广西沿海红树林潜在适宜区变化及互花米草入侵威胁的预测

Prediction on the changes in potential suitable areas for mangroves along the coast of Guangxi and the threat from Spartina alterniflora invasion

红树林是分布于热带、亚热带潮间带的重要蓝碳生态系统之一,在我国广西沿岸广泛分布。为了更好地探究全球气候变化背景下我国红树林潜在适宜生境的变化趋势,本研究利用2021年广西沿海湿地遥感解译数据、全球海洋环境和生物气候环境数据,构建了最大熵生境分布模型,用于模拟广西沿海红树林及其入侵种互花米草潜在适宜区的空间分布,并预测极端气候变化情景下(SSP5-8.5)的变化趋势。结果表明:2021年,广西沿海现有红树林面积9136.7 hm^(2),模型预测其潜在适宜生境面积为55955.9 hm^(2),现有红树林分布区面积已基本覆盖其潜在高适宜区和近10%的中等适宜区。互花米草现有面积1320.4 hm^(2),预测其潜在高适宜区面积是现有面积的2倍,表明仍有大面积高适宜区未被互花米草占据。影响红树林现有潜在生境分布重要性最大的环境因子依次为离岸欧氏距离(62.2%)、地形凹凸指数(8.7%)、最热季平均海温(6.1%)、海底地形高程(5.6%),其潜在适宜分布区主要受地理条件影响。全球气候变化情景(SSP5-8.5)下,预测红树林的潜在适宜区面积将增加5.3%,互花米草的潜在适宜区将减少3.1%。当前和未来气候情境下,红树林和互花米草的适应生境重叠区域面积占红树林潜在适宜生境的比例相当,分别为15.2%和14.5%。未来仍需加强本区红树林的保护和生态修复,预防互花米草进一步入侵的挑战依旧严峻。

As one of the important blue carbon pools in tropical and subtropical intertidal zones,mangroves are widely distributed along the coast of Guangxi in China.To deeply explore the variations of potential suitable habitats for mangroves in China under the background of climate change,based on remote sensing interpretation data of coastal wetlands in Guangxi,global marine environment and bioclimatic environment data in 2021,we constructed a maximum entropy habitat distribution model to simulate the spatial distribution of potential suitable areas for mangroves and the invasive species,Spartina alterniflora,along the coast of Guangxi,and predicted the patterns under extreme climate change scenarios(SSP5-8.5).The results showed that the interpreted area of mangrove forests along the coastline of Guangxi was 9136.7 hm2 in 2021,while the predicted area of potential suitable habitat area was 55955.9 hm2.Current distribution area of mangroves had basically covered its potential high suitability area and nearly 10%of the moderate suitability area.The current area of S.alterniflora was 1320.4 hm2,and the predicted area of potential high suitability area was twice of current area,indicating that there was still a large proportion of high suitability area that was not occupied by S.alterniflora.The most important environmental factors driving the distribution of potential habitats in mangroves were offshore Euclidean distance(62.2%),terrain deviation index(8.7%),average sea surface temperature in the hottest season(6.1%),and seabed terrain elevation(5.6%).The contribution of geographical conditions on mangrove distribution was predominant.Under the climate change scenario(SSP5-8.5),potential suitable area for mangroves would increase by 5.3%,while that for S.alterniflora would decrease by 3.1%.The overlapping proportion of the potential suitable area for mangroves and S.alterniflora was similar under current and SSP5-8.5 scenarios,being 15.2%and 14.5%,respectively.In the future,it is necessary to strengthen the protection and ecological restoration of mangroves along the coast of Guangxi and there is great challenge for preventing further invasion of S.alterniflora.