SEARCH · USGS Science

Results for “Ecological Restoration”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,549 records · Page 86Linked to original sources

USGS2016

Metapopulation viability of an endangered shorebird depends on dispersal and human-created habitats: Piping plovers ( Charadrius melodus ) and prairie rivers

Background Many species are distributed as metapopulations in dynamic landscapes, where habitats change through space and time. Individuals locate habitat through dispersal, and the relationship between a species and landscape characteristics can have profound effects on population persistence. Despite the importance of connectivity in dynamic environments, few empirical studies have examined temporal variability in dispersal or its effect on metapopulation dynamics. In response to this knowledge gap, we studied the dispersal, demography, and viability of a metapopulation of an endangered, disturbance-dependent shorebird. We examined three subpopulations of piping plovers ( Charadrius melodus ) on the lower Platte and Missouri rivers from 2008–2013. High flow events from an upstream dam on the Missouri River in 2010 and 2011 allowed us to assess the effect of total habitat loss and the subsequent creation of new habitat associated with a large disturbance at one ‘natural’ study location. The other two sites within the metapopulation, which were maintained by anthropogenic activities (e.g., mining, development, habitat restoration), were largely unaffected by this disturbance, resulting in a controlled natural experiment. Results High flow events were associated with increased emigration, decreased immigration, and decreased survival in the subpopulation that experienced high flows. Following the high flow event, immigration into that subpopulation increased. Dispersal rates among subpopulations were negatively correlated with distance. The metapopulation had a low probability of extinction over 100 years (0%) under the current disturbance interval and associated dispersal and survival rates. However, persistence depended on relatively stable, human-created habitats, not the dynamic, natural habitat (47.7 % extinction probability for this subpopulation). Conclusions We found that functional connectivity, as measured by the rate of dispersal among subpopulations, increased as a result of the high flow event in our study metapopulation. Plovers also increased reproductive output following this event. Although the study metapopulation had a low overall probability of extinction, metapopulation persistence depended on anthropogenically created habitats that provided a small but stable source of nesting habitat and dispersers through time. However, all subpopulations remained small, even if persistent, making them individually vulnerable to extinction through stochastic events. Given the highly dynamic nature of habitat availability in this system, maintaining several subpopulations within the metapopulation and stable sources of habitat will be critical, and this species will likely remain conservation-reliant.

Nebraska↗

USGS2015

Crocodylus acutus (American Crocodile). Long distance juvenile movement

Crocodylus acutus (American Crocodile) is the most widely distributed New World crocodilian species with its range extending from Peru in the south to the southern tip of peninsular Florida in the north. Crocodylus acutus occupies primarily coastal brackish water habitat, however it also occurs in freshwater to hypersaline habitats (Thorbjarnarson 2010. In Crocodiles. Status Survey and Conservation Action Plan. [Third Edition], American Crocodile Crocodylus acutus, pp. 46–53 S.C. Manolis and C. Stevenson. Crocodile Specialist Group, Darwin). There is limited literature on long distance movements of juvenile crocodilians worldwide and no literature on juvenile crocodiles in Florida. However, adult C. acutus in Florida have been documented to make seasonal movements of 5–15 km from preferred foraging habitat to nesting beaches (Mazzotti 1983. The Ecology of Crocodylus acutus in Florida. PhD Dissertation. The Pennsylvania State University, University Park, Pennsylvania. 161pp), and one adult was documented making a 35 km trip from her nest site to preferred foraging habitat (Cherkiss et. al. 2006. Herpetol. Rev. 38:72–73). Rodda (1984. Herpetologica 40:444–451) reported on juvenile C. acutus movement in Gatun Lake, Panama, and found that juveniles stayed within 1 km of their nest site for the first month. Movements of juvenile Crocodylus porosus (Saltwater Crocodile) in a river system in Northern Australia showed a maximum movement of 38.9 km from a known nest site, with the majority of the crocodiles staying within 15.6 km downstream to 6.8 km upstream (Webb and Messel 1978. Aust. Wildlife Res. 5:263–283). Juvenile movement of Crocodylus niloticus (Nile Crocodile) in Lake Ngezi, Zimbabwe showed crocodiles restricted their movements from 1.0 km up to 4.5 km through the wet and dry seasons (Hutton 1989. Am. Zool. 29:1033–1049). Long distance movements of alligators were recorded for sizes ranging from 28 cm to 361 cm in a coastal refuge in Louisiana, where the distance traveled ranged from 0.3 km to 90.2 km. The data showed that the smaller alligators moved greater distance than larger ones (Lance et al. 2011. Southeast Nat. 10:389–398). An ongoing 30 year mark and recapture study for Crocodylus acutus in Florida allowed us to look at long distance movement (>30 km) of juveniles (30km). Initial and most recent captures as a juvenile were used to analyze distances moved (Fig. 1). These distances were measured linearly between capture locations. Maximum linear distances of 76.3 km and 69.6 km were recorded for animals 4838 and 6662. All crocodiles moved from nesting habitat through potentially optimal nursery habitat prior to reaching their recapture locations. These juvenile long distance movements could be due to larger crocodiles facilitating their dispersal from the nest location (Lance et al. 2011. op. cit.). These data (Table 1.) support that there is exchange of individuals among the nesting colonies and our ongoing efforts to monitor this threatened species allow us to make observations of how juvenile crocodiles are moving throughout the landscape in an ecosystem currently undergoing restoration.

