Guide Restoration Efforts Research Articles

A Fish-Based Tool for the Quality Assessment of Portuguese Large Rivers

Multimetric indices play a pivotal role in assessing river ecological quality, aligning with the European Water Framework Directive (EU WFD) requirements. However, indices developed specifically for large rivers are uncommon. Our objective was to develop a fish-based tool specifically tailored to assess the ecological quality in Portuguese large rivers. Data were collected from seven sites in each of three Portuguese large rivers (Minho, Guadiana, and Tagus). Each site was classified using an environmental disturbance score, combining different pressure types, such as water chemistry, land use, and hydromorphological alterations. The Fish-based Multimetric Index for Portuguese Large Rivers (F-MMIP-LR) comprises four metrics: % native lithophilic individuals; % alien individuals; % migrant individuals; and % freshwater native individuals, representing compositional, reproductive, and migratory guilds. The index showed good performance in separating least- and most-disturbed sites. Least-disturbed sites were rated ‘high’ or ‘good’ by F-MMIP-LR, contrasting with no such classification for most-disturbed sites, highlighting index robustness. The three rivers presented a wide range of F-MMIP-LR values across the gradient of ‘bad’ to ‘high’, indicating that, on a large spatial extent, the biological condition was substantially altered. The F-MMIP-LR provides vital information for managers and decision-makers, guiding restoration efforts and strengthening conservation initiatives in line with the WFD.

A habitat connectivity reality check for fish physical habitat model results and decision‐making for river restoration

Abstract Fish physical habitat models are a tool for guiding restoration efforts in lotic ecosystems, but often they overestimate restoration outcomes because currently they do not incorporate habitat connectivity. This persistent issue can, in extreme cases, result in little or no improvement to fish populations after the restoration, wasting valuable conservation resources. We present a case study where practitioners applied a fish habitat model for multiple life stages of gravel spawning fishes to a 52‐km stretch of the Iller River but did so at a microscale implementation by setting up a model based on cross sections with a maximum of 200 m distance from each other. This approach provided an opportunity to assess the connectivity of habitats for gravel spawning fishes, that is, European Grayling (Thymallus thymallus) and Common Nase (Chondrostoma nasus), integrating probabilities to find suitable habitats for all life‐history stages and seasonal movements. We used the assessed habitat estimates (availability of distinct habitat types within reaches defined by the 200 m cross sections) to calculate the minimum distance a fish would need to overcome to change from one habitat type into the other as it hypothetically ‘grew up’ from egg to full spawning adult. This approach can be interpreted as a life cycle habitat check as it considers all habitat types that are necessary to fulfil the life cycle of gravel spawning fishes including their size, distance and flow direction‐related orientation (e.g. larvae habitats only used when downstream of spawning areas). Our results show that the assumption of complete connectivity would require long movement distances for vulnerable life stages to find suitable habitat. This puts the high priority on the creation of migration corridors and passability of migration barriers in question. Without consideration of habitat types for all life stages of a species and their spatial context, restoration will not be successful. Shortly said: A perfect migration corridor does not necessarily provide habitat connectivity. We recommend the application of the habitat connectivity approach when predicting the effect of restoration measures and particularly setting the priority of measures for mitigation of fish migration.

A bioenergetics‐based index of habitat suitability: Spatial dynamics of foraging constraints and food limitation for a rare estuarine fish

AbstractObjectivesHabitat suitability models can guide restoration efforts in freshwater and estuarine ecosystems by synthesizing important habitat attributes in a single index. Several important elements of the foraging arena of Delta Smelt Hypomesus transpacificus, a small, zooplanktivorous fish, were quantified using a model that combined bioenergetics with physical habitat attributes. We applied the model to evaluate spatiotemporal variation in the suitability of Delta Smelt foraging habitat as indicated by growth potential.MethodsBioenergetics‐based estimates of daily potential growth, given constraints on daily foraging due to temperature, turbidity, day length, and prey availability, were compared to reference growth, estimated separately from length‐at‐age data. We defined suitable foraging arenas for Delta Smelt as times and places when potential growth equaled or exceeded reference growth.ResultAmong six contiguous regions of the upper San Francisco Estuary, temperature was consistently lowest and turbidity highest in the most seaward locations. As a result, predicted growth rates were greater there compared to landward, upstream regions that were warmer and less turbid.ConclusionSimulated habitat augmentation of prey and turbidity revealed that the effects of potential restoration actions could vary regionally as the factors limiting Delta Smelt foraging varied along longitudinal and seasonal gradients. Models of the spatiotemporal variation in Delta Smelt habitat may be substantially improved by directed laboratory studies; however, this research provided a data‐driven example of how dynamic estuarine habitat attributes interact to influence the suitability of foraging arenas experienced by a pelagic fish.

