Natural Forested Wetland Research Articles

Carbon storage and understory plant diversity in boreal Larix gmelinii–Carex schmidtii forested wetlands: A comparison of harvest, fire and draining disturbance

Background: Forested wetlands are an important factor in carbon (C) sequestration. In this study, we compared the short-term effects (5 years) of three harvest intensities and two wildfire severities, and the mid-term effects (25 years) of four groundwater table depth (WTD) drainage for forestry on eco-system C storage and understory vegetation structures in Daxing’anling, northeast of China. Results: We found that: Low intensity harvest slightly enhanced ecosystem C storage, whereas moderate- and high-intensity harvest led to significant reductions (33.2-41.6%) in comparison with the control natural forested wetlands stand (274.54 t C·ha -1), and light and heavy burn caused the ecosystem C storage sig-nificant decreases by 27.8% and 45.2%. As for the drainage for forestry, the ecosystem C storage was higher at the low WTD (316.78 t C·ha -1), and diminished significantly by 24.1-28.1% with the increasing WTD on the forested wetland plantation transect. Compared with the control and high intensity harvest stands (8.28 t ha -1 yr -1, 5.08 t C·ha -1 yr -1 and 6.48 t ha -1 yr -1, 3.52 t C·ha -1 yr -1), significantly higher NPP (net primary productivity, defined by the biomass difference of two measurements) (69.1-83.2%) and annual C sequestration (52.0-78.7%) were observed in the low- and moderate-intensity harvest stands. Significant increases by 48.6% and decreases by 31.5% in NPP or by 52.9% in annual C sequestration were in light and heavy burn stands, respectively. In contrast, the NPP and annual C sequestration (3. 67-10. 34 t ha -1 yr -1 and 1. 59-4. 87 t C·ha -1 yr -1) showed a significant in-creasing trend with increasing WTD, respectively. The understory species diversity indices were generally lower in the harvest and burned stands than the control natural forested wetlands and more pioneer tree species regeneration occurred after the disturbances. Conclusion: Therefore, it seems that low intensity harvest and wildfire could sustain the ecosystem C sink and drainage for forestry is an effect way to restore C sequestration for this forested wetland type.

Characterizing ambient nutrient concentrations and potential warning levels for surface water in natural forested wetlands in the Piedmont and Coastal Plain of North Carolina, USA

Nearly thirty years ago the U.S. EPA directed states to begin developing water quality standards specific to wetlands; however, progress has been limited. This study presents an overview of ambient wetland water quality and the first step towards the development of numeric nutrient standards for forested wetlands in North Carolina. Water quality samples were collected in 16 natural wetlands across the state for three years. The sites span a range of anthropogenic disturbance. The data was combined with historical data collected at these and other sites from 2005 to 2013. Concentration levels in wetlands without significant anthropogenic disturbance are likely higher than streams for TN, TP, similar for NH4+, and likely lower than streams for NO3–-N. A method developed by the U.S. EPA to establish reference levels was modified to define draft nutrient warning levels that may indicate anthropogenic impacts. These warning levels were calculated as 0.06 mg/L, 0.14 mg/L, 0.34 mg/L and 2.8 mg/L for NO3–-N, NH4+-N, TP and TN, respectively. NO3–-N and NH4+-N concentrations were the best indicators of disturbance. Overall, despite the limitations imposed by the sampling frequency and inherent variability in wetland ecosystems, this research methodology presents a reasonable first attempt at defining nutrient warning levels for undisturbed natural forested wetlands in N.C., and may serve as a starting point in developing numeric nutrient criteria for wetlands.

Characteristics and metabolic patterns of soil methanogenic archaea communities in the high-latitude natural forested wetlands of China.

