Wang Wei, Xin Kun, Chen Yujun, Chen Yuechao, Jiang Zhongmao, Sheng Nong, Liao Baowen, Xiong Yanmei
Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 510520, PR China.
Guangdong Zhanjiang Mangrove National Nature Reserve Administration, Zhanjiang 524088, PR China.
Plant Divers. 2023 Jun 16;46(1):134-143. doi: 10.1016/j.pld.2023.06.006. eCollection 2024 Jan.
Salinity is among the most critical factors limiting the growth and species distribution of coastal plants. Water salinity in estuarine ecosystems varies temporally and spatially, but the variation patterns across different time scales and salinity fluctuation have rarely been quantified. The effects of salinity on floristic diversity in mangroves are not fully understood due to the temporal and spatial heterogeneity of salinity. In this study, we monitored water salinity at an interval of 10-min over one year in three mangrove catchment areas representing the outer part, middle part, and inner part respectively of Dongzhai Bay, Hainan, China. The number of mangrove community types and dominant mangrove species of the three catchment areas were also investigated. We found that the diurnal variation and dry-season intra-month variation in water salinity were driven by tidal cycles. The seasonal variation in water salinity was mainly driven by rainfall with higher salinity occurring in the dry season and lower salinity occurring in the wet season. Spatially, water salinity was highest at the outer part, intermediate at the middle part, and lowest at the inner part of the bay. The intra-month and annual fluctuations of water salinity were highest at the middle part and lowest at the outer part of the bay. The number of mangrove community types and dominant species were lowest at the outer part, intermediate at the middle part, and highest at the inner part of the bay. These results suggest that the temporal variation of water salinity in mangroves is driven by different factors at different time scales and therefore it is necessary to measure water salinity at different time scales to get a complete picture of the saline environment that mangroves experience. Spatially, lower salinity levels benefit mangrove species richness within a bay landscape, however, further research is needed to distinguish the effects of salinity fluctuation and salinity level in affecting mangrove species richness.
盐度是限制沿海植物生长和物种分布的最关键因素之一。河口生态系统中的水体盐度随时间和空间变化，但不同时间尺度上的变化模式以及盐度波动情况很少被量化。由于盐度的时空异质性，盐度对红树林植物多样性的影响尚未完全明确。在本研究中，我们在中国海南东寨港分别代表外、中、内三个部分的三个红树林集水区，对水体盐度进行了为期一年、间隔10分钟的监测。同时，我们还调查了这三个集水区的红树林群落类型数量和优势红树林物种。我们发现，水体盐度的日变化和旱季月内变化受潮汐周期驱动。水体盐度的季节变化主要受降雨驱动，旱季盐度较高，雨季盐度较低。在空间上，海湾外部的水体盐度最高，中部次之，内部最低。水体盐度的月内波动和年度波动在海湾中部最高，在外部最低。红树林群落类型数量和优势物种数量在海湾外部最少，中部次之，内部最多。这些结果表明，红树林水体盐度的时间变化在不同时间尺度上受不同因素驱动，因此有必要在不同时间尺度上测量水体盐度，以全面了解红树林所经历的盐环境。在空间上，较低的盐度水平有利于海湾景观内红树林物种的丰富度，然而，需要进一步研究以区分盐度波动和盐度水平对红树林物种丰富度的影响。
