Restoration Of Native Species Research Articles

Exploring the potential of topsoil pellets to improve native seedling establishment on degraded agricultural land

Background and aimsAgricultural activities can degrade soils and promote weeds, posing challenges to native species restoration. In agricultural restoration, removing contaminated topsoil is a method designed to reduce elevated soil nutrients caused by fertilisation. This strategy targets weed control by eliminating both aboveground weeds and their soil seed bank before direct seeding. However, it also diminishes native soil seed banks and beneficial soil microbes. We investigated the potential of fresh topsoil pellets containing seeds to improve seedling performance in a degraded grassy woodland where topsoil had been removed.MethodsWe tested various pellet recipes, including one using commercial ingredients and three with different topsoil proportions (30%, 50%, and 70%). The study was conducted in a degraded grassy woodland in southeastern Australia, where topsoil was removed for restoration. We explored the effect of these pellet varieties on seedling emergence and growth of six native species common in this community, as well as microbial activity in the soil surrounding the seedlings.ResultsPellets significantly improved the emergence of Chrysocephalum apiculatum, providing evidence of their effectiveness. However, pellets significantly reduced Arthropodium milleflorum and Glycine tabacina emergence. Linum marginale and Rytidosperma caespitosum emergence remained unaffected by pellets. One species, Bothriochloa macra, had insufficient emergence for analysis. The microbial activity of the soil surrounding Rytidosperma caespitosum seedlings was significantly improved by pellets, with no significant effects observed for other species.ConclusionOur results demonstrate that topsoil pellets improved the emergence of one native species, but reduced emergence for two others, indicating species-specific responses to pelleting.

Seed sowing shifts native–exotic richness relationships in favor of natives during restoration

AbstractA central goal of ecological restoration is to promote diverse ecosystems dominated by native species, but restorations are often plagued by exotic species. A better understanding of factors underlying positive correlations between native and exotic species richness, a pattern that is nearly ubiquitous at large scales in plant communities, may help managers modify these correlations to favor native plant species during restoration. Across 29 tallgrass prairie sites restored through seed sowing onto former agricultural lands, we examined whether the relationship between native and exotic richness is (1) altered by management, such as seed additions and prescribed fire; (2) controlled instead by environmental conditions and successional processes; or (3) altered by management in certain environments and not in others. As is commonly found, native and exotic richness were positively correlated at large scales (i.e., across sites) in this study. Management actions explained much of the remaining variation in native richness, while environmental conditions explained very little. Sites sown with more species at higher seeding rates, especially forb species, had higher native richness than predicted by the native–exotic richness relationship. In contrast, native richness was lower in older restorations than predicted by the native–exotic richness relationship, because native richness, and not exotic richness, declined with restoration age. We show that management actions such as seed sowing can modify the native–exotic richness relationship to favor native species during restoration. The development of management actions that mitigate native species richness declines over time will further benefit native species restoration.

Whole-lake acoustic telemetry to evaluate survival of stocked juvenile fish

Estimates of juvenile survival are critical for informing population dynamics and the ecology of fish, yet these demographic parameters are difficult to measure. Here, we demonstrate that advances in animal tracking technology provide opportunities to evaluate survival of juvenile tagged fish. We implemented a whole-lake telemetry array in conjunction with small acoustic tags (including tags < 1.0 g) to track the fate of stocked juvenile cisco (Coregonus artedi) as part of a native species restoration effort in the Finger Lakes region of New York, USA. We used time-to-event modeling to characterize the survival function of stocked fish, where we infer mortality as the cessation of tag detections. Survival estimates revealed distinct stages of juvenile cisco mortality including high immediate post-release mortality, followed by a period of elevated mortality during an acclimation period. By characterizing mortality over time, the whole-lake biotelemetry effort provided information useful for adapting stocking practices that may improve survival of stocked fish, and ultimately the success of the species reintroduction effort. The combination of acoustic technology and time-to-event modeling to inform fish survival may have wide applicability across waterbodies where receiver arrays can be deployed at scale and where basic assumptions about population closure can be satisfied.

