Improve Restoration Outcomes Research Articles

Biochar soil amendments in prairie restorations do not interfere with benefits from inoculation with native arbuscular mycorrhizal fungi

Little of the historical extent of tallgrass prairie ecosystems remains in North America, and therefore there is strong interest in restoring prairies. However, slow‐growing prairie plants are initially weak competitors with the fast‐growing yet short‐lived weedy plant species that are typically abundant in recently established prairie restorations. One way to aid establishment of slow‐growing plant species is through adding soil amendments to prairie restorations before planting. Arbuscular mycorrhizal (AM) fungi form mutualisms with the roots of most terrestrial plants and are particularly important for the growth of slow‐growing prairie plant species. As prairie ecosystems are adapted to fires that leave biochar (charred organic material) in the soil, adding biochar as well as AM fungal strains from undisturbed remnant prairies into the soil of prairie restorations may improve restoration outcomes. Here, we test this prediction during the first four growing seasons of a prairie restoration. When prairie plant seedlings were inoculated prior to planting into the field with AM fungi derived from remnant prairies, that one‐time inoculation significantly increased growth of five of the nine tested plant species through at least two growing seasons. This long‐term benefit of AM fungal inoculation was unaffected by biochar addition to the soil. Biochar application rates of at least 10 tons/ha significantly decreased Coreopsis tripteris growth but acted synergistically with AM fungal inoculation to significantly improve survival of Schizachyrium scoparium. Overall, inoculation with native AM fungi can help promote prairie plant establishment, but concomitant use of biochar soil amendments had relatively little effect.

Biodiversity responses to land‐use and restoration in a global biodiversity hotspot: Ant communities in Brazilian Cerrado

AbstractGiven that land‐use change is the main cause of global biodiversity decline, there is widespread interest in adopting land‐use practices that maintain high levels of biodiversity, and in restoring degraded land that previously had high biodiversity value. In this study, we use ant taxonomic and functional diversity to examine the effects of different land uses (agriculture, pastoralism, silviculture and conservation) and restoration practices on Cerrado (Brazilian savanna) biodiversity. We also examine the extent to which ant diversity and composition can be explained by vegetation attributes that apply across the full land management spectrum. We surveyed vegetation attributes and ant communities in five replicate plots of each of 13 land‐use and restoration treatments, including two types of native vegetation as reference sites: cerrado sensu stricto and cerradão. Several land‐use and restoration treatments had comparable plot richness to that of the native reference habitats. Ant species and functional composition varied systematically among land‐use treatments following a gradient from open habitats such as agricultural fields to forested sites. Tree basal area and grass cover were the strongest predictors of ant species richness. Losses in ant diversity were higher in land‐use systems that transform vegetation structure. Among productive systems, therefore, uncleared pastures and old pine plantations had similar species composition to that occurring in cerrado sensu stricto. Restoration techniques currently applied to sites that were previously Cerrado have focused on returning tree cover, and have failed to restore ant communities typical of savanna. To improve restoration outcomes for Cerrado biodiversity, greater attention needs to be paid to the re‐establishment and maintenance of the grass layer, which requires frequent fire. At the broader scale, conservation planning in agricultural landscapes, should recognize the value of land‐use mosaics and the risks of homogenization.

Reintroduction of freshwater macroinvertebrates: challenges and opportunities.

Species reintroductions-the translocation of individuals to areas in which a species has been extirpated with the aim of re-establishing a self-sustaining population-have become a widespread practice in conservation biology. Reintroduction projects have tended to focus on terrestrial vertebrates and, to a lesser extent, fishes. Much less effort has been devoted to the reintroduction of invertebrates into restored freshwater habitats. Yet, reintroductions may improve restoration outcomes in regions where impoverished regional species pools limit the self-recolonisation of restored freshwaters. We review the available literature on macroinvertebrate reintroductions, focusing on identifying the intrinsic and extrinsic factors that determine their success or failure. Our study reveals that freshwater macroinvertebrate reintroductions remain rare, are often published in the grey literature and, of the attempts made, approximately one-third fail. We identify life-cycle complexity and remaining stressors as the two factors most likely to affect reintroduction success, illustrating the unique challenges of freshwater macroinvertebrate reintroductions. Consideration of these factors by managers during the planning process and proper documentation-even if a project fails-may increase the likelihood of successful outcomes in future reintroduction attempts of freshwater macroinvertebrates.