Priority areas and benefits of ecosystem restoration in Beijing.

Ecological restoration can significantly improve ecosystem services and human well-being and provide a basis for regional coordinated development and ecological security. To guide restoration efforts, information on the potential benefits of restoration was required to efficiently target investments. Although the number of studies focusing on ecosystem restoration has increased in recent decades, priority areas that integrate ecological and economic benefits have yet to be identified. We developed and applied a prioritization approach to identify potential priority sites in Beijing. We used the historical environmental data on Beijing to identify areas of degradation and to assess the feasibility of restoration. Ecosystem service and quality degradation, low ecosystem quality, and soil erosion were integrated into one index to indicate the restoration importance. Potential restoration benefits were mapped using the monetary value of six ecosystem services. Based on the importance and benefits of restoration, three scenarios were developed to identify priority restoration areas. In Beijing, restoring 30% of the degraded area (1531 km2) in priority areas by 2050 could increase the annual ecological benefit by more than 5 billion yuan, or approximately 787 million USD, and could decrease the ecological degradation index by 50%. By integrating explicit spatial information on restoration importance and restoration benefits, this methodology provides a feasible way to identify restoration priority areas and assess restoration benefits.

Large‐scale field studies inform adaptive management of California wetland restoration

Salt marsh vegetation provides the structure that supports key wetland functions and the success of wetland restoration efforts depend on the establishment of vegetation, which can take decades. Field experiments aimed at identifying the factors that limit the colonization rate of marsh vegetation can be useful for guiding restoration efforts. We used field experiments and additional measurements to determine the causes for persistently low vegetation cover in a restored salt marsh in southern California. First, we characterized the soil properties of the marsh and found that high salinity and low soil moisture increased with elevation and improved with vegetation. Using this information, we conducted two field experiments—one in the high marsh and the other in the mid marsh to determine the effectiveness of different remedial actions (e.g. irrigation, soil decompaction, soil amendments, and planting and seeding different species) on increasing vegetation cover; the mid marsh experiment evaluated planting and seeding only. In the high marsh, plantings increased cover, and irrigation in combination with soil decompaction facilitated natural plant establishment. In the mid marsh, increases in vegetation cover varied by species planted. In both experiments, the marsh dominant (Salicornia pacifica) naturally recruited, increasing cover whereas seeding did not increase cover. In general, the magnitude and pace of vegetation growth was greater in the mid marsh relative to the high marsh that received less tidal inundation. Collectively, our results show how information gained from experiments conducted during wetland restoration can inform the processes underlying the establishment of vegetation.

Establishing Geomorphic Reference Criteria for Design of River Diversions Around Mine Pits in the Pilbara, Western Australia

The poor condition of river diversion channels can prevent mining companies from relinquishing their mine to the government after mining has ceased. Many regions lack a locally derived template for integrating appropriate geomorphic and hydraulic conditions from unmodified river channels into river diversion designs to help guide post-mining closure activities. Establishing baseline geomorphic reference criteria for unmodified catchments can guide restoration efforts to allow recovery and stability of the fluvial system. Design-wise, channels should be built so that flow conditions are able to move sediment, but not high enough to accelerate erosion in the channel. We used natural headwater channels to inform a regional guide for geomorphic criteria for artificial channels constructed in the Pilbara, Western Australia. We provide guideline hydraulic criteria for specific channel types, including velocity, stream power, and bed shear stress values for five key channel types: alluvial single thread (≥ cobble) and single thread (sand), bedrock/confined channel sections, island-barform channels, and heavily vegetated channels.

