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In response to large, severe wildfires in historically fire-adapted forests in the western US, policy initiatives, such as the USDA Forest Service’s Collaborative Forest Landscape Restoration Program (CFLRP), seek to increase the pace and scale of ecological restoration. One required component of this program is collaborative adaptive management, in which monitoring data are used to iteratively evaluate and improve future management actions. Here, we assess the success of seven CFLRP treatments, implemented on 2,300 ha during the first three years of the Colorado Front Range Landscape Restoration Initiative (LRI) at achieving desired forest structure by comparing pre- and post-treatment conditions. We also compare post-treatment conditions with reconstructions of historical (ca. 1860) forest conditions to contextualize the magnitude of treatment effects. Restoration projects moved stands toward desired conditions by reducing basal area, tree density, and canopy cover and increasing average tree diameter, large gap cover, and abundance of small- to medium-sized tree groups. Post-treatment stands were similar to historical stands with respect to basal area of ponderosa pine; however, they had higher total tree density and fewer gaps than historical reference conditions, suggesting that restoration prescriptions may be improved with increased flexibility for density reduction of Douglas-fir and increased gap creation. This examination of early CFLRP treatment outcomes as they relate to desired conditions informs potential areas of adjustments to future treatments and provides baseline data to evaluate the evolution of treatments over the program’s lifespan. We also identify and discuss several scientific, social, and logistical constraints to large-scale restoration success and make several recommendations to improve restoration outcomes. [ABSTRACT FROM AUTHOR]

In recent years, increased wildfire activity and climate change have raised concern among scientists and land managers regarding current and future vegetation patterns in post-burn landscapes. We surveyed conifer regeneration 8-15 years after fire in six burn areas in the lower montane zone of the Colorado Front Range. We sampled across a broad range of elevations, aspects, and fire severities and found that densities of ponderosa pine ( Pinus ponderosa) and Douglas-fir ( Pseudotsuga menziesii) are generally low, although areas of abundant regeneration do occur. Conifer regeneration was most limited in xeric settings, including more southerly aspects and elevations closer to lower treeline. Additionally, fewer juvenile conifers occurred at greater distances from mature, live trees indicating that seed source as well as topoclimatic setting limits post-fire tree regeneration. Projecting the extent of future forest cover is uncertain due to the possibility of future pulses of tree establishment and unknown depletion rates of existing seedling populations. However, current patterns of post-fire seedling establishment suggest that vegetation composition and structure may differ notably from historic patterns and that lower density stands and even non-forested communities may persist in some areas of these burns long after fire, especially in xeric settings or where no nearby seed source remains. [ABSTRACT FROM AUTHOR]

Question: What is the relative importance of low- and highseverity fires in shaping forest structure across the range of Pinus ponderosa in northern Colorado? Location: Colorado Front Range, USA. Methods: To assess severities of historic fires, 24 sites were sampled across an elevation range of 1800 to 2800 m for fire scars, tree establishment dates, tree mortality, and changes in tree-ring growth. Results: Below 1950 m, the high number of fire scars, scarcity of large post-fire cohorts, and lack of synchronous tree mortality or growth releases, indicate that historic fires were of low severity. In contrast, above 2200 m, fire severity was greater but frequency of widespread fires was substantially less. At 18 sites above 1950 m, 34 to 80% of the live trees date from establishment associated with the last moderate- to highseverity fire. In these 18 sites, only 2 to 52% of the living trees pre-date these fires suggesting that fire severities prior to any effects of fire suppression were sufficient to kill many trees. Conclusions: These findings for the P. ponderosa zone above ca. 2200 m (i.e. most of the zone) contradict the widespread perception that fire exclusion, at least at the stand scale of tens to hundreds of hectares, has resulted in unnaturally high stand densities or in an atypical abundance of shade-tolerant species. At relatively mesic sites (e.g. higher elevation, north-facing), the historic fire regime consisted of a variable-severity regime, but forest structure was shaped primarily by severe fires rather than by surface fires. [ABSTRACT FROM AUTHOR]

