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Quaking aspen ( Populus tremuloides ) is the most widespread tree species in North America and has supported a unique ecosystem for tens of thousands of years, yet is currently threatened by dramatic loss and possible local extinctions. While multiple factors such as climate change and fire suppression are thought to contribute to aspen’s decline, increased browsing by elk ( Cervus elaphus ), which have experienced dramatic population increases in the last ∼80 years, may severely inhibit aspen growth and regeneration. Fires are known to favor aspen recovery, but in the last several decades the spatial scale and intensity of wildfires has greatly increased, with poorly understood ramifications for aspen growth. Here, focusing on the 2000 Cerro Grande fire in central New Mexico – one of the earliest fires described as a “mega-fire” - we use three methods to examine the impact of elk browsing on aspen regeneration after a mega-fire. First, we use an exclosure experiment to show that aspen growing in the absence of elk were 3× taller than trees growing in the presence of elk. Further, aspen that were both protected from elk and experienced burning were 8.5× taller than unburned trees growing in the presence of elk, suggesting that the combination of release from herbivores and stimulation from fire creates the largest aspen growth rates. Second, using surveys at the landscape level, we found a correlation between elk browsing intensity and aspen height, such that where elk browsing was highest, aspen were shortest. This relationship between elk browsing intensity and aspen height was stronger in burned ( r = −0.53) compared to unburned ( r = −0.24) areas. Third, in conjunction with the landscape-level surveys, we identified possible natural refugia, microsites containing downed logs, shrubs etc. that may inhibit elk browsing by physically blocking aspen from elk or by impeding elk’s ability to move through the forest patch. We did not find any consistent patterns between refuge elements and aspen size or canopy cover suggesting that natural refugia are not aiding in aspen recruitment and that all young aspen were susceptible to browsing. In much of their normal range, aspen are not growing to large size classes, which threatens the future of this iconic species and calls into question the ability of ecosystems to recover from mega-fires. Our results highlight the importance of considering multiple interacting factors (i.e. fire and increased elk browsing) when considering aspen management and regeneration. [ABSTRACT FROM AUTHOR]

Landscape-scale wildfire has occurred in higher frequencies across the planet. Fuel reduction treatments to fire-adapted systems have been shown to reduce the impact to human values-at-risk. However, few studies have examined if these treatments contribute to ecosystem resilience, or the capacity of a system to absorb perturbation and return to a similar set of structures or processes. We defined short-term metrics of resiliency to test the hypothesis that fuel reduction treatments in mixed conifer forests increased a fire-adapted system’s resiliency to uncharacteristically severe wildfire. In addition, we tested the hypothesis that fuel reduction treatments reduced burn severity, thereby increasing protection for adjacent human communities. We examined a mixed conifer forested landscape in the southwestern U.S. that was burned by a landscape-scale “mega-fire” in 2011; fuel reduction treatments had been established around communities in the 10 years prior to the fire. Fire effects were highly variable in both treated and untreated forests. However, analysis of resiliency metrics showed that: (a) treated units retained a higher proportion of large trees and had post-fire tree densities within the natural range of variability; (b) the understory herbaceous community had significantly higher cover of native grasses in the treated units, but no significant differences in nonnative cover between treated and untreated units; and (c) high-severity patch sizes were significantly larger in untreated stands and covered a larger proportion of the landscape than historical reference conditions. Fire severity, as defined by overstory mortality and basal area loss, was significantly lower in treated units; on average, trees killed per hectare in untreated units was six times the number of trees killed in treated units. Fuel reduction treatments simultaneously reduced fire severity and enhanced short-term metrics of ecosystem resiliency to uncharacteristically severe fire. [ABSTRACT FROM AUTHOR]

Highlights: [•] Unburnt patches within wildfire boundaries are potential biotic refuges. [•] Within a eucalypt forest wildfire, unburnt patches comprised 1% of the landscape. [•] Most patches arose due to microclimate, but some resulted from prior burning. [•] The refuge quality of a patch is influenced by the mechanism of its occurrence. [•] In variable landscapes potential refuges will occur without management intervention. [ABSTRACT FROM AUTHOR]

Abstract: LANDFIRE is the working name given to the Landscape Fire and Resource Management Planning Tools Project (http://www.landfire.gov). The project was initiated in response to mega-fires and the need for managers to have consistent, wall-to-wall (i.e., all wildlands regardless of agency/ownership), geospatial data, on vegetation, fuels, and terrain to support use of fire behavior and effects prediction systems in guiding policy and management decisions. Base layers were created in a 5-year program of research and development ending in 2009, with processes in place to periodically update fuel and vegetation layers in response to anthropogenic and natural disturbances. LANDFIRE has been institutionalized as the primary data source for modeling activities aimed at meeting the goals of the United States’ National Cohesive Wildland Fire Management Strategy, and the data are available on-line to any user for conducting landscape analyses. Data access and use are high and expected to grow with the increasing scope and complexity of wildland fire management, thus requiring continued LANDFIRE improvements and updates. [Copyright &y& Elsevier]

Abstract: Central Yunnan, China was once dominated by evergreen broad-leaved forests. After a long period of destructive exploitation including agriculture development, overlogging for timber and cutting for fuelwood, these forests are being allowed to reestablish themselves. A large area is now dominated by the conifer Pinus yunnanensis forest which has naturally regenerated and represents an early intermediate stage in the reestablishment of the evergreen broad-leaved forest. In 2006, a mega-fire burned approximately 18.49km2 of this forest. The Pinus is growing back. To examine the process of regeneration dynamics and recovery of the Pinus community after the mega-fire, we investigated plant communities in burned and unburned areas, including a P. yunnanensis shrubland regenerated after the fire, a P. yunnanensis forest without fire occurrence, a P. yunnanensis and Lithocarpus mairei mixed forest, and a Castanopsis orthacantha and Lithocarpus dealbatus evergreen broad-leaved forest, as well as a plantation of P. yunnanensis. Abundant seedlings and saplings of P. yunnanensis and some light-demanding deciduous and evergreen broad-leaved tree species were found in the Pinus shrubland five years after the fire. The frequency distribution by height-classes after the fire was of an inverse-J type, representing very good regeneration. We used space-for-time substitution to obtain an understanding of the directions and pathways of the succession. The approximate successional trend in the area was from the Pinus shrubland to the Pinus forest, then to the mixed coniferous and evergreen broad-leaved Pinus–Lithocarpus forest, then to the evergreen broad-leaved Castanopsis–Lithocarpus forest. In the early successional stage, the floristic richness and species diversity of the Pinus shrubland had lower values as compared to those in the middle and late successional stages, but much higher than those of the Pinus plantation. Our results indicate that the natural recovery of P. yunnanensis after the fire was more efficient than that of a man-made forest of the same species. Nature’s process outpaced human intervention. [Copyright &y& Elsevier]