基于WorldView-3遥感影像的福田红树林碳储量年际变化

Interannual changes of carbon storage in mangrove forests in Futian based on WorldView-3 remote sensing images

关键词:  红树林, 碳储量, 碳密度, 遥感影像, 随机森林, 年际变化

Key words:  mangroves, carbon storage, carbon density, remote sensing image, random forest, interannual change

摘要:

红树林是热带亚热带地区特有的滨海蓝碳生态系统,然而其碳储量动态变化却鲜有报道。该文以深圳福田红树林为研究对象,基于2017年获取的WorldView-3高分辨率遥感影像以及地面样本点,采用面向对象的随机森林分类方法识别红树林优势群落冠层,反演并计算得到深圳福田红树林各优势群落面积。进一步,基于2017年、2020年和2023年3个时间段红树林群落实地调查数据,计算各优势群落碳储量,进而获得福田红树林群落碳储量空间分布及年际动态变化。结果表明:(1)随机森林算法的冠层识别总体精度为82.29%,Kappa系数为0.77; 福田红树林分布面积为93.84 hm²,其中秋茄(Kandelia obovata)分布面积最大(49.96 hm²),白骨壤(Avicennia marina)、海桑(Sonneratia caseolaris)、无瓣海桑(S. apetala)、木榄(Bruguiera gymnorhiza)的面积依次为 26.23、8.90、6.52、0.50 hm²。(2)秋茄群落总碳储量最高,其次是白骨壤、海桑和无瓣海桑,木榄群落总碳储量最低。无瓣海桑和海桑的群落碳密度呈上升趋势且无瓣海桑群落碳密度在五个优势群落中最高,秋茄群落碳密度先升后降,白骨壤群落碳密度呈下降趋势,木榄群落碳密度变化不明显。总体而言,福田红树林优势群落碳储量在2017—2023年间变化不大,秋茄、无瓣海桑和海桑群落碳固存能力较强,白骨壤群落的碳密度逐年减少,而木榄群落碳密度相对稳定。该研究结果为评估福田红树林各优势群落固碳能力提供了数据基础,并对后续红树林恢复与管理提供科学依据。

Abstract:

Mangroves are unique coastal blue carbon ecosystems in tropical and subtropical areas. However, the dynamic changes of their carbon storage are rarely reported. Based on ground sample points and WorldView-3 high-resolution remote sensing images obtained in 2017, we identified the canopy of dominant mangrove communities in Futian mangrove utilizing random forest algorithm and object-oriented classification methods, and inverted and calculated the area of each dominant community. We then calculated the carbon storage of each dominant community combining the field survey data in 2017, 2020 and 2023, and obtained the spatial distribution and interannual dynamic changes of carbon storage of mangrove communities. The results were as follows:(1)The overall accuracy of the random forest algorithm for canopy identification was 82.29%, with a Kappa coefficient of 0.77; Futian mangrove spaned an area of 93.84 hm², with Kandelia obovata having the largest distribution area of 49.96 hm², followed by Avicennia marina, Sonneratia caseolaris, S. apetala, and Bruguiera gymnorhiza, with respective areas of 26.23, 8.90, 6.52, and 0.50 hm².(2)The total carbon storage of Kandelia obovata community was the highest, followed by Avicennia marina, Sonneratia caseolaris, S. apetala, and Bruguiera gymnorhiza the lowest. The carbon density in Sonneratia apetala and S. caseolaris community showed an increasing trend, and S. apetala community revealed the highest among the five dominant communities. The carbon density of Kandelia obovata community increased first and then decreased, while Avicennia marina community showed a downward trend consistently, and carbon density in Bruguiera gymnorhiza community did not vary significantly. In summary, the carbon storage of mangrove dominant communities in Futian did not change much from 2017 to 2023. The carbon sequestration capacity of mangrove in Kandelia obovata, Sonneratia apetala and S. caseolaris communities was stronger. The carbon density of Avicennia marina community decreased year by year, while that of Bruguiera gymnorhiza community was relatively stable. These results provide foundational data for evaluating the carbon sequestration capacities of different dominant communities in Futian mangrove, in tandem with scientific support for subsequent mangrove restoration and management.