How are biodiversity and carbon stock recovered during tropical forest restoration? Supporting the ecological paradigms and political context involved

To meet agendas for biodiversity conservation and mitigation of climate change, large-scale restoration initiatives propose ecological restoration as an alternative that can reconcile these two objectives. In ongoing ecosystem restoration, increased diversity is always associated with increased productivity (and consequent carbon stock), which is among the most important ecosystem functions. The ecological paradigm of this association is that ecosystem biodiversity (B) is positively related to both ecosystem functions and services (EF and ES). However, BEF and BES relationships vary spatially and temporally, which makes understanding these relationships relevant and important for practical restoration actions. In this study, we asked how biodiversity and carbon stock recovery occurs during tropical forest restoration. We reviewed literature of the relationships between BEF and BES in the context of ecological restoration and asked whether ecological restoration can recover both. In addition, we conducted a metadata analysis of studies on the recovery of biodiversity and biomass in regenerating tropical forests (n = 83) to find the best model that describes this relationship. In general, studies showed that ecosystem biodiversity and productivity are positively related, and that restoration can recover both. We found an asymptotic and positive correlation between biodiversity and biomass in tropical forests, suggesting limitation of the mutual gains of these two ecosystem properties during restoration. We discuss these results in the context of ecological theory and the practice of ecological restoration.     

Plant Community Recovery following Restoration in Temporally Variable Riparian Wetlands

Wetlands historically provided many ecosystem services but most have been lost or degraded through land conversion. Recent appreciation for wetland values and increasing ecotourism in the Central Platte River Valley (U.S.A.) has promoted restoration of wet meadow systems, although recovery patterns are not well known. We quantified plant community structure in sloughs (deeper habitats) and adjacent margins (slightly higher elevation) of six wetland sites, restored for 1–7 years at the onset of a 3-year study, and three natural wetlands to assess recovery dynamics. Plant community metrics recovered differentially between habitats. Within restored margins, richness and diversity showed a weak quadratic response with time since restoration, indicating that both indexes overshoot natural levels shortly following restoration. Within sloughs, richness and diversity showed no change with time, suggesting that recovery occurs more quickly in these deeper, moister habitats. Percent similarity of plant communities in restorations and natural wetlands increased linearly over time. However, ordinations of plant community composition showed that recovery was strongly influenced by site-specific hydrology and that recovery may not be a linear trajectory toward natural systems. The analysis and interpretation of plant community dynamics revealed several challenges to restoration assessment, including the role of interannual variability in precipitation, limitations to hydrologic recovery, and temporal variability in plant community structure in natural systems that resulted in "moving targets" for recovery comparisons. Temporal variability in climate must be considered when assessing restoration success in systems where plant community structure is responsive to variable moisture regimes.     

Prairie wetland communities recover at different rates following hydrological restoration

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空间和环境因子对黄河口自然和淡水恢复湿地底栖动物群落的差异影响

生物多样性的形成和维持机制是生态学研究的核心问题,其中环境和空间因子在群落构建中的相对重要性是生态学家面临的重要挑战。为探究黄河口湿地底栖动物群落的关键影响因子,及环境和空间因子对底栖动物群落结构的相对调控作用。于2017年10月与2018年5月对黄河口湿地32个样点（淡水恢复湿地19个和自然湿地13个）的底栖动物和水体理化指标进行采集分析。非度量多维标度排序（NMDS）结果显示,黄河口淡水恢复湿地和自然湿地的底栖动物群落结构显著不同。典范对应分析（CCA）表明,影响淡水恢复湿地底栖动物群落结构的环境因子主要为电导率、盐度和氧化还原电位;而自然湿地底栖动物群落结构主要受pH和无机碳的影响;盐度是两类湿地底栖动物群落组成差异的关键因子。变差分解（VPA）结果显示,环境过滤对淡水恢复湿地底栖动物群落起主导作用;在自然湿地中,空间因子对底栖动物群落具有主要的调控作用,同时环境和空间因子的相互作用也至关重要。本研究明确了黄河口的自然和恢复湿地中环境和空间因素对底栖动物群落特征的相对作用,对黄河三角洲河口湿地中生物多样性的保护和生态系统管理提供参考。     

