Enhance Restoration Success Research Articles

Grassland restoration on linear landscape elements – comparing the effects of topsoil removal and topsoil transfer

Artificial linear landscape elements, including roads, pipelines, and drainage channels, are main sources of global habitat fragmentation. Restoration of natural habitats on unused linear landscape elements can increase habitat quality and connectivity without interfering with agricultural or industrial development. Despite that topsoil removal and transfer are widely applied methods in restoration projects, up to our knowledge these were previously not compared in the same study system. To address this knowledge gap, we compared spontaneous vegetation recovery after the elimination of positive (embankments) and negative landscape scars (drainage channels) in lowland alkaline landscapes in South Hungary. The novelty of our study is that we compared the fine-scale and landscape-scale results of both methods. At the fine scale, we monitored the spontaneous vegetation development on the created open surfaces in the first, second and fourth year after restoration in 160 permanent plots per year. For characterizing the habitat changes on the landscape scale, we prepared habitat maps and assigned naturalness scores to each patch before and after the restoration activities. Both restoration methods resulted in a rapid vegetation recovery at the fine scale, progressing toward the reference state. In the topsoil removal treatment, a large part of the soil seed bank was removed; therefore, the colonization of the bare surface was a slower process. Seeds of halophytes, including the endemic and protected Suaeda pannonica, were probably present in the deeper soil layers, and these species became established in the restored surfaces, despite being absent in the surrounding vegetation. For restoring vegetation cover, topsoil transfer was a more rapid option; however, vegetation closure and competition by generalist species and weeds hampered the establishment of target species. The removal of the landscape scars by both methods made the sites accessible for grazing. At the landscape scale, the two methods had different effects: there was a slight increase in the habitat naturalness in the topsoil removal site, and a slight decrease in the topsoil transfer site because of weed encroachment. Spreading an upper layer of nutrient-poor soil with low amounts of weed seeds, direct propagule transfer, and targeted grazing regimes could enhance restoration success.

Seeding success: Integrating seed dispersal networks in tropical forest restoration

AbstractWhile the reassembly of fruit‐frugivore interactions remains at the forefront of tropical forest restoration, seed dispersal networks emerge as a potential approach to enhance restoration success. This review explores the integration of seed dispersal networks in tropical forest restoration, with the aims of (1) synthesizing important findings in the literature, (2) detailing potential biases in utilizing network theory, and (3) addressing current knowledge gaps and future directions for the field. We first highlight the importance of combining phytocentric and zoocentric approaches when sampling for seed dispersal interactions, as different methodologies have varying effects on network measures, and combining approaches can foster a more comprehensive understanding of dispersal interactions. Furthermore, when integrating seed dispersal networks into restoration goals, we suggest a highly connected and species‐rich network is desirable for earlier stages of forest succession where community turnover and transient interactions are pivotal. Nested patterns may emerge throughout varying stages of forest succession, and identifying generalist species that make up nested patterns may be useful for restoration practitioners in both early and later stages of forest regeneration. Modularity should be highest at later stages of succession to maintain community structure and stability, and connector species may play important roles in facilitating seed dispersal across temporal scales. Finally, we emphasize the importance of site‐specific long‐term datasets, chronosequences, and studies at large spatial scales to continue to understand network reassembly as a function of tropical forest succession and to develop effective strategies that enhance the recovery of tropical forest ecosystems.

Atoll Mangrove Progradation Patterns: Analysis from Jaluit in the Marshall Islands

AbstractLow-lying islands are vulnerable to coastal erosion, and mangroves, which can mitigate erosion, have suffered enormous losses in recent decades owing to human impacts. Previous studies have little investigated mangrove shores on atolls, which may face combined multiple threats. We analysed the large Marshall Islands atoll of Jaluit, at a higher resolution than previous spatial change studies, finding that mangrove shorelines prograded seawards over the last seven decades. Biogeomorphic colonisation processes were characterised from transects along ~ 14.6 km of shorelines. Mangrove progradation occurred in patterns of arc-shapes evident of long-shore drift deposition, patch expansion of offshore mangrove colonisers, and linear shoreline advance. Significant differences in the rates of expansion were identified, with arc-shaped colonisation showing the fastest rates of expansion. However, linear shoreline advance was the most frequent expansion pattern showing greater than three-fold more classified transects than arc-shaped colonisation and patch expansion. These results have implications for low island mangrove restoration. Applying mangrove planting patterns mimicking these different natural colonisation processes may enhance restoration success in ecosystem-based adaptation projects to mitigate sea level rise vulnerability. Results from this study show that atoll mangrove shorelines demonstrate resilience during past sea level rise rates, and that rates of expansion vary according to patterns of biogeomorphic colonisation.

