Freshwater Forest Research Articles

Novel water sources restore plant and animal communities along an urban river

AbstractMany projects have been undertaken to restore urban rivers in arid regions. At the same time, passive discharge of urban water sources has stimulated redevelopment of wetlands and riparian forests along stretches of dewatered rivers. In Phoenix, Arizona, for example, some segments of the dewatered Salt River have been actively restored by planting and irrigation, whereas others have revegetated in response to runoff from storm drains and effluent drains. Our research documents how biotic communities differ between these actively restored and ‘accidentally’ restored areas, and between wetter and drier urban reaches. We addressed these objectives with a multi‐taxa, multi‐season sampling approach along reaches of the Salt River. We quantified plants using cover estimates in quadrats, birds using fixed radius, point‐count surveys, and herpetofauna (amphibians and reptiles) using visual‐encounter surveys. One notable finding was that wetland plants had greater richness and cover at accidentally restored sites compared with actively restored, dry urban, and non‐urban reference sites. Birds and herpetofauna, however, were most species‐rich at actively restored and non‐urban reference sites, and riparian birds were more abundant at sites with perennial flows compared with ephemeral reaches. From a landscape perspective, the range of management approaches along the river (including laissez‐faire) is sustaining a diverse riparian and wetland mosaic. Urban water subsidies are sustaining freshwater forests and marshlands, the latter a regionally declining ecosystem. In urbanized rivers of arid regions, mapping and conserving perennial stream flows arising from stormwater and effluent discharge can be an important complement to active restoration. Copyright © 2014 John Wiley & Sons, Ltd.

Variation in the Flora and Fauna of Tidal Freshwater Forest Ecosystems Along the Columbia River Estuary Gradient: Controlling Factors in the Context of River Flow Regulation

Tidal freshwater forested wetlands are dynamic, complex ecosystems that typically occur in large, floodplain river estuaries throughout the world. The estuarine portion of the Columbia River, in the Pacific Northwest region of North America, is exceptionally large and extends from the Pacific Ocean to the head of tide at Bonneville Dam, located at river kilometer (RKm) 233. Our study focused on the freshwater portion of the estuarine gradient (RKm 40 to RKm 233) of the Columbia River estuary and the corresponding continuum of hydrologic regimes and biotic communities. Several diverse forested wetland community types occurred along this freshwater estuarine gradient with major shifts in community composition corresponding to the transition from predominantly tidal to predominantly fluvial hydrologic regimes. We quantitatively characterized the floristic structure, species composition, and species richness of these tidal wetlands. Additionally, we documented variation in the avifaunal and insect assemblages associated with the floral structure. We found that freshwater tidal forested wetlands in the lower reaches of the estuary were characterized by high vegetation species richness and complex forest and scrub-shrub ecosystems, while tidal wetlands in the upper reaches of the estuary displayed a greater diversity of wetland ecosystems (forested, scrub-shrub, emergent, and aquatic bed) but comparatively lower species richness. A transitional area in the mid-estuary contained forested wetlands that exhibited some similarities to estuarine forested wetlands in both the upper and lower reaches. Likewise, avifauna and insect assemblage composition transitioned along the tidal freshwater estuarine gradient. Differences in geomorphological and hydrological regimes along the estuarine gradient appear to be the factors controlling the variation in tidal freshwater forested wetland characteristics and species composition. A thorough understanding of this complex and understudied system is necessary for predicting the potential impacts of hydrologic regime alterations and climate change and for guiding ongoing restoration efforts in the region.

Soil Phosphorus Dynamics and Saltwater Intrusion in a Florida Estuary

Soils in riparian wetlands are thought to stifle eutrophication in coastal water bodies by entraining and transforming nutrients. Altered hydrology and sea level rise underscore the need to evaluate the role of salinity in nutrient cycling within these settings. We studied three intertidal wetlands along the St. Johns River estuary, Florida in order to relate soil phosphorus composition with the distribution of saltwater. Sites represented a tidal freshwater forest, a brackish marsh, and a saltmarsh. Total phosphorus and organic composition decreased along the axis of the estuary as ambient salinity increased. At upstream wetlands, porewater revealed an inverse correlation between PO4 3− and the presence of saltwater (Cl− and SO4 2−) suggesting soil efflux. During experiments, aerobic soils did not liberate PO4 3− when exposed to seawater. During anaerobic experiments, SO4 2− amended soils from a saltmarsh mobilized substantial amounts of PO4 3− but the same effect was not observed in low-salinity wetland soils. Results indicate that P availability is shaped by saltwater access in the estuary and that SO4 2− reduction may regenerate PO4 3− in the saltmarsh. We suggest this is relevant to the St. John’s river in light of ongoing eutrophication and planned surfacewater withdrawals, which may draw saline water farther upstream.