Herpetological Review↗

USGS2020

Architecture of remnant trees influences native woody plant recruitment in abandoned Hawaiian pastures

Abandoned tropical pastures offer opportunities for passive and active restoration of native forest communities. Tree architecture of remnant canopy trees may be one important factor that can facilitate native plant recruitment in abandoned pastures but has largely been overlooked. Here, we evaluated patterns of native woody plant recruitment under remnant trees in abandoned pastures on Hawai’i Island and how these might be related to both tree architectural features and landscape variables. We measured native woody stems (excluding sprouts of the tree itself) in a 5 m radius around the base of each tree and modeled total basal area of native stems as a function of tree architectural characteristics. Recruitment was positively correlated with tree height as well as horizontal woody area below 1 m (tree structure that occurred below 1 m and was < 45° angle from the ground) around the base of trees. Tall trees likely attract more avian seed dispersers due to their higher visibility on the landscape and increased crown volume. Horizontal woody area likely provides establishment microsites that are above the pasture grass layer, similar to how dead or decaying logs act as nurse substrates. Unlike previous studies, we found little evidence that landscape variables such as distance to the intact forest or nearest canopy neighbor influenced understory recruitment. Tree architectural characteristics can be important predictors of native plant recruitment in abandoned tropical pastures and should be considered in addition to local and landscape-level variables.

Hawaii↗

USGS2023

Fecal metabarcoding of the endangered Pacific pocket mouse (Perognathus longimembris pacificus) reveals a diverse and forb rich diet that reflects local habitat availability

Information on diet breadth and preference can assist in understanding links between food resources and population growth and inform habitat restoration for rare herbivores. We assessed the diet of the endangered Pacific pocket mouse using metabarcoding of fecal samples and compared it to plant community composition in long-term study plots in two populations on Marine Corps Base Camp Pendleton, San Diego County, CA. Fecal samples ( n = 221) were collected between spring 2016 and fall 2017 during monthly live-trap surveys. Concurrently, percent cover and plant phenology were measured in plots centered on trap locations. Fecal samples were sequenced with paired-end reads of the internal transcribed spacer 2 region of the nuclear ribosomal gene, and the resulting amplicons were matched to a regionally specific database. Seventy-three plant taxa were detected, which were mostly forbs and perennial herbs (70–90%). Diet composition differed between populations, years, seasons, and plots. Overall, diet and local habitat composition in plots were significantly correlated. However, we detected some differences in above-ground seed availability and proportion in fecal samples that indicate diet preferences for some forbs, perennial herbs, and native bunch grasses over perennial shrubs and non-native grasses. This is the first study of PPM to pair plant phenology surveys with diet metabarcoding to estimate resource selection, and results suggest that managing habitat for diverse native forb communities and reducing non-native grass cover may be beneficial for this critically endangered species.