A guide to assess distance from ecological baselines and change over time in palaeoecological records

Palaeoecology provides critical data for establishing ecological ‘baselines’, which can guide restoration efforts and be used to assess ecosystem change. However, statistical analyses can be challenging because of the large number of methods available for establishing palaeoecological baselines combined with a lack of practical guidance, particularly around quantifying baselines that include natural variability. We contribute one solution by providing guidance and an R package baselines for using palaeoecological data to (i) define baselines and (ii) test for change over time that incorporates variability. These methods provide an alternative to single-taxon analyses and allow ecosystem complexity to be captured. We use published pollen records as case studies to demonstrate how to establish vegetation baselines for seven localities in New Zealand where relatively recent (c. 1280 AD) and near-simultaneous human settlement across the country allows background environmental disturbance in the pre-human era to be distinguished from anthropogenic disturbance. We present methods for calculating distance from initial sample, distance from baseline in ordination space, allowing incorporation of ecosystem variability, and analysis of rates of change over time using principal curves. We found conventional and Bayesian ordination methods yielded similar results and were effective at identifying change following human settlement, despite the potential for a positive mean-variance relationship to confound results. Principal response curves were most sensitive to a known period of vegetation disturbance caused by volcanic eruptions at two sites with tephra deposits. Our proposed methods, case study and R package baselines are designed to provide a suite of tools to encourage and enable palaeoecological data to be used by palaeoecologists to assess trajectories and change over time, and monitor whether historical management actions have facilitated a change in direction towards a desired baseline state.

Otolith 87Sr/86Sr identifies natal origin, movement and life history of Burbot Lota lota in the Kootenai River following 45 years of impoundment

AbstractHydropower has long been an effective form of renewable energy, but the development of the resource has negatively impacted fishes throughout the world. Formulating recovery plans to mitigate these effects requires a firm understanding of species‐specific provenance, life history and life stage habitat requirements. However, the importance of this information is often only recognised after a substantial population decline, when obtaining it becomes demographically challenging. We provide a case study for this scenario and present a post hoc approach to gain insight into these critical data gaps for Burbot Lota lota in the upper Kootenai River in Montana and British Columbia. The population once supported a robust tribal and recreational harvest but declined following impoundment and these fisheries have remained closed or curtailed for nearly 20 years. The reasons for the decline are unknown and actions to assist recovery have been constrained by limited information regarding natal origin, life history and habitat use. We addressed this issue using strontium isotope ratios (87Sr/86Sr) in otoliths collected over four decades in Lake Koocanusa, the reservoir on the Kootenai River above Libby Dam. Due to the geologic heterogeneity of the basin and resulting variation in water 87Sr/86Sr, the assignment probability for Burbot to their region of natal origin approached unity. Otolith 87Sr/86Sr also indicated the population was comprised of mainstem‐ and tributary‐origin forms and their relative abundance changed over time. Mainstem Burbot was most abundant during the 1970s and 2000s, whereas tributary forms dominated between these periods. We suggest ecosystem changes following impoundment contributed to this shift in life history forms and the overall decline of the population. Our findings underscore the need for additional investigations of these impacts to guide restoration efforts.

Reactive persistence, spatial management, and conservation of metapopulations: An application to seagrass restoration.

Assessing the conditions for persistence of spatially structured populations, especially those that are exploited by humans or threatened by global change, is of critical importance to inform management and conservation efforts. Observations for entire metapopulations are usually incomplete and rarely, if ever, sufficiently long to deduce population persistence from spatial patterns of abundance. Instead, insights based on metapopulation theory are often used for interpreting the demographic trajectories of real populations and for informing management decisions. The classical theoretical tool used to assess conditions for metapopulation persistence is the "invasibility criterion," which characterizes the asymptotic, or long-term, stability of a small colonizing population. Essentially, when the linear operator governing the metapopulation dynamics of an invasion event has a positive eigenvalue, recovery and resistance to extinction (resilience) are implied. The converse, however, is not necessarily the case-an invasion may grow over multiple generations, even when the eigenvalues indicate that extinction will eventually occur, a situation referred to here as "reactive persistence." For the management, restoration, and conservation of real metapopulations subject to continual disturbance, this transient behavior is often more relevant than the asymptotic behavior over long time scales. We develop the theoretical tools for assessing reactive persistence, demonstrating how the conditions for asymptotic and reactive persistence differ in both the patch-occupancy models suited to many terrestrial populations and those where local patch extinctions can be disregarded in the dynamics, often suited to marine species. After presenting the mathematical basis for generalizing the invasibility criterion to include reactive persistence, we illustrate how these concepts and tools can be applied in practice, using as a case study the population ecology and restoration of the seagrass Zostera muelleri (Irmisch ex Ascherson, 1867) in the Port of Gladstone in the Great Barrier Reef World Heritage Area Australia. It is shown how the analysis of the transient dynamics of the Z. muelleri metapopulation can be used to guide restoration efforts. Moreover, it is demonstrated that these reactive persistence concepts provide a more appropriate basis for site prioritization for restoration interventions than traditional stability analysis.

