The natural durability of 10 lesser known, commercially available Bolivian hardwoods to decay fungi was evaluated using a modified ASTM soil-block analysis for 12 weeks. The blocks were then retested for an additional 12 weeks to determine their level of decay resistance, as determined by percentage of weight loss. Astronium urundeuva, Caesalpinia cf. pluviosa, Schinopsis quebrachocolorado, and Tabebuia sp. (Iapacho group) were found to be highly resistant to decay; Amburana cearensis, Anadenanthera colubrina (syn: A. macrocarpa), Aspidosperma cylindrocarpon, Diplotropis purpurea, and Guibourtia chodatiana, resistant to decay; and Phyllostylon rhamnoides, moderately resistant to decay. We conclude that an extended soil-bottle test is an effective tool for assessing the level of natural durability of these and other tropical species

Green, Frederick

Miller, Regis B.

Stockman, Willy

Wiedenhoeft, Alex C.

Williams, R. Sam

English

Wood and Fiber Science (E-Journal)

WOOD AND FIBER SCIENCEMonday Jun 09 2003 10:30 AMAllen Press • DTPro Systemwood 35_304 Mp_429File # 04eeWood and Fiber Science, 35(3), 2003, pp. 429–433CHARACTERISTICS OF TEN TROPICAL HARDWOODS FROMCERTIFIED FORESTS IN BOLIVIA. PART II. NATURAL DURABILITYTO DECAY FUNGIRegis B. Miller1BotanistAlex C. WiedenhoeftBotanistR. Sam WilliamsSupervisory Research ChemistWilly StockmanBiological Science TechnicianandFrederick Green IIIMicrobiologistUSDA, Forest ServiceForest Products Laboratory1One Gifford Pinchot DriveMadison, WI 53726-2398(Received March 2002)ABSTRACTThe natural durability of 10 lesser known, commercially available Bolivian hardwoods to decayfungi was evaluated using a modified ASTM soil-block analysis for 12 weeks. The blocks were thenretested for an additional 12 weeks to determine their level of decay resistance, as determined bypercentage of weight loss. Astronium urundeuva, Caesalpinia cf. pluviosa, Schinopsis quebracho-colorado, and Tabebuia sp. (lapacho group) were found to be highly resistant to decay; Amburanacearensis, Anadenanthera colubrina (syn: A. macrocarpa), Aspidosperma cylindrocarpon, Diplotropispurpurea, and Guibourtia chodatiana, resistant to decay; and Phyllostylon rhamnoides, moderatelyresistant to decay. We conclude that an extended soil-bottle test is an effective tool for assessing thelevel of natural durability of these and other tropical species.Keywords: Natural durability, soil-block test, tropical hardwoods.INTRODUCTIONNatural durability, weathering characteristics,and dimensional changes are important proper-ties of wood for outdoor use. Much is knownabout some woods, like teak (Tectona grandisL.) and Honduras mahogany (Swietenia macro-1 The Forest Products Laboratory is maintained in co-operation with the University of Wisconsin. This articlewas written and prepared by U.S. Government employeeson official time, and it is therefore in the public domainand not subject to copyright.phylla King), but there are many gaps in ourknowledge about some lesser known or lesserused species. This is especially true for woodsfrom Bolivia, a country that has a large forestresource. Within the last 10 years, the develop-ment of this forest resource has expanded. Theinitial focus on harvesting mahogany (S. macro-phylla) has shifted to the utilization of manyspecies. To provide local land owners and op-erators of certified forests with information onweathering characteristics and decay resistance,we initiated a two-part project focused on 10430 WOOD AND FIBER SCIENCE, JULY 2003, V. 35(3)WOOD AND FIBER SCIENCEMonday Jun 09 2003 10:30 AMAllen Press • DTPro Systemwood 35_304 Mp_430File # 04eeBolivian hardwoods. In Part I, we studiedweathering characteristics and dimensionalchanges (Williams et al. 2001). The work re-ported here describes Part II, tests on decay re-sistance using a modified ASTM soil-blockanalysis (ASTM 1994).Information on the properties and charac-teristics of Bolivian hardwoods, including nat-ural resistance to decay fungi, is found in sev-eral publications. Chudnoff (1984), Berni et al.