Restoration Trajectories Research Articles

Handheld Laser Scanning Detects Spatiotemporal Differences in the Development of Structural Traits among Species in Restoration Plantings

A major challenge in ecological restoration is assessing the success of restoration plantings in producing habitats that provide the desired ecosystem functions and services. Forest structural complexity and biomass accumulation are key measures used to monitor restoration success and are important factors determining animal habitat availability and carbon sequestration. Monitoring their development through time using traditional field measurements can be costly and impractical, particularly at the landscape-scale, which is a common requirement in ecological restoration. We explored the application of proximal sensing technology as an alternative to traditional field surveys to capture the development of key forest structural traits in a restoration planting in the Midlands of Tasmania, Australia. We report the use of a hand-held laser scanner (ZEB1) to measure annual changes in structural traits at the tree-level, in a mixed species common-garden experiment from seven- to nine-years after planting. Using very dense point clouds, we derived estimates of multiple structural traits, including above ground biomass, tree height, stem diameter, crown dimensions, and crown properties. We detected annual increases in most LiDAR-derived traits, with individual crowns becoming increasingly interconnected. Time by species interaction were detected, and were associated with differences in productivity between species. We show the potential for remote sensing technology to monitor temporal changes in forest structural traits, as well as to provide base-line measures from which to assess the restoration trajectory towards a desired state.

Top 10 indicators for evaluating restoration trajectories in the Brazilian Atlantic Forest

Considering that ecosystem restoration is a long-term process, the evaluation of each stage of its trajectory may allow us to predict the success of the restoration goals. Given that there are plenty of indicators in the scientific literature for measuring restoration success, and there are stakeholders which are the key actors of restoration, our aim was to determine a common and simple set of indicators ranked by stakeholders for evaluating the restoration trajectory. We selected 52 indicators for monitoring high-diversity forest restoration projects in the Brazilian Atlantic Forest and organized them into six categories: (1) physical and structural, (2) composition/biodiversity, (3) environmental services, (4) ecological processes, (5) economic and (6) social. We sent questionnaires to stakeholders from five Brazilian states, who evaluated these indicators (with rates ranging from 0 to 3, where 0 = not important or should not be considered; 1 = low importance; 2 = important; and 3 = very important, considering four time-stages throughout the process (2–3, 3–10, 10–50 and > 50 years). Based on this assessment, we ranked the indicators and tested whether the importance of the categories changed between them and over time. We present the “top ten” indicators (with the ten highest grades) for each stage, selected, and ranked by practitioners, that can be used to evaluate restoration projects and provide guidance for restoration policies. In the initial stage, from 2 to 3 years, social attributes were highly important, related to the degree of acceptance by the community. Economic indicators were also important at the initial stage, when the costs of developing, deploying, and maintaining restoration actions are high. Physical and structural indicators were more important in the short-term stage, from 3 to 10 years. Ecological indicators related to composition/biodiversity and ecological processes became relevant after 3 years and kept so onwards. Only in the long-term, addressing ecosystem services became an important indicator of the restoration success, to stakeholders. Overall, stakeholders care for forest structure and establishment of plants in all stages, while composition/biodiversity and richness gain importance in more advanced phases of restoration trajectory.

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.

A biome-wide experiment to assess the effects of propagule size and treatment on the survival of Portulacaria afra (spekboom) truncheons planted to restore degraded subtropical thicket of South Africa.

Insights from biome-wide experiments can improve efficacy of landscape-scale ecological restoration projects. Such insights enable implementers to set temporal and geographical benchmarks and to identify key drivers of success during the often decades-long restoration trajectory. Here we report on a biome-wide experiment aimed at informing the ecological restoration of thousands of hectares of degraded subtropical thicket dominated by the succulent shrub, Portulacaria afra (spekboom). Restoration using spekboom truncheons has the potential to sequester, for a semi-arid region, large amounts of ecosystem carbon, while regenerating a host of associated ecosystem services. This study evaluates, after about three years post-propagation, the effects of spekboom truncheon size and treatment on survivorship in 40 fence-enclosed (0.25 ha) plots located in target habitat across the entire spekboom thicket biome. In each plot, locally harvested spekboom truncheons, comprising eight size/treatment combinations, were planted in replicated rows of between 24 and 49 individuals, depending on treatment. The experiment assessed the role of truncheon size, spacing, application of rooting hormone and watering at planting on survivorship percentage as an indicator of restoration success. All eight combinations recorded extreme minimum survivorship values of zero, while the range of extreme maximum values was 70-100%. Larger truncheons (>22.5 mm diameter) had almost double the survivorship (ca. 45%) than smaller truncheons (< 15 mm) (ca. 25%). Planting large, untreated truncheons at 1 m intervals-as opposed to 2 m intervals recommended in the current restoration protocol-resulted in no significant change in survivorship. The application of rooting hormone and water at planting had no significant effect on restoration success for both large and small truncheons. While our results do not provide an evidence base for changing the current spekboom planting protocol, we recommend research on the financial and economic costs and benefits of different propagation strategies in real-world contexts.

