| Futian Mangrove Reserve of Shenzhen Bay is the only one located in the hinterland of a city, and it is also the smallest National Nature Reserve in our country, which has many important capabilities in different aspects, such as producing organics, purifying the water and air, providing habitat and so on. With the rapid economic development of Shenzhen in 30 years, Futian mangrove wetland ecosystems was seriously affected by urban sprawl and environmental pollutions, which is accompanied with many ecological problems: the buildings block the birds passage of migratory, poor water quality causes the death of fish, the diffusion of alien species constitutes invasion, pests outbreaks frequently impacts natural reproduction of mangroves et cetera, the ecosystem exhibit the symptom of instability and unsustainability. The study analyses and evaluates the health of ecosystem in Futian Mangrove Reserve by using PSR model and AHP. Then artificial regulation was conducted in the testing area, investigating the natural restoration of mangroves continuously. Try to explore the changes of its internal structure after artificial regulation. It aims to provide a scientific basis for the restoration, protection and management of the mangrove ecosystem. The main conclusions of the study comprise the following two parts.1. The health status of mangrove ecosystem was poorThe ecosystem health assessment system of Futian Mangrove Reserve in Shenzhen Bay was built based on PSR model and used the method of AHP to assess health state of the reserve. The results show that the proportion of pressure, state, and response of the ecosystem in the system were 53.89 %, 29.73 % and 16.38 % respectively, and their health index were 0.4080, 0.5891, and 0.6037 separately. The overall system health state was sub-health, because the comprehensive health index of the ecosystem was 0.4939 and located in Ⅲ of the health level. The main reasons of above results include the following three. Firstly, the ecosystem lost some functions and its healthy level declined by the interference of urbanization in recent 30 years. In addition, the reserve was confronted tremendous external pressures from ongoing water pollution, artificial introduction plants, pests, diseases and so on. Lastly, construction and human activities, partly influenced the restoration of the ecosystem. In summary, the ecosystem was under tremendous external pressures. Internal space structure is unstable, the resilience to cope with external stress was weak, and the abilities to self-regulate and natural regeneration was poor. In recent years, people take more attentions to the mangrove, and invested more funds to management. However, its health status is still not optimistic. So we need the joint efforts of all sectors of society to help the mangrove reserve restoring to a healthy natural state.2. Artificial regulation helps local mangrove restoredThe artificial structural regulation of mangrove was carried out in the testing plots from the Futian Mangrove Reserve in Shenzhen Bay from June 2014 to March 2016. The natural restoration of mangrove plants was investigated once a month after intermediate cutting. The results showed that there were five mangrove species in the testing plots, including Kandelia obovata, Aegiceras corniculatum, Sonneratia caseolaris, Avicennia marina and Sonneratia apetala. After artificial regulation, native mangrove plants played a more important role in the natural recovery process, whereas introduced mangrove S. caseolaris grew faster competing with native mangrove species. In order to improve the competitive ability of native mangrove species, multiple artificial regulation for S. caseolaris is needed in the future. The species diversity within the testing plots was well, but they distributed unevenly. Therefore, supplementary planting was needed in the future to ensure the stability of mangrove structure. Combined with intermediate cutting and replanting, more nurturing management should also be carried out during the natural restoration of mangrove plants. |