Exotic Grasses Reduce Infiltration and Moisture Availability in a Temperate Oak Savanna.

Biological invasions represent one of the most urgent conservation challenges. Oregon white oak (Quercus garryana) savannas, a complex of grassland and transitional forest, are especially sensitive to these invasions. These ecosystems have been severely degraded and fragmented over the past century and are being encroached by conifers, and oak seedlings are failing to emerge from the understory at many locations. Understanding competitive interactions between Oregon white oak and associated native and exotic vegetation would provide insight into forest-grassland dynamics and the role of exotic grasses in the decline of native species, the processes that maintain temperate savanna ecosystems, and the role of soil water uptake by individual savanna species in contributing to overall species assemblages. In this study, we quantified the soil moisture budget for invaded and uninvaded oak-associated ecosystems. From February to October 2007 we used a split paired plot experiment in Duncan, British Columbia, Canada to measure soil moisture on treatment sites where exotic grasses were removed with herbicide and control plots where they were not, using three depths (5, 20, and 35 or 50 cm) in the soil profile. Our results show that the plots that contained exotic vegetation had a faster rate of soil drying following precipitation events at the 5 cm depth than plots with the predominantly native species. We attribute this difference to the capacity of exotic vegetation to exploit soil moisture more rapidly than native vegetation at times of the year when native vegetation cannot. These results provide insight into one mechanism by which exotic grasses affect associated native plants and could help guide restoration efforts.

Riverscape heterogeneity in estimated Chinook Salmon emergence phenology and implications for size and growth

AbstractMany salmonid‐bearing rivers exhibit thermal and hydrologic heterogeneity at multiple spatial and temporal scales, but how this translates into spatiotemporal patterns of fry emergence is poorly understood. Understanding this variability is important because emergence timing determines the biophysical conditions fish first experience (e.g., temperature, flow, and food supply), thereby influencing growth opportunities and survival during this critical life stage. We predicted spring Chinook Salmon (Oncorhynchus tshawytscha) emergence phenology across four northeastern Oregon subbasins over 5–9 years using empirical spawning and temperature data. We then related interannual emergence timing estimates to juvenile salmon size and growth rates at consistent sampling locations. There were clear longitudinal patterns of predicted emergence timing in each subbasin: The shape of these patterns was consistent among years, but not among subbasins. In two subbasins, emergence occurred progressively later with distance upstream, whereas in the other two subbasins emergence was earliest at upstream sites. Within each year, median emergence dates among sites within each subbasin ranged between 44 and 58 days. This spatial variation was comparable to interannual variation, with median emergence dates for a given location in each subbasin ranging between 47 and 74 days among years. Contrary to our expectations, juvenile salmon were not larger in years with earlier emergence, owing to slower estimated spring and summer growth rates compared to years with later emergence. Despite large interannual variation in estimated emergence dates, these results suggest that other factors (e.g., stream flow, temperature, and density‐dependence) were more important than growth duration in determining juvenile salmon growth rates and size among years. We demonstrated considerable spatial and interannual variation in emergence phenology within these subbasins. Understanding how this variation translates to spatiotemporal patterns of juvenile salmon habitat use, growth, and survival has important implications for guiding restoration efforts and understanding how climate change may impact these populations.

Interacting water, nutrients, and shrub age control steppe grass‐on‐shrub competition: Implications for restoration

AbstractUnderstanding the factors that control grass–shrub interactions and coexistence is critical to the design of dryland management and restoration strategies. Using Stipa tenacissima tussocks as adult neighbor and Olea europaea var. sylvestris as target woody species, we performed a 5‐year‐long, large‐scale manipulative experiment to investigate the independent and combined effects of water and nutrient availability, and the modulating effects of O. europaea ontogeny on the net outcome of grass–shrub interaction. At two contrasting dryland sites, we conducted experimental plantings of Olea seedlings on two microsites: contiguous to a Stipa tussock (Stipa microsite) and on the intertussock bare‐soil areas (Open microsite), and manipulated resource availability by combining nutrient and water addition. The experiment followed a full factorial design, with all treatment combinations applied at each site. We monitored survival, height, and stem basal diameter of Olea individuals over a study period of 5 years. All across the wide range of conditions considered, negative effects of Stipa on Olea largely prevailed during the first 2 years after the plantation. We found that competition was stronger in the drier steppe, where extra inputs of water favored neutral interactions. Conversely, nutrient addition increased competition strength, particularly when combined with water inputs, pointing to the contrasting role of different resources and the importance of interactions between them in the control of plant–plant interaction outcome. The competition effects of Stipa faded with time and gradually shifted to neutral interaction as Olea individuals aged. Our results are particularly relevant to guide restoration efforts in formerly wooded xeric grasslands and rangelands.