Collaborative restoration effects on forest structure in ponderosa pine-dominated forests of Colorado

In response to large, severe wildfires in historically fire-adapted forests in the western US, policy initiatives, such as the USDA Forest Service’s Collaborative Forest Landscape Restoration Program (CFLRP), seek to increase the pace and scale of ecological restoration. One required component of this program is collaborative adaptive management, in which monitoring data are used to iteratively evaluate and improve future management actions. Here, we assess the success of seven CFLRP treatments, implemented on 2,300 ha during the first three years of the Colorado Front Range Landscape Restoration Initiative (LRI) at achieving desired forest structure by comparing pre- and post-treatment conditions. We also compare post-treatment conditions with reconstructions of historical (ca. 1860) forest conditions to contextualize the magnitude of treatment effects. Restoration projects moved stands toward desired conditions by reducing basal area, tree density, and canopy cover and increasing average tree diameter, large gap cover, and abundance of small- to medium-sized tree groups. Post-treatment stands were similar to historical stands with respect to basal area of ponderosa pine; however, they had higher total tree density and fewer gaps than historical reference conditions, suggesting that restoration prescriptions may be improved with increased flexibility for density reduction of Douglas-fir and increased gap creation. This examination of early CFLRP treatment outcomes as they relate to desired conditions informs potential areas of adjustments to future treatments and provides baseline data to evaluate the evolution of treatments over the program’s lifespan. We also identify and discuss several scientific, social, and logistical constraints to large-scale restoration success and make several recommendations to improve restoration outcomes.

Networked and embedded scientific experiments will improve restoration outcomes

Vast areas of degraded land have proliferated worldwide. In response to this transformation, ambitious targets have been set to restore degraded ecosystems, such as the the Bonn Challenge, which aims to restore 350 million ha of forestland by 2030. Achieving such goals will require a larger evidence base of restoration studies, which could be realized by systematically embedding scientific experiments within restoration programs. We examine the feasibility of this strategy with examples of successful transdisciplinary research involving embedded experiments in associated fields, and recommend that such field sites be linked to create a global network of embedded experiments. To unify a networked approach, we call on restoration stakeholders to develop acceptable industry standards of experimental design. Finally, we suggest how to use this strategy effectively to meet the biome‐scale challenges of the coming decades.

Re-establishment of Protea repens after clearing invasive Acacia saligna: Consequences of soil legacy effects and a native nitrophilic weedy species

Invasive Australian acacias can alter soil chemistry and microbial communities in areas they invade. After clearing invasive acacias, these changes can persist, and previously invaded areas can become dominated by nitrophilic weedy species. Restoration of viable native plant communities in cleared sites often fails due to a lack of native species re-establishment. Therefore, to improve restoration outcomes, it is important to understand the effects of soil chemical and biotic legacies, and of nitrophilic weedy species, on native species re-establishment. To investigate the effect of soil chemical legacies, we germinated and grew Protea repens seedlings (a native proteoid shrub) as an indicator species in soil taken from areas cleared of Acacia saligna in lowland fynbos, as well as from non-invaded areas under controlled conditions. To investigate the effect of soil biotic legacies, we sterilized half the soil from each cleared or non-invaded area. We grew Ehrharta calycina (a native nitrophilic weedy grass species) in half of each treatment and measured the effect of treatments on P. repens germination and growth. Germination percentage, root and shoot dry mass of P. repens did not significantly differ between altered and native soil chemistry. The germination percentage of P. repens was significantly greater (93%) in the presence of soil microbial communities than in their absence. The presence of E. calycina significantly increased (29%) the root-to-shoot ratio of P. repens than their absence. Since the legacy of altered soil chemistry did not have a direct negative effect on P. repens germination and growth; we conclude that restoration efforts do not always have to manage altered soil chemistry after clearing invasive A. saligna.

