Changes in Modern Pollen Assemblages and Soil Geochemistry along Coastal Environmental Gradients in the Everglades of South Florida
Changes in Modern Pollen Assemblages and Soil Geochemistry along Coastal Environmental Gradients in the Everglades of South Florida
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DOI：
10.3389/fevo.2017.00178
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发表时间：
2018-01-25
影响因子：
3
通讯作者：
Liu, Kam-biu
中科院分区：
文献类型：
--
作者：
Yao, Qiang;Liu, Kam-biu
本研究的目的是记录现代花粉组合和土壤元素化学沿着广泛的土壤，水文和盐度梯度，包括以前没有记录的次级环境梯度的变化，在一个巨大的红树林为主的湿地地区的大沼泽地，南佛罗里达。在大沼泽地国家公园沿沿着一个内陆湿地样带和一个河口红树林样带采集了25个土壤表层样品，并进行了孢粉学和XRF分析。现代花粉光谱从采样点被分为五个先验组湿草原，松林，内陆红树林，沿海红树林，和边缘红树林，根据五种植被类型和亚环境，他们被收集。判别分析表明，所有（100%）的样本被正确地分类到他们的先验组。在广泛的范围内，现代花粉组合在不同植被类型收集的表面样品反映了在佛罗里达沿海沼泽地的主要环境梯度。在XRF结果中还记录了不同的盐度和化学梯度，并且在区域和局部尺度上捕获了这些梯度的复杂性。在区域尺度上，所有元素的浓度从陆地到沿海站点增加。在当地尺度上，XRF结果显示，在大多数化学品的浓度和Cl/Br和Ca/Ti比逐渐减少，远离鲨鱼河斯劳在每个单独的网站，这表明一个次要的河流/潮汐梯度也存在本地作为一个功能的距离，从河流，这些化学品的主要载体。这项研究提供了新的证据表明，潮洪从鲨鱼河河口是直接关系到周围的红树林的养分有效性。这些数据将加深我们对该地区植被分区背后的环境驱动因素的理解，特别是在红树林生态系统中，并填补了大沼泽地花粉数据网络的空白。
This study aims to document the changes in modem pollen assemblages and soil elemental chemistry along broad edaphic, hydrological, and salinity gradients, including a previously undocumented secondary environmental gradient, in a vast mangrove-dominated wetland region in the Everglades, South Florida. Twenty-five soil surface samples were collected along an interior wetland transect and an estuarine mangrove transect across coastal zones in the Everglades National Park and subjected to palynological and XRF analyses. Modern pollen spectra from the sampling sites were classified into five a priori groups-wet prairie, pineland, inland mangroves, coastal mangroves, and fringe mangroves, based on the five vegetation types and sub-environments from which they were collected. Discriminant analysis shows that all (100%) of the samples are correctly classified into their a priori groups. On a broad scale, the modern pollen assemblages in surface samples collected from different vegetation types reflect the primary environmental gradient in the Florida Coastal Everglades. A distinct salinity and chemical gradient is also recorded in the XRF results, and the complexity of these gradients is captured at both regional and local scales. At the regional scale, concentrations of all the elements increase from terrestrial toward coastal sites. At the local scale, XRF results show a progressive decrease in most chemical concentrations and in the Cl/Br and Ca/Ti ratios away from the Shark River Slough at each individual site, suggesting that a secondary fluvial/tidal gradient also exists locally as a function of the distance from the river, the main carrier of these chemicals. This study provides new evidence to show that tidal flooding from the Shark River Estuary is directly related to the nutrient availability in the surrounding mangrove forests. These data will deepen our understanding of the environmental drivers behind the vegetation zonation in the region, especially in the mangrove ecosystems, and fill a gap in the pollen data network for the Everglades.