived from a variety of environmental datasets and manipulated with Arc/Info GIS. The analysis of the sediment load data has permitted identification of the most important locations of sediment sources, the shifting pattern of source areas in relation to land use change and sub-catchments exhibiting trending sediment yields corrected for hydrological variability. The study demonstrates the importance of scale dependency of sediment yield in both the identification of temporal change and the modelling of relationships between sediment yield and environmental variables, suggesting that the treatment of the scale problem is crucial for temporal-spatial studies of sediment yield

Advances in Hydraulics and Hydroinformatics Volume 2

This Special Issue reports on recent research trends in hydraulics, hydrodynamics, and hydroinformatics, and their novel applications in practical engineering. The Issue covers a wide range of topics, including open channel flows, sediment transport dynamics, two-phase flows, flow-induced vibration and water quality. The collected papers provide insight into new developments in physical, mathematical, and numerical modelling of important problems in hydraulics and hydroinformatics, and include demonstrations of the application of such models in water resources engineering

Landslide susceptibility assessment using the certainty factor and deep neural network

Areas with vulnerable ecological environments often breed many geological disasters, especially landslides, which pose a severe threat to the safety of people’s lives and property in these areas. To aid in landslide prevention and mitigation, an approach combining the coefficient of determination method (CF) and a deep neural network (DNN) were proposed in this study for landslide susceptibility evaluation. The deep neural network can excavate the deep features of samples and improve the accuracy of the susceptibility model. In addition, the logistic regression model (LRM) and support vector machine (SVM) were selected to create landslide susceptibility maps for comparison, which also involved the coefficient of determination method (CF). Based on landslide remote sensing interpretation and field investigations, a spatial database of mudstone landslides in the Xining area was established. Eight different conditional factors, including the elevation, slope, slope aspect, undulation, curvature, watershed, distance from a fault, and distance from a road, in the study area were selected as the evaluation factors to evaluate the susceptibility. The results revealed that four factors (i.e., the ground elevation, curvature, distance from a fault, and distance from a road) had relatively significant influences on the landslide susceptibility in the study area. Finally, the confusion matrix was used to evaluate the accuracy of the results obtained using the three methods, and the optimal result was selected to evaluate the landslide susceptibility in the study area. It was found that the combined CF-DNN method was more suitable for evaluating the landslide susceptibility in this area. Landslide susceptibility zoning was conducted to divide the study area into four sensitivity levels: low (32.65%), medium (35.12%), high (22.44%), and extremely high (9.79%) susceptibility. The high-risk areas were primarily distributed in the high-elevation areas along the eastern edge of the Huangshui Basin

Lower Atmosphere Meteorology

The Atmosphere Special Issue “Lower Atmosphere Meteorology” deals with the meteorological processes that occur in the layer of the atmosphere close to the surface. The interaction between the biosphere and the atmosphere is made through the lower layer and can greatly influence living beings and materials. The analysis of the meteorological parameters provides a better understanding of processes within the lower atmosphere and involved in air pollution, climate, and weather. The mixed layer height, the wind speed, and the air parcel trajectory have a relevant interest due to their marked impact on population and energy production. The research also comprises aerosols, clouds, and precipitation, analysing their spatiotemporal variations. This issue addresses features of gases in the atmosphere and anthropogenic greenhouse emission estimates, which are also conditioned by the lower atmosphere meteorology

Agricultural Trajectories in Yunnan, Southwest China: a comparative analysis of archaeobotanical remains from the Neolithic to the Bronze Age

This dissertation investigates the emergence and development of agricultural practices in the southwest Chinese province of Yunnan, between the 3rd and 1st millennia BC. Drawing from previously unstudied archaeobotanical remains from the sites of Baiyangcun, Haimenkou, and Dayingzhuang; this research analyses compositional and chronological changes in the crop assemblage from each site. These sites are located in the strategic region of sanjiang, at the crossroads of three main Asian rivers: Yangzi, Mekong, and Salween. Local and regional developments of agricultural systems are explored through the comparison of these new material with other published datasets from Yunnan, the surrounding provinces of Sichuan, Tibet, Chongqing, Guangxi, and mainland Southeast Asian countries. The main research questions addressed in this dissertation are: -What was the basis of early agriculture in Yunnan? -Given that the first attested agricultural systems in Southwest China appear 3000 to 2000-years later than those associated with domestication centres in North China and along the Yangzi River, to what extent can agricultural practices in Yunnan be derived entirely from migrating farmers, or did adoption (acculturation) by local forager populations play a role? -What role did native wild plants play in Yunnan Neolithic and Post-Neolithic subsistence, and were there any local processes of domestication underway? -With regards to rice, what was the ecology of rice cultivation? Did this differ either from source regions along the Yangzi, or from the early systems in Southeast Asia, which have sometimes been suggested to have origins in Yunnan? The results contained in this thesis provide archaeological evidence that was until now lacking to evaluate the validity of the language/farming dispersal hypothesis in the context of the Austroasiatic languages dispersal, as well as laying an important archaeological and chronological framework for studying of the emergence of a settled agricultural lifestyle in Yunnan