Natural plant revegetation on three reclaimed gold mined sites in South Western Ghana

Mining companies in Ghana have been encouraged by law and policy to reclaim degraded mined sites using native tree species. The study assessed stand structure, compositional dynamics, conservation and economic value of restored species after 20 years of reclamation. Eighty seedlings each of Amphimas ptericarpoides and Macaranga barteri were planted on the first reclaimed site (stand I); 160 seedlings each of Macaranga barteri and Amphimas ptericarpoides on the second (stand II) and third (stand III) reclaimed sites respectively. Each reclaimed site (1000 m 2 ) was inventoried and sampled using 400 quadrats (25 m × 25 m). In all, 123 ‘restored‘ species in 55 families (stand I), 103 species in 52 families (stand II) and 96 species in 49 families (stand III) were identified. Species composition of the reclaimed sites were moderately similar to the old - growth forest remnant. Pioneer species, zoophilous and zoochorous species were dominant in all the reclaimed sites. One hundred and twenty- four adult (DBH > 5 cm) tree species (stand I), 105 (stand II) and 128 (stand III) were obtained. The tree stand structure of the Amphimas reclaimed site had the highest basal area of 13.75 m 2 /ha and most of the adult tree species in all the reclaimed sites were in the lower diameter class (5 cm ≥ DBH < 20 cm). The Genetic Heat Index and Economic Index of trees – only were significantly (p < 0.05) higher in the Amphimas - Macaranga site. The mixed tree species of the Amphimas - Macaranga reclaimed site seem to perform better as almost all measured parameters were dominant on this site. The two tree species used have high potential for restoration of native species. Later studies will further establish the suitability of the two native tree species for reclamation in the study area. • Mined sites were reclaimed with Amphimas pteridocarpus and Macaranga bateri species. • Restored species in the mixed- tree site had higher conservation and economic values. • The tree stand -structure of the A. pteridocarpus site had the highest basal area. • The two tree species used have the potential for restoration of native species.

Shifting Limitations to Restoration across Dryland Ecosystems in Hawaiʻi

Hawaiian dryland ecosystems are important for global biodiversity conservation and contain numerous species threatened with extinction. Over the past century, wildfire frequency and size have increased dramatically because of invasion by fire-promoting non-native invasive species, greatly threatening these ecosystems. Native species restoration is a tool that can disrupt the cycle of increased fire and invasion in lowland dry forest communities, but restoration prescriptions have not been studied systematically in other dryland plant communities. We examined the restoration of three Hawaiian dryland plant communities (a high-productivity Diospyros sandwicensis and Metrosideros polymorpha lowland dry forest (HP), a moderate-productivity Myoporum sandwicense and Sophora chrysophylla dry forest/woodland (MP), and a low-productivity Dodonaea viscosa shrubland (LP)), using a community-assembly framework to understand the abiotic and biotic constraints to species establishment and growth in each community. Because active restoration methods are often needed, at both high and low levels of productivity, we also examined restoration treatments and outcomes across the three sites, which spanned a gradient of rainfall and substrate age. At each site, we used the same factorial field experiment with three factors: habitat quality (high or low), weed control (yes or no), and species addition (none, seeding, or outplanting). Outplants (cohort 1) and seeds were added in the winter of 2009–2010, and outplants were added again in March 2011 (cohort 2). Dispersal limitation was apparent at the LP and HP sites, but was not observed in the MP site, which had, overall, greater native diversity and abundance. Outplant survival was greater in high-quality habitats at the HP site, likely due to reduced abiotic stress. Invasive species were found in greater abundance in certain types of microsites at the LP and MP sites, suggesting that shade or topography can be used to plan restoration and weed-control activities. Overall, active restoration methods improved restoration outcomes at the high- and low-productivity sites, and less so at the moderately productive site. Weed removal and outplanting were effective restoration prescriptions at the LP and HP sites, and habitat quality could also be used to increase survival at the HP site. Active restoration could be a lower priority for moderately invaded, moderate-productivity communities, which have the capability to maintain a native ecosystem state.

