Nothing Special   »   [go: up one dir, main page]
You seem to have javascript disabled. Please note that many of the page functionalities won't work as expected without javascript enabled.
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
4.4
2.4
Journals
Forests
Special Issues
Coastal Forest Dynamics and Coastline Erosion, 2nd Edition
share announcement

Coastal Forest Dynamics and Coastline Erosion, 2nd Edition

A special issue of Forests (ISSN 1999-4907). This special issue belongs to the section "Forest Hydrology".

Deadline for manuscript submissions: closed (30 June 2024) | Viewed by 6878

Special Issue Editors

Dr. William H. Conner

E-Mail Website
Guest Editor
Belle W. Baruch Institute of Coastal Ecology and Forest Science, Clemson University, P.O. Box 596, Georgetown, SC 29442, USA
Interests: forested wetland ecology; wetland management; wetland creation and restoration; effects of man and nature on natural environments; wetlands for wastewater treatment; estuarine/upland connections; changing land-use impacts on natural systems
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Thomas J. Dean

E-Mail Website
Guest Editor
School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA
Interests: crown dynamics; stem mechanics; population biology; competition; size–density relationships
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

A combination of anthropogenic and natural factors threaten the coastline and the forests that lie between the coast and the uplands. Various transportation, navigation, and flood control projects have greatly altered hydrology, leading to drying in the upper reaches of flood plains and permanent flooding in the lower reaches. Rising sea levels encroach on coastal forests as well, and salt water has intruded into normally freshwater swamps. These alterations are favoring species changes in the upper reaches and conversion to marsh in the lower regions. To forestall these changes, more information is needed to support efforts to maintain coastal forests, to regenerate and restore coastal forests for the near future, and to identify environmental conditions that need to be created when planning rehabilitation projects.

The aim of this Special Issue is to create a collection of articles addressing the basic and applied ecology of coastal species, how they respond to changes in their habitat, and analyses of rehabilitation projects. The scope of the Special Issue includes species commonly associated with coastal forests, the threats facing coastal forests with specific examples, and management practices used to regenerate and tend coastal forests.

The topics of manuscripts we are soliciting include the following, involving coastal species and changes in their habitat:

  • Silviculture;
  • Production ecology;
  • Ecohydrology;
  • Tolerance;
  • Restoration case studies.

Dr. William H. Conner
Prof. Dr. Thomas J. Dean
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Forests is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • coastal forests
  • sea level rise
  • silviculture
  • ecohydrology
  • tolerance

Benefits of Publishing in a Special Issue

  • Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • e-Book format: Special Issues with more than 10 articles can be published as dedicated e-books, ensuring wide and rapid dissemination.

Further information on MDPI's Special Issue polices can be found here.

Published Papers (6 papers)

Download All Papers
Order results
Result details
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:

Research

29 pages, 8791 KiB  
Article
Leaf Physiological Responses and Early Senescence Are Linked to Reflectance Spectra in Salt-Sensitive Coastal Tree Species
by Steven M. Anderson, Emily S. Bernhardt, Jean-Christophe Domec, Emily A. Ury, Ryan E. Emanuel, Justin P. Wright and Marcelo Ardón
Forests 2024, 15(9), 1638; https://doi.org/10.3390/f15091638 - 17 Sep 2024
Viewed by 779
Abstract
Salt-sensitive trees in coastal wetlands are dying as forests transition to marsh and open water at a rapid pace. Forested wetlands are experiencing repeated saltwater exposure due to the frequency and severity of climatic events, sea-level rise, and human infrastructure expansion. Understanding the [...] Read more.
Salt-sensitive trees in coastal wetlands are dying as forests transition to marsh and open water at a rapid pace. Forested wetlands are experiencing repeated saltwater exposure due to the frequency and severity of climatic events, sea-level rise, and human infrastructure expansion. Understanding the diverse responses of trees to saltwater exposure can help identify taxa that may provide early warning signals of salinity stress in forests at broader scales. To isolate the impacts of saltwater exposure on trees, we performed an experiment to investigate the leaf-level physiology of six tree species when exposed to oligohaline and mesohaline treatments. We found that species exposed to 3–6 parts per thousand (ppt) salinity had idiosyncratic responses of plant performance that were species-specific. Saltwater exposure impacted leaf photochemistry and caused early senescence in Acer rubrum, the most salt-sensitive species tested, but did not cause any impacts on plant water use in treatments with <6 ppt. Interestingly, leaf spectral reflectance was correlated with the operating efficiency of photosystem II (PSII) photochemistry in A. rubrum leaves before leaf physiological processes were impacted by salinity treatments. Our results suggest that the timing and frequency of saltwater intrusion events are likely to be more detrimental to wetland tree performance than salinity concentrations. Full article
(This article belongs to the Special Issue Coastal Forest Dynamics and Coastline Erosion, 2nd Edition)
►▼ Show Figures