Temporal dynamics in the composition of bird communities along a gradient of farmland restoration.

Revegetation plantings are a key activity in farmland restoration and are commonly assumed to support biotic communities that, with time, replicate those of reference habitats. Restoration outcomes, however, can be highly variable and difficult to predict; hence there is value in quantifying restoration success to improve future efforts. We test the expectation that, over time, revegetation will restore bird communities to match those in reference habitats; and assess whether specific planting attributes enhance restoration success. We surveyed birds in 255 sites in south-east Australia, arranged along a restoration gradient encompassing three habitat types: unrestored farmland (paddocks), revegetation plantings (comprising a chronosequence up to 52 years old) and reference habitats (remnant native vegetation). Surveys were undertaken in 2006/2007 and again in 2019, with data used to compare bird assemblages between habitat types. We also determined whether, in the intervening 12 years, bird communities in revegetation had shifted toward reference habitats on the restoration gradient. Our results showed that each habitat contained a unique bird community and that, over time, assemblages in revegetation diverged away from those in unrestored farmland and converged toward those in reference habitats. Two planting attributes influenced this transition: the bird assemblages of revegetation were more likely to have diverged away from those of unrestored farmland (with scattered mature trees) 12 years later if they were located in areas with more surrounding tree cover, and were mostly ungrazed by livestock (compared with grazed plantings). Our results highlight three key ways in which revegetation contributes to farmland restoration: (1) by supporting richer and more diverse bird assemblages than unrestored farmland, (2) by enhancing beta diversity in rural landscapes through the addition of a unique bird community, and (3) by shifting bird assemblages toward those found in reference habitats over time. However, revegetation plantings did not replicate reference habitats by ~40-50 years in our region, and complete convergence may take centuries. These findings have implications for environmental offset programs and mean that effective conservation in farmland environments depends on the retention and protection of natural and seminatural habitats as a parallel management strategy to complement restoration.

Nursery-reared coral outplanting success in an upwelling-influenced area in Costa Rica

Introduction: Environmental and intrinsic factors such as seawater temperature, salinity, nutrient concentration, upwelling, species, and life history can influence coral outplant survival and growth, and in consequence, the effectiveness of restoration. Thus, it is key to understand how these factors can shape coral outplant performance to ensure the long-term success of a restoration program. 
 Objective: To establish the survival and growth rate of outplanted coral nursery-reared colonies of branching Pocillopora spp. and massive corals Pavona gigantea, Pavona clavus, and Porites lobata in Bahía Culebra, North Pacific of Costa Rica, and to determine whether the site of origin of the coral fragment and the presence of seasonal upwelling affected the growth of Pocillopora outplants. 
 Methods: From September 2020 to September 2021, we monitored the survival, health, and growth of 30 Pocillopora spp. colonies from six donor sites, and 31 fragments of massive species (P. gigantea [n = 18], P. clavus [n = 8], P. lobata [n = 5]) that were outplanted to a degraded reef. We recorded in situ seawater temperature, salinity, and nutrient concentration. 
 Results: By the end of the year, 100 % of the Pocillopora spp. outplants survived. Survival was 71.4 % for P. clavus, 47.5 % for P. gigantea, and 20 % for P. lobata. Coral tissue loss and predation marks were observed at least once in 71 % of massive outplants. Pocillopora spp. colonies increased their initial area in 333.1 %, at a rate of 9.98 ± 1.69 cm yr-1. The site of origin of the outplant influenced growth rate, but not the presence of seasonal upwelling. Massive species fragments grew at a rate of 1.35 ± 0.24 cm yr-1 for P. clavus, 1.48 ± 0.21 cm yr-1 for P. gigantea, and 0.61 cm yr-1 for P. lobata, with no differences among them. 
 Conclusions: Environmental conditions at site level allow for high survival and growth of Pocillopora spp. outplants, previously considered as sensitive to stressors, and point towards acclimation to seasonal upwelling. Although survival of massive species was lower, developing a multi-species approach is key to enhance restoration success.