Restoring Palmer's agave in a Lehmann lovegrass dominated grassland in southeastern Arizona

Dryland restoration is becoming increasingly challenging in arid and semiarid regions, such as in the southwestern United States, due to rapid land degradation, the spread of non‐native species, and climate change. The development of strategies to enhance restoration of native species, particularly culturally and ecologically important native plants like Palmer's agave (Agave palmeri), is particularly critical in southeastern arid lands where scarce rainfall, herbivory, and invasive species dominance pose unique challenges to land management. In a large field experiment in southeastern Arizona, U.S.A., we assessed the utility of several management techniques to promote restoration and revegetation outcomes for Palmer's agave survival and growth, including protection from solar insolation and herbivory, and reduction in the competitiveness of Lehmann lovegrass (Eragrostis lehmanniana). We found that the combination of herbivory protection and shade resulted in the highest survival of planted agaves, while the shade treatment alone resulted in the largest agaves. In fact, our results suggest that dense Lehmann lovegrass cover protects agaves from direct sunlight and predation. If land managers are challenged by widespread Lehmann lovegrass, they can opt to mechanically reduce it. However, if population recovery of Palmer's agave is a priority and fire hazard is minimal, our work suggests that stakeholders concerned with population recovery of Palmer's agave can forgo removing existing vegetation and plant agaves in a matrix of (and/or under the canopy of) existing vegetation.

Animal legacies lost and found in river ecosystems

Animals can impact freshwater ecosystem structure and function in ways that persist well beyond the animal’s active presence. These legacy effects can last for months, even decades, and often increase spatial and temporal heterogeneity within a system. Herein, we review examples of structural, biogeochemical, and trophic legacies from animals in stream and river ecosystems with a focus on large vertebrates. We examine how the decline or disappearance of many native animal populations has led to the loss of their legacy effects. We also demonstrate how anthropogenically altered animal populations, such as livestock and invasive species, provide new legacy effects that may partially replace lost animal legacies. However, these new effects often have important functional differences, including stronger, more widespread and homogenizing effects. Understanding the influence of animal legacy effects is particularly important as native animal populations continue to decline and disappear from many ecosystems, because they illustrate the long-term and often unanticipated consequences of biodiversity loss. We encourage the conservation and restoration of native species to ensure that both animal populations and their legacy effects continue to support the structure and function of river ecosystems.

Using High-Resolution Remote Sensing to Characterize Suspended Particulate Organic Matter as Bivalve Food for Aquaculture Site Selection

Characterizing relative temporal and spatial variations in both the living and detrital components of bivalve food is required to predict bivalve growth across environments with contrasting seston compositions. The present article describes how remote sensing can be applied for such characterization, both over large spatial scales and fine spatial resolutions (i.e., farm scale; 10's of meters), thereby providing key information for bivalve aquaculture operations and site selection, including the restoration of native species. Using natural seawater samples collected from contrasting culture sites in North America and Europe, a simple model was developed to predict the total particulate organic matter (POM) available as food to bivalves from high-resolution remote-sensing images of coastal embayments which estimate chlorophyll (CHL) and turbidity, in which CHL acts as a proxy for living organics and turbidity as a measure of total suspended particulate matter (SPM). The resulting POM derived from satellite images, along with temperature and CHL, are then used as inputs to the bivalve bioenergetic model, ShellSIM, to predict the growth of Mytilus edulis, Crassostrea virginica, and Ostrea edulis along the coast of Maine, one of the most convoluted coasts in the United States, for aquaculture site selection.

