Achieve Restoration Goals Research Articles

Monitoring Growth Performance of Naturally Regenerated Woody Species in an Enriched Pine Stand, Sri Lanka

Monitoring growth performance of newly recruited plant species after applying several silvicultural treatments in monoculture plantations is important to evaluate the success of forest restoration. This study was conducted in 2015 to determine the growth performance of the naturally regenerated woody plant species in an unrestored (UP) and a restored (RP) Pinus caribaea Morelet plantation, in lower Hantana, Sri Lanka. In RP, partial thinning of pines followed by enrichment planting of four broad-leaved tree species in 2003 and total thinning of pines was initiated in 2009. In both sites fifteen plots (5x5m) and within each of them three subplots (1x1m) were demarcated randomly. The height of seedlings (SE, 300 cm in height) and dbh of SA2 and TR in all the plots were recorded. Collectively, 417 individuals (RP=298, UP=119) representing 28 species (RP=24, UP=12) and 22 plant families (RP=18, UP=13) survived by the end of the six months. The mean monthly increment of height (MMIH)of survived species in RP was higher for all the life forms except for SE (SE=1.35, SA1=1.61, SA2= 1.38, TR= 4.45 cmmo-1) than in UP (SE=2.06, SA1= 0.17, SA2= 0.00, TR= 1.65 cmmo-1). The MMIH of trees was significantly higher in RP than UP. The mean monthly increment of dbh (MMID) of survived individuals in RP was higher for both SA2 (0.017 cm per mo-1) and TR (0.027 cm per mo-1) than in UP (SA2= 0.0007, TR= 0.024 cmmo-1). The MMID of SA2 was significantly higher in RP than UP Of the 24 species tested in all four life form categories in RP, 19 (SE=39%, SA1=56%, SA2=69%, TR=85% of the species)had MMIH exceeding 1 cm mo-1while eight (SA2=5%, TR=26%) had dbh increment exceeding 0.05 cm mo-1. In UP, only five species (SE=60%, SA1=100%, SA2=25%, TR=77%of the species) had MMIH exceeding 1cm while one species (Alstonia macrophylla)(SA2=25%, TR=22%) had MMID exceeding0.05 cm mo-1. As the growth performance of the naturally regenerated woody species in RP was higher than UP, we conclude that restoration of pine plantation in mountainous regions of Sri Lanka, using silvicultural techniques is successful in achieving restoration goals. Keywords: Growth performance, Natural regeneration, Pinus plantation, Restoration

Restoration islands: a tool for efficiently restoring dryland ecosystems?

Restoration islands are concentrated plantings in strategic locations, created to efficiently use resources to achieve restoration goals. These methods have been used effectively in mesic ecosystems, particularly tropical forests, where the goal of island plantings is often to “nucleate” across a degraded area, providing a seed source for spread outside the planted area. Here, we consider how an island strategy might be used to achieve restoration goals in dryland ecosystems, where limited resources and large areas of degraded land make restoration extremely challenging. In contrast to more productive areas, spread or “nucleation” from restoration islands in drylands may not occur or occur more slowly than required by most management time frames. Despite this, small‐scale, more intensive island plantings may still be useful for achieving short‐term goals, such as weed control, fire management, erosion control, and creation of wildlife habitat. Over the long term, island plantings could serve the same nucleation function as in other ecosystems and serve as repositories for genetic diversity within highly fragmented native systems. Here, we highlight the opportunities for using these high‐intensity, targeted planting methods in dryland ecosystems, provide the guidelines for establishing islands to achieve short‐ and long‐term restoration goals, and identify the areas where additional research is needed to understand the value of restoration islands in dryland ecosystems.