Time Capsule in the Desert

Deep beneath western China's Qaidam Basin are traces of gigantic freshwater lakes and lush forests that gave way to steppe and desert tens of millions of years ago.

Sediment Accretion in Tidal Freshwater Forests and Oligohaline Marshes of the Waccamaw and Savannah Rivers, USA

Sediment accretion was measured at four sites in varying stages of forest-to-marsh succession along a fresh-to-oligohaline gradient on the Waccamaw River and its tributary Turkey Creek (Coastal Plain watersheds, South Carolina) and the Savannah River (Piedmont watershed, South Carolina and Georgia). Sites included tidal freshwater forests, moderately salt-impacted forests at the freshwater–oligohaline transition, highly salt-impacted forests, and oligohaline marshes. Sediment accretion was measured by use of feldspar marker pads for 2.5 year; accessory information on wetland inundation, canopy litterfall, herbaceous production, and soil characteristics were also collected. Sediment accretion ranged from 4.5 mm year−1 at moderately salt-impacted forest on the Savannah River to 19.1 mm year−1 at its relict, highly salt-impacted forest downstream. Oligohaline marsh sediment accretion was 1.5–2.5 times greater than in tidal freshwater forests. Overall, there was no significant difference in accretion rate between rivers with contrasting sediment loads. Accretion was significantly higher in hollows than on hummocks in tidal freshwater forests. Organic sediment accretion was similar to autochthonous litter production at all sites, but inorganic sediment constituted the majority of accretion at both marshes and the Savannah River highly salt-impacted forest. A strong correlation between inorganic sediment accumulation and autochthonous litter production indicated a positive feedback between herbaceous plant production and allochthonous sediment deposition. The similarity in rates of sediment accretion and sea level rise in tidal freshwater forests indicates that these habitats may become permanently inundated if the rate of sea level rise increases.

Neogene–Quaternary sedimentary and paleovegetation history of the eastern Solimões Basin, central Amazon region

Palynological and stratigraphical analyses were carried out on the outcrops of the Solimões River to present new information about freshwater paleoenvironments of a fluvial–deltaic and meandering river system, evaluate the vegetation changes in the upper Solimões and Içá Formations in the eastern Solimões Basin, and the role of the Purus Arc in the evolution of central Amazon during the upper Neogene. The upper Miocene to Pliocene Solimões Formation is related to a fluvial–deltaic system, with fine-grained sediments of the prodelta–lacustrine environment supplied by meandering distributaries and delta front environment. The lake and distributaries were surrounded by extensive deltaic and floodplains colonized by lowland freshwater forests under wet climate conditions, persisting until the Pliocene. The Içá Formation started to deposit unconformably on the Solimões Formation during the Pleistocene, following the development of extensive meandering channels surrounded by floodplains of an essentially fluvial system linked to development of the present eastward direction of the Amazon River until the Atlantic coast. These floodplains were colonized by few palm species and pteridophytes of lowland freshwater forests during the Pleistocene. Additionally, no algae and fungi were observed, which may be related to drier climate conditions and/or different morphological conditions than the upper Solimões Formation.

