Changes within a South Carolina Coastal Wetland Forest in the Face of Rising Sea Level

William Conner,Stefanie Whitmire,Richard Stalter,John Baden,Jamie Duberstein

doi:10.3390/f13030414

William Conner, Stefanie Whitmire + Show 3 more

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https://doi.org/10.3390/f13030414

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Abstract

Rising sea levels and increasing salinity are impacting coastal forests of the Southern U.S. Forest productivity and composition was studied from 2014 to 2020 in paired plots (20 × 25-m) along a porewater salinity gradient (0, 0.8, 2.6, 4.6 PSU). Aboveground net primary productivity was estimated by summing annual litterfall and woody growth. In addition, voucher specimens for each vascular plant species were collected. Productivity differed in forest communities across the salinity gradient averaging 1081, 777, 694, and 613 g m−2 yr−1 in fresh, low-salt, mid-salt, Freshwater forest communities and high-salt sites, respectively. The vascular flora consisted of 144 species within 121 genera and 57 families. Although salinity in Strawberry Swamp is currently declining, it hasn’t reached levels low enough to reverse the loss of forested wetlands. With projections of continuing sea level rise and increasing salinity intrusions, tree regeneration and growth will continue to decline as the forest transitions into marsh.

Highlights

Tidal freshwater forested wetlands (TFFWs) are unique forested wetland ecosystems whose structure is a result of flooding, salinity, and topographical gradients [1–4]
It is important to understand how productivity of TFFWs is affected by tidal fluctuations, local precipitation, and freshwater inputs [12,13]
Strawberry Swamp does not experience the effects of daily tidal fluctuations as other TFFW often do

Summary

Introduction

Tidal freshwater forested wetlands (TFFWs) are unique forested wetland ecosystems whose structure is a result of flooding, salinity, and topographical gradients [1–4]. TFFWs have relatively high primary productivity, likely due to the hydrological pulsing these systems experience from tides [7,8]. This productivity, combined with their broad distribution along the U.S Gulf and Atlantic coasts [9], Europe, Central America, and the Amazon [10], means there is the potential for large amounts of carbon (C) to be stored in these areas [11]. It is important to understand how productivity of TFFWs is affected by tidal fluctuations, local precipitation, and freshwater inputs [12,13]. It is forecast that climate change will cause sea level rise rates to increase, as well as cause changes in local precipitation and watershed runoff [22,23]. The greatest threat to TFFWs as sea level rises is increased flooding and decreased flushing

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