Swamp Tupelo Research Articles

Tidal Freshwater Forested Wetlands in the Mobile-Tensaw River Delta along the Northern Gulf of Mexico

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.

Multivariate Analysis of the Community Composition of Tidal Freshwater Forests on the Altamaha River, Georgia

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.

Foliar water uptake of fog confers ecophysiological benefits to four common tree species of southeastern freshwater forested wetlands

AbstractFog, dew and cloud‐borne mist are sources of water to vegetation in many ecosystems. The importance of fog as a water source has been documented well beyond ecosystems where plants experience fog for extensive periods over the course of the day (e.g. cloud forests); however, relatively little is known regarding the roles of fog and foliar water uptake in ecosystems such as coastal freshwater wetlands that do not experience fog for extensive periods over the course of the day. Coastal freshwater wetland ecosystems lie on the forefront of climate change‐associated stressors that threaten freshwater supplies to vegetation. Considering the potential impact of climate warming on diminishing coastal fog regimes, an improved understanding of the ecophysiological benefits of fog immersion to the vegetation in these ecosystems is critical for understanding the response of these ecosystems to global climate change. Herein, we investigate the potential for foliar water deposition from fog to act as a direct freshwater subsidy to four tree species (Taxodium distichum (L.) Rich., Nyssa aquatica L., Nyssa biflora Walter and Liquidambar styraciflua L.) that are common in coastal freshwater wetlands. All four species showed the capacity for foliar water uptake across the leaf/needle surface, with a ca. 5–10% increase in leaf water content after a 3‐h submersion experiment. Stable isotopes of water provided strong evidence for foliar water uptake in all four species and for bark water uptake in T. distichum after a 24‐h fogging experiment. Fog exposure also resulted in several ecophysiological benefits to the saplings, including significant improvements in pre‐dawn water status and net photosynthesis.

Small gradients in salinity have large effects on stand water use in freshwater wetland forests

Salinity intrusion is responsible for changes to freshwater wetland watersheds globally, but little is known about how wetland water budgets might be influenced by small increments in salinity. We studied a forested wetland in South Carolina, USA, and installed sap flow probes on 72 trees/shrubs along a salinity gradient. Species investigated included the trees baldcypress (Taxodium distichum [L.] Rich.), water tupelo (Nyssa aquatica L.), swamp tupelo (Nyssa biflora Walt.), and the shrub waxmyrtle (Morella cerifera (L.) Small). This study improves upon past reliance on greenhouse seedling studies by adding measurements of trees/shrubs along a salinity gradient, and better describes the role of low salinity on water use in freshwater wetland forests. We measured patterns of water use related to salinity, atmospheric conditions and season, and hypothesized that salinity would influence wetland forest water use through two mechanisms: salinity disturbances would yield stands with species and size classes that transpire less and individual trees with less conductive xylem tissue (i.e., sapwood). Both hypotheses held. At salinity concentrations ranging from fresh to 3 psu, forest structural changes alone resulted in stand water use reductions from 494 mm year-1 in freshwater stands to 316 mm year-1 in stands of slightly higher salinity. Tree sapwood function (inferred from radial sap flux profiles) also changed along this gradient and reduced sap flow rates by an additional 13.3% per unit increase in salinity (psu). Thus, stand water use was further reduced to 190 mm year-1 on saline sites. We found that forest structure is not the only change that affects water use in salinized watersheds; individual tree eco-physiological responses to salinity, manifesting in different radial sap flow profiles, are important as well.

