Impact of Thinning Strategy, Surface Fuel Loading and Burning Conditions on Fuel Treatment Efficacy in Ponderosa Pine Dominated Forests of the Southern Rocky MountainsZiegler, Justin Paul; Hoffman, Chad M.; Tinkham, Wade T.; Parsons, Russell A.; Battaglia, Mike A.; Menakis, James
doi: 10.1007/s44391-025-00034-8pmid: N/A
Managers across the western US seek effective fuel treatment strategies to mitigate hazardous fuel loads and risks of high severity fire in dry conifer forests. Conventional fuel hazard reduction treatments emphasis reducing canopy fuel continuity and surface fuel loading using an even spaced, thin-from-below approach, with pile or broadcast burning of residual surface fuels. Such treatments often result in forest structures that differ from the historical conditions. Ecological restoration treatments emphasize enhancing structural heterogeneity but may produce less fire-resistant stands causing tradeoffs between fuel hazard reduction and restoration objectives. This study explored these tradeoffs by simulating thinning treatments on ponderosa pine sites, spanning several levels of basal areas, horizontal and vertical distributions of canopy fuels, surface fuel loads, fuel moistures and wind speeds. All types of thinning reduced fire behavior and severity relative to untreated forests. Fire rate of spread was slightly increased following variable retention harvests or treatment that included thinning from below. Fire weather, cutting methods, and surface fuel load all influenced potential fire severity. Variable retention thinnings did not reduce severity as much as treatments including a thin-from-below, regardless of the horizontal arrangement of trees. Our results suggest tradeoffs between ecological restoration and hazard reduction could be overcome if restoration treatments incorporate small tree removal. Overstory removal combined with reductions in surface fuel loading, through prescribed fire or other means, were more effective than either overstory or surface fuel reductions alone.
Whole Stand Yield and Density Equations for the Basswood Forest Type in the Lake StatesHeikes, Daniel D.; Gifford, Tyler S.; Zobel, John M.
doi: 10.1007/s44391-025-00036-6pmid: N/A
Whole stand yield models serve forest managers by providing projections of useful stand metrics such as height and volume. Climate shifts are currently being observed in the Lake States, including changes in forest composition and species’ ranges. Basswood (Tilia americana L.) has potential to become a climate winner but lacks whole stand yield model parameters to adequately predict forest conditions. This paper aims to extend the utility of an existing whole stand yield model to basswood dominated stands in the Lake States to enable adaptation to shifting climatic conditions. Basal area, quadratic mean diameter, trees per acre, volume, and height models were fit using nonlinear least squares estimation. Models were validated with cross-validation, independent stand inventory data collected from a local forest management area, and national forest inventory data from more southerly states to evaluate model performance under climate conditions the Lake States could see in the future. Fit statistics for these models were consistent with other modeling efforts in the region, and validation statistics showed applicability of the models to broad basswood ranges and potential stability under changing climates. Forest managers can now utilize these new yield models to improve current and future management of the increasingly important basswood forest type.
Predicting Soil Temperatures Associated with Reintroduction of Prescribed Burning in Western Coniferous ForestsWeise, David R.; Sackett, Stephen S.; Haase, Sally M.; Johnson, Nels; Burke, Gloria M.
doi: 10.1007/s44391-025-00037-5pmid: N/A
Elevated soil temperatures resulting from reintroduction of prescribed fire into long unburnt stands have been associated with unintended tree mortality. Several models exist to predict soil temperatures resulting from soil heating by fire; however, data to develop and validate these models are limited. A model to predict soil temperature at depths up to 25 inches (0.63 m) was developed from a data set from 46 prescribed burns in coniferous forests in national forests and parks in Arizona and California. Soil temperature was less than 140 °F (60 °C) at depths greater than 6 inches (0.15 m) and constant below 10 inches (0.25 m). Using a Bayesian generalized nonlinear additive model, nine models formed from combinations of soil and humus moisture contents, fuel consumption and tree species were fit to soil temperature data for Pinus ponderosa, P. lambertiana, and Sequoiadendron gigantea. Bayesian R2 for the full model and the reduced model containing tree species and fuel consumption was 0.70 and 0.67, respectively. The Bayesian model predicted higher maximum temperatures than two soil heating models in the First Order Fire Effects Model. Based on parsimony, the model using fuel consumption and tree species is recommended for use.
Mapping Community Capacity to Reduce Vulnerability to Wildfire in Colorado, USACourtney, Karissa; Holm, Federico; Brousseau, Jennifer; Walker, Sarah E.; Cheng, Antony S.; Hamilton, Matthew; Nielsen-Pincus, Max; Toman, Eric; Salerno, Jonathan
doi: 10.1007/s44391-025-00038-4pmid: N/A
Communities can face significant risk from wildfire, often compounded by climate change and legacies of industrial forest management. Policies and collaborative approaches for managing wildfire risk have evolved to include greater roles and responsibilities for these communities, yet local communities often lack the capacity to plan and implement actions to reduce risk of, respond to, and recover from wildfire. In this paper, we explore spatial patterns of local capacity relative to wildfire risk across the state of Colorado, USA, with the aim of informing efforts to reduce vulnerability. Significant resources are directed toward modeling and mapping wildfire risk at such policy-relevant scales, but complementary representations of local capacity are largely lacking. We use publicly available data, weighted by perceptions from wildfire scientists and practitioners, to create an index of local capacity. Results highlight variable geographic distribution of local capacity, including notable disparities with respect to wildfire risk. While the importance of funding is well documented, results show how local residents and managers may be able to leverage different strengths both in the presence and absence of external funding to respond to wildfire risks. Conclusions inform policy and management in efforts to direct funding and support to local communities most vulnerable to wildfire, while acknowledging that different communities have varying needs.
