Recent Trends in Large Hardwoods in the Pacific Northwest, USA

Forest densification, wildfires, and disease can reduce the growth and survival of hardwood trees that are important for biological and cultural diversity within the Pacific Northwest of USA. Large, full-crowned hardwoods that produce fruit and that form large cavities used by wildlife were sustained by frequent, low-severity fires prior to Euro-American colonization. Shifts in fire regimes and other threats could be causing declines in, large hardwood trees. To better understand whether and where such declines might be occurring, we evaluated recent trends in Forest Inventory and Analysis (FIA) data from 1991–2016 in California and southern Oregon. We included plots that lay within areas of frequent fire regimes during pre-colonial times and potential forest habitats for fisher, a rare mammal that depends on large live hardwoods. We analyzed changes in basal area for eight hardwood species, both overall and within size classes, over three time periods within ecoregions, and in public and private land ownerships. We found the basal area to generally be stable or increasing for these species. However, data for California black oak suggested a slight decline in basal area overall, and among both very large trees and understory trees; that decline was associated with fire mortality on national forest lands. In addition, mature trees with full crowns appeared to sharply decline across all species. Many trends were not statistically significant due to high variation, especially since more precise data from remeasured trees were only available for the two most recent time periods. Continued analysis of these indicators using remeasured trees will help to evaluate whether conservation efforts are sustaining large, full-crowned trees and their associated benefits.

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Twelve-year responses of planted and naturally regenerating conifers to variable-retention harvest in the Pacific Northwest, USA

Canadian Journal of Forest Research ◽

10.1139/cjfr-2012-0323 ◽

2013 ◽

Vol 43 (1) ◽

pp. 46-55 ◽

Cited By ~ 16

Author(s):

Lauren S. Urgenson ◽

Charles B. Halpern ◽

Paul D. Anderson

Keyword(s):

Pacific Northwest ◽

Natural Regeneration ◽

Regional Scale ◽

Basal Area ◽

Pinus Monticola ◽

Variable Retention ◽

The Pacific ◽

Dispersed Retention ◽

Variable Retention Harvest ◽

Scale Experiment

We studied patterns of conifer regeneration over 12 years as part of a regional-scale experiment in variable-retention harvest in the Pacific Northwest, the DEMO Study. We compared survival and height growth of planted conifers and density and seral composition of natural regeneration among treatments with differing retention levels (15% versus 40%) and patterns (dispersed versus aggregated) replicated across a range of latitudes and forest zones. We also assessed plot-scale relationships of natural regeneration with overstory density and basal area, competing vegetation, and slash accumulations. Early (1- to 2-year) survival of planted seedlings was greater in dispersed treatments (Pinus monticola Douglas ex D. Don, Abies spp.) or unaffected by retention level or pattern (Pseudotsuga menziesii (Mirb.) Franco). Later (5- to 12-year) survival did not differ (all species), but growth was distinctly reduced in dispersed treatments and (or) at higher levels of retention. Density of natural regeneration was 1.5–2.5 times greater in dispersed treatments than in the cleared areas of aggregated treatments. Low-level dispersed retention promoted Pseudotsuga, the early-seral dominant, presumably by enhancing seed rain within a relatively high-light environment. Dispersed retention favored late-seral conifers. The ability to manipulate retention pattern and level to influence regeneration density and composition provides managers with flexibility in developing structurally complex and compositionally diverse forests.

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Past and Present Vulnerability of Closed-Canopy Temperate Forests to Altered Fire Regimes: A Comparison of the Pacific Northwest, New Zealand, and Patagonia

BioScience ◽

10.1093/biosci/biu194 ◽

2014 ◽

Vol 65 (2) ◽

pp. 151-163 ◽

Cited By ~ 21

Author(s):

Cathy Whitlock ◽

David B. McWethy ◽

Alan J. Tepley ◽

Thomas T. Veblen ◽

Andrés Holz ◽

...

Keyword(s):

New Zealand ◽

Pacific Northwest ◽

Temperate Forests ◽

Fire Regimes ◽

The Pacific ◽

Closed Canopy

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Toward a better understanding of climate and human impacts on late Holocene fire regimes in the Pacific Northwest, USA

Progress in Physical Geography Earth and Environment ◽

10.1177/0309133318783144 ◽

2018 ◽

Vol 42 (4) ◽

pp. 478-512 ◽

Cited By ~ 3

Author(s):

Megan K Walsh ◽

Haley J Duke ◽

Kevin C Haydon

Keyword(s):

