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METHODS The study was installed in a mixed conifer stand (elevation - 1460 m) in northeastern Oregon. On June 29, 1993, seven Douglas-fir and seven western larch were selected from an area of less than 1 ha. The trees were chosen based on similarities in size and lack of any visible injuries or disease. Three inoculation sites were established equidistant around the circumference of each tree at dbh (1.4 m height). The three treatments that were randomly assigned to the inoculation sites were: (1) sterile wound, (2) L. abietinum, and (3) O. pseudotsugae. At each inoculation site, a 1.2-cm diameter hole was drilled to the sapwood surface with a sterile bit. For the sterile wound, a cotton plug was placed in the hole that was then covered with duct tape. For the fungal inoculations, a small agar plug containing the appropriate fungus was placed in the hole that was then similarly covered. The fungi used in the study had been isolated from Douglas-fir beetles collected in British Columbia, Canada (Solheim unpubl.). On August 25, 1993, the outer bark covering each inoculation site was removed and the length of the necrotic lesion on the phloem surface was measured. The mean dbh for trees of each species were compared by a t-test. Lesion length was subjected to analysis of variance for a split-plot design with tree species representing whole plots and fungal inoculation representing subplots. RESULTS There was no significant difference (P < 0.19) in dbh between Douglas-fir (mean = 51.0 cm) and western larch (mean = 48.8 cm). The tree species x treatment interaction was significant (F = 3.29; P < 0.05) for lesion length. For both tree species, inoculation with either fungus resulted in a larger lesion than that produced by a sterile wound (Fig. 1). The length of the lesions induced by a sterile wound or inoculation with O. pseudotsugae did not differ between tree species, but the lesion induced by inoculation with L. abietinum was significantly shorter in western larch than in Douglas-fir (Fig. 1). DISCUSSION There were no obvious differences in the general appearance of lesions (i.e., intensity of resin accumulation, radial growth, etc.) between tree species, so lesion length should provide a relatively accurate indication of fungal growth within the phloem of the host trees. The smaller lesions produced by western larch in response to L. abietinum may reflect a more rapid and effective defensive reaction to the fungus. These results suggest that L. abietinum is not as well adapted to utilize western larch as a host compared with Douglas-fir. If L. abietinum is critical to the survival of Douglas-fir beetle brood in live host trees, then this may help to explain the complete mortality of brood in western larch. In contrast, there was no difference in the induced response to O. pseudotsugae between the two tree species. Our results must be interpreted cautiously since we have only measured lesion length in phloem tissue. Lesion length is not always directly correlated to pathogenicity (Solheim 1988). Fungal growth and tree response may be quite different in the xylem compared with the phloem. However, the difference in response to fungal inoculations that we observed suggests that further research on the host tree-fungus interactions in this system would be worthwhile. The significance of these results will only become apparent when we learn more about the role that these fungi play in the population dynamics of the Douglas-fir beetle. SUMMARY There was no difference in lesion length at the phloem surface between Douglas-fir and western larch following sterile wounds or inoculation with O. pseudotsugae. However, lesion length following inoculation with L. abietinurn was significantly shorter in western larch compared with Douglas-fir. These results may help to explain the lack of Douglas-fir beetle brood survival in western larch. 225
5O 40- Douglas-fir a a Western larch a E E b 30- J:E E "-- C E 20o (_ _J 10- 0 Wound L. ab/et/num O. pseudotsugae Treatment Figure 1.--Mean length of the induced lesion at the phloem surface following sterile wounding or fungal inoculation in Douglas-fir and western larch (n=7). Bars with the same letter are not significantly different (P = 0.05). LITERATURE CITED BERRYMAN, A.A. 1972. Resistance of conifers to invasion of bark beetle-fungus associations. BioScience 22: 598-602. CHRISTIANSEN, E. and HORNTVEDT, R. 1983. Combined Ips/Ceratocystis attack on Norway spruce, and defensive mechanisms of the trees. Z. Ang. Entomol. 96:110-118. CORNELIUS, R.O. 1955. How forest pests upset management plans in the Douglas-fir region. J. For. 53:71 I-713. FURNISS, M.M. and ORR, P.W. 1978. Douglas-fir beetle. For. Insect & Dis. Leafl. 5. Washington, DC" U.S. Department of Agriculture, Forest Service. FURNISS, M.M., MCGREGOR, M.D., FOILES, M.W., and PARTRIDGE, A.D. 1979. Chronology and characteristics of a Douglas-fir beetle outbreak in northern Idaho. Gen. Tech. Rep. INT-59. Ogden UT: U.S. Department of Agriculture, Forest Service. 226 : ii
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DYNAMICS OF FOREST HERBIVORY: QUEST
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TABLE OF CONTENTS Seeking The Rules
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32. Companion planting of the nitro
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GRIMALSKY, ¥.I., Research Institut
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POUTTU, ANTTI, Finnish Forest Resea