Measuring savanna woody cover at scale to inform ecosystem restoration

AbstractThe maturity of remote sensing and ecosystem restoration science provides new opportunities to monitor and assess ecosystem indicators at finer resolutions and at suitable scales. A key link in joining these fields is creating a framework to apply these rich datasets to ecosystem restoration projects. Savanna woodland ecosystems have discontinuous tree cover that is an important, but potentially highly variable, structural component of these ecosystems. Woody cover in savannas is also well suited to being measured with remote sensing techniques. We extracted woody cover from a 66‐yr time series of aerial imagery covering 1718 ha of mesic savanna ecosystem in northern Australia, adjacent to the Ranger uranium mine and encompassing portions of Kakadu National Park. This ecosystem is proposed as a reference ecosystem that may be used to comparatively assess and monitor restoration trajectories of the mine site in the coming decades. The spatiotemporal patterns of change in woody cover were assessed at spatial extents similar to the mine site. We were able to construct a robust distribution of canopy cover values and associated spatial heterogeneity that can be used to set closure criteria, inform restoration trajectories, and guide monitoring activities for the restored mine site.

Drivers of Restoration Trajectory of a Community of Regenerant Plants: Natural Regeneration or Tree Seedling?

Tree plantation is the most used technique for ecological restoration, although passive restoration requires a lower investment of resources. This research aimed to compare the composition and structure of the community of regenerant plants in areas under restoration through Assisted Natural Regeneration and mixed native Tree Planting, in the same area. We randomly placed 12 plots of 100 m2 each and sampled all the regenerating individuals found within them. We compared both restoration methods regarding growth pattern, dispersal syndromes, and successional groups. In both methodologies, trees and shrubs were the most abundant growth forms. The pioneer successional class was the most abundant in number of individuals for both treatments. We concluded that the two restoration methods allowed the regeneration of native species. We propose that Assisted Natural Regeneration is a viable restoration strategy, capable of boosting the initial processes of the community, especially in a matrix surrounded by remaining forests.

Risk-based assessment of the post-earthquake functional disruption and restoration of distributed infrastructure systems

A risk-based framework for assessing the post-earthquake functional loss and restoration of distributed infrastructure systems is presented. Using an appropriate seismic source model, a stochastic earthquake catalogue is generated for the target region. For each event in the catalogue, the joint distribution of shaking and component-level damage maps are produced. Process-based discrete event simulation is coupled with an appropriate method for linking physical damage to functional impacts to model the restoration for each damage map. By considering all possible events that are impactful to the target region and their associated rates of occurrence, the full probability distribution of the functional recovery trajectory of the system is obtained. Dispersion disaggregation is used to isolate the individual contribution of each random variable to the uncertainty bounds in the restoration trajectory. A case study involving the city of Napa's water system is used to demonstrate how the framework can support resilience-based risk-informed decision-making for distributed infrastructure.

Examining assumptions of soil microbial ecology in the monitoring of ecological restoration

Abstract1. Global interest in building healthy soils combined with new DNA sequencing technologies has led to the generation of a vast amount of soil microbial community (SMC) data.2. SMC analysis is being adopted widely for monitoring ecological restoration trajectories. However, despite the large and growing quantity of soil microbial data, it remains unclear how these data inform and best guide restoration practice.3. Here, we examine assumptions around SMC as a tool for guiding ecosystem restoration and evaluate the effectiveness of using species inventories of SMC as a benchmark for restoration success.4. We investigate other approaches of assessing soil health, and conclude that we can significantly enhance the utility of species inventory data for ecological restoration by complementing it with the use of non‐molecular approaches.

Short-term impact of sediment addition on plants and invertebrates in a southern California salt marsh.