Using structured decision‐making to set restoration objectives when multiple values and preferences exist

Achieving global targets for restoring native vegetation cover requires restoration projects to identify and work toward common management objectives. This is made challenging by the different values held by concerned stakeholders, which are not often accounted for. Additionally, restoration is time‐dependent and yet there is often little explicit acknowledgment of the time frames required to achieve outcomes. Here, we argue that explicitly incorporating value and time considerations into stated objectives would help to achieve restoration goals. We reviewed the peer‐reviewed literature on restoration of terrestrial vegetation and found that while there is guidance on how to identify and account for stakeholder values and time considerations, there is little evidence these are being incorporated into decision‐making processes. In this article, we explore how a combination of stakeholder surveys and workshops can be used within a structured decision‐making framework to facilitate the integration of diverse stakeholder values and time frame considerations to set restoration objectives. We demonstrate this approach with a case of restoration decision‐making at a regional scale (southeast Queensland, Australia) with a view to this experience supporting similar restoration projects elsewhere.

Scaling Up Restoration Efforts in the Pacific Islands: A Call for Clear Management Objectives, Targeted Research to Minimize Uncertainty, and Innovative Solutions to a Wicked Problem

Today, restoration of resilient native ecosystems that minimize extinction risk and maximize ecosystem services has never been more important. Success stories, such as that of Hakalau Forest National Wildlife Refuge and papers in this special feature, demonstrate the value in large-scale efforts. However, the number of decision makers involved and siloed agencies responsible for land and nearshore coastal management, incomplete or contradictory knowledge regarding community and ecosystem dynamics, the large costs associated with complete restoration, and the interconnectedness of restoration decisions with social, cultural, policy, and economic dimensions, clearly classify the process of attempting large-scale restoration of degraded systems as a wicked problem. We wish to outline three focal areas that specifically address each of the challenges associated with wicked problems and that may improve the likelihood of achieving restoration goals. First, managers and decision makers must identify clear objectives that will guide decisions regarding restoration actions. Second, research funded through conservation initiatives should be aimed at reducing uncertainty in ways that increase the probability of choosing a set of management actions likely to have a desirable outcome. Finally, we need innovative solutions that borrow from industries that have already discovered economy of scale, as well as partnerships among those in the fields of social science, economics, policy, and the natural sciences. The collection of articles in this special feature illustrate how objective-driven studies, high-value research in areas of uncertainty, and collaborations among economists, cultural practitioners, and scientists can move us toward the identification of optimal solutions. Ultimately, we wish to restore systems in ways that reduce conservation reliance and result in resilient, self-sustaining native ecosystems.

Understorey plant community composition reflects invasion history decades after invasive Rhododendron has been removed

Abstract A growing awareness of the destructive effects of non‐native invasive species has led to a massive increase in removal programmes around the world. However, little is generally known about what happens to sites following the removal of the invasives and the implicit assumption that the native community will return, unaided, to pre‐invasion conditions is often left untested. We assessed recovery of the native understorey plant community following removal of the non‐native invasive Rhododendron ponticum L. from Scottish Atlantic oak woodland. We recorded understorey community composition in sites covering a gradient of increasing R. ponticum density, and across a separate series of sites covering a chronosequence of time since R. ponticum removal. We then compared both of these series to the target community found in uninvaded sites. We also analysed differences in soil chemistry between the sites to test for chemical legacy effects of invasion in the soil. Native understorey cover declined as R. ponticum density increased, with bryophytes dropping to less than a third of the cover present in uninvaded sites and forbs and grasses being completely extirpated under dense stands. Cleared sites showed no evidence of returning to the target community, even after 30 years of recovery, and instead formed a bryophyte‐dominated “novel community,” containing few of the typical oak woodland vascular plants. Contrary to expectation, soil pH, C:N ratio and nutrient concentrations (N, P, K, Ca and Mg) were not affected by the invasion of R. ponticum, and chemical legacy effects in the soil were not responsible for the failure of the native community to revert to pre‐invasion conditions. Instead, we hypothesise that the rapid formation of a bryophyte mat, coupled with the often substantial distances to potential seed sources, hindered vascular plant recolonisation. Synthesis and applications. Clear evidence of invasion history can be detected in the understorey plant community even decades after the successful removal of the invasive Rhododendron ponticum L. This finding demonstrates that native communities may be unable to recover effectively of their own accord following invasive species removal, and will require further management interventions in order to achieve restoration goals.

