Publications by authors named "Devan McGranahan"

Understanding how management influences forage nutritive value and grazer selection within grazing seasons is an ongoing effort for researchers and land managers globally. We used six, 65 ha pastures managed with patch-burn grazing and stocked with either cow-calf pairs (0.45-0.

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Fuel and weather interact to affect wildland fire behavior, but little is known about associations between these variables in the northern Great Plains of North America. Few studies consider rate of spread or statistically test the influence of fuel and weather. We measured overall fuel load and moisture ahead of prescribed fires in North Dakota, USA, and used a thermocouple array to measure two-dimensional rate of spread, soil surface temperature, and aboveground flame temperature, to compare with fire weather data.

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Invasive annual grasses alter fire regime in steppe ecosystems, and subsequent trends toward larger, more frequent wildfires impacts iconic biodiversity. A common solution is to disrupt novel fuel beds comprising continuous swaths of invasive annual grasses with greenstrips-linear, human-maintained stands of less-flammable vegetation. But selecting effective native species is challenged by the fact that identifying the optimal combination of plant traits that interrupt wildfire spread is logistically difficult.

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Land-use and land-cover change associated with agriculture is one of the main drivers of biodiversity loss. In heavily modified agricultural landscapes, grazing lands may be the only areas that can provide essential resources for native grassland species. Management decisions, such as choice of livestock species, affect the extent to which grazing lands provide suitable habitat for native species such as pollinators.

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Within agricultural landscapes, native bees often rely on limited natural and seminatural lands to provide the majority of the food and nesting resources that sustain them. To understand better how management can affect pollinators in these seminatural areas, we compared how sheep or cattle herbivory influenced floral resources and bee communities in low-diversity, former Conservation Reserve Program (CRP) pastures managed with patch-burn grazing. We sampled bee communities and floral resources three times per season in 2017, 2018, and 2019.

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Article Synopsis
  • The study examined how traffic from shale petroleum development affects dust exposure in rural landscapes, specifically in the Bakken region.
  • Dust deposition was significant up to 180 meters from unpaved roads, yet it did not impact the abundance or behavior of birds and invertebrates in agricultural areas.
  • The results indicate that wildlife in intensified agricultural environments can withstand additional disturbances from energy development, unlike species in undisturbed habitats.
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Applications for exploratory shale gas development via hydraulic fracturing (fracking) have raised concern about energy development impacts in South Africa. Initially, focus was on the arid Karoo, but interest now includes KwaZulu-Natal, a populous, agricultural province with high cultural, ecological, and economic diversity. We conducted focus groups and an online survey to determine how some South Africans perceive fracking.

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Land-use change has resulted in rangeland loss and degradation globally. These changes include conversion of native grasslands for row-crop agriculture as well as degradation of remaining rangeland due to fragmentation and changing disturbance regimes. Understanding how these and other factors influence wildlife use of rangelands is important for conservation and management of wildlife populations.

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Ecologists have used Global Positioning Systems (GPS) to track animals for 30 years. Issues today include logging frequency and precision in estimating space use and travel distances, as well as battery life and cost. We developed a low-cost (~US$125), open-source GPS datalogger based on Arduino.

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Heterogeneous disturbance patterns are fundamental to rangeland conservation and management because heterogeneity creates patchy vegetation, broadens niche availability, increases compositional dissimilarity, and enhances temporal stability of aboveground biomass production. Pyrodiversity is a popular concept for how variability in fire as an ecological disturbance can enhance heterogeneity, but mechanistic understanding of factors that drive heterogeneity is lacking. Mesic grasslands are examples of ecosystems in which pyrodiversity is linked strongly to broad ecological processes such as trophic interactions because grazers are attracted to recently burned areas, creating a unique ecological disturbance referred to as the fire-grazing interaction, or pyric herbivory.

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Fire is a process that shaped and maintained most terrestrial ecosystems worldwide. Changes in land use and patterns of human settlement have altered fire regimes and led to fire suppression resulting in numerous undesirable consequences spanning individual species and entire ecosystems. Many obvious and direct consequences of fire suppression have been well studied, but several, albeit less obvious, costs of alteration to fire regimes on wildlife are unknown.

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Ecosystems worldwide have been subject to new or intensified energy development facilitated by technologies such as horizontal drilling and hydraulic fracturing, activity that has generated concern for air, water, biotic, and social resources. Application of these technologies in the development of the Bakken oil patch has made it one of the most productive petroleum plays in North America, causing unprecedented landscape industrialization of otherwise rural, agricultural counties in western North Dakota. The region is isolated, and development impacts have not been well-studied.

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Ecological theory predicts that diversity decreases variability in ecosystem function. We predict that, at the landscape scale, spatial variability created by a mosaic of contrasting patches that differ in time since disturbance will decrease temporal variability in aboveground plant biomass. Using data from a multi-year study of seven grazed tallgrass prairie landscapes, each experimentally managed for one to eight patches, we show that increased spatial variability driven by spatially patchy fire and herbivory reduces temporal variability in aboveground plant biomass.

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Soils contain much of Earth's terrestrial organic carbon but are sensitive to land-use. Rangelands are important to carbon dynamics and are among ecosystems most widely impacted by land-use. While common practices like grazing, fire, and tillage affect soil properties directly related to soil carbon dynamics, their magnitude and direction of change vary among ecosystems and with intensity of disturbance.

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