Exploring local perceptions, implementation, benefits, and limitations of community‐based restoration projects in Mexico

Environmental restoration success depends on the involvement of local communities, from the co‐design of projects to their execution and follow‐up. Nonetheless, community‐based restoration has been poorly assessed and is frequently not incorporated into planning of institutional programs. Based on an online questionnaire addressing rural and indigenous communities involved in restoration projects across Mexico, we explored the local perceptions of restoration efforts, the main characteristics of actors' responsibilities in projects, benefits, and limitations of activities, and recommendations for performing community‐based programs. Results showed that communities have an active participation from the assessment of goals to implementation of activities. Restoration is an important activity to generate revenues, recover the use of natural resources, and foster conservation. Most projects considered local knowledge, but were performed for a short term and constrained by funding. Restoration activities mainly focused on vegetation recovery, while animals were widely used for monitoring progress of actions. Our results suggest that communities are no longer involved as mere labor forces, but have an active role as critical decision makers in all process stages and in providing recommendations to enhance joint efforts with other stakeholders. Still, according to the literature review of Mexican restoration projects that contextualized our findings, less than 6% of the publications reported the incorporation of communities into restoration projects. This highlights the relevance of our work to portray community‐restoration and emphasizes the importance to promote collective responses to sustainably manage natural resources, while strengthening a collaborative restoration agenda with communities, which is critical to enhance restoration success worldwide.

Initiating and upscaling mussel reef establishment with life cycle informed restoration: Successes and future challenges

Worldwide, coastal ecosystems are rapidly degrading in quality and extent. While novel restoration designs include facilitation to enhance restoration success in stressful environments, they typically focus on a single life-stage, even though many organisms go through multiple life-stages accompanied by different bottlenecks. A new approach – life cycle informed restoration – was designed to ameliorate multiple bottlenecks throughout an organism's life cycle. It has successfully been tested on a small scale to facilitate intertidal bivalve reef formation in the Netherlands and Florida. Yet, it remains unknown whether this approach can be scaled to ecosystem-relevant scales. To test whether life cycle informed restoration is upscalable, we conducted a large-scale restoration experiment using blue mussel reefs as a model system. In our experiment, we used biodegradable structures to temporarily facilitate mussel reef formation by providing early-life settlement substrates, and subsequently, reduce post-settlement predation on an intertidal flat in the Wadden Sea, the Netherlands. The structures were placed in 10 × 20 m plots, mimicking bands found in natural mussel beds, spread out across 650 m, and were followed for two years. Our results show that the structures enhance mussel biomass (0.7 ± 0.2 kg DW m−2), as mussels were absent in bare plots. However, biomass varied within plots; in intact structures it was 60 times higher (1.2 ± 0.2 kg DW m−2) than in those that became buried (0.02 ± 0.009 kg DW m−2). Next to burial, 18–46% of the structures were lost due to technical failure, especially during winters at this exposed site. We show that the life cycle informed restoration principle works, but we encountered technical challenges due to larger scale processes (e.g. sedimentation). Furthermore, environmental information is essential for site selection, and for restoration, the functioning of such structures should be tested under extreme conditions before upscaling.

The joint effect of host plant genetic diversity and arbuscular mycorrhizal fungal communities on restoration success

