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1.
Urban development is a leading cause of stream impairment that reduces biodiversity and negatively affects ecosystem processes and habitat. Out‐of‐stream restoration practices, such as stormwater ponds, created wetlands, and restored riparian vegetation, are increasingly implemented as management strategies to mitigate impacts. However, uncertainty exists regarding how effectively they improve downstream ecosystems because monitoring is uncommon and results are typically reported on a case‐by‐case basis. We conducted a meta‐analysis of literature and used response ratios to quantify how downstream ecosystems change in response to watershed development and to out‐of‐stream restoration. Biodiversity in unrestored urban streams was 47% less than that in reference streams, and ecological communities, habitat, and rates of nutrient cycling were negatively affected as well. Mean measures of ecosystem attributes in restored streams were significantly greater than, and 156% of, those in unrestored urban streams. Measures of biodiversity in restored streams were 132% of those in unrestored urban streams, and indices of biotic condition, community structure, and nutrient cycling significantly improved. However, ecosystem attributes and biodiversity at restored sites were significantly less than, and only 60% and 45% of, those in reference streams, respectively. Out‐of‐stream management practices improved ecological conditions in urban streams but still failed to restore reference stream conditions. Despite statistically significant improvements, assessing restoration success remains difficult due to few comparisons to reference sites or to clearly defined targets. These findings can inform future monitoring, management, and development strategies and highlight the need for preventative actions in a watershed context.  相似文献   

2.
We compared potential denitrification and phosphorus (P) sorption in restored depressional wetlands, restored riparian buffers, and natural riparian buffers of central Ohio to determine to what extent systems restored under the U.S. Department of Agriculture's Wetland Reserve Program (WRP) and Conservation Reserve Program (CRP) provide water quality improvement benefits, and to determine which practice is more effective at nutrient retention. We also measured soil nutrient pools (organic C, N, and P) to evaluate the potential for long‐term C sequestration and nutrient accumulation. Depressional wetland soils sorbed twice as much P as riparian soils, but had significantly lower denitrification rates. Phosphorus sorption and denitrification were similar between the restored and natural riparian buffers, although all Natural Resources Conservation Service (NRCS) practices had higher denitrification than agricultural soils. Pools of organic C (2570–3320 g/m2), total N (216–243 g/m2), and total P (60–71 g/m2) were comparable among all three NRCS practices but were greater than nearby agricultural fields and less than natural wetlands in the region. Overall, restored wetlands and restored and natural riparian buffers provide ecosystem services to the landscape that were lost during the conversion to agriculture, but the delivery of services differs among conservation practices, with greater N removal by riparian buffers and greater P removal by wetlands, attributed to differences in landscape position and mineral soil composition. At the landscape, and even global level, wetland and riparian restoration in agricultural landscapes will reintroduce multiple ecosystem services (e.g. C sequestration, water quality improvement, and others) and should be considered in management plans .  相似文献   

3.
Much riparian restoration focuses on establishment of gallery forests, with relatively limited effort to restore herbaceous wetlands as key components of riparian landscape mosaics. Multiple reasons for this include inherent cultural or esthetic preferences, greater availability of scientific knowledge to support riparian forest restoration, and choices of ecological indicators commonly used for monitoring and assessment. Yet riparian herbaceous wetlands have declined dramatically as a result of river regulation and agricultural development, leading to losses of important habitats and ecosystem services that differ from those provided by gallery forests. As an alternative to a single‐minded focus on tree establishment, we advocate restoration of diverse and dynamic habitat mosaics in the context of natural variability of flow and sediment regimes. Landscape context should inform active restoration activities at the local scale, such that riparian forests are not planted in ecologically inappropriate sites. Models are needed to match life history requirements of particular wetland herbaceous plant species with details of flow and sediment transport regimes. We emphasize the importance of herbaceous wetlands as a critical and often overlooked component of riparian ecosystems, and the need for both passive and active restoration of fluvial marshes, sloughs, wet meadows, alkali meadows, off‐channel ephemeral ponds, and other critical floodplain communities associated with herbaceous plant dominance.  相似文献   