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persist in mature leaves and affect
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THE SINK-SOURCE HYPOTHESIS: TYPE AN
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late season defoliation decreases t
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BLANCHE, C.A., LORIO, EL., Jr., SOM
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NIEMELA, R, TUOMI, J,, and LOJANDER
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induced reactions have been studied
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summer, but the other sawfly specie
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LARSSON, S., BJ(_RKMAN, C., and GRE
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STAND AND LANDSCAPE DIVERSITY AS A
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not related to resistance to the se
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In contrast to the situation in eas
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ROOT, R.B. 1973. Organization of a
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We tlhus neglect two potential sour
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c__ c__ 1T1 Ill a) a) 0 0 0 e 1 o e
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c_ >l.s S S S m N < DN DN < D c DN
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:hen k > 0 suggest that the cue or
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oth as protective weapons and as po
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DEFENSE THEORIES AND BIRCH RESISTAN
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P 45 A L 40 A T 35 A B 30 I L 25 I
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However, hares showed strong prefer
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DUGLE, J.A. 1966. A taxonomic study
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accommodate findings related to mic
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Table l.--Mean ±S.E. area eaten by
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Sulfhydryl-Disulfide Mechanisms In
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Iraa prior experimental analysis of
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FRAZIER, J.L. and HEITZ, J.R. 1975.
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REICHARD, R 1993. From RNA to DNA,
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; trees, and between and within ind
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Encapsulated objects are data struc
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_re3.--The Lignum model can be cont
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SEVERE DEFOLIATION Tree Fine Root +
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RUMBAUGH, J., BLAHA, M., PREMERLANI
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oo0 a b ol ¢' _achiman_i ()® 1,eA
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1000 Conspicuous Defo i at ion 100
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2.oo 2.oo o t 4 t ¢._ e'- 1.80 1.8
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Qualitative Changes in [,eaves and
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t00 2 Yr 1 Yr o_ 80 Treatment Treat
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Table 2.--Body size of Q. purzctate
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06 b AddedBSA < 04 _ 2rag -'=' i:3
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Severe Defol iat ion Site-A 1993 _
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KAMATA, N. and IGARASHI, M. 1995b.
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enclosure %r 20 post-diapausing sec
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2,500 F 000 F NF NF b _7 a _;_ a _7
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8O D 09 i 4,'.) F AS4L a Z___7 2o !
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2,500 _ st2-st4 El st5 0 st6 [_ pup
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96 SLANSKY, E, Jr. 1990. Insect nut
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later, we selected one more floweri
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Table 2.---Mean spruce budworm perf
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Table 3..--Mean spruce budworm perf
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FOLIVORE FEEDING ON MALE CONIFER FL
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Table 3.--Lymantria monacha prefere
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500- 400- i 300 v ¢ m a 200- I00 L
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From the point of view of trees, th
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THE BLACKMARGINED APHID AS A KEYSTO
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Wood et al. (1987) report that M. c
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MIZELL, R.E 1991. Pesticides and be
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METHODS Study Site The study took p
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the samples. Fertilization had subs
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Table 2.--Percent nutrient content
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Some tree responses to fertilizatio
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PHYTOCHEMICAL PROTECTION AND NATURA
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Indirect effects of abiotic factors
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HUNTER, M.D. and PRICE, P.W. 1992.