Integrated Ecosystem Assessment of Western China

Western Development is an important strategy of China Government. The ecological environment in the western region of China is very fragile, and any improper human activity or resource utilization will lead to irrecoverable ecological degradation. Therefore, the integrated ecosystem assessment in the western region of China is of great significance to the Western Development Strategy. This project, Integrated Ecosystem Assessment of Western China (MAWEC), will provide very important scientific foundations for both the central and local governments to make decisions on ecological construction, thus assuring the successful implementation of the Western Development Strategy. Meanwhile, MAWEC as one of the MA sub-global assessments is contributing to strengthen capability in boosting the development of the ecological science, interaction between different subjects, and combination between scientific research and practice, and pushing forward international cooperation in the relevant fields

Structure of endemic fish assemblages in the upper Yangtze River basin and population differentiation of an endangered endemic fish (Gobiocypris rarus)

Le fleuve Yangtze (Changjiang en chinois) supporte une très riche biodiversité de poissons, avec environ 400 espèces au total. Assimilée à une barrière eco-fonctionnelle, la partie amont du Yangtze présente des conditions environnementales naturelles exceptionnelles, avec une hétérogeneité bien prononcée des habitats, un système de drainage bien développé, une abondance en ressources en eau and une biodiversité importante. Ainsi, on dénombre 286 espèces de poissons dans la partie amont du Yangtze, dont 124 endémiques à cette région. Cependant, cette biodiversité est fortement menacée, notamment du fait de la surexploitation, de la pollution des eaux, des barrages hydroélectriques, des invasions biologiques et des modifications environnementales. Il est de ce fait impératif de mesurer les influences de ces changements environnementaux sur la ressource piscicole, de telle sorte à accélérer la mise en place de mesures de conservation. En conséquent, cette thèse avait pour objectif d'apporter des éléments visant à favoriser la conservation des espèces endémiques de poisons dans la partie amont du fleuve Yangtze. Dans la première partie de la thèse, l'objectif est d'illustrer les mécanismes de structuration des assemblages de poissons pour améliorer les connaissances des processus écologiques de la partie amont du fleuve Yangtze, i.e. déterminer les patrons spatiaux de distribution des poissons endémiques et les relations avec les variables environnementales (publications P1 & P2). Nous avons pu définir cinq assemblages de poissons endémiques dans le haut Yangtze caractérisés par des différences significatives au niveau de la richesse spécifique. Ces assemblages reflètent le gradient longitudinal de la distribution des espèces et de richesse avec une forte corrélation avec la topographie et la géomorphologie du fleuve Yangtze. Chaque assemblage est caractérisé par des espèces endémiques " indicatrices ". Le patron de distribution des poissons endémiques est significativement corrélé avec les facteurs environnementaux de l'utilisation du sol du bassin versant et des caractéristiques du fleuve. Des modèles mixtes utilisant simultanément des paramètres d'utilisation du sol et des caractéristiques du fleuve permettent d'assurer une meilleure prédiction de l'assemblage des poissons endémiques du Yangtze, comparés à des modèles utilisant séparément les 2 groupes de paramètres environnementaux. Enfin, nous suggérons trois points importants pour la conservation des espèces endémiques de poissons du haut Yangtze: sélection de plusieurs sites protégés de diverses espèces; maintient d'une partie courante naturelle pour chaque cours d'eau parmi les affluents; développement de mise en réserve des affluents. Dans la deuxième partie de la thèse, afin d'obtenir une bonne connaissance d'une espèce de poisson endémique en danger (Gobiocypris rarus) et fournir des instructions pour la conservation des autres espèces du haut Yangtze, nous avons utilisé cette espèce comme exemple d'étude de conservation à l'aide de marqueurs microsatellites et morphologiques (publications P3, P4 et P5). L'habitat typique de G. rarus était caractérisé par une seule population stable qui présentait une taille effective relativement large et aucune évidence de structure cryptique au cours des dix dernières années. Les forces maintenant cette diversité génetique était principalement les fluctuations environnementales et les traits d'histoire de vie propres à G. rarus. A une échelle spatiale plus étendue, nous avons trouvé des patrons significatifs de différentiation entre plusieurs populations de G. rarus, d'un point de vue génétique mais aussi morphologique. Particulièrement, deux