4.
Water quality in Upper Sandy Creek, a headwater stream for the Cape Fear River in the North Carolina Piedmont, is impaired due to high N and P concentrations, sediment load, and coliform bacteria. The creek and floodplain ecosystem had become dysfunctional due to the effects of altered storm water delivery following urban watershed development where the impervious surface reached nearly 30% in some sub-watersheds. At Duke University, an 8-ha Stream and Wetland Assessment Management Park (SWAMP) was created in the lower portion of the watershed to assess the cumulative effect of restoring multiple portions of stream and former adjacent wetlands, with specific goals of quantifying water quality improvements. To accomplish these goals, a three-phase stream/riparian floodplain restoration (600 m), storm water reservoir/wetland complex (1.6 ha) along with a surface flow treatment wetland (0.5 ha) was ecologically designed to increase the stream wetland connection, and restore groundwater wetland hydrology. The multi-phased restoration of Sandy Creek and adjacent wetlands resulted in functioning riparian hydrology, which reduced downstream water pulses, nutrients, coliform bacteria, sediment, and stream erosion. Storm water event nutrient budgets indicated a substantial attenuation of N and P within the SWAMP project. Most notably, (NO2 + NO3)-N loads were reduced by 64% and P loads were reduced by 28%. Sediment retention in the stormwater reservoir and riparian wetlands showed accretion rates of 1.8 cm year−1 and 1.1 cm year−1, respectively. Sediment retention totaled nearly 500 MT year−1.  相似文献   

5.
Conservation and restoration of riparian vegetation in agricultural landscapes has had mixed success at protecting in‐stream habitat, potentially due to the mismatch between watershed‐scale impacts and reach‐scale restoration. Prioritizing contiguous placement of small‐scale restoration interventions may effectively create larger‐scale restoration projects and improve ecological outcomes. We performed a multi‐site field study to evaluate whether greater linear length of narrow riparian tree corridors resulted in measurable benefits to in‐stream condition. We collected data at 41 sites with varying upstream tree cover nested within 13 groups in rangeland streams in coastal northern California, United States. We evaluated the effect of riparian tree corridor length on benthic macroinvertebrate communities, as well as food resources, water temperature, and substrate size. Sites with longer riparian corridors had higher percentages of invertebrates sensitive to disturbance (including clingers and EPT taxa) as well as lower water temperatures and less fine sediment, two of the most important aquatic stressors. Despite marked improvement, we found no evidence that macroinvertebrate communities fully recovered, suggesting that land use continued to constrain conditions. The restoration of long riparian corridors may be an economically viable and rapidly implementable technique to improve habitat, control sediment, and counter increasing water temperatures expected with climate change within the context of ongoing land use.  相似文献   

6.
Straightened stream channels and altered and drained wetlands have adversely impacted streams and rivers throughout Midwestern USA, where some of the most dense drainage and riparian ecosystem alteration in the world have occurred. A segment of Grave Creek on The Ohio State University's Marion (OSU Marion) campus in Ohio, USA, with its lack of riparian ecosystems, illustrates the transformation of a natural fluvial ecosystem to an unstable and “simplified” aquatic environment that requires continued maintenance and provides little value to the surrounding landscape or to the university. However, the straight ditch, available adjacent riparian land and existing hydric soil give OSU Marion a great opportunity to demonstrate a project of stream and wetland restoration on a college campus. To restore the natural ecological stability of OSU Marion's “back yard” and to provide habitat improvement to Grave Creek and its surrounding landscape on the OSU Marion campus, we have designed a restoration of 1.1 km of Grave Creek meandering to the east of the existing sewer, using the two-stage channel techniques, and about 0.6–0.8 ha of adjacent wetland. We estimate that restoration on this scale will cost about US$ 200,000–300,000, not including monitoring of the results. To fulfill this project, it is likely that an opportunity for using this restoration in a stream/wetland loss mitigation will present itself in this region of Ohio while a long-term pre- and post-construction monitoring plan and more detailed design would be expected as the next step.  相似文献   