Barriers to ecosystem restoration presented by soil legacy effects of invasive alien N2‐fixing woody species: implications for ecological restoration

Impacts of invasive alien N2‐fixing woody species and how they can persist as soil legacy effects after invasive species control are well appreciated, but how soil legacy effects can present barriers to restoration is poorly understood. Finding better ways to deal with these barriers to restoration is essential to improving restoration outcomes. In this study, we review 440 studies to identify barriers to restoration and potential management actions for the barriers to restoration, and provide practical application examples of the management actions. Our findings suggest that altered soil microbial communities, depleted native soil seed banks, elevated N status, secondary invasion and weedy native species dominance, and reinvasion are potential barriers to restoration. Furthermore, carbon addition, litter removal, soil microbial treatments, establishing species adapted to low N levels, prescribed burning, classical biological control, grazing, mowing, herbicide or graminicide application, manual weeding, soil N management, soil solarization, weed mats, native species reintroduction, and nurse plants are potential management actions for these barriers to restoration. However, there is little evidence suggesting that several of these barriers to restoration hinder improved restoration outcomes and this could be due to little research on them. More research is needed to assess their relative importance in hindering improved restoration outcomes. Management actions are rarely applied in combination, despite that they often address distinct barriers to restoration. Management actions should be combined into an integrated management effort to improve restoration outcomes.

Is saltmarsh restoration success constrained by matching natural environments or altered succession? A test using niche models.

Restored habitats, such as saltmarsh created through managed realignment, sometimes fail to meet targets for biological equivalence with natural reference sites. Understanding why this happens is important in order to improve restoration outcomes.Elevation in the tidal frame and sediment redox potential are major controls on the distribution of saltmarsh plants. We use niche models to characterize 10 species’ responses to these, and test whether differences in species occurrence between restored and natural saltmarshes in the UK result from failure to recreate adequate environmental conditions.Six species occurred less frequently in recently restored marshes than natural marshes. Failure of restored marshes to achieve the elevation and redox conditions of natural marshes partially explained the underrepresentation of five of these species, but did not explain patterns of occurrence on older (>50 years) restored marshes.For all species, an effect of marsh age remained after controlling for differences in environmental conditions. This could be due to differences in successional mechanism between restored and natural marshes. In recently restored marshes, high‐marsh species occurred lower in the tidal frame and low‐marsh species occurred higher in the tidal frame than in natural marshes. This supports the hypothesis that competition is initially weaker in restored marshes, because of the availability of bare sediment across the whole tidal frame. Species that establish outside their normal realized niche, such as Atriplex portulacoides, may inhibit subsequent colonization of other species that occurred less frequently than expected on older restored marshes. Synthesis and applications. Niche models can be used to test whether abiotic differences between restored sites and their natural counterparts are responsible for discrepancies in species occurrence. In saltmarshes, simply replicating environmental conditions will not result in equivalent species occurrence.

Living on the Edge: Increasing Patch Size Enhances the Resilience and Community Development of a Restored Salt Marsh

Foundation species regulate communities by reducing environmental stress and providing habitat for other species. Successful restoration of biogenic habitats often depends on restoring foundation species at appropriate spatial scales within a suitable range of environmental conditions. An improved understanding of the relationship between restoration scale and environmental conditions has the potential to improve restoration outcomes for many biogenic habitats. Here, we identified and tested whether inundation/exposure stress and spatial scale (patch size) can interactively determine (1) survival and growth of a foundation species, Spartina alterniflora and (2) recruitment of supported fauna. We planted S. alterniflora and artificial mimics in large and small patches at elevations above and below local mean sea level (LMSL) and monitored plant survivorship and production, as well as faunal recruitment. In the first growing season, S. alterniflora plant survivorship and stem densities were greater above LMSL than below LMSL regardless of patch size, while stem height was greatest in small patches below LMSL. By the third growing season, S. alterniflora patch expansion was greater above LMSL than below LMSL, while stem densities were higher in large patches than small patches, regardless of location relative to LMSL. Unlike S. alterniflora, which was more productive above LMSL, sessile marine biota recruitment to mimic plants was higher in patches below LMSL than above LMSL. Our results highlight an ecological tradeoff at ~LMSL between foundation species restoration and faunal recruitment. Increasing patch size as inundation increases may offset this tradeoff and enhance resilience of restored marshes to sea-level rise.

