Spatial patterns of ponderosa pine regeneration in high-severity burn patches

We examine regeneration dynamics across landscapes under extreme climate conditions and a human-altered fire regime in ponderosa pine (Pinus ponderosa Douglas ex Lawson & C. Lawson) forests of the American Southwest. Our research asks how well these forests recover when unprecedented conditions of a high-severity fire regime combine with historical drought conditions. Tree recruitment is documented at five sites in New Mexico after high-severity fires that burned forests in the drought that prevailed from ∼1945 to 1958. We develop a water-balance type model to evaluate how altered microclimate conditions in the years after a fire and during a drought may inhibit ponderosa pine regeneration in comparison with drought conditions alone. We empirically identify two pathways of forest recovery following high-severity fires during drought: recovery to nonforest types, either dense shrubfields or shrubs in grasslands (four sites) or recovery to hyperdense forest (one site). Model simulations predict fewer favorable opportunities for germination, fewer periods favorable for seedling establishment, shortening of favorable establishment periods, and more adverse conditions because of later spring and earlier fall hard freezes. Our research suggests that a specific climate window critical to the capacity of southwestern ponderosa pine trees to regenerate is narrowed by a synchronous occurrence of high-severity fire and drought.

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Moisture and vegetation cover limit ponderosa pine regeneration in high-severity burn patches in the southwestern US

Fire Ecology ◽

10.1186/s42408-021-00095-3 ◽

2021 ◽

Vol 17 (1) ◽

Author(s):

Megan P. Singleton ◽

Andrea E. Thode ◽

Andrew J. Sánchez Meador ◽

Jose M. Iniguez

Keyword(s):

Ponderosa Pine ◽

Seedling Establishment ◽

Canopy Cover ◽

Seedling Density ◽

Ponderosa Pine Forests ◽

High Severity ◽

Pine Regeneration ◽

Core Areas ◽

Gambel Oak ◽

Patch Edge

Abstract Background Fire regimes are shifting in ponderosa pine (Pinus ponderosa Lawson & C. Lawson)-dominated forests, raising concern regarding future vegetation patterns and forest resilience, particularly within high-severity burn patches. The southwestern US has recently experienced a marked increase in large fires that produce large, high-severity patch interiors, with few surviving trees. These areas could be more susceptible for forest loss and conversions to alternative vegetation types than areas closer to the forest edge with more available seed sources. To better understand forest recovery, we surveyed ponderosa pine regeneration within edge and core areas (>200 m from edge) of high-severity patches in ten fires that burned between 1996 to 2008 across Arizona and New Mexico, USA. Specifically, we compared regeneration density, height, and canopy cover in patch edge and core areas and used generalized linear models to investigate the abiotic and biotic factors that contribute to ponderosa pine seedling establishment and density. Results High-severity burn-patch edge and core plots were not significantly different in seedling density, height, or canopy cover across fires. Seedling establishment was more likely at higher-elevation mesic sites and less likely when Gambel oak (Quercus gambelii Nutt.) was more abundant. Seedling density was negatively impacted by shrub, grass, and Gambel oak cover. Conclusions Regeneration density varied among fires but analysis of regeneration in aggregated edge and core plots showed that abundance of seed availability was not the sole factor that limited ponderosa pine regeneration, probably because of surviving tree refugia within high-severity burn patches. Furthermore, our findings emphasize that ponderosa pine regeneration in our study area was significantly impacted by xeric topographic environments and vegetation competition. Continued warm and dry conditions and increased wildfire activity may delay the natural recovery of ponderosa pine forests, underscoring the importance of restoration efforts in large, high-severity burn patches.

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Modeling high-severity fire, drought and climate change impacts on ponderosa pine regeneration

Ecological Modelling ◽

10.1016/j.ecolmodel.2012.12.029 ◽

2013 ◽

Vol 253 ◽

pp. 56-69 ◽

Cited By ~ 36

Author(s):

Johannes J. Feddema ◽

Joy Nystrom Mast ◽

Melissa Savage

Keyword(s):

Climate Change ◽

Ponderosa Pine ◽

Climate Change Impacts ◽

High Severity ◽

Pine Regeneration

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Limits to Ponderosa Pine Regeneration following Large High-Severity Forest Fires in the United States Southwest

Fire Ecology ◽

10.4996/fireecology.140114316 ◽

2018 ◽

Vol 14 (1) ◽

pp. 143-163 ◽

Cited By ~ 19

Author(s):

Collin Haffey ◽

Thomas D. Sisk ◽

Craig D. Allen ◽

Andrea E. Thode ◽

Ellis Q. Margolis

Keyword(s):