Soil methanogenic microorganisms are one of the primary methane‐producing microbes in wetlands. However, we still poorly understand the community characteristic and metabolic patterns of these microorganisms according to vegetation type and seasonal changes. Therefore, to better elucidate the effects of the vegetation type and seasonal factors on the methanogenic community structure and metabolic patterns, we detected the characteristics of the soil methanogenic mcrA gene from three types of natural wetlands in different seasons in the Xiaoxing'an Mountain region, China. The results indicated that the distribution of Methanobacteriaceae (hydrogenotrophic methanogens) was higher in winter, while Methanosarcinaceae and Methanosaetaceae accounted for a higher proportion in summer. Hydrogenotrophic methanogenesis was the dominant trophic pattern in each wetland. The results of principal coordinate analysis and cluster analysis showed that the vegetation type considerably influenced the methanogenic community composition. The methanogenic community structure in the Betula platyphylla–Larix gmelinii wetland was relatively different from the structure of the other two wetland types. Indicator species analysis further demonstrated that the corresponding species of indicator operational taxonomic units from the Alnus sibirica wetland and the Betula ovalifolia wetland were similar. Network analysis showed that cooperative and competitive relationships exist both within and between the same or different trophic methanogens. The core methanogens with higher abundance in each wetland were conducive to the adaptation to environmental disturbances. This information is crucial for the assessment of metabolic patterns of soil methanogenic archaea and future fluxes in the wetlands of the Xiaoxing'an Mountain region given their vulnerability.

Metabolic diversity and seasonal variation of soil microbial communities in natural forested wetlands

This study explores the effects of vegetation and season on soil microorganisms and enzymatic activity of different wetlands in a temperate climate. Microbial carbon metabolism diversity was assessed using community-level physiological profiles (CLPP) with 31 different carbon substrates. CLPP indicated that significant interactions occur during carbon substrate metabolism of the microorganisms. Furthermore, the different types of vegetation present in the wetland ecosystem combined with the seasonal effects to influence microbial carbon metabolism and enzymatic activity. The most significant differences occurred to carbohydrates, carboxylic acids, and amino acids. The Mantel test confirmed positive correlations between soil enzymatic activities and microbial carbon metabolism. Soil microorganisms in Betula ovalifolia and Carex schmidtii wetlands used carbon substrates more efficiently in summer than those in other forested wetlands during other periods. Enzymatic activities also showed a similar trend as microbial carbon metabolism. The results demonstrate that microbial carbon metabolism patterns can be used as biological indicators in wetland ecological alterations due to vegetation type or to seasonal factors.

Effects of land-use change and drought on decadal evapotranspiration and water balance of natural and managed forested wetlands along the southeastern US lower coastal plain

Forested wetlands are important in regulating regional hydrology and climate. However, long-term studies on the hydrologic impacts of converting natural forested wetlands to pine plantations are rare for the southern US. From 2005-2018, we quantified water cycling in two post-harvest and newly-planted loblolly pine (Pinus taeda) plantations (YP2–7, 2–7 yrs old; YP2–8, 2–8 yrs old), a rotation-age loblolly pine plantation (MP, 15–28 yrs old), and a natural bottomland hardwood forest (BHF, > 100 yrs old) along the lower coastal plain of North Carolina. We quantified the differences in inter-annual and seasonal water balance and trends of evapotranspiration (ET) using eddy covariance over 37 site-years and assessed key climatic and biological drivers of ET. We found that the rotation-age plantation (MP) had higher annual ET (933 ± 63 mm) than the younger plantations (776 ± 74 mm for YP2–7 and 638 ± 190 mm for YP2–8), and the BHF (743 ± 172 mm), owing to differences in stand age, canopy cover, and micrometeorology. Chronosequence analysis of the pine sites showed that ET increased with stand age up to 10 years, then gradually stabilized for the remainder of the rotation of 28 – 30 years. YP2–8 was sensitive to water availability, decreasing ET by 30 – 43 % during the extreme 2007 – 2008 drought, but reductions in ET at MP were only 8 – 11 %. Comparing to BHF, ditching with management enhanced drainage at YP2–7 and YP2–8, while drainage was lower at the mature pine site. This study provides insight into land use-hydrology-climate interactions that have important implications for forested wetland management in a time of rapidly changing environmental conditions of the LCP of the southern US.