Carbon Sequestration and Forest Rotation Age: A Meta-RegressionNing, Zhuo; Chen, Van; Sun, Changyou
doi: 10.1007/s44391-025-00039-3pmid: N/A
Forest carbon sequestration has gained global attention as an effective nature-based strategy for mitigating climate change, with optimal harvest rotation decisions directly affecting carbon storage outcomes. This meta-regression synthesizes 59 primary studies to assess the impact of economic, ecological, and methodological factors on forest rotation ages. Using weighted least squares (WLS), fixed-effects, and random-effects models, we find that the fixed-effects model offers the most robust estimates. Results reveal that higher carbon prices consistently extend rotation periods, while higher discount rates reduce them. Assumptions like stochastic timber pricing, one-time carbon payments, and carbon-release penalties generally prolong rotations, whereas product decay and thinning shorten them. Insignificant variables, such as bioenergy use, monitoring costs, and ecosystem services, may reflect limited study coverage or context-specific effects. These findings underscore the importance of flexible modeling assumptions and context-sensitive policy designs, suggesting that future research should investigate harvesting rotations under bioenergy and carbon monitoring cost considerations.
Comparing Juvenile Physiology and Morphology of Two High-Elevation Pines, Pinus albicaulis and P. balfourianaSparks, Katherine; Hoy-Skubik, Sean L.; Alongi, Franklin; Runyon, Justin B.; Banner, Katharine M.; Smithers, Brian V.; Ulrich, Danielle E. M.
doi: 10.1007/s44391-025-00040-wpmid: N/A
Whitebark pine (Pinus albicaulis, PIAL) and foxtail pine (P. balfouriana, PIBA) are slow-growing, high-elevation, five-needled pines. Recently, PIAL has experienced significant mortality while PIBA has experienced minimal decline. PIBA exists in two disjunct southern (PIBAS) and northern (PIBAN) populations. Our study compared juvenile physiological and morphological traits between the two species (PIAL, PIBA) and foxtail populations (PIBAN, PIBAS) to investigate mechanisms underlying responses to environmental stressors in their high-elevation environments. We grew four-year-old PIAL and PIBA trees in a common greenhouse environment. We measured traits describing their morphology, biomass, stomatal and xylem conduit size and density, budburst phenology, gas exchange, whole plant volatile organic compounds (VOCs), phloem volatile resin (PVR) compounds, and non-structural carbohydrates (NSC). We found that PIAL and PIBA displayed different suites of traits that similarly promote resistance to environmental stressors (e.g., high wind, drought, herbivores). The two PIBA populations did not differ in most traits except for VOCs where PIBAS emitted higher concentrations of specific and total whole plant VOCs than PIBAN, suggesting that PIBAS may differ in susceptibility to stress from PIBAN. For many traits and especially evident in whole plant VOC concentration and composition, PIAL and PIBAN were most similar while PIAL and PIBAS differed the most, consistent with growing season total precipitation of the juveniles’ climates of origin. Our observed trait differences between species and populations offer insight into mechanisms by which PIAL and PIBA juveniles survive in their environments, improving our ability to understand drivers of current and future species distributions.
Foliar Nutrition of Western Hemlock with Stem SinuosityJang, Woongsoon
doi: 10.1007/s44391-025-00042-8pmid: N/A
Stem sinuosity, a growth deformity, reduces timber value, thereby reducing the benefits of fertilization. This study examined the relationship between nutrient deficiency and stem sinuosity for fertilized western hemlock (Tsuga heterophylla (Raf.) Sarg.) on northern Vancouver Island. The site was fertilized at planting (1988; 10 g N, 2.5 g P, and 5 g K per seedling), in 1993 (255 N kg ha−1 + 75 P kg ha−1), and 2004 (255 N kg ha−1), respectively. Foliar samples were analyzed from three groups: 1) fertilized sinuous, 2) fertilized non-sinuous, and 3) unfertilized control (non-sinuous). Fertilized western hemlock had lower nitrogen, potassium (K), and zinc (Zn) concentration levels than the unfertilized control. However, there was no distinct difference in nutrient concentrations between sinuous vs. non-sinuous trees. On the other hand, although individual nutrient trends were insignificant and inconsistent, classification tree analysis may show the potential involvement of multiple nutrients for trees exhibiting sinuosity: sinuous western hemlock trees tended to contain lower levels of K and sulfate simultaneously than the other groups. Therefore, these findings suggested that further research into the potential roles of K, Zn, and sulfate in influencing stem sinuosity in western hemlock, particularly in the context of fertilization, is warranted.Study ImplicationsThe findings highlight that fertilization may inadvertently contribute to western hemlock stem sinuosity, despite beneficial growth, under specific nutrient imbalances. The observed association between lower potassium (K), zinc (Zn), and sulfate levels and stem sinuosity suggests a need for further research into the underlying mechanisms. In particular, future studies should examine the interactions between nutrient dynamics and other environmental factors affecting to stem form variation in western hemlock.