The implementation and monitoring of management strategies is integral to protect coastal marshes from increased inundation and submergence under sea-level rise. Sediment addition is one such strategy in which sediment is added to marshes to raise relative elevations, decrease tidal inundation, and enhance ecosystem processes. This study looked at the plant and invertebrate community responses over 12 months following a sediment addition project on a salt marsh located in an urbanized estuary in southern California, USA. This salt marsh is experiencing local subsidence, is sediment-limited from landscape modifications, has resident protected species, and is at-risk of submergence from sea-level rise. Abiotic measurements, invertebrate cores, and plant parameters were analyzed before and after sediment application in a before-after-control-impact (BACI) design. Immediately following the sediment application, plant cover and invertebrate abundance decreased significantly, with smothering of existing vegetation communities without regrowth, presumably creating resulting harsh abiotic conditions. At six months after the sediment application treatment, Salicornia bigelovii minimally colonized the sediment application area, and Spartina foliosa spread vegetatively from the edges of the marsh; however, at 12 months following sediment application overall plant recovery was still minimal. Community composition of infaunal invertebrates shifted from a dominance of marsh-associated groups like oligochaetes and polychaetes to more terrestrial and more mobile dispersers like insect larvae. In contrast to other studies, such as those with high organic deposition, that showed vegetation and invertebrate community recovery within one year of sediment application, our results indicated a much slower recovery following a sediment addition of 32 cm which resulted in a supratidal elevation with an average of 1.62 m (NAVD88) at our sampling locations. Our results indicate that the site did not recover after one year and that recovery may take longer which illustrates the importance of long-term monitoring to fully understand restoration trajectories and inform adaptive management. Testing and monitoring sea-level rise adaptation strategies like sediment addition for salt marshes is important to prevent the loss of important coastal ecosystems.

Soil phosphorus dynamics along a short‐term ecological restoration trajectory of a coastal sandplain forest in New Zealand

AbstractWe aim to understand the impact of ecological restoration on soil biogeochemistry, and the interrelationship between vegetation and soil phosphorus. In a study of two different‐aged soils in coastal New Zealand, soils are described along a transition from abandoned agricultural pasture, through 6‐year old restoration plots, towards forest fragments that have been largely undisturbed for 75 and 166 years. Soil biogeochemistry varied spatially along this restoration trajectory; there were profound changes in surface soil, but little impact on deeper soil horizons. In the early stages, soil organic matter accumulation and decomposition, and increasing demand of N from fast‐growing plants corresponded with rapid nutrient mineralization. Loss of soil total P, an increase of occluded P, and the increasing importance of soil organic P as soils weathered and aged, supported conceptual models of longer‐term soil pedogenesis. There was no evidence that the success of the establishment of plants varied across the site, but this is a first report of vegetation establishment during ecological restoration markedly impacting soil P dynamics and biogeochemistry.

Inducing seed dispersal by generalist frugivores: A new technique to overcome dispersal limitation in restoration

Abstract Dispersal limitation severely impairs the trajectory of restoration, mainly due to the lack of seed vectors bringing seeds from nearby habitats; a role played by many frugivorous vertebrates that can be absent or reduced in restored or degraded sites. Here we propose a new technique named Induced Seed Dispersal, that amplifies the role that many generalist frugivores have in seed dispersal. It consists in the offering of seeds embedded in the pulp of commercial fruits or whole native fleshy fruits in feeders to generalist frugivores, which ingest the seeds and defecate them elsewhere. We set feeders in a restored site and monitored the visiting pattern of these frugivores with cameras‐traps. We also set seed traps to retrieve seeds dispersed by frugivores and offered around 1,500 seeds of Cecropia hololeuca (Urticaceae) per week for 1 year. We recorded at least 24 generalist frugivore species of terrestrial mammals, bats and birds, which ingested/removed the seeds/fruits from the feeders. Seeds of C. hololeuca dispersed by marmosets were retrieved in the seed traps and germinated. We estimated a potential seed rain of more than 600 C. hololeuca seeds ha−1 mo−1. Synthesis and applications. Our study demonstrates that this new technique can make use of generalist frugivores to assist restoration or regeneration into sites where seed dispersal is compromised by the lack of dispersers or limited seed arrival. Inducing seed dispersal by generalist frugivores is a low‐cost and easy‐managed technique that can be applied year‐round in restoration and forest enrichments at all scales.