clusters génétiques reflétant la structure du réseau hydrographique ont été identifiés. L'étude comparée des patrons d'isolation par la distance nous a permis de conclure que G. rarus était capable de migrer de réseau en réseau davantage via les canaux d'irrigations que via l'embouchure des rivières. Nous avons également mis en évidence un dimorphisme sexuel cryptique (i.e. visible uniquement que quelque trait morphologique continu). Finalement, au vue de cette distribution discontinu (tant d'un point de vue génétique que morphologique) et étant donné les menaces écologiques attendu, nous conseillons que la plupart des populations étudiées soit préservées. Plus particulièrement, les populations T1, T2, Q2, M3 et D2 devraient être prioritaire d'un point de vue de la conservation, avec une gestion de l'habitat et de l'espèce particulièrement forte dans ces localités.The Yangtze River, also called Changjiang, supports rich biodiversity, especially diverse fish fauna, i.e., about 400 fish species and subspecies. As an eco-functional barrier of the Yangtze River, the upper Yangtze River exhibits complicated natural environment, pronounced habitat heterogeneity, well-developed drainage system, abundant water resources and rich biodiversity. There were 286 fish species and subspecies distributing in the upper Yangtze River, among which 124 species were endemic. However, these fish resources are experiencing large threats: overexploitation, water pollution, hydropower projects, invasion by exotic species, and global environmental changes. It is imperative to evaluate the influences of the changes in environmental features on the fish resources and to accelerate the progress of conservation projects. Therefore, two parts of content have been studied in this thesis for the conservation of endemic fishes in the upper Yangtze River. Firstly, for the purpose of providing insight into mechanisms structuring fish assemblages and enhancing knowledge on ecological processes in the upper Yangtze River, spatial pattern of endemic fishes in the upper Yangtze River basin and their relationship with environmental features have been studied in P1 and P2 of this thesis. We identified five endemic fish assemblages in the upper Yangtze River basin. Not only species composition but also endemic species richness varied significantly among these five assemblages. They not only reflect the longitudinal gradient pattern but also are closely correlated with the topography and geomorphology of the Yangtze River. Each endemic fish assemblage has its specific indicator species. The endemic fish distribution patterns are significantly correlated with environmental factors such as land-cover features and river characteristics. The mixed models containing both land-cover features and river characteristics are more effective than any individual one in explaining complex endemic fish distribution patterns in the upper Yangtze River basin. Finally, we suggested that three key points for the conservation of endemic fishes in the upper Yangtze River basin should be paid more attention: selection of several protected sites aiming at various species; maintenance of at least one flowing reach in each river; developing the conservation of tributaries. Secondly, in order to obtain enough background of an endangered endemic fish (Gobiocypris rarus) and provide guidelines for other species conservation in the upper Yangtze River basin, the author used this Chinese rare minnow (G. rarus) as an example to do the studies of conservation biology using microsatellite markers and morphological traits in P3, P4 and P5 of this thesis. The type locality of G. rarus held a single stable and healthy population with a relatively large Ne and no cryptic structure during nearly ten years. The forces maintaining their genetic diversity were mainly from environmental fluctuations and life history traits. In addition, there were significant differentiations among wild populations of G. rarus not only in genetic markers but also in morphometric traits. Two obvious genetic clusters were revealed among wild populations of G. rarus, reflecting out water system structure to some extent. An isolation-by-riparian-distance pattern was identified, indicating that G. rarus might migrate through some man-made channels of hydropower projects but not through the mouth of the Minjiang and Tuojiang Rivers to exchange genes. Sexual dimorphism existed in morphometric traits of G. rarus wild populations. Finally, in the view of discontinuous distribution, significant genetic and quantitative differentiation of wild populations, and large threats from human activities, all the studied populations should be protected. Especially, populations T1, T2, Q2, M3 and D2 should be in prior conservation, and a habitat and species management area should be established in its type locality (viz. population D2)