Recently, ZHU Bozhong, a graduate student in our research group, published a research paper titled "Long-Term Changes in the Land–Ocean Ecological Environment in Small Island Countries in the South Pacific: A Fiji Vision" in "Remote Sensing". The corresponding author is Researcher BAI Yan in our research group.
Most of the small island countries in the South Pacific have unique geographical features such as being surrounded by sea and having a small land area. They are typical "ecologically fragile areas" and are one of the fastest and most sensitive interfaces between global changes and the dynamic effects of land and sea. The system has high sensitivity and low stability. Coupled with the coupling of various pressures such as human activities and natural changes, the ecological environment of small island countries presents complex and diverse fragile sensitivities, which greatly affects their sustainable development. This paper takes Fiji, one of the South Pacific island countries, as the research area. Based on multi-source satellite remote sensing data, it reports its 30-year land use change data from 1991 to 2019 (Figure 1) and atmospheric water environment change data from 1993 to 2019 (Figure 2), and discussed the impact of global climate change and human activities on the ecological environment of small island countries in the South Pacific.
Figure 1 Changes in land use types in Fiji from 1991 to 2019: (a) 1991; (b) 2002; (c) 2004; (d) 2005; (e) 2011; (f) 2014; ( g) 2016; (h) 2019
Figure 2 Long-term changes in atmospheric water environment parameters: (a) sea level height anomaly; (b) sea surface temperature; (c) atmospheric carbon dioxide partial pressure; (d) sea surface chlorophyll concentration; (e) colored dissolved organic matter concentration; (f) Seawater transparency.
The study found that the dynamic changes in Fiji's land and sea in the past 30 years can be divided into three stages: from 1991 to 2002, Fiji's vegetation was at a high level, about 14,000 km2, accounting for 70% of the total land coverage area, while the bare land area was relatively small , about 2,500 km2 (10%); during this period, the sea level height, sea surface temperature, and atmospheric carbon dioxide concentration in the sea areas around the island were relatively low. From 2002 to 2014, affected by the development of forestry and tourism, the vegetation area dropped to a minimum of 13,320 km2, and the bare land area increased to a maximum of 4,030 km2. During the same period, land use changes in the basin and runoff erosion combined, and Fiji's three major estuaries The sea surface chlorophyll concentration in adjacent sea areas is slightly higher than in other periods, the seawater transparency is at a low level, and the sea level rise rate is at a high stage. The area of coral reefs in the sea areas around Fiji has significantly reduced, especially the area of bare land and land runoff distribution. In the waters around Vanua Levu, the area of coral reef loss accounted for 51.13% of the total area of loss during this period. From 2014 to 2019, the ecological and environmental conditions of Fiji's land and sea have recovered. The areas of forests and coral reefs have increased by 884 km2 and 482 km2 respectively, and the area of bare land has decreased by 1,154 km2. During the same period, due to the influence of short-term climate shocks such as ENSO, sea surface temperatures have shown an abnormal decline. , the colored dissolved organic matter increases, and the transparency of seawater decreases (Figure 3).
Figure 3 Analysis of changes in coral reefs in the waters around Fiji under the influence of global changes and human activities based on multi-source satellite remote sensing data
Citation: Zhu, B.; Bai, Y.; He, X.; Chen, X.; Li, T.; Gong, F. Long-Term Changes in the Land–Ocean Ecological Environment in Small Island Countries in the South Pacific : A Fiji Vision. Remote Sens. 2021, 13, 3740.