Assessment of a Habitat Equivalency Analysis for Freshwater Mussels in the Upper Mississippi River

The upper Mississippi River (UMR) contains diverse, dense, and reproducing assemblages of native freshwater mussels. In the case of an injury to mussels and their habitats, such as a hazardous material spill, train derailment, or barge grounding, resource managers have few restoration strategies. Resource managers need a means to document, quantify, and mitigate adverse effects on mussels resulting from injury. Habitat equivalency analysis (HEA), developed for use with a wide variety of habitat types, is a restoration scaling technique that compares ecological services lost from injury to ecological services gained through restoration actions. The U.S. Fish and Wildlife Service and Iowa Department of Natural Resources modified the HEA for use with native mussels. The mussel HEA has been applied within the UMR to estimate the quantity of restoration needed to compensate the public for injuries to mussels due to contaminant spills and construction projects. Our objective was to describe the UMR HEA for a general audience and assess if the four biological input variables used in the mussel HEA were reasonable based on literature values. We also evaluated the performance of HEA under a range of input scenarios. Although the input estimates used in HEA were within ranges reported in the peer-reviewed literature or were supported by professional judgment in the absence of peer-reviewed literature, outcomes of the mussel HEA were highly variable and would benefit from additional research to reduce uncertainty in the biological inputs. The application of HEA to mussels provides resource managers with a tool to quantify mussel-related ecological services lost from injury and to guide restoration efforts in the UMR.

Seascape Genomics Reveals Metapopulation Connectivity Network of Paramuricea biscaya in the Northern Gulf of Mexico

The degree of connectivity among populations influences their ability to respond to natural and anthropogenic stressors. In marine systems, determining the scale, rate, and directionality of larval dispersal is therefore, central to understanding how coral metapopulations are interconnected and the degree of resiliency in the event of a localized disturbance. Understanding these source-sink dynamics is essential to guide restoration efforts and for the study of ecology and evolution in the ocean. The patterns and mechanisms of connectivity in the deep-sea (>200 m deep) are largely understudied. In this study, we investigated the spatial diversity patterns and metapopulation connectivity of the octocoral Paramuricea biscaya throughout the northern Gulf of Mexico (GoM). Paramuricea biscaya is one of the most abundant corals on the lower continental slope (between 1,200 and 2,500 m) in the GoM. The 2010 Deepwater Horizon oil spill (DWH) directly impacted populations of this species and thus are considered primary targets for restoration. We used a combination of seascape genomic analyses, high-resolution ocean circulation modeling, and larval dispersal simulations to quantify the degree of population structuring and connectivity among P. biscaya populations. Evidence supports the hypotheses that the genetic diversity of P. biscaya is structured by depth, and that larval dispersal among connected populations is asymmetric due to dominant ocean circulation patterns. Our results suggest that there are intermediate unsampled populations in the central GoM that serve as stepping stones for dispersal. The data suggest that the DeSoto Canyon area, and possibly the West Florida Escarpment, critically act as sources of larvae for areas impacted by the DWH oil spill in the Mississippi Canyon. This work illustrates that the management of deep-sea marine protected areas should incorporate knowledge of connectivity networks and depth-dependent processes throughout the water column.

Using recent baselines as benchmarks for megafauna restoration places an unfair burden on the Global South

The potential for megafauna restoration is unevenly distributed across the world, along with the socio‐political capacity of countries to support these restoration initiatives. We show that choosing a recent baseline to identify species' indigenous range puts a higher burden for megafauna restoration on countries in the Global South, which also have less capacity to support these restoration initiatives. We introduce the Megafauna Index, which considers large mammal's potential species richness and range area at the country level, to explore how the responsibility for megafauna restoration is distributed across the world according to four scenarios using various temporal benchmarks to define species' indigenous range – current, historical (1500 AD), mid‐Holocene and Pleistocene. We test how the distribution of restoration burden across the world correlates with indicators of conservation funding, human development and governance. Using a recent or historical baseline as a benchmark for restoration puts a higher pressure on African and south‐east Asian countries while lifting the responsibility from the Global North, where extinctions happened a long time ago. When using a mid‐Holocene or Pleistocene baseline, new opportunities arise for megafauna restoration in Europe and North America, respectively, where countries have a higher financial and societal capacity to support megafauna restoration. These results contribute to the debate around benchmarks in rewilding initiatives and the ethical implications of using recent baselines to guide restoration efforts. We suggest that countries from the Global North should reflect on their responsibility in supporting global restoration efforts, by both increasing their support for capacity building in the Global South and taking responsibility for restoring lost megafauna at home.

