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Significant and lasting soil carbon change in rangeland ecosystems requires ecological state change. Although within-ecological state, soil carbon dynamics can occur, they are driven primarily by short-term fluctuations in weather, specifically precipitation, and are insufficient to provide reliable estimates of change to support policy and management decisions. Changes in grazing management typically do not result in ecological state change, apart from the vegetation structural change associated with long-term overgrazing. Dominant vegetation attributes such as shrub-to-grass ratios, cool season versus warm season plant production, and annual versus perennial growth habit define ecological state and are detectable accurately and cost-effectively using existing remote-sensing technology. These vegetation attributes, along with stationary soil properties, allow for mapping at scales consistent with a variety of policy and management decisions and provide a logical basis for developing a credible sampling framework for verification. Furthermore, state-transition models of ecological state dynamics are designed to provide information that can be used to support inventories and management decisions for soil carbon and other ecosystem services.
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We continued to monitor streamflow and precipitation at an existing hydrologic monitoring network at the Grizzly Creek Fire, CO. Through analysis of this long-term dataset, managers may better plan for infrastructure impacts multiple years post-fire. Next, to evaluate the performance of existing post-fire decision criteria and assess potential improvements, we developed the Post-fire Decision Criteria Assessment Framework. We applied this framework to the Grizzly Creek Fire, CO (2020) and specifically evaluated the decision criteria for highway safety closures applied by the Colorado Department of Transportation (CDOT) to Interstate (I-) 70 within Glenwood Canyon, CO between Dotsero and Glenwood Springs in the first three years post-fire (2021-2023). We defined the infrastructure impact (referred to as ‘impact’) as any instance where I-70 was closed by the Colorado Department of Transportation beyond the end of the precipitation event for maintenance or cleanup associated with flooding or sediment. We
identified a total of 20 safety closure decisions reported by CDOT over the study period and classified each decision into one of three performance categories: true positive (preemptive closure and impact occurred), false positive (preemptive closure and no impact occurred), and false negative (no preemptive closure but impact occurred, resulting in emergency closure). We found that the performance of the safety closure decision criteria varied over the study period in alignment with the Colorado Department of Transportation’s aim of protecting travelers’ safety while reducing unnecessary safety closures without impact. Decisions that resulted in compromised traveler safety or unnecessary closures were considered poor performance. We identified that precipitation-based metrics including precipitation event depth and short-term intensity (i.e. 15-minute) were significant indicators of impact to I-70. Soil moisture-based metrics may be a good secondary indicator but further analysis with a larger dataset is needed. This framework is applicable across burned watersheds and to other infrastructure impacts of interest, such as for water intake shutdown.
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Our results underscore the importance of active and comprehensive management actions immediately following wildfire (i.e., seeding coupled with planting sagebrush), that might offset short-term impacts of wildfire by timing rapid recovery of sagebrush to meet short-term species’ habitat requirements. Burned leks likely have substantial immediate impacts that may extend beyond wildfire boundaries, especially if critical source habitats are removed. Such impacts could fragment habitat and disrupt connectivity, thereby affecting larger populations and possibly contributing to more widespread declines in sage-grouse populations.
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This study measured aboveground C pools and fluxes at leaf, soil, and ecosystem scales over a single growing season in plots that had 200 mm of supplemental precipitation added in either winter or summer for the past 21 years, in shrub- and exotic-bunchgrass-dominated garden plots. In general, ecosystem C uptake and long-term biomass accumulation were greater in winter- and summer-irrigated plots compared to control plots in both vegetation communities.
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The Nature Conservancy and the Forest Service, Department of Agriculture have long-term goals to reintroduce fire into U.S. ecosystems at ecologically relevant spatial and temporal scales. Building on decades of collaborative work, a Master Participating Agreement was signed in March 2017 to increase overall fire management capacity through training and education. In October 2017, The Nature Conservancy hosted a cross-boundary fire training, education, research, and restoration-related event for 2 weeks at Sycan Marsh Preserve in Oregon. Eighty people from 15 organizations applied prescribed fire on over 1,200 acres (490 ha). Managers and scientists participated
in the applied learning and training exercise. The exercise was a success; operational and research objectives were met, as indicated by multiagency, multidisciplinary fire research, and effectiveness monitoring. This paper describes a paradigm shift of fire-adapted, cross-boundary, multiagency landscape-scale restoration. Participants integrated adaptive management and translational ecology so that applied controlled burning incorporated
the most up-to-date scientifically informed management decisions. Scientists worked with practitioners to advance their understanding of the challenges being addressed by managers. The model program has stimulated an exponential increase in landscape scale and ecologically relevant dry forest restoration in eastern Oregon. Collaboration between managers and scientists is foundational in the long-term success of fire-adapted restoration. Examples of effects of prescribed fire on ecosystem services in the project area, such as increased resilience of trees in drought years, are also provided.