Long-term carbon flux and balance in managed and natural coastal forested wetlands of the Southeastern USA

Wetlands store large carbon (C) stocks and play important roles in biogeochemical C cycling. However, the effects of environmental and anthropogenic pressures on C dynamics in lower coastal plain forested wetlands in the southern U.S. are not well understood. We established four eddy flux stations in two post-harvest and newly-planted loblolly pine plantations (YP2–6, 2–6 yrs old; YP2–8, 2–8 yrs old), a rotation-aged loblolly pine plantations (MP, 15–27 yrs old), and a mixed bottomland hardwood forest (BHF, >100 yrs old) in the lower coastal plain of North Carolina, USA. We analyzed the gross primary productivity (GPP), ecosystem respiration (RE) and net ecosystem exchange (NEE) for age-related trends, interannual variability in response to climate forcing, and management-related disturbances from 2005 – 2017. For the first few years after being harvested, pine plantations were net C sources (NEE = 1133 and 897 g C m–2 yr–1 in YP2–6 and YP2–8, respectively). The MP was a strong C sink (–369 to –1131 g C m–2 yr–1) over the entire study period. In contrast, BHF was a C source (NEE = 87 g C m–2 yr–1 to 759 g C m–2 yr–1) in most years, although in the first year it did show a net C uptake (NEE = –368 g C m–2 yr–1). The source activity of BHF may have been related to increasing overstory tree mortality and diameter growth suppression. Decreases in relative extractable water in pine plantations enhanced GPP and RE. Pine plantations regained status as C sinks 5–8 years after harvest and recovered C equivalent to post-harvest losses at 8–14 years. Thus, coastal pine plantations have a net C uptake for only about half the 25-year rotation period, suggesting that they have decreased climate mitigation potential in comparison to protecting primary forests. However, primary forests in this area may be vulnerable to ecosystem transition, and subsequent C loss, due to the changing environmental conditions at the land-ocean interface.