(1979), and Chichignoud et al. (1990) com-piled data on Latin American species; Teixeiraet al. (1988), IBDF (1981, 1988), and Mainieriand Chimelo (1989) focused on Brazilian spe-cies; and Gérard et al. (1996) studied timbersof Guyana. These reports provide data onsome Bolivian species, but most often presentdata on other species in the same genera. Inmost cases, it is not possible to determine ifthe data on decay resistance were derived fromsoil-block or long-term stake tests.Soil-block tests or other accelerated labo-ratory tests have been done on some Bolivianspecies growing in Peru and Paraguay. High-ley and Scheffer (1970) evaluated 30 Peruvianspecies, and Greenwood and Tainter (1980)evaluated 16 Paraguayan species. Others(Monteiro and de Freitas 1977; Cavalcante etal. 1978; Silverborg et al. 1970) evaluatedclosely related South American species, i.e.,species in the same genus. In the absence ofother critical data, results from species in thesame genus may suggest similar decay resis-tance if the woods are similar in other re-spects.EXPERIMENTALMaterialsHeartwood from one tree of each of 10 spe-cies was obtained from a certified forest in Bo-livia. The species were Amburana cearensis(Allemao) A. C. Smith (roble or ishpingo inPeru), Anadenanthera colubrina (Vell.) Bren-an (syn: A. macrocarpa (Benth.) Brenan) (cu-rupau or curupay), Aspidosperma cylindrocar-pon Muell. Arg. (jichituriqui), Astroniumurundeuva Engl. (cuchi), Caesalpinia cf. plu-viosa DC. (momoqui), Diplotropis purpurea(Rich.) Amsh. (sucupira), Guibourtia choda-tiana (Hassl.) J. Leonard (sirari), Phyllostylonrhamnoides (Poisson) Taubert (cuta), Schin-opsis quebracho-colorado (Schidl.) F. Barkleyand T. Meyer (soto or quebracho), and Tabe-buia sp. (lapacho group, tajibo or ipe). Redpine (Pinus resinosa Ait.) and yellow birch(Betula alleghaniensis Britt.) were used forsapwood control samples.The fungi used in the tests were pure cul-tures of two brown-rot fungi (Tyromyces pal-ustris (Berk. and M.A. Curtis) Murrill, MAD6137) and Gloeophyllum trabeum (Pers.:Fr.)Murrill, MAD 617) and one white-rot fungus(Trametes versicolor (L.:Fr.) Pilat, MAD 697).METHODSWe used a modified ASTM D-2017 soil-block experimental method (ASTM 1994).Two matched sets of the Bolivian heartwoodsamples (19- by 19- by 19-mm blocks) andcontrol sapwood samples were prepared. Eachset contained four replicates for a total of eightsamples per species. Both sets were placed instandard soil-block bottles (two blocks perbottle) in a decay chamber (278C and 80% rel-ative humidity) and exposed for 12 weeks topure cultures of the decay fungi. After 12weeks, one set of samples was removed, oven-dried at 808C to a constant weight, andweighed to determine weight loss. The oven-dried samples were then steam-sterilized andtransferred to freshly prepared soil-block bot-tles. The other set of samples was not oven-dried; these samples were steam-sterilized andtransferred to freshly prepared soil-block bot-tles to extend the test period to 24 weeks. Bothsets were then exposed for a second 12-weekperiod, after which they were oven-dried andweighed.RESULTS AND DISCUSSIONThe average percentages of weight loss andstandard deviation for each species and fungusafter 12 and 24 weeks of exposure are shownin Table 1 and Figs. 1 to 3. Following the ex-431Miller et al.—CHARACTERISITICS OF THE TEN TROPICAL HARDWOODS IN BOLIVIA. PART IIWOOD AND FIBER SCIENCEMonday Jun 09 2003 10:30 AMAllen Press • DTPro Systemwood 35_304 Mp_431File # 04eeTABLE 1. Percentage of weight loss for wood species after 12 and 24 weeks of exposure to decay fungi in soil-blocktests.aSpeciesG. trabeumMAD-61712 wk 24 wkT. palustrisTYP-613712 wk 24 wkT. versicolorMAD-69712 wk 24 wkPinus resinosa (control)Betula alleghaniensis (control)Amburana caerensis58.4(9.3)40.6(4.0)1.9(0.6)——2.4(1.0)31.4(7.5)34.8(6.1)13.4(3.2)——21.3(5.2)9.5(1.4)38.6(3.0)12.2(6.0)——21.6(8.4)Anadenanthera colubrinaAspidosperma cylindrocarponAstronium urundeuva2.3(1.4)6.9(1.6)0.2(0.1)2.2(2.0)9.6(1.8)21.2(1.5)10.7(4.9)16.8(1.6)0.1(0.2)23.1(7.4)33.0(3.6)20.5(0.4)1.9(0.3)1.0(0.2)1.5(1.3)2.2(7.0)3.2(1.1)0.6(1.4)Caesalpinia cf. pluviosaDiplotropis purpureaGuibourtia chodatiana2.8(0.3)1.8(0.0)7.9(1.1)3.1(0.3)2.3(0.5)25.3(6.1)4.5(0.7)13.9(1.3)17.1(1.0)7.7(1.2)21.3(1.8)37.0(3.6)4.0(0.7)3.0(0.2)6.8(3.8)6.5(0.8)3.9(0.9)16.6(7.1)Phyllostylon