Does the implementation of environmental flows improve wetland ecosystem services and biodiversity? A literature review

Environmental flow releases are a tool for wetland restoration, but there has been no systematic evaluation of their success. We systematically assessed 102 published studies from a wide range of wetland ecosystems across the globe to determine whether releasing environmental flows could maintain or promote biodiversity and increase ecosystem services, and which strategies were most effective. We found that environmental flow releases remarkably increased regulating services (sediment regulation and water purification) and supporting services (primary production and habitat maintenance), and maintained biodiversity and provisioning services. Biodiversity responses were positive only in river wetlands, and were negative in coastal, lake, and marsh wetlands; the overall delivery of ecosystem services responded positively in all ecosystem types except artificial wetlands. The effects were positive for ecosystem services under all environmental flow regimes, and seasonal minimum flow releases could maintain biodiversity and improve ecosystem services. We also found that long‐term environmental flow releases (years to decades) maintained biodiversity. Values of a change‐in‐flow parameter (D) ranging from 0 to 10% improved both biodiversity and ecosystem services. In summary, long‐term implementation, a high‐flow regime, and D ranging from 0 to 10% for the environmental flows promoted biodiversity and improved ecosystem services around the world, particularly in river wetlands. Regional‐level conclusions might be applicable to guide the implementation of environmental flow releases, but small sample sizes reduce their reliability. We also found that the effect sizes of environmental flow release projects for biodiversity and ecosystem services were significantly and positively correlated in rivers, but not in other wetlands.     

Comparing the diversity and composition of waterbird functional traits between natural,restored, and artificial wetlands

1. The restoration of degraded areas and the creation of artificial ecosystems have partially compensated for the continuing loss of natural wetlands. However, the success of these wetlands in terms of the capacity of supporting biodiversity and ecosystem functions is unclear. Research is needed to improve our understanding of the value of restored and constructed wetlands for functional diversity of freshwater fauna.
2. We compared natural, restored, and artificially created wetlands present within the Doñana Natural Space, Spain and valued as important for waterbirds. We evaluated if these wetlands are equivalent in terms of waterbird functional trait diversity and composition, during both the wintering and breeding seasons. We modelled functional diversity measures and functional group species richness describing species diet, body mass, and foraging techniques with generalised linear mixed models in 20 wetlands monitored between 2006 and 2011. We used three different statistical approaches to evaluate the robustness of our results.
3. Artificial wetlands constructed for conservation failed to reach the functional diversity of natural and restored wetlands. Unexpectedly, artificial ponds constructed for fish production performed better, and even exceeded natural wetlands for functional richness during winter. Fish ponds stood out as having a unique functional composition, connected with increase in richness of opportunistic gulls and decrease of species sensitive to high salinity. Overall, the functional structure of breeding communities was more affected by wetland type than wintering communities.
4. Our findings suggest that compensating the loss of natural wetlands with restored and artificial wetlands results in systems with altered waterbird-supported functions, such as seed dispersal or nutrient cycling. Protection of natural Mediterranean wetlands is vital to maintain the original diversity and composition of waterbird functional traits. Furthermore, restoration must be prioritised over the creation of artificial wetlands, which, even when intended for conservation, may not provide an adequate replacement.

     