小兴安岭天然森林沼泽湿地生态系统碳源/汇

PDF HTML阅读 XML下载 导出引用 引用提醒 小兴安岭天然森林沼泽湿地生态系统碳源/汇 DOI: 10.5846/stxb201601250174 作者: 作者单位: 东北林业大学生态研究中心,东北林业大学生态研究中心,东北林业大学生态研究中心,东北林业大学生态研究中心,东北林业大学生态研究中心 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31370461） Carbon source or sink of natural forested wetland ecosystem in Xiaoxing'anling region of China Author: Affiliation: Center for Ecological Research，Northeast Forestry University,Center for Ecological Research，Northeast Forestry University,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:采用静态箱-气相色谱法与相对生长方程法，同步测定小兴安岭7种天然沼泽湿地（草丛沼泽-C、灌丛沼泽-G、毛赤杨沼泽-M、白桦沼泽-B、落叶松苔草沼泽-L-T、落叶松藓类沼泽-L-X、落叶松泥炭藓沼泽-L-N）的土壤呼吸（CO2、CH4）净碳排放量、植被年净固碳量，并依据生态系统净碳收支平衡，揭示温带天然沼泽湿地的碳源/汇作用规律。结果表明：①7种天然沼泽CH4年通量（0.006-7.756 mg m-2 h-1）呈M（高于其他类型1.0-1291.7倍，P < 0.05）> C、G、B（高于针叶林沼泽17.7-649.0倍，P >0.05）> 针叶林沼泽变化趋势，其季节动态存在3种类型（C、G单峰型、M、B多峰型及针叶林沼泽排放与吸收交替型）；②其CO2年通量（157.40-231.06 mg m-2 h-1）呈G（高于森林沼泽28.7%-46.8%，P < 0.05）> C（高于森林沼泽7.4%-22.5%，P > 0.05）> 森林沼泽的变化趋势，其季节动态存在2种类型（C、G、L-X和L-N双峰型和M、B、L-T单峰型）；③C、G、M、B、L-N CH4排放仅受0-40 cm不同土壤层温度所控制；7种天然沼泽土壤CO2排放均受气温及0-40 cm不同土壤层温度所控制，但B、L-X、L-N受温度与水位综合控制；④其植被年净固碳量（（2.05±0.09）-（6.75±0.27）tC hm-2 a-1）呈C（高于其他类型65.4%-229.3%，P < 0.05）> G、B、L-T、L-X、L-N（高于M 80.0%-99.0%，P < 0.05）> M变化趋势；⑤7种天然沼泽的碳源/汇（-2.32-2.09 tC hm-2 a-1）作用不同，C、B和L-N为碳吸收汇（C强汇、B和L-N弱汇），M、G、L-T和L-X则为碳排放源（M、G强源、L-T和L-X弱源）。因此，温带小兴安岭草丛沼泽为碳强汇、灌丛沼泽为碳强源、森林沼泽基本维持碳平衡（除M外）。 Abstract:Carbon (CO2 and CH4) emission fluxes, annual net carbon sequestration of vegetation, were studied from seven kinds of natural wetlands (Carex schmidtii marsh-C, Betula ovalifolia-C. schmidtii shrub swamp-G, Alnus sibirica-C. schmidtii swamp-M, B. platyphylla-C. schmidtii swamp-B, Larix gmelinii-C. schmidtii swamp-L-T, L. gmelinii-moss swamp-L-X, and L. gmelinii-Sphagnum spp. swamp-L-N) in Xiaoxing'anling region of China using the static chamber gas chromatography method and the relative growth equation method to evaluate the carbon source or sink of natural forested wetlands based on net ecosystem carbon balance. The results showed that: 1) seasonal dynamics of CH4 emission fluxes from seven kinds of natural wetlands could be divided into three types (single-peak, multi-peak, and emission and absorption alternating type) and CH4 emission flux (0.006-7.756 mg m-2 h-1) exhibited a different trend in M (which was 1.0-1291.7 times greater than the others, P < 0.05) > C, G, B (17.7-649.0 times greater than L-T, L-X, and L-N; P > 0.05) > L-T, L-X, and L-N; 2)seasonal dynamics of CO2 emission fluxes from the seven kinds of natural wetlands could be divided into two types (single-peak and double peak), and CO2 emission flux (157.40-231.06 mg m-2 h-1) exhibited an different trend in G (which was greater 28.7%-46.8% than forested wetlands, P < 0.05) > C(7.4%-22.5% than forested wetlands, P > 0.05) > five kinds of forested wetlands; 3)CH4 emission fluxes from C, G, M, B, and L-N were controlled by soil temperature, but that of L-T and L-X had no significant correlation with soil temperature at 0-40 cm. CO2 emission fluxes from C, G, M, and L-T were controlled by air temperature and soil temperature, and that of B, L-X, and L-N were controlled by air temperature, soil temperature, and the water table level; 4) the annual net carbon sequestration of vegetation ((2.05±0.09)-(6.75±0.27) tC hm-2 a-1) had a different trend in C (greater than the others by 65.4%-229.3%,P < 0.05)> G, B, L-T, L-X, and L-N (greater than M by 80.0%-99.0%, P < 0.05) > M; and 5) the sources and sinks of carbon were significantly different among the seven kinds of natural wetland types (-2.32-2.09 tC hm-2 a-1). For example, C, B, and L-N exhibited varying degrees of carbon sinks, yet M, G, L-T, and L-X exhibited varying degrees of carbon sources. Therefore, marsh wetlands were greater carbon sinks and shrub wetlands were greater carbon sources, yet forested wetlands maintained overall carbon balance (except M) in the Xiaoxing'anling region of China. 参考文献 相似文献 引证文献

Vegetation Diversity in Natural and Restored Forested Wetland Sites in Southeast Arkansas