The missing link in grassland restoration: arbuscular mycorrhizal fungi inoculation increases plant diversity and accelerates succession

Summary Because soil microbial communities are often altered by anthropogenic disturbance, successful plant community restoration may require the restoration of beneficial soil microbes, such as arbuscular mycorrhizal (AM) fungi. Recent evidence suggests that later successional grassland species are more strongly affected by AM fungi relative to early successional plants and that late successional plants consistently benefit from some AM fungi but not other AM fungal species. Many of these late successional species are also often missing in restorations despite being heavily seeded. To assess the effects of AM fungal composition within grassland restorations, we inoculated plots with six different AM fungal community treatments including one of four different AM fungal species isolated from a prairie, a mixture of all four fungal species, and a non‐inoculated control. AM fungi were introduced by planting 16 different inoculated nurse plants into replicated plots. We also seeded the restoration with a diverse, 54 species prairie seed mixture. We found that AM fungal inoculation drove plant community composition; plots inoculated with certain AM fungal treatments were dominated by desirable prairie plants, whereas plots inoculated with other AM fungal species and the non‐inoculated control were dominated by non‐desirable plants including weeds and exotic species. Specifically, we found that many early successional species established well regardless of AM fungal inoculation, whereas the establishment and growth of many late successional species was strongly dependent on the presence of specific AM fungal species. Many conservative late successional species did not occur without inoculation. Overall, total plant community richness, diversity, and Floristic Quality Index were all significantly improved with AM fungal inoculation, whereas we observed that non‐desirable plant abundance was significantly greater in the non‐inoculated plots. Synthesis and applications. Our results suggest that the lack of late successional establishment reported in many previous restorations may be due to ineffective arbuscular mycorrhizal fungal communities at these sites. We conclude that the reintroduction of arbuscular mycorrhizal fungi from reference prairie environments could improve restoration outcomes by promoting plant diversity and richness, especially for desirable later successional plant species, while simultaneously inhibiting less desirable weedy plants.

Assessment of wild and restored staghorn coral Acropora cervicornis across three reef zones in the Cayman Islands

Interest in restoring staghorn coral Acropora cervicornis has grown following the widespread decline of this species in recent decades. To date, thousands of nursery-reared A. cervicornis have been outplanted to restore degraded reefs, but survivorship and growth among outplanted colonies can be spatially variable. In particular, data on distribution of remnant wild populations and outplant performance in varying reef zones is lacking. To address this gap, we conducted a study to characterize existing wild populations and assess performance of nursery-reared, outplanted A. cervicornis among three reef zones of varying depth at Little Cayman Island: the shallow back reef (0–3 m), the intermediate spur-and-groove reef (8–15 m), and the deep reef terrace (>15 m). Wild populations of A. cervicornis were present in each reef zone, and colony height and prevalence of predation by Stegastes spp. were highest in the intermediate zone. For outplanted A. cervicornis, survivorship differed among sites and was lowest for outplants in the deep zone during the 85-day observation period. Post-outplant growth and branching was lowest among outplants in the shallow zone due to high rates of colony breakage. Following the conclusion of the study, a mortality event occurred in which 90% of outplants at the shallow plots died during a period of elevated sea temperature. The information provided in this study suggests that intermediate spur-and-groove reefs are optimal for outplanting activities in Little Cayman using existing restoration methods. These data could be useful for coral restoration practitioners and government agencies in the Caribbean, particularly the Cayman Islands, which is actively expanding its coral nursery program. New strategies must be developed to improve restoration outcomes in shallow and deep zones.

