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Ponderosa pine seedling height growth beneath partial overstories in the central Oregon C

Ponderosa pine seedling height growth beneath partial overstories in the central Oregon Cascade Range. Woongsoon Jang 1 Christopher R. Keyes 1 , David L.R. Affleck 1 , and Douglas A. Maguire 2.

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Ponderosa pine seedling height growth beneath partial overstories in the central Oregon C

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  1. Ponderosa pine seedling height growth beneath partial overstories in the central Oregon Cascade Range Woongsoon Jang1 Christopher R. Keyes1, David L.R. Affleck1, and Douglas A. Maguire2 1Department of Forest Management, College of Forestry and Conservation, University of Montana 2Department of Forest Engineering, Resources & Management, Oregon State University

  2. Partial overstory retention • Compromise between timber production and ecological objectives • Enhance structural complexity • Increase species diversity • Facilitating ponderosa pine seedling recruitment and survival • Enhance seed availability • Ameliorate environmental stressors • For silviculturists • Effect on growth rates of seedling?

  3. Negative effects on seedling growth • Negative relationship between seedling growth and overstory density, distance, etc. • But, number of study is few: • Because seedling growth prior to overstory removal was not concerned • Overstory retention level is constrained and retained temporary

  4. Objectives • Understand overstory/understory relationships of two-aged ponderosa pine stands arising from dispersed variable-retention harvests • How the growth of seedlings and saplings is influenced by varying levels of overstory retention • How the overstory/seedling growth relationship changes in different environments

  5. Study Site

  6. Climate of study site

  7. Site description

  8. Collected data

  9. Data analyses • Generalized linear model (GLM) • Random component (probability distribution) • Gamma distribution • Linear predictor • Link function • Log transformation

  10. Results

  11. Overstory vs. Understory • Negative effect on seedling height growth • 10 cm increase of QMD  0.92% reduction • e-0.0092 = 0.9908 • Additional 10 tree/ha  5.35% reduction • e-0.0550 = 0.9465 • Similar results with other studies and species • Ponderosa pine (Oliver and Dolph,1992; McDonald and Abbott 1994) • Douglas-fir (Isaac 1956; Wampler 1993; Hansen et al. 1995) • Scots pine (Elfving and Jakobsson 2006)

  12. Best measure of overstory? • Basal Area (BA) • Many study have used • E.g. Rose and Muir 1997; Acker et al. 1998; Page et al. 2001 • Not merely a measure of aboveground competition • Correlated with foliage or canopy coverage, root competition, etc. • Combination of tree density and QMD • Account for more variance than BA

  13. How big should the plot size be? • Key question from competition indices • So-called “zone of influence” (Opie 1968) • Optimum radius of overstory plot • Vary with tree size (Wagner and Radosevich 1991) • 3.5 times of the mean crown radius (Lorimer 1983) • Bigger plot explains more variance • Beyond 18.29 m  ignorable (Hoyer 1993) • Min. effective distance 12.19 m (McDonald 1976) • Thus, 15 m radius is the most relevant

  14. Shade? Or others? • What causes the reduction of seedling growth? • Light condition • Influences ponderosa pine seedlings more than any other factor • Decreases with overstory basal area increment (Oliver and Dolph 1992) • Modifies tree attributes (Pearson 1936, Messier et al. 1999) • Others? • Soil moisture (McDonald and Abbot 1994) • Competition for nutrients and low soil temperature (Lajzerowicz et al. 2004)

  15. Prescribed burning • Reduces fuel load, improves seedling recruitment, simulates thinning effect, etc. • However, the effect of prescribed burning has been debated for a long time • Negative effect in this study • Loss of total biomass of duff layer • Subsequent nutrient deficiency • Takes long time to recover to the level of pre-burn • Limitation of total nutrient supply (especially N) • Delayed recovery of N-fixation shrubs (eg. Ceanothusvelutinus, Purshiatridentata)

  16. Planting • Already selected seedlings • Have better geno- & phenotype • Already grown enough to compete • Planter could control the place to be planted

  17. Understory veg. & seedling growth

  18. Management implications • Controlling seedling height growth • Manipulation of overstory retention level • Number and size of overstory retention trees • Introduction of site preparation method or artificial planting • Effects of other factors on seedling behavior • stand history, potential productivity, and understory condition

  19. Management implications

  20. Going further… • Spatial pattern of overstory retention? • Palik et al. 2003; Maguire et al. 2006 • Climate? • How do seedlings respond to the weather during growing season? • Refinement of understory veg. variables • Plot level measurement were not appropriate • Shrub species composition • Interaction (e.g. competition vs. facilitation?) with seedling along with site condition and seedling size, etc.

  21. Cited literature • Acker, S.A., E. Zenner, and W. Emmingham. 1998. Structure and yield of two-aged stands on the Willamette National Forest, Oregon: implications for green tree retention. Canadian Journal of Forest Research 28(5):749-758. • Hansen, A.J., S.L. Garman, J.F. Weigand, D.L. Urban, W.C. McComb, and M.G. Raphael. 1995. Alternative Silvicultural Regimes in the Pacific Northwest: Simulations of Ecological and Economic Effects. Ecological Applications 5(3):535-554. • Hoyer, G.E. 1993. The influence of Douglas-fir overstory on understory tree height growth in coastal forests of Washington. Washington Department Natural Resources Forest Land Management Research Center. Contribution No. 348. • Isaac, L.A. 1956. Place of partial cutting in old-growth stands of the Douglas-fir region. US Dept. of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. Research Paper 16. PNW-RP-16. p 48. • Lajzerowicz, C.C., M.B. Walters, M. Krasowski, and H.B. Massicotte. 2004. Light and temperature differentially colimit subalpine fir and Engelmann spruce seedling growth in partial-cut subalpine forests. Canadian Journal of Forest Research 34(1):249-260. • Lorimer, C.G. 1983. Tests of age-independent competition indices for individual trees in natural hardwood stands. Forest Ecology and Management 6(4):343-360. • Maguire, D., D. Mainwaring, and C. Halpern. 2006. Stand dynamics after variable-retention harvesting in mature Douglas-fir forests of western North America. AllgemeineForst und Jagdzeitung 177(6/7):120. • McDonald, P.M. 1976. Inhibiting Effect of Ponderosa Pine Seed Trees on Seedling Growth. Journal of Forestry 74(4):220-224. • McDonald, P.M., and C.S. Abbott. 1994. Seedfall, regeneration, and seedling development in group-selection openings. U.S. Department of Agriculture, Forest Service Research Paper PSW-RP-220. 13p. • Messier, C., R. Doucet, J.-C. Ruel, Y. Claveau, C. Kelly, and M.J. Lechowicz. 1999. Functional ecology of advance regeneration in relation to light in boreal forests. Canadian Journal of Forest Research 29(6):812-823. • Oliver, W.W., and L.K. Dolph. 1992. Mixed-conifer seedling growth varies in response to overstory release. Forest Ecology and Management 48(1-2):179-183. • Opie, J.E. 1968. Predictability of Individual Tree Growth Using Various Definitions of Competing Basal Area. Forest Science 14(3):314-323. • Page, L.M., A.D. Cameron, and G.C. Clarke. 2001. Influence of overstorey basal area on density and growth of advance regeneration of Sitka spruce in variably thinned stands. Forest Ecology and Management 151(1-3):25-35. • Palik, B., R.J. Mitchell, S. Pecot, M. Battaglia, and M. Pu. 2003. Spatial distribution of overstory retention influences resources and growth of longleaf pine seedlings. Ecological Applications 13(3):674-686. • Pearson, G.A. 1936. Some Observations on the Reaction of Pine Seedlings to Shade. Ecology 17(2):270-276. • Rose, C.R., and P.S. Muir. 1997. Green-tree retention: consequences for timber production in forests of the western Cascades, Oregon. Ecological Applications 7(1):209-217. • Wagner, R.G., and S.R. Radosevich. 1991. Neighborhood predictors of interspecific competition in young Douglas-fir plantations. Canadian Journal of Forest Research 21(6):821-828. • Wampler, M. 1993. Growth of Douglas-fir Under Partial Overstory Retention. M.S. thesis, University of Washington, Seattle, WA.

  22. Thank You !

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