湛江高桥红树林主要树种空间分布格局及其生物环境形成机制

Mangrove trees are distributed in the intertidal zone with low tidal energy in subtropical and tropical latitudes in China, their functions are unique and there are no substitute on maintaining ecological balance of marine ecosystem and inland ecological security. Urgent restoration and conservation measures are demanded due to the present situation that declined dramatically in the area and population degradation. It is essential for effective conservation and management to map and monitor accurately the mangrove dynamics of the pattern and species composition of mangrove forest canopies as well as its bioenvironmental forming mechanism, but little is known on mono-species level and local or regional population. The project was to be conducted in Zhanjiang Mangrove National Nature Reserve, where about 7 true mangrove species dominated the canopy of the study forest. To identify the mangrove species precisely on remote sensing data and map mangrove population patterns, multi-resolution remote sensing images were used, imagery analyses were performed such as integrated processing, bands transformation and characteristics seclection,together with tree species investigation. Resource information base of mangrove wetland would be established on the basis of the survey of per tree in the sample plots, and the attributes were to be recorded on the spatial position. The dynamics of mangrove forest stand structure were to be quantified and expressed visually through spatial explicit model according to the observation from the permanent plots of study forest, and the results would be integrated into the analysis of population pattern. The pattern of environmental factors on sediment characters as well as inundation frequency and tidal level in the sample plots were to be researched on the basis of the community investigation. An additional association analysis was performed between population spatial pattern and structure and environment factors. The bio-environmental mechanism of the spatial pattern of tree species was to be established on the association among population patterns, community structure, environmental pattern as well as sediment process under the background of global change. The results can be used on the precise management of environment resource on mangrove conservation and ecological restoration and biodiversity conservation.

我国的红树林生长于热带、亚热带的低能海岸潮间带，其对于国土生态安全和海洋生态平衡的作用无可取代。当前红树林资源锐减和种群退化的现状亟需对其进行科学的恢复和保护。红树林树种分布格局及其形成的生物环境机制是红树林资源保育和生态系统功能恢复的前提。在湛江红树林国家级自然保护区,基于多分辨率遥感影像,结合野外调查,开展红树林树种水平的精细识别研究,并对主要红树树种的水平分布格局进行精准制图；通过样地取样法建立基于每木调查的林木个体属性特征空间定位数据集，并通过空间显式模型图示量化典型群落的结构特征；根据固定样地的沉积特征、水淹时间、潮位高度等环境变量进行空间分析；通过对树种空间分布格局、群落结构和多环境变量特征进行典范对应分析，研究主要红树树种空间分布格局的生物环境形成机制和生态过程。为气候变化背景下我国红树林分布区的红树林资源保育、生态恢复和海岸带生物多样性保护等科学决策和应用实践提供数据支持。

红树林树种分布格局及其形成的生物环境机制是红树林资源保育和生态系统功能恢复的前提。研究基于高空间分辨率遥感影像Quickbird、GEOEYE-1、GF-2和无人机数据，在面向对象的基础上，通过光谱、空间、纹理等特征分析，采用分层分析逐步提取的方法，结合地面植被调查对研究区红树林进行树种水平的空间制图, 并分析了红树林种群空间动态分布。通过样地取样法，收集了树种、地径、树高、位置等数据，建立了基于每木调查的林木个体特征空间数据集，并对样地特征进行了通过空间显式表达。通过对表层沉积物取样，分析了表层沉积物的粒度特征、容重、pH、盐度、有机碳及矿质营养以及金属离子含量，并通过地统计学方法生成预测表面。结果表明：研究区红树林表层沉积物以粉粒为主，粉粒含量67.68%±12.12%，其次为沙粒，沙粒含量28.4%±12.84%，黏粒含量3.91%±0.95%；表层沉积物中有机碳（TOC）含量为2.36%±1.24%，表层沉积物中分析表明，N、P、K含量分别为955.74±437.8mg/kg、1292.23±412.45mg/kg、2792.2±841.31mg/kg；表层沉积物的金属离子中，以Al和Fe离子含量最高，分别达到35224±11034mg/kg和24192±6408mg/kg，除了Mn和Mo之外，各金属离子之间的相关性均达到极显著水平。表层沉积特征呈现明显的空间梯度，且表层沉积的有理化性质之间存在相对显著的正、负相关关系。通过对树种空间分布格局、群落结构和水系/潮沟等特征进行典范对应分析，初步阐明了研究区主要红树树种空间分布与环境的关系。表层沉积特征在不同红树林群落结构间存在差异，反映了水动力条件与红树林群落种群格局之间的关联性。研究可为气候变化背景下我国红树林分布区细尺度上红树林资源保育、动态变化和海岸带生物多样性保护等提供数据支持。