California↗

USGS2002

Development of oak plantations established for wildlife

Extensive areas that are currently in agricultural production within the Mississippi Alluvial Valley are being restored to bottomland hardwood forests. Oaks (Quercus sp.), sown as seeds (acorns) or planted as seedlings, are the predominant trees established on most afforested sites. To compare stand development and natural invasion on sites afforested by planting seedlings or by sowing acorns, we sampled woody vegetation on ten 14- to 18-year-old oak plantations established to provide wildlife habitat. Stem densities of about 900 oaks/ha were comparable between stands established by sowing 4000 acorns/ha and stands established by planting 900 seedlings/ha. Densities of oaks in stands established from seedlings increased 38% from densities detected when these stands were 4- to 8-year-old. Densities of oaks established from field-sown acorns increased >100% during this same 10-year span. Oaks that were planted as seedlings were larger than those established from acorns, but trees resulting from either afforestation method were larger than trees naturally colonizing these sites. Natural invasion of woody species varied greatly among afforested sites, but was greater and more diverse on sites sown with acorns. Afforested stands were dominated by planted species, whereas naturally invading species were rare among dominant canopy trees. When afforestation objectives are primarily to provide wildlife habitat, we recommend, sowing acorns rather than planting seedlings. Additionally, planting fewer seeds or seedlings, diversifying the species planted, and leaving non-planted gaps will increase diversity of woody species and promote a more complex forest structure that enhances the suitability of afforested sites for wildlife.

Forest Ecology and Management↗

USGS2020

Estimation of vital population rates to assess the relative health of mussel assemblages in the Upper Mississippi River

Native freshwater mussels are a guild of benthic, filter feeding invertebrates that perform important ecological functions in rivers. Because of their long lifespans (30–50 years or longer), mussels are slow to respond to human‐induced alterations. Thus, development of sensitive indicators of mussel population responses to river conditions and management would be beneficial. Compared to marine species, estimation of vital rates (e.g. survival, growth) in freshwater mussels has received little attention. We placed passively integrated transponder tags on 578 mussels of four species ( Amblema plicata , Cyclonaias pustulosa , Obliquaria reflexa , and Pleurobema sintoxia ) in a well‐studied mussel assemblage in a side channel of the upper Mississippi River. Growth and survival of tagged mussels were assessed annually for 4 years across core (high density) and peripheral (low density) areas of the assemblage. Overall survival was highly variable, ranging from c . 15 to 90%, and was related to life history, habitat quality, and hydrologic events. Survival, which varied significantly among species and over time, was consistently higher in the dense and species‐rich core of the mussel assemblage, relative to the periphery because substrates were consistently more stable in the core of the mussel bed relative to the periphery. Substrate movement during low flows was an order of magnitude lower in the core relative to the periphery, and survival was inversely related to stability of river substrates. Patterns in habitat‐specific survival indicate source–sink population dynamics such that mussels in the core habitat provide recruitment to the periphery, but mussels in the periphery are subject to unsustainably low survival; additional studies to track the source of recruitment in the periphery are needed to test this hypothesis. Growth rate did not vary significantly between core and peripheral areas but did vary by species. Growth rate (proportional change per year) declined with age, and was similar at mean age for A. plicata (0.016 per year), P. sintoxia (0.015 per year), and C. pustulosa (0.013 per year), but much lower for O. reflexa (0.008 per year). Effective management decisions for mussels requires a better understanding of how vital rates govern populations and how they vary across a suite of physical and biological factors. Information on how population vital rates vary among species and over time gives managers another tool to understand how mussels may respond to management actions such as habitat restoration projects. Given the importance of substrate stability inferred from this study, management actions that maintain or increase substrate stability are likely to result in high quality mussel assemblages and may restore a valuable component of ecosystem function in this region.

Minnesota, Wisconsin↗

USGS2009

Mineral Resource Assessment of Marine Sand Resources in Cape- and Ridge-Associated Marine Sand Deposits in Three Tracts, New York and New Jersey, United States Atlantic Continental Shelf