Tidal freshwater forests: Sentinels for climate change

We measured plant community composition and productivity, soil accretion, and C, N, and P burial in a tidal freshwater forest of the Altamaha River, Georgia to gain a better understanding of the ecosystem services they deliver and their ability to keep pace with current and future rates of sea level rise. Ten species were identified in two 0.1 ha plots. Nyssa aquatica (Tupelo Gum) made up 50% of the density and 57% of the total basal area. Nyssa biflora, Liquidambar styraciflua, and Fraxinus pennsylvanica were the next dominant species, collectively accounting for 37% of the density and 26% of the total basal area. Taxodium distichum only accounted for 3% of the density, but 12% of the total basal area. Aboveground productivity, measured as litterfall and stem wood growth, averaged 927 and 1030 g/m2 in 2015 and 2016, respectively, with litterfall accounting for 60% of the total. Tidal forest soils in the streamside and the interior (0–60 cm) contained 3–6% organic C, 0.20–0.40% N, and 270–540 µg/g P. Soil accretion based on 137Cs was 4.0 mm/year on the streamside and 0.2 mm/year in the forest interior. The rate of accretion in the interior is considerably less than the current rate of sea level rise (3.1 mm/year) along the Georgia coast. Because the accretion rate was much higher on the streamside, rates of C sequestration, N and P accumulation, and mineral sediment deposition also were much greater. Low accretion rates in the interior of the forest that accounts for most of the acreage suggests that accelerated sea level rise is likely to lead to foreseeable death of tidal forests from saltwater intrusion and submergence.

Pretreatment Effects on Seed Germination of Two Nyssa Species

The genus Nyssa L. includes several woody species with traits valued by horticulturists, but only black gum (Nyssa sylvatica Marsh.) is prevalent in the nursery trade. A congener, swamp tupelo (Nyssa biflora Walt.), might be a marketable shade tree, but little is known about propagating it from seeds. Because cold, moist stratification overcomes embryo dormancies of black gum, we compared germination of cleaned seeds (surrounding pulp of fruits removed) of swamp tupelo and black gum that were stratified at 5 °C for 0, 14, 28, 42, 56, 70, 84, and 112 days. Seeds of swamp tupelo within intact drupes were also stratified. Across all durations of stratification, 79% of cleaned seeds of swamp tupelo germinated, whereas 11% of seeds within drupes germinated. Germination value of cleaned seeds of swamp tupelo increased from 1.26 to 3.23 as duration of stratification increased. Although cleaned seeds of black gum responded similarly, the benefit of stratification was more pronounced, and the mean germination percentage was lower than for swamp tupelo (66% vs. 79%). In a second experiment, irrigation with low and high concentrations of an extract of fruit pulp of swamp tupelo reduced germination of seeds of basil (Ocimum basilicum L. ‘Superbo’), spinach (Spinacea oleracea L. ‘Bloomsdale’), zinnia (Zinnia ×marylandica Spooner, Stimart, and Boyle ‘Double Zahara Cherry’), and swamp tupelo by 25% to 63% (low concentration) and 40% to 70% (high concentration). Propagators should remove the surrounding pulp from seeds of swamp tupelo and cold stratify them at least for 4 weeks.

Description and Classification ofLindera melissifoliaHabitat in the Southeastern Coastal Plain

ABSTRACT Lindera melissifolia is a federally endangered wetland shrub endemic to the Southeastern Coastal Plain and the Lower Mississippi Alluvial Valley. Lindera melissifolia is known to occupy seasonally flooded habitats, but little work has been done to describe habitat characteristics in the Southeastern Coastal Plain region. This research uses vegetation and environmental data collected from 50 plots in North Carolina, South Carolina, and Georgia to develop a habitat classification and description for L. melissifolia in the Southeastern Coastal Plain. Cluster analysis, nonmetric multidimensional scaling, indicator species analysis, and analysis of variance were used to assign plots to four distinct isolated wetland habitat types. Swamp Tupelo Depression Pond and Successional Swamp Forest communities supported the densest and healthiest L. melissifolia populations, followed by Pond-Cypress Pond and Pocosin, and Limestone Sink Forest habitats. Habitat degradation and other forms of disturbance were fou...

Woody vegetation communities of tidal freshwater swamps in South Carolina, Georgia and Florida (US) with comparisons to similar systems in the US and South America