不同生态恢复方式下生态系统服务与生物多样性恢复效果的整合分析

全球范围内关键生态系统服务的减少使人类社会面临巨大的威胁,生物多样性是生态系统提供各种产品和服务的基础。生态恢复工程对退化的生态系统服务和生物多样性进行修复,对于缓解人类环境压力具有非常重要的意义。长期的理论和实践工作形成了多种生态恢复措施:(1)单纯基于生态系统自我设计的自然恢复方式,(2)人为设计对环境条件进行干预,反馈影响生态系统的自我设计,(3)人为设计对目标种群和生态系统进行直接干预和重建。这3类恢复方式可以在不同程度上定向的影响生态系统的恢复进程,反映了人类对生态系统的低度、中度和高度介入。哪种恢复方式和介入程度能够实现更好的恢复效果,是生态恢复学中的一个关键问题,但到目前为止,虽广有争议,却无定量的分析和结论。针对这个空白,通过对ISI Web of Knowledge数据库中生态恢复相关文献的整合分析,基于数学统计的方法定量比较在不同条件下低度介入(自然恢复)、中度介入(环境干预)和高度介入(直接干预)3种恢复方式对生态系统服务与生物多样性的恢复效果。论文从4个方面展开研究:(1)低度、中度、高度介入生态恢复方式的划分,(2)比较3大类介入方式对生态系统服务和生物多样性恢复效果的差异,(3)不同气候条件、生态系统类型和恢复时间等背景因素的影响,(4)生物多样性恢复和生态系统服务恢复之间的关系。研究结果揭示了不同生态恢复方式的适用条件,以及对生物多样性和生态系统恢复相互关系的作用,对生态恢复实践中恢复方式的选择有指导作用。对未来的研究也有启示意义,如针对特定生态系统服务或具体研究问题进一步探索低度、中度和高度介入生态恢复方式的作用规律和机制;将地区的社会经济水平、生态系统的受损程度等因素纳入生态恢复方式的考察,以最优化生态恢复成本-效率等。     

Should ‘wetlands’ cover all aquatic ecosystems and do macrophytes make a difference to their ecosystem services?

The Ramsar Convention has gradually expanded the scope of the term ‘wetland’ to bring under its umbrella all kinds of inland freshwater (and saline) ecosystems as well as many marine ecosystems. It is not possible to develop a common framework for the study, management or policy of such a large and divergent assemblage of habitats with water being a single shared feature. In this paper, I argue that wetlands are distinct from deep open water systems such as rivers, lakes and reservoirs. The restriction of macrophytes (except the free floating plants like salvinia and water hyacinth) to shallow water habitats helps distinguish between wetlands and deep water systems. Following an ecosystem service approach, I discuss that wetlands are generally characterized by the occurrence of macrophytes, which critically contribute to their provisioning, regulating, supporting and cultural ecosystem services that differ significantly from those of the microphyte (phytoplankton)-dominated deep water habitats. I argue that wetlands do lie adjacent to deep and open water systems (including large rivers), which interact with them regularly and influence their biodiversity, hydrology, water quality and functioning, depending upon their relative areal extent and characteristics of the macrophyte community, but that only the littoral zones between the mean highest and lowest water levels (and stream banks and the floodplains beyond them in the case of rivers) should be treated as wetlands. Shallow lakes devoid of macrophytes because of eutrophication are degraded wetlands that need to be restored.     

Meta‐Analysis of Lost Ecosystem Attributes in Urban Streams and the Effectiveness of Out‐of‐Channel Management Practices

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.     

Net Ecosystem Production and Carbon Greenhouse Gas Fluxes in Three Prairie Wetlands

In central North America, prairie wetlands provide many important ecosystem services including attenuating floods, improving water quality, and supporting biodiversity. However, over half of these wetlands have been drained for agriculture. Relatively little is known about the functioning of these ecosystems either in their natural state or restored after drainage. We characterized net ecosystem production and carbon greenhouse gas (GHG) fluxes (carbon dioxide [CO₂] and methane) in the open-water zones of three prairie wetlands over two ice-free seasons. These wetlands included a natural site and sites restored 3 and 14 years prior to study (hereafter “recently restored” and “older restored”). We also assessed how two techniques for estimating metabolic status, the diel oxygen method (used to measure NEP) and net CO₂ fluxes, compared. The diel oxygen method suggested that the restored wetlands were net heterotrophic across years, whereas the natural wetland was net heterotrophic in 1 year and net autotrophic in the other. Similar conclusions arose from quantifying net CO₂ fluxes, although this technique proved to be relatively insensitive for understanding metabolic status at a daily temporal scale owing to the influence of geochemical processes on CO₂ concentrations. GHG efflux was greatest from the recently restored wetland, followed by the older restored and natural wetlands. Overall, GHG flux rates were high and variable compared with other inland aquatic ecosystems. Although restoration may progressively return wetland functioning to near-natural states, our results highlight the necessity of preventing wetland drainage in the first place to preserve ecosystem functions and services.     