Demand is growing in the United States and worldwide for information about the geology of offshore continental shelf regions, the character of the seafloor, and sediments comprising the seafloor and subbottom. Interest in locating sand bodies or high quality deposits that have potential as sources for beach nourishment and ecosystem restoration is especially great in some regions of the country. The Atlantic coast, particularly New York and New Jersey, has been the focus of these studies for the past 40 years with widely varying results. This study is the first attempt at applying probability statistics to modeling Holocene-age cape-and ridge-associated sand deposits and thus focuses on distinct sand body morphology. This modeling technique may have application for other continental shelf regions that have similar geologic character and late Quaternary sea-level transgression history. An estimated volume of 3.9 billion m3 of marine sand resources is predicted in the cape-and ridge-associated marine sand deposits in three representative regions or tracts on the continental shelf offshore of New York and New Jersey. These estimates are taken from probabilistic distributions of sand resources and are produced using deposit models and Monte Carlo Simulation (MCS) techniques. The estimated sand resources presented here are for only three tracts as described below and for Holocene age sand resources contained in cape-and ridge-associated marine sand deposit types within this area. Other areas may qualify as tracts for this deposit type and other deposit types and geologic ages (for example, paleo-stream channels, blanket and outwash deposits, ebb-tide shoals, and lower sea level-stand deltas), which are present on the New Jersey and New York continental shelf area but are not delineated and modeled in this initial evaluation. Admittedly, only a portion of these probable sand resources will ultimately be available and suitable for production, dependent largely on geographic, economic, preemptive use, environmental, geologic and political factors. In addition, offshore sand resources should only be considered if the area is seaward of the active zone of significant nearshore sediment transport, about 10 to 12 m in depth, and in sufficiently shallow water so that sand can be extracted within U.S. dredging equipment limits, currently about 40 m in depth. If the material is to be used for beach nourishment, material must be of an appropriate sediment texture and character (grain size, sorting, shape, and color) to match the native beach and have mineralogical properties important to its use. Extraction of sand can disturb or alter the benthic habitat and seafloor ecology, so these factors and other site-specific effects will need to be evaluated for any intended use. These and other factors are not considered in this report but can be expected to reduce the total net volume of sand resources available for production. The purpose of this report is to describe and present results from a probabilistic mineral modeling technique previously applied to onshore mineral resources. This modeling and assessment procedure is being used for the first time to assess and estimate offshore aggregate resources; this study is part of the U.S. Geological Survey (USGS) Marine Aggregates Resources and Processes Project (http://woodshole.er.usgs.gov/project-pages/aggregates/).

Bulletin↗

USGS2021

Can the impact of canopy trees on soil and understory be altered using litter additions?

Trees can have large effects on soil nutrients in ways that alter succession, particularly in the case of nitrogen-(N)-fixing trees. In Hawaiʻi, forest restoration relies heavily on use of a native N-fixing tree, Acacia koa (koa), but this species increases soil-available N and likely facilitates competitive dominance of exotic pasture grasses. In contrast, Metrosideros polymorpha (‘ōhi‘a), the dominant native tree in Hawaiʻi, is less often planted because it is slow growing; yet it is typically associated with lower soil N and grass biomass, and greater native understory recruitment. We experimentally tested whether it is possible to reverse high soil N under koa by adding ‘ōhi‘a litter, using additions of koa litter or no litter as controls, over 2.5 yr. We then quantified natural litterfall and decomposition rates of ‘ōhi‘a and koa litter to place litter additions in perspective. Finally, we quantified whether litter additions altered grass biomass and if this had effects on native outplants. Adding ‘ōhi‘a litter increased soil carbon, but increased rather than decreased inorganic soil N pools. Contrary to expectations, koa litter decomposed more slowly than ‘ōhi‘a, although it released more N per unit of litter. We saw no reduction in grass biomass due to ‘ōhi‘a litter addition, and no change in native outplanted understory survival or growth. We conclude that the high N soil conditions under koa are difficult to reverse. However, we also found that outplanted native woody species were able to decrease exotic grass biomass over time, regardless of the litter environment, making this a better strategy for lowering exotic species impacts.

Ecological Applications↗

USGS2025

Small waterbodies of large conservation concern: Towards an integrated approach to more accurately measuring surface water dynamics

Millions of small waterbodies are dispersed throughout the middle of the North American continent, and billions of dollars have been invested to conserve, restore, and manage these waterbodies in the 20th and 21st centuries. Small waterbody conservation has been supported by different stakeholders aiming at improving water quality, enhancing floodwater storage, and supporting migratory bird breeding habitat. Conservation agencies are using hydrological and biological monitoring, modeling, and mapping to adaptively manage small waterbodies in the face of stressors such as invasive species and climate change. As remote sensing estimates of small waterbody surface water extent have become easier to access, understanding the capabilities and limitations of using remote sensing, especially in areas lacking surface water monitoring, is important for conservation decision making. Here, we used in situ monitoring and process-based hydrological modeling to explore remote sensing accuracy, especially related to waterbody size, emergent aquatic vegetation cover, and climatic conditions. Overall, we found that the accuracy of satellite and aerial imagery surface water mapping approaches vastly decreased for waterbodies smaller than 2 ha. We also found emergent vegetation could be masking surface water in waterbodies larger than 2 ha and that accuracy of some remote sensing estimates may decrease during wetter climatic periods. These results indicate that sensors commonly used for surface water applications alone may not be able to accurately detect small waterbody surface water, which supports the need for combining monitoring and modeling to understand how small waterbodies may respond to future changes in climate and land use.