The loss of forested wetlands in the Lower Mississippi River Alluvial Valley in Arkansas has altered regional vegetation communities. Multiple restoration projects have been established in this region to restore wetlands and the services they provide. In order to return these functions to the environment, microtopographic features were constructed in 2001 at Bob White Memorial Wetlands Research and Teaching Station (Bob White). Vegetation diversity was examined at Cut-Off Creek Wildlife Management Area (Cutoff), a naturally forested wetland, and Bob White, an area formally converted to cropland that is now undergoing forest wetland restoration. Vegetation diversity is one way to determine if restoration efforts are effectively restoring ecosystem structure and functions to natural wetland conditions. Vegetation diversity and composition were examined across three topographical features: hummocks/ridges, swales, and flats. Vegetation diversity was examined in the spring, summer, and fall. Indices were used for determining composition similarities between Bob White and Cutoff. Bob White had a species richness of 33 and Cutoff’s species richness was 47. Beta diversity between the two sites was 76 species, this value is high and suggests there is low similarity between the two sites. Sorensen-Dice Similarity Index value was calculated as 0.05, where on a scale of zero to one a low value indicates low similarity in composition. The low similarity between the two sites suggests that vegetation composition at Bob White has not been fully restored to conditions comparable to a natural setting. An explanation for this is the presence of Baccharis halimifolia (Eastern baccharis). B. halimifolia inhibits other species from colonizing. Another factor for the difference between the vegetation at Bob White and Cutoff is that Cutoff is an older forest. Hydrophyte communities in a forested wetland take 50 years after restoration begins for them to resemble a natural forested wetland. The results from this study provide mixed evidence that restoration at Bob White is succeeding; there is a high percentage of wetlands species, while vegetation lacks similarity. This study improves our understanding of the influence that anthropogenic changes have on wetland functions as agricultural lands are restored to their previous land cover. Ecosystem functions should continue to be monitored to determine time frames as these functions are restored to Bob White

Rearing in natural and recovering tidal wetlands enhances growth and life-history diversity of Columbia Estuary tributary coho salmon Oncorhynchus kisutch population.

This study provides evidence of the importance of tributary tidal wetlands to local coho salmon Oncorhynchus kisutch populations and life-history diversity. Subyearling and, to a lesser extent, yearling O. kisutch life histories utilized various estuary habitats within the Grays River, a tidal freshwater tributary of the Columbia River estuary, including restoring emergent wetlands and natural forested wetlands. Migration timing data, size distributions, estuary residence and scale patterns suggest a predominance of subyearling migrant life histories, including several that involve extended periods of estuary rearing. Estuarine-rearing subyearling O. kisutch exhibited the greatest overall growth rates; the highest growth rates were seen in fish that utilized restoring emergent wetlands. These results contrast with studies conducted in the main-stem Columbia River estuary, which captured few O. kisutch, of which nearly all were hatchery-origin yearling smolts. Restoration and preservation of peripheral and tributary wetland habitats, such as those in the Grays River, could play an important role in the recovery of natural O. kisutch populations in the Columbia River and elsewhere.

Novel ways to assess forested wetland restoration in North Carolina using ecohydrological patterns from reference sites

ABSTRACTRestoring jurisdictional wetland hydrology does not ensure that the hydrologic conditions of any specific natural forested wetland community are recreated. This is especially problematic for a state like North Carolina, which has roughly two dozen different forested wetland communities. Because forested wetland communities align themselves across edaphic and hydrologic gradients, we suggest exploiting these relationships to guide restoration design and set performance standards. However, methods to compare hydrology between multiple reference sites and restored wetlands are lacking. To address this, we studied three different forested wetlands across 13 reference sites to determine which measures of water table levels, based on correlation with plant community composition, would be useful to distinguish these three communities. We then used the best measures of water table levels to assess two restoration sites and compare them with the reference sites. Our results showed that monthly median water table levels encompassing the start of the growing season had the strongest correlation with plant community composition, whereas roughly five other measures also had strong correlations. On the basis of the best measures, both of the restoration sites had water table levels that generally fell within the natural range of the reference sites. Because there was variation in water table levels across each restoration site, the different measures where useful to identify which areas were least similar to the reference sites and might need further monitoring in the future. On the basis of our results, we recommend using community‐specific measures of hydrology to guide and assess forested wetland restoration. Copyright © 2013 John Wiley &amp; Sons, Ltd.