Identifying the potential of anadromous salmonid habitat restoration with life cycle models.

An investigation into the causes of species decline should include examination of habitats important for multiple life stages. Integrating habitat impacts across life stages with life-cycle models (LCMs) can reveal habitat impairments inhibiting recovery and help guide restoration efforts. As part of the final elements of the Habitat Restoration Planning model (HARP; Beechie et al. this volume), we developed LCMs for four populations of three species of anadromous salmonids (Oncorhynchus kisutch, O. tshawytscha, and O. mykiss), and ran diagnostic scenarios to examine effects of barrier removal, fine sediment reduction, wood augmentation, riparian shade, restoration of the main channel and bank conditions, beaver pond restoration, and floodplain reconnection. In the wood scenario, spawner abundance for all populations increased moderately (29–48%). In the shade scenario, spring-run Chinook salmon abundance increased the most (48%) and fall-run Chinook salmon and steelhead were much less responsive. Coho responded strongly to the beaver pond and floodplain scenarios (76% and 54%, respectively). The fine sediment scenario most benefitted fall- and spring-run Chinook salmon (32–63%), whereas steelhead and coho were less responsive (11–21% increase). More observations are needed to understand high fine sediment and its impacts. Our LCMs were region-specific, identifying places where habitat actions had the highest potential effects. For example, the increase in spring-run Chinook salmon in the wood scenario was driven by the Cascade Mountains Ecological Region. And, although the overall response of coho salmon was small in the barrier removal scenario (6% increase at the scale of the entire basin), barrier removals had important sub-regional impacts. The HARP analysis revealed basin-wide and regional population-specific potential benefits by action types, and this habitat-based approach could be used to develop restoration strategies and guide population rebuilding. An important next step will be to ground-truth our findings with robust empirically-based estimates of life stage-specific survivals and abundances.

Restoring tropical forest–grassland mosaics invaded by woody exotics

Although important for biological conservation and provisioning of several ecosystem services, tropical forest–grassland mosaics face several threats, one of which is woody invasion in grasslands of these mosaics—an issue proving to be challenging to solve. We present a framework to guide grassland restoration in these mosaics that takes into account their unique ecology, outlines a general chronological sequence of restoration activities, and helps identify research priorities to guide restoration efforts. Specifically, we outline approaches to (1) increase the cost‐effectiveness of restoration programs (e.g. selecting restoration targets and priority sites); (2) restore edaphic processes impacted by woody invasion; (3) maximize the establishment of native grass and forb species, and (4) maintain restored communities in the long‐term by minimizing re‐invasions. We apply this framework to montane southern Indian forest‐grassland mosaics (locally called shola‐grassland mosaics) invaded by nitrogen‐fixing woody exotics to identify research priorities that can act as “game‐changers” in the restoration of these ecosystems. These include (1) identifying invaded areas where passive restoration can be effective, (2) understanding the role of endogenous disturbances, particularly fire, in the spread and management of invasive species and the prevention of re‐invasion, and (3) assessing the role of large‐scale seed farming and emerging seed technologies for the use of seeds to effectively re‐introduce native grassland species. Restoration frameworks that take into account unique ecologies are needed to make the most of the UN Decade on Ecosystem Restoration, and we present such a framework for forest‐grassland mosaics—an important ecosystem that is generally neglected.