Pacific Northwest ◽

Ponderosa Pine ◽

Late Holocene ◽

Human Impacts ◽

Fire Severity ◽

Fire Regimes ◽

The Past ◽

The Pacific ◽

Clackamas County ◽

Study Sites

In order to fully appreciate the role that fire, both natural and anthropogenic, had in shaping pre-Euro-American settlement landscapes in the Pacific Northwest (PNW), it is necessary to develop a more robust method of evaluating paleofire reconstructions. Here we demonstrate an approach that includes the identification of charcoal morphotypes (i.e. visually distinct charcoal particles), and incorporates both paleoecological and archaeological data sets, to more specifically determine both the nature of past fire regimes (i.e. fuel type and fire severity) and the likely ignition source of those fires. We demonstrate the usefulness of this approach by reconstructing the late Holocene fire and vegetation histories of Lake Oswego (Clackamas County), Oregon, and Fish Lake (Okanogan County), Washington, using macroscopic charcoal and pollen analysis of sediment cores. The histories were compared with climatic records from the PNW as well as archaeological, ethnographic, and historical records from the Lower Columbia River Valley and Southern Columbia Plateau cultural regions. Our results indicate that while centennial-to-millennial-scale climate change had limited influence on the fire regimes at the study sites during the past ∼3800 years, the use of fire by Native Americans for a variety of reasons, particularly after ca. 1200 calendar years before present (AD 750), had a far greater impact. Charcoal morphotype ratios also indicate that fires in the two watersheds were fundamentally different in their severity and impact, and led to major shifts in the forests and woodlands surrounding Lake Oswego, but helped maintain the ponderosa pine-dominated forest at Fish Lake. The elimination of fire from the two study sites during the past 100–300 years is likely the combined result of Euro-American contact and the arrival of disease in the PNW, as well as 20th-century fire suppression and grazing effects on fuel continuity, which has implications for future forest management and restoration efforts in the PNW.

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Changing wildfire, changing forests: the effects of climate change on fire regimes and vegetation in the Pacific Northwest, USA

Fire Ecology ◽

10.1186/s42408-019-0062-8 ◽

2020 ◽

Vol 16 (1) ◽

Cited By ~ 8

Author(s):

Jessica E. Halofsky ◽

David L. Peterson ◽

Brian J. Harvey

Keyword(s):

Pacific Northwest ◽

Fire Regimes ◽

Tree Regeneration ◽

Ecosystem Change ◽

Fire Intensity ◽

Future Research ◽

Fuel Treatments ◽

Warming Climate ◽

Resource Managers ◽

The Pacific

Abstract Background Wildfires in the Pacific Northwest (Washington, Oregon, Idaho, and western Montana, USA) have been immense in recent years, capturing the attention of resource managers, fire scientists, and the general public. This paper synthesizes understanding of the potential effects of changing climate and fire regimes on Pacific Northwest forests, including effects on disturbance and stress interactions, forest structure and composition, and post-fire ecological processes. We frame this information in a risk assessment context, and conclude with management implications and future research needs. Results Large and severe fires in the Pacific Northwest are associated with warm and dry conditions, and such conditions will likely occur with increasing frequency in a warming climate. According to projections based on historical records, current trends, and simulation modeling, protracted warmer and drier conditions will drive lower fuel moisture and longer fire seasons in the future, likely increasing the frequency and extent of fires compared to the twentieth century. Interactions between fire and other disturbances, such as drought and insect outbreaks, are likely to be the primary drivers of ecosystem change in a warming climate. Reburns are also likely to occur more frequently with warming and drought, with potential effects on tree regeneration and species composition. Hotter, drier sites may be particularly at risk for regeneration failures. Conclusion Resource managers will likely be unable to affect the total area burned by fire, as this trend is driven strongly by climate. However, fuel treatments, when implemented in a spatially strategic manner, can help to decrease fire intensity and severity and improve forest resilience to fire, insects, and drought. Where fuel treatments are less effective (wetter, high-elevation, and coastal forests), managers may consider implementing fuel breaks around high-value resources. When and where post-fire planting is an option, planting different genetic stock than has been used in the past may increase seedling survival. Planting seedlings on cooler, wetter microsites may also help to increase survival. In the driest topographic locations, managers may need to consider where they will try to forestall change and where they will allow conversions to vegetation other than what is currently dominant.

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The Pacific Northwest

10.1093/oxfordhb/9780199858897.013.13 ◽

2016 ◽

Author(s):

Andrew Fisher

Keyword(s):

Native American ◽

Pacific Northwest ◽

Native American History ◽

Native Communities ◽

Columbia Plateau ◽

Cultural Legitimacy ◽

The Pacific ◽

The Us ◽

Political Boundaries ◽

Recent Trends

Despite decades of neglect by professional historians, the Pacific Northwest brings particular clarity to major themes in Native American history. On both sides of the Cascade Mountains and the US-Canadian border, Native communities have carried on the struggle for territorial integrity, political authority, economic viability, and cultural legitimacy that began in the late eighteenth century. Scholars, in turn, have broadened their studies temporally, culturally, and thematically to create a fuller picture of the region’s past. This chapter surveys recent trends in the ethnohistorical literature concerning the diverse indigenous peoples of the Northwest Coast and Columbia Plateau. For the sake of brevity, it emphasizes three themes of particular salience in the Northwest: the porous character of cultural and political boundaries, the fluidity of racial and tribal identities, and the determination of Native nations to protect their ancestral lands and resources.