Abstract Drastic loss in the area and quality of natural and semi‐natural habitats over the last hundred years has placed biodiversity and related ecosystem functions under substantial threat. Restoration of degraded ecosystems is among the main solutions to counteract this trend. However, past restoration efforts have not always led to the anticipated halt of species loss, neither have they ensured sustainable provision of vital ecosystem services. It has been proposed that one of the reasons for the failure to stop biodiversity decline through ecological restoration lies in overlooking the importance of improving ecosystem complexity, including the recovery of interaction networks with co‐adapted species. In the current review, we show how simultaneously addressing these often unnoticed aspects has the potential to advance the success of ecological restoration. We focus on the relationship between the community composition of arbuscular mycorrhizal (AM) fungi and the genetic diversity of the host plant population as an example. Most terrestrial plant species associate with AM fungi, which have a fundamental role in ecosystem functioning through enhancing plant nutrition and tolerance to abiotic and biotic stress. Previous studies have highlighted the significance of these symbionts in increasing the restoration success of degraded habitats. In parallel, the role of gene‐level diversity within plant populations for creating sustainable ecosystems has increasingly been acknowledged over the last years. However, considering the possible interaction of these two aspects, that is taking AM fungal communities and genetic diversity of host plant populations into account to enhance restoration success, has received no attention. Evidence suggests that the genetic diversity within a host plant population can have a significant effect on the ability of the host plant to benefit from mycorrhizal associations. We suggest that novel genomic approaches, such as community genetics and landscape genomics, should be applied to shed light on this aspect of plant–fungal interactions and be incorporated in restoration planning. Fundamental understanding of the nature of such associations can benefit from using restoration frameworks as large‐scale experimental settings. A free Plain Language Summary can be found within the Supporting Information of this article.

Do early‐successional weeds facilitate or compete with seedlings in forest restoration? Disentangling abiotic versus biotic factors

Abstract Semi‐arid forests need cost‐effective restoration strategies to address their severe degradation. Tree shelters are often used to minimize abiotic and biotic stress during seedling establishment. We asked if early‐successional weeds act as a natural shelter by facilitating native seedlings, contingent on abiotic and biotic stressors and seedling ecological strategy. We conducted a manipulative weed exclusion experiment at a semi‐arid site in South Texas targeted for large‐scale forest restoration to discern the net effect of weeds on the growth and survival of target thornscrub tree and shrub seedlings. We assessed the roles of contrasting seedling ecological strategies (fast vs. slow growth habit), temporal variation in abiotic stress, microclimate and mammalian herbivory in modulating weed–seedling interactions. Ungulate herbivory on seedlings was common, of similar frequency across most species, but not diminished by the presence of weed neighbours. On average, seedlings growing adjacent to weed neighbours experienced modest but non‐significant increases in both height and mortality after 6 months, relative to weed‐excluded areas. However, seedlings without significant herbivory and adjacent to weed neighbours grew more vigorously (increased height and branching) during hot and dry periods, particularly those species with a fast growth habit. Although seedling light‐saturated photosynthetic capacity (Asat) and air temperature were unaffected by weed presence during hot and dry periods, afternoon light levels were reduced by approximately 50%, possibly indicative of lower leaf temperatures and improved seedling water status. Our results show that realizing the facilitative potential of weeds in semi‐arid forest restoration requires minimizing mammalian herbivory and temporally separating competition for resources. Managing for intermediate but not excessive levels of forb canopy cover is likely required to reduce high radiation loads and reduce transpiration without adverse competitive effects. Longer‐term experiments manipulating cover crop identity, cover and mammalian herbivory will inform whether forbs can be effectively exploited to enhance restoration success at large scales.

Inclusion of Intra- and Interspecific Facilitation Expands the Theoretical Framework for Seagrass Restoration

Restoration is increasingly utilized as a strategy to stymie the loss of coastal habitats. Coastal habitat restoration has predominantly emphasized designs that minimize physical stress and competition. As evidence of the pervasiveness of this approach, we conducted a global survey of seagrass restorationers and found a strong affinity for stress-avoidant designs with adult shoots in dispersed rather than aggregated configurations. To test the alternative hypothesis that including positive interactions can enhance restoration success, we experimentally incorporated: (i) interspecific facilitation (clam additions) into seed sowing, and (ii) both intra- and interspecific facilitation (planting a single-large versus multiple-small patches and adding clams) into shoot planting. Clam additions to seeds significantly enhanced plant biomass and patch size; and nutrient analysis suggested the causative mechanism was clam enhancement of available nitrogen. In contrast, adult outplant growth was enhanced by intra- but not inter-specific facilitation. Dispersed configurations consistently declined, whereas large-intact patches, which had the same initial biomass as dispersed plots, increased in patch area and doubled in shoot density. These results demonstrate that expanding restoration strategies to include positive interactions with respect to seagrass ontogeny has the capability to switch the trajectory of restoration from failure to success.