Effects of between‐site variation in soil microbial communities and plant‐soil feedbacks on the productivity and composition of plant communities

Summary A critical challenge in the science and practice of restoration ecology is to understand the drivers of variation in restoration outcomes. Soil microbial communities may have a role in explaining this variation due to both site‐to‐site variation in the composition of soil microbial communities and due to variation that can arise due to plant‐soil feedbacks. We tested the relative importance of between‐site variation in soil microbial community composition and plant‐soil feedbacks in shaping plant community composition and ecosystem function. We used a standard two‐phase plant‐soil feedback design. Soil inoculum was collected from four tallgrass prairie sites. Then, soils were conditioned separately with nine plant species, and conditioned soils were used to inoculate prairie community mesocosms. In a separate experiment using soil from an additional site we tested conditioned soil samples for the abundance of arbuscular mycorrhizal fungi (AMF) and rhizobia. Site of soil origin and plant‐soil feedbacks both had effects on the composition and productivity of our plant communities, and the magnitudes of these effects were similar. We also found changes in the abundance of AMF and rhizobia due to plant‐soil feedbacks and that AMF abundance were associated with differences in plant community composition. These results indicate that the composition of soil communities due to site‐to‐site variation and plant‐soil feedbacks are both important determinants of plant community composition and productivity. Our results also suggest that AMF and rhizobia are key microbial functional groups underlying plant‐soil feedback effects. Synthesis and applications. Site‐to‐site variation in soil communities can explain some variation in restoration of plant communities. Since plant‐soil feedback effects of restored plant species do not overcome this variation, knowledge of soil microbial communities present at a site prior to initiation of restoration efforts may improve predictability of restoration outcomes, and reintroduction of some components of the soil community may be necessary to achieve restoration goals. Additionally, by understanding variation due to plant‐soil feedbacks, restoration practitioners can choose plant species for reintroduction that will create favourable soil conditions, including promoting microbial mutualists. Plant‐soil feedbacks should also make it possible to increase heterogeneity in soil microbial communities, leading to increases in beta diversity in plant communities.

Economic Opportunities and Trade-Offs in Collaborative Forest Landscape Restoration

We modeled forest restoration scenarios to examine socioeconomic and ecological trade-offs associated with alternative prioritization scenarios. The study examined four US national forests designated as priorities for investments to restore fire resiliency and generate economic opportunities to support local industry. We were particularly interested in economic trade-offs that would result from prioritization of management activities to address forest departure and wildfire risk to the adjacent urban interface. The results showed strong trade-offs and scale effects on production possibility frontiers, and substantial variation among planning areas and national forests. The results pointed to spatially explicit priorities and opportunities to achieve restoration goals within the study area. However, optimizing revenue to help finance restoration projects led to a sharp reduction in the attainment of other socioecological objectives, especially reducing forest departure from historical conditions. The analytical framework and results can inform ongoing collaborative restoration planning to help stakeholders understand the opportunity cost of specific restoration objectives. This work represents one of the first spatially explicit, economic trade-off analyses of national forest restoration programs, and reveals the relative cost of different restoration strategies, as well scale-related changes in production frontiers associated with restoration investments.