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Tools for Assessing Climate Impacts on Fish and Wildlife

Journal of Fish and Wildlife Management ◽

10.3996/062012-jfwm-055 ◽

2013 ◽

Vol 4 (1) ◽

pp. 220-241 ◽

Cited By ~ 8

Author(s):

Chad B. Wilsey ◽

Joshua J. Lawler ◽

Edwin P. Maurer ◽

Donald McKenzie ◽

Patricia A. Townsend ◽

...

Keyword(s):

Climate Change ◽

Pacific Northwest ◽

Puget Sound ◽

Fire Regimes ◽

Climate Impacts ◽

Wildlife Habitat ◽

Individual Species ◽

Willamette Valley ◽

The Pacific ◽

Georgia Basin

Abstract Climate change is already affecting many fish and wildlife populations. Managing these populations requires an understanding of the nature, magnitude, and distribution of current and future climate impacts. Scientists and managers have at their disposal a wide array of models for projecting climate impacts that can be used to build such an understanding. Here, we provide a broad overview of the types of models available for forecasting the effects of climate change on key processes that affect fish and wildlife habitat (hydrology, fire, and vegetation), as well as on individual species distributions and populations. We present a framework for how climate-impacts modeling can be used to address management concerns, providing examples of model-based assessments of climate impacts on salmon populations in the Pacific Northwest, fire regimes in the boreal region of Canada, prairies and savannas in the Willamette Valley-Puget Sound Trough-Georgia Basin ecoregion, and marten Martes americana populations in the northeastern United States and southeastern Canada. We also highlight some key limitations of these models and discuss how such limitations should be managed. We conclude with a general discussion of how these models can be integrated into fish and wildlife management.

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Estimating the Avoided Fuel-Treatment Costs of Wildfire

Western Journal of Applied Forestry ◽

10.1093/wjaf/23.4.197 ◽

2008 ◽

Vol 23 (4) ◽

pp. 197-201 ◽

Cited By ~ 4

Author(s):

Geoffrey H. Donovan ◽

Thomas C. Brown

Keyword(s):

Pacific Northwest ◽

Pinus Ponderosa ◽

Ponderosa Pine ◽

Stand Structure ◽

National Forest ◽

Wildfire Management ◽

Fuel Treatment ◽

Beneficial Effects ◽

The Pacific ◽

Large Trees

Abstract Although the importance of wildfire to fire-adapted ecosystems is widely recognized, wildfire management has historically placed less emphasis on the beneficial effects of wildfire. We estimate the avoided fuel treatment cost for 10 ponderosa pine (Pinus ponderosa) stands on the Umatilla National Forest in the Pacific Northwest. Results show that fires in stands that show the greatest divergence from the archetypical ponderosa pine stand structure (large trees in an open, parklike stand) tend to have higher avoided costs. This is a reflection of the higher cost of fuel treatments in these stands: treatments designed to restore a stand to a desired condition are normally more expensive than treatments to maintain a stand in a desired condition.

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Did early logging or changes in disturbance regimes promote high tree densities in river red gum forests?

Australian Journal of Botany ◽

10.1071/bt16025 ◽

2016 ◽

Vol 64 (6) ◽

pp. 530 ◽

Cited By ~ 7

Author(s):

Hugh W. McGregor ◽

Matthew J. Colloff ◽

Ian D. Lunt

Keyword(s):

Stand Structure ◽

Root Zone ◽

Canopy Cover ◽

Basal Area ◽

Stem Density ◽

Mature Trees ◽

Large Trees ◽

Zone Of Influence ◽

Disturbance Recovery ◽

River Red Gum

Density of woody plants is thought to have increased in many ecosystems in Australia since European colonisation. Globally, there has been much debate as to whether this phenomenon is driven by the process of post-disturbance recovery – whereby historical logging resulted in the replacement of large, mature trees with smaller, younger trees – or by the process of encroachment – whereby cessation of disturbance events reduced the mortality of seedlings and saplings. We examined the extent to which historical changes in forest structure are compatible with each of these models. The study was conducted in river red gum Eucalyptus camaldulensis Dehnh. floodplain forest on the River Murray at Millewa Forest, southern New South Wales. We compared ‘historical’ (~1860s) stand structure to ‘current’ structure in 45 one-hectare quadrants randomly stratified between three forest productivity classes. Historical trees were determined by stumps or stags likely to have been cut during the late 1800s. Size and position of each historical and current tree was recorded, and used to calculate stem density, basal area, canopy cover and the area of the ‘zone of influence’ (the peripheral extent of the root zone). Current stand structure was vastly different from historical structure. Stem density has increased 9-fold, from a mean of 17 (historical) to 147 (current) trees ha–1. However, basal area increased only slightly, from 13.0 to 15.3 m2 ha–1. Canopy cover increased substantially from 22.1 to 33.5% cover, as did zone of influence, from 55 to 81% cover. Evidence for both the post-disturbance recovery and encroachment hypotheses was found. The 9-fold increase in stem density between historical and current stands was attributable largely to the replacement of large trees with small trees, because basal area had increased only slightly (by 18%). However, the increase in basal area was associated with a substantial increase in canopy cover and area of the zone of influence, supporting the encroachment hypothesis. Regardless, the post-disturbance recovery hypothesis accounts for the bulk of changes in this river red gum forest.

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