Gain in biodiversity but not in phytostabilization after 3 years of ecological restoration of contaminated Mediterranean soils

Recent studies consider the native flora as a potential source of plant candidates for phytostabilization of metal and metalloid (MM) contaminated soils, but ecological restoration is not the main objective of these researches. However, in contaminated areas, phytostabilization should be considered as a useful tool for ecological restoration. The present study takes stock of 3 years of a Mediterranean pilot site implementation using native plant species to recover plant and microbial communities (diversity and functions) together with soil remediation in the Calanques National Park. To determine the success of this operation, three in situ treatments were compared: ecological restoration plots characterized by the handling of physical environment (creation of cultivation terraces) and plants, negative control plots without vegetation but with the same physical environment handling as ecological restoration plots, and positive control plots with natural vegetation and no handling. The results suggest that an ecological restoration trajectory is initiated in the ecological restoration plots, characterized by a partial permanent plant cover. However, there is no evidence of a significant improvement of soil quality (evaluated by soil texture, pH, nutrients and organic carbon contents, cation exchange capacity, microbial biomass and activities) and phytostabilization efficiency after 3 years. Native plant communities and their associated microorganisms may need more time before improving soil quality and MM stabilization under the drastic Mediterranean conditions. Any amendment addition to accelerate restoration and MM immobilization was forbidden in this protected area. Under such conditions, an active restoration need to be carried out in this contaminated area even if resilient dynamics of the native plant communities may sporadically occur over a long period of time.

Functional Trait-Based Screening of Zn-Pb Tolerant Wild Plant Species at an Abandoned Mine Site in Gard (France) for Rehabilitation of Mediterranean Metal-Contaminated Soils.

The selection of plant species at mine sites is mostly based on metal content in plant parts. Recent works have proposed referring to certain ecological aspects. However, plant traits for plant metal-tolerance still need to be accurately assessed in the field. An abandoned Zn-Pb mine site in Gard (France) offered the opportunity to test a set of ecological criteria. The diversity of micro-habitats was first recorded through floristic relevés and selected categorical and measured plant traits were compared for plant species selection. The floristic composition of the study site consisted in 61 plant species from 31 plant families. This approach enabled us to focus on seven wild plant species naturally growing at the mining site. Their ability to form root symbioses was then observed with a view to phytostabilization management. Four species were considered for phytoextraction: Noccaea caerulescens (J. et C. Presl) FK Meyer, Biscutella laevigata L., Armeria arenaria (Pers.) Schult. and Plantago lanceolata L. The metal content of their aerial and root parts was then determined and compared with that of soil samples collected at the same site. This general approach may lead to the development of a knowledge base for assessment of the ecological restoration trajectory of the site and can help in plant selection for remediation of other metal-rich soils in the Mediterranean area based not only on metal removal but on ecological restoration principles.

CONSIDERATIONS ON THE JOINT RECOVERY OF THE MONUMENT AND ITS ENVIRONMENT: THE TOWN WALLS OF ALBARRACÍN (SPAIN)

Abstract. The city walls of Albarracín (Teruel) show an exemplary trajectory of restoration and conservation works, thanks to a fifty year-long trajectory of interventions carried out by different architects. The last of these projects, promoted by the City Council and driven by Fundación Santa María de Albarracín, was drafted in 2019 and involved the restoration of the southern end of the wall. For the first time, this project has addressed the recovery of the monument and its surroundings in a joint effort that bets on a global vision for the city’s public space system. The keys to this binomial are based on the following premises: a well-coordinated monument-environment relationship, the emphasis on a conservative approach to the restoration works, the promotion of public use and the dignification of the space in a coherent way with its context. The joint treatment of the building and its environment goes far beyond an aesthetic or functional issue – which may have been achieved through independent projects – and verifies the criteria adopted for both dimensions of the project: minimal intervention, distinguishability, preservation of the authenticity, reversibility, compatibility, character, readability and sustainability. In general, this approach reduces the risks of unilateral, partial or limiting visions ending in the loss of heritage value and embraces the understanding of the immediate environment as an inseparable extension of the monument itself.