Spatiotemporal interactions of native and introduced salmonid top predators in a large lake: implications for species restoration

Animal interactions are an integral part of a community’s function, with influences ranging from the spatiotemporal habitat use of species to population effects to ecosystem management. Numerous non-native species are established or maintained through stocking in freshwater ecosystems with the potential to affect restoration of native species. Using acoustic telemetry, this study quantified the spatiotemporal co-occurrence of the native top-predator lake trout (Salvelinus namaycush) with non-native Chinook salmon (Oncorhynchus tshawytscha) in Lake Ontario over 2.5 years. Core home range overlap was observed during the summer, with depth acting as a mechanism of segregation, but with potential for interactions during vertical exploration. Fine-scale individual pairwise interactions confirmed the home range results. No horizontal overlap was observed during the winter and spring, but confidence was lower due to poor instrument coverage in deeper water, which the two species may frequent in these seasons. These results demonstrate the importance of depth in understanding fish interactions and highlight the usefulness of considering pairwise species interactions for understanding ecosystem community function to resource managers with multiple projects involving both native and non-native species.

综合物理防控技术对盐城大丰港互花米草的控制效果

互花米草是我国沿海滩涂典型外来入侵物种之一，该物种在江苏盐城大丰港形成了大面积入侵种群。在大丰港设置了刈割+遮荫和单纯刈割样方共9个，对比分析了不同防控技术以及不同遮荫持续时间对互花米草地上部分和地下根茎的影响，评估遮荫去除后互花米草生长状况、土壤氮磷含量、底栖动物生物量和密度的变化，以探索适合的控制技术和有效控制时间。结果表明：两种控制技术都极显著降低了互花米草地上部分株高、基径、密度和地上鲜重（P<0.01），对已刈割的互花米草遮荫3个月、6个月、9个月和12个月后依次去除遮荫网，互花米草地上部分均全部消失，直至第二个生长季均未重新长出幼苗；两种控制技术显著降低了互花米草地下根茎存活率（P<0.05），但控制技术之间和遮荫时间长短对根茎存活率的影响无显著差异；去除遮荫网后，底栖动物生物量显著增加（P<0.05），但土壤氮磷含量无显著变化。研究发现在江苏盐城大丰港实施刈割+遮荫3个月后去除遮荫网，是治理互花米草、恢复本土动植物最高效的防控方法。;Spartina alterniflora is one of the typical invasive alien species along the coast of China. This species has formed a large-scale invasive population in Dafeng Port, Yancheng, Jiangsu. This study set up a total of 9 mowing+shading and only mowing plots in Dafeng Port and analyzed the differences of influences on the upper part and underground rhizomes of S. alterniflora among different control technologies and different lengths of shading time. We further monitored the control effect of S. alterniflora and the impact on soil nitrogen and phosphorus content and macrobenthos after removing the shading net. To explore the shortest shading time required to effectively control Spartina alterniflora. The results showed that the two control technologies extremely significantly reduced the plant height, base diameter, density, and fresh weight of the aboveground plant of S. alterniflora (P<0.01). After mowing+shading was implemented for 3, 6, 9, and 12 months, the shading net was removed in turn, the aboveground part of S. alterniflora disappeared completely, and did not re-grow at the vigorous growth period of the second year. Both of the two control techniques significantly reduced the survival rates of the rhizomes of S. alterniflora (P<0.05). And there was no significant difference among the effects of different control technologies and different lengths of shading time on the survival rate of rhizomes. After removing the shading net, the biomass of macrobenthos increased significantly (P<0.05), but the soil nitrogen and phosphorus content did not change significantly. This study found that removing the shading net after 3 months of mowing+shading control technology in Dafeng Port, Yancheng, Jiangsu Province, is the most efficient prevention and control method for treating Spartina alterniflora and the restoration of native species.

Herb-Layer Dynamics in an Old-Growth Forest: Vegetation–Environment Relationships and Response to Invasion-Related Perturbations