Priming of Marine Macrophytes for Enhanced Restoration Success and Food Security in Future Oceans

Marine macrophytes, including seagrasses and macroalgae, form the basis of diverse and productive coastal ecosystems that deliver important ecosystem services. Moreover, western countries increasingly recognize macroalgae, traditionally cultivated in Asia, as targets for a new bio-economy that can be both economically profitable and environmentally sustainable. However, seagrass meadows and macroalgal forests are threatened by a variety of anthropogenic stressors. Most notably, rising temperatures and marine heatwaves are already devastating these ecosystems around the globe, and are likely to compromise profitability and production security of macroalgal farming in the near future. Recent studies show that seagrass and macroalgae can become less susceptible to heat events once they have been primed with heat stress. Priming is a common technique in crop agriculture in which plants acquire a stress memory that enhances performance under a second stress exposure. Molecular mechanisms underlying thermal priming are likely to include epigenetic mechanisms that switch state and permanently trigger stress-preventive genes after the first stress exposure. Priming may have considerable potential for both ecosystem restoration and macroalgae farming to immediately improve performance and stress resistance and, thus, to enhance restoration success and production security under environmental challenges. However, priming methodology cannot be simply transferred from terrestrial crops to marine macrophytes. We present first insights into the formation of stress memories in both seagrasses and macroalgae, and research gaps that need to be filled before priming can be established as new bio-engineering technique in these ecologically and economically important marine primary producers.

Improving restoration success through a precision restoration framework

Dryland ecosystems represent a significant portion of global land area, support billions of people, and suffer high rates of land degradation. Successfully restoring native vegetation to degraded drylands is a global priority and major challenge—highlighting the need for more efficient and successful restoration strategies. We introduce the concept of “precision restoration,” which targets critical biotic and abiotic barriers to restoration success and applies specific tools or methods based on barrier distribution in space and time. With an example from the sagebrush steppe biome, a North American cold desert, we present a framework for precision restoration in drylands that involves: (1) identifying site‐specific critical barriers to restoration success, (2) understanding the spatial and temporal variability of each barrier, and (3) applying the best available restoration strategies given the specific barrier and its variability, described in the first two steps. This framework aims to enhance restoration success by focusing restoration practices on ameliorating the influential barriers when and where they occur and away from applying singular landscape‐wide approaches.

Restoration-mediated alteration induces substantial structural changes, but negligible shifts in functional and phylogenetic diversity of a non-target community: a case study from a soda pan

Stream macroinvertebrates, as non-target organisms, may face with either a single or a complex stressor during a restoration treatment. We quantified the structural, phylogenetic, and functional responses to both single (water retention) and complex (water retention and grazing) stressors and analysed how the ecological quality changes, in order to reveal the potential unwanted consequences in a soda pan restoration. Species composition has been restructured and taxonomic diversity decreased significantly as a response to the complex stressor, while they did not change under the single stress. Neither the single nor the complex stressor influenced the phylogenetic diversity. Functional diversity showed mainly no or reversible changes. Changes in diversity metrics induced changes in Ecological Quality Ratios, but the ecological state decreased only under the complex stressor. Our results suggest that different facets of alpha diversity (taxonomic, functional and phylogenetic) are complementary and provide different information about community assembly against different stresses. We can support the opinion that taxon, phylogenetic and functional diversity are proper metrics in their own way to assess the impact of stress, but it is necessary to apply them together. Ecological knowledge of this paper could be considered throughout future conservation planning and enhance restoration success in aquatic environments.

Priority effects and competition by a native species inhibit an invasive species and may assist restoration.

Selecting native species for restoration is often done without proper ecological background, particularly with regard to how native and invasive species interact. Here, we provide insights suggesting that such information may greatly enhance restoration success. The performance of the native vine, Pueraria lobata, and that of the invasive bitter vine, Mikania micrantha, were investigated in South China to test how priority effects (timing and rate of germination and seedling growth) and competition (phytochemical effects and competitive ability) impact invasive plant performance. We found that, in the absence of competition, the germination rate of M. micrantha, but not of P. lobata, was significantly affected by light availability. P. lobata seedlings also performed better than those of M. micrantha during early growth phases. Under competition, negative phytochemical effects of P. lobata on M. micrantha were strong and we found M. micrantha to have lower performance when grown with P. lobata compared to when grown by itself. Relative interaction indexes indicated that, under interspecific competition, P. lobata negatively affected (i.e., inhibited) M. micrantha, whereas M. micrantha positively affected (i.e., facilitated) P. lobata. Higher photosynthetic efficiency and soil nutrient utilization put P. lobata at a further advantage over M. micrantha. Field trails corroborated these experimental findings, showing little recruitment of M. micrantha in previously invaded and cleared field plots that were sown with P. lobata. Thus, P. lobata is a promising candidate for ecological restoration and for reducing impacts of M. micrantha in China. This research illustrates that careful species selection may improve restoration outcomes, a finding that may also apply to other invaded ecosystems and species.