Ecosystem Recovery Across a Chronosequence of Restored Wetlands in the Platte River Valley

Wet meadows in the Platte River valley (PRV) consist of linear wetlands in mesic prairie matrix systems that have been degraded and diminished for agriculture. Restoration in this region is a widespread practice that involves land contouring and seeding native species, however ecosystem recovery following restoration has never been examined. We quantified recovery trajectories and rates of above- and belowground plant biomass, soil physical and chemical properties, and C and N pools in a chronosequence of six restored wet meadows in relation to three natural wetlands. Within each site, we sampled sloughs (deeper habitats) and adjacent margins (slightly higher elevation) for three consecutive years. Varying hydrologic regimes between habitats resulted in differential patterns in ecosystem measurements (bulk density, C mineralization) in both natural and restored wetlands. Total aboveground biomass (TAB), root biomass, root C and N storage, total soil C and N, microbial N, and extractable N increased with years restored in both margins and sloughs. The model predicted rates of increase did not differ between habitats, but elevations of linear regressions were higher in sloughs than margins for root N, total soil C, total soil N, MBN, and extractable total N (P < 0.05). Our results suggest that bulk density and soil organic matter (SOM) represent two useful, easily measured indices of ecosystem recovery, because they were correlated with many pools and fluxes of C and N. Furthermore, we conclude that most change in ecosystem structure and function during the first decade following restoration occurs in shallow soil depths, and ecosystem recovery varies with subtle differences in elevation and associated plant community structure.     

恢复生态学——退化生态系统生物多样性恢复的有效途径

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滇西北高原入湖河口退化湿地生态修复效益分析

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Biodiversity dynamics of freshwater wetland ecosystems affected by secondary salinisation and seasonal hydrology variation: a model-based study

Freshwater wetlands worldwide are under threat from secondary salinisation and climate change. Given that many freshwater wetlands naturally have highly variable hydrology, it is important to understand the combined effects of salinity and water regime on wetland biodiversity. Here a mathematical model has been developed to explore the biodiversity dynamics of freshwater wetland ecosystems affected by secondary salinisation and seasonal hydrology variation. The model shows that seasonal hydrological change can drive the wetland ecosystem into a stable oscillatory state of biodiversity, with the same period as the wetting and drying cycle. The initial condition of a wetland mediates the ecological response of the wetland ecosystem to salinity and seasonal variability. There are two manifestations of stability that occur in relation to wetland biodiversity: monostability and bistability. In model simulations, some wetland ecosystems may respond to the effects of seasonal change quickly, while others may do so more slowly. In ‘slow response’ wetlands, seasonal variability has a weak impact on the ecosystem properties of stability, resilience, sensitivity and the species richness–mean salinity relationship. In contrast, ‘fast response’ wetlands are seasonally controlled heavily. Seasonal variability can play a critical role in determining ecosystem properties. Changes in the strength of seasonality can induce the transition between monostability and bistability. Seasonal variability may also reduce wetland resilience, exacerbating the risk of secondary salinisation. On the other hand, seasonal variability may provide opportunities for the restoration of salinised wetlands by increasing their sensitivity to management actions and facilitating recovery processes. Model simulations show that the response of the stable biodiversity oscillation to changing mean salinity is dependent on seasonality strength (primarily for fast response wetlands) and other wetland conditions. Generally, there are two types of wetland responses to changes in mean salinity: type 1 wetlands exhibit a graded response of species richness (a surrogate for biodiversity), whereas a hysteretic response occurs in type 2 wetlands. Species diversity displays critical behaviour: regime shifts in diversity occur at the thresholds of mean salinity, strength of seasonality or initial species diversity. The predictions are consistent with previously-published field observations in salinised freshwater wetlands. Handling editor: D. Hamilton     