Temperate forests of eastern North America are subject to multiple invasions from non-native species that have the potential to drive long-term dynamics in biodiversity. Garlic mustard (Alliaria petiolata (M. Bieb.) Cavara and Grande) is an invasive plant in many deciduous forests, and management efforts often focus on removing this species to initiate native species restoration. Agrilus planipennis Fairmaire (emerald ash borer; Coleoptera: Buprestidae) is a non-native insect pest that has caused substantial loss of ash trees (Fraxinus spp. L.) in North America. Our goal was to understand how the herbaceous layer in an old-growth forest responded to the removal of a significant invasion of A. petiolata and the loss of Fraxinus spp. due to A. planipennis. Herbaceous diversity and environmental parameters were measured in 32 permanent plots (1 m2 each) from 2012 to 2020 in an old-growth forest remnant that had experienced A. petiolata invasion and subsequent removal as well as mortality of Fraxinus spp. due to A. planipennis. Near-total loss of Fraxinus spp. as a canopy tree was not associated with changes in the understory light environment, possibly due to rapid canopy closure by adjacent trees not susceptible to the insect. Alliaria petiolata removal was associated with changes in herbaceous species richness and possibly shifts in individual species importance. Vegetation–environment relationships remained stable throughout the sampling period, suggesting that resource-related factors that structure the herb layer prevailed throughout the changes associated with Fraxinus spp. mortality and A. petiolata management. From a natural area management perspective, our data offer support for the idea that A. petiolata removal influences herb-layer diversity and indicate that in stands with a diverse tree community, the loss of Fraxinus spp. may not directly influence understory biodiversity.

Ecosystem services from old-fields: Effects of site preparation and harvesting on restoration and productivity of traditional food plants

Highly disturbed landscapes, including fallowed or abandoned farmland, are known to experience losses in native plant diversity that negatively impact the ecological functions and services provided by an ecosystem. The restoration of native species to the post-agricultural landscape using principles derived from indigenous knowledge could reverse this damage. This study examines the effects of three site preparation treatments (prescribed burning, tilling, and mowing) and biomass harvesting on the establishment and productivity of four native, edible, culturally-significant forbs (Apios americana Medik., Helianthus annuus L., Helianthus tuberosus L., and Oenothera biennis L.) restored to a fallow farm field. Species' responses to site preparation treatments varied over three years of observations, with plants grown from tubers establishing populations more successfully after burning or mowing and plants grown from seed establishing better after tillage. Harvesting of biomass after the first growing season reduced the number of individual plants observed for all restored species across all site preparation treatments but demonstrated the potential for production of traditional food resources in a low-management, multi-purpose agroecosystem. H. tuberosus showed particular promise for this purpose, producing an average of 881, 1397, and 1848 kg ha−1 of dry edible biomass on tilled, burned, and mowed plots, respectively. Burning was also found to enhance concentrations of organic matter, calcium, and magnesium in the soil, and many indicators of soil quality varied seasonally. These results indicate that with low-energy input management strategies, native wild edibles could be reintroduced into old-field systems to provide provisioning and cultural ecosystem services while maintaining or enhancing ecosystem function.

Location Matters: Passive and Active Factors Affect the Vertical Distribution of Olympia Oyster (Ostrea lurida) Larvae

Dispersal, retention, and population connectivity are impacted by current regime and the behaviors that drive larval distribution, so understanding both is key to informing restoration of native species like the Olympia oyster (Ostrea lurida) across its range in western North America. This study explores the relationships between several factors (temperature, [chl a], larval size, tidal stage, and estimated current speed) and Olympia oyster larval vertical distributions in Fidalgo Bay (48.4828, − 122.5811), a shallow, tidally flushed bay in the Salish Sea. Olympia oyster larvae collected from four depths over the tidal cycle from July 11–14, 2017, were ~ 20% deeper near slack tide and shallower during the faster parts of both ebb and flood, with a threshold for this transition around an estimated 25 cm s−1. This pattern does not suggest tidally timed migrations as has been shown in another population of Olympia oysters, nor can this pattern be totally explained by passive processes. Larvae did not cluster at depths with specific temperatures or [chl a] but there was a difference in larval size between surface and bottom waters, with older, larger larvae more common at the bottom. Fidalgo Bay does not exhibit two-way flow or strong vertical shear, so vertical distribution of larvae likely has little effect on transport in this system but might in other similarly shallow habitat areas with higher stratification that are target restoration sites in the Salish Sea. These results add to the growing number of studies that show location-specific differences in larval vertical distribution and behavior within taxa and underscore the importance of integrating local hydrodynamics into predictions of bivalve larval transport.

