Modelling the Linkage Between Landscape Metrics and Water Quality Indices of Hydrological Units in Sihu Basin, Hubei Province, China: An Allometric Model

AbstractStudying quantitative relationships between landscape pattern and water quality is a fundamental step to assess the impacts of non-point source pollution. Many hydrological models with multi-functionality have been developed as useful tools to study several key mechanisms in non-point source pollution. In landscape ecological studies, however, the empirical modelling approaches have been dominated with emphasis on the relationships between the landscape metrics and water quality indices. The main techniques for developing those models of landscape-water quality are statistical regression analysis based on linear models. In this article, Allometric models and the traditional multiple linear regression models for estimating the linkage between landscape metrics and water quality were tested in Sihu Basin, Hubei Province, China. The models at patch class level were established in 24 hydrological units of the basin, which took nine water quality indices (EC, pH, SS, DO, COD, TN, TP, NO3--N, NH4+-N) as the dependent variables and eighteen landscape metrics calculated in FRAGSTATS 3.3 as independent variables. The results suggested that, compared with the traditional multiple linear regression models, Allometric models were more suitable for SS, DO, TP, TN, NH4+-N, in which landscape pattern metrics could explain the 80.5%, 77.7%, 58.2%, 43.9%, 67.6% of total variation, respectively. There had little difference between multiple linear regression models and Allometric models for EC and NO3--N. The coefficients of determination in Allometric models were not as strong as that obtained in the multiple linear regression models for pH and COD. The above results indicated that using Allometric model may potentially provide a new way to study the linkage between landscape metrics and water quality indices, which will help protect our regional water resources

Climate change impacts on central China and adaptation measures

Abstract In Central China, the obvious climate change has happened along with global warming. Based on the observational analysis, the climate change has significant effects, both positive and negative, in every field within the study area, and with the harmful effects far more prevalent. Under the scenario A1B, it is reported that temperature, precipitation, days of heat waves and extreme precipitation intensity will increase at respective rates of 0.38 • C per decade, 12.6 mm per decade, 6.4 d and 47 mm per decade in the 21st century. It is widely believed that these climate changes in the future will result in some apparent impacts on agro-ecosystems, water resources, wetland ecosystem, forest ecosystem, human health, energy sectors and other sensitive fields in Central China. Due to the limited scientific knowledge and researches, there are still some shortages in the climate change assessment methodologies and many uncertainties in the climate prediction results. Therefore, it is urgent and essential to increase the studies of the regional climate change adaptation, extend the research fields, and enhance the studies in the extreme weather and climate events to reduce the uncertainties of the climate change assessments

Direct and indirect loss of natural habitat due to built-up area expansion:A model-based analysis for the city of Wuhan, China

Urbanization has been responsible for the loss of cropland worldwide, especially in China. To guarantee national food security, China has implemented a series of policies to protect cropland. One of these policies requires that one-hectare cropland should be reclaimed when urban expansion occupies one-hectare cropland. Since most cropland reclamation leads to a conversion of natural habitat, such as wetland and grassland, urban expansion may lead to (indirect) natural habitat loss in addition to direct loss from conversion of into urban area. While several studies assessed the direct habitat loss resulted from built-up area expansion, few studies investigated the indirect losses caused by cropland displacement. In this paper, a model-based approach is applied to explore both direct and indirect impacts of built-up area expansion on natural habitat loss for the city of Wuhan, China, between 2010 and 2020 using different scenarios. Our scenarios differ in the implementation of strict cropland protection policies and ecosystem conservation strategies. Results show that the indirect loss of natural habitat due to cropland displacement under strict cropland protection policies far outweighs the direct loss due to built-up area expansion alone. Moreover, we found that ecosystem conservation strategies mainly influence the type of natural habitat that is affected, while the total amount of natural habitat loss remains relatively constant

Combining remote sensing and ground census data to develop new maps of the distribution of rice agriculture in China

