Treesearch

Part 1 of the Science Framework identifies livestock grazing as the most widespread land use in the sagebrush biome (Chambers et al. 2017a; hereafter, Part 1). In the Conservation Objectives Team Report (USDOI FWS 2013) improper livestock grazing is considered a present and widespread threat to Greater sage-grouse (Centrocercus urophasianus; hereafter, GRSG) for most GRSG populations. Livestock grazing affects the composition and structure of plant communities across the sagebrush biome and, consequently, the habitats of GRSG, other species at risk, and high value resources (Boyd et al....

Wild horses (Equus caballus) and wild burros (E. asinus), like domestic livestock, can alter sagebrush ecosystem structure and composition and affect habitat quality for sagebrush dependent species (Beever and Aldridge 2011). The presence of Federally protected wild horses and wild burros can also have substantial effects on the capacity for habitat restoration efforts to achieve conservation and restoration goals. In the Conservation Objectives Team Report (USDOI FWS 2013), the presence of wild horses and burros was considered a threat to Greater sage-grouse (Centrocercus urophasianus;...

Managing for sagebrush ecosystems that are resilient to disturbance and resistant to invasive plants often requires managers to make tough decisions in the face of considerable complexity and uncertainty. The decisionmaking environment is often characterized by multiple management objectives, limited management authority and capabilities, dynamic ecosystems and plant communities, and uncertain responses to management actions. Resource decisionmakers must be able to determine appropriate objectives based on desired management outcomes and sort through the different management considerations...

Wetlands represent the dominant natural source of methane (CH4) to the atmosphere. Thus, substantial effort has been spent examining the CH4 budgets of global wetlands via continuous ecosystem-scale measurements using the eddy covariance (EC) technique. Robust error characterization for such measurements, however, remains a major challenge. Here, we quantify systematic, random and gap-filling errors and the resulting uncertainty in CH4 fluxes using a 3.5 year time series of simultaneous open- and closed path CH4 flux measurements over a sub-boreal wetland. After correcting for high- and...

Microorganisms and termites are the primary wood decay agents in forests of the southeastern United States, whose activity can be affected by forest management practices. Bedding establishes raised planting beds on poorly-drained soils, but little is known about the effect of bedding or soil bed height on wood decomposition. Therefore, a four height bedding study was conducted on a wetland soil in eastern South Carolina: flat (no bedding), half (7.5 cm), single (20 cm), and double (30 cm) above the original soil surface. Aspen (Populus tremuloides Michx.) and loblolly pine (Pinus taeda L.)...

Monitoring programs designed to track ecosystem changes in response to both stressors and disturbances use repeated observations of ecosystem attributes. Such programs can increase our understanding of how interactions among resilience to disturbance, resistance to invasive species, and “change agents” including management actions influence resource conditions (or status) and trends and outcomes of conservation and restoration actions. This type of monitoring information provides the basis for adaptive management. The overarching goal of an integrated monitoring and adaptive management...

Management actions that enable adaptation to climate change and promote resilience to disturbance are becoming increasingly important in the sagebrush biome. In recent decades temperatures have increased, growing seasons have lengthened, and in many areas the timing and amount of precipitation has changed (Chambers et al. 2017 [hereafter, Part 1], section 4; Kunkel et al. 2013a,b,c). Global climate change models are used to project future changes in temperature and precipitation based on relative concentration pathways of likely emissions of carbon dioxide (CO2) and other trace gases and...

Improved use of forest biomass has been presented as a viable option to satisfy a portion of the demand for sustainable alternative sources of energy. Yet, there are considerable gaps in our understanding related to the efficiencies of current state-of-the-art forest biomass recovery systems. Southern pine plantation biomass stands typically exhibit higher stand densities and smaller-diameter trees than conventional stands, which, in turn, may result in reduced recovery efficiencies. In this study, the impact of new harvest systems for biomass recovery was investigated in typical southern...

The Science Framework is part of an unprecedented conservation effort underway across 11 States in the western United States to address threats to sagebrush (Artemisia spp.) ecosystems and the species that depend on them. Sagebrush ecosystems provide a large diversity of habitats and support more than 350 species of vertebrates (Suring et al. 2005). These ecosystems currently make up only about 59 percent of their historical area, and the primary patterns, processes, and components of many sagebrush ecosystems have been significantly altered since Euro-American settlement in the mid-1800s...

Multiple lines of evidence suggest that plant water-use efficiency (WUE)—the ratio of carbon assimilation to water loss—has increased in recent decades. Although rising atmospheric CO2 has been proposed as the principal cause, the underlying physiological mechanisms are still being debated, and implications for the global water cycle remain uncertain. Here, we addressed this gap using 30-y tree ring records of carbon and oxygen isotope measurements and basal area increment from 12 species in 8 North American mature temperate forests. Our goal was to separate the contributions of enhanced...