7.
I examined the effect of riparian forest restoration on plant abundance and diversity, including weed species, on agricultural lands along the Sacramento River in California (United States). Riparian forest restoration on the Sacramento River is occurring on a large‐scale, with a goal of restoring approximately 80,000 ha over 160 km of the river. In multiuse habitats, such as the Sacramento River, effects of adjoining habitat types and movement of species across these habitats can have important management implications in terms of landscape‐scale patterns of species distributions. Increased numbers of pest animals and weeds on agricultural lands associated with restored habitats could have negative economic impacts, and in turn affect support for restoration of natural areas. In order to determine the distribution and abundance of weeds associated with large‐scale restoration, I collected seed bank soil samples on orchards between 0 and 5.6 km from adjacent restored riparian, remnant riparian, and agricultural habitats. I determined the abundance, species richness, and dispersal mode of plant species in the seed bank and analyzed these variables in terms of adjacent habitat type and age of restored habitat. I found that agricultural weed species had higher densities at the edge of restored riparian habitat and that native plants had higher densities adjacent to remnant riparian habitat. Weed seed abundance increased significantly on walnut farms adjacent to restored habitat with time since restored. I supply strong empirical evidence that large areas of natural and restored habitats do not lead to a greater penetration of weed species into agricultural areas, but rather that weed penetration is both temporally and spatially limited.  相似文献   

8.
9.
This historical and conceptual overview of riparian ecosystem restoration discusses how riparian ecosystems have been defined, describes the hydrologic, geomorphic, and biotic processes that create and maintain riparian ecosystems of the western USA, identifies the main types of anthropogenic desturbances occurring in these ecosystems, and provides an overview of restoration methods for each disturbance type. We suggest that riparian ecosystems consist of two zones: Zone I occupies the active floodplain and is frequently inundated and Zone II extends from the active floodplain to the valley wall. Successful restoration depends n understanding the physical and biological processes that influence natural riparian ecosystems and the types of disturbance that have degraded riparian areas. Thus we recommend adopting a process-based approach for riparian restoration. Disturbances to riparian ecosystems in the western USA result from streamflow modifications by dams, reservoirs, and diversions; stream channelization; direct modification of the riparian ecosystem; and watershed disturbances. Four topics should be addressed to advance the state of science for restoration of riparian ecosys-tems: (1) interdisciplinary approaches, (2) a unified framework, (3) a better understanding of fundamental riparian ecosystem processes, and (4) restoration po-tential more closely related to disturbance type. Three issues should be considered regarding the cause of the degraded environment: (1) the location of the causative disturbance with respect to the degraded riparian area, (2) whether the disturbance is ongoing or can be elim-inated, and (3) whether or not recovery will occur nat-urally if the disturbance is removed.  相似文献   

10.
For over 40 years, acid deposition has been recognized as a serious international environmental problem, but efforts to restore acidified streams and biota have had limited success. The need to better understand the effects of different sources of acidity on streams has become more pressing with the recent increases in surface water organic acids, or ‘brownification,’ associated with climate change and decreased inorganic acid deposition. Here, we carried out a large scale multi‐seasonal investigation in the Adirondacks, one of the most acid‐impacted regions in the United States, to assess how acid stream producers respond to local and watershed influences and whether these influences can be used in acidification remediation. We explored the pathways of wetland control on aluminum chemistry and diatom taxonomic and functional composition. We demonstrate that streams with larger watershed wetlands have higher organic content, lower concentrations of acidic anions, and lower ratios of inorganic to organic monomeric aluminum, all beneficial for diatom biodiversity and guilds producing high biomass. Although brownification has been viewed as a form of pollution, our results indicate that it may be a stimulating force for biofilm producers with potentially positive consequences for higher trophic levels. Our research also reveals that the mechanism of watershed control of local stream diatom biodiversity through wetland export of organic matter is universal in running waters, operating not only in hard streams, as previously reported, but also in acid streams. Our findings that the negative impacts of acid deposition on Adirondack stream chemistry and biota can be mitigated by wetlands have important implications for biodiversity conservation and stream ecosystem management. Future acidification research should focus on the potential for wetlands to improve stream ecosystem health in acid‐impacted regions and their direct use in stream restoration, for example, through stream rechanneling or wetland construction in appropriate hydrologic settings.  相似文献   

