Assessing the Atmospheric Oxygen Balance in a Region of Rapid Urbanization: A Case Study in the Pearl River Delta, China

Co-Creation Hub Is the First Step for the Successful Creation of a Unified Urban Ecosystem-Kaunas City Example

The identification of the main steps for the creation of a unified ecosystem from the institutional point of view and the framework for ecosystem design is presented and discussed. Based on the expertise and the knowledge gained during the time when the ELISE project had been implemented, a unified Kaunas city ecosystem is being designed using the Ecosystem Map method. As the review of the ELISE project reports helped to identify the main steps of each project partner in building ecosystems’ networks, Kaunas city chose to create a co-Creation Hub (c-CH), which is the first step in developing an ecosystem management model. The main tasks of such a hub are listed, and should involve the preparation of a long-term action plan involving not only the coordination of the stakeholder meetings, organisation of seminars, the preparation of new materials, and methodology but also the development of a clear strategy for each stakeholder based on national economy and government and municipality policies. The role of the c-CH is to ensure the ease of cooperation and knowledge distribution among stakeholders within the city, public authorities, and the national government. This approach could become a fundamental background tool for the regional and/or city municipal and stakeholder-based creation and development of unified ecosystem development.

Declining Oxygen Level as an Emerging Concern to Global Cities

Rising CO₂ concentration and temperatures in urban areas are now well-known, but the potential of an emerging oxygen crisis in the world's large cities has so far attracted little attention from the science community. Here, we investigated the oxygen balance and its related risks in 391 global large cities (with a population of more than 1 million people) using the oxygen index (O_I), which is the ratio of oxygen consumption to oxygen production. Our results show that the global urban areas, occupying only 3.8% of the global land surface, accounted for 39% (14.3 ± 1.5 Gt/yr) of the global terrestrial oxygen consumption during 2001-2015. We estimated that 75% of cities with a population more than 5 million had an O_I of greater than 100. Also, cities with larger O_I values were correlated with more frequent heatwaves and severe water withdrawals. In addition, cities with excessively large O_I values would likely experience severe hypoxia in extremely calm weather. Thus, mitigation measures should be adopted to reduce the urban O_I in order to build healthier and more sustainable cities.

Coastline Fractal Dimension of Mainland, Island, and Estuaries Using Multi-temporal Landsat Remote Sensing Data from 1978 to 2018: A Case Study of the Pearl River Estuary Area

The Pearl River Estuary Area was selected for this study. For the past 40 years, it has been one of the most complex coasts in China, yet few studies have analyzed the complexity and variations of the area’s different coastlines. In this investigation, the coastlines of the Pearl River Estuary Area were extracted from multi-temporal Landsat remote sensing data from 1978, 1988, 1997, 2008, and 2018. The coastline of this area was classified into mainland, island, and estuarine. To obtain more detailed results of the mainland and island, we regarded this area as the main body, rezoned into different parts. The box-counting dimension was applied to compute the bidimensional (2D) fractal dimension. Coastline length and the fractal dimension of different types of coastline and different parts of the main body were calculated and compared. The fractal dimension of the Pearl River Estuary Area was found to have increased significantly, from 1.228 to 1.263, and coastline length also increased during the study period. The island and mainland showed the most complex coastlines, while estuaries showed the least complexity during the past forty years. A positive correlation was found between length and 2D-fractal dimension in some parts of the study area. Land reclamation had the strongest influence on fractal dimension variations.

Effects of urbanization on productivity of terrestrial ecological systems based on linear fitting: a case study in Jiangsu, eastern China

The terrestrial ecosystem productivity and foundation of regional ecosystem services have been significantly influenced by recent urbanization processes. This study assesses the changes in terrestrial ecosystem productivity in Jiangsu from the years of 2000 to 2015 in response to the urbanization. A linear model that incorporates the traditional equalization method is proposed to improve the estimation accuracy of net primary productivity (NPP) loss. Results revealed that the land area of urban construction expanded rapidly during the research period to encompass an area of 8672.8 km². The rate of expansion was highest during 2005-2010. Additionally, the expansion rate of urban construction land was considerably higher in southern Jiangsu compared to the northern areas. The NPP exhibited a rising tendency from the year of 2000 to 2015, and varied from 33.30 to 40.23 Tg C/y. It was higher in the central parts, which include the cities of Yancheng and Nantong. The increase in urban construction land has resulted in a significant reduction in the terrestrial ecosystem productivity, i.e. a cumulative NPP loss of 2.55-2.88 Tg C during the research period. The NPP losses due to the conversion from cropland to constrction land were the highest, followed by the wetland. The work in this paper indicates that the rate of future productivity losses in terrestrial ecosystem in northern Jiangsu would be faster than the southern areas.