Assisted migration within species range ignores biotic interactions and lacks evidence

AbstractIn the context of climate change, many plant species may have problems adapting or dispersing rapidly enough to keep pace with changing environmental conditions. Given these potential problems, some experts argue against using local plant ecotypes for ecosystem restoration. Instead, they propose to use foreign ecotypes that are adapted to the predicted climate in an approach called assisted migration within species range or predictive provenancing. I argue that such actions may cause a mismatch in biotic interactions and have negative effects on other organisms. As such, assisted migration should only be considered in cases when the local ecotypes would fail to ensure ecosystem services. In fact, there is little experimental evidence on the assisted migration approach so far, and what little there is does not seem to support its use. Even in altered climates, local ecotypes mostly performed equally well or better than foreign ones selected for their adaptations to these climates. The reason is that even if adaptation to climate plays a role, this factor may be overridden by other drivers of local adaptation, such as soil or biotic interactions. Despite assisted migration being a popular concept that is repeatedly commended in scientific literature and propagated among practitioners, it should not be considered a universal tool to improve restoration outcomes during climate change. Given the lack of hard experimental data, I call for large‐scale multispecies experimental studies that will provide the necessary evidence to derive general guidelines and recommendations for management of ecosystems during climate change.

Invasive Plant Management Techniques Alter Arbuscular Mycorrhizal Fungi

Arbuscular mycorrhizal (AM) fungi can improve restoration outcomes by facilitating establishment of native plants. Yet, we know little about the effects of restoration methods on AM fungi. We examined how using herbicide and mowing to remove invasive Brassica nigra (black mustard) might alter AM abundance in a coastal sage scrubland. Black mustard is a non-mycorrhizal plant that produces allelochemicals that inhibit AM fungi. Although black mustard removal could potentially improve AM growth, herbicide and mowing might harm AM fungi. We measured black mustard cover, AM hyphal abundance, and native plant cover from plots exposed to either herbicide or mowing versus untreated controls. We found that both herbicide and mowing reduced black mustard cover. Furthermore, herbicide increased AM abundance in one field site, potentially because herbicide killed black mustard roots and reduced allelochemical production. However, neither restoration treatment improved native plant abundance over the course of our study. Overall, herbicide can deter black mustard invasion and help re-establish the AM community in certain ecosystems, but without a corresponding increase in native plants.

Anchor Chaining’s Influence on Soil Hydrology and Seeding Success in Burned Piñon-Juniper Woodlands

Broadcast seeding is one of the most commonly applied rehabilitation treatments for the restoration of burned piñon and juniper woodlands, but the success rate of this treatment is notoriously low. In piñon-juniper woodlands, postfire soil−water repellency can impair seeding success by reducing soil−water content and increasing soil erosion. Implementing anchor chaining immediately after seeding can improve establishment of seeded species by enhancing seed-to-soil contact and may improve restoration success by decreasing soil−water repellency through soil tillage. The objectives of this research were to 1) determine if anchor chaining in postfire pinyon-juniper woodlands diminishes soil−water repellency, and 2) determine meaningful relationships between soil−water repellency, unsaturated hydraulic conductivity [K(h)], and the establishment of seeded and invasive species. Research was conducted on two study sites, each located on a burned piñon-juniper woodland that had severe water repellency and that was aerially seeded. At each location, plots were randomly located in similar ecological sites of chained and unchained areas. At one location, anchor chaining considerably improved soil hydrologic properties, reducing the severity and thickness of the water-repellent layer, and increasing soil K(h) 2- to 4-fold in the first 2 yr following treatment. At this same location, anchor chaining increased perennial grass cover 16-fold and inhibited annual grass and annual forb cover by 5- and 7-fold, respectively. Results from the second site only showed improvements in soil K(h); other hydrologic and vegetative treatment responses were not significantly improved. Overall, this research suggests that anchor chaining has the potential to improve restoration outcomes, though additional research is warranted for understanding the direct impact of anchor chaining on soil−water repellency without the interaction of a seeding treatment.

