Douglas-fir encroachment reduces drought resistance in Oregon white oak of northern California

Due to a suite of environmental changes, Oregon white oak (Quercus garryana Douglas ex Hook; called Gary oak in Canada) associated ecosystems at many North American sites are being encroached upon by Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) and other conifer species. Alteration of stand structure and composition is causing substantial changes in the dynamics of these ecosystems, creating an environment in which Oregon white oak is not thriving. In this study we used dendrochronology to investigate the competitive dynamics between Oregon white oak and Douglas-fir in a mixed forest stand on Southern Vancouver Island. Significant species-specific differences in radial growth sensitivity to drought were found between Oregon white oak and Douglas-fir. Oregon white oak trees growing at high densities, or competing with Douglas-fir for moisture were found to be more sensitive to drought and more sensitive to growing conditions during the prior year. The response of Douglas-fir to drought was less variable, possibly due to the relatively low conifer densities at our study site, as well as the species’ ability to root graft, its higher shade tolerance than Oregon white oak, and its rapid growth rates that allow it to achieve a more dominant canopy position. The non-stationary response to climate exhibited by Oregon white oak provides insights into the mechanisms by which Oregon white oak savannas are being converted to coniferous woodland, but also suggest that tree-ring reconstructions of climate need to explicitly address changes in stand dynamics that could influence the growth–climate relationship

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Fire History of a Douglas-Fir-Oregon White Oak Woodland, Waldron Island, Washington

Northwest Science ◽

10.3955/046.085.0203 ◽

2011 ◽

Vol 85 (2) ◽

pp. 108-119 ◽

Cited By ~ 14

Author(s):

Carson B. Sprenger ◽

Peter W. Dunwiddie

Keyword(s):

Fire History ◽

Douglas Fir ◽

Oak Woodland ◽

White Oak ◽

History Of ◽

Oregon White Oak

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Synchronicity and Geographic Variation in Oregon White Oak Acorn Production in the Pacific Northwest

Northwest Science ◽

10.3955/046.083.0203 ◽

2009 ◽

Vol 83 (2) ◽

pp. 117-130 ◽

Cited By ~ 10

Author(s):

David H. Peter ◽

Constance A. Harrington

Keyword(s):

Geographic Variation ◽

Pacific Northwest ◽

White Oak ◽

Acorn Production ◽

The Pacific ◽

Oregon White Oak

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Between- and Within-Tree Variation in the Anatomy and Specific Gravity of Wood in Oregon White Oak (Quercus Garryana Dougl.)

IAWA Journal ◽

10.1163/22941932-90000642 ◽

1996 ◽

Vol 17 (4) ◽

pp. 445-461 ◽

Cited By ~ 37

Author(s):

Hua Lei ◽

Michael R. Milota ◽

Barbara L. Gartner

Keyword(s):

Specific Gravity ◽

Pseudotsuga Menziesii ◽

Fibre Length ◽

Wood Properties ◽

Vessel Diameter ◽

Coast Range ◽

Quercus Garryana ◽

White Oak ◽

Earlywood Vessel ◽

Oregon White Oak

In order to analyze the variation in wood properties within and between trees of an underutilized tree species, we sampled six Oregon white oak (Quercus garryana Dougl.) trees from an 80-year old mixed stand of Q. garryana and Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) in the Coast Range of Western Oregon, USA. Fibre length, earlywood vessel diameter, tissue proportions, and specific gravity were measured on samples across the diameter at two heights. Trees had a slight lean (2-12°), so we sampled separately both radii of a diametric strip that ran from the lower to upper side of lean.

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Resilience of Oregon white oak to reintroduction of fire

Fire Ecology ◽

10.1186/s42408-019-0045-9 ◽

2019 ◽

Vol 15 (1) ◽

Author(s):

Deborah G. Nemens ◽

J. Morgan Varner ◽

Peter W. Dunwiddie

Keyword(s):

White Oak ◽

Oregon White Oak

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Effectiveness and impacts of girdling treatments in a conifer-encroached Oregon white oak woodland

Forest Ecology and Management ◽

10.1016/j.foreco.2019.05.059 ◽

2019 ◽

Vol 447 ◽

pp. 77-86

Author(s):

Jeffrey M. Kane ◽

Eamon A. Engber ◽

John E. McClelland

Keyword(s):

Oak Woodland ◽

White Oak ◽

Oregon White Oak

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Suppressed crown expansion and increased bud density after precommercial thinning in California Douglas-fir

Canadian Journal of Forest Research ◽

10.1139/x83-163 ◽

1983 ◽

Vol 13 (6) ◽

pp. 1246-1248 ◽

Cited By ~ 3

Author(s):

Douglas A. Maguire

Keyword(s):

Douglas Fir ◽

Northern California ◽

Precommercial Thinning

A densely regenerated Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) plantation in northern California was precommercially thinned from approximately 15 000 stems/ha to 740 stems/ha. Trees in an unthinned strip served as control for analyzing thinning responses. The terminal and lateral leader growth of "released" trees were significantly reduced after thinning, but the number of buds was significantly increased.

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Changes in drought resistance and root growth capacity of container seedlings in response to nursery drought, nitrogen, and potassium treatments

Canadian Journal of Forest Research ◽

10.1139/x92-100 ◽

1992 ◽

Vol 22 (5) ◽

pp. 740-749 ◽

Cited By ~ 42

Author(s):

R. van den Driessche

Keyword(s):

Drought Stress ◽

Root Growth ◽

Drought Resistance ◽

Lodgepole Pine ◽

Dry Weight ◽

White Spruce ◽

Douglas Fir ◽

Growth Capacity ◽

Root Growth Capacity ◽

N Treatment

Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), lodgepole pine (Pinuscontorta Dougl.), and white spruce (Piceaglauca (Moench) Voss) seedlings, each represented by two seed lots, were grown in Styroblock containers in a greenhouse and plastic shelter house from February 1989 to January 1990. The seedlings were exposed to two nitrogen (N) treatments and three potassium (K) treatments arranged factorially within three drought treatments. After winter storage, seedlings from a complete set of treatments were planted into hygric, mesic, and xeric sand beds during 12–14 March. Increasing nursery drought stress increased survival of Douglas-fir and lodgepole pine after planting, and high N treatment level increased survival of lodgepole pine and white spruce. Under xeric conditions, combined nursery drought and high N treatments increased survival of lodgepole pine by 33%, indicating the importance of nursery cultural regime for stock quality. Increase in nursery drought decreased seedling size relatively little, but increase in N increased seedling size one season after planting. A positive relationship between shoot/root ratio and survival in lodgepole pine and white spruce indicated that increase in N increased both shoot growth and drought resistance over the N range investigated. Only Douglas-fir showed an interaction between drought and N treatment and a small response in both survival and dry weight to K. Root growth capacity, measured at the time of planting, showed an approximate doubling in all species due to high N treatment, and was also increased in white spruce by drought stress. Survival and root growth capacity were poorly correlated, but dry-weight growth in sand beds was well correlated with root growth capacity. Shoot dry weight and percent N in shoots measured after nursery growth were correlated with root growth capacity. Manipulation of root growth capacity by changing nursery treatment was apparently possible without altering resistance to drought stress after planting.

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