Grass Mortality and Turnover Following Core Rangeland Restoration Practices

In rangelands, management interventions have sought to minimize disturbances that decrease survival of perennial grasses to avoid compositional shifts toward less desirable species. However, the effects of rangeland management techniques on perennial grass survival and turnover are not known for individual species because the discipline has largely focused on structural metrics, measuring cover or biomass rather than tracking individual plants. In this study, we quantified perennial grass survival and recruitment in response to core rangeland restoration practices across multiple soil types to determine the potential for different interventions to cause shifts to undesirable grass community assemblages. We mapped individual grass tufts and recorded basal area annually. We used these maps to track survival and recruitment of grasses in response to mechanical brush removal, chemical woody plant control, and low-intensity prescribed burning. Additionally, we performed ordinations of the grass community to explore compositional shifts resulting from management interventions. We found perennial grass mortality to be higher for mechanically treated plots on all soil types than it was in chemically treated plots, burned plots, or untreated controls. Levels of mortality from fire were similar to baseline mortality in control plots for all soil types. However, relative species turnover was variable among soils and treatments. Brush removal only resulted in compositional shifts on sandy soils, where annual grasses and species capable of rapid expansion following disturbance became dominant. Differential responses are related to differences in species turnover, which is a function of individual grass species mortality and recruitment mediated by interactions between management approach and abiotic conditions. Given this response variability, understanding effects of management actions on perennial grass turnover and the potential for those actions to result in a community shift toward less desirable species is necessary for managers to achieve restoration goals on encroached rangelands.

Attributes of successful actions to restore lakes and estuaries degraded by nutrient pollution

As more success is achieved in restoring lakes and estuaries from the impacts of nutrient pollution, there is increased opportunity to evaluate the scientific, social, and policy factors associated with achieving restoration goals. We examined case studies where deliberate actions to reduce nutrient pollution and restore ecosystems resulted in ecological recovery. Prospective cases were identified from scientific literature and technical documents for lakes and estuaries with: (1) scientific evidence of nutrient pollution; (2) restoration actions taken to mitigate nutrient pollution; and (3) documented ecological improvement. Using these criteria, we identified 9 estuaries and 7 lakes spanning countries, climatic regions, physical types, depths, and watershed areas. Among 16 case studies ultimately included, 8 achieved improvements short of stated restoration goals. Five more were successful initially, but condition subsequently declined. Three of the case studies achieved their goals fully and are currently managing to maintain the restored condition. We examined each case to identify both common attributes of nutrient management, grouped into ‘themes’, and variations on those attributes, which were coded into categorical variables based on thorough review of documents associated with each case. The themes and variables were organized into a broad conceptual model illustrating how they relate to each other and to nutrient management outcomes. We then explored relationships among the themes and variables using multiple correspondence analysis (MCA). Results of the MCA suggested that the attributes most associated with achieving restoration goals include: (1) leadership by a dedicated watershed management agency; (2) governance through a bottom-up collaborative process; (3) a strategy that set numeric targets based on a specific ecological goal; and (4) actions to reduce nutrient loads from all sources. While our study did not provide a comprehensive road map to successful nutrient management, it suggested attributes that could be emulated in future efforts. The quantitative approach that was applied could be used to provide ongoing analysis as new examples of nutrient management success emerge.

Integrating Limiting-Factors Analysis with Process-Based Restoration to Improve Recovery of Endangered Salmonids in the Pacific Northwest, USA

Two approaches to ecological restoration planning, limiting-factors analysis and process-based restoration, are employed in efforts to recover endangered salmonid species throughout the Pacific Northwest of North America. Limiting-factors analysis seeks to identify physical limitations to fish production that may be addressed by habitat restoration; it is known as the “Field of Dreams” hypothesis (i.e., if you build it, they will come). Process-based restoration, in contrast, assumes that protection and/or restoration of watershed-scale processes will best achieve self-sustaining habitat features that support salmon populations. Two case studies from the Columbia River basin (northwestern USA) display current efforts to integrate these two restoration approaches to improve salmonid populations. Although these examples both identify site-specific habitat features to construct, they also recognize the importance of supporting key watershed processes to achieve restoration goals. The challenge in advancing the practice of restoration planning is not in simply acknowledging the conceptual benefits of process-based restoration while maintaining a traditional focus on enumerating site-specific conditions and identifying habitat-construction projects, but rather in following process-based guidance during recovery planning and, ultimately, through implementation of on-the-ground actions. We encourage a realignment of the restoration community to truly embrace a process-based, multi-scalar view of the riverine landscape.