Figure 1

Figure 1
<p>Plant communities in coastal, non-tidal freshwater wetlands are comprised of salt-sensitive forest, shrub–scrub, and salt-tolerant marsh species. Soil salinization varies in response to heterogeneous microtopography and response to gradients in elevation and vegetation abundance from estuarine waters to tree-dominated wetlands. Coastal tree species that dominate forested wetlands have species-specific sensitivity to salinization and are therefore susceptible to ecosystem transition. Several of these tree species included in this study are deciduous hardwoods (<span class="html-italic">Acer rubrum</span>, <span class="html-italic">Nyssa sylvatica</span>, and <span class="html-italic">Quercus nigra</span>) and evergreen or deciduous conifers (<span class="html-italic">Juniperus virginiana</span>, <span class="html-italic">Taxodium distichum</span>, and <span class="html-italic">Pinus taeda</span>). The background image is a modification of a photograph taken by S. Anderson in Swan Quarter National Wildlife Refuge in North Carolina, USA.</p> Full article ">Figure 2
<p>(<b>a</b>) Conceptual drawing of one basin with one tree of each of the six tree species and the groundwater level (8–16 cm) that was maintained in each of the 22 basins from the greenhouse study. (<b>b</b>) A schematic of the number of replicate trees within each experimental treatment (in parts per thousands; ppt) for each species. The two primary treatments (control and 3 ppt) highlighted in grey ranging from 4–8 replicates per species and individuals for intermediate and high salinity treatments for regression analysis only. All 118 trees were grown in the same greenhouse and the same basin setup.</p> Full article ">Figure 3
<p>Specific conductance (µs/cm) of (<b>a</b>) basin groundwater and (<b>b</b>,<b>c</b>) tree pot soils measured from 1 May to 26 September 2018, averaged across all experimental basins within each treatment over the entire 6-month experiment. Soil-specific conductance measured at (<b>b</b>) 5 cm and (<b>c</b>) 10 cm depths from the soil surface. The two replicated treatments are in color: control (green) and orange (3 ppt). All other intermediate (0.5, 1, and 2 ppt) and high (4, 5, and 6 ppt) treatments are in a gradient of grey circles and dotted lines (0.5 and 4 ppt), squares and dashed lines (1 and 5 ppt), or triangles and solid lines (2 and 6 ppt). Non-replicated intermediate treatments (in grey) are shown to highlight trends only. Error bars are the standard deviation for both replicated treatments (control and 3 ppt). The vertical shaded bars in the soil conductance (<b>b</b>,<b>c</b>) noted by the asterisks above the figure indicate salt additions, or pulses, added to the groundwater of each treatment basin.</p> Full article ">Figure 3 Cont.
<p>Specific conductance (µs/cm) of (<b>a</b>) basin groundwater and (<b>b</b>,<b>c</b>) tree pot soils measured from 1 May to 26 September 2018, averaged across all experimental basins within each treatment over the entire 6-month experiment. Soil-specific conductance measured at (<b>b</b>) 5 cm and (<b>c</b>) 10 cm depths from the soil surface. The two replicated treatments are in color: control (green) and orange (3 ppt). All other intermediate (0.5, 1, and 2 ppt) and high (4, 5, and 6 ppt) treatments are in a gradient of grey circles and dotted lines (0.5 and 4 ppt), squares and dashed lines (1 and 5 ppt), or triangles and solid lines (2 and 6 ppt). Non-replicated intermediate treatments (in grey) are shown to highlight trends only. Error bars are the standard deviation for both replicated treatments (control and 3 ppt). The vertical shaded bars in the soil conductance (<b>b</b>,<b>c</b>) noted by the asterisks above the figure indicate salt additions, or pulses, added to the groundwater of each treatment basin.</p> Full article ">Figure 4
<p>Summary table of effect sizes (Hedge’s g) between control and 3 ppt salinity treatments for plant performance parameters including leaf mass and area (LM and LA), specific leaf area (SLA), leaf dry matter content (LDMC), leaf percent carbon and nitrogen (%C and %N), leaf carbon–nitrogen ratio (C:N), aboveground biomass (AGB), belowground biomass (BGB), height and diameter growth rates (HGR and DGR), and root-to-shoot ratio/root mass fraction (RSR). Dark-shaded cells indicate a large mean increase or decrease in effect sizes compared to controls. Light-shaded cells indicate a small or medium effect size compared to control. If differences in means were significant (<span class="html-italic">p</span> ≤ 0.05), values are bold. White cells indicate no difference.</p> Full article ">Figure 5
<p>(<b>a</b>) The relationship between osmotic potential (Ψ<sub>π</sub>, MPa) of the groundwater treatment solutions (NaCl) after the second salinity dose and the difference between Ψ<sub>π</sub> and predawn leaf water potential (Ψ<sub>pd</sub>, MPa) across all species and salinity treatments. Each color and shape combination represents Ψ<sub>π</sub> and Ψ<sub>pd</sub> for each species. The horizontal arrow (color gradient from green to red) represents the direction of salinity increase as Ψ<sub>π</sub> becomes more negative. The vertical arrow in the panel shows that as Ψ<sub>pd</sub> decreases in tandem with a decrease in Ψ<sub>π</sub>, hydrological flow between the soil and roots reaches equilibrium and ceases to move resulting in leaf loss and mortality. The points closest to zero on the x-axis are controls, and salinity treatments increase as they move to the right (more negative Ψ<sub>π</sub>) noted by the green-to-red gradient arrow. (<b>b</b>) The relationship between osmotic potential (Ψ<sub>π</sub>) of the groundwater treatment solutions (NaCl) and the difference between midday water potential (Ψ<sub>md</sub>) and Ψ<sub>pd</sub> across all species and salinity treatments. As Ψ<sub>π</sub> increases (salinity treatments become more saline), hydrological flow between the soil (Ψ<sub>pd</sub>) and light-adapted leaves (Ψ<sub>md</sub>) reach equilibrium (Ψ<sub>md</sub> − Ψ<sub>pd</sub> = 0; noted by “No H<sub>2</sub>O Transport”). Equilibrium is expected at high soil salinity meaning water would cease to move to more negative pressure potential in the leaves.</p> Full article ">Figure 6