Step back from the forest and step up to the Bonn Challenge: how a broad ecological perspective can promote successful landscape restoration

We currently face both an extinction and a biome crisis embedded in a changing climate. Many biodiverse ecosystems are being lost at far higher rates than they are being protected or ecologically restored. At the same time, natural climate solutions offer opportunities to restore biodiversity while mitigating climate change. The Bonn Challenge is a U.N. programme to restore biodiversity and mitigate climate change through restoration of the world's degraded landscapes. It provides an unprecedented chance for ecological restoration to become a linchpin tool for addressing many environmental issues. Unfortunately, the Forest and Landscape Restoration programme that underpins the Bonn Challenge, as its name suggests, remains focused on trees and forests, despite rising evidence that many non‐forest ecosystems also offer strong restoration potential for biodiversity and climate mitigation. We see a need for restoration to step back to be more inclusive of different ecosystem types and to step up to provide integrated scientific knowledge to inform large‐scale restoration. Stepping back and up will require assessments of where to restore what species, with recognition that in many landscapes multiple habitat types should be restored. In the process, trade‐offs in the delivery of different ecosystem services (e.g. carbon, biodiversity, water, albedo, livestock forage) should be clearly addressed. We recommend that biodiversity safeguards be included in policy and implemented in practice, to avoid undermining the biophysical relationships that provide ecosystem resilience to climate change. For ecological restoration to contribute to international policy goals will require integrated large‐scale science that works across biome boundaries.     

沿海滩涂围垦对生态环境的影响研究进展

沿海滩涂湿地生态系统,典型的生态脆弱区,既是地球表面最为活跃的自然区域,又承载着人类的生存与发展,其生态环境面临着巨大压力。在社会经济发展和人口增长的推动下,沿海国家大力从海洋中争夺陆地,围填海造地和围垦开发成为许多沿海地区和国家缓解人地矛盾的主要方法。在此背景下,对沿海滩涂围垦历史进行简述,从滩涂土壤性质、生物多样性、土地利用变化及景观格局、生态安全和生态系统服务等5个方面综述了人类围垦活动的生态环境影响。随着围垦时间的增加,滩涂土壤在脱盐过程中累积养分,逐渐熟化,土壤物理、化学和生物特性朝着有利于人类利用的方向变化;植物物种多样性呈不断增加的总体趋势,且随着生境的变化,陆生昆虫和土壤动物逐渐替代湿地典型的底栖动物和水鸟;土地利用方式从自然状态转变为以人工方式为主,景观格局表现为破碎化程度升高、多样性降低和优势度上升;从自然景观为主的自然湿地生态系统转为以人工景观为主的人工陆地生态系统过程中,供给服务的价值是唯一处于增长趋势的生态系统服务功能,但供给服务的价值增加量小于调节服务、文化服务和支持服务的减少量致使生态系统服务总价值降低,而且滩涂湿地面临着土地资源安全、水资源安全、生物入侵以及自然灾害加剧等风险。在全球气候变化背景下,如何权衡资源利用与环境保护并实现人与自然共生,是海岸带湿地生态系统在人类围垦活动中面临的重要难题之一。因此,未来应以机理研究为基础,以长期定位监测为手段,以综合集成的研究体系及对策制定为目标,不断深化沿海滩涂开发利用对生态环境影响的研究,为推动人类围垦活动下沿海滩涂湿地生态系统的可持续发展提供参考。     

