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At least 1,153 records · Page 64Linked to original sources

Quantifying landscape ruggedness for animal habitat analysis: A case study using bighorn sheep in the Mojave Desert

Terrain ruggedness is often an important variable in wildlife habitat models. Most methods used to quantify ruggedness are indices derived from measures of slope and, as a result, are strongly correlated with slope. Using a Geographic Information System, we developed a vector ruggedness measure (VRM) of terrain based on a geomorphological method for measuring vector dispersion that is less correlated with slope. We examined the relationship of VRM to slope and to 2 commonly used indices of ruggedness in 3 physiographically different mountain ranges within the Mojave Desert of the southwestern United States. We used VRM, slope, distance to water, and springtime bighorn sheep (Ovis canadensis nelsoni) adult female locations to model sheep habitat in the 3 ranges. Using logistic regression, we determined that the importance of ruggedness in habitat selection remained consistent across mountain ranges, whereas the relative importance of slope varied according to the characteristic physiography of each range. Our results indicate that the VRM quantifies local variation in terrain more independently of slope than other methods tested, and that VRM and slope distinguish 2 different components of bighorn sheep habitat.

Journal of Wildlife Management↗

Factors affecting gadwall brood and duckling survival in prairie pothole landscapes

Waterfowl biologists need reliable predictors of brood and duckling survival to accurately estimate recruitment rates. We examined 30-day survival rates of gadwall (Anas strepera) broods (1992-1994) and ducklings (1990-1994) in eastern North Dakota, USA, during years when water conditions ranged from extremely dry to extremely wet. We evaluated effects of several variables on brood survival : (1) percent of seasonal wetland basins containing water, (2) occurrence of rain on the current or 2 previous exposure days, (3) minimum ambient temperature averaged over the current and 2 previous exposure days, (4) hatch date, (5) duckling age, and (6) brood size. Only 9 of 58 radiomarked females lost their entire broods; Kaplan-Meier 30-day survival rate for broods was 0.84. Brood size (adjusted for hatch date) was a better brood - survival predictor than were any of the environmental variables. Risk of total brood loss decreased by 24% for each additional duckling in the brood . We monitored fates of 212 radiomarked ducklings from 94 broods. Daily risk of death for ducklings was twice as high when seasonal ponds were scarce as when ponds were abundant. Duckling survival rate was lower during the first 7 days of life whether it rained or not; survival rate was greater for 8- to 30-day-old ducklings, but was reduced by rain. Thirty-day duckling survival was greatest when minimum daily temperatures exceeded 10°C and no rain occurred. We attributed 86% of 87 deaths of radiomarked ducklings to predation; American mink (Mustela vison) accounted for ≥68% of the 40 deaths for which predator type could be ascertained. Despite apparent resilience of gadwall populations during drought, our study documented a positive effect of seasonal wetland availability on gadwall duckling survival . Management efforts to improve recruitment will be more effective in years when most seasonal basins contain water.

Minnesota↗

Development of a novel framework for modeling field-scale conservation effects of depressional wetlands in agricultural landscapes

The intermixed cropland, grassland, and wetland ecosystems of the upper mid-western United States combine to provide a suite of valuable ecological services. Grassland and wetland losses in the upper midwestern United States have been extensive, but government-funded conservation programs have protected and restored hundreds of thousands of acres of wetland and grassland habitat in the region. The value of restored wetlands in agricultural fields is complex, and the USDA Natural Resource Conservation Service, Conservation Effects Assessment Project (CEAP) has been lacking the methodology to include these conservation practices in their analyses. Our aim is to develop a reproducible methodology for simulating wetlands within the CEAP cropland modeling framework used to evaluate other agricultural conservation practices. Furthermore, we evaluate the effect of using upland conservation practices on the functioning of restored wetlands. By simulating the addition of a depressional wetland that effectively removes 6% of the field from crop production, we obtained a 15% reduction in annual runoff and a 29% and 28% reduction in mean annual nitrogen (N) and phosphorus (P) losses, respectively. The presence of the depressional wetland in the field is estimated to also reduce edge-of-field losses of sediments by 20% and sediment-bound N and P by 19% and 23%, respectively. Additionally, adding a grass filter strip around the wetland greatly decreased sediment inputs to the wetland, increasing the effective life of the wetland, in terms of its ability to perform valued services, by decades to centuries. Our method for modeling depressional wetlands embedded in cropped fields provides a means to quantify the effects of wetland conservation practices on field-level losses for regional assessments, such as the CEAP.

