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Author: Sienna A. Wessel Publisher: ISBN: Category : Restoration ecology Languages : en Pages : 78
Book Description
In order for restoration to meet its full potential, we must disentangle mechanisms that drive community trajectories with attention to those that can be manipulated by practitioners. Community assembly theory proposes that ecological communities are contingent upon dispersal and environmental filtering processes during establishment. We leveraged an ongoing sagebrush steppe restoration project to test the relative influence of restoration age and establishment conditions on composition and traits. We surveyed 13 sites for over a decade post-seeding and collected data on 5 functional traits in restored and reference communities. Sites were seeded with different mixes across multiple years and represented gradients of soil texture and productivity. Using multivariate analyses and mixed effects models to quantify trajectories, we determined the relative influence of drivers and tested the predictability of traits compared to compositional metrics. Communities followed clear successional paths with age but did not meet targets after 11 years. Trajectories were also mediated by establishment conditions. Climatic variation between planting years frequently explained as much or more variation in outcomes as soil properties and seed mix design, especially for trait metrics which were less responsive to time. Overall predictability was not higher for trait metrics, however, the fact that traits were more responsive to climatic factors was consistent with theory. Our findings support the existence of persistent establishment contingencies which affect species and traits in distinct ways through time. Restoration success may be improved by considering climatic variation and timing of planting, factors which are largely ignored under the current paradigm.
Author: Sienna A. Wessel Publisher: ISBN: Category : Restoration ecology Languages : en Pages : 78
Book Description
In order for restoration to meet its full potential, we must disentangle mechanisms that drive community trajectories with attention to those that can be manipulated by practitioners. Community assembly theory proposes that ecological communities are contingent upon dispersal and environmental filtering processes during establishment. We leveraged an ongoing sagebrush steppe restoration project to test the relative influence of restoration age and establishment conditions on composition and traits. We surveyed 13 sites for over a decade post-seeding and collected data on 5 functional traits in restored and reference communities. Sites were seeded with different mixes across multiple years and represented gradients of soil texture and productivity. Using multivariate analyses and mixed effects models to quantify trajectories, we determined the relative influence of drivers and tested the predictability of traits compared to compositional metrics. Communities followed clear successional paths with age but did not meet targets after 11 years. Trajectories were also mediated by establishment conditions. Climatic variation between planting years frequently explained as much or more variation in outcomes as soil properties and seed mix design, especially for trait metrics which were less responsive to time. Overall predictability was not higher for trait metrics, however, the fact that traits were more responsive to climatic factors was consistent with theory. Our findings support the existence of persistent establishment contingencies which affect species and traits in distinct ways through time. Restoration success may be improved by considering climatic variation and timing of planting, factors which are largely ignored under the current paradigm.
Author: Michael D. Reisner Publisher: ISBN: Category : Languages : en Pages : 540
Book Description
Sagebrush steppe ecosystems are one of the most widespread but endangered ecosystems in North America. A diverse array of human-related stressors has gradually compromised these ecosystems' resilience to disturbance and invasion by Bromus tectorum (cheatgrass). The role of the foundational shrub Artemisia as a driver of herbaceous community structure and dynamics during this degradation process is poorly understood. Many of the individual factors driving B. tectorum invasions are well documented. However a predictive understanding of the relative importance of complex, interacting factors in the causal network of simultaneously occurring processes determining invasibility has proven elusive. I examined these issues at the landscape level across 75 sites capturing a range of soil and landscape properties and cattle grazing levels similar to those found across the Great Basin. Cumulative cattle herbivory stress levels were a predominant component of both the overlapping heat and water stress gradients driving the structure of Artemisia interactions with herbaceous species. Consistent with the stress gradient hypothesis, Artemisia facilitation of herbaceous species was most frequent and strongest at the highest stress levels, and competition was most frequent and strongest at the lowest stress levels. The two species with the highest competitive response abilities, Elymus elymoides and Poa secunda, showed the strongest facilitation at the upper limits of their stress tolerances. The structure of Artemisia interactions with the invasive B. tectorum was strikingly different than those with native bunchgrasses. Artemisia interactions with native bunchgrasses shifted from competition to facilitation with increasing heat, water, and herbivory stress, but its interactions remained competitive with B. tectorum along the entire stress gradient. Shifts in the structure of interactions between Artemisia and native bunchgrasses were associated with both an increase and decrease in community compositional and functional stability. I report the first evidence of native species facilitation decreasing community invasibility. Artemisia facilitation increased native bunchgrass composition, which reduced the magnitude of B. tectorum invasion in under-shrub compared to interspace communities. This decreased invasibility did not translate into lower invasibility at the community level because of the limited spatial scale over which such facilitation occurs. Artemisia facilitation increased community compositional and functional stability at intermediate stress levels but decreased community stability at high stress levels. Facilitation became a destabilizing force when native bunchgrass species became "obligate" beneficiaries, i.e. strongly dependent on Artemisia facilitation for their continued persistence in the community. Structural equation modeling assessed the structure of the causal network and relative importance of factors and processes predicted to drive community invasibility. The linchpin of ecosystem invasibility was the size of and connectivity between basal gaps in perennial vegetation, driven by shifts in the structure and spatial aggregation of the native bunchgrass community. Landscape orientation and soil physical properties determined inherent risk to invasion. Resident bunchgrass and biological soil crust communities provided biotic resistance to invasion by reducing the size of and connectivity between basal gaps and thereby limiting available resources and reducing safe sites for B. tectorum establishment. High levels of cattle grazing reduced ecosystem resilience by reducing native bunchgrass and biological soil crust abundance and altering bunchgrass community composition and facilitated B. tectorum invasion. Conserving and restoring resilience and resistance of these imperiled ecosystems will require reducing cumulative stress levels. As global climate change increases heat and water stress, reducing cumulative cattle grazing intensities by altering utilization rates and/or seasons of use may be the only effective means of accomplishing these goals.