More Than a Pretty Space: Stormwater Treatment Wetlands with Multiple Benefits at Freedom Park, Naples FL

Freedom Park is a 20 ha (50 ac) stormwater runoff quality improvement project in the Gordon River watershed in Naples FL. Constructed ponds and wetlands and restored wetland habitats are integrated into a passive park setting of trails, boardwalks, educational facilities, and natural landscaping. Operated by the Collier County Growth Management Division and the Parks and Recreation Department, the system uses wetlands to reduce nitrogen and phosphorus in water pumped from ditches draining the watershed. Water pumped from the Gordon River supplements the system during dry, low flow seasons and helps reduce river phosphorus and nitrogen loads. Restored natural forested wetlands enhance site biodiversity and enrich the visitor experience. A versatile educational facility supports multiple civic functions that complement and reinforce the steady increase in visitor use since the park opened. Freedom Park demonstrates with excellence how a regional stormwater facility can be designed as a beautiful yet functional community asset.

Identifying ecohydrological patterns in natural forested wetlands useful to restoration design

ABSTRACTWetland restoration projects across the United States commonly lack the species and hydrology of the targeted community being restored. A better understanding of natural wetlands would help restoration project designers achieve community composition and hydrologic regimes that more closely resemble natural conditions. We investigated two different methods to identify patterns in hydrologic regime useful to restoration design. The first method was based on success criteria commonly used by North Carolina wetland mitigation projects. The second method was based on The Nature Conservancy's Indicators of Hydrologic Alteration. To test these two methods, we collected hydrologic and compositional data across the natural variation of nonriverine wet hardwood forest stands, a rare wetland community type commonly restored in North Carolina. Our results show that hydrologic parameters from the first method, based on current success criteria used in North Carolina, are not related to community composition. Hydrologic parameters from the second method, e.g. the maximum water table level over a 3‐day span, explained much of the variation in nonriverine wet hardwood forest community composition. Our results found that clear relationships do exist between hydrologic regime and community composition. Hydrologic parameters that are related to community composition need to be used as success criteria in future restoration designs. This will ensure that projects establish the appropriate hydrologic regime necessary to foster the desired wetland community type. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Influence of Intensive Pine Management on Dipteran Community Structure in Coastal North Carolina

Intensive pine (Pinus spp.) management is a primary land use in the southeastern United States. In eastern North Carolina, intensively managed pine stands often occur on land previously ditched and drained. Because modification of natural vegetation and water sources are known to affect dipteran community structure, we studied effects of intensive pine management on abundance and diversity of dipteran families in the northern coastal plain of North Carolina during 2006 and 2007. We used malaise traps and emergence traps to sample different types of forest stands (n = 143 sample nights) and water sources (n = 147 sample nights) in a managed pine forest and a natural forested wetland. Cecidomyiids were more abundant in stands with canopy cover, chironomids were more abundant at edges between forested stands and open canopy stands, and chloropids were more abundant in open canopy stands. Families Ceratopogonidae, Dolichopodidae, Ephydridae, Muscidae, Psychodidae, and Tipulidae were more abundant in the natural forested wetland than in all types of modified water sources. Dipteran diversity and evenness were highest in stands with open canopy and at forest edges, and highest in the natural forested wetland. Unmanaged, natural stands on the intensively managed landscape did not support a higher abundance or diversity of dipteran families than intensively managed stands. Restoration of natural wetlands may increase dipteran diversity in unmanaged stands. Heliponds, a modified water source, supported a comparable dipteran abundance to that of the natural forested wetland. Increased numbers of heliponds may facilitate higher dipteran abundance in managed pine landscapes.

