Relationships between forest Relationships between forest structure, understorey light structure, understorey light and regeneration in complex and regeneration in complex Douglas-fir dominated stands Douglas-fir dominated stands in south-eastern British in south-eastern British Columbia Columbia Kyle Lochhead and Phil Comeau University of Alberta June 10 th , 2012
19
Embed
Relationships between forest structure, understorey light and regeneration in complex Douglas-fir dominated stands in south-eastern British Columbia Kyle.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Relationships between forest Relationships between forest structure, understorey light and structure, understorey light and
regeneration in complex Douglas-fir regeneration in complex Douglas-fir dominated stands in south-eastern dominated stands in south-eastern
British ColumbiaBritish Columbia
Kyle Lochhead and Phil ComeauUniversity of Alberta
June 10th, 2012
. . . . Love for the western US
Relationships between forest Relationships between forest structure, understorey light and structure, understorey light and
regeneration in complex Douglas-fir regeneration in complex Douglas-fir dominated stands in south-eastern dominated stands in south-eastern
British ColumbiaBritish Columbia
Kyle Lochhead and Phil ComeauUniversity of Alberta
June 10th, 2012
Interior Douglas FirInterior Douglas Fir• Warm (1.6 - 9.5°C) and
Dry (300 – 750 mm)
• Fd – Lw – Pl
• Fire dominated
• Large openings – Frost
• Mule deer
• Light requirements of Fd (coast); >20% survive, morphology < 40%; Fd (interior) found in 5%
StructureStructure
Characterizing light levels in the understory
• Many studies indicate that stand characteristics such as basal area (Hale 2003), SDI (Vales and Bunnell 1988), Relative Density (Comeau and Heineman 2003) can be used to predict light levels
Study SiteStudy Site
• IDFdm2• Mixed conifer
– Fd, Lw, Pl, PP
• Fire occurred 120 yrs– Lw is over 200 yrs
• Harvested in 1994• Selection harvesting
with differing residual basal areas
Experimental DesignExperimental Design
• CRD with subsampling• 4 replicates of 4 treatments
of target residual basal area (m2/ha): 8, 16, 24, and unharvested (~37 m2/ha)
• Height growth is slow (<20% fully sky)– 2.3 to 6.8 cm
• Treatment differences– Small (p=0.47), Medium (p =
0.56), Large (p = 0.36)
• Average 5 year leader length: R2: 31.9 - 63.3% DIFN and N best
• Abundance: Light is key
At the microsite-scaleAt the microsite-scale
• Structural estimators capture < 55 (28)% – Measuring diffuse light– Small plot sizes (40% full sky in open plots)– Spatial information
• Covariates – non collinear, Dq positively related to light
• Effect of small trees (i) per unit basal area MAY have greater leaf area (ii) crowns closer to measurement point (iii) clumps
• How does this fit in with size-density relationships?
Light and size-densityLight and size-density
• Uneven-aged – Dq can range with the same N, estimate of skewness is needed
• SDI* deals with skewness and assumes additively but in this empirical study proved similar to SDI– Truncation of smaller classes (Ducey 2009)
• Sterba and Monserud (1993) – Flatter slope– This slope is not constant- often curvi-linear, other factors
• At the microsite - individual weight G (DBH2), SDI* (DBH1.6), sum D (DBH1) and N (DBH0)
ConclusionsConclusions
• Light availability is variable at the microsite
• The linkage between management at the stand level and microsite level– Use a growth model or … use bigger plots,
include spatial info, size-density relationships with structure
• RBA below 24 m2/ha promote regeneration
Thank-you
Funding for this research provided by B.C. Ministry of Forests and RangeAssistance from Teresa Newsome and Michaela Waterhouse is gratefully acknowledged