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We developed a framework for identifying which biotic traits would provide the best initial indication of longer-term target restoration goals and applied the framework to restoration drill-seedings of deep-rooted perennial bunchgrasses (DRPBGs) used to rehabilitate and restore semiarid rangelands threatened by exotic annual grasses (EAGs, e.g. cheatgrass) and the recurrent wildfire that EAGs cause. Initial traits measured included cover, basal diameter, height, and density (#plants/area) of DRPBGs and cover of EAGs and Sandberg bluegrass (Poa secunda, POSE, a disturbance-adapted perennial). The longer-term target objective was ≥25 % DRPBG cover and ≤13 % EAG cover by the 5th year following drill-seedings. Measurements were made on 112 plots spanning 113,000 ha in sagebrush steppe on the Soda wildfire scar, in the Northern Great Basin, USA. Traits of DRPBGs tended to be uncorrelated with one another, thus each was informative in describing vegetation condition. Where DRPBG cover was initially >17 %, it tended to become >25 % by the 5th-year post-seeding. In plots that overcame an initial risk of not meeting the target objective (i.e. <17 % initial DRPBG cover), DRPBG tended be large DRPBGs (>22.8 cm height) and plots also had >7 % cover of POSE. Additional “sets” of initial vegetation traits were also predictive of longer-term restoration success or failure. Restoration drill-seeding of DRPBGs is a key but varied-outcome tool for breaking the exotic grass-fire cycle, and, contrary to a conventional tendency to rely on a limited number of mean traits such as % cover, a suite of biotic traits appears necessary to monitor to reliably know if trials are likely to yield success.
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Climate change shifts ecosystems, altering their compositions and instigating transitions, making climate change the predominant driver of ecosystem instability. Land management agencies experience these climatic effects on ecosystems they administer yet lack applied information to inform mitigation. We address this gap, explaining ecosystem shifts by building relationships between the historical locations of 22 ecosystems (c. 2000) and abiotic data (1970–2000; bioclimate, terrain) within the southwestern United States using ‘ensemble’ machine learning models.
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We used data from a 5-year grazing experiment in the Northern Great Plains of the US. We tested whether grazing management treatments affect SIC, and whether grazing-induced SOC accrual was potentially offset by SIC loss. The experiment had a randomised complete block design and pretreatment data. Response variables were SOC and SIC stocks (0–60 cm depth). Moderate summer grazing (control) is regionally common and treatments that may alter soil stocks included: no grazing, severe summer grazing, moderate autumn grazing, and severe autumn grazing. We also tested for a negative relationship between SOC and SIC across all soil cores (n = 244). Severe grazing (summer and autumn) increased SOC by 0.83 and 0.88 kg × m−2 relative to moderate summer grazing, respectively. However, no treatments affected SIC. Conversely, we found an overall weak but significant (r2 = 0.04, P = 0.002), near one-to-one negative relationship between SIC and SOC stocks of soil cores. Our findings suggest severe grazing can increase SOC without affecting SIC, at least over the short term (5 years). This finding mirrors results from an observational study elsewhere in the Northern Great Plains that also failed to detect grazing effects on SIC. Long-term grazing experiments (>5 years) with pretreatment data may be required to detect grazing effects on SIC.
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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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Forest recovery was generally associated with cooler, mesic sites in proximity to forested refugia; shifts toward scrub and grassland types were most common in warmer, dryer locations distant from forested refugia. Under future climate scenarios, models project decreases in postfire forest recovery and increases in nonforest vegetation. However, forest to nonforest conversion was partially offset under a scenario of reduced burn severity and increased retention of forested refugia, highlighting important management opportunities. Burning trends in the southwestern United States suggest that postfire vegetation will occupy a growing landscape fraction, compelling renewed management focus on these areas and paradigm shifts that accommodate ecological change. I illustrate how management decisions around resisting, accepting, or directing change could be informed by an understanding of processes and patterns of postfire community variation and likely future trajectories.