Reduction of pharmaceutically active compounds by a lagoon wetland wastewater treatment system in Southeast Louisiana

A number of pharmaceutically active compounds (PhACs) have been detected in the aquatic environment as a result of discharges of municipal wastewater. In the state of Louisiana, USA, many municipalities treat wastewater using natural systems, such as lagoons and wetlands, rather than conventional wastewater treatment technologies. Nearly all research to date has focused on the fate of PhACs in conventional treatment plants, not constructed and natural wetlands. In the wastewater treatment plant (WWTP) for Mandeville, Louisiana, USA, wastewater flows of 7600 m 3 d −1 are treated in a series of aeration lagoons (basins), followed by a constructed wetland and UV disinfection, before being discharged into a natural forested wetland (i.e. Bayou Chinchuba) and eventually, Lake Pontchartrain. Thirteen out of the 15 PhACs investigated were detected in the wastewater inflow to the treatment plant. Only 9 of the 13 compounds were above the detection limits at the treatment plant effluent. The concentrations of most compounds were reduced by greater than 90% within the plant, while carbamazepine and sotalol were only reduced by 51% and 82%, respectively. The percent reductions observed in the Mandeville system were greater than reduction rates reported for conventional WWTPs; perhaps due to the longer treatment time (∼30 days). Most target PhACs were not completely removed before discharge into Lake Pontchartrain, although their collective annual loading was reduced to less than 1 kg and down to ppb with significant potential for dilution in the large lake.

Phosphorus retention and soil organic carbon in restored and natural freshwater wetlands

Nutrient (e.g., phosphorus) retention is an important function of wetlands that can improve water quality. We examined soil physical and chemical characteristics and phosphorus (P) sorption capacities in three recently restored herbaceous wetlands (RWs) on previously cultivated soils and three adjacent natural forested wetlands (NWs) on Kent Island, Maryland, USA. Our objective was to compare P retention in these two wetland types. As hypothesized, NW soils differed fundamentally in soil chemistry and had significantly higher total organic carbon (TOC) contents than RW soils (5.7 6 1.7% vs. 1.2 6 0.1%, respectively, p , 0.05). A number of soil properties (bulk density, pH, labile organic and microbial P, total N, and total N: total P ratios) differed between natural and restored wetlands, as expected from the differences in TOC. Concentrations of pyrophosphate-extractable (organically-bound) Al (Al p) were an order of magnitude larger in NW than in RW soils (2099.1 6 365.5 vs. 767.0 6 194.7 kg/ha, respectively). Although past studies have suggested that higher concentrations of organically-bound Al can enhance P sorption, P-sorption capacities were significantly greater in the RW soils, likely due to differences in soil chemistry. In the RWs, 15 soil chemical parameters were significantly correlated with P sorption (based on single factor regression), in- cluding residual Al, oxalate-extractable Al and Fe, clay, HCl-extractable Fe and pyrophosphate-extractable Fe (r 2 5 0.90, 0.89, 0.87, 0.85, 0.83 and 0.82, respectively). In contrast, P sorption in the NWs was correlated only with Alp (r 2 5 0.68). As restored wetland soils are likely in transition from a non-hydric to a hydric state, they should be reevaluated periodically to determine the ultimate effects of this transition on their capacity to retain P.

A Water Chemistry Assessment of Wastewater Remediation in a Natural Swamp

AbstractVarious aspects of water chemistry of a natural forested wetland were studied in order to determine the possibility of using the wetland for advanced wastewater treatment in Louisiana and to evaluate the wastewater effect on swamp water quality. The study was carried out by comparing treatment and control cypress‐tupelo forests separated by a bottomland hardwood forest ridge. The treatment area (231 ha) received secondarily treated municipal wastewater at a rate of 6.3 × 106 L d−1. The calculated hydraulic detention time of the wastewater was 120 d. Electrical conductivity (EC), pH, and concentrations of 5‐d biological oxygen demand (BOD5), dissolved oxygen (DO), solids, nutrients, and trace metals were monitored. Mean concentrations for the wastewater were 14.6 mg L−1 for total N and 2.5 mg L−1 for total P. The dominant form of N in the wastewater was NO3‐N. The swamp system attenuated the NO3‐N by 100%, total Kjeldahl nitrogen (TKN) by 69%, and total P by 66%. It appears that tertiary wastewater treatment was achieved due to the nutrient attenuations. Based upon our findings, we predict that the high N attenuation efficiency would enable the swamp to work well if the N loading rate were doubled. However, P removal was dependent on loading rate, hydraulic retention time, and temperature. The swamp was more efficient in treating wastewater during warm seasons than cool seasons. During the monitoring period, trace metals were not significantly increased in the swamp water because of very low concentrations in the wastewater.