Author: Fiona Claire Schaus Noonan Publisher: ISBN: Category : Big sagebrush Languages : en Pages : 0
Book Description
"Changes in fire regimes, invasive species dynamics, human land use, and drought conditions have shifted important plant species in the Northern Great Basin (NGB)—including big sagebrush (Artemisia tridentata ssp.), conifers (e.g., Juniperus spp.) and invasive annual grasses (e.g., Bromus tectorum). Characterizing how these overlapping disturbances influence species distributions is critical for land management decision-making. Previous research has explored the individual effects of drought, wildfire, restoration, and invasive species on sagebrush steppe communities, but the specific effects of these disturbances in context with one another remain poorly understood at a landscape scale. To address this gap, I constructed multilevel conditional autoregressive (CAR) species distribution models (SDMs) to map the distributions of big sagebrush, juniper, and cheatgrass on lands managed for grazing in the NGB, both with and without a history of fire. These models illuminate the concurrent influences of species co-occurrences, drought, wildfire characteristics (e.g., fire size, time since fire, and number of fires), and restoration treatments. For all SDMs, results indicate that species co-occurrence exhibits the strongest effect—between 1.23 and 19.2 times greater than the next strongest predictor—on all species’ probability of occurrence, suggesting that vegetation co-occurrence meaningfully influences landscape-scale species distributions. In portions of the NGB both with and without historical fire, number of fires and maximum vapor pressure deficit (VPD) also exert substantial influence on the likelihood of species presence, and results indicate that restoration treatments have broadly met desired outcomes for both sagebrush and juniper Narrowing down to only areas that have previously burned, however, models do not support the efficacy of post-fire restoration. All versions of the SDMs, which rely on Bureau of Land Management-administered grazing allotments as a spatial varying intercept, also explicitly point to the differential influence of long-term management regimes on species distributions. These model predictions capture post-disturbance vegetation outcomes under changing fire, climate, and invasive species regimes and in the context of human decision-making, in turn defining a plausible ecological space as these disturbance and management processes play out into the future."--Boise State University ScholarWorks.
Author: National Park National Park Service Publisher: CreateSpace ISBN: 9781492917625 Category : Languages : en Pages : 42
Book Description
The Upper Columbia Basin Network of the National Park Service has identified 14 priority park vital signs, indicators of ecosystem health, which represent a broad suite of ecological phenomena operating across multiple temporal and spatial scales. Our intent has been to monitor a balanced and integrated "package" of vital signs that meets the needs of current park management, but will also be able to accommodate unanticipated environmental conditions in the future. Sagebrush steppe is one particularly high priority vital sign for five UCBN parks: City of Rocks National Reserve (CIRO), Craters of the Moon National Monument and Preserve (CRMO), Hagerman Fossil Beds National Monument (HAFO), John Day Fossil Beds National Monument (JODA), and Lake Roosevelt National Recreation Area (LARO). Sagebrush steppe occupies over 50% of land cover in CIRO, HAFO, and JODA, and over 90% of the vegetated area of CRMO. At LARO, sagebrush steppe is present and significant in the southern half of the park and represents an important park ecosystem. Historic and current land use practices both within and adjacent to UCBN park steppe communities continue to fragment and alter steppe ecosystems, and predicted climate change scenarios for the region will likely exacerbate these changes.
Author: National Park Service Publisher: CreateSpace ISBN: 9781492207375 Category : Nature Languages : en Pages : 30
Book Description
As part of the Upper Columbia Basin Network sagebrush steppe vital signs monitoring program, a survey of sagebrush steppe ecological condition was conducted in late May and early June 2012 within the Clarno Unit of John Day Fossil Beds National Monument (JODA) following methods outlined in the Upper Columbia Basin Network monitoring protocol (Yeo et al. 2009). The plot-based surveys occurred within 3 habitat categories (strata) of vegetation communities.
Author: National Park Service Publisher: CreateSpace ISBN: 9781492207429 Category : Nature Languages : en Pages : 56
Book Description
Monitoring of the condition of sagebrush steppe within the John Day Fossil Beds National Monument (JODA) was conducted in May and June 2011. Four units of the monument were monitored: Clarno, Foree, Painted Hills, and Sheep Rock.
Author: National Park National Park Service Publisher: CreateSpace ISBN: 9781492917663 Category : Languages : en Pages : 68
Book Description
Prior to European colonization, sagebrush steppe covered approximately 44 million ha of the Intermountain West, the vast areas of land between the Rocky Mountains and the Cascades and Sierra Nevada mountain ranges (West and Young 2000). Since then the sagebrush steppe ecosystem has experienced extensive changes (USDA Forest Service 1996, West and Young 2000, Bureau of Land Management 2002, Reid et al. 2002). Substantial portions of the region have been converted to agriculture and development (West and Young 2000, Bunting et al. 2002). Much of the remaining sagebrush steppe has been degraded through overgrazing by livestock, altered fire regimes, and invasion of introduced plants (Reid et al. 2002).
Author: Sienna A. Wessel
Author: Sienna A. Wessel
Author: Michael D. Reisner
Author: Darold W. Sabinske
Author: Fiona Claire Schaus Noonan
Author: National Park National Park Service
Author: National Park Service
Author: 
Author: National Park Service
Author: National Park National Park Service
Author: Jessica Ann Robinson