Large-scale assessments of the potential for food production and its impact on biogeochemical cycling require the best possible information on the distribution of cropland. This information can come from ground-based agricultural census data sets and/or spaceborne remote sensing products, both with strengths and weaknesses. Official cropland statistics for China contain much information on the distribution of crop types, but are known to significantly underestimate total cropland areas and are generally at coarse spatial resolution. Remote sensing products can provide moderate to fine spatial resolution estimates of cropland location and extent, but supply little information on crop type or management. We combined county-scale agricultural census statistics on total cropland area and sown area of 17 major crops in 1990 with a fine-resolution land-cover map derived from 1995–1996 optical remote sensing (Landsat) data to generate 0.5° resolution maps of the distribution of rice agriculture in mainland China. Agricultural census data were used to determine the fraction of crop area in each 0.5° grid cell that was in single rice and each of 10 different multicrop paddy rice rotations (e.g., winter wheat/rice), while the remote sensing land-cover product was used to determine the spatial distribution and extent of total cropland in China. We estimate that there were 0.30 million km2 of paddy rice cropland; 75% of this paddy land was multicropped, and 56% had two rice plantings per year. Total sown area for paddy rice was 0.47 million km2. Paddy rice agriculture occurred on 23% of all cultivated land in China

Trade-Offs between Economic Benefits and Ecosystem Services Value under Three Cropland Protection Scenarios for Wuhan City in China

Over the past few decades urbanization and population growth have been the main trend all over the world, which brings the increase of economic benefits (EB) and the decrease of cropland. Cropland protection policies play an important role in the urbanization progress. In this study, we assess the trade-offs between EB and ecosystem services value (ESV) under three cropland protection policy scenarios using the LAND System Cellular Automata for Potential Effects (LANDSCAPE) model. The empirical results reveal that trade-offs between EB and ESV in urbanizing areas are dynamic, and that they considerably vary under different cropland protection policy scenarios. Especially, the results identify certain "turning points" for each policy scenario at which a small to moderate growth in EB would result in greater ESV losses. Among the three scenarios, we found that the cropland protection policy has the most adverse effect on trade-offs between EB and ESV and the results in the business as usual scenario have the least effect on the trade-offs. Furthermore, the results show that a strict balance between requisition and compensation of cropland is an inappropriate policy option in areas where built-up areas are increasing rapidly from the perspective of mitigating conflict between EB and ESV and the numbers of cropland protection that restrained by land use planning policy of Wuhan is a better choice

Integrated Infrastructures for an Urban Lake in Wuhan, China

One of the consequences of China’s rapid urbanization is the disappearance, or at least, mismanagement of the many lakes of the Central Yangtze River Basin. The thesis investigates the situation by conducting a complex system analysis, revealing four most pressing issues surrounding the lakes: flood management, sustaining agricultural practice, controlling urban development and maintaining a healthy ecosystem. The inadequacy in Central Yangtze River Basin’s flood capacity requires that the many lakes in the region be preserved and connected to form a flood retention network. Unfortunately, this preservation is threatened by urban development that seeks to infill the lakes. As well, many of the lakes are now divided into independent lotus farms and fish ponds which do not provide for a sustainable aquatic ecosystem. The city of Wuhan and its Lake Shahu is the focus of this thesis. Lake Shahu is a microcosm of the regional condition, and its centrality within the city of Wuhan brings about a particular set of problems, namely, the lake is perceived as an obstacle for communication and transit as well as an impediment for much needed city expansion. The thesis proposes a solution to the complex problem surrounding Lake Shahu by synthesizing a system of integrated infrastructure which would reconnect the lake and the Yangtze River, as well as provide a flood berm, public spaces, lotus farms, fisheries, wetlands and an artificial platform as land for city expansion. The infrastructural system is to instigate a process of transformation which sets up a symbiotic relationship among elements on site. For example, the Land Over Water project will allow penetration of sunlight to sustain the ecosystem below while staging a lively urban life above and supplying the lotus farms below with grey water collected from households. The design approach, known as Landscape Urbanism, is exemplified by Field Operation’s Fresh Kills Landfill Rehabilitation project where agricultural techniques and strategic planting are used to create a diverse range of habitats and event spaces over the course of 30 years. In the case of Lake Shahu, the importance of agriculture is highlighted for its engineering potential as well as its economic capacity to support the remaining rural farming population in the area. Aided by the transformation of the landscape and given the tools for monitoring the lake’s ecosystem, the farmers and fishermen can eventually become stewards of the land and water. Not unlike Fresh Kills, the project of Lake Shahu is staged for a 35-year period. The project evolves along the rapid development of China at a much slower pace as the natural processes required to stabilize the landscape will take a long time. By the end of the transformation, a sustainable system capable of adapting to changes in the urban, agrarian and natural environment will be able to support generations to come