<p>Reflectance spectra from <span class="html-italic">Acer rubrum</span> leaves in October 2018 for select salinity treatments (control = dark green, 1 ppt = light green, 3 ppt = yellow, 4 ppt = orange, 6 ppt = red) showing the wavelengths expected to correlate with salinity and drought stress (531, 570, 680, and 800 nanometers). Photochemical reflectance index (PRI) is derived from narrowband reflectance at 531 and 570 nanometers (nm), and normalized difference vegetation index (NDVI) derived from red and near-infrared calculated as NDVI = (NIR − Red)/(NIR + Red), which is reflected over the incoming radiation. Here, we used the reflectance values at 680 (red) and 800 nm (infrared) to calculated NDVI. An NDVI close to 0–0.1 corresponds to no vegetation, while NDVI close to 0.8–0.9, as seen here in the control treatment (NDVI = 0.827), indicates the highest possible density of green leaves.</p> Full article ">Figure A1
<p>Soil nutrients (NO<sub>3</sub><sup>−</sup>, NH<sub>4</sub><sup>+</sup>, and PO<sub>4</sub><sup>−</sup>) across binned intermediate salinity treatments. Non-replicated treatments were put into two groups, low (0.5, 1, and 2 ppt) and high (4, 5, and 6 ppt) salinity levels. Controls are green and become more orange with increase in salinity. Ammonium concentrations in soils are significantly greater at salinity ≥3 ppt. Bars are colored by control (dark green), low (light green), 3 ppt (tan), and high (orange) salinity treatments. Asterisks indicate statistically significant differences of salinity treatments to controls Asterisks indicate statistical significance (<span class="html-italic">p</span> ≤ 0.05).</p> Full article ">Figure A2
<p>(<b>a</b>) Total whole-plant leaf area (cm<sup>2</sup>) by species and binned treatments. Log transformed whole-plant leaf area of (<b>b</b>) <span class="html-italic">Acer rubrum</span> (<span class="html-italic">p</span> = 0.039) and (<b>c</b>) <span class="html-italic">Pinus taeda</span> (<span class="html-italic">p</span> = 0.046) along the soil sodium gradient. Non-replicated treatments were put into two groups, low (0.5, 1, and 2 ppt) and high (4, 5, and 6 ppt) salinity levels. Bars are colored by control (dark green), low (light green), 3 ppt (tan), and high (orange) salinity treatments. Asterisks indicate statistical significance (<span class="html-italic">p</span> ≤ 0.05).</p> Full article ">Figure A3
<p>(<b>a</b>,<b>b</b>) Cumulative leaf loss by species and (<b>c</b>) proportion of <span class="html-italic">Acer rubrum</span> litter fall over the course of this experiment compared to (<b>d</b>) groundwater-specific conductance (µs/cm). Non-replicated treatments were put into two groups, low (0.5, 1, and 2 ppt) and high (4, 5, and 6 ppt) salinity levels (<b>a</b>,<b>b</b>).</p> Full article ">Figure A3 Cont.
<p>(<b>a</b>,<b>b</b>) Cumulative leaf loss by species and (<b>c</b>) proportion of <span class="html-italic">Acer rubrum</span> litter fall over the course of this experiment compared to (<b>d</b>) groundwater-specific conductance (µs/cm). Non-replicated treatments were put into two groups, low (0.5, 1, and 2 ppt) and high (4, 5, and 6 ppt) salinity levels (<b>a</b>,<b>b</b>).</p> Full article ">Figure A4
<p>Comparison of (<b>a</b>) specific leaf area (SLA, leaf area cm<sup>3</sup>/g dry mass) and (<b>b</b>) leaf dry matter content (LDMC, mg dry leaf mass/g water-saturated fresh leaf mass) within and across all six species and binned salinity treatments (control, low, mid, and high). Non-replicated treatments were put into two groups, low (0.5, 1, and 2 ppt) and high (4, 5, and 6 ppt) salinity levels. Treatments statistically significant (<span class="html-italic">p</span> ≤ 0.05) compared to controls are indicated with an asterisk above the boxplot. Black asterisks below the boxplot indicator significance to other salinity treatment within the bracket. Letters below each set of boxplots per species indicate the statistical significance across species controls. Black points are outliers (values &gt; 1.5 times the interquartile range) included in the statistical analysis.</p> Full article ">Figure A5
<p>(<b>a</b>) The relationship between osmotic potential (Ψ<sub>π</sub>) of the groundwater treatment solutions (NaCl) after the second salinity dose and the difference between Ψ<sub>π</sub> and predawn leaf water potentials (Ψ<sub>pd</sub>) across the hardwood species and salinity treatments. Each color and shape combination represent Ψ<sub>π</sub> and Ψ<sub>pd</sub> for each species. The horizontal arrow (color gradient from green to red) represents the direction of salinity increase as Ψ<sub>π</sub> becomes more negative. The vertical arrow in panel (<b>a</b>) shows that as Ψ<sub>pd</sub> decreases in tandem with a decrease in Ψ<sub>π</sub>, hydrological flow between the soil and roots reaches equilibrium and ceases to move resulting in leaf loss and mortality. The points closest to zero on the x-axis are controls and salinity treatments increase as they move to the right (more negative Ψ<sub>π</sub>), noted by the green to red gradient arrow. (<b>b</b>) The relationship between osmotic potential (Ψ<sub>π</sub>) of the groundwater treatment solutions (NaCl) and the difference between midday water potential (Ψ<sub>md</sub>) and Ψ<sub>pd</sub> across the hardwood species and salinity treatments. As Ψ<sub>π</sub> increases (salinity treatments become more saline) hydrological flow between the soil (Ψ<sub>pd</sub>) and light-adapted leaves (Ψ<sub>md</sub>), equilibrium would be expected (Ψ<sub>md</sub> − Ψ<sub>pd</sub> = 0; noted by “No H<sub>2</sub>O Transport”) at high soil salinity, meaning water would ceases to move to more negative pressure potential in the leaves.</p> Full article ">Figure A6
<p>CO<sub>2</sub> assimilation, i.e., photosynthetic rate (A<sub>net</sub>, μmol CO<sub>2</sub> m<sup>−2</sup> s<sup>−1</sup>), for six tree species from June to October. Significant differences in salinity treatments mean (<span class="html-italic">p</span> ≤ 0.05) from the controls are marked with asterisks, and marginally significant means (<span class="html-italic">p =</span> 0.05–0.1) with hats just above the x-axis at zero, colored by the treatment. Green squares and orange diamonds are the primary replicated salinity treatments (control and 3 ppt, respectively). Non-replicated treatments were put into two groups, low (0.5, 1, and 2 ppt) and high (4, 5, and 6 ppt) salinity levels. Grey triangles and black circles are the low (0.5, 1, and 2 ppt) and high (4, 5, and 6 ppt) treatments. Measurements were taken every month ±5 days from the first day of each month. Points of each measurement are offset for ease of visualization, but all measurements for each species were taken in 1–2 days between 10:00–15:00 h.</p> Full article ">Figure A7