AbstractQuestionsWhat are the general tree communities found in tidal freshwater swamps along four large coastal rivers in the southeastern United States (US)? How do these communities compare to other tidal freshwater swamps in the US and South America?LocationsTidal floodplains of major rivers along the Atlantic and Gulf coasts of the southeastern US: Savannah, Altamaha, Suwannee and Apalachicola Rivers.MethodsAn extensive survey of trees and shrubs was conducted to describe the communities from a range of tidal freshwater swamps. River basins studied include micro‐tidal (Gulf coast) and meso‐tidal (Atlantic coast) regimes, and study areas were located both near and distant to primary channels. A total of 128 plots (100 m2 each) were inventoried, distributed evenly over the Savannah and Altamaha Rivers along the Atlantic coast, and the Suwannee and Apalachicola Rivers along the Gulf coast. Multivariate statistics helped discern communities and the significant indicator species in each.ResultsFour general communities were characterized and named according to the strongest individual indicator species in each: Water Tupelo (Nyssa aquatica) Community, Swamp Tupelo (Nyssa biflora) Community, Dwarf Palmetto (Sabal minor) Community and Cabbage Palm (Sabal palmetto) Community.ConclusionsDescriptions of most tidal freshwater swamps in the southeastern US fit within the communities described in this study. Because studies that make inferences between environmental drivers (e.g. salinity, hydroperiod, hurricanes) and specific community types are best applied to the same communities (but perhaps different river systems), this work provides a framework by which tidal freshwater forested wetlands can be accurately compared based on their tree communities. We suggest that, within the broad range of our inventories, the four communities described identify the primary associations that should be tracked within most tidal freshwater swamps of the US. However, we identify some river basins in the US that do not fit this construct. Diversity of major tree communities in tidal freshwater swamps outside the US is generally much lower (with the notable exception of Amazonian hardwood tidal várzea), as are basal area values.

Changing eastern broadleaf, southern mixed, and northern mixed forest ecosystems of the eastern United States

Recognition of changes in forests provides greater perspective about current trajectories of forests. I compared the newest USDA Forest Service Forest Inventory and Analysis (FIA) surveys to the oldest available surveys in the eastern United States to detect increasing and decreasing species and groups over large spatial extents. Species appeared to be increasing at the expense of decreasing species within each of the major forest ecosystems of the eastern United States. In eastern broadleaf forests, oaks and Virginia pine are decreasing and maples and eastern redcedar are increasing. In southern mixed forests, planted loblolly and slash pine are replacing shortleaf and longleaf pines, and longleaf pine wetland associates of swamp tupelo, pond cypress, and pond pine. In northern mixed forests of the Great Lake states, quaking aspen and paper birch are decreasing whereas red pine, later successional black spruce and northern white-cedar, and maples of eastern broadleaf forests are increasing. Indeed, red maple now is more frequent than aspen in northern mixed forests. The historical legacy of fire continues to affect forest composition. Without fire, fire-tolerant oaks and pines (that are not planted) still are decreasing, whereas fire-sensitive tree species are increasing. Forestry practices benefit planted pines but are not as effective at supporting quaking aspen against competition from red maple and species of the eastern broadleaf forest as in the past.

Stenanthium leimanthoides(Melanthiaceae) andNestronia umbellula(Santalaceae) in Alabama

Stenanthium leimanthoides (A. Gray) Zomlefer & Judd, commonly known as pine barren deathcamas, is classified in the Melanthiaceae family and is a former member of the polyphyletic genus Zigadenus (Zomlefer and Judd 2002). It is spottily distributed from New York and New Jersey south through West Virginia to North Carolina and Tennessee. It also appears in the Gulf Coastal Plain, where it is a rare taxon ranging from west central Georgia (Carter et al. 2009) to south Alabama, northwest Florida (Anderson 1995), south Mississippi, and southeast Louisiana, perhaps extending as far west as east Texas (USDA Plants Database 2012). Plants in the Gulf Coastal Plain are generally very robust, sometimes attaining heights of two meters or more. Flowering in the latter region is mostly from May through the middle of June, and plants typically have paniculate inflorescences in which each branch (raceme) is elongate and tight. Habitats of Stenanthium leimanthoides range from Atlantic white cedar and bay swamps in Georgia and Florida, to cutover shrub bogs and seepage slopes in other southeastern states, including Alabama. Pine barren deathcamas is listed as an S1 taxon by the Alabama Natural Heritage Program (2011) in Auburn. Species with this ranking are considered critically imperiled due to extreme rarity. While conducting fieldwork in late May of 2008 in the coastal plain of southeastern Alabama (frequently referred to as the Wiregrass Region), a new population of Stenanthium leimanthoides was discovered. Plants were at peak anthesis in southwestern Barbour County, Alabama (Figure 1). This site is approximately 95 km southeast of Montgomery and is in the Southern Red Hills physiographic region and the Choctawhatchee–Pea River Watershed. Pine barren deathcamas plants had paniculate inflorescences (Figure 2) and were robust, with heights of up to two meters. The habitat for the newly discovered population of S. leimanthoides is a seepage slope along a power line in a highway right-ofway cut through a creek swamp with Magnolia virginiana L., Liriodendron tulipifera L., Nyssa biflora Walter, and Persea palustris (Raf.) Sarg. A collection was made using standard herbarium techniques and was deposited in The University of Georgia Herbarium (GA) and the Troy University Herbarium (TROY). Table 1 has a listing of vascular plant species associated with S. leimanthoides at the Barbour County site. Nomenclature primarily follows Weakley (2011). Standardized abbreviations for authorities were obtained from The International Plant Names Index (2012). To learn more about the distribution and ecology of Stenanthium leimanthoides in Alabama, curators of the following herbaria were consulted: University of Alabama (UNA), Auburn University (AUA), Jacksonville State University (JSU), University of North Alabama (UNAF), University of South Alabama (USAM), Troy University (TROY), University of West Alabama, the Anniston Museum of Natural History, and Vanderbilt University (VDB) housed at the Botanical Research Institute of Texas (BRIT). Relevant specimens were directly examined at AUA, JSU, and TROY. The Alabama plant atlas (Kral et al. 2012) was accessed to verify the distribution of pine barren deathcamas in other regions of the state. Additional data on the distribution and habitats of this species were provided by the Alabama Natural Heritage Program in *email address: mwmorris@troy.edu Received June 8, 2011; Accepted September 11, 2012. DOI: 10.2179/12-016