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Accurate drought assessments are critical for mitigating the deleterious impacts of water scarcity on communities across the world. In many regions, deficits in soil moisture represent a key driver of drought conditions. However, relationships between soil moisture and widely used drought indicators have not been thoroughly evaluated. In addition, there has not been an in‐depth assessment of the accuracy of operational soil moisture models used for drought monitoring. Here, we used 2,405 observed time series of soil moisture from 637 long‐term monitoring stations across the conterminous United States to test the ability of meteorological drought indices and soil moisture models to accurately characterize soil moisture drought. The optimal timescales for meteorological drought indices varied substantially by depth, but were ~30 days for depth averaged conditions; progressively longer timescales (∼10-80 days) represent progressively deeper soil moisture (2-36 in.). However, soil moisture models (including Short‐term Prediction Research and Transition Center, Soil Moisture Active Passive L4, and Topofire) significantly outperformed the meteorological drought indices for predicting standardized soil moisture anomalies and drought conditions. Additionally, soil moisture models represent near instantaneous conditions, implicitly aggregating antecedent data thereby eliminating the need for timescales, providing a more effective and convenient method for soil moisture drought monitoring. We conclude that soil moisture models provide a straightforward and favorable alternative to meteorological drought indices that better characterize soil moisture drought.
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Biocrusts are sensitive to changes in livestock grazing intensity in arid rangelands and may be useful indicators of ecosystem functions, particularly soil properties like soil stability, which may suggest the potential for soil erosion. We compared biocrust community composition and surface soil stability in a big sagebrush steppe rangeland in the northwestern Great Basin in several paired sites, with or without long-term cattle grazing exclusion, and similar soils (mostly sandy loams), climate, and vegetation composition. We found that livestock grazing was associated with both lower surface soil stability and cover of several biocrust morphogroups, especially lichens, compared with sites with long-term livestock exclusion. Surface soil stability did not modify the effects of grazing on most biocrust components via interactive effects. Livestock grazing effects on total biocrust cover were partially mediated by changes in surface soil stability. Though lichens were more sensitive to grazing disturbance, our results suggest that moss (mostly Tortula ruralis in this site) might be a more readily observable indicator of grazing-related soil stability change in this area due to their relatively higher abundance compared with lichens (moss: mean, 8.5% cover, maximum, 96.1%, lichens: mean, 1.0% cover, maximum, 14.1%). These results highlight the potential for biocrust components as sensitive indicators of change in soil-related ecosystem functions in sagebrush steppe rangelands. However, further research is needed to identify relevant indicator groups across the wide range of biocrust community composition associated with site environmental characteristics, variable grazing systems, other rangeland health metrics, and other disturbance types such as wildfire.
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Pre-fire differences in fuel and vegetation responses among treatments largely did not persist or were not detectible 1 to 2 years following wildfire. These findings suggest that the extreme wildfire conditions superseded long-term treatment differences in many fuel and vegetation metrics observed prior to wildfire. Despite subtle treatment differences, the hand thinned treatment resulted in the lowest change in fuel loading relative to all other treatments. Lastly, pre-fire differences in exotic species among fuel treatments were retained following wildfire, suggesting some treatments may have greater potential for exotic species expansion or type conversion to exotic grasslands.
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We focused on three metrics that are important for forest management objectives for the area: forest carbon storage, area burned at high severity, and total area burned by wildfire. Management explained a substantial amount of variance in the short term for area burned at high severity and longer term carbon storage, while climate explained the most variance in total area burned. Our results suggest that simulated extensive management activities will not meet all the desired management objectives. Both the extent and intensity of forest management will need to increase significantly to keep pace with predicted climate and wildfire conditions.
Ensuring the availability of adequate seed supplies of species and sources appropriate for restoration projects and programs necessitates extensive science‐based planning. The selection of target species requires a review of disturbance conditions and reference areas, development of a reference model, and consideration of specific objectives, timeframes, available resources, and budgets as well as the performance of prospective species in past restoration efforts. Identification of seed sources adapted to site conditions is critical to provide for short‐term establishment and long‐term sustainability. Seed zones and plant movement guidelines provide tools for sourcing plant materials with reduced risk of maladaptation. A seed zone framework also facilitates seed use planning and contributes to stability and predictability of the commercial market, thereby reducing costs and improving the availability of adapted seed supplies. Calculating the amount of seed required for each species is based on seed quality (viability, purity), seed weight, expected seedling establishment, and desired composition of the seeding. If adequate collections from wildland stands are not feasible, then seed increase in seed fields or use of nursery stock may be warranted. Adherence to seed collection and seed production protocols for conserving genetic diversity is critical to protect genetic resources and buffer new seedings and plantings against environmental stressors. Maintenance of genetic diversity becomes even more critical considering current or expected climate change impacts. Collaboration and partnerships can benefit seed selection and procurement programs through sharing of information, coordination in project planning, and increasing the availability of native seed.