Journal of Soil and Water Conservation↗

Using videography to quantify landscape-level availability of habitat for grazers: An example with emperor geese in western Alaska

We present a videography approach to estimating large-scale availability of grazing lawns, an important food resource used by broods of emperor geese (Chen canagica) on the Yukon-Kuskokwim Delta, Alaska. Sampling was conducted in 1999, 2003, and 2004 at six locations that encompassed ???40% of the North American population of breeding emperor geese. We conducted ground truthing in 2003 and 2004 to estimate how accurately grazing lawn was classified. Overall, classification accuracy for grazing lawn and non-grazing lawn habitat was greater than 91%. Availability of grazing lawns was stable among years, but varied both among and within locations. Some locations have up to three times as much available grazing lawn, which in combination with densities of geese, likely represents dramatic variation in per capita food availability. Our results suggest that videography is a useful way to sample quickly across a large region and accurately identify fine-scale habitats. We present its use for estimating the availability of a preferred food resource for emperor geese, but the method could be applied to many other cases.

Arctic↗

Potential effects of GPS transmitters on greater sage-grouse survival in a post-fire landscape

Rigorous monitoring and evaluation of wildlife population performance because of management or disturbance often relies upon the handling and marking of animals. Such studies must assume that marking animals does not affect their behavior or demography. We examined survival of greater sage-grouse Centrocercus urophasianus post wildfire in southeastern Oregon, USA. We observed extremely high mortality rates early in the study and questioned if our global positioning systems (GPS) transmitters were negatively affecting survival of adult greater sage-grouse. Thus, in situ we captured and randomly assigned additional grouse to either a GPS or VHF transmitter and examine patterns of mortality and estimated survival to evaluate if there were in fact transmitter effects on this important vital rate. Our results indicated that regardless of instrument type large wildfire had negative effects on monthly survival the first year after the fire. However, point estimates indicated that greater sage-grouse fitted with GPS transmitters had approximately 5% lower annual survival than VHF tagged birds, but although there was relatively large overlap in confidence limits, likely caused by small sample sizes. Further research is needed to disentangle potential confounding effects of GPS transmitters on survival impacts of grouse in association with large disturbance.

Oregon↗

Drought of 1998-2002: impacts on Florida's hydrology and landscape

Lower than normal precipitation caused a severe statewide drought in Florida from 1998 to 2002. Based on precipitation and streamflow records dating to the early 1900s, the drought was one of the worst ever to affect the State. In terms of severity, this drought was comparable to the drought of 1949-1957 in duration and had record-setting low flows in several basins. The drought was particularly severe over the 5-year period in the northwest, northeast, and southwest regions of Florida, where rainfall deficits ranged from 9-10 in. below normal (southwest Florida) to 38-40 in. below normal (northwest Florida). Within these regions, the drought caused record-low streamflows in several river basins, increased freshwater withdrawals, and created hazardous conditions ripe for wildfires, sinkhole development, and even the draining of lakes. South Florida was affected primarily in 2001, when the region experienced below-average streamflow conditions; however, cumulative rainfall in south Florida never fell below the 30-year normal. The four regions of Florida, as referred to throughout this report, are defined based upon U.S. Geological Survey (USGS) data collection regions in Florida. Record-low flows were reported at several streamflow-gaging stations throughout the State, including the Withlacoochee River at Trilby, which reached zero flow on June 10-11, 2000, for the first time during the period of record (1928-2004). Streamflow conditions varied across the State from 31 percent of average flow in 2000 in southwest Florida, to 100 percent of average in 1999 in south Florida. Low-flow recurrence intervals during the drought ranged from less than 2 years at three locations to greater than 50 years at many locations. During the 1998-2002 drought, ground-water levels at many wells across the State declined to elevations not seen in many years. At some wells, ground-water levels reached record lows for their period of record. Florida Water Management Districts responded by issuing water-shortage mandates to curb water use during the spring months of 2000. Generally, freshwater withdrawals increased 13 percent between 1995 and 2000 as a result of the dry conditions. Hundreds of new sinkholes developed across the State. Lake Jackson, in northwest Florida near Tallahassee, experienced its eighth and ninth drawdowns of the past 100 years, and became nearly dry. Numerous other lakes in northern and central Florida experienced similar events. Water restrictions were put into effect in urban areas of the northeast, southwest, and south Florida regions. Wildfires periodically raged over parts of Florida throughout the period, when tinder-dry undergrowth caught fire from lightning strikes or manmade causes. Smoke from these fires caused traffic delays as sections of major highways and interstate lanes forced traffic to slow to a crawl or were closed. Wildfire statistics (Florida Division of Forestry) show that 25,137 fires burned 1.5 million acres between 1998 and 2002. Finally, rainfall that occurred in late 2002, in 2003, and from a tropical storm and four hurricanes in 2004 ended this drought.