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A° ADDITIVE C. HYBRID SUSCEPTIBILI
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Galls, leaf miners, or leaf folds w
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Table 2.--Summary of the hypotheses
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the inheritance patterns of seconda
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FLOATE, K.D. and WHITHAM, T.G. 1993
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Elements of the Suitability/Defense
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Table l.--Comparing the mean number
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ACKNOWLEDGEMENTS The authors sincer
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SINGH, D.R 1986_ Breeding for resis
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The objectives of this presentation
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Table 1.--Average weevil attack on
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1977, Kline and Mitchell 1979, Wood
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Further research is underway to cla
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A SUGI CLONE HIGHLY PALATABLE TO HA
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RESULTS Seasonal Stability of Palat
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-
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OGAWA, A., NAGATA, Y., and SUKENO,
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MATERIALS AND METHODS Field Work In
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Laboratory Procedures The week afte
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E 120 Nogent-sur-Vernisson Remnings
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Interdependence Between Reaction Zo
Page 184 and 185: alance hypothesis (Lorio 1986) cann
Page 186 and 187: SOLHEIM, H., LANGSTROM, B., and HEL
Page 188 and 189: In a second experiment, three 30-ye
Page 190 and 191: Considering biochemical pathways, i
Page 192 and 193: - = 120 N /'_" =40 1/ _ j Days 0 _
Page 194 and 195: BIGGS, A.R. 1985. Suberized boundar
Page 196 and 197: DIFFERENTIAL SUSCEPTIBILITY OF WHIT
Page 198 and 199: Table 2.--Mortality of white fir pr
Page 200 and 201: Results from the geographic range p
Page 202 and 203: esulting seedlings were then rooted
Page 204 and 205: -0.2 0 5 82. _j -0,4 e a a a D4 E I
Page 206 and 207: 1960, Kalkstein 1976). Increased su
Page 208 and 209: RYAN, B.F., JOtNER, B.L., and RYAN,
Page 210 and 211: It is seldom feasible to control wa
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Page 214 and 215: Only recently have we conducted stu
Page 216 and 217: esistance to beetle attack. Another
Page 218 and 219: LORIO, EL., Jr'. and HODGES, J.D. 1
Page 220 and 221: EFFECTS OF ROOT INHABITING INSECT-F
Page 222 and 223: OCCURRENCE OF ROOT AND STEM SUBCORT
Page 224 and 225: ]Predisposition of Root-infected Tr
Page 226 and 227: chemistry associated with root colo
Page 228 and 229: Implications to Natural Resource Ma
Page 230 and 231: KLEPZIG, K.D., RAFFA, K.F., and SMA
Page 232 and 233: RAFFA, K.F., PHILLIPS, T., and SALO
Page 236 and 237: FURNISS, M.M., LIVINGSTON, R.L., an
Page 238 and 239: METHODS In the spring and summer of
Page 240 and 241: The importance of a compound as a r
Page 242 and 243: WERNER, R.A. 1995. Toxicity and rep
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Page 246 and 247: Table 1.--Summary data for the 26 p
Page 248 and 249: One weakness of using data from gen
Page 250 and 251: Lower Peninsula (populations 14-26)
Page 252 and 253: AUCLAIR, A.ND., WORREST, R.C., LACH
Page 254 and 255: KELLOMAKI, S., HANNINEN, H., and KO
Page 256 and 257: WARGO, RM. and HAACK, R.A. 1991. Un
Page 258 and 259: investigation. Sampling was done on
Page 260 and 261: Figure 2.--Changes in protein preci
Page 262 and 263: q) J 400 T J ! i i i i o control tr
Page 264 and 265: attacked trees than in control tree
Page 266 and 267: ACIDIC DEPOSITION, DROUGHT, AND INS
Page 268 and 269: Table 1.--Impact of acidic fog