Tidal freshwater forest accretion does not keep pace with sea level rise

AbstractSoil properties, accretion, and accumulation were measured in tidal freshwater forests (tidal forests) of the Ogeechee, Altamaha, and Satilla rivers of the South Atlantic (Georgia USA) coast to characterize carbon (C) sequestration and nutrient (nitrogen‐N, phosphorus‐P) accumulation in these understudied, uncommon, and ecologically sensitive wetlands. Carbon sequestration and N and P accumulation also were measured in a tidal forest (South Newport River) that experiences saltwater intrusion to evaluate the effects of sea level rise (SLR) and saltwater intrusion on C, N and P accumulation. Finally, soil accretion and accumulation of tidal forests were compared with tidal fresh, brackish and salt marsh vegetation downstream to gauge how tidal forests may respond to SLR. Soil accretion determined using 137C and 210Pb averaged 1.3 and 2.2 mm yr−1, respectively, and was substantially lower than the recent rate of SLR along the Georgia coast (3.0 mm yr−1). Healthy tidal forest soils sequestered C (49–82 g m−2 yr−1), accumulated N (3.2–5.3 g m−2 yr−1) and P (0.29–0.56 g m−2 yr−1) and trapped mineral sediment (340–650 g m−2 yr−1). There was no difference in long‐term accretion, C sequestration, and nutrient accumulation between healthy tidal forests and tidal forests of the South Newport River that experience saltwater intrusion. Accelerated SLR is likely to lead to decline of tidal forests and expansion of oligohaline and brackish marshes where soil accretion exceeds the current rate of SLR. Conversion of tidal forest to marshes will lead to an increase in the delivery of some ecosystem services such as C sequestration and sediment trapping, but at the expense of other services (e.g. denitrification, migratory songbird habitat). As sea level rises in response to global warming, tidal forests and their delivery of ecosystem services face a tenuous future unless they can migrate upriver, and that is unlikely in most areas because of topographic constraints and increasing urbanization of the coastal zone.

Characterization of Methanotrophic Communities in Soils from Regions with Different Environmental Settings

Methanotrophic communities from freshwater wetland (FW), seawater wetland (SW), forest (FS), and landfillsoils (LS) around Seoul of South Korea, were characterized using comparative sequence analyses of clonelibraries. Proportions of Methylocaldum, Methlyococcus and Methylosinus were found to be greater in FW andSW, while Methylobacter and Methylomonas were more notable in FS and Methylocystis and Methylomicro-bium more prominent in LS. Lag periods behind the initiation of methane oxidation significantly variedamongst the soils. Methane oxidation rates were greater in FW≥LS≥SW>FS (p<0.05). Thus, the environmen-tal setting is a significant factor influencing the communities and capabilities of methanotrophs.Keywords: Methanotrophs, clone library, environmental setting, methane oxidation potentialThere are diverse methanotrophs in natural environmentswhere they utilize methane as their sole source of carbonand energy. Environmental characteristics such as climatic,physiographic, geologic, biotic, and land-use features candetermine growth and activity of methanotrophs. For instance,methane concentration is a key determinant for methanotro-phic community composition as well as characteristics ofmethane oxidation [6, 9, 11, 13]. Methanotrophs in well-aerated upland soils show a high enzymatic affinity formethane since they grow on atmospheric methane [1, 9]. Incontrast, methanotrophs in wetland or landfill soils mayhave lower enzymatic affinity levels since they grow onmethane produced in the soils or emitted from the landfills,respectively. The main objective in the present study was totest hypotheses that environmental setting can determinewhether a specific type of methanotrophs is present, andthat it also can determine methane-oxidation potential ofmethanotrophs.We defined methanotrophic communities and characterizedCH

Periodicity in Stem Growth and Litterfall in Tidal Freshwater Forested Wetlands: Influence of Salinity and Drought on Nitrogen Recycling