rhamnoidesSchinopsis quebracho-coloradoTabebuia sp. (lapacho group)29.9(5.3)1.2(0.4)1.6(0.2)38.5(2.7)0.7(0.7)1.6(0.3)32.5(2.2)0.6(0.4)3.8(3.8)35.6(3.6)4.3(5.4)5.2(5.9)5.7(1.9)1.2(0.3)1.9(0.4)12.41(2.6)0.6(0.3)2.2(0.7)a Values in parentheses are standard deviation. n 5 8 for each fungus-wood pairing.FIG. 1. Weight loss after 12 and 24 weeks of exposureto Gloeophyllum trabeum (MAD 617).FIG. 2. Weight loss after 12 and 24 weeks of exposureto Tyromyces palustris (MAD 6137).ample of Highley and Scheffer (1970), weseparated the species into four decay resis-tance classes: highly resistant, 0–10% weightloss; resistant, 11%–24%; moderately resis-tant, 25%–44%; and nonresistant, $45%. Thisarbitrary decay resistance classification is sug-gested in the ASTM standards (ASTM 1994)and has also been used by Clark (1969) andothers. For each species, we used the most de-structive fungus as the determinant of resis-tance (Highley and Scheffer 1970).After 12 weeks of exposure, all Bolivianspecies had less than 13% weight loss and432 WOOD AND FIBER SCIENCE, JULY 2003, V. 35(3)WOOD AND FIBER SCIENCEMonday Jun 09 2003 10:30 AMAllen Press • DTPro Systemwood 35_304 Mp_432File # 04eeFIG. 3. Weight loss after 12 and 24 weeks of exposureto Trametes versicolor (MAD 697).TABLE 2. Decay resistance of wood species after 12 weeks of fungal exposure.aSpecies Decay resistance classbAmburana caerensisAnadenanthera colubrinaAspidosperma cylindrocarponAstronium urundeuvaCaesalpinia cf. pluviosaResistantResistantResistantHighly resistantHighly resistantDiplotropis purpureaGuibourtia chodatianaPhyllostylon rhamnoidesSchinopsis quebracho-coloradoTabebuia sp. (lapacho group)ResistantResistantModerately resistantHighly resistantHighly resistanta For each species, the most destructive fungus was used as the determinant of resistance (Highly and Scheffer 1970).b Highly resistant, 0–10% weight loss; resistant, 11%–24%; moderately resistant, 25%–44%; and nonresistant, $45%.most had less than 10% weight loss as a resultof decay by the white-rot fungus Trametesversicolor. For both brown-rot fungi, the con-trols and Phyllostylon rhamnoides had at least30% weight loss. For all other Bolivian spe-cies, Tyromyces palustris caused less than18% weight loss and Gloeophyllum trabeumless than 10% weight loss. Table 2 lists thedecay resistance ratings of the Bolivian spe-cies after 12 weeks of exposure.Because some species were suspected to bevery resistant to decay, we designed the studyto continue for more than the standard 12weeks. If soil-block bottles are incubated for24 weeks, they lose moisture, rendering thefungi less active. To make the test as severeas possible, we used two back-to-back 12-week tests. The two sets of samples for the24-week test—one set oven-dried, weighed,and steam-sterilized; the other set only-steam-sterilized—showed similar weight losses.However, the oven-dried samples cracked,checked, and in some cases fell apart duringdrying. For future 24-week studies, we rec-ommend that samples be transferred from 12-week-old bottles to fresh bottles without oven-drying. The sapwood control blocks were toodecayed to be replaced into bottles for the sec-ond 12-week period.Only two species showed a difference in de-cay resistance after 24 weeks compared withthat after 12 weeks. Guibortia chodatiana andAspidosperma cylindrocarpon shifted from theresistant to the moderately resistant category.We compared our soil-block test results toreports in the literature. In some cases, resultsfrom laboratory, graveyard, or stake tests arereported; more often, the only sources of in-formation are general observations and expe-rience in service. Very little information wasavailable for Caesalpinia pluviosa, Guibourtiachodatiana, and Phyllostylon rhamnoides. ForAspidosperma cylindrocarpon, we comparedour results with results from a soil-block test(Highley and Scheffer 1970). In both studies,the white-rot fungus T. versicolor, MAD 697,and the brown-rot fungus G. trabeum, MAD617, caused less than 10% weight loss. In ourstudy, however, the very aggressive brown-rotfungus T. palustris, MAD 6137, caused 17%weight loss. In contrast, in the 1970 study, Po-433Miller et al.