ZHOU Yuanhui1,2,3, ZHANG Zhonghua1,2, LI Jie1,2,3, LIU Xiong4, HU Gang1,2
(1.Key Laboratory of Beibu Gulf Environment Change and Resources Utilization of Ministry of Education, Nanning Normal University, Nanning 530001,China;
2.The Collaborative Innovation Center of the Ecological Environment and Integration Development in the Xijiang River Basin, Nanning Normal University, Nanning 530001,China;
3.School of Geography and Planning, Nanning Normal University, Nanning 530001,China;
4.Sea-Area Use Dynamic Monitoring Center of Fangchenggang City, Fangchenggang 538001,China)
Abstract: The mangrove wetland ecosystem is a coastal ecological key area that combines ecological characteristics of land and marine. This study selected the natural mangrove community in the Guangxi Beilun Estuary Nature Reserve and analyzed contents of C, N and P, and their stoichiometric ratios in leaves of four mangrove plants (Bruguiera gymnorrhiza, Aegiceras corniculatum, Kandelia obovate and Avicennia marina) and samples of two soil profiles (0-10cm and 30-40cm). The results showed that: (1) the average contents of C, N and P in leaves of four mangrove plants were 492.49, 13.39 and 1.35 mg/g, respectively, and the order of C contents was A. corniculatum > K. obovate > B. gymnorrhiza > A. marina, and the order of N and P contents was A. marina > K. obovate > A. corniculatum > B. gymnorrhiza, ratios of C:N, C:P, and N:P in leaves were 39.04, 414.63, and 10.47, respectively, indicating that mangrove plants in the Beilun Estuary, whose growth is restricted by N, have high carbon sinking capacity; (2) average contents of C, N and P in soils were 28.65, 1.04 and 0.22 mg/g, respectively, and N and P contents in soils of 0-10 cm were greater than those in soils of 30-40 cm, while C contents in soils showed an opposite trend, contents of N and P and ratios of C:N and C:P were different very significant between two soil profiles; (3) correlations of N and P contents in leaves and soils were not significant; significant or very significant negative correlations were found among soil P contents, C contents in leaves and ratios of C:P and N:P in leaves, while soil N contents significantly positively correlated with C:P ratios in leaves and very significantly negatively correlated with N:P ratios in leaves. These results may be related to physiological and ecological characteristics of mangrove plants and estuarine coastal environment conditions, such as tidal, microtopography and so on.
Key words: mangrove; ecological stoichiometry; C:N:P ratio; nutrient limitation; Beilun Estuary
EARTH AND ENVIRONMENT Vol.48, No.1, Tot No.333, 2020, Page 58-65