Circular↗

High-resolution landscape-scale maps of nutrients, phytoplankton, and related water-quality constituents in Suisun Bay and the Sacramento–San Joaquin Delta, California, during 2018—Results from high-resolution underway surveys

We examined the abundance and distribution of nutrients and phytoplankton in the tidal aquatic environments of the Sacramento–San Joaquin Delta (Delta) and Suisun, Grizzly, and Honker Bays in California by completing three spatial surveys that used continuous underway high frequency (1 hertz) measurements and sampling onboard a high-speed boat. Surveys were conducted in May, July, and October 2018. Water was sampled continuously during surveys to simultaneously collect information about the concentration and spatial distribution of all major nutrient forms together with information about the major classes of phytoplankton and associated standard field measurements of water quality, such as dissolved oxygen, dissolved organic matter, pH, salinity, specific conductance, turbidity, and water temperature. The results show a greater than 50-fold variation in nutrient and phytoplankton concentrations across space and time, providing evidence of the dynamic environmental processes that shape the ways nutrients interact with and affect Delta aquatic habitats.

California↗

Science from genes to landscapes

Wherever flowering plants flourish, pollinating bees, birds, butterflies, bats, and other animals are at work, providing vital and often unnoticed services. Many of these species are in serious decline, a situation if unabated, threatens agricultural production, maintenance of natural plant communities, and other important services. Responding to this urgent challenge, the U.S. Geological Survey (USGS) is part of efforts to provide scientific information to support pollinator conservation, including the implementation of a national pollinator health strategy ( http://www.usgs.gov/ecosystems/wildlife/pollinators/ .) This science is but one example of how the Ecosystems Science Mission Area of the USGS conducts science to support sound management and conservation of our Nation’s biological resources. It does this through research, technical assistance, and education conducted by Cooperative Research Units and Science Centers located in nearly every State. The quality of life and economic strength in America hinges on healthy ecosystems that support living things and natural processes. Ecosystem science better enables society to understand how and why ecosystems change, to predict and forecast future changes, and to guide actions that can prevent damage to, and restore and sustain ecosystems. It is through this knowledge that informed decisions are made about natural resources that can enhance our Nation's economic and environmental well-being.

Fact Sheet↗

Monitoring the southwestern Wyoming landscape—A foundation for management and science

Natural resource monitoring involves repeated collections of resource condition data and analyses to detect possible changes and identify underlying causes of changes. For natural resource agencies, monitoring provides the foundation for management and science. Specifically, analyses of monitoring data allow managers to better understand effects of land-use and other changes on important natural resources and to achieve their conservation and management goals. Examples of natural resources monitored on public lands include wildlife habitats, plant productivity, animal movements and population trends, soil chemistry, and water quality and quantity. Broader definitions of monitoring also recognize the need for scientifically valid data to help support planning efforts and informed decisions, to develop adaptive management strategies, and to provide the means for evaluating management outcomes.

Wyoming↗

Fate of carbon in Alaskan Landscapes Project: Database for soils from eddy covariance tower sites, Delta Junction, AK

Soils in Alaska, and in high latitude terrestrial ecosystems in general, contain significant amounts of organic carbon, most of which is believed to have accumulated since the start of the Holocene about 10 ky before present. High latitude soils are estimated to contain 30-40% of terrestrial soil carbon (Melillo et al., 1995; McGuire and Hobbie, 1997), or ~ 300-400 Gt C (Gt = 1015 g), which equals about half of the current atmospheric burden of carbon. Boreal forests in particular are estimated to have more soil carbon than any other terrestrial biome (Post et al., 1982; Chapin and Matthews, 1993). The relations among net primary production, soil carbon storage, recurrent fire disturbance, nutrients, the hydrologic cycle, permafrost and geomorphology are poorly understood in boreal forest. Fire disturbance has been suggested to play a key role in the interactions among the complex biogeochemical processes influencing carbon storage in boreal forest soils (Harden et al., 2000; Zhuang et al., 2002). There has been an observed increase in fire disturbance in North American boreal black spruce (Picea mariana) forests in recent decades (Murphy et al., 1999; Kasichke et al., 2000), concurrent with increases in Alaskan boreal and arctic surface temperatures and warming of permafrost (Osterkamp and Romanofsky, 1999). Understanding the role of fire in long term carbon storage and how recent changes in fire frequency and severity may influence future high latitude soil carbon pools is necessary for those working to understand or mitigate the effects of global climate change.

Alaska↗

The geochemical landscape of northwestern Wisconsin and adjacent parts of northern Michigan and Minnesota (geochemical data files)

This data set consists of nine files of geochemical information on various types of surficial deposits in northwestern Wisconsin and immediately adjacent parts of Michigan and Minnesota. The files are presented in two formats: as dbase files in dbaseIV form and Microsoft Excel form. The data present multi-element chemical analyses of soils, stream sediments, and lake sediments. Latitude and longitude values are provided in each file so that the dbf files can be readily imported to GIS applications. Metadata files are provided in outline form, question and answer form and text form. The metadata includes information on procedures for sample collection, sample preparation, and chemical analyses including sensitivity and precision.

