Principles and practices for the restoration of ponderosa pine and dry mixed-conifer forests of the Colorado Front Range

Fire suppression has increased stand density and risk of severe, stand‐replacing wildfire in lower elevation dry conifer forests of western North America, threatening ecological function. The U.S. Forest Service’s Collaborative Forest Landscape Restoration Program (CFLRP) aims to mitigate impacts to ecological function, while mandating effectiveness monitoring to verify restoration success. Expected benefits include improved conditions for biodiversity, but relatively few empirical studies evaluate restoration effects on biodiversity. We applied the Integrated Monitoring in Bird Conservation Regions program to survey birds in relation to CFLRP treatments along the Colorado Front Range in 2015–2017. We employed hierarchical models to analyze species occupancy and richness at 1972 points nested within 141 1‐km2 grid cells. Our objectives were to investigate (1) species occupancy relationships with treatments at local (point) and landscape (grid) spatial scales, (2) potential mechanisms for treatment relationships considering species and treatment relationships with forest structure and composition (i.e., habitat relationships), and (3) treatment and habitat relationships with species richness. The data supported positive and negative point‐level treatment relationships, suggesting uneven species distributions between treated and untreated points. At the grid scale, however, we only found positive species relationships with percent area treated, and accordingly, grid‐level species richness increased with treatment extent. Potential mechanisms for treatment relationships included treatments generating foraging opportunities for aerial insectivores by opening the canopy, improving conditions for ground‐associated species by increasing herbaceous growth, and limiting opportunities for shrub‐nesting species by reducing shrub cover. Landscape‐scale patterns suggest CFLRP treatments can benefit avian communities by generating habitat for open‐forest species without necessarily eliminating habitat for closed‐forest species. Our results provide evidence for a commonly expected but rarely verified pattern of increased species richness with forest heterogeneity. We suggest restoration treatments will most benefit forest bird diversity by reducing canopy cover, encouraging herbaceous ground cover, limiting ladder fuel species, and encouraging shrub diversity in canopy openings, while maintaining some dense forest stands on the landscape.

Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 78%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Dry conifer forest restoration benefits Colorado Front Range avian communities

Latif¹,

Truex

Sparks³

et al. 2020

Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests

Hagmann

Hessburg

Prichard

et al. 2021

191

140

Implementation of wildfire-and climate-adaptation strategies in seasonally dry forests of western North America is impeded by numerous constraints and uncertainties. After more than a century of resource and land use change, some question the need for proactive management, particularly given novel social, ecological, and climatic conditions. To address this question, we first provide a framework for assessing changes in landscape conditions and fire regimes. Using this framework, we then evaluate evidence of change and lack of change in contemporary conditions relative to those maintained by active fire regimes, i.e., those uninterrupted by a century or more of human-induced fire exclusion. The cumulative results of more than a century of research document a persistent and substantial fire deficit and widespread alterations to ecological structures and functions. These changes are not necessarily apparent at all spatial scales or in all dimensions of fire regimes and forest and nonforest conditions. Nonetheless, loss of the once abundant influence of low-and moderate-KEYWORDS

Low‐ and moderate‐severity fire offers key insights for landscape restoration in ponderosa pine forests

Cannon

Warnick

Elliott

et al. 2021

Self Cite

Restoration goals in fire‐prone conifer forests include mitigating fire hazard while restoring forest structural components linked to disturbance resilience and ecological function. Restoration of overstory spatial pattern in forests often falls short of management objectives due to complexities in implementation, regulation, and available data. When historical data is available, it is often collected at plots too small to inform coarse‐scale metrics like gap size and structure of tree patches (e.g., 1 ha). Principles of ecological forestry typically emphasize overstory removal patterns that emulate those of natural disturbances. So, low‐ and moderate‐severity portions of contemporary wildfires may serve as a guide to restoration treatments where mixed‐severity fires occur. Here, we compare forest spatial pattern and configuration in 15 mechanical restoration treatments and low‐ and moderate‐severity portions of three wildfires in ponderosa pine‐dominated forests to determine how they differ in spatial pattern. We obtained satellite imagery of restoration treatments and wildfires and used supervised classification to differentiate canopy and openings. We assessed elements of landscape structure including canopy and gap cover, gap attributes, and landscape heterogeneity for each disturbance type. We found that both mechanical restoration treatments and low‐ and moderate‐severity portions of wildfires reduced forest cover, increased gap cover, and altered pattern and arrangement of gaps relative to undisturbed areas, though the magnitude of changes were greatest in the burned sites. Low‐ and moderate‐severity wildfire consistently increased landscape heterogeneity, but mechanical treatments did not. This suggests that a greater emphasis on increasing gap and patch spatial structure may make mechanical treatments more congruent with natural disturbances. Outcomes of low‐ and moderate‐severity portions of wildfires may provide important information upon which to base management prescriptions where reference data on landscape patterns is unavailable.