Many tidally influenced freshwater forested wetlands (tidal swamps) along the south Atlantic coast of the USA are currently undergoing dieback and decline. Salinity often drives conversion of tidal swamps to marsh, especially under conditions of regional drought. During this change, alterations in nitrogen (N) uptake from dominant vegetation or timing of N recycling from the canopy during annual litter senescence may help to facilitate marsh encroachment by providing for greater bioavailable N with small increases in salinity. To monitor these changes along with shifts in stand productivity, we established sites along two tidal swamp landscape transects on the lower reaches of the Waccamaw River (South Carolina) and Savannah River (Georgia) representing freshwater (≤0.1 psu), low oligohaline (1.1–1.6 psu), and high oligohaline (2.6–4.1 psu) stands; the latter stands have active marsh encroachment. Aboveground tree productivity was monitored on all sites through monthly litterfall collection and dendrometer band measurements from 2005 to 2009. Litterfall samples were pooled by season and analyzed for total N and carbon (C). On average between the two rivers, freshwater, low oligohaline, and high oligohaline tidal swamps returned 8,126, 3,831, and 1,471 mg N m−2 year−1, respectively, to the forest floor through litterfall, with differences related to total litterfall volume rather than foliar N concentrations. High oligohaline sites were most inconsistent in patterns of foliar N concentrations and N loading from the canopy. Leaf N content generally decreased and foliar C/N generally increased with salinization (excepting one site), with all sites being fairly inefficient in resorbing N from leaves prior to senescence. Stands with higher salinity also had greater flood frequency and duration, lower basal area increments, lower tree densities, higher numbers of dead or dying trees, and much reduced leaf litter fall (103 vs. 624 g m−2 year−1) over the five study years. Our data suggest that alternative processes, such as the rate of decomposition and potential for N mineralization, on tidal swamp sites undergoing salinity-induced state change may be more important for controlling N biogeochemical cycling in soils than differences among sites in N loading via litterfall.

Effects of Salinity on Denitrification and Greenhouse Gas Production from Laboratory-incubated Tidal Forest Soils

We measured ambient and potential denitrification in tidal freshwater floodplain forest (tidal forests) soils along the Altamaha, Ogeechee, and Satilla Rivers in southeast Georgia to characterize nitrogen removal from these understudied systems. Further, we measured the response of denitrification, greenhouse gas production (CO2, CH4, N2O), and the formation of reduced inorganic sulfur species following laboratory incubations simulating saltwater intrusion with salinity levels of 2 and 5. Ambient denitrification ranged from 0.03 μg N2O/g/hr in the Satilla River to 0.40 μg N2O/g/hr in the Altamaha River. Potential denitrification was two to eight times greater than ambient denitrification. Denitrification from Satilla River soils increased with salinity, while Altamaha and Ogeechee River soils were unaffected. Methane production, however, was inhibited by salinity, decreasing by 77% in the 2 treatment and 89% in the 5 treatment whereas CO2 generally increased with salinity, though exhibited a variable response between the three rivers. Formation of reduced sulfur species followed a similar trend to CO2 production. Our findings suggest that tidal forests are effective sinks for N, capable of producing anywhere from 0.032 to 1.9 μg N2O/g soil/hr. Overall, salinity increased the amount of C mineralized suggesting that low levels of salinity can alter the short-term C dynamics of tidal freshwater forests.

Sapflow and water use of freshwater wetland trees exposed to saltwater incursion in a tidally influenced South Carolina watershed

Sea-level rise and anthropogenic activity promote salinity incursion into many tidal freshwater forested wetlands. Interestingly, individual trees can persist for decades after salt impact. To understand why, we documented sapflow (Js), reduction in Jswith sapwood depth, and water use (F) of baldcypress ( Taxodium distichum (L.) Rich.) trees undergoing exposure to salinity. The mean Jsof individual trees was reduced by 2.8 g H2O·m–2·s–1(or by 18%) in the outer sapwood on a saline site versus a freshwater site; however, the smallest trees, present only on the saline site, also registered the lowest Js. Hence, tree size significantly influenced the overall site effect on Js. Trees undergoing perennial exposure to salt used greater relative amounts of water in outer sapwood than in inner sapwood depths, which identifies a potentially different strategy for baldcypress trees coping with saline site conditions over decades. Overall, individual trees used 100 kg H2O·day–1on a site that remained relatively fresh versus 23.9 kg H2O·day–1on the saline site. We surmise that perennial salinization of coastal freshwater forests forces shifts in individual-tree osmotic balance and water-use strategy to extend survival time on suboptimal sites, which further influences growth and morphology.