Phylogenetic diversity is maintained despite richness losses over time in restored tallgrass prairie plant communities

Summary Ecosystem restoration is an important tool for mitigating biodiversity loss and recovering critical ecosystem services to humanity, but restoration rarely takes into account the evolutionary attributes of the community being restored. Phylogenetic diversity (PD) represents a potentially valuable measure of restoration success because it can correlate with functional trait diversity that drives ecosystem function. However, PD patterns in restored communities are rarely assessed. We surveyed plant communities in restored tallgrass prairies 2–19 years old and calculated two PD measures, SESMNTD and SESMPD, of the communities and seed mixture applied to sites. We also identified high‐threat exotic species present in each site to determine whether PD of the seed mixture applied was related to resistance against invasion. We show that PD in North American tallgrass prairie restorations, as measured by both SESMNTD and SESMPD, is maintained over time even as richness declines. Neither the resulting community PD nor invasion by high‐threat exotic species was affected by PD of the seed mixture used in site restoration. Thus, simply maximizing PD of seed mixtures without considering the particular component species is unlikely to help achieve restoration goals. Synthesis and applications. These results suggest that species losses over time are not biased towards species with or without close relatives in the community. If phylogenetic diversity (PD) reflects functional trait diversity in communities, then local declines in species richness may not necessarily mean the loss of ecosystem function in restoration projects. However, PD of restored communities may be limited by low establishment rates for most species. Conservation practitioners should consider PD with careful planning to maintain overall community diversity and potentially maximize ecosystem function and services in restorations. This perspective will require a deeper understanding of the relationships between phylogenetic relatedness and traits associated with competition and fitness.

Using filter‐based community assembly models to improve restoration outcomes

SummaryEcological filter models derived from community assembly theory can inform restoration planning by highlighting management actions most likely to affect community composition. Despite growing interest in these models, many restoration studies solely manipulate a single assembly filter – the biotic filter by altering interspecific competition – while ignoring abiotic and dispersal filters that may also influence restoration success.To examine how manipulating all three assembly filters (biotic, abiotic, dispersal) affected restoration in an annual‐type grassland, we seeded native forbs from the same functional group as a target invader to increase biotic resistance to invasion (biotic filter), cut standing biomass and either removed it or returned it to plots as litter to alter light conditions (abiotic filter), and added native forbs at different seeding rates to alter density of establishing native populations (dispersal filter). We measured grassland restoration success by recording native species and invader cover in plots.The addition of native species with phenological and morphological traits similar to the target invader reduced invasion and increased native populations, but only in litter‐free plots when high densities of native seed were added.Seeding two species with functional traits similar to the invader was more effective for achieving restoration goals than seeding just one functionally similar species. As such, trait differences among restoration species, even species belonging to the same functional group, may increase biotic resistance to invasion in restored communities.Litter removal altered native–invader interactions. When litter was left on the plots, added natives did not reduce invader cover. However, when litter was removed, added natives led to declines in invader cover.Increasing native seeding rates led to larger native populations and increased invasion resistance.Synthesis and applications. In this study, simultaneously manipulating biotic, abiotic and dispersal filters was necessary to optimize grassland restoration outcomes. In particular, the biotic filter only contributed to successful restoration outcomes under abiotic and dispersal conditions that were created through management actions specifically targeting these two additional filters. Restoration planning based on filter models should incorporate actions that target all three assembly filters, rather than solely focusing on the biotic filter.