Minnesota↗

USGS2017

Mapping tree canopy cover in support of proactive prairie grouse conservation in western North America

Invasive woody plant expansion is a primary threat driving fragmentation and loss of sagebrush ( Artemisia spp.) and prairie habitats across the central and western United States. Expansion of native woody plants, including conifer (primarily Juniperus spp.) and mesquite ( Prosopis spp.), over the past century is primarily attributable to wildfire suppression, historic periods of intensive livestock grazing, and changes in climate. To guide successful conservation programs aimed at reducing top-down stressors, we mapped invasive woody plants at regional scales to evaluate landscape level impacts, target restoration actions, and monitor restoration outcomes. Our overarching goal was to produce seamless regional products across sociopolitical boundaries with resolution fine enough to depict the spatial extent and degree of woody plant invasion relevant to greater sage-grouse (Centrocercus urophasianus) and lesser prairie-chicken (Tympanuchus pallidicinctus) conservation efforts. We mapped tree canopy cover at 1-m spatial resolution across an 11-state region (508 265 km 2 ). Greater than 90% of occupied lesser prairie-chicken habitat was largely treeless for conifers (< 1% canopy cover), whereas > 67% was treeless for mesquite. Conifers in the higher canopy cover classes (16 − 50% and > 50% canopy cover) were scarce (< 2% and 1% canopy cover), as was mesquite (< 5% and 1% canopy cover). Occupied habitat by sage-grouse was more variable but also had a relatively large proportion of treeless areas ( x − "> x− = 71, SE = 5%). Low to moderate levels of conifer cover (1 − 20%) were fewer ( x − "> x− = 23, SE = 5%) as were areas in the highest cover class (> 50%; x − "> x− = 6, SE = 2%). Mapping indicated that a high proportion of invading woody plants are at a low to intermediate level. Canopy cover maps for conifer and mesquite resulting from this study provide the first and most geographically complete, high-resolution assessment of woody plant cover as a top-down threat to western sage-steppe and prairie ecosystems.

Rangeland Ecology and Management↗

USGS2021

Diversity in spawning habitat use among Great Lakes Cisco populations

Cisco ( Coregonus artedi ) once dominated fish communities in the Laurentian Great Lakes. Restoring the abundance and distribution of this species has emerged as a management priority, yet our understanding of Cisco spawning habitat use is insufficient to characterise habitat needs for these populations and assess whether availability of suitable spawning habitat could be a constraint to recovery. We characterised the distribution of incubating Cisco eggs in situ across gradients of depth and substrate types to describe the spawning habitat used by three Great Lakes populations. In Chaumont Bay, Lake Ontario, eggs were concentrated on shallow bedrock shoals and not found on deeper silt or sand substrate. In contrast, eggs in Thunder Bay, Lake Superior, and Elk Rapids, Lake Michigan, were found on deeper fine grain sediments with low utilisation of shallow rocky and cobble habitats. These patterns of egg incubation habitat use suggest a broad spawning habitat niche at the species level but distinct spawning habitat preferences at the population level. While our results indicate some historical diversity in spawning habitat use has been maintained across the species’ range in the Great Lakes, comparisons of contemporary spawning habitat utilisation against historical accounts raise questions as to whether some spawning habitat use behaviours may no longer be prevalent within specific lakes. Thus, characterising the portfolio of spawning strategies remaining within lakes may improve our understanding of habitat needs and identify opportunities to maintain population diversity while supporting Cisco rehabilitation.