Developmental phenology of Persoonia longifolia (Proteaceae) and the impact of fire on these events

Persoonia longifolia R.Br. is a common understorey tree that is difficult to re-establish following bauxite extraction and land restoration in parts of the jarrah forest of south-western Western Australia. To improve restoration outcomes for P. longifolia, understanding its phenology is vital for developing methods for returning this plant to rehabilitated areas. The present study investigated in detail different aspects of the phenology of P. longifolia over a 3-year-period. Most vegetative growth occurred during the summer months and flowering and fruiting occurred concurrently. Fruit matured from July through to September, at which time these dropped to the forest floor. Germination occurred in late winter–early spring from fruit that was at least 1-year old, with poor seedling survival in natural bush (<10%) during the first 12 months. Following fire, P. longifolia plants resprouted prolifically in the next growing season, although there was very little fruit production in the first year following fire. Fruit was not produced until at least the second year following a fire, and when dispersed, required at least another year in the soil seed bank before germination commenced (i.e. 3 years post-fire). Results from the present study will improve restoration outcomes for this species, by providing guidance on better seed-collection strategies and baseline information concerning growth rates under natural conditions that can then be used to assess performance of this species in restored environments.

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.

First-Year Establishment, Biomass and Seed Production of Early vs. Late Seral Natives in Two Medusahead (Taeniatherum caput-medusae) Invaded Soils

AbstractRe-seeding efforts to restore or rehabilitate Great Basin rangelands invaded by exotic annual grasses are expensive and have generally achieved limited success. There is a need to identify new strategies to improve restoration outcomes. We tested the performance of a native early seral seed mix (annual forbs, early seral grasses and shrubs) with that of a native late seral mix representative of species commonly used in restoration when growing with medusahead in soils of contrasting texture (sandy loam and clay loam) through the first growing season after seeding. Natives were also seeded without medusahead. We found that the grasses and forbs in the early seral mix established significantly better than those in the late seral mix, and the early seral mix significantly reduced aboveground biomass and seed production of medusahead by 16 and 17% respectively, likely because of competition with the early seral native forb, bristly fiddleneck. Medusahead performance was reduced in both soil types, suggesting utility of bristly fiddleneck in restoration is not limited to only one soil type. In contrast, the late seral mix did not suppress medusahead establishment, aboveground biomass or seed production. Although the native perennial grasses, particularly early seral species, were able to establish with medusahead, these grasses did not appear to have a suppressive effect on medusahead during the first growing season. Medusahead was able to establish and produce seeds on both soil types, demonstrating an ability to expand its current range in the Intermountain West, though aboveground biomass and seed production was higher in the clay loam. Our results suggest that certain species may play a key role in restoration, and that targeting early seral species in particular to find additional native species with the ability to suppress exotic annual grasses is an important next step in improving restoration outcomes in desert ecosystems.

Harnessing Natural Recovery Processes to Improve Restoration Outcomes: An Experimental Assessment of Sponge-Mediated Coral Reef Restoration

BackgroundRestoration is increasingly implemented to reestablish habitat structure and function following physical anthropogenic disturbance, but scientific knowledge of effectiveness of methods lags behind demand for guidelines. On coral reefs, recovery is largely dependent on coral reestablishment, and substratum stability is critical to the survival of coral fragments and recruits. Concrete is often used to immobilize rubble, but its ecological performance has not been rigorously evaluated, and restoration has generally fallen short of returning degraded habitat to pre-disturbance conditions. Fragments of erect branching sponges mediate reef recovery by facilitating rubble consolidation, yet such natural processes have been largely overlooked in restoring reefs.MethodsOn two reefs in Curacao, four treatments - coral rubble alone, rubble seeded with sponge fragments, rubble bound by concrete, and concrete “rubble” bound by concrete - were monitored over four years to investigate rubble consolidation with and without sponges and the ecological performance of treatments in terms of the number and diversity of coral recruits. Species specific rates of sponge fragment attachment to rubble, donor sponge growth and tissue replacement, and fragment survival inside rubble piles were also investigated to evaluate sponge species performance and determine rates for sustainably harvesting tissue.Findings/SignificanceRubble piles seeded with sponges retained height and shape to a significantly greater degree, lost fewer replicates to water motion, and were significantly more likely to be consolidated over time than rubble alone. Significantly more corals recruited to sponge-seeded rubble than to all other treatments. Coral diversity was also greatest for rubble with sponges and it was the only treatment to which framework building corals recruited. Differences in overall sponge species performance suggest species selection is important to consider. Employing organisms that jump start successional pathways and facilitate recovery can significantly improve restoration outcomes; however, best practices require techniques be tailored to each system.