Ecologically relevant geomorphic attributes of streams are impaired by even low levels of watershed effective imperviousness

Urbanization almost inevitably results in changes to stream morphology. Understanding the mechanisms for such impacts is a prerequisite to minimizing stream degradation and achieving restoration goals. However, investigations of urban-induced changes to stream morphology typically use indicators of watershed urbanization that may not adequately represent degrading mechanisms and commonly focus on geomorphic attributes such as channel dimensions that may be of little significance to the ecological goals for restoration. We address these shortcomings by testing if a measure characterizing urban stormwater drainage system connections to streams (effective imperviousness, EI) is a better predictor of change to ecologically relevant geomorphic attributes than a more general measure of urban density (total imperviousness, TI). We test this for 17 sites in independent watersheds across a gradient of urbanization. We found that EI was a better predictor of all geomorphic variables tested than was TI. Bank instability was positively correlated with EI, while width/depth (a measure of channel incision), bedload sediment depth, and frequency of bars, benches, and large wood were negatively correlated. Large changes in all geomorphic variables were detected at very low levels of EI (<2–3%). Excess urban stormwater runoff, as represented by EI, drives geomorphic change in urban streams, highlighting the dominant role of the stormwater drainage system in efficiently transferring stormwater runoff from impervious surfaces to the stream, as found for ecological indicators. It is likely that geomorphic condition of streams in urbanizing watersheds, particularly those attributes of ecological relevance, can only be maintained if excess urban stormwater flows are kept out of streams through retention and harvesting. The extent to which EI can be reduced within urban and urbanizing watersheds, through techniques such as distributed stormwater harvesting and infiltration, and the components of the hydrologic regime to be addressed, requires further investigation.

A sediment budget for the southern reach in San Francisco Bay, CA: Implications for habitat restoration

article i nfo The SouthBay Salt Pond RestorationProject isoverseeing the restorationof about 6000 haof formercommercial salt-evaporation ponds to tidal marsh and managed wetlands in the southern reach of San Francisco Bay (SFB). As a result of regional groundwater overdrafts prior to the 1970s, parts of the project area have subsided below sea-level and will require between 29 and 45 million m 3 of sedimentto raise the surfaceof the subsided areas to elevations appropriate for tidal marsh colonization and development. Therefore, a sufficient sediment supply to the far south SFB subembayment is a critical variable for achieving restoration goals. Although both major tributaries to far south SFB have been seasonally gaged for sediment since 2004, the sediment flux at the Dumbarton Narrows, the bayward boundary of far south SFB, has not been quantified until recently. Using daily suspended-sediment flux data from the gages on Guadalupe River and Coyote Creek, combined with continuous suspended-sediment flux data at Dumbarton Narrows, we computed a sediment budget for far south SFB during Water Years 2009-2011. A Monte Carlo approach was used to quantify the uncertainty of the flux estimates. The sediment flux past Dumbarton Narrows from the north dominates the input to the subembayment. However, environmental conditions in the spring can dramatically influence the direction of springtime flux, which appears to be a dominant influence on the net annual flux. It is estimated that up to sev- eral millennia may be required for natural tributary sediments to fill the accommodation space of the subsided former salt ponds, whereas supply from the rest of the bay could fill the space in several centuries. Uncertainty in the measurement of sediment flux is large, in part because small suspended-sediment concentration differences between flood and ebb tides can lead to large differences in total mass exchange. Using Monte Carlo simulations to estimate the random error associated with this uncertainty provides a more statistically rigorous method of quantifying this uncertainty than the more typical sum of errors approach. The results of this study reinforce the need for measurement of estuarine sediment fluxes over multiple years (multiple hydrologic conditions) to adequately detail the variability in flux. Additionally, the timing of breaching events for the resto- ration project could be tied to annual hydrologic conditions to capitalize on increased regional sediment supply. Published by Elsevier B.V.