11.
Hydric soil development of riparian wetlands is primarily influenced by the hydrologic connection between the floodplains and the stream channel. Often, the goal of riparian restoration is to revitalize this connectivity through a restructuring of the stream channel and the floodplain; however, the effects of this restructuring on the physical and spatial characteristics of soil properties are rarely considered. The objective of this study was to quantify the impacts of restoration efforts on the spatial characteristics of soil properties by means of a pre‐ and post‐restoration comparison. We determined that the spatial patterns of soil organic matter (SOM) and exchangeable phosphorus (Pex) appeared less variable in the years following restoration than in the years before restoration. Mean SOM significantly decreased after restoration, whereas mean Pex significantly increased. The spatial characteristics and mean concentrations of NO2–NO3 did not differ much between sampling dates. The loss of this spatial patterning in SOM and Pex and the decrease in SOM pools may represent negative impacts of restoration on important ecosystem characteristics. This study demonstrates that soil properties and spatial patterns can be negatively affected by restoration activities potentially hindering ecosystem development and function.  相似文献   

12.
Fens represent a large array of ecosystem services, including the highest biodiversity found among wetlands, hydrological services, water purification and carbon sequestration. Land‐use change and drainage has severely damaged or annihilated these services in many parts of North America and Europe; restoration plans are urgently needed at the landscape level. We review the major constraints on the restoration of rich fens and fen water bodies in agricultural areas in Europe and disturbed landscapes in North America: (i) habitat quality problems: drought, eutrophication, acidification, and toxicity, and (ii) recolonization problems: species pools, ecosystem fragmentation and connectivity, genetic variability, and invasive species; and here provide possible solutions. We discuss both positive and negative consequences of restoration measures, and their causes. The restoration of wetland ecosystem functioning and services has, for a long time, been based on a trial‐and‐error approach. By presenting research and practice on the restoration of rich fen ecosystems within agricultural areas, we demonstrate the importance of biogeochemical and ecological knowledge at different spatial scales for the management and restoration of biodiversity, water quality, carbon sequestration and other ecosystem services, especially in a changing climate. We define target processes that enable scientists, nature managers, water managers and policy makers to choose between different measures and to predict restoration prospects for different types of deteriorated fens and their starting conditions.  相似文献   

13.
Montane riparian meadows foster biodiversity and support critical ecosystem services. A history of exploitation has left most riparian meadows throughout the Mountain West of the United States with incised channels, severely compromising their functionality. Hydrologic restoration of riparian meadows aims to increase overbank flow during spring run‐off and elevate groundwater levels in the dry season. Outcome‐based evaluations of the dominant meadow restoration methods are lacking and needed to ensure objectives are being met and to guide modifications where needed. We completed 1,282 point count surveys from 2009 to 2017 at 173 sampling locations across 31 montane riparian meadows in California restored using partial channel fill techniques (e.g. pond‐and‐plug) to evaluate the expected outcome of increased abundance of meadow birds. We analyzed trends in abundance for 12 focal bird species from 1 to 18 years after hydrologic restoration, substituting space for time in our mixed effects Poisson regression models that included covariates for the amount of riparian deciduous vegetation (RDV) before restoration, stream flow, precipitation, and temperature. We found evidence for a positive effect of time since restoration on abundance for 6 of the 12 species. Although pre‐restoration RDV cover was the most frequently supported predictor of abundance, high pre‐restoration cover of RDV slowed response rates for only two species, suggesting other elements of hydrologic function are also important for meadow birds. Drawing on our results, we provide suggestions for enhancing hydrologic restoration efforts in riparian meadows so that benefits may accrue more quickly to more bird species.  相似文献   