Michigan, New York↗

USGS2012

Spatiotemporal patterns and habitat associations of smallmouth bass (Micropterus dolomieu) invading salmon-rearing habitat

1. Smallmouth bass ( Micropterus dolomieu ) have been widely introduced to fresh waters throughout the world to promote recreational fishing opportunities. In the Pacific Northwest (U.S.A.), upstream range expansions of predatory bass, especially into subyearling salmon-rearing grounds, are of increasing conservation concern, yet have received little scientific inquiry. Understanding the habitat characteristics that influence bass distribution and the timing and extent of bass and salmon overlap will facilitate the development of management strategies that mitigate potential ecological impacts of bass. 2. We employed a spatially continuous sampling design to determine the extent of bass and subyearling Chinook salmon ( Oncorhynchus tshawytscha ) sympatry in the North Fork John Day River (NFJDR), a free-flowing river system in the Columbia River Basin that contains an upstream expanding population of non-native bass. Extensive (i.e. 53 km) surveys were conducted over 2 years and during an early and late summer period of each year, because these seasons provide a strong contrast in the river’s water temperature and flow condition. Classification and regression trees were applied to determine the primary habitat correlates of bass abundance at reach and channel-unit scales. 3. Our study revealed that bass seasonally occupy up to 22% of the length of the mainstem NFJDR where subyearling Chinook salmon occur, and the primary period of sympatry between these species was in the early summer and not during peak water temperatures in late summer. Where these species co-occurred, bass occupied 60–76% of channel units used by subyearling Chinook salmon in the early summer and 28–46% of the channel units they occupied in the late summer. Because these rearing salmon were well below the gape limitation of bass, this overlap could result in either direct predation or sublethal effects of bass on subyearling Chinook salmon. The upstream extent of bass increased 10–23 km (2009 and 2010, respectively) as stream temperatures seasonally warmed, but subyearling Chinook salmon were also found farther upstream during this time. 4. Our multiscale analysis suggests that bass were selecting habitat based on antecedent thermal history at a broad scale, and if satisfactory temperature conditions were met, mesoscale habitat features (i.e. channel-unit type and depth) played an additional role in determining bass abundance. The upstream extent of bass in the late summer corresponded to a high-gradient geomorphic discontinuity in the NFJDR, which probably hindered further upstream movements of bass. The habitat determinants and upstream extent of bass were largely consistent across years, despite marked differences in the magnitude and timing of spring peak flows prior to bass spawning. 5. The overriding influence of water temperature on smallmouth bass distribution suggests that managers may be able limit future upstream range expansions of bass into salmon-rearing habitat by concentrating on restoration activities that mitigate climate- or land-use-related stream warming. These management activities could be prioritised to capitalise on survival bottlenecks in the life history of bass and spatially focused on landscape knick points such as high-gradient discontinuities to discourage further upstream movements of bass.

Pacific Northwest↗

USGS2021

The Chesapeake Bay program modeling system: Overview and recommendations for future development

The Chesapeake Bay is the largest, most productive, and most biologically diverse estuary in the continental United States providing crucial habitat and natural resources for culturally and economically important species. Pressures from human population growth and associated development and agricultural intensification have led to excessive nutrient and sediment inputs entering the Bay, negatively affecting the health of the Bay ecosystem and the economic services it provides. The Chesapeake Bay Program (CBP) is a unique program formally created in 1983 as a multi-stakeholder partnership to guide and foster restoration of the Chesapeake Bay and its watershed. Since its inception, the CBP Partnership has been developing, updating, and applying a complex linked modeling system of watershed, airshed, and estuary models as a planning tool to inform strategic management decisions and Bay restoration efforts. This paper provides a description of the 2017 CBP Modeling System and the higher trophic level models developed by the NOAA Chesapeake Bay Office, along with specific recommendations that emerged from a 2018 workshop designed to inform future model development. Recommendations highlight the need for simulation of watershed inputs, conditions, processes, and practices at higher resolution to provide improved information to guide local nutrient and sediment management plans. More explicit and extensive modeling of connectivity between watershed landforms and estuary sub-areas, estuarine hydrodynamics, watershed and estuarine water quality, the estuarine-watershed socioecological system, and living resources will be important to broaden and improve characterization of responses to targeted nutrient and sediment load reductions. Finally, the value and importance of maintaining effective collaborations among jurisdictional managers, scientists, modelers, support staff, and stakeholder communities is emphasized. An open collaborative and transparent process has been a key element of successes to date and is vitally important as the CBP Partnership moves forward with modeling system improvements that help stakeholders evolve new knowledge, improve management strategies, and better communicate outcomes.