Michigan, Minnesota, Wisconsin↗

Hurricane Mitch: Landscape Analysis of Damaged Forest Resources of the Bay Islands and Caribbean Coast of Honduras

The advent of analog and digital video has provided amateur photographers with professional-like technology to capture dynamic images with ease and clarity. Videography is also rapidly changing traditional business and scientific applications. In the natural sciences, camcorders are being used largely to record timely observations of plant and animal behavior or consequence of some catastrophic event. Spectacular video of dynamic events such as hurricanes, volcanic eruptions and wildfire document the active process and aftermath. Scientists can analyze video images to quantify aspects of a given event, behavior, or response, temporally and spatially. In this study we demonstrate the simple use of an aerial application of videography to record the spatial extent and damage expression of mangrove forest in the Bay Islands and mainland coast of northern Honduras from wind damage following Hurricane Mitch (1998). In this study, we conducted a video overflight of coastal forests of the Bay Islands and mainland coast of northern Honduras 14 months after impact by Hurricane Mitch (1998). Coastal areas were identified where damage was evident and described relative to damage extent to forest cover, windfall orientation, and height of downed trees. The variability and spatial extent of impact on coastal forest resources is related to reconstructed wind profiles based on model simulations of Mitch's path, strength, and circulation during landfall.

Open-File Report↗

Grass buffers for playas in agricultural landscapes: An annotated bibliography

This bibliography and associated literature synthesis (Melcher and Skagen, 2005) was developed for the Playa Lakes Joint Venture (PLJV). The PLJV sought compilation and annotation of the literature on grass buffers for protecting playas from runoff containing sediments, nutrients, pesticides, and other contaminants. In addition, PLJV sought information regarding the extent to which buffers may attenuate the precipitation runoff needed to fill playas, and avian use of buffers. We emphasize grass buffers, but we also provide information on other buffer types. There are a number of relatively synonymous terms that describe grass buffers for wetlands. They include: buffer strip, vegetated filter strip (VFS), grass buffer, grass filter, grass hedge, and grassed waterway (GW), among others (see McKague and others, 1996). Although some of these terms represent slightly different designs, placements, and/or purposes, they all perform similar functions. In this document, we use ‘buffer’ and VFS more or less interchangeably; other types are specified by name (e.g., grass hedges). Our bibliography is by no means exhaustive, as the body of literature potentially relevant to playas and wetland buffers is vast. Thus, we attempted to include and annotate at least 1–3 papers by numerous researchers heavily involved in buffer research and modeling. We also included single papers by other researchers to increase the spectrum of regional focus, watershed/wetland conditions, research approaches, researcher expertise, and the time over which buffer theories/practices have evolved. We found virtually no literature specific to buffers for playas (confirmed by D.A. Haukos, oral. commun., 2005); thus, we conducted interviews with playa scientists to glean information on possible buffer design and management specifically for playas. We did, however, find a significant body of literature on the results of controlled experiments designed to test buffer effectiveness, an important first step towards validating buffer effectiveness in real-world situations. Of the literature on playa ecology, flora, and wildlife, we found that most focuses on playa basins and wetlands rather than the surrounding uplands and grasslands; furthermore, most of the empirical work on playa ecology has taken place in the Southern High Plains (SHP; i.e., Texas and Oklahoma panhandles, southeastern Colorado, and southwestern Kansas) because many wetlands in other portions of the PLJV region (Fig. 1) were only recently recognized as playas. Finally, we found few papers on avian use of buffers; therefore, we focused on those that report on avian use of Conservation Reserve Program (CRP) fields or lands enrolled in similar programs. References on best management practices (BMPs) for agricultural lands were included because certain BMPs are crucial for informing decisions about buffer design/ effectiveness and overall playa ecology. We also included various papers that increase the spectrum of time over which buffer theories and practices have evolved. An unannotated section lists references that we did not prioritize for annotation and references that may be helpful but were beyond the scope of this document. Finally, we provide notes on conversations we had with scientists, land managers, and other buffer experts whom we consulted, and their contact information. We conclude the bibliography with appendices of common and scientific names of birds and plants and acronyms used in both the bibliography. In the annotations, italicized text signifies our own editorial remarks. Readers should also note that much of the work on buffers has been designed using English units of measure rather than metrics; in most cases, their results have been converted to metrics for publication, explaining the seemingly odd or irregular buffer widths and other parameters reported.

Open-File Report↗