Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, USA.
Department of Biology, University of Florida, Gainesville, FL, USA.
Glob Chang Biol. 2017 Dec;23(12):5383-5397. doi: 10.1111/gcb.13805. Epub 2017 Jul 26.
Sea level rise elicits short- and long-term changes in coastal plant communities by altering the physical conditions that affect ecosystem processes and species distributions. While the effects of sea level rise on salt marshes and mangroves are well studied, we focus on its effects on coastal islands of freshwater forest in Florida's Big Bend region, extending a dataset initiated in 1992. In 2014-2015, we evaluated tree survival, regeneration, and understory composition in 13 previously established plots located along a tidal creek; 10 plots are on forest islands surrounded by salt marsh, and three are in continuous forest. Earlier studies found that salt stress from increased tidal flooding prevented tree regeneration in frequently flooded forest islands. Between 1992 and 2014, tidal flooding of forest islands increased by 22%-117%, corresponding with declines in tree species richness, regeneration, and survival of the dominant tree species, Sabal palmetto (cabbage palm) and Juniperus virginiana (southern red cedar). Rates of S. palmetto and J. virginiana mortality increased nonlinearly over time on the six most frequently flooded islands, while salt marsh herbs and shrubs replaced forest understory vegetation along a tidal flooding gradient. Frequencies of tidal flooding, rates of tree mortality, and understory composition in continuous forest stands remained relatively stable, but tree regeneration substantially declined. Long-term trends identified in this study demonstrate the effect of sea level rise on spatial and temporal community reassembly trajectories that are dynamically re-shaping the unique coastal landscape of the Big Bend.
海平面上升通过改变影响生态系统过程和物种分布的物理条件，引发了沿海植物群落的短期和长期变化。虽然海平面上升对盐沼和红树林的影响已经得到了很好的研究，但我们关注的是它对佛罗里达州大弯地区淡水森林沿海岛屿的影响，扩展了始于 1992 年的数据集。在 2014-2015 年，我们评估了 13 个先前建立的位于潮汐溪沿岸的测站的树木存活率、更新和林下植被组成；其中 10 个测站位于被盐沼环绕的森林岛屿上，3 个位于连续森林中。早期研究发现，由于潮汐洪水增加而导致的盐胁迫阻止了经常被洪水淹没的森林岛屿中的树木更新。1992 年至 2014 年间，森林岛屿的潮汐洪水增加了 22%-117%，与树种丰富度、更新和优势树种萨巴尔棕榈（白菜棕榈）和南方红柏（南方雪松）的存活率下降相对应。在六个最常被洪水淹没的岛屿上，S. palmetto 和 J. virginiana 的死亡率随着时间的推移呈非线性增加，而盐沼草本植物和灌木则沿着潮汐洪水梯度取代了森林林下植被。连续森林林分中的潮汐洪水频率、树木死亡率和林下植被组成相对稳定，但树木更新显著下降。本研究中确定的长期趋势表明，海平面上升对空间和时间群落再组装轨迹的影响正在动态重塑大弯地区独特的沿海景观。