Dissolved organic matter and nutrient dynamics of a coastal freshwater forested wetland in Winyah Bay, South Carolina

Seasonally flooded, freshwater cypress-tupelo wetlands, dominated by baldcypress (Taxodium distictum), water tupelo (Nyssaaquatica), and swamp tupelo (Nyssa sylvatica var. biflora) are commonly found in coastal regions of the southeastern United States. These wetlands are threatened due to climate change, sea level rise, and coastal urban development. Understanding the natural biogeochemical cycles of nutrients in these forested wetlands as ecosystems services such as carbon sequestration and nitrogen processing can provide important benchmarks to guide conservation plans and restoration goals. In this study, surface water and soil pore water samples were collected weekly from a cypress-tupelo wetland near Winyah Bay, South Carolina and analyzed for dissolved organic carbon (DOC), dissolved organic nitrogen (DON), inorganic nitrogen, and phosphate during its flooding period between October 2010 and May 2011. DOC was further characterized by specific ultra-violet absorbance at 254 nm, spectral slope ratio (SR) (ratio of two spectral slopes between 275–295 nm and 350–400 nm), E2/E3 ratio (ratio between A254 and A365), and fluorescence excitation-emission matrix. In addition, litterfall was collected on a monthly basis for a year while the biomass of the detritus layer (i.e., decomposed duff lying on the wetland floor) was determined before and after the flooding period. Results of the field study showed that concentrations of DOC, DON, NH4+–N, and (NO2− + NO3−)–N in the surface water were generally higher during the fall, or peak litterfall season (October to December), than in the spring season (March to May). Highest concentrations of 54.8, 1.48, 0.270, and 0.0205 mg L−1, for DOC, DON, NH4+–N, and (NO2− + NO3−)–N respectively, in surface waters were recorded during October. Lower SUVA, but higher SR and E2/E3 ratios of DOC, were observed at the end of the flooding season comparing to the initial flooding, suggesting the wetland system converts high aromatic and large DOC molecules into smaller and hydrophilic fractions possibly through photochemical oxidation. A similar trend was observed in soil pore water, but the pore water generally had greater and relatively stable concentrations of dissolved nutrients than surface water. No obvious temporal trend in phosphate concentration and total nitrogen to total phosphorus ratio (N:P) were found. Results of the laboratory extraction and mass balance calculation suggested fresh litter was a major source of DOC whereas decomposed duff was the source of dissolved nitrogen in surface water. In summary, the biogeochemistry of this isolated cypress-tupelo wetland is not only driven by the vegetation within the wetland system but also by hydrology and weather conditions such as groundwater table position, precipitation, and temperature.