The effects of varied hydraulic and nutrient loading rates on water quality and hydrologic distributions in a natural forested treatment wetland

Abstract Hydrology and water quality distributions in a Louisiana forested waste-water treatment wetland were studied under four different hydraulic loading rates (HLR). Pond discharge, surface-water elevations, and fluorescent dye travel times were recorded to assess surface-water hydrology, and water samples were collected for nitrate, ammonium, phosphate, and suspended solids analyses. Wetted surface area increased with pond discharge rate, and 58 to 66 percent of surface-water flow was concentrated in shallow channels covering only 10 to 12 percent of the total study area. Water residence times were much longer (0.9 to 1.1 days) than minimum dye travel times (2 to 3 hours) through the 4-hectare study area. Relative to study area influent concentrations, study area outflow concentrations of nitrate and total and organic suspended solids were lower, ammonium was higher, and phosphate was generally unchanged. However, there was an increase in concentrations of nitrate, ammonium, and phosphate within 50 m...

Effects of flooding on the forest community in a greentree reservoir 18 years after flood cessation

Greentree reservoir (GTR) management is a common waterfowl habitat management technique used in both the northeastern and southeastern United States. However, this management technique is controversial because greentree reservoir management can cause changes in forest composition and structure. We studied the effects of GTR management at the Montezuma National Wildlife Refuge in central New York by comparing vegetation in permanent plots in two GTRs and a natural forest wetland over 30-year period (preflood and 2 years and 18 years after flood cessation). We detected long-term effects of GTR management on vegetation composition and structure. Red maple and green ash remained the dominant overstory species, but density of green ash saplings was higher (P=0.026) in a natural forested wetland (300 trees/ha) compared to the two GTRs (30–90 trees/ha). Age determinations of several green ash saplings suggest these changes were likely caused by reduced regeneration in the GTRs. Mortality of green ash seedlings in 1996 was greatest in a GTR flooded for 1 year (60%) versus an unflooded GTR (12%) and a natural forested wetland (27%). Overall, shrub density was similar 18 years post-flooding and preflooding, but several species had lower densities (P=0.001–0.031) than a natural forested wetland. Shannon-Weiner diversity index (1.8–2.0) and richness (29–31) of herbaceous species were similar among all sites 18 years after flood cessation. However, two species of fern remained at lower densities (P=0.0001–0.026), while three herbaceous species remained at higher densities (P=0.0001–0.015) 18 years after flood cessation as compared to preflood densities and densities in a natural forested wetland. It is unknown after which year of flooding these changes occurred, but 12 years of GTR management did cause long-term effects on the forest community.

Comparison of Vegetational, Hydrologic, and Edaphic Characteristics of Riverine Forested Wetlands on North Carolina Coastal Plain

Although forested wetlands are relatively abundant on the coastal plain of North Carolina, restoration of forested wetlands is becoming more common since these communities are frequent targets for impact or destruction, especially as a result of road construction projects. Successful restoration of ecosystems is made difficult by a lack of basic knowledge about the soil and hydrologic characteristics of different types of forested wetlands. The plant community composition of two forested wetlands types is described: bottomland hardwood communities and a coastal plain small stream swamp. The edaphic and hydrologic characteristics of each community type were also compared. Many researchers have suggested the construction of detailed water budgets to describe the hydrologic regimes of natural forested wetlands and for use in restoration projects. Although several soil and hydrologic characteristics were associated with variation in plant community composition, the results of this investigation suggest that using a particular flood frequency as a surrogate measure of several flood frequencies may be sufficient to explain this variation. Use of this information would simplify the reconstruction of appropriate hydrologic regimes in forested wetlands and perhaps increase the success of restoration projects.