Framework Species Approach Proves Robust in Restoring Forest on Fire Prone Invasive Grass: A Case Study from Panama

ABSTRACT Grasses and fire pose a major challenge for forest restoration. Here we evaluate a case study of reforestation in an area invaded by the tall invasive grass Saccharum spontaneum in the Panama Canal Watershed. The project objectives were to (1) replace Saccharum with a forest, (2) restore a stratified mixed species forest and (3) sequester carbon. We aimed to compare the practice of forest restoration with a treatment grounded in theory. Therefore, the first species selection method followed business-as-usual: contractors planted any combination of 130 prescribed species. The second method followed the framework species approach, a mixture of 22 species was planted to ensure early shade, create a stratified forest over time, attract seed dispersers, and for their potential to fix N2. Both treatments showed successful restoration trajectories 8.5 years after planting, they did not differ in structural characteristics (stem density, basal area, aboveground biomass, height, and amount of Saccharum). However, based on the species present, the framework approach shows more potential to become a stratified forest. As the framework approach also withstood fires much better than the business-as-usual approach, we conclude that it improves restoration success in this human-dominated landscape.

Functional traits of tree saplings and adults in a tropical cloud forest restoration context

Background: The use of tree species’ functional traits is a promising approach in forest restoration. However, some traits may change during ontogeny.&#x0D; Questions: Does intraspecific variation in functional traits occur between sapling and adult stages? Do groups of species can be delimited based on functional traits regardless of their ontogenetic stage?&#x0D; Study sites and dates: Cloud forest restoration, Veracruz, Mexico, 2016.&#x0D; Methods: Saplings and adults of eight native tree species in different age plantations were measured for leaf area (LA), specific leaf area (SLA), stomatal density (SD), foliar nutrient content (C, N, P) and relative growth rate (RGR). Wood density (WD) was measured for adults. Data were analyzed using linear mixed models and principal component analysis (PCA).&#x0D; Results: Overall, SLA was higher in saplings than in adults. A few species showed intraspecific variation for LA (three species), SD (three) and foliar N content (one). Species with high WD ( Quercus spp . ) and intermediate WD ( e.g . Liquidambar styraciflua ) tended to have lower LA and SLA, and higher SD. Species with low WD ( e.g . Heliocarpus donnellsmithii) had high SLA, RGR, and N content. PCA highlighted that saplings and adults of a same species were close to each other within the ordination space. &#x0D; Conclusions: Intraspecific variation between saplings and adults was small for most traits (except SLA) in comparison to differences across species. Therefore species trait values (measured in individuals of any age) could be a useful tool to characterize groups of species during the forest restoration trajectory.

Predicting the likelihood of a desirable ecological regime shift: A case study in Cootes Paradise marsh, Lake Ontario, Ontario, Canada

Abstract Environmental modelling is one of the pillars of the management process, representing an “information integrator” that brings together scientists, managers, and other stakeholders in a joint assessment of our understanding of the system being managed and the compelling knowledge gaps we seek to answer through monitoring and research. The overarching goal of the present modelling study is to offer insights into the restoration and management of Cootes Paradise marsh, one of the most degraded shallow wetlands in Southern Ontario. We use a mechanistic model to leverage our understanding of the major phosphorus biogeochemical pathways in Cootes Paradise. We also develop a network of statistical models that accommodates the spatial heterogeneity of the prevailing water quality conditions in the marsh. Combining the insights from both models, we found that a drastic reduction of point- and nonpoint-source nutrient loading could trigger a non-linear shift from the current turbid-phytoplankton dominated state to a clear-macrophyte dominated state. The restoration trajectory of the system can be profoundly modulated by the presence of a thriving macrophyte community with an enhanced ability to sequester phosphorus (i.e., the net amount of phosphorus taken up per unit of plant tissue). Critical remedial actions to re-establish the targeted macrophyte species in their native marsh habitats include both the intensification of local planting efforts and the control of invasive plant species. Another important finding of our modelling analysis is that the signature of the water quality improvements brought about by nutrient loading reductions dissipates as we move from the marsh’s western end to the central area due the presence of confounding factors, such as the hydraulic loading from Spencer Creek, internal nutrient loading, wind resuspension, and bioturbation. Given the high uncertainties associated with forecasting drastic (and costly) remedial actions, we argue in favour of a socioeconomic assessment of Cootes Paradise marsh as an ecosystem service provider to determine the benefits in terms of monetary values when we examine different courses of management options.

