Invasive Alien Plants and Invasion Risk Assessment on Pingtan Island

Pingtan Island is the largest island in Fujian Province and the fifth largest island in China. The invasion of a large number of alien plants has had a profound impact on the local ecological environment. Because the harm caused by alien invasive plants varies greatly between different ecosystems and even in different habitats, the risk assessment index system suitable for one region may not be suitable for other regions. Therefore, it is necessary to establish a risk assessment index system for invasive alien plants on Pingtan Island. Alien plant communities in different habitats were studied by means of quadrat investigation and professional literature review. Some invasive alien species were selected and compiled into a list of invasive alien plants on Pingtan Island, and their species composition, origin, flora, life forms, and habitats were statistically grouped. There were 104 species in 80 genera and 37 families of alien invasive plants. Asteraceae, Fabaceae, Amaranthaceae, and Poaceae were the main families, accounting for 26.7%, 6.7%, 6.7% and 5.8% of the total species, respectively. The geographical components of families and genera have obvious tropical properties, accounting for 51.3% and 66.6% of the total species, respectively. These originated mainly from South America and North America, accounting for 45.5% and 30.1% of the total frequency, respectively. Annual herbs, biennial herbs, and perennial herbs accounted for 84.6% of the total species. Based on a DPSIR conceptual model and an AHP method, an invasion risk assessment of 104 invasive alien plants was conducted. The ecological adaptability, habitat distribution and landscape impact of species were considered in the selection of indicators and the formulation of standards. A total of 23 high-risk invasive species were identified at level I, 37 medium-risk invasive species at level II, and 44 low-risk invasive species at level III. Lantana camara L. had the highest risk score (49), followed by Cenchrus echinatus L. (45), Spartina alterniflora Loisel. (45), and Panicum repens L. (43.5). Suggestions are put forward to prevent the invasion of alien plants on Pingtan Island and to provide a theoretical basis for promoting the healthy and stable development of the ecological environment on the island.

Evaluation of Shallow Groundwater Function in Independent Watershed Based on ArcGIS

According to the characteristics of physical geography and hydrogeology in Pingtan Island area, an independent regional groundwater evaluation system is established according to the four-layer model structure of target layer, criterion layer, attribute layer and index layer in the system. AHP (Analytic hierarchy process) is used to determine the weight value of each index in the study area, and a set of groundwater function evaluation system suitable for the island area is established. A groundwater function evaluation model with high systematic order degree is constructed and applied to the groundwater function evaluation of Pingtan Island. The results show that the groundwater in Luyangpu plain, Longwangtoupu plain, Lianjiupu plain and Qilipu plain can be developed and utilized well; The function of groundwater in the south of Aozhen and the foot of Junshan mountain is general, so we need to pay attention to the protection of ecological environment; The comprehensive function of groundwater in reclamation area, Huoshaogang salt area and Tianzhuyukou seawater intrusion area is weak, which is not suitable for exploitation and utilization. The research results are suitable for the evaluation of groundwater function in independent small areas of islands, and can provide technical support for the sustainable utilization of groundwater resources in similar islands.

Application of a Zoning Methodology for Groundwater Suitability on Islands, a Case Study of Pingtan Island, China

A groundwater function evaluation systems and associated model was applied to Pingtan Island in China, to support future development, use and protection of groundwater. Groundwater function was assigned to resource, ecology and geological environmental functions, and then further sub-divided, based on hydrogeological conditions, development status, planning and Chine policy requirements. At the same time, it is the first time to try to apply the technical requirements for the division of groundwater resources in island areas. According to the planning and utilization of groundwater resources in Pingtan Island, established a second-level system of shallow groundwater function zoning. Then, by comparing the strong and weak relationships among the groundwater resource function, ecology function, and geological environment function, developed a scoring system of the shallow groundwater function zoning. The division of shallow groundwater function zones in Pingtan Island was finally carried out. The zoning result will play an essential role in the future development, utilization, and protection of groundwater in Pingtan Island. At the same time, it provides the first example for the application of groundwater function zoning in island areas and improves the theoretical results of groundwater function zoning.

Ecological Suitability of Island Development Based on Ecosystem Services Value, Biocapacity and Ecological Footprint: A Case Study of Pingtan Island, Fujian, China

The ecological environment and resource endowment of an island are more vulnerable compared to the mainland, and special assessment and measurement of the ecological suitability for development are significant. Pingtan Island (Fujian, China) was taken as a case study. Changes in ecosystem services value and the profit-and-loss balance between ecological footprint and biocapacity were assessed using land use/cover changes based on remote-sensing images taken in 2009, 2014 and 2017, and the ecological suitability of development was measured. Results show that island development led to a decrease in the ecosystem services value and an increase in ecological footprint and biocapacity. The key ecological factors restricting the scale of island development are topography, vegetation with special functions and freshwater. Biocapacity of islands can increase not only by changing from lower-yield land types to higher-yield construction land types but also by external investment. A new measurement framework was proposed that simply and clearly reveals the ecological suitability of island development and the underlying key constraints.

DYNAMIC STATE OF ECOSYSTEM CARRYING CAPACITY UNDER ISLAND URBANIZATION: A CASE STUDY OF PINGTAN ISLAND IN THE SOUTHEASTERN COAST OF CHINA

The assessment of ecological environment during the large-scale development of islands is a major topic in the study of current coastal islands. Choosing the appropriate assessment method to evaluate the suitability of carrying capacity of islands and making relevant suggestions are significant to the sustainable development of islands. Ecological footprint method is used to analyze the ecological carrying capacity of Pingtan Island (PI) from 2005 to 2016 for promoting the coordinated rational development and construction and ecological environment of the island. Although PI is in rapid urban development and construction, the island maintains secure and stable ecological conditions. PI is used as a research case to analyze the sustainable development of the ecological environment through the carrying capacity of the island ecosystem.