寒害后珠海淇澳岛红树林群落水土生要素的CCA分析

选取2008年寒害后和恢复重建5年后红树林群落水土生要素进行纵向对比,选取水域pH、化学需氧量(COD)、溶解氧(DO)、总悬浮物(TSS)、总无机氮(TIN)、正磷酸盐(PO_4-P)等水环境指标和(S)pH、氧化还原电位(Eh)、有机质(OM)等沉积物指标进行不同类型红树林群落间的横向对比。自变量指标中水环境指标所占比例较大,约为2—3,弥补了红树林湿地植被、沉积物和水文等3个自然因素中水文条件研究较为缺乏的现状。结合各类红树林群落水、土、生三要素进行典范对应分析(CCA)的结果表明:1)典范对应分析方法用于分析淇澳岛大围湾各类红树林典型群落寒害后及寒害5年后的群落生物过程特征与各种生境因子间的相关关系,效果良好,前4组自变量的典型变量可以解释标准变量中绝大部分(约80%以上)的信息。2)恢复重建5年后,淇澳岛大围湾各类红树林群落中中潮位的无瓣海桑(Sonneratia apetala)群落和高潮位的桐花树(Aegiceras comiculatum)群落拓展最快,面积分别增加26.58hm~2和23.1 hm~2,而互花米草(Spartina alterniflora)群落因无瓣海桑群落的扩张而受到抑制,面积下降31.51hm~2。3)水域pH、沉积物(S)pH、OM、DO、COD等水土指标与冠幅、胸径、基径、盖度和高度等生物过程指标依次正相关,而PO_4-P、TSS和TIN等水域指标与生物过程指标依次负相关。4)珠海淇澳岛大围湾红树林湿地生态系统对水域悬浮物和营养元素的固定效果明显,但其植被生物过程受水土因素,尤其是水文因素,影响较大,其中影响最大的生境因素是pH值(包括水域pH值和沉积物(S)pH值)。低中潮位、中性至弱碱性的表层沉积物生境条件较为适合无瓣海桑和老鼠簕(Acanthus ilicifolius)等红树植物群落的初期恢复。

The CCA analysis of the hydrology, sediment and vegetation factors of mangrove communities in Zhuhai Qiao Island after a cold damage

In this study, the hydrology, sediment and vegetation factors of mangrove communities in Qiao Island after a cold damage in 2008 and five years after the recovery and reconstruction were selected and compared longitudinally. Furthermore, the water environment indicators (e.g., water pH, COD, DO, TSS, TIN and PO₄-P) and the sediment indicators (e.g., sediment pH, Eh and OM) of different types of mangrove communities were compared laterally. With the attempt to make up for the lack of research on hydrology, sediment and vegetation process factors (especially the hydrological) of the mangrove wetland, this paper selects some water environment indicators which account for a larger proportion (about two-thirds) of the independent variables. On this basis, the canonical correlation analysis was conducted by combining the hydrology, sediment and vegetation process indexes of various types of mangrove communities. The results shows that the canonical correlation analysis is used for explaining the relationship between biological process characteristics and habitat factors of the various types of mangrove communities in Qiao Island Dawei Bay after a cold damage and five years after the recovery and reconstruction. The effect is good. The first four canonical correlation coefficients of the independent variables could explain the vast majority (above 80%) of the information of standard variables. The various types of mangrove communities in Qiao Island Dawei Bay all exhibit different levels of growth after five years'' reconstruction, among which Sonneratia apetala community in the medium tide and Aegiceras corniculatum-Phragmites australis community in the high tide expand the fastest. The area of them has increased 26.58hm² and 23.1hm² respectively. However, the area of Spartina alterniflora community has decreased 31.51hm², which is owing to the expansion and suppression of the mangrove communities of Sonneratia apetala etc. The water pH, sediment pH, OM, DO and COD show strong positive correlation with the crown breadth, diameter at breast height, base diameter, height and coverage, and other factors, while the water environment indicators such as PO₄-P, TSS and TIN are negatively related to the biological process variables successively. The suspended solids and nutrient elements of the waters could be fixed by the mangrove wetland ecosystem in Zhuhai Qiao Island Dawei Bay obviously. Nevertheless, the biological process of vegetation has been affected by hydrology and sediment factors (especially the hydrological) greatly, among which pH (including water pH and sediment pH) could make the greatest impact. The low-medium tide and surface sediment''s habitat conditions of neutral and weak alkalinity are more suitable for the early recovery of mangrove plant community of Sonneratia apetala, Acanthus ilicifolius etc.