<p>Stomatal conductance (<span class="html-italic">g<sub>s</sub></span>, μmol H<sub>2</sub>O m<sup>−2</sup> s<sup>−1</sup>) for six tree species from June to October. Significant differences in salinity treatments mean (<span class="html-italic">p</span> ≤ 0.05) from the controls are marked with asterisks, and marginally significant means (<span class="html-italic">p =</span> 0.05–0.1) with hats just above the x-axis at zero, colored by the treatment. Green squares and orange diamonds are the primary replicated salinity treatments (control and 3 ppt, respectively). Non-replicated treatments were put into two groups, low (0.5, 1, and 2 ppt) and high (4, 5, and 6 ppt) salinity levels. Measurements were taken every month ±5 days from the first day of each month. Points of each measurement are offset for ease of visualization, but all measurements for each species were taken in 1–2 days between 10:00–15:00 h.</p> Full article ">Figure A8
<p>Quantum efficiency of photosystem II (ΦPSII) of light-adapted leaves all six tree species from June–October 2018 using a pulse-amplitude modulated (PAM) fluorometer chamber for measuring leaf chlorophyll fluorescence and gas exchange simultaneously. Marginal significance in each salinity treatment means (<span class="html-italic">p =</span> 0.05–0.1) from the controls are marked with hats just above the x-axis at zero, colored by the treatment significantly affected by salinity. Green squares and orange diamonds are the primary replicated salinity treatments (control and 3 ppt, respectively). Non-replicated treatments were put into two groups, low (0.5, 1, and 2 ppt) and high (4, 5, and 6 ppt) salinity levels. Measurements were taken every month roughly ±5 days from the first day of each month. Points of each measurement are offset for ease of visualization, but all measurements for each species were taken in 1–2 days between 10:00–15:00 h.</p> Full article ">Figure A9
<p>(<b>a</b>) Linear relationship (R<sup>2</sup> = 0.52, <span class="html-italic">p</span> = &lt;0.001) between stomatal conductance (g<sub>wv</sub>) and photosynthesis rate (A<sub>net</sub>) across all 6 species (<span class="html-italic">Acer rubrum</span>, <span class="html-italic">Juniper virginiana</span>, <span class="html-italic">Nyssa sylvatica</span>, <span class="html-italic">Pinus taeda</span>, <span class="html-italic">Quercus nigra</span>, and <span class="html-italic">Taxodium distichum</span>) and binned by salinity treatments (control, low (0.5–2 ppt), mid (3 ppt), and high (4–6 ppt)). Control trees are indicated by green circles, 0.5–2 ppt salinity by light green hollow circles, 3 ppt salinity by orange triangles, and 4–6 ppt by red hollow triangles. (<b>b</b>) Linear relationship (R<sup>2</sup> = 0.59, <span class="html-italic">p</span> = &lt;0.01) between stomatal conductance (g<sub>wv</sub>) and photosynthesis rate (A<sub>net</sub>) of <span class="html-italic">Acer rubrum</span> in the two replicated salinity treatments: controls (green circles) and 3 ppt (orange triangles).</p> Full article ">Figure A9 Cont.
<p>(<b>a</b>) Linear relationship (R<sup>2</sup> = 0.52, <span class="html-italic">p</span> = &lt;0.001) between stomatal conductance (g<sub>wv</sub>) and photosynthesis rate (A<sub>net</sub>) across all 6 species (<span class="html-italic">Acer rubrum</span>, <span class="html-italic">Juniper virginiana</span>, <span class="html-italic">Nyssa sylvatica</span>, <span class="html-italic">Pinus taeda</span>, <span class="html-italic">Quercus nigra</span>, and <span class="html-italic">Taxodium distichum</span>) and binned by salinity treatments (control, low (0.5–2 ppt), mid (3 ppt), and high (4–6 ppt)). Control trees are indicated by green circles, 0.5–2 ppt salinity by light green hollow circles, 3 ppt salinity by orange triangles, and 4–6 ppt by red hollow triangles. (<b>b</b>) Linear relationship (R<sup>2</sup> = 0.59, <span class="html-italic">p</span> = &lt;0.01) between stomatal conductance (g<sub>wv</sub>) and photosynthesis rate (A<sub>net</sub>) of <span class="html-italic">Acer rubrum</span> in the two replicated salinity treatments: controls (green circles) and 3 ppt (orange triangles).</p> Full article ">Figure A10
<p>Operating efficiency of photosystem II (Φ PSII) in light-adapted <span class="html-italic">Acer rubrum</span> leaves as a function of photochemical reflectance index (PRI) (<b>top row</b>) and normalized difference vegetation index (NDVI) (<b>bottom row</b>) in June, September, and October 2018. Each point is the mean of each of the eight salinity treatments, with horizontal and vertical error bars as standard errors (0.95 CI). Non-linear regression lines (dark grey) are significant relationship (October 2018).</p> Full article ">
16 pages, 5051 KiB  
Article
Aboveground Carbon Stocks across a Hydrological Gradient: Ghost Forests to Non-Tidal Freshwater Forested Wetlands
by Christopher J. Shipway, Jamie A. Duberstein, William H. Conner, Ken W. Krauss, Gregory B. Noe and Stefanie L. Whitmire
Forests 2024, 15(9), 1502; https://doi.org/10.3390/f15091502 - 28 Aug 2024
Viewed by 647
Abstract
Upper estuarine forested wetlands (UEFWs) play an important role in the sequestration of atmospheric carbon (C), which is facilitated by their position at the boundary of terrestrial and maritime environments but threatened by sea level rise. This study assessed the change in aboveground [...] Read more.
Upper estuarine forested wetlands (UEFWs) play an important role in the sequestration of atmospheric carbon (C), which is facilitated by their position at the boundary of terrestrial and maritime environments but threatened by sea level rise. This study assessed the change in aboveground C stocks along the estuarine–riverine hydrogeomorphic gradient spanning salt-impacted freshwater tidal forested wetlands to freshwater forested wetlands in seasonally tidal and nontidal landscape positions. Standing stocks of C in forested wetlands were measured along two major coastal river systems, the Winyah Bay in South Carolina and the Savannah River in Georgia (USA), replicating and expanding a previous study to allow the assessment of change over time. Aboveground C stocks on these systems averaged 172.9 Mg C ha−1, comparable to those found in UEFWs across the globe and distinct from the terrestrial forested ecosystems they are often considered to be a part of during large-scale C inventory efforts. Groundwater salinity conditions as low as 1.3 ppt were observed in conjunction with losses of aboveground C. When viewed in context alongside expected sea level rise and corresponding saltwater intrusion estimates, these data suggest a marked decrease in aboveground C stocks in forested wetlands situated in and around tidal estuaries. Full article
(This article belongs to the Special Issue Coastal Forest Dynamics and Coastline Erosion, 2nd Edition)
►▼ Show Figures