14.
Riparian forest plantings are a well‐established restoration technique commonly used to stabilize banks and intercept nutrient flow from adjacent agricultural fields. Tree species planted for these efforts may not reflect mature forest communities within the same region. Given contemporary research on links between biodiversity and ecosystem functioning, we conducted a leaf‐litter decomposition study to investigate how mixing of detrital resources that reflect forest community composition would regulate in‐stream leaf litter. Leaf litter bags containing material from a mature forest (Liriodendron tulipifera, Acer rubrum, Quercus rubra, full factorial treatments = 7) and a restored riparian forest (Cornus sericea, Fraxinus pennsylvanica, Platanus occidentalis, full factorial treatments = 7) were deployed in a stream reach that experienced riparian reforestation in 2004. Litter from the restored riparian community had less mass remaining (45.28 ± 2.27%) than that from the mature riparian community (54.95 ± 2.19%) after 5 weeks. In addition, mixed litter treatments in the restored riparian community had less mass remaining (40.54 ± 2.37%) than single‐species treatments (51.80 ± 4.05%), a pattern not observed in the mature forest community. Results highlight the importance of planting mixed‐species assemblages as this structure may regulate processes such as decomposition and food‐web structure, processes often not targeted in the restoration plans.  相似文献   

15.
Extensive land-use changes in Iowa have increased erosional processes and the amount of fines deposited on stream beds. Large amounts of fines cover the other bed substrate that are essential habitat for invertebrates and fish. In Iowa and other agricultural Midwestern states, riparian conservation land-uses are being established to minimize sediment inputs to streams. This study compared stream bed substrate composition in reaches adjacent to: riparian forest buffers, grass filters, row-cropped fields, pastures with cattle fenced out of the stream and continuous, rotational and intensively grazed rotational pastures, in three regions of Iowa. The objective was to examine the impacts of the adjacent riparian land-uses on stream bed substrate composition. The percentages of fines in this study ranged from: 36 to 63% in the central region; 10 to 31% in the northeast region; and 22 to 85% in the southeast region. The high percentage of fines in most stream bed reaches indicates high embeddedness. The high embeddedness resulted in the few significant differences in substrate percentages among riparian land-uses. Decades of agricultural land-uses have heavily impacted stream beds and only significant reductions in surface and bank erosion at the watershed scale can begin to reverse this trend. There were indications that riparian forest buffers and to a lesser degree, pastures with cattle fenced out of the stream, could decrease fines resulting in a more diverse substrate composition. Overall, more targeted approaches for the establishment of conservation land-uses in combination with other restoration practices (e.g. in-stream enhancements) are required to successfully decrease fines on stream beds.  相似文献   

16.
Wetland restoration is commonly presented as an important strategy for maintaining and enhancing the water quality and ecological capital of watershed-scale ecosystems. Prioritizing restoration sites on the landscape is often a haphazard process based on widely held, though often untested, assumptions about relationships between watershed characteristics and water quality. We present a framework to target and prioritize wetland restoration locations using both regional and watershed-level screening models. The regression-tree and random forest models presented in this paper identify watershed variables with the strongest relationships to a given water quality parameter, present a clear hierarchy of variable importance, and present approximate thresholds in watershed area where these variables express the greatest impact on water quality. The proportion of watersheds classified as prior-converted agricultural land was an important predictor of both ortho and total phosphorus. Fortunately because prior-converted agricultural lands were historically wetlands, they are often very suitable for wetland restoration. These sites often have poorly-drained soils requiring artificial drainage to be suitable for agriculture. These drainage systems become conduits for transporting phosphorus from agricultural field and to area streams and rivers. Maintaining natural land-cover within stream buffers is identified as another important predictor of water quality. This seems to be especially true with regard to NO3–NO2 concentrations. Our model results support specific management recommendations including: (a) exclusion of agricultural land-uses from riparian buffers, (b) maintaining or increasing watershed-level wetland-cover and (c) reducing wetland fragmentation.  相似文献   

17.
河岸带生态系统退化机制及其恢复研究进展   总被引:25,自引:3,他引:22  
恢复和重建自然和人为干扰导致的退化河岸带生态系统是目前恢复生态学、流域生态学等学科研究的重要内容之一.对河岸带生态系统的干扰表现在河流水文特征改变、河岸带直接干扰和流域尺度干扰3个方面,分别具有不同的影响机制.河流水文特征改变通过改变河岸土壤湿度、氧化还原电位、生物生存环境以及沉积物传输规律对河岸带生态系统产生影响;河岸带直接干扰通过人类活动及外来物种入侵而直接影响河岸带植被多样性;流域尺度干扰则主要表现在河道刷深、河道淤积、河岸带地下水位降低和河流冲刷过程改变等.河岸带生态恢复评价对象包括河岸带生态系统各要素,评价指标已从单一的生态指标转向综合性指标.河岸带生态恢复应在景观或者流域尺度上进行考虑,识别对其影响的生物和物理过程以及导致其退化的干扰因子,通过植被重建与水文调控来进行.扩展研究尺度和研究对象及采用多学科的研究方法将是今后相关研究中的重要问题.  相似文献   