Development and Evaluation of Habitat Suitability Criteria for Native Fishes in Three Arizona Streams

AbstractHabitat loss is a main contributor to fish fauna declines in the southwestern USA. Several studies have defined stream‐specific habitat conditions that support the growth and survival of native fish in Arizona to inform stream restoration efforts, yet general habitat use of most individual species across the region is not established. Therefore, we evaluated habitat use of four native fishes, Speckled Dace Rhinichthys osculus, Sonora Sucker Catostomus insignis, Desert Sucker Catostomus clarkii, and Longfin Dace Agosia chrysogaster, across three Arizona streams through the development of habitat suitability criteria (HSC). We developed both stream‐specific and generalized HSC for each species. Generalized HSC were calculated as the combination of stream‐specific HSC for each species. We then assessed the utility of generalized HSC through transferability among study streams. Also, past HSC studies have not considered the occurrence of nonnative species, so we tested whether the presence of nonnative fishes influenced native fish habitat use through logistic regression models. Fish and habitat data were collected along the Mogollon Rim in Arizona during the 2017 summer field season at base flow conditions. We established minimum microhabitat use for four native Arizona fish species through developing HSC. Most generalized criteria did not transfer among study streams due to variation in habitat availability and fish community structure. Logistic regression analysis showed that the presence of nonnative fishes was inversely related to the presence of two native fish species, which could have influenced habitat use of both species. The lack of transferability across streams as demonstrated in this study confirms that only HSC developed in the stream of interest or in similar undegraded streams with comparable fish communities should be used for restoration efforts. For projects to restore native fishes in streams where nonnative competitors will not dominate, the least degraded similar streams without coexisting nonnative fishes can guide restoration efforts.

UAV thermal image detects genetic trait differences among populations and genotypes of Fremont cottonwood (Populus fremontii, Salicaceae)

AbstractMany plants are becoming increasingly maladapted to their environments due to changing climate and environmental conditions. It is, therefore, important to quantitatively evaluate what species, populations, and genotypes will survive in projected climate change scenarios and the implications this can have for associated biodiversity. We evaluate unmanned aerial vehicle (UAV)‐based high‐resolution thermal images for differentiating populations and genotypes in Fremont cottonwood (Populus fremontii S. Wats.), a foundation tree species that supports high levels of biodiversity and associated processes in riparian ecosystems. Specifically, we compare UAV thermal image‐derived tree canopy temperatures among 16 different populations and 10 replicated genotypes within two of the populations of Fremont cottonwood trees sourced from a broad environmental gradient and growing together in a common garden in central Arizona, USA. The UAV image‐derived tree canopy temperatures ranged 30°C–42°C resulting in a high overall accuracy of 85% in tree canopy classification. Our results indicate that the UAV thermal image‐derived mean tree canopy temperatures were significantly different among most of the 16 populations (P < 0.001). Within a warm‐adapted Sonoran Desert population and a cooler High Plateau population, the UAV thermal image‐derived tree canopy temperatures were also significantly different among many genotypes (P < 0.001). Furthermore, the UAV thermal image‐derived tree canopy temperatures were significantly correlated with tree canopy cover (R2 = 0.73; P‐value < 0.001) and varied with locations across the garden. Our findings have important implications for characterizing intraspecific genetic diversity in long‐lived forest trees like Fremont cottonwood and inferences for understanding ecosystem processes and guiding restoration efforts. We suggest that UAV thermal images can be used to rapidly scale laboratory‐ and plot‐based genetics research up to the landscape level. Ecological restoration efforts informed by projected climate scenarios can benefit from the UAV‐based genetics findings to identify future climate‐adapted populations and genotypes for potential propagation sources.

Nine-year physiology, nutrition and morphological development of Picea glauca reintroduced by planting in a high-graded yellow birch–conifer stand

ABSTRACTDepletion of white spruce (Picea glauca) in mixedwood forest is a frequent problem, particularly in stands that were high-graded as a result of inadequate silviculture and spruce budworm (Choristoneura fumiferana) epidemics. To provide information that will help guide restoration efforts, we assessed the effect of four seed-tree retention (STR: 0, 10, 40 and 60 trees/ha) levels and two scarification (SC: patch scarification and disk-trenching) types on white spruce reintroduced by planting in a high-graded yellow birch (Betula alleghaniensis)–conifer stand. We present the 9-year results from the seedling physiology, nutrition and morphology. Physiology and nutrition changed with years, but did not vary with STR levels and SC types. Significant increases in the number of internodal branches, height growth, and total height at the two lowest STR levels and after release suggest that the performance of white spruce in terms of morphology and growth is sensitive to small variations in available light. Because seedling morphology and growth were similar between SC types, a moderate disturbance of the forest floor by disk-trenching would be sufficient at a relatively low cost. Our findings highlight that the STR levels influenced the morphology and growth of planted white spruce seedlings more than the SC types.