Figure 1

Figure 1
<p>Site locations within the southeastern Atlantic coast of the United States, including the Savannah River, Georgia, and Winyah Bay, South Carolina.</p> Full article ">Figure 2
<p>Water level patterns vary across the estuarine gradient of the systems, being characterized as either low-frequency, high-magnitude (<b>left</b>), or semidiurnal (<b>right</b>) flood patterns. Note that the two hydrographs show different temporal scales on the x-axes, but the same meter scale on the y-axes, and retain the same color designation for each river throughout.</p> Full article ">Figure 3
<p>Observed total aboveground carbon (Mg C ha<sup>−1</sup>) by estuary position of every individual plot.</p> Full article ">Figure 4
<p>(<b>Top</b>) Tree carbon (C) in Megagrams per hectare by river position. (<b>Bottom</b>) Percent contribution of each biomass pool to the given plot’s total C, barring live mature trees.</p> Full article ">Figure 5
<p>The % change in aboveground tree carbon (C) between sampling years and the average salinity across the intervening years (<a href="#forests-15-01502-t005" class="html-table">Table 5</a>). This simple linear regression fails to fully account for the repeated measures data structure and should be interpreted with caution, but provides a preliminary value of an approximately 26% loss in tree C per 1 ppt.</p> Full article ">
21 pages, 4944 KiB  
Article
Tidal Freshwater Forested Wetlands in the Mobile-Tensaw River Delta along the Northern Gulf of Mexico
by Andrew Balder, Christopher J. Anderson and Nedret Billor
Forests 2024, 15(8), 1359; https://doi.org/10.3390/f15081359 - 3 Aug 2024
Viewed by 1084
Abstract
Tidal freshwater forested wetlands (TFFWs) typically occur at the interface between upriver non-tidal forests and downstream tidal marshes. Due to their location, these forests are susceptible to estuarine and riverine influences, notably periodic saltwater intrusion events. The Mobile-Tensaw (MT) River Delta, one of [...] Read more.
Tidal freshwater forested wetlands (TFFWs) typically occur at the interface between upriver non-tidal forests and downstream tidal marshes. Due to their location, these forests are susceptible to estuarine and riverine influences, notably periodic saltwater intrusion events. The Mobile-Tensaw (MT) River Delta, one of the largest river deltas in the United States, features TFFWs that are understudied but threatened by sea level rise and human impacts. We surveyed 47 TFFW stands across a tidal gradient previously determined using nine stations to collect continuous water level and salinity data. Forest data were collected from 400 m2 circular plots of canopy and midstory species composition, canopy tree diameter and basal area, stem density, and tree condition. Multivariate hierarchical clustering identified five distinct canopy communities (p = 0.001): Mixed Forest, Swamp Tupelo, Water Tupelo, Bald Cypress, and Bald Cypress and Mixed Tupelo. Environmental factors, such as river distance (p = 0.001) and plot elevation (p = 0.06), were related to community composition. Similar to other TFFWs along the northern Gulf of Mexico, forests closest to Mobile Bay exhibited lower basal areas, species density, diversity, and a higher proportion of visually stressed individual canopy trees compared to those in the upper tidal reach. Results indicate a strong tidal influence on forest composition, structure, and community-level responses. Full article
(This article belongs to the Special Issue Coastal Forest Dynamics and Coastline Erosion, 2nd Edition)
►▼ Show Figures

