Poyang Lake is continuously shrinking and losing its function on account of deforestation and reclamation, causing water quality deterioration, frequent floods and ecological damages that impede economic growth. The research mainly analyzes the cause of Poyang Lake reclamation, its development, and pros and cons through historical literatures. The fact is found from 13th -19th centuries that farmers individually reclaimed the lake had caused external uneconomic problems. It not only negatively impacted local ecology but resulted in economic burden to the local government, who originally considered that the reclamation could bring in tax increases; however, the local financial resources are not sufficient to resolve existing problems. Under the contradictions among economic development, ecological protection, individual benefits and the overall security, the problems will continuously exist. The results of this research give an overall introduction concerning Poyang Lake in China. By illustrating the causes and impacts of reclamation and governances for lake, a relation among a specific political system, economic growth, ecological changes and policies can be demonstrated and underlying factors of flood disaster in China can be summarized.

Field measurements were combined with synthetic aperture radar (SAR) images to evaluate the use of C-band multi-polarized radar remote sensing for estimating plant parameters (plant height, fresh biomass, dry biomass and vegetation water content) of wetland vegetation, and mapping the dynamics of water bodies, wetlands (natural wetlands and rice paddies) and flooding extents in the Poyang Lake region. The capacity of L-band SAR in land cover mapping was also investigated by integrating with optical imagery. / Hydrological patterns in Poyang Lake are the dominant factor controlling the spatial and temporal variations of wetland species in Poyang Lake. Water levels in this region are primarily governed by five rivers (Ganjiang river, Xiushui river, Raohe river, Fuhe river, and Xinjiang river). Its northern region is also influenced by the backflow from Yangtze River. The above-ground total biomass increased steadily from March following the hydrological cycle. Wetland species colonizing at different altitudes were gradually flooded from late spring to summer. Carex spp. died during flooding periods and started another growth cycle in autumn after flooding receded. Canopy volume dominates the radar backscattering mechanism in Carex spp. wetlands during their growth period, but the temporal variation of radar backscatter from these wetlands is mainly influenced by flooding. Tall wetland species (Miscanthus sacchariflorus, Phragmites communis Trin., and others) still emerged above water surfaces during flooding peaks and started to senesce in autumn. Surface backscattering mechanism is dominant during the early growing stage and the senescent period of tall vegetation. Plant canopy variation controlled the temporal dynamics of radar backscatters from Phragmites communis Min. Radar backscattering mechanisms from Miscanthus sacchariflorus wetlands were more complicated during the flooding periods. The variations of ground water depth and plant structure of Miscanthus sacchariflorus during its growth period result in over 10 dB spatial and temporal variation in ASAR backscatter in HH- and HV-polarization. / Temporal profiles of C-band multi-polarized backscatter coefficients for individual land cover types over the period of December 2004 to November 2005 were studied and described in the context of the ecology and seasonal dynamics of biophysical parameters of individual land cover types. A knowledge-based hierarchical land cover mapping method was developed to quantify the dynamics of paddy rice, natural wetlands and floods using the time series of HH- and HV-backscatters. The specific phenological and ecological characteristics of wetlands including paddy rice are the most important data in mapping their spatial and temporal patterns. The classification accuracy is over 90% for water bodies, rice paddies and Carex spp. wetlands, but it is not high for tall wetlands (68%). A decision tree approach was adopted to evaluate the capacity of L-band SAR in land cover mapping by combining with optical imagery. Classification errors were mainly induced by the mixed spectrum between and covers, and lack of independent training data and validation data also caused uncertainty in the results. / The relationship of canopy height with ASAR backscattering coefficient is the most significant among the influencing factors (plant height, fresh biomass, dry biomass, vegetation water content) on radar backscattering mechanism (R2=0.9 for HH-polarization and R2=0.59 for HV-polarization) from Phragmites cummunis Trin. HH- and HV-backscatters are more sensitive to the variation of dry biomass (R2=0.76 for HH and R2=0.56 for HV) than to that of fresh biomass (R 2=0.07 for HV and R2=0.42 for HH). Plant water content plays a negative role and attenuates the backscattering signals in both polarizations. For Phragmites communis Trin. with tall stalks (over 2m) and long, blade-like leaves, HH-polarization is more sensitive to vegetation parameters than HV-polarization for C-band SAR signals. Similar to Phragmites communis Trin., ASAR backscattering coefficient in both polarizations is more sensitive to plant height and dry biomass of non-flooded Miscanthus sacchariflorus, and their regression coefficients (R2) are over 0.5 for HH-polarization and over 0.4 for HV-polarization. Plant water content has no evident effect on the variation of ASAR backscatter. HV-polarization is more sensitive to the variation of above-water canopy parameters than HH-polarization for flooded Miscanthus saccharifiorus. HH- and HV-polarized radar backscatters from Carex spp. wetlands increased significantly with the variation of plant height, fresh biomass and dry biomass, but they reach saturated when vegetation grows up to 30cm. Compared with those tall grass with stalks and long blade-like leaves, the correlation of fresh biomass with HV-polarization is more pronounced (R 2=0.78) than that with HH-polarization (R2=0.41) for Carex spp. Vegetation structure play a more important role in radar backscattering mechanism than plant water content for these three wetland species. / Sang, Huiyong. / "April 2008." / Adviser: Hui Lin. / Source: Dissertation Abstracts International, Volume: 70-03, Section: B, page: 1443. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 149-159). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Yangtze finless porpoises (YFPs) are the only fresh-water adapted porpoises in the world and they are endemic to Yangtze River system, including Poyang Lake. They are threatened by many factors, such as illegal fishing and overfishing, sand dredging, intensive shipping traffic, and pollution from agriculture and industry. Consequently, their population is decreasing at a great rate and they are listed as an endangered rare species on the red list of the International Union for Conservation of Nature (IUCN) since 1996. Moreover, a hydroelectricity project in Poyang Lake is in planning by the state of Jiangxi province, which will generate further serious threats to YFPs by cutting off their migration route and fragmenting their habitat. Therefore, it is very urgent to take some protection measures for YFPs. A special nature reserve is one possibility to protect YFPs, such as a nature reserve area, which is located in Poyang Lake. In order to find out whether a nature reserve is worthwhile, an economic analysis valuing the benefit of YFPs has been conducted. An appropriate method, the contingent valuation approach, has been chosen. The overall aim of such a contingent valuation study is to estimate the total benefits of YFPs by asking individuals’ willingness to pay for the porpoise conservation project. Because many people are unfamiliar with YFPs and the species’ total values consist of mainly non-use values, preference construction and estimating a demand function is a complex task. Therefore, the valuation workshop method, a group-based approach, which can make respondents motivated and well-informed so that they thoroughly consider the questions, provides a realistic decision-making environment. This method was selected to help respondents construct their preference. Within this study, a series of such valuation workshops were successfully organized and data and information were collected. The findings of the study have both methodological and policy-related implications. From the perspective of methodology, the important findings include: 1) Valid response rates are high enough to support further analysis and large mean WTP for porpoise conservation are obtained. Therefore, it can be concluded that the valuation workshop method as has been chosen in this study, is suitable for valuing porpoise conservation. The valuation workshop method can make people well informed about environmental goods and services, such as rare species, so that they can build their preference about them, which is quite a complex task for many individuals. IV 2) Distance effects are verified to fail to work on willingness to pay (WTP) for porpoise conservation, which is mostly driven by non-use values. Therefore, distance need not be included in the aggregation analysis of total benefits of YFPs. Similarly, the market for conservation of YFPs can be defined as the nation of China. And the sampling frame of such an evaluation of a rare species can be all the Chinese population. 3) Income effects are confirmed to be significantly influential for both Chinese respondents and German respondents. Hence, the aggregation of total values of YFPs should consider about individuals’ income levels and their ability to pay (ATP). It is inferred from the fact of smaller mean WTP in China as compared with Germany that some low-income respondents’ WTP bids are possibly distorted by their ATP, which needs further confirmation in follow-up research. In addition, there are also some policy-related implications, which are closely related with the mentioned methodological aspect: The total economic values of porpoise conservation are predicted to be appreciably huge. Definitely, their total benefits should be taken into account by politicians and decision-makers. This study makes explicit people’s attitudes and preference on the trade-off between economic growth and ecological use. The establishment of a special nature reserve for YFPs is still an open question.

Yangtze finless porpoises (YFPs) are the only fresh-water adapted porpoises in the world and they are endemic to Yangtze River system, including Poyang Lake. They are threatened by many factors, such as illegal fishing and overfishing, sand dredging, intensive shipping traffic, and pollution from agriculture and industry. Consequently, their population is decreasing at a great rate and they are listed as an endangered rare species on the red list of the International Union for Conservation of Nature (IUCN) since 1996. Moreover, a hydroelectricity project in Poyang Lake is in planning by the state of Jiangxi province, which will generate further serious threats to YFPs by cutting off their migration route and fragmenting their habitat. Therefore, it is very urgent to take some protection measures for YFPs. A special nature reserve is one possibility to protect YFPs, such as a nature reserve area, which is located in Poyang Lake. In order to find out whether a nature reserve is worthwhile, an economic analysis valuing the benefit of YFPs has been conducted. An appropriate method, the contingent valuation approach, has been chosen. The overall aim of such a contingent valuation study is to estimate the total benefits of YFPs by asking individuals’ willingness to pay for the porpoise conservation project. Because many people are unfamiliar with YFPs and the species’ total values consist of mainly non-use values, preference construction and estimating a demand function is a complex task. Therefore, the valuation workshop method, a group-based approach, which can make respondents motivated and well-informed so that they thoroughly consider the questions, provides a realistic decision-making environment. This method was selected to help respondents construct their preference. Within this study, a series of such valuation workshops were successfully organized and data and information were collected. The findings of the study have both methodological and policy-related implications. From the perspective of methodology, the important findings include: 1) Valid response rates are high enough to support further analysis and large mean WTP for porpoise conservation are obtained. Therefore, it can be concluded that the valuation workshop method as has been chosen in this study, is suitable for valuing porpoise conservation. The valuation workshop method can make people well informed about environmental goods and services, such as rare species, so that they can build their preference about them, which is quite a complex task for many individuals. IV 2) Distance effects are verified to fail to work on willingness to pay (WTP) for porpoise conservation, which is mostly driven by non-use values. Therefore, distance need not be included in the aggregation analysis of total benefits of YFPs. Similarly, the market for conservation of YFPs can be defined as the nation of China. And the sampling frame of such an evaluation of a rare species can be all the Chinese population. 3) Income effects are confirmed to be significantly influential for both Chinese respondents and German respondents. Hence, the aggregation of total values of YFPs should consider about individuals’ income levels and their ability to pay (ATP). It is inferred from the fact of smaller mean WTP in China as compared with Germany that some low-income respondents’ WTP bids are possibly distorted by their ATP, which needs further confirmation in follow-up research. In addition, there are also some policy-related implications, which are closely related with the mentioned methodological aspect: The total economic values of porpoise conservation are predicted to be appreciably huge. Definitely, their total benefits should be taken into account by politicians and decision-makers. This study makes explicit people’s attitudes and preference on the trade-off between economic growth and ecological use. The establishment of a special nature reserve for YFPs is still an open question.