Chesapeake Bay estuary and watershed↗

USGS2020

Stress gradients interact with disturbance to reveal alternative states in salt marsh: Multivariate resilience at the landscape scale

Stress gradients influence many ecosystem processes and properties, including ecosystem recovery from and resistance to disturbance. While recent analytical approaches have advanced multivariate metrics of ecosystem resilience that allow quantification of conceptual resilience models and identification of thresholds of state change, these approaches are not often translated to landscape scales. Using natural and restored salt marshes in Louisiana, USA, we quantified plant community recovery and resistance metrics along flooding stress gradients. n ‐dimensional hypervolumes of plant community biomass and structure were simulated using field data collected from disturbance‐recovery experiments. The relationships between multivariate resilience metrics and flooding stress gradients were then mapped at community‐ and landscape‐relevant scales by scaling with airborne‐derived data across the region. Greater pre‐disturbance abiotic stress decreased live belowground, but not aboveground, biomass, and ultimately led to lower post‐disturbance total recovery, recovery rates, and resistance of plant communities. Vegetated plots flooded >52% of the time transitioned to an alternative, unvegetated state after disturbance. Mapping revealed differences in spatial patterns of resilience‐ highlighting low, interior marsh edges as especially vulnerable to the combination of chronic flooding stress and acute disturbance. At the landscape scale, approximately half of the area (48%) is vulnerable to state change after pulse disturbances. Synthesis . Ultimately, we quantify the ball‐and‐cup conceptual model for a salt marsh ecosystem and its alternative state, mudflat. We find that increasing abiotic stress due to climate change diminishes ecosystem resilience, but the interaction with common episodic disturbances is necessary to reveal transitions to alternative states and quantify state change thresholds. Quantifying and mapping resilience and where alternative states may exist in this fashion improves ecologists’ ability to investigate the mechanisms of stress gradient control on emergent ecosystem properties, while providing spatially explicit resources for managing ecosystems according to their projected resilience.

Louisiana↗

USGS2015

Sediment and nutrient trapping as a result of a temporary Mississippi River floodplain restoration: The Morganza Spillway during the 2011 Mississippi River Flood

The 2011 Mississippi River Flood resulted in the opening of the Morganza Spillway for the second time since its construction in 1954 releasing 7.6 km 3 of water through agricultural and forested lands in the Morganza Floodway and into the Atchafalaya River Basin. This volume, released over 54 days, represented 5.5% of the Mississippi River (M.R.) discharge and 14% of the total discharge through the Atchafalaya River Basin (A.R.B.) during the Spillway operation and 1.1% of the M.R. and 3.3% of the A.R.B. 2011 water year discharge. During the release, 1.03 teragrams (Tg) of sediment was deposited on the Morganza Forebay and Floodway and 0.26 Tg was eroded from behind the Spillway structure. The majority of deposition (86 %) occurred in the Forebay (upstream of the structure) and within 4 km downstream of the Spillway structure with minor deposition on the rest of the Floodway. There was a net deposition of 26 × 10 −4 Tg of N and 5.36 × 10 −4 Tg of P, during the diversion, that was equivalent to 0.17% N and 0.33% P of the 2011 annual M.R. load. Median deposited sediment particle size at the start of the Forebay was 13 μm and decreased to 2 μm 15 km downstream of the Spillway structure. Minimal accretion was found greater than 4 km downstream of the structure suggesting the potential for greater sediment and nutrient trapping in the Floodway. However, because of the large areas involved, substantial sediment mass was deposited even at distances greater than 30 km. Sediment and nutrient deposition on the Morganza Floodway was limited because suspended sediment was quickly deposited along the flowpath and not refreshed by incremental water exchanges between the Atchafalaya River (A.R.) and the Floodway. Sediment and nutrient trapping could have been greater and more evenly distributed if additional locations of hydraulic input from and outputs to the A.R. (connectivity) were added.