Figure 1

Figure 1
<p>The lower Mobile-Tensaw River Delta study site with completed forest surveys, water monitoring station locations, and the watershed, where the black-lined outline denotes the study site.</p> Full article ">Figure 2
<p>Dendrogram from Hellinger transformed canopy tree data with a Bray–Curtis distance matrix and Flexible linkage (β = −0.25), analyzed with 12 species/groupings from 43 forest plots. Groupings are defined by different colored lines, with the pruning height being the dashed black line.</p> Full article ">Figure 3
<p>Graphical representation of indicator species analysis for each cluster, ranging from 2 to 10 clusters (x-axis). An indicator value was used for all 12 species/groups against cluster level, where the subsequent p-values were extracted from the Monte Carlo simulations and their values summed (z-axis) along with the number of significant indicator species, <span class="html-italic">p</span> &lt; 0.05 (y-axis). The vertical dashed red line at k = 5 indicates the final pruning point.</p> Full article ">Figure 4
<p>Plot-level species IV<sub>200</sub> for all clustered forest plots. Bars represent the cumulative percentage IV<sub>200</sub> of all species in each plot. The bottom number represents forest type based on clustering: (1) Mixed Forest, (2) Swamp Tupelo, (3) Water Tupelo, (4) Bald Cypress, and (5) Bald Cypress and Mixed Tupelo.</p> Full article ">Figure 5
<p>NMDS ordination of plots separated by cluster in two dimensions. Significant (&lt;0.05) environmental vector overlay indicates the relationship of elevation in meters and river distance to plot ordination. Circles indicate tidal grouping.</p> Full article ">Figure 6
<p>Spatial orientation of cluster-based forest types and long-term water monitoring stations.</p> Full article ">Figure 7
<p>Ghosts forest of the MT River Delta, composed of standing dead <span class="html-italic">T. distichum</span> trees throughout a <span class="html-italic">Cladium jamaicense</span> marsh, located at the downstream extent of the Bayou Sara Tributary.</p> Full article ">
16 pages, 3080 KiB  
Article
Interactive Effects of Salinity and Hydrology on Radial Growth of Bald Cypress (Taxodium distichum (L.) Rich.) in Coastal Louisiana, USA
by Richard H. Day, Andrew S. From, Darren J. Johnson and Ken W. Krauss
Forests 2024, 15(7), 1258; https://doi.org/10.3390/f15071258 - 19 Jul 2024
Cited by 1 | Viewed by 755
Abstract
Tidal freshwater forests are usually located at or above the level of mean high water. Some Louisiana coastal forests are below mean high water, especially bald cypress (Taxodium distichum (L.) Rich.) forests because flooding has increased due to the combined effects of [...] Read more.
Tidal freshwater forests are usually located at or above the level of mean high water. Some Louisiana coastal forests are below mean high water, especially bald cypress (Taxodium distichum (L.) Rich.) forests because flooding has increased due to the combined effects of global sea level rise and local subsidence. In addition, constructed channels from the coast inland act as conduits for saltwater. As a result, saltwater intrusion affects the productivity of Louisiana’s coastal bald cypress forests. To study the long-term effects of hydrology and salinity on the health of these systems, we fitted dendrometer bands on selected trees to record basal area increment as a measure of growth in permanent forest productivity plots established within six bald cypress stands. Three stands were in freshwater sites with low salinity rooting zone groundwater (0.1–1.3 ppt), while the other three had higher salinity rooting zone groundwater (0.2–4.9 ppt). Water level was logged continuously, and salinity was measured monthly to quarterly on the surface and in groundwater wells. Higher groundwater salinity levels were related to decreased bald cypress radial growth, while higher freshwater flooding increased radial growth. With these data, coastal managers can model rates of bald cypress forest change as a function of salinity and flooding. Full article
(This article belongs to the Special Issue Coastal Forest Dynamics and Coastline Erosion, 2nd Edition)
►▼ Show Figures

