PROPERTIES OF PLANTATION GROWN KOA (ACACIA KOA A. GRAY )

Transcription

1 PROPERTIES OF PLANTATION GROWN KOA (ACACIA KOA A. GRAY ) Brian H. Bond 1, Ian Wilton 2 and Nick S. Dudley 3 1 Department of Sustainable Biomaterials, Virginia Tech, 2 Exchange Student, and 3 Hawaiian Agricultural Research Center 3 Hawaii Agriculture Research Center

2 Introduction In Hawaii, Koa (Acacia koa) is a valuable tree species economically, ecologically, and culturally Endemic to Hawaii Used in furniture, cabinetry, musical instruments, and a wide variety of other decorative and craft products

3 Value of Lumber High valued lumber specie Average prices of $15.00 U.S. per bdft Premium instrument grade with vertical grain and heavy figured material can sell for over $100 U.S. per bdft Important features Color (heartwood) Figure.77 Board Feet Or $84/bd ft. 1.7 Board Feet Or $162/bd ft.

4 Examples of Variability and Grade

5 Problem Statement Limited supply Sources of koa are diminishing No harvesting of koa is currently permitted on state owned land in Hawaii Potential Solution Koa has been identified as adaptable to plantation management Plantation koa could theoretically become a substitute source Presently little is known about the properties of plantationgrown koa Planted koa will serve as a substitute resource only if properties that add value are present.

6 Objectives Determine the heartwood/sapwood ratios, specific gravity, hardness and for Hawaiian plantation-grown koa and compare them to published data from natural grown material

7 Methods Nine plantation-grown koa trees in Hawaii were harvested by HARC in trees five years of age 2 trees nine years of age Samples were prepared and mailed to Blacksburg, VA All were then allowed to reach an equilibrium at 12% EMC

8 Methods: Heartwood/Sapwood Discs were sanded and photographed Color and florescence Digital image analysis (ImageJ64) was then used to measure the percent of heartwood and sapwood within each cross section Visual and software assisted

9 Difficulties Measuring Heart/Sapwood Confusion with stain caused by the vascular wilt fungus Fusarium oxysporum

10 Methods: Specific Gravity/Density, Hardness Sections for each tree were then prepared and then tested for specific gravity (ASTM 2395) and hardness (ASTM D143) Four samples for each piece were taken Two sapwood Two heartwood Subsamples were cut and scanned using a QTRS-01X Tree Ring Analyzer to measure density variation from the bark to the pith and within the entire cross section Data was then compared to published values, when available

11 Results 5-Year-Old Plantation Koa 73% Sapwood 27% Heartwood

12 9-Year-Old Plantation Koa 23% Sapwood 77% Heartwood

13 Percent Results Percent Sapwood and Heartwood % Sapwood % Heartwood #10 R16 C15 #10 R7 C2 #15 R17 C6 #3 R15 C1 #5 R10 C3 #5 R12 C7 #5 R15 C # #2 Sample

14 Results Specific Gravity at 12% MC 0.52 Sample Average 0.55 for heartwood for sapwood 1 1 No statistical difference Values from literature: 0.55 (Skolmen, 1974; Alden 1995; and FPL, 2010) 0.46 (Gerry 1955)

15 Specific Gravity Results 0.60 Specific Gravity - (12%MC) Sapwood Heartwood #10 R16 C15 #10 R7 C2 #15 R17 C6 #3 R15 C1 #5 R10 C3 #5 R12 C7 #5 R15 C # #2 Sample

16 Results Density Ranged from kg/m average 96 stdv. Published values of density kg/m 3 Measurement criteria not reported (%MC)

17 Density Variation Large variability from bark to pith Within and between samples 5-year old

18 Density Variation 9-year-old

19 Results: Hardness Hardness Average hardness was 786 Large variation (standard deviation 303 lb) Min. 402 Max No statistical difference between sapwood and heartwood Varied between samples Reported values at 12% MC ,011 2 lbs 1 Gerry, FPL, 2010

20 Inch Pounds Measured at 12% MC Results Hardness 1800 Hardness (in. lb.) #10 R16 C15 #10 R7 C2 #15 R17 C6 #3 R15 C1 #5 R10 C3 #5 R12 C7 #5 R15 C # #2 Sample

21 Results Large within sample variability

22 Summary Heartwood/Sapwood 5 year old trees 73% Sapwood and 26 heartwood 9 year old trees 23% Sapwood and 77% heartwood Specific Gravity 0.52 average Between reported values No relationship found between S.G. and heartwood/sapwood Hardness Average was 786 lbs Lower than reported values Large variations found within and between samples

23 Future Work Determine if there is a relationship between color and density The Hawaiian koa wood classification system appears to be based on a relationship between color and density Determine shrinkage coefficients, MOE and MOR Compare to published values

24 Acknowledgements HARC: Maunawili Experiment Station Ian Wilton N.S. Dudley Tyler Jones