Refining thresholds in coupled fire–vegetation models to improve management of encroaching woody plants in grasslands

Summary Restoration priorities are typically established without quantitative information on how to overcome the thresholds that preclude successful restoration of desirable ecosystem properties and services. We seek to demonstrate that quantifying ecological thresholds and incorporating them into management‐oriented frameworks provide a more comprehensive perspective on how the threshold concept can be applied to achieve restoration goals. As an example, restoration actions have been largely unsuccessful when based on prevailing ecological knowledge of fire‐based thresholds in nonresprouting Juniperus woodland. We build on previous threshold‐based research and link well‐established models from applied fire physics with a widely applied ecological positive feedback model of woody plant encroachment to introduce a more comprehensive understanding of the mechanism influencing fire intensity and juniper mortality. Our coupling of physical and ecological fire models revealed a critical knowledge gap, a lack of a quantitative estimate on the critical surface fire intensity required to cause mortality of Juniperus ashei trees, which limits the linking of scientific knowledge from these two disciplines. To quantify the relationship between fire intensity and J. ashei mortality, we input data from a previous experiment into Byram's fireline intensity model. This critical surface fire intensity–mortality threshold was estimated to be Is &gt; 160 kJ m−1 s−1. This value establishes a specific threshold that managers should target when attempting to use restoration to collapse J. ashei woodlands. Synthesis and applications. For scientific information associated with the threshold concept to be useful to practitioners, specific information is needed that demonstrates how to use restoration activities to overcome thresholds and collapse the current, degraded state in favour of a more desired ecological state. With this in mind, we present a broadly applicable decision support model within a state and transition framework that identifies the ecological states where the surface fire intensity–mortality threshold is most likely to meet restoration objectives and provides examples of how fuel properties that drive fire intensity should be targeted in restoration to surpass this threshold.

Assessing the success of mine restoration using Hemiptera as indicators

Understanding trends in assemblage composition of key invertebrate groups can provide important insight into the ‘condition’ of, or changes in, the environment. Species density, abundance and composition of Hemiptera (true bugs) were assessed in jarrah (Eucalyptus marginata) forest and a chronosequence of restored bauxite mine pits near Boddington, Western Australia, in order to evaluate how restoration was progressing. A significant difference was uncovered for hemipteran species density between the youngest restored treatment and forest. In contrast, hemipteran composition was distinct between the forest and all restored treatments. Hemipteran composition was associated with the presence of the plant species Conostylis setigera and Trichocline spathulata, and plant structure between 160–180 cm and 260–280, plus soil pH. Restoration was successful in returning Hemiptera with respect to species density, but restoration was yet to attain a similar composition of Hemiptera to that of unmined forest, despite some of the restored sites being almost 20 years old. These results are similar to those of other studies that have assessed the response of Hemiptera to disturbance, and highlight the need to wait for considerable periods in order to achieve restoration goals. This study also confirms the utility of Hemiptera as bioindicators of environmental ‘condition’ and change.

Linking ecological function to species composition in ecological restoration: Seed removal by ants in recreated woodland

AbstractEvaluations of ecological restoration typically focus on associating measures of structural properties of ecosystems (e.g. species diversity) with time since restoration efforts commenced. Such studies often conclude a failure to achieve restoration goals without examining functional performance of the organism assemblages in question. We compared diversity and composition of ant assemblages and the rates of seed removal by ants in pastures, 4‐ to 10‐year old revegetated areas and remnants of Cumberland Plain Woodland, and an endangered ecological community in Sydney, Australia. Ant assemblages of forest remnant sites had significantly higher species richness, significantly different species composition and a more complex functional group structure in comparison with ant assemblages of pasture and revegetated sites, which did not differ significantly. However, the rates of seed removal by ants in revegetated sites were similar to those in forest remnants, with the rates in pasture sites being significantly lower. Approximately, one‐third of all ant species were observed to remove seeds. Forest remnant sites had significantly different assemblages of seed removing ant species from those in pasture and revegetated sites. These results demonstrate that similar ant assemblages of unrestored and restored areas can function differently, depending on habitat context. Evaluation of restoration success by quantifying ecosystem structure and function offers more insights into ecosystem recovery than reliance on structural data alone.