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We evaluated the responses of forest structure, regeneration, old-tree mortality, and tree growth to forest restoration for 21 years in a landscape-scale (2114 ha) experiment in a ponderosa pine-Gambel oak forest in northern Arizona, United States. Relative to the start of the experiment in 1996, tree density and basal area (BA) in the treated area were reduced by 56 and 38%, respectively, at the end of the study period compared to the untreated control. Conifer seedling densities generally declined and sprouting hardwoods increased following treatment. Mortality of old oak trees was significantly higher in the treated area compared to the control, likely due to fire-caused injury during the prescribed burning. Mean annual BA increment of individual trees was 93% higher in the treated area than in the control. Our study provides new information on ponderosa pine forest responses to restoration treatments at broad spatial scales and under realistic operational conditions. Results from this study can help inform landscape-scale restoration projects in dry, fire-dependent forests.
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To evaluate forest restoration and fuel treatment benefits and costs, we conducted a meta-analysis of benefit-cost ratios for restoration benefit types documented in the literature for Western U.S. dry mixed conifer forests at risk of uncharacteristic wildfires. A total of 120 observations were collated from 16 studies conducted over the last two decades, with benefits ranging from enhanced ecosystem services to extensively avoided wildfire costs. Significant variation in the value of restoration and fuel treatment benefit types was found, indicating that restoration benefits differ in value based on societal importance. Overall, 17 individual benefit types were aggregated to show that in the most valuable and at-risk watersheds, every dollar invested in forest restoration can provide up to seven dollars of return in the form of benefits and provide a return-on-investment of 600%.
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Scaling up climate-adaptation in wildfire-prone watersheds requires innovative partnerships and funding. Water utilities are one stakeholder group that could play a role in these efforts. The overarching purpose of this study was to understand water utility engagement in wildfire mitigation efforts in the western United States. We conducted an online survey of water utilities in nine states and received 173 useable responses. While most (68%) respondents were concerned or very concerned about future wildfire events and the impact of wildfire on their operations, only 39% perceived their organization as responsible for mitigating wildfire risk. Federal land ownership decreased feeling responsible for wildfire mitigation, while concern for and information on wildfire increased feeling responsible for mitigation. The perception of response efficacy of mitigation actions for the 68 water utilities engaged in wildfire risk mitigation activities was very high, with most agreeing that mitigation actions are effective. Self-efficacy to implement mitigation actions, however, was mixed, with most utilities wanting more information on wildfire risk and impacts to watershed services. The most reported wildfire mitigation actions were forest thinning and stream restoration. Water utilities engaging in these actions typically partnered with government agencies or other water utilities to complete the work and funded these activities through water user fees and grants. Our findings suggest that water utility engagement in wildfire mitigation for water security could be increased through providing more assessments of wildfire risk to water utilities and through more outreach and engagement with water utilities operating on federal lands.
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Changes to US wildfire policy in 2009 blurred the distinction between fires managed for resource benefits and fires with primarily suppression objectives, making management strategies difficult to track. Here, qualitative text is coded from a sample of 282 Wildland Fire Decision Support System Relative Risk Assessments completed on wildfires between 2010 and 2017 to examine the prevalence of different strategies and their associations with risk. Suppression is used most, associated with high risk. Managers discuss intent to suppress even when it is untenable. Monitoring, confine, or point protection are used much less commonly and when risk is low. The Southwest region discusses a diversity of strategies, leveraging landscape barriers from past management to support them; the Northwest discusses suppression or monitoring and rarely links strategy selection to barriers. Based on associations between physical barriers to fire spread, risk, and strategy, creating more barriers may provide a path forward to better implement fire policy.
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In this white paper, we assert that the current wildfire management approach has partially inverted the wildfire problem as one in which wildland fires encroach on communities when, in actuality, it is communities that have increasingly impinged on wildlands where fires might appropriately play an important ecological role. As a result, predominant strategies continue to apply shortsighted, risk-averse reactions emphasizing community protection at the expense of creating resilient landscapes and promoting safe and effective wildfire responses. In doing so, managers are inadvertently limiting agency ability to build fire-adapted communities and generate landscape vegetation and fire conditions that support more meaningful and useful change.