Using Herbicides to Restore Native Species and Improve Habitat on Rangelands and Wildlands

Invasive winter annual grasses are one of the largest threats to the arid and semiarid rangelands and wildlands in the Intermountain West of North America. The most impactful species include downy brome (Bromus tectorum), medusahead (Taeniatherum caput-medusae), ventenata (Ventenata dubia), and to a lesser extent Japanese brome (Bromus japonicus), feral rye (Secale cereale), and jointed goatgrass (Aegilops cylindrica). These winter annuals can germinate in the fall, winter or early spring, exploiting soil moisture and nutrients before native plant communities begin active growth in the spring. These characteristics impart a competitive advantage in the perennial grass dominated natural landscapes of the Intermountain West. Downy brome, a winter annual grass native to Eurasia, is the most widespread invasive species in the western US covering an estimated 22 million ha and a projected 14% annual spread rate. Invasive winter annuals negatively impact these ecosystems by depleting soil moisture and nutrients, reducing native plant productivity and diversity, altering fire frequency, and diminishing pollinator and wildlife habitat. Large amounts of litter which act as a fuel source are left after these grasses senesce early in the summer, greatly increasing the frequency and spread of wildfires in invaded areas. Historically, fire frequency in the 41 million ha sagebrush steppe occurred every 60 to 110 years, but this interval has been shortened to less than every five years since the introduction of invasive annual grasses. Annual grasses quickly (re)invade after these fires while sagebrush (Artemisia spp.), the dominant vegetation type in the sagebrush steppe, can take decades to recover. Therefore, the altered fire regime has resulted in a substantial loss of sagebrush and converted millions of hectares into monocultures of winter annual grass. This altered fire regime also negatively impacted the abundance of small mammals, birds, larger browsing mammals, and pollinating insects in the sagebrush steppe. Managing the weed seedbank is the key to long-term control of invasive winter annual grasses on rangelands and wildlands. Past herbicides have provided adequate short-term control but have often failed due to annual grasses reinvading from the soil seedbank. Indaziflam is a new tool for land managers to achieve multi-year control of the annual grass seedbank while promoting restoration of native species. As wildlife and pollinator habitat continue to be degraded and fragmented through development and agricultural production, indaziflam is a viable option for restoring the rangelands and wildlands impacted by winter annual grasses in the Intermountain West that serve as critical habitat areas.

Invasive legume management strategies differentially impact mutualist abundance and benefit to native and invasive hosts

Determining the best management practices for plant invasions is a critical, but often elusive goal. Invasive removals frequently involve complex and poorly understood biotic interactions. For example, invasive species can leave potent legacies that influence the success of native species restoration efforts, and positive plant‐microbial feedbacks may promote continued reinvasion by an exotic species following restoration. Removal methods can vary in their effects on plant–soil feedbacks, with consequences for restoration of native species. We determined the effects of invasion by a leguminous shrub (French broom; Genista monspessulana) on the density and community composition of, and benefit conferred by, its microbial mutualists in its invading range. Densities of soil‐dwelling rhizobia were much higher in areas invaded by G. monspessulana relative to uninvaded areas, and this increased density of rhizobia fed back to increase seedling growth of both the invader and native legumes. We further compared how three techniques for removing G. monspessulana affected the densities of rhizobia relative to areas where G. monspessulana was still present. Removal by hand‐pulling reduced soil rhizobial densities, and reduced growth of one native legume, while having no effect on the growth of the invader. Overall, our results show that the consequences of restoration techniques, both above‐ and belowground, could be critical for the successful removal of an invasive legume and restoration of native species.