Plant-Soil-Hydrology Relationships in Three Carolina Bays in Bladen County, North Carolina

Abstract This study provides quantitative ecological targets for restoring degraded peat-based Carolina Bays in the Carolina Flatwoods Ecoregion. Cluster analysis of vegetation data from three Carolina Bay reference sites in Bladen County, North Carolina, indicated four plant communities present: pond pine (Pinus serotina) woodland, non-riverine swamp forest dominated by swamp gum (Nyssa biflora), high pocosin dominated by evergreen shrubs with scattered pond pine, and bay forest dominated by loblolly bay (Gordonia lasianthus). We classified bay soils according to surface organic layer thickness (OLT) into mineral, histic, shallow organic, and deep organic types. We monitored the water table of each soil type in one bay throughout one growing season. The soil types with corresponding water table regimes were: mineral (9.4 cm mean OLT with a rooting zone water table [RZWT] 39% of the monitoring period), histic (27.5 cm OLT and 76% RZWT), shallow organic (63.9 cm OLT and 84% RZWT), and deep organic (102.5 c...

Cypress dome characteristics within one county of the Southern United States: a case study of changes

Cypress domes are non-transient, disconnected, depressional wetland areas scattered about the southern United States. Baldcypress (Taxodium distichum (L.) Rich.), swamp tupelo (Nyssa sylvatica var. biflora) and other trees species typically occupy these sites. Even though these areas are relatively fixed on the landscape, given land use changes over the last 60–70 years, the spatial character of the resource may have undergone some change as well. A small case study of one Georgia county suggests that there was net decrease in cypress dome land area from 1940 to 2007. The case study also suggests that there was a significant change in the land class(es) adjacent to or containing cypress domes. In addition, the physical shape of cypress domes seems to have changed, perhaps due to mechanical treatment of the land during commercial forestry operations. While the shape of cypress domes that were adjacent to mature forests in 1940 was not significantly different than the shape of the same cypress domes that were adjacent to mature forests in 2007, the shape of cypress domes adjacent to agricultural land and pasture/forest land uses in 1940 was significantly different in shape than their 2007 counterparts. Thus, the value of this study is in suggesting that the physical shape of cypress domes that were once adjacent to agricultural or pasture/forest lands seems to have changed, perhaps due to mechanical treatment of the land during the transition from agricultural practices to commercial forestry operations. The study also highlights the need for assessing the hydrologic changes in wetland function due to changes in cypress dome shape, and due to mechanical operations used along the edges of cypress domes to effectively adjust their shape. Research along these lines can lead to a better understanding of the spatial character of the cypress resource in areas that were once used for agricultural or pasture/forest purposes and may lead to more effective management strategies for protecting its role in society.

Emergence-Site Selection by the DragonflyEpitheca spinosa(Hagen)

Odonates are vulnerable during emergence, when they shed their larval skin (exuvia) to take flight as adults. Emergence-site selection should adapt to the local mortality risks. Here, I characterized emergence-site selection of Epitheca spinosa (Robust Baskettails) by noting the substrate, height, and distance from water of exuviae in a 300 m × 5 m plot at Weston Lake, Congaree National Park, Hopkins, SC. Of the 82 Robust Baskettail exuviae sampled, 52 (63.4%) were found on trees with corky bark (Nyssa aquatica [Water Tupelo], Nyssa biflora [Swamp Tupelo], Fraxinus pennsylvanica [Green Ash]), while no exuviae were found on the peeling, flaky trunks of Taxodium distichum (Bald Cypress) or the smooth, platy trunks of Acer rubrum (Red Maple). However, 26 (31.7%) exuviae were on T. distichum pneumatophores. This pattern was significantly different from the relative abundances of these substrate types (χ2 = 19.8, df = 3, P < 0.001). Most exuviae (93.9%) were on substrates touching the water, suggesting that larvae climb directly from the water to their emergence site. The mean height of exuviae on trees was 3.3 ± 1.37 m, with a range from 1.8–7.7 m. High-climbing by Robust Baskettail larvae may be an adaptation to flooding at Weston Lake; major flood events (>3 m) are common (5 of the last 10 years) during their March–April emergence period.