United States ◽

Forest Fires ◽

Ponderosa Pine ◽

The United States ◽

High Severity ◽

Pine Regeneration ◽

United States Southwest

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Ponderosa Pine Regeneration, Wildland Fuels Management, and Habitat Conservation: Identifying Trade-Offs Following Wildfire

Forests ◽

10.3390/f10030286 ◽

2019 ◽

Vol 10 (3) ◽

pp. 286 ◽

Cited By ~ 1

Author(s):

Victoria Donovan ◽

Caleb Roberts ◽

Carissa Wonkka ◽

David Wedin ◽

Dirac Twidwell

Keyword(s):

Species Richness ◽

Ponderosa Pine ◽

Fire Management ◽

Woody Debris ◽

Pine Forest ◽

Habitat Conservation ◽

Fuels Management ◽

Management Objectives ◽

Pine Regeneration ◽

Ponderosa Pine Forest

Increasing wildfires in western North American conifer forests have led to debates surrounding the application of post-fire management practices. There is a lack of consensus on whether (and to what extent) post-fire management assists or hinders managers in achieving goals, particularly in under-studied regions like eastern ponderosa pine forests. This makes it difficult for forest managers to balance among competing interests. We contrast structural and community characteristics across unburned ponderosa pine forest, severely burned ponderosa pine forest, and severely burned ponderosa pine forest treated with post-fire management with respect to three management objectives: ponderosa pine regeneration, wildland fuels control, and habitat conservation. Ponderosa pine saplings were more abundant in treated burned sites than untreated burned sites, suggesting increases in tree regeneration following tree planting; however, natural regeneration was evident in both unburned and untreated burned sites. Wildland fuels management greatly reduced snags and coarse woody debris in treated burned sites. Understory cover measurements revealed bare ground and fine woody debris were more strongly associated with untreated burned sites, and greater levels of forbs and grass were more strongly associated with treated burned sites. Wildlife habitat was greatly reduced following post-fire treatments. There were no tree cavities in treated burned sites, whereas untreated burned sites had an average of 27 ± 7.68 cavities per hectare. Correspondingly, we found almost double the avian species richness in untreated burned sites compared to treated burned sites (22 species versus 12 species). Unburned forests and untreated burned areas had the same species richness, but hosted unique avian communities. Our results indicate conflicting outcomes with respect to management objectives, most evident in the clear costs to habitat conservation following post-fire management application.

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Tree and opening spatial patterns vary by tree density in two old-growth remnant ponderosa pine forests in Northern Arizona, USA

Forest Ecology and Management ◽

10.1016/j.foreco.2019.117502 ◽

2019 ◽

Vol 450 ◽

pp. 117502 ◽

Cited By ~ 1

Author(s):

Jose M. Iniguez ◽

James F. Fowler ◽

W. Keith Moser ◽

Carolyn H. Sieg ◽

L. Scott Baggett ◽

...

Keyword(s):

Spatial Patterns ◽

Ponderosa Pine ◽

Tree Density ◽

Pine Forests ◽

Old Growth ◽

Ponderosa Pine Forests ◽

Northern Arizona

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What drives ponderosa pine regeneration following wildfire in the western United States?

Forest Ecology and Management ◽

10.1016/j.foreco.2019.117663 ◽

2019 ◽

Vol 454 ◽

pp. 117663 ◽

Cited By ~ 12

Author(s):

Julie E. Korb ◽

Paula J. Fornwalt ◽

Camille S. Stevens-Rumann

Keyword(s):

United States ◽

Ponderosa Pine ◽

Western United States ◽

Pine Regeneration

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Variability in Mixed Conifer Spatial Structure Changes Understory Light Environments

Forests ◽

10.3390/f10111015 ◽

2019 ◽

Vol 10 (11) ◽

pp. 1015 ◽

Cited By ~ 2

Author(s):

Jeffery B. Cannon ◽

Wade T. Tinkham ◽

Ryan K. DeAngelis ◽

Edward M. Hill ◽

Mike A. Battaglia

Keyword(s):