Predicting the retreat and migration of tidal forests along the northern Gulf of Mexico under sea-level rise

Tidal freshwater forests in coastal regions of the southeastern United States are undergoing dieback and retreat from increasing tidal inundation and saltwater intrusion attributed to climate variability and sea-level rise. In many areas, tidal saltwater forests (mangroves) contrastingly are expanding landward in subtropical coastal reaches succeeding freshwater marsh and forest zones. Hydrological characteristics of these low-relief coastal forests in intertidal settings are dictated by the influence of tidal and freshwater forcing. In this paper, we describe the application of the Sea Level Over Proportional Elevation (SLOPE) model to predict coastal forest retreat and migration from projected sea-level rise based on a proxy relationship of saltmarsh/mangrove area and tidal range. The SLOPE model assumes that the sum area of saltmarsh/mangrove habitat along any given coastal reach is determined by the slope of the landform and vertical tide forcing. Model results indicated that saltmarsh and mangrove migration from sea-level rise will vary by county and watershed but greater in western Gulf States than in the eastern Gulf States where millions of hectares of coastal forest will be displaced over the next century with a near meter rise in relative sea level alone. Substantial losses of coastal forests will also occur in the eastern Gulf but mangrove forests in subtropical zones of Florida are expected to replace retreating freshwater forest and affect regional biodiversity. Accelerated global eustacy from climate change will compound the degree of predicted retreat and migration of coastal forests with expected implications for ecosystem management of State and Federal lands in the absence of adaptive coastal management.

Research Insight from Tidal Freshwater Forested Wetlands

Research Insight from Tidal Freshwater Forested Wetlands

Primary production, nutrient dynamics, and accretion of a coastal freshwater forested wetland assimilation system in Louisiana

This study reports on the response of a tidal, freshwater forested wetland ecosystem to long-term input of secondarily treated municipal effluent from the City of Mandeville, LA. Measurements of hydrology, nutrients, and aboveground net primary productivity were made from September 1998 through March 2002. Accretion measurements were made in October 2000 and October 2004. The major hydrologic inputs to the system were the effluent, precipitation, and back water flooding from Lake Pontchartrain. Nutrient levels were generally low except in the immediate vicinity of the outfall. Mean net primary production of the freshwater forest system was significantly higher downstream of the effluent discharge (1202 g m −2 yr −1) compared to the control site (799 g m −2 yr −1). Downstream of the outfall, accretion rates were double the rate of relative sea level rise in the area. Removal efficiencies of N and P were as high as 75% and 95%, respectively. The relatively constant flow of secondarily treated municipal effluent buffered the downstream area from salinity intrusion during a region-wide drought. Re-direction of nutrient-enhanced effluents from open water bodies to wetland ecosystems can maintain plant productivity, sequester carbon, and maintain coastal wetland elevations in response to sea-level rise in addition to improving overall surface water quality, reducing energy use, and increasing financial savings.

Transient Uplift After a 17th-Century Earthquake Along the Kuril Subduction Zone

In eastern Hokkaido, 60 to 80 kilometers above a subducting oceanic plate, tidal mudflats changed into freshwater forests during the first decades after a 17th-century tsunami. The mudflats gradually rose by a meter, as judged from fossil diatom assemblages. Both the tsunami and the ensuing uplift exceeded any in the region's 200 years of written history, and both resulted from a shallow plate-boundary earthquake of unusually large size along the Kuril subduction zone. This earthquake probably induced more creep farther down the plate boundary than did any of the region's historical events.