A simulation of the development and restoration of old-growth structural features in northern hardwoods

Thinning treatments in second-growth forest may be a practical means of accelerating the development of certain old-growth structural features in regions where old stands are presently uncommon. We used CANOPY, an individual-tree model calibrated with data from thinned and unthinned stands, to simulate effects of thinning on growth rates and development of old-growth structural features in second-growth northern hardwoods. Three simulated, moderately heavy thinnings over a period of 45 years nearly doubled the predicted mean radial increment of canopy trees, percent of stand basal area in large trees, and area of canopy gaps. Compared to untreated stands, thinned stands had fewer dead trees per ha, but the dead trees were larger in size and the overall volume of snags and logs was little affected. In a 77-year old even-aged stand, moderately heavy thinning was predicted to reduce the time needed to attain the minimum structural features of an old-growth forest from 79 to 36 years. Simulated treatments in an older, uneven-aged stand gave mixed results; the moderately heavy treatment stimulated individual tree growth, but the removal of some medium-sized canopy trees in conjunction with natural mortality delayed the development of old-growth structure. Total volume of dead wood may still be deficient under the thinning regimes investigated in this study, but predicted live-tree structure 45 years after moderately heavy thinning was typical of stands in the advanced transition and steady-state stages of old-growth development. Results suggest that thinning can substantially accelerate the development of old-growth structure in pole and mature northern hardwoods, but response in older, uneven-aged stands is more modest, and treatments in these stands may need to be more conservative to achieve restoration goals.

Stream ecosystem responses to spatially variable land cover: an empirically based model for developing riparian restoration strategies

Summary1. The restoration of native, forested riparian habitats is a widely accepted method for improving degraded streams. Little is known, however, about how the width, extent and continuity of forested vegetation along stream networks affect stream ecosystems.2. To increase the likelihood of achieving restoration goals, restoration practitioners require quantitative tools to guide the development of restoration strategies in different catchment settings. We present an empirically based model that establishes a relationship between a ‘stress’ imposed at different locations along a stream by the spatial pattern of land cover within catchments, and the response of biologically determined ecosystem characteristics to this stress. The model provides a spatially explicit, quantitative framework for predicting the effects of changes in catchment land cover composition and spatial configuration on specific characteristics of stream ecosystems.3. We used geospatial datasets and biological data for attached algae and benthic macroinvertebrates in streams to estimate model parameters for 40 sites in 33 distinct catchments within the mid‐Atlantic Piedmont region of the eastern U.S. Model parameters were estimated using a genetic optimisation algorithm. R2 values for the resulting relationships between catchment land cover and biological characteristics of streams were substantially improved over R2 values for spatially aggregated regression models based on whole‐catchment land cover.4. Using model parameters estimated for the mid‐Atlantic Piedmont, we show how the model can be used to guide restoration planning in a case study of a small catchment. The model predicts the quantitative change in biological characteristics of the stream, such as indices of species diversity and species composition, that would occur with the implementation of a hypothetical restoration project.

Adaptive management and adaptive governance in the everglades ecosystem

The Everglades is an intensively managed ecosystem where control of the water has allowed agricultural, urban and economic development, while struggling to meet biodiversity conservation goals. The over 100 year history of control began in response to a disastrous series of floods and droughts followed by environmental crises at an ecosystem scale. Each of these events precipitated technological fixes that extended control of water resources. Institutional structures have been continually reorganized over the last century to meet shifting social objectives, the latest of which is ecosystem restoration. However, the basic response, which employs engineering and technological solutions, is a type of social trap, where governmental mandates, planning-based paradigms and vested interests all interact to inhibit the resolution of chronic environmental issues. Experience from other resource systems indicates that in such an inherently complex system wrought with multiple uncertainties, restoration must be discovered through experimentation and learning embraced by adaptive management. Though minimal steps towards adaptive management have been made, we argue that adaptive forms of experimentation and governance are needed to resolve chronic resource issues and achieve restoration goals.