Figure 1

Figure 1
<p>Location map of six study sites in Louisiana, USA. BT = Bayou Teche, MA = Mandalay, BC = Bayou Chevrieul, TI = Treasure Island, JL = Jean Lafitte, and FL = Fleming. Circles = freshwater sites. Triangles = saltwater sites. Top inset of USA states: TX = Texas, LA = Louisiana, MS = Mississippi, AL = Alabama, and FL = Florida. Map source: USGS National Hydrography Dataset. Available at <a href="https://www.usgs.gov/national-hydrography/national-hydrography-dataset" target="_blank">https://www.usgs.gov/national-hydrography/national-hydrography-dataset</a> (accessed 15 April 2023).</p> Full article ">Figure 2
<p>(<b>a</b>) 31-day hydrographs recorded by water level pressure sondes with hourly water levels of six study sites during the month of July 2010, (<b>b</b>) direction and velocity of wind (Meteorological station WBAN:53915 New Iberia, LA, USA) during maximum sustained wind speed for the day (e.g., an arrow pointing straight up represents wind coming directly from the south). The circle highlights strong sustained winds &gt; 10 km/h for two days from the southeast, which resulted in high water levels at all sites depicted in <a href="#forests-15-01258-f002" class="html-fig">Figure 2</a>a. BT = Bayou Teche, JL = Jean Lafitte, BC = Bayou Chevrieul, MA = Mandalay, TI = Treasure Island, and FL = Fleming.</p> Full article ">Figure 3
<p>Salinity measured during the period 2008–2016: summary statistics showing mode (rectangles) plus maximum and minimum values (vertical bars) at six study sites in Louisiana. TI = Treasure Island, FL = Fleming, MA = Mandalay, BC = Bayou Chevrieul, BT = Bayou Teche, and JL = Jean Lafitte.</p> Full article ">Figure 4
<p>Flooding, salinity, and tree growth for six study sites in Louisiana (<b>a</b>) 9-year mean annual individual tree basal area increment (BAI) ± 1 SE, letters above the bars represent significant difference between sites from a 2-way ANOVA with dependent variable annual BAI and independent variable Site, (<b>b</b>) 9-year mean salinity ± 1 SE, (<b>c</b>) total percent time flooded above tree base. TI = Treasure Island, FL = Fleming, MA = Mandalay, BC = Bayou Chevrieul, BT = Bayou Teche, and JL = Jean Lafitte.</p> Full article ">Figure 5
<p>Annual means for six study sites in Louisiana (Salt = 3 sites, Fresh = 3 sites) (<b>a</b>) individual tree basal area increment (BAI) ± 1 SE (Salt = 60 bald cypress trees, Fresh = 44 bald cypress trees), letters above the bars represent significant differences between years for the combined Salt and Fresh pairings from a 2-way ANOVA with dependent variable annual BAI and independent variable Year, (<b>b</b>) salinity; (<b>c</b>) percent flooded.</p> Full article ">Figure 6
<p>9-year mean daily individual tree basal area increment (BAI) ± 1 SE. Salt = 3 sites and 60 bald cypress trees. Fresh = 3 sites and 44 bald cypress trees.</p> Full article ">Figure 7
<p>Relationships for (<b>a</b>) salinity (ppt ± 1 SE) and (<b>b</b>) percent flooded with mean annual basal area increment (BAI, cm<sup>2</sup>/yr ± 1 SE) of bald cypress trees (Salt = 60 trees, Fresh = 44 trees) at six study sites in Louisiana (Salt = 3 sites, Fresh = 3 sites). Each point equals annual means for three sites combined.</p> Full article ">Figure 8
<p>Relationship for percent flooded with salinity (ppt ± 1 SE) at six study sites in Louisiana (Salt = 3 sites, Fresh = 3 sites) over 9 years. Each point equals annual means for three sites combined.</p> Full article ">
15 pages, 2706 KiB  
Article
Coastal Forest Change and Shoreline Erosion across a Salinity Gradient in a Micro-Tidal Estuary System
by Lori E. Gorczynski, A. Reuben Wilson, Ben K. Odhiambo and Matthew C. Ricker
Forests 2024, 15(6), 1069; https://doi.org/10.3390/f15061069 - 20 Jun 2024
Viewed by 874
Abstract
Coastal Zone Soil Survey mapping provides interpretive information that can be used to increase coastal resiliency and quantify how coastal ecosystems are changing over time. North Carolina has approximately 400,500 ha of land within 500 m of the tidal coastline that is expected [...] Read more.
Coastal Zone Soil Survey mapping provides interpretive information that can be used to increase coastal resiliency and quantify how coastal ecosystems are changing over time. North Carolina has approximately 400,500 ha of land within 500 m of the tidal coastline that is expected to undergo some degree of salinization in the next century. This study examined 33 tidal wetlands in the Albemarle–Pamlico Sound along a salinity gradient to provide a coastal zone mapping framework to quantify shoreline change rates. The primary ecosystems evaluated include intact tidal forested wetlands (average water salinity, 0.15–1.61 ppt), degraded “ghost forest” wetlands (3.51–8.28 ppt), and established mesohaline marshes (11.73–15.47 ppt). The average shoreline rate of change (m/yr) was significantly different among estuary ecosystems (p = 0.004), soil type (organic or mineral) (p < 0.001), and shore fetch category (open or protected) (p < 0.001). From 1984 to 2020, a total of 2833 ha of land has been submerged due to sea level rise in the Albemarle–Pamlico Sound with the majority (91.6%) of this loss coming from tidal marsh and ghost forest ecosystems. The results from this study highlight the importance of maintaining healthy coastal forests, which have higher net accretion rates compared to other estuarine ecosystems. Full article
(This article belongs to the Special Issue Coastal Forest Dynamics and Coastline Erosion, 2nd Edition)
►▼ Show Figures