Environmental DNA in lake sediment reveals biogeography of native genetic diversity

Understanding the historical distributions of species is vital to the conservation and restoration of native species, yet such information is often qualitative. We show that the paleolimnological history of threatened freshwater fishes can be reconstructed using species‐diagnostic markers amplified from environmental DNA deposited in lake sediments (lake sedDNA). This method was validated through the detection of lake sedDNA from non‐native trout (Yellowstone cutthroat trout, Oncorhynchus clarkii bouvieri), which corroborated historical records of human‐mediated introductions. We also discovered native trout (westslope cutthroat trout, Oncorhynchus clarkii lewisi) lake sedDNA that predated human‐mediated introductions of freshwater fishes in a watershed with high topographical relief. This unexpected result revealed that the westslope population was of native origin and requires immediate conservation protection. Our findings demonstrate that lake sedDNA can be used to determine the colonization history of freshwater fishes and the structure of ecosystems, aiding in the identification of native ranges, novel native diversity, and introductions of non‐native species.

Improving Ecological Restoration to Curb Biotic Invasion—A Practical Guide

AbstractCommon practices for invasive species control and management include physical, chemical, and biological approaches. The first two approaches have clear limitations and may lead to unintended (negative) consequences, unless carefully planned and implemented. For example, physical removal rarely completely eradicates the targeted invasive species and can cause disturbances that facilitate new invasions by nonnative species from nearby habitats. Chemical treatments can harm native, and especially rare, species through unanticipated side effects. Biological methods may be classified as biocontrol and the ecological approach. Similar to physical and chemical methods, biocontrol also has limitations and sometimes leads to unintended consequences. Therefore, a relatively safer and more practical choice may be the ecological approach, which has two major components: (1) restoration of native species and (2) biomass manipulation of the restored community, such as selective grazing or prescribed burning (to achieve and maintain viable population sizes). Restoration requires well-planned and implemented planting designs that consider alpha-, beta-, and gamma-diversity and the abundance of native and invasive component species at local, landscape, and regional levels. Given the extensive destruction or degradation of natural habitats around the world, restoration could be most effective for enhancing ecosystem resilience and resistance to biotic invasions. At the same time, ecosystems in human-dominated landscapes, especially those newly restored, require close monitoring and careful intervention (e.g., through biomass manipulation), especially when successional trajectories are not moving as intended. Biomass management frequently uses prescribed burning, grazing, harvesting, and thinning to maintain overall ecosystem health and sustainability. Thus, the resulting optimal, balanced, and relatively stable ecological conditions could more effectively limit the spread and establishment of invasive species. Here we review the literature (especially within the last decade) on ecological approaches that involve biodiversity, biomass, and productivity, three key community/ecosystem variables that reciprocally influence one another. We focus on the common and most feasible ecological practices that can aid in resisting new invasions and/or suppressing the dominance of existing invasive species. We contend that, because of the strong influences from neighboring areas (i.e., as exotic species pools), local restoration and management efforts in the future need to consider the regional context and projected climate changes.

Fish Distributions and Habitat Associations in Manistee River, Michigan, Tributaries: Implications for Arctic Grayling Restoration

AbstractRestoration and enhancement of North American native freshwater fishes have for several decades been the subject of growing interest among fisheries biologists, natural resource managers, non‐governmental organizations, and the sportfishing public. The Little River Band of Ottawa Indians (LRBOI) and the Michigan Department of Natural Resources (MDNR), along with universities and public interest groups, are re‐examining the potential for re‐introduction of the Arctic Grayling Thymallus arcticus, a species that has been extirpated in Michigan since the 1930s. The Manistee River, Michigan, flows through the LRBOI's reservation and once supported the last known native Arctic Grayling population in the state's Lower Peninsula. The objectives of this study were to (1) identify potential biotic limitations, such as competition and/or predation from other fish species, that may interfere with Arctic Grayling re‐introduction in the Manistee River watershed; and (2) describe how instream habitat features currently relate to populations of potentially interacting species. Field surveys conducted during June–August 2012 in eight Manistee River tributaries identified suitable abiotic habitat for Arctic Grayling in 20 of 22 sampling reaches. However, high densities of Brown Trout Salmo trutta (a nonnative salmonid) may have influenced some of the habitat associations observed for Brook Trout Salvelinus fontinalis and Slimy Sculpin Cottus cognatus, two species that currently and historically co‐occurred in Arctic Grayling habitats. These two species were the most abundant in river reaches with Brown Trout densities less than 0.10 fish/m2. Based on habitat conditions and Brown Trout densities, there appear to be four distinct tributary regions for which management strategies could be developed to enhance the success of Arctic Grayling re‐introduction efforts. Re‐introduction of Arctic Grayling in the Manistee River watershed would support LRBOI and MDNR goals for native species restoration and would provide a unique and historic angling opportunity that has been absent in Michigan for nearly 100 years.