Coastally restricted forests

1. Introduction: Freshwater forests of continental margins: overview and synthesis Part I. Chamaecyparis (False-cypress) Studies 2. Chamaecyparis forests: a comparative analysis Pacific Rim 3. Reproduction and forest decline of Chamaecyparis nootkatensis (yellow cedar) in southeast Alaska, USA 4. Problems and research needs for Chamaecyparis nootkatensis forest management in coastal British Columbia, Canada 5. Genecology of Chamaecyparis nootkatensis 6. Managing Chamaecyparis Lawsoniana (ort Orford cedar) to control the root disease caused by Phytophthora lateralis in the Pacific Northwest, USA 7. Regeneration ecology of Chamaecyparis obtusa and C. Pisifera (Hinoki and Sawara cypress), Japan Atlantic Coast, North America 8. Chamaecyparis thyoides (Atlantic white cedar) in the United States: extent and characterization using broad-scale inventory data 9. Reconstruction of the Mashantucket Pequot cedar swamp paleoenvironment using plant using plant macrofossils, New England, USA 10. Plant community structure in Chamaecyparis Thyoides swamps in the New Jersey Pinelands Biosphere Reserve, USA 11. Atlantic white cedar in North Carolina, USA: a brief history and current regeneration effots 12. Population genetic analysis of Chamaecyparis thyoides in New Hampshire and Maine, USA Part II. Systems with Diverse Dominants, Systems not dominated by Chamaecyparis species 13. Characteristics of the soil and water table in an Alnus japonica (Japanese alder) 14. Pinus pumila (Siberian dwarf pine) on the Kamchatka Peninsula, northeast Asia: ecology of seed production 15. The Sequoia sempervirens (coast redwood) forest of the Pacific coast, USA 16. Distribution and ecology of low freshwater coastal forests of the Yucatan Peninsula, Mexico 17. Taxodium-Nyssa (cypress-tupelo) forest along the coast of southern United States 18. Impact of hurricanes on forests of the Atlantic and Gulf Coasts, USA 19. The effect of sea level rise on coastal wetland forests: the Mississippi Delta, USA, as a model 20. Root aeration in wetland trees and its ecophysiological significance Part III: Management and Research 21. Coastal forest management and reseach

Depostional [sic] Environments of the Rock Springs Formation, Southwest Flank of the Rock Springs Uplift, Wyoming

A record at an ancient delta system Is preserved in outcrops along the flanks of the Rock Springs Uplift, southwestern Wyoming. The deltaic Upper Cretaceous Rock Springs Formation of the Mesaverde Group was deposited during early Campanian time near the end of the regressive phase of the Niobrara cyclothem. On the southwest end of the Uplift, part of the delta system is exposed near the seaward edge of a series of transgressive/regressive sequences, which consist of intertonguing prodelta, delta-front, and delta-plain deposits. Eight major delta-front sandstones are vertically stacked and laterally continuous throughout the main study area, intertonguing with prodefta deposits of the Blair Formation and Black Butte and Coulson Shale Tongues bf the Rock Springs Formation. Delta-front sandstones consist mainly of interdistributary shoreface deposits composed of sand redistributed from point sources by longshore currents. Preservation of distributary-channel and mouth-bar deposits is rare due to intense wave reworking. The shorelines were modified by large-scale storm events. Distributary-channel, crevasse-splay, overbank, crevasse-subdelta, interdistributary-bay, marsh, swamp, flood-tidal delta, and washover deposits accumulated behind delta-front sandstones, mostly in lower delta-plain environments. In this lower delta-plain setting, peat was deposited in freshwater forest swamps as isolated pods and linear belts behind delta-front sands. The resulting coal beds are thin, pinching and splitting to the southeast of the study area. In contrast, in more landward settings north of the study area, non-marine sequences contain thicker and more continuous coal beds that accumulated in the lower parts of upper delta-plain environments.

Macrophytes: Freshwater Forests of Lakes and Rivers

Karla J. McDermid is a graduate student and NSF Fellow in the botany department at the University of Hawaii, Honolulu 96822. She received both her B.S. degree in biology and B.A. degree in Spanish from Stanford University. This paper is an offshoot of research done while she studied in the MIT/Woods Hole Oceanographic Institution Joint Graduate Program. McDermid's own doctoral work focuses on marine algal ecology, especially plant-plant interactions. She has also participated in research projects tracking sperm whales in the West Indies, collecting macrozooplankton 2000 feet deep from a submersible, and SCUBA diving for chitons in California kelp beds. Robert J. Naiman is an associate scientist at Woods Hole Oceanographic Institution, Woods Hole, MA 02543. He is also director of the Matamek Research Station in Quebec. He received his B.S. degree from California Polytechnic University, an M.S. degree from UCLA, and his Ph.D. in zoology from Arizona State University. Naiman's research interests include stream ecology and ecosystem analyses. At present he is investigating watershed dynamics of northern boreal forest streams and rivers, and relationships between fish and their food supply. Naiman is co-editor of Fishes in North American Deserts and has written numerous articles published in professional journals. Let them think twice before they use their powers To blot out and drink up and sweep away These flowery waters and these water flowers... from Spring Pools by Robert Frost