Isolation and characterization of 13 new microsatellite markers in the triangle mussel (Hyriopsis cumingii)

Microsatellite enriched library of Hyriopsis cumingii was constructed according to the strong affinity between biotin and streptavidin. One hundred clones with foreign inserts were sequenced and 65 clones were screened for usable microsatellites, of which 36 were deemed unique, of sufficient length (more than 8 repeats) and possessed adequate flanking regions for primer designment. Among 36 primer pairs designed, 25 yielded scorable amplification products. Upon testing 30 individuals were sampled using the 25 pair primers from Dongting Lake of Hunan Province, China. Then thirteen polymorphic microsatellite markers were isolated and characterized. These loci exhibited high levels of genetic polymorphism, so the observed number of alleles per locus ranged from 4 to 9. The ranges of observed and expected heterozygosity were 0.2543 to 0.8913 and 0.3629 to 0.8217, respectively, and the average polymorphic information content was 0.5198. Two microsatellite loci were significantly deviated from Hardy-Weinberg equilibrium due to the presence of null alleles, and no linkage disequilibrium found. These microsatellite loci will be useful for assessing the genetic diversity and population structure of H. cumingii

Spatio-Temporal Change of LakeWater Extent in Wuhan Urban Agglomeration Based on Landsat Images from 1987 to 2015

Urban lakes play an important role in urban development and environmental protection for the Wuhan urban agglomeration. Under the impacts of urbanization and climate change, understanding urban lake-water extent dynamics is significant. However, few studies on the lake-water extent changes for the Wuhan urban agglomeration exist. This research employed 1375 seasonally continuous Landsat TM/ETM+/OLI data scenes to evaluate the lake-water extent changes from 1987 to 2015. The random forest model was used to extract water bodies based on eleven feature variables, including six remote-sensing spectral bands and five spectral indices. An accuracy assessment yielded a mean classification accuracy of 93.11%, with a standard deviation of 2.26%. The calculated results revealed the following: (1) The average maximum lake-water area of the Wuhan urban agglomeration was 2262.17 km2 from 1987 to 2002, and it decreased to 2020.78 km2 from 2005 to 2015, with a loss of 241.39 km2 (10.67%). (2) The lake-water areas of loss of Wuhan, Huanggang, Xianning, and Xiaogan cities, were 114.83 km2, 44.40 km2, 45.39 km2, and 31.18 km2, respectively, with percentages of loss of 14.30%, 11.83%, 13.16%, and 23.05%, respectively. (3) The lake-water areas in the Wuhan urban agglomeration were 226.29 km2, 322.71 km2, 460.35 km2, 400.79 km2, 535.51 km2, and 635.42 km2 under water inundation frequencies of 5%–10%, 10%–20%, 20%–40%, 40%–60%, 60%–80%, and 80%–100%, respectively. The Wuhan urban agglomeration was approved as the pilot area for national comprehensive reform, for promoting resource-saving and environmentally friendly developments. This study could be used as guidance for lake protection and water resource management