We examined patterns of non-native plant diversity in protected and managed ponderosa pine/Douglas-fir forests of the Colorado Front Range. Cheesman Lake, a protected landscape, and Turkey Creek, a managed landscape, appear to have had similar natural disturbance histories prior to European settlement and fire protection during the last century. However, Turkey Creek has experienced logging, grazing, prescribed burning, and recreation since the late 1800s, while Cheesman Lake has not.Using the modified-Whittaker plot design to sample understory species richness and cover, we collected data for 30 0.1 ha plots in each landscape. Topographic position greatly influenced results, while management history did not. At both Cheesman Lake and Turkey Creek, low/riparian plots had highest native and non-native species richness and cover; upland plots (especially east/west-facing, south-facing and flat, high plots) had the lowest. However, there were no significant differences between Cheesman Lake and Turkey Creek for native species richness, native species cover, non-native species richness, or non-native species cover for any topographic category. In general, non-native species richness and cover were highly positively correlated with native species richness and/or cover (among other variables). In total, 16 non-native species were recorded at Cheesman Lake and Turkey Creek; none of the 16 non-native species were more common at one site than another.These findings suggest that: (1) areas that are high in native species diversity also contain more non-native species; (2) both protected and managed areas can be invaded by non-native plant species, and at similar intensities; and (3) logging, grazing, and other similar disturbances may have less of an impact on non-native species establishment and growth than topographic position (i.e., in lowland and riparian zones versus upland zones). [Copyright &y& Elsevier]

Climate warming is contributing to increases in wildfire activity throughout the western United States, leading to potentially long‐lasting shifts in vegetation. The response of forest ecosystems to wildfire is thus a crucial indicator of future vegetation trajectories, and these responses are contingent upon factors such as seed availability, interannual climate variability, average climate, and other components of the physical environment. To better understand variation in resilience to wildfire across vulnerable dry forests, we surveyed conifer seedling densities in 15 recent (1988–2010) wildfires and characterized temporal variation in seed cone production and seedling establishment. We then predicted postfire seedling densities at a 30‐m resolution within each fire perimeter using downscaled climate data, monthly water balance models, and maps of surviving forest cover. Widespread ponderosa pine (Pinus ponderosa) seed cone production occurred at least twice following each fire surveyed, and pulses of conifer seedling establishment coincided with years of above‐average moisture availability. Ponderosa pine and Douglas‐fir (Pseudotsuga menziesii) seedling densities were higher on more mesic sites and adjacent to surviving trees, though there were also important interspecific differences, likely attributable to drought and shade tolerance. We estimated that postfire seedling densities in 42% (for ponderosa pine) and 69% (for Douglas‐fir) of the total burned area were below the lowest reported historical tree densities in these forests. Spatial models demonstrated that an absence of mature conifers (particularly in the interior of large, high‐severity patches) limited seedling densities in many areas, but 30‐yr average actual evapotranspiration and climatic water deficit limited densities on marginal sites. A better understanding of the limitations to postfire forest recovery will refine models of vegetation dynamics and will help to improve strategies of adaptation to a warming climate and shifting fire activity. [ABSTRACT FROM AUTHOR]

Tree age and size structures were compared within and among topographic categories in portions of a 35-km2 unlogged landscape and a comparable adjacent logged landscape. Tree density was generally higher in the logged landscape. One fifth of plots in the unlogged landscape had trees older than 400 years, but no trees older than 400years remained in the logged landscape plots. Ten recruitment pulseswere identified for the unlogged study area, accounting for 49% of all trees measured during 26% of the 421-year survival record. Recruitment pulses in the logged area accounted for fewer trees during a larger amount of time. Most recruitment periods in the unlogged landscape coincided with known past major fires. The mixed-severity historical fire regime created openings that persisted for as long as 148 years. The following components exist in the unlogged landscape: (i) forest patches having a distinct age cap reflecting regeneration following an earlier stand-replacing fire, (ii) uneven-aged forest patches having no evidence of an age cap, (ii) openings created by fire, and (iv) riparian areas. Results suggest that the logged landscape is poised to regain an old-growth age distribution, and tree removal in the logged landscape could restore the size distribution found in the unlogged landscape. However, the unlogged landscape has openings not found in the logged landscape that should be considered in restoration efforts at a landscape scale. [ABSTRACT FROM AUTHOR]