18.
Although public and financial support for stream restoration projects is increasing, long‐term monitoring and reporting of project successes and failures are limited. We present the initial results of a long‐term monitoring program for the Lower Red River Meadow Restoration Project in north‐central Idaho, U.S.A. We evaluate a natural channel design’s effectiveness in shifting a degraded stream ecosystem onto a path of ecological recovery. Field monitoring and hydrodynamic modeling are used to quantify post‐restoration changes in 17 physical and biological performance indicators. Statistical and ecological significance are evaluated within a framework of clear objectives, expected responses (ecological hypotheses), and performance criteria (reference conditions) to assess post‐restoration changes away from pre‐restoration conditions. Compared to pre‐restoration conditions, we observed ecosystem improvements in channel sinuosity, slope, depth, and water surface elevation; quantity, quality, and diversity of in‐stream habitat and spawning substrate; and bird population numbers and diversity. Modeling documented the potential for enhanced river–floodplain connectivity. Failure to detect either statistically or ecologically significant change in groundwater depth, stream temperature, native riparian cover, and salmonid density is due to a combination of small sample sizes, high interannual variability, external influences, and the early stages of recovery. Unexpected decreases in native riparian cover led to implementation of adaptive management strategies. Challenges included those common to most project‐level monitoring—isolating restoration effects in complex ecosystems, securing long‐term funding, and implementing scientifically rigorous experimental designs. Continued monitoring and adaptive management that support the establishment of mature and dense riparian shrub communities are crucial to overall success of the project.  相似文献   

19.
This study investigated the consequences of passive ecological restoration on a riparian habitat and on water quality. The restoration plan consists of excluding livestock by constructing fences along an entire stream 1 m from the stream bed, with the assumption that recovering riparian habitat will restore their ecological processes (e.g., filtration, soil stabilization). We measured responses of riparian plant communities and physico-chemical water quality. We presented data from an 8-year before-after control-impact design across a reference stream and a restored stream in a rural landscape in Normandy, France. Restoration appeared to modify plant communities. After 8 years of restoration, the restored stream had a complex riparian bank, similar to that of the reference stream, with an increase in the number of trees, a decrease in bare soil, and an increase in habitat heterogeneity. Despite this modification, water quality did not improve. The same low water quality in the reference stream demonstrated the need for a watershed-scale approach and for actions to improve agricultural practices before implementing restoration practices at a smaller scale. Nonetheless, the lack of improved water quality does not necessarily mean that the restoration failed. Other functions and services can be provided by excluding livestock.  相似文献   

20.
Human modifications of streams and rivers have caused extensive stream channel and riparian degradation. Cost-effective, rapid assessment tools can be used to better manage such areas by identifying the status of habitats for restoration planning and protection. We used a spatially explicit, reach-scale geographic information system modeling strategy to examine stream channel and riparian condition and prioritize restoration actions. The stream channel condition index uses information on land use, road and railroad density, and sinuosity. The riparian condition index uses calculations of percent forest, patch density, and convexity based on land cover in the floodplain. Reaches were classified into restoration categories based on stream channel and riparian condition model results, land ownership, slope, position in the subwatershed, and adjacency to high-quality habitat. We compared modeled restoration priority rankings with those in the management plan for the East Credit subwatershed in Ontario, Canada. Predicted stream channel restoration priority rankings matched field-based classifications for 86% of the reaches in the East Credit subwatershed. Predicted riparian restoration priority rankings matched field-based classifications for 81% of the reaches. Our methods replicate with fairly good accuracy the results obtained using intensive field surveys and stakeholder input. Managers can use these cost-effective strategy development tools to identify candidate reaches for further study and prioritize stream channel and riparian restoration actions over large regions.  相似文献   

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