Louisiana↗

USGS2002

Demographic consequences of inbreeding and outbreeding in Arnica montana: A field experiment

1. The genetic constitution of populations may significantly affect demography. Founder populations or isolated remnants may show inbreeding depression, while established populations can be strongly adapted to the local environment. Gene exchange between populations can lead to better performance if heterozygosity levels are restored (heterosis), or to reduced performance if coadapted gene complexes are disrupted (outbreeding depression). 2. Five populations of the self-incompatible perennial Arnica montana (Asteraceae) were analysed for the demographic consequences of inbreeding and of intra- and interpopulation outcrossing, using both small and large populations as donors for the latter. We analysed seed production and seed weight and monitored growth, survival and flowering of offspring introduced as seeds and as 4-week-old seedlings in a 4-year field experiment. 3. Reduced seed set after selfing was probably due to the self-incompatibility system rather than to inbreeding depression. There was a significant increase for seed set after interpopulation crosses, which resulted from the alleviation of low mate availability in one of the small populations. 4. Significant inbreeding depression was observed for growth rates of plants introduced as seedlings. We found significant heterosis for flowering probability of plants introduced as seeds, but for plants introduced as seedlings, heterosis for seedling size and flowering probability was only marginally significant. Outbreeding depression was not observed. 5. The results of this study are important for reinforcement measures in small, remnant populations. Significant differences among populations for all measured fitness components suggest that reinforcement is best achieved using material from several populations. 6. The observed higher survival of seedlings as compared with seeds suggests that it is better to plant individuals than to sow. Sowing, however, is easier and cheaper, and was more likely to eliminate poorly adapted genotypes before they contribute to the next generation.

Journal of Ecology↗

USGS2009

Male Kirtland's Warblers' patch-level response to landscape structure during periods of varying population size and habitat amounts

Forest planners must evaluate how spatiotemporal changes in habitat amount and configuration across the landscape as a result of timber management will affect species' persistence. However, there are few long-term programs available for evaluation. We investigated the response of male Kirtland's Warbler (Dendroica kirtlandii) to 26 years of changing patch and landscape structure during a large, 26-year forestry-habitat restoration program within the warbler's primary breeding range. We found that the average density of male Kirtland's Warblers was related to a different combination of patch and landscape attributes depending on the species' regional population level and habitat amounts on the landscape (early succession jack pine (Pinus banksiana) forests; 15-42% habitat cover). Specifically, patch age and habitat regeneration type were important at low male population and total habitat amounts, while patch age and distance to an occupied patch were important at relatively high population and habitat amounts. Patch age and size were more important at increasing population levels and an intermediate amount of habitat. The importance of patch age to average male density during all periods reflects the temporal buildup and decline of male numbers as habitat suitability within the patch changed with succession. Habitat selection (i.e., preference for wildfire-regenerated habitat) and availability may explain the importance of habitat type and patch size during lower population and habitat levels. The relationship between male density and distance when there was the most habitat on the landscape and the male population was large and still increasing may be explained by the widening spatial dispersion of the increasing male population at the regional scale. Because creating or preserving habitat is not a random process, management efforts would benefit from more investigations of managed population responses to changes in spatial structure that occur through habitat gain rather than habitat loss to further our empirical understanding of general principles of the fragmentation process and habitat cover threshold effects within dynamic landscapes.

Forest Ecology and Management↗

USGS2024

Challenges creating monarch butterfly management strategies for electric power companies in the United States

Returning monarch butterflies ( Danaus plexippus ) to sustainable levels of abundance will require an array of contributors to protect and restore habitat over broad areas. Due to the diversity and scale of land managed by electric power companies across the monarch range, plus an additional 32 million hectares needed for new solar arrays by 2050 to meet renewable energy goals, the industry may have potential to contribute to monarch conservation. However, it is challenging to clearly understand an individual company’s potential for monarch conservation because of the scale and distribution of their specific land assets (ranging from 4,800 to 240,000 hectares in this study alone), the complexity of monarch science, and the lack of a science-based approach for evaluating large land assets for monarch habitat. With monarchs potentially being protected under the United States Endangered Species Act in the future and thereby limiting land management approaches, there is interest from electric power companies to understand how their lands relate to monarchs. In collaboration with companies, we developed a GIS-based model to identify company landholdings that contain high-quality monarch habitat and applied the model to specific landholdings of eight power companies in the United States. We then facilitated discussions with company teams to balance conservation goals, corporate risk, and social opinion. This paper describes non-confidential results for developing a national GIS-based monarch habitat model and applying it to electric power companies who are considering monarch conservation while simultaneously transitioning to a new clean energy future. The model and applied experience may be useful for other organizations working across large landscapes to manage monarchs.

conterminous United States↗