Vascular Flora of Sandhill Research and Education Center, Richland County, South Carolina

Abstract Sandhill Research and Education Center is located on 215 ha of greenspace in South Carolina. The Center is now surrounded by suburban development. Although located within the Sandhills region and within the historic range of the Longleaf Pine Forest, agriculture has been the predominant land use during the last century. With development pressure and an interest in transitioning from agriculture to ecological restoration, a baseline inventory of the flora was initiated to provide further guidance to administrators. This survey delineates six plant community types (Swamp Tupelo, Sand Hickory, Blackjack Oak, Turkey Oak, Field, and Utility Right-of-Way) and reports a total of 328 species in 237 genera and 100 families. It adds two state records (Lespedeza virgata and Lotus corniculatus), 38 county records, and several noteworthy species.

Cobalt uptake by Nyssa aquatica, N. sylvatica var. biflora, and Taxodium distichum seedlings

Cobalt is a minor contaminant in wetlands that has been linked to accumulation by Nyssa species for many years, though the evidence is largely anecdotal. We examined cobalt uptake characteristics from cobalt-enriched potting soil by Nyssa aquatica (water tupelo), N. sylvatica var. biflora (swamp tupelo), and Taxodium distichum (baldcypress), codominant canopy species of wetland forests of the southeastern United States. Seedlings were grown in 10 1 pots for two growing seasons. Cobalt additions (up to 100 mg/pot) did not affect biomass production of leaves, stems, or roots of the three species. Height was significantly different among treatments within a species, but no treatment was different from the control treatment with no added cobalt. Leaf cobalt concentrations were greater in N. sylvatica var. biflora than N. aquatica during the first year, but similar during the second year. Cobalt concentrations declined from the first to second years for T. distichum leaves. In the 100 mg/pot treatment, leaf cobalt concentrations of both Nyssa species during the second year were 150 times greater than that of T. distichum. Elevated cobalt uptake by Nyssa species is apparently a function of special mechanisms of the genera and not a habitat characteristic.

Decadal drought effects on endangered woodpecker habitat

The critically endangered ivory‐billed woodpecker (Campephilus principalis) apparently has been rediscovered in old‐growth bald cypress (Taxodium distichum, Figure 1) and swamp tupelo (Nyssa aquatica) forests of Bayou DeView, located seven kilometers northwest of Brinkley, Ark. [Fitzpatrick et al., 2005]. The evaluation of the impact of drought on forest history and wildlife population levels is critical to the conservation of the ivory‐billed woodpecker and other similarly endangered species. Tree ring chronologies have been developed from old‐growth forests at Bayou DeView to aid in this assessment.This article also describes a conceptual model that has proven useful for the discovery of other noncommercial old‐growth cypress‐tupelo remnants in the Southeast. These relict cypress‐tupelo stands may be candidates for conservation, restoration, and perhaps the eventual reintroduction of the ivory bill and other increasingly rare species native to this ecosystem.

Patterns of succession in forested depressional wetlands in north Florida, USA

Swamps dominated by the conifer Taxodium distichumvar. nutans (pondcypress) are believed to develop into swamps dominated by a variety of hardwood trees (primarily bays), where organic matter accumulates and fires do not occur. To determine the validity of this long-accepted pattern of succession, relationships among basin characteristics, tree composition, hydrology, soils, and logging history were ex- amined in nine pondcypress swamps and nine bay swamps in north central Florida. Basin depth was defined as the total of maximum standing water and organic matter depth. Shallow basins ( , 65 cm) contained pondcypress-pine (Pinus elliottii) communities; prolonged drought and fire may control the importance of pondcypress within these basins. Medium basins (65-150 cm) ranged in tree species composition from pure pondcypress communities to pondcypress-swamp tupelo (Nyssa sylvatica var. biflora ) communities to bay- cypress communities as organic matter depth increased and standing water depth decreased. Bay-cypress communities that had deeper organic matter than medium-basin pondcypress swamps also had low densities of large pondcypress trees and contained no pondcypress regeneration. Logging in medium-depth basins increased incidence of swamp tupelo and loblolly bay in pondcypress and bay swamps. Deep basins ( .150cm) were dominated by bay communities that did not contain pondcypress. Abundant advance regen- eration of loblolly bay (Gordonia lasianthus) suggests that this species eventually dominates undisturbed bay communities. Total basal area in pondcypress swamps was directly related to organic matter depth (r 2 5 0.53, p 5 0.016, n 5 9), suggesting that growth rate may also be related to this gradient. Productivity of pondcypress may be greatest in medium-basin pondcypress swamps, where deep organic matter leads to faster growth and deep standing water precludes the invasion of hardwoods. Pondcypress does not occur in deep basins. Basin geomorphology appears to play an important role in determining successional seres involving pondcypress and bay trees.