Development of remote sensing indicators for mapping episodic die-off of an invasive annual grass (Bromus tectorum) from the Landsat archive

The exotic annual grass Bromus tectorum (cheatgrass) dominates vast acreages of rangeland in the western USA, leading to increased fire frequency and ecosystem degradation that is often irreversible. Episodic regeneration failure (“die-off”) has been observed in cheatgrass monocultures and can have negative ecosystem consequences, but can also provide an opportunity for restoration of native species and ecological function within the imperiled sagebrush steppe ecosystem. Proximate causes of cheatgrass die-off are uncertain, although several taxa of fungal soil pathogens have been implicated. Die-off occurrence is stochastic and can occur in remote areas. Thus, developing remote sensing indicators that are repeatable over long time periods, across extensive regions, and at relatively fine spatial resolution would be beneficial for accurately pinpointing events.We developed a remote sensing approach for mapping historical die-off from the Landsat archive (1985–2015), and used this to quantify spatial and temporal patterns of die-off occurrence annually at 30-m resolution. A Random Forests classification of image-derived spectral endmembers, trained on 2014 data, predicted die-off with 93% accuracy (κ=0.845) when applied to independent validation data from 2009. Die-off extent varied greatly across years, though some areas experienced die-off multiple times during the observation period. We found a strong correspondence between die-off occurrence and winter drought conditions, with strongest negative associations with current-year winter precipitation and previous years’ lagged winter and annual precipitation. Die-off duration was heavily skewed towards single-year die-off (81.5% of events), even in localized areas of more frequent occurrence (‘die-off hotspots’).Our retrospective classification of the Landsat archive suggests that cheatgrass die-off occurrence is predictable as the intersection of particular site environmental conditions with annual weather conditions, possibly because they are favorable for disease expression. Associations with previous year conditions suggest that die-off may also depend upon feedbacks between cheatgrass dominance and litter production, suitable sites for seedling establishment, and abundance and persistence of pathogen inoculum. Remote sensing indicators such as those developed in this study are needed to develop hypotheses about die-off causal factors, as well as support improved management of cheatgrass, mitigation for negative consequences associated with die-off (e.g. wind erosion), and successful restoration of native plant communities on die-off areas.

Challenges and limitations to native species restoration in the Great Basin, USA

The Great Basin of the western USA is an arid region characterized by high spatial and temporal variability. The region experienced high levels of ecological disturbance during the early period of Euro-American settlement, especially from about 1870–1935. The principal plant communities of the Great Basin are sagebrush steppes, dominated by various Artemisia shrubs and perennial bunchgrasses that represent the largest rangeland ecosystem in North America. In low to mid-elevation sagebrush communities, exotic annual grasses have displaced native plant species and are associated with a dramatic increase in size and frequency of wildfires. Degradation in this region is driven by processes that cause the loss of mature bunchgrasses, which, when intact, limit exotic annual grass invasion. Historically, large economic investments to restore degraded Great Basin rangeland through establishment of native bunchgrasses, principally utilizing heavily mechanized agronomic approaches, have been met with limited success. A multitude of environmental factors contribute to the lack of restoration success in this region, but seedling mortality from freezing and drought has been identified as a primary demographic limitation to successful bunchgrass establishment. Novel approaches to overcoming limitations to bunchgrass establishment will be required for restoration success. Increased national concern and a near listing of the greater sage-grouse, a steppe-obligate species, to Endangered Species status, has spurred greater regional support and collaboration across a diversity of stakeholder groups such as state and federal land and wildlife management agencies, county planners, and ranchers.