Facilitating Better Outcomes: How Positive Species Interactions Can Improve Oyster Reef Restoration

Over 85% of the world’s oyster reefs have been lost in the past two centuries, triggering a global effort to restore shellfish reef ecosystems and the ecosystem services they provide. While there has been considerable success in reestablishing oyster reefs, many challenges remain. These include: high incidence of failed restoration, high cost of restoration per unit area, and increasing stress from climate change, which now imperils many restored reefs. In order to leverage our past successes and progress the field, we must increase restoration efficiencies that not only reduce cost per unit area, but also increase the resilience of restored ecosystems. To address this need, we review the literature associated with the structure and function of oyster reef ecosystems to identify key positive species interactions (i.e. those species interactions where at least one partner benefits and no partners are harmed) that, if systematically incorporated into restoration planning, have the potential to greatly increase restoration outcomes and success. We classified positive inter- and intraspecific feedbacks between oysters and organisms associated with oyster ecosystems into the following seven functional categories: 1) physical reef creation, 2) positive density dependence, 3) refugia from physical stress, 4) refugia from biological stress, 5) biodiversity enhancement, 6) improvement of settlement, and 7) long-distance facilitation. We discuss each category of interaction positive feedback and how restoration practitioners can use knowledge of such processes to alter management and enhance restoration success. We propose that systematic incorporation of positive species interactions that generate these feedbacks into restoration practice may enhance ecological services provided by restored reefs and increase restoration success.

Playing to the Positives: Using Synergies to Enhance Kelp Forest Restoration

Kelp forests are highly productive foundation species along much of the world’s coastline. As a result, kelp are crucial to the ecological, social, and economic well-being of coastal communities. Yet, due to a combination of acute and chronic stressors, kelp forests are under threat and have declined in many locations worldwide. Active restoration of kelp ecosystems is an emerging field that aims to reverse these declines by mitigating negative stressors and then, if needed, introducing biotic material into the environment. To date, few restoration efforts have incorporated positive species interactions. This gap presents a potential shortcoming for the field as evidence from other marine ecosystems illustrates that the inclusion of positive species interactions can enhance restoration success. Additionally, as the climate continues to warm, this approach will be particularly pertinent as positive interactions can also expand the range of physical conditions under which species can persist. Here we highlight how practitioners can use positive density dependence within and amongst kelp species to increase the chances of restoration success. At higher trophic levels, we emphasize how co-restoring predators can prime ecosystems for restoration. We also investigate how emerging technologies in genetic and microbial selection and manipulation can increase the tolerance of target species to warming and other stressors. Finally, we provide examples of how we can use existing anthropogenic activities to facilitate restoration while performing alternative purposes. As kelp forests continue to decline and the field of kelp restoration continues to develop, it is also important that we monitor these potential advancements and ensure they do not have unintended ecosystem effects, particularly with untested techniques such as genetic and microbial manipulations. Nevertheless, incorporating positive species interactions into future restoration practice stands to promote a more holistic form of restoration that also increases the likelihood of success in a shifting seascape.

How Traditional Tribal Perspectives Influence Ecosystem Restoration

The hundreds of Indigenous tribes in the United States harbor diverse perspectives about the natural world, yet they share many views that are important for ecosystem restoration efforts. This paper features examples of how such views have guided ecosystem restoration through partnerships between tribal communities and the U.S. Forest Service in the western United States. Traditional perspectives have influenced restoration by deepening the understanding of reference conditions, expanding consideration of system dynamics, and guiding treatment based upon ethical principles and beliefs. More holistic perspectives may enhance restoration success by encouraging positive psychological and social effects that help sustain community efforts. Guided by traditional perspectives, restoration activities can reveal evidence of past human engagement with the land, which further illustrates the need and opportunity for restoration. Traditional perspectives can encourage more integrative, ethical, and self-reinforcing restoration that will benefit present-day tribal and non-tribal communities.