Grass Seedling Demography and Sagebrush Steppe Restoration

Seeding is a key management tool for arid rangeland. In these systems, however, seeded species often fail to establish. A recent study in Wyoming big sagebrush steppe suggested that over 90% of seeded native grass individuals die before seedlings emerged. This current study examines the timing and rate of seed germination, seedling emergence, and seedling death related to this demographic bottleneck. We seeded monocultures of two native perennial bunchgrasses, Pseudoroegenaria spicata (Pursh) ´ A. L ¨ ove and Elymus elymoides (Raf.) Swezey, and one introduced bunchgrass, Agropyron desertorum (Fisch. ex Link) Schult., in 2007, 2008, and 2009 and tracked sown seed and seedling fate. Across the study years and species we found that germination was rapid and high, with species obtaining 50% germination by December, less than 2 mo after planting. Emergence of germinated seed did not occur until late February for A. desertorum and March for the two native grasses. In 2007 the majority of emergence and death was constrained to several weeks, whereas in 2008 and 2009 emergence and death was distributed across several months. The timing of seedling emergence did not influence survival probability or midday plant water potential (probability of exceedance , 0.05). Survival probabilities once seedlings emerged were greater for native species (0.71) than A. desertorum (0.51) in 2 of the 3 study yr (probability of exceedance . 0.98). The early germination of grasses following fall seeding, and the long 2- to 3-mo period that germinated grass seed remain in the soil before emerging, support the hypothesis that seedling recruitment might be limited largely by ecological processes and conditions during winter or early spring (such as soil freeze–thaw events, seed pathogens, or physical crusts). Delaying seeding to early winter or spring and other management tools that mitigate these factors driving this bottleneck might greatly improve restoration outcomes in these systems.

Demographic processes limiting seedling recruitment in arid grassland restoration

1. Seeding is an important management tool in aridland restoration, but seeded species often fail to establish. Previous research has largely focused on the technical aspects of seeding with little effort directed at identifying demographic processes driving recruitment failures. 2. In tilled plots, in each of 3 years, we estimated life stage transition probabilities for three species commonly used in sage steppe restoration. We also took similar measurements on seed sown by managers following four major fires. 3. Point estimates and associated Bayesian confidence intervals demonstrated germination probabilities that were consistently high, averaging 0·72. However, estimates suggest only 17 and 7% of the germinated seeds emerged in the tilled plots and fire sites, respectively. Following emergence, survival across the seedling, juvenile and adult transitions averaged 0·72. This suggests the transition from a germinated seed to an emerged seedling was the major bottleneck in recruitment. Although most individuals died during emergence, this was not always the principal source of variation in recruitment across sites. 4. Synthesis and applications. Processes occurring after emergence, such as mortality during spring and summer drought, may contribute to site-to-site variation in recruitment but are unlikely to be the main causes of restoration failures. Instead, recruitment may largely be determined by processes occurring during emergence, such as freezing and thawing of the seedbed, development of physical soil crusts and pathogen attack on germinated seeds. Using tools such as seed coatings and soil amendments to manage processes inhibiting emergence and developing seed mixes with higher emergence probabilities are likely to greatly improve restoration outcomes in the sage steppe and similar aridland systems.