Spatial Patterns ◽

Ponderosa Pine ◽

Spatial Scales ◽

Light Availability ◽

Structural Complexity ◽

Tree Regeneration ◽

Conifer Forests ◽

Mixed Conifer ◽

Regeneration Dynamics ◽

Wide Range

In fire-adapted conifer forests of the Western U.S., changing land use has led to increased forest densities and fuel conditions partly responsible for increasing the extent of high-severity wildfires in the region. In response, land managers often use mechanical thinning treatments to reduce fuels and increase overstory structural complexity, which can help improve stand resilience and restore complex spatial patterns that once characterized these stands. The outcomes of these treatments can vary greatly, resulting in a large gradient in aggregation of residual overstory trees. However, there is limited information on how a range of spatial outcomes from restoration treatments can influence structural complexity and tree regeneration dynamics in mixed conifer stands. In this study, we model understory light levels across a range of forest density in a stem-mapped dry mixed conifer forest and apply this model to simulated stem maps that are similar in residual basal area yet vary in degree of spatial complexity. We found that light availability was best modeled by residual stand density index and that consideration of forest structure at multiple spatial scales is important for predicting light availability. Second, we found that restoration treatments differing in spatial pattern may differ markedly in their achievement of objectives such as density reduction, maintenance of horizontal and tree size complexity, and creation of microsite conditions favorable to shade-intolerant species, with several notable tradeoffs. These conditions in turn have cascading effects on regeneration dynamics, treatment longevity, fire behavior, and resilience to disturbances. In our study, treatments with high aggregation of residual trees best balanced multiple objectives typically used in ponderosa pine and dry mixed conifer forests. Simulation studies that consider a wide range of possible spatial patterns can complement field studies and provide predictions of the impacts of mechanical treatments on a large range of potential ecological effects.

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The Effect of Cattle Grazing on Ponderosa Pine Regeneration

The Forestry Chronicle ◽

10.5558/tfc67245-3 ◽

1991 ◽

Vol 67 (3) ◽

pp. 245-248 ◽

Cited By ~ 1

Author(s):

J. L. Kingery ◽

R. T. Graham

Keyword(s):

Pinus Ponderosa ◽

Ponderosa Pine ◽

Habitat Type ◽

Total Mortality ◽

Cattle Grazing ◽

Nez Perce ◽

Tree Seedlings ◽

Tree Seedling ◽

Pine Regeneration ◽

Study Sites

During the summer and fall of 1982, a study was established on the Nez Percé National Forest in central Idaho to assess the effects of cattle grazing on the performance of a new ponderosa pine (Pinus ponderosa Laws.) plantation. Three study sites were located in a Douglas-fir/ninebark (Pseudotsuga menziesii/Physocarpus malvaceus) habitat type. Results after six years showed that livestock use can influence tree seedling establishment. Mortality and damage to tree seedlings from cattle resulted primarily from trampling rather than from browsing. Five and one-half percent of the seedlings were damaged by cattle, of which 3.6% died. Browsing by deer and elk caused the most growth loss. Overall damage was greatest from non-animal causes. Seedling quality at the time of planting, handling of the seedling, and droughty conditions during the first two years of the study contributed to this type of damage. Overall performance of the tree seedlings were relatively poor. Total mortality to tree seedlings resulting from all sources of damage was 43.6% for the grazed treatment and 25.3% for the non-grazed treatment.

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Post-fire seeding with ryegrass: implications for understorey plant communities and overall effectiveness

International Journal of Wildland Fire ◽

10.1071/wf13013 ◽

2015 ◽

Vol 24 (4) ◽

pp. 518

Author(s):

Melissa A. McMaster ◽

Andrea Thode ◽

Michael Kearsley

Keyword(s):

Ponderosa Pine ◽

Plant Cover ◽

Ground Cover ◽

Plant Invasions ◽

Bare Soil ◽

Italian Ryegrass ◽

Exotic Plant ◽

Vegetative Cover ◽

High Severity ◽

Significant Difference

Seeding following high-severity wildfires is motivated by the goals of increasing vegetative cover and decreasing bare soil in order to minimise soil erosion and exotic plant invasions. We compared the ground cover and vegetation response of seeded versus non-seeded areas located in the Warm Fire in northern Arizona, where post-fire seeding treatments with Italian ryegrass (Lolium perenne spp. multiflorum (L.)) were conducted in 4000 ha of high-severity burned areas. Over the course of the study, we observed no significant difference between seeded and non-seeded plots in percentage of bare soil, total vegetative cover or exotic plant cover. However, there were significant differences in plant community composition as revealed by PERMANOVA and Indicator Species Analysis. Two years post-fire there were significantly fewer ponderosa pine seedlings, and the cover of annual and biennial forbs was significantly lower in plots that were seeded with Italian ryegrass. In the third year, the cover of native bunch grasses was significantly lower in seeded plots. The differences we observed may be due to differences in pre-existing vegetation composition because of the geographic separation of the plots across the landscape. Our results illustrate the ineffectiveness of post-fire seeding in achieving the goals of increasing vegetative cover and decreasing the invasion of non-native plants, and we suggest that alternative post-fire remediation should be considered in the future.

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