—CHARACTERISITICS OF THE TEN TROPICAL HARDWOODS IN BOLIVIA. PART IIWOOD AND FIBER SCIENCEMonday Jun 09 2003 10:30 AMAllen Press • DTPro Systemwood 35_304 Mp_433File # 04eeria monticola (syn. Postia placenta) (MAD698) caused only 8% weight loss. In a similarstudy, Monteiro and de Freitas (1997) foundthat Aspidosperma polyneuron Mull. Arg. andan unidentified species of Astronium fromBrazil were very decay resistant. Greenwoodand Tainter (1980) evaluated the decay resis-tance of 16 species from Paraguay using soil-block tests. They also found that species ofAstronium, Anadenanthera, Aspidosperma,and Tabebuia (lapacho group) were highly re-sistant to decay.The use of a second 12-week period of ex-posure to decay fungi in soil-block bottles isan effective method of separating the decay-resistance ratings of durable tropical timbers.Species that show virtually no weight loss af-ter 12 weeks do not change decay resistancecategories. Those species that border betweentwo categories can be more accurately classi-fied after a second 12-week exposure period.REFERENCESAMERICAN SOCIETY FOR TESTING AND MATERIALS. (ASTM)1994. D 2017. Standard test method for wood preser-vatives by laboratory soil-block cultures. The ASTMBook of Standards. ASTM, Philadelphia, PA.BERNI, C. A., E. BOLZA, AND F. J. CHRISTENSEN. 1979.South American timbers—Characteristics, properties,and uses of 190 species. Commonwealth Sci. and Ind.Res. Organization (CSIRO), Div. of Bldg. Res., Mel-bourne, Australia.CAVALCANTE, M. S., R. G. MONTAGNA, S. MILANO, ANDE. S. FOSCO MUCCI. 1978. Durabilidade natural de mad-eiras em contato com o solo. Bol. Técn. IF, São Paulo,29:1–15.CHICHIGNOUD, M., G. DÉON, P. DÉTIENNE, B. PARANT, ANDP. VANTOMME. 1990. Tropical timber atlas of LatinAmerica. ITTO/CIRAD-CTFT, Yokohama/Nogent-sur-Marne, Japan/France.CHUDNOFF, M. 1984. Tropical timbers of the world. Agric.Handbook No. 607. USDA Forest Service, Washington,DC. 464 pp.CLARK, J. W. 1969. Natural decay resistance of fifteenexotic woods imported for exterior use. Res. Pap. FPL-103, USDA, Forest Serv., Forest Prod. Lab., Madison,WI. 5 pp.GÉRARD, J., R. B. MILLER, AND B. J. H. TER WELLE. 1996.Major timber trees of Guyana: Timber characteristicsand utilization. Tropenbos series 15, The TropenbosFoundation, Wageningen, The Netherlands. 224 pp.GREENWOOD, B. F. DE, AND F. H. TAINTER. 1980. Compar-ative decay resistance of Paraguayan woods. Turrialba30:137–139.HIGHLEY, T. L., AND T. C. SCHEFFER. 1970. Natural decayresistance of 30 Peruvian woods. Res. Pap. FPL-143,U.S. Department of Agriculture, Forest Service, ForestProducts Laboratory, Madison, WI. 4 pp.IBDF. 1981. Madeiras da Amazônia: Cracterı́sticas e util-ização, vol. I. Floresta Nacional do Tapajós. CNPq, Bra-sı́lia, Brazil.. 1988. Madeiras da Amazônia: Caracterı́sticas eutilização, vol. II. Estaçâo experimental de Curúa–Una.CNPq, Brası́lia, Brazil.MAINIERI, C., AND J. P. CHIMELO. 1989. Fichas de carac-terı́sticas das madereiras Brasileiras. Instituto de Pes-quisas Tecnològicas (IPT), Div. de Madeiras, São Paulo,Brazil.MONTEIRO, M. B. B., AND A. R. DE FREITAS. 1997. Accel-erated laboratory test methods for the evaluation of nat-ural decay resistance of woods. Revista-Arvore 21:555–561.SILVERBORG, S. B., L. DE MAYORCA, AND J. CONEJOS. 1970.Durabilidad relativa de algunas maderas Venezolanas.Revista Forestal Venezolana 13:61–72.TEIXEIRA, D. E., M. A. E. SANTANA, AND M. R. DE SOUZA.1988. Amazonian timbers for the international market.ITTO Tech. Series 1. Brazilian Institute for Forestry De-velopment (IBDF) and International Tropical TimberOrganization (ITTO), Brası́lia, Brazil.WILLIAMS, R. S., R. B. MILLER, AND J. GANGSTAD. 2001.Characteristics of ten tropical hardwoods from certifiedforests in Bolivia, part 1. Weathering characteristics anddimensional change. Wood Fiber Sci. 33:618–626.

Characteristics of Ten Tropical Hardwoods from Certified Forests in Bolivia. Part II. Natural Durability to Decay Fungi

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Characteristics of Ten Tropical Hardwoods from Certified Forests in Bolivia. Part II. Natural Durability to Decay Fungi

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