白洋淀流域生态系统服务评估及其调控

政策制定者在制定土地利用相关政策时需要权衡各方面的利益关系,协调资源保护和经济发展之间的关系.由于缺乏有效的评价与权衡办法,目前对这方面研究还较少.采用InVEST模型,评价了白洋淀流域7种服务功能指标,分析了其空间分布特征.通过情景(政策情景与保护情景)分析,较好的反映了农业直接经济收入与服务功能之间的关系.结果表明:生物多样性、水源涵养、土壤保持和固碳重要区域主要分布在流域西部、北部和流域中部山区;水质保护和授粉重要区域主要分布于流域东部、南部和中部平原区.政策情景下,产水量第二,农业产出有所下降,固碳能力较保护模式差,N/P输出最少.保护情景下产水量最大,农田产出价值不变,氮磷保持与政策情景差不多,但固碳效果最好.通过权衡不同情景下服务功能得失,筛选既不损害流域居民实际经济收入,又能使得水文服务功能得到提高的管理模式.研究表明InVEST模型可以很好的用于对自然资本评估和空间化特征分析,通过建立不同情景,评价结果可以用于权衡不同管理策略下服务功能得失,是一种评价和预测自然资本变化的有效方法,对政策制定和策略筛选具有重要的指导意义.     

Upstream river morphology and riparian land use overrule local restoration effects on ecological status assessment

River restoration is a central issue of present-day River Basin Management. Unfortunately, many studies have shown limited ecological improvements, hypothesizing catchment influences and missing donor populations as main impeding factors. This study evaluates the ecological status after restoration at 46 river reaches in light of catchment influences upstream. Three groups of environmental parameters were investigated: (i) riparian land use and (ii) physical habitat quality in different lengths upstream of the restorations and (iii) land use in the whole catchment upstream. Ecological quality ratios of standardized fish, invertebrate and macrophyte samples were used as response variables. The results imply that sub-catchment variables influence the ecological status more than local habitat improvements. In particular, fish and invertebrate ecological status was positively linked to percent deciduous forest upstream of restored sites, while macrophytes revealed an opposite trend. Furthermore, we found a strong linkage of site-scale ecological status and physical habitat quality up to 5 km upstream of the restorations; the more natural were riparian land use and river habitat quality upstream, the higher was the chance of a good ecological quality in restored reaches. We conclude that site-scale restoration measures are likely to be unsuccessful, if the sub-catchment physical habitat upstream is degraded.     

Comparing the Fish and Benthic Macroinvertebrate Diversity of Restored Urban Streams to Reference Streams

Urbanization is associated with substantial losses to stream biological diversity throughout the United States' mid‐Atlantic. Stream restoration has been used to improve stream conditions and, in part, to ameliorate these losses. However, the relationship between restoration and recovery of biological diversity is unclear. Our objective was to critically examine the efficacy of urban stream restorations with regard to biological diversity. We compared restored urban streams to urban nonrestored, nonurban, and reference (minimally degraded) streams using five measures each of fish and benthic macroinvertebrate diversity. Both multivariate and univariate statistical analyses show biological diversity of restored urban streams to be similar to nonrestored urban streams and lower than nonurban and reference streams. Restored urban sites showed no apparent increase in biological diversity through time, while diversity decreased at two of the reference streams coincident with increased urban development within their catchments. Our results indicate that restoration approaches commonly used regionally as in these urban streams are not leading to recovery of native stream biodiversity. Evidence from several sources indicates a need for dramatic changes in restoration approach, and we argue for a watershed‐scale focus including protection of the least impacted streams and adopting other land‐based actions within the watershed where possible.     

Plankton respiration and biomass as functional indicators of recovery in restored prairie wetlands

Reliable ecological indicators of wetland integrity are necessary for assessing recovery of restored wetlands; yet, little consensus currently exists on which indicators are most appropriate. We employed indicators derived from simple, standard measures of ecosystem function selected on the basis of ecological succession theory developed by [Science 164 (1969) 262; Bioscience 35 (1985) 419], which suggests that respiration:biomass ratios should increase in disturbed systems due to the diversion of energy from growth to maintenance. This hypothesis holds potential for the development of a simple ecological indicator and therefore was tested among prairie wetlands restored after drainage disturbance. No difference was observed in respiration:biomass ratios in restored wetlands and reference wetlands designated as controls. Plankton respiration or biomass may be poor indicators of disturbance because plankton responds quickly to re-establishment of a wetland hydrology regime and/or because different plankton species may have redundant function. We suggest employing more revealing assessment techniques that employ simultaneous examination of ecosystem structure and function to better characterize subtle or lingering effects of wetland disturbance after restoration.