Short-Term Stream and Riparian Responses to Beaver Dam Analogs on a Low-Gradient Channel Lacking Woody Riparian Vegetation

As ecosystem engineers, beavers (Castor canadensis) influence biogeomorphology and riparian vegetation. Streams with historic beaver removal and grazing often become incised, thereby altering stream and riparian processes. Anthropogenic structures that mimic beaver dams called beaver dam analogs (BDAs) may reverse incision by reintroducing historic processes. To understand BDAs as a process-based restoration tool, monitoring is needed across a range of watershed and stream conditions, but monitoring lags behind implementation. We constructed five BDAs in Central Oregon, on a low-gradient stream to test whether it may transport sufficient sediment to favor streambed aggradation behind BDAs. The stream also lacks woody riparian vegetation, and we examined how water temperatures and restoration plantings respond to BDAs where woody riparian vegetation is absent. We monitored structure integrity, aggradation, water temperature, groundwater, and vegetation for 1–2 yr after structures were installed. BDAs retained flows equally whether they were constructed from on-site juniper or off-site willow. During high flows, three structures failed and were rebuilt using improved design. After one year, aggradation of sediment above the two structures that survived flooding was negligible at one structure and high (33.7 m3) at the other. Groundwater levels rose 18–30 cm up to 135 m upstream of BDAs and 12 m into the floodplain. We found no evidence that BDAs raised stream temperatures. Within six months, willow cuttings planted near BDAs exhibited 1.3 times more growth than those on unimpounded locations. Overall, BDAs promoted a restoration trajectory on a low-gradient stream lacking woody riparian vegetation.

Macroinfauna responses and recovery trajectories after an oil spill differ from those following saltmarsh restoration

Given the severity of injuries to biota in coastal wetlands from the Deepwater Horizon oil spill (DWH) and the resulting availability of funding for restoration, information on impacted salt marshes and biotic development of restored marshes may both help inform marsh restoration planning in the near term and for future spills. Accordingly, we performed a meta-analysis to model a restoration trajectory of total macroinfauna density in constructed marshes (studied for ~30 y), and with a previously published restoration trajectory for amphipods, we compared these to recovery curves for total macroinfauna and amphipods from DWH impacted marshes (over 8.5 y). Total macroinfauna and amphipod densities in constructed marshes did not consistently reach equivalency with reference sites before 20 y, yet in heavily oiled marshes recovery occurred by 4.5 y post spill (although it is unlikely that macroinfaunal community composition fully recovered). These differences were probably due to initial conditions (e.g., higher initial levels of belowground organic matter in oiled marshes) that were more conducive to recovery as compared to constructed marshes. Furthermore, we found that amphipod trajectories were distinctly different in constructed and oiled marshes as densities at oiled sites exceeded that of reference sites by as much as 20x during much of the recovery period. Amphipods may have responded to the rapid increase and high biomass of benthic microalgae following the spill. These results indicate that biotic responses after an oil spill may be quantitatively different than those following restoration, even for heavily oiled marshes that were initially denuded of vegetation. Our dual trajectories for oil spill recovery and restoration development for macroinfauna should help guide restoration planning and assessment following the DWH as well as for restoration scaling for future spills.

Depth Affects Seagrass Restoration Success and Resilience to Marine Heat Wave Disturbance

Accelerating losses of seagrass meadows motivate the restoration of these highly productive and beneficial ecosystems. Understanding how environmental parameters including depth and temperature affect restoration trajectories through time is key to conserving and restoring seagrass meadows. We used a long-term (12-year), landscape-scale experiment to test the effect of depth on eelgrass (Zostera marina) restoration success and resilience to a marine heat wave (MHW) disturbance. We found that depth was a critical determinant of seagrass restoration success, with no long-term success at sites deeper than 1.5 m below mean sea level (MSL) or shallower than − 0.8 m MSL. Seeds germinated below − 1.5 m MSL, but shoots did not persist, confirming earlier predictions from a hydrodynamic-vegetation model. Depth was also a significant predictor of seagrass resilience following MHW disturbance. Our results suggest that areas of restored seagrass that are resilient to temperature stress exist across an intermediate depth range, excluding the shallowest and deepest portions of the full habitable depth range for restored seagrass. Over the next decades, sea-level rise will likely affect both the habitable area and the resilient area, available for seagrass restoration. However, seagrass enhancement of sediment accretion may at least partially offset sea-level rise rates. As ocean temperatures warm and MHWs occur more frequently, the resilience of seagrass meadows to temperature stress will be of increasing concern. These results suggest that depth is a critical parameter that will help determine what areas are most resilient and therefore most suitable for conservation and restoration.