Figure 1

Figure 1
<p>Map of the 33 map units where shoreline change rates were calculated (field site labels correspond to <a href="#forests-15-01069-t001" class="html-table">Table 1</a>) with wind stations and weighted wind fetch in meters. Prevailing winds come from the southwest or northeast, aligning with the long axis of the Pamlico Sound generating a large fetch. Fetch decreases in the Albemarle Sound and up the microtidal rivers.</p> Full article ">Figure 2
<p>Graph showing hectares inundated in North Carolina of different soil orders for 0.30 and 0.91 m of sea level rise scenarios [<a href="#B3-forests-15-01069" class="html-bibr">3</a>,<a href="#B28-forests-15-01069" class="html-bibr">28</a>].</p> Full article ">Figure 3
<p>Linear regression (red line) between shoreline change rates and fetch for the 33 soil map units selected. Gray lines represent 95% confidence interval. Positive values represent net accretion versus negative values that represent net shoreline erosion. Outlier data points with the greatest net erosion rates are from Point Peter, which is a low-elevation tidal marsh that has been anthropogenically modified via ditching which contributes to increased shoreline erosion in this area [<a href="#B10-forests-15-01069" class="html-bibr">10</a>].</p> Full article ">Figure 4
<p>Graph showing average rate of shoreline change in the three ecosystems and fetch categories with standard error bars. Different letters indicate significant differences (α = 0.05).</p> Full article ">Figure 5
<p>Graph showing average rate of shoreline change for the three ecosystems and soil types with standard error bars. Typic are deep organic soils (≥130 cm peat depth) and Terric are shallow organic soils (40–130 cm peat depth). Different letters indicate significant differences (α = 0.05).</p> Full article ">Figure 6
<p>Graph showing total hectares submerged in the APES from 1984 to 2020 by ecosystem type.</p> Full article ">
19 pages, 7068 KiB  
Article
Multivariate Analysis of the Community Composition of Tidal Freshwater Forests on the Altamaha River, Georgia
by Galen Costomiris, Christine M. Hladik and Christopher Craft
Forests 2024, 15(1), 200; https://doi.org/10.3390/f15010200 - 19 Jan 2024
Cited by 1 | Viewed by 1221
Abstract
Situated in the transitional zone between non-tidal forests upstream and tidal freshwater marshes downstream, tidal freshwater forests (TFF) occupy a unique and increasingly precarious habitat due to the threat of saltwater intrusion and sea level rise. Salinization causes tree mortality and forest-to-marsh transition, [...] Read more.
Situated in the transitional zone between non-tidal forests upstream and tidal freshwater marshes downstream, tidal freshwater forests (TFF) occupy a unique and increasingly precarious habitat due to the threat of saltwater intrusion and sea level rise. Salinization causes tree mortality and forest-to-marsh transition, which reduces biodiversity and carbon sequestration. The Altamaha River is the longest undammed river on the United States East Coast and has extensive TFF, but there have been only limited field studies examining TFF along the entire gradient of salinity and flooding. We surveyed thirty-eight forest plots on the Altamaha River along a gradient of tidal influence, and measured tree species composition, diameter, and height. Hierarchical clustering and indicator species analysis were used to identify TFF communities. The relationship of these communities to elevation and river distance was assessed using non-metric multidimensional scaling (NMDS). We identified six significantly different forest communities: Oak/Hornbeam, Water Tupelo, Bald Cypress/Tupelo, Pine, Swamp Tupelo, and Bald Cypress. Both elevation and river distance were significantly correlated with plot species composition (p = 0.001). Plots at the downstream extent of our study area had lower stem density, basal area, and species diversity than those further upstream, suggesting saltwater intrusion. This study demonstrates the importance of and need for thorough and robust analyses of tidal freshwater forest composition to improve prediction of TFF response to sea level rise. Full article
(This article belongs to the Special Issue Coastal Forest Dynamics and Coastline Erosion, 2nd Edition)
►▼ Show Figures

Figure 1

Figure 1
<p>Study area (delineated in black) with plot locations on the Altamaha River, Georgia. Plot locations (red stars) are overlaid on the National Wetland Inventory (NWI) map of the area. The red diamond marks the location of the salinity and water depth sensors at Georgia Coastal Ecosystems Long-Term Ecological Research (GCE LTER) site 11.</p> Full article ">Figure 2
<p>Plot-level species importance values (IV) for 37 sampling locations on the Altamaha River, GA. Bars represent the cumulative IV of all species in each plot. For clarity, only the eight species with the highest total IV across all plots are shown.</p> Full article ">Figure 3
<p>Dendrogram produced via hierarchical clustering using Hellinger distance and Ward linkage for 16 tree species from 37 plots in the Altamaha TFF. Plot names are listed on the right and community names are given for each of the six groups.</p> Full article ">Figure 4
<p>Summary of results of indicator species analyses. Hierarchical clustering was used to group plots (<span class="html-italic">N</span> = 37) into 2–10 clusters. For each clustering level, an indicator value index (IVI) was calculated for each species. <span class="html-italic">p</span>-values were derived from 1000 Monte Carlo simulations with randomized data, then totaled for all species at each grouping level (<span class="html-italic">x</span> axis). The final pruning level of six clusters was selected to maximize the number of significant indicator species and minimize total <span class="html-italic">p</span> while giving reasonable ecological interpretation.</p> Full article ">Figure 5
<p>NMDS ordination of plots in species space. A two-dimensional solution was optimal. Shaded polygons indicate the communities identified through hierarchical clustering. Biplot overlays indicate the relationship of elevation in meters above NAVD88 and longitude (as a proxy for river distance) to plot ordination. Both elevation (r<sup>2</sup> = 0.645) and longitude (r<sup>2</sup> = 0.545) were significantly correlated with both axes (<span class="html-italic">p</span> = 0.001).</p> Full article ">Figure 6
<p>Distribution of plot elevation in meters (<b>A</b>) and longitude (a proxy for distance from river mouth in km) (<b>B</b>) for each of our six tidal freshwater forest communities. Plots are represented by colored points. Black circles are the mean for each community, and vertical bars show the standard error. Dunn’s test for multiple comparisons indicated that the only significant differences in elevation were between the Bald Cypress and Water Oak/Hornbeam Communities (<span class="html-italic">p</span> = 0.026) and Swamp Tupelo and Water Oak/Hornbeam Communities (<span class="html-italic">p</span> = 0.027). Differences in distance from river mouth were only significant for Bald Cypress and Water Oak/Hornbeam (<span class="html-italic">p</span> = 0.001) and Swamp Tupelo and Water Oak/Hornbeam Communities (<span class="html-italic">p</span> = 0.008).</p> Full article ">Figure 7
<p>Distribution of tidal freshwater forest communities identified via hierarchical clustering. Plots 331 and 350 were excluded from analyses based on outlier analysis.</p> Full article ">Figure 8
<p>Comparison of healthy and salt-stressed tidal forest canopy and understory vegetation for the bald cypress community (<b>A</b>,<b>B</b>) and swamp tupelo community (<b>C</b>,<b>D</b>). Healthy plots are on the left; salt-stressed plots are on the right. Plots shown are 326 (<b>A</b>), 346 (<b>D</b>), 345 (<b>C</b>), and 347 (<b>B</b>).</p> Full article ">
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-6
Back to TopTop