Positive Ecological Interactions and the Success of Seagrass Restoration

Seagrasses provide multiple ecosystem services including nursery habitat, improved water quality, coastal protection, and carbon sequestration. However, seagrasses are in crisis as global coverage is declining at an accelerating rate. With increased focus on ecological restoration as a conservation strategy, methods that enhance restoration success need to be explored. Decades of work in coastal plant ecosystems, including seagrasses, has shown that positive species relationships and feedbacks are critical for ecosystem stability, expansion, and recovery from disturbance. We reviewed the restoration literature on seagrasses and found few studies have tested for the beneficial effects of including positive species interactions in seagrass restoration designs. Here we review the full suite of positive species interactions that have been documented in seagrass ecosystems, where they occur, and how they might be integrated into seagrass restoration. The few studies in marine plant communities that have explicitly incorporated positive species interactions and feedbacks have found an increase in plant growth with little additional resource investment. As oceans continue to change and stressors become more prevalent, harnessing positive interactions between species through innovative approaches will likely become key to successful seagrass restoration.

Selection for genetics‐based architecture traits in a native cottonwood negatively affects invasive tamarisk in a restoration field trial

Climate change and competition from invasive species remain two important challenges in restoration. We examined the hypothesis that non‐native tamarisk (Tamarix spp.) reestablishment after aboveground removal is affected by genetics‐based architecture of native Fremont cottonwood (Populus fremontii) used in restoration. As cottonwood architecture (height, canopy width, number of stems, and trunk diameter) is, in part, determined by genetics, we predicted that trees from different provenances would exhibit different architecture, and mean annual maximum temperature transfer distance from the provenances would interact with the architecture to affect tamarisk. In a common garden in Chevelon, AZ, U.S.A. (elevation 1,496 m), with cottonwoods from provenances spanning its elevation distribution, we measured the performance of both cottonwoods and tamarisk. Several key findings emerged. On average, cottonwoods from higher elevations were (1) two times taller and wider, covered approximately 3.5 times more basal area, and were less shrubby in appearance, by exhibiting four times fewer number of stems than cottonwoods from lower elevations; (2) had 50% fewer tamarisk growing underneath, which were two times shorter and covered 6.5 times less basal area than tamarisk growing underneath cottonwoods of smaller stature; and (3) the number of cottonwood stems did not affect tamarisk growth, possibly because the negative relationship between cottonwood stems and basal area. In combination, these findings argue that cottonwood architecture is affected by local conditions that interact with genetics‐based architecture. These interactions can negatively affect the growth of reinvading tamarisk and enhance restoration success. Our study emphasizes the importance of incorporating genetic and environmental interactions of plants used in restoration.

Using trait‐based ecology to restore resilient ecosystems: historical conditions and the future of montane forests in western North America

AbstractHistorical reference conditions have provided empirical benchmarks for guiding ecological restoration but the relevance of historical conditions has been questioned in this era of rapid global change. Trait‐based ecology offers an alternative approach for setting restoration objectives. If we understand which phenotypic traits confer high survival in a given environment, then we can restore assemblages of species with favorable trait combinations to reduce mortality risk, achieve functional outcomes, and enhance restoration success. Our objective was to compare restoration prescriptions based on historical reference conditions versus trait‐based objectives in southwestern United States mixed conifer forests. To optimize survival and enhance resilience under projected increasing frequencies of fire and drought, we constructed and evaluated models based on combinations of three traits: thick bark, dense wood, and moderate leaf nitrogen concentration. Models with multiple traits accurately derived historical species abundance distributions, which is a necessary condition for the application of trait‐based models under less certain future conditions. Model results indicated that trait‐based restoration objectives could be achieved in two ways: by manipulating abundances of species that already coexist at a site or by adding native species from warmer climates to the local species pool. The latter approach may create no‐analog communities of native species. Restoration goals based on either historical reference conditions or future projections are special cases of a more general class of desired future conditions that are derived from trait‐based objectives. Functional ecology provides a general, flexible, and theory‐based approach to restoring resilient ecosystems at a time of rapid environmental change.