Root dynamics in bottomland hardwood forests of the Southeastern United States Coastal Plain

Effects of flooding on root dynamics appear nonlinear and therefore difficult to predict, leading to disparate and often contradictory reports of flooding impacts on production in bottomland hardwood forests. We explored root dynamics in two adjacent wetland habitats by comparing results obtained from several methods of estimating root processes. Also, we tested the influence of flooding on root dynamics of cherrybark, overcup, water and swamp chestnut oaks. Fine root biomass in the laurel oak habitat was greater ( α< 0.05) than in the swamp tupelo habitat (5.7 vs. 2.4 Mg ha −1 ), as was fine root necromass (2.4 vs. 1.3 Mg ha −1 ), productivity (2.3 vs. 0.3 Mg ha −1 yr −1 when the sum of significant increments method was used, 5.6 vs. 2.5 Mg ha −1 yr −1 when the maximum minus minimum method was used, and 1.2 vs. 1.0 Mg ha −1 yr −1 , when the root screen method was used), and turnover (40% and 12% per year). Mortality estimates were lower in the laurel oak habitat (1.3 and 1.2 Mg ha −1 yr −1 ) than in the swamp tupelo community (2.8 and 2.1 Mg ha −1 yr −1 ) when significant increment and maximum minus minimum methods were used, respectively. This apparent contradiction between estimates of production and mortality may be due to more rapid decomposition rates in the more aerated soil of the laurel oak than in the swamp tupelo forest type. Roots in the swamp tupelo habitat appeared to be longer-lived than in the laurel oak habitat. We concluded that there was greater investment in roots in the laurel oak habitat, where a shallow rooting zone and episodes of flooding and drought required drastic changes in root structure and physiology. In contrast, the swamp tupelo habitat had a deeper rooting zone and more consistently moist to flooded hydroperiod, allowing flood adapted roots to persist. The four oak species varied in their phenology of root production and response to flooding, from no difference among treatments for overcup oak to dramatic reductions in root growth during and after flooding for cherrybark oak. Flooding enhanced or at least did not negatively influence root growth in overcup oak, but seriously impacted root growth and survival of cherrybark oak and swamp chestnut oak. Different responses were attributed to the timing of root production: root growth began early for cherrybark oak so spring flooding severely affected this species. Growth in overcup oak began later and ended earlier than the other species tested, allowing the species a means of avoiding flood stress.

Vegetation, soil, and flooding relationships in a blackwater floodplain forest

Hydroperiod is considered the primary determinant of plant species distribution in temperate floodplain forests, but most studies have focused on alluvial (sediment-laden) river systems. Few studies have evaluated plant community relationships in blackwater river systems of the South Atlantic Coastal Plain of North America. In this study, we characterzied the soils, hydroperiod, and vegetation communities and evaluated relationships between the physical and chemical environment and plant community structure on the floodplain of the Coosawhatchie River, a blackwater river in South Carolina, USA. The soils were similar to previous descriptions of blackwater floodplain soils but had greater soil N and P availability, substantially greater clay content, and lower soil silt content than was previously reported for other blackwater river floodplains. Results of a cluster analysis showed there were five forest communities on the site, and both short-term (4 years) and long-term (50 years) flooding records documented a flooding gradient: water tupelo community > swamp tupelo > laurel oak = overcup oak > mixed oak. The long-term hydrologic record showed that the floodplain has flooded less frequently from 1994 to present than in previous decades. Detrended correspondence analysis of environmental and relative basal area values showed that 27% of the variation in overstory community structure could be explained by the first two axes; however, fitting the species distributions to the DCA axes using Gaussian regression explained 67% of the variation. Axes were correlated with elevation (flooding intensity) and soil characteristics related to rooting volume and cation nutrient availability. Our study suggests that flooding is the major factor affecting community structure, but soil characteristics also may be factors in community structure in blackwater systems.