douglas-fir spacing trial at wind river
TRANSCRIPT
THE IMPACTS OF SPACING ON TREE GROWTH, MORTALITY AND TREE CROWN DEVELOPMENT
Sheel Bansal, Robert O. Curtis, Constance A. HarringtonUSDA Forest Service, Pacific Northwest Research Station
• Initial spacing of trees during planting has a strong influence on 1) timber production and on 2) wildlife and fish habitat.
• Strategic use of spacing can increase multifunctionality of forests to optimize production and habitat.
• Spacing effects: Competitive interaction, growth rates, crown structure, habitat, mortality rates, understory temperature and light levels, etc.
Introduction
Spacing StudyDesign• Planting date: 1981• Species: Douglas-fir (DF),
Western Hemlock (WH) or mixed
• Spacing distances: 1 – 6 mMeasurements• Measurements 32 years
after planting (2013)• On plots with DF only • Heights, diameters,
crown width, height to live crown
• After 32 years, spacings of 3 and 4 m were optimal for Douglas-fir timber volume production, whereas wider spacings increase canopy openness and individual tree size and vigor.
• The ideal spacing at planting for multifunctionality is dependent on management objectives, rotation period and planned thinnings. Wider initial spacings are more desirable for longer rotations as tree vigor is less impacted by tree to tree competition.
Conclusion
Spacing effects after 32 years
Sheel Bansal, Research EcologistOlympia Forestry Sciences Laboratory
Wind River Experimental Forest
The spacing that produces maximum volume depends on diameter cutoff used (4 or 20 cm).
Basal area (BA) and Stand Density Index (SDI) are greater at closer spacings.Note: SDI in metric unitsSDI (English)= 0.40*SDI(metric)
Very high mortality at 1 and 2 m spacings, but not much difference between 3, 4, 5 and 6 m spacings.
Heights were not affected by spacing.Diameter and quadratic mean diameter (QMD) increased with spacing.Note: H100 and D100 represent 100 tallest trees/ha
The amount of crown area per unit ground area (CA/GA) exceeds 1 (crown closure) between 4 and 5 m spacing.
crown closure
High live crown ratio (LCR) at wide spacings indicates trees have branches close to the ground.lower vigor
higher vigor
SpacingSpecies