基于景观特征的广西典型红树林湿地生态系统健康评价

结合红树林景观特征,评价广西壮族自治区红树林典型分布区(珍珠湾、茅尾海、丹兜海)的生态系统健康状况。通过对不同景观格局与过程的指标进行分析,筛选出面积周长比分维数(PAFRAC)、中高级重要性斑块比例、等效面积概率连接度指数(ECA)指标来表征景观特征,并进一步结合水环境、生物残毒、栖息地和生物现状构建生态健康评价模型。结果表明:珍珠湾和丹兜海景观破碎化程度较小,茅尾海景观破碎化程度相对较高;珍珠湾、茅尾海、丹兜海的ECA依次为0.82×10~7、0.76×10~7、0.59×10~7,但丹兜海的重要栖息地斑块分布最多。对比分析表明,耦合了景观指数的生态系统健康评价结果符合实际,珍珠湾和丹兜海均处于健康状态,而茅尾海处于亚健康状态。

Ecosystem health evaluation of mangrove wetlands in Guangxi based on landscape characteristics

The present paper devotes itself to the ecosystem health evaluation of mangrove wetlands in Guangxi Zhuang Autonomous Region to promote the ecosystem health of the region from the point of view of the landscape features.As is well known,the ecosystem health of mangrove wetlands is very important to sustain the development of the coastal ecological environment,particularly for the typical distribution areas,such as Zhenzhu Bay,Maowei Sea and Dandou Sea in Guangxi Zhuang Autonomous Region.It is just for the purpose to promote the successful development of the local healthy ecosystem that we have engaged in the given analysis and evaluation in support of the mangrove landscape patterns and the ecological balance maintenance.It is also for the aforementioned purpose that we have chosen the number of patches (NP),the patch density (PD),the largest patch index (LPI),the landscape shape index(LSI),and the perimeter-area fractal dimension (PAFRAC) to describe the landscape patterns,while the equivalent connected area (ECA) and relative importance value of the patch (dPC) are the characteristic features of the landscape connectivity.What is more,through a contrastive analysis of the different indexes,we have also identified and determined the proportions of the intermediate and senior patch importance,ECA and PAFRAC as the proxies of landscape characteristic indexes illustrated in the coastal ecosystem health evaluation model,which consists of two parts,the environmental factors (30％) and the ecological factors(70％),representing the features of the water environment,the organism-residual hazards,the habitat quality and the biological state.Finally,we have also assigned the above said ecosystem health indexes of the above three study areas in line with the ranges of the specific indexes of the above mentioned factors.Thus,the results of our study indicate that,in 2014,Zhenzhu Bay and Dandou Sea should be attributed to the areas well done in preserving the landscape ecological integrity,for they were less affected by the fragmentation of the patches.However,the spatial landscape of Maowei Sea still remains rather highly fragmented in the regard of the landscape pattern indexes,with ECA values of Zhenzhu Bay,Maowei Sea,Dandou Sea being 0.82 × 107,0.76 × 107 and 0.59 × 107,respectively,when the dispersal distance is 2 km.In contrast,Dandou Sea enjoys the highest percentage of the important habitat patch(33.33％) which contributes more fully to the local landscape connectivity.Thus,in accordance with the ecosystem health model,Zhenzhu Bay should be regarded as an area all in healthy state,while water environment and the biological state of Maowei Sea are sub-healthy.In addition,Dandou Sea is also relegated to a sub-healthy biological state.In spite of this,on the whole,Zhenzhu Bay and Dandou Sea can all be taken as healthy areas,while Maowei Sea remains in the sub-health state.Further comparison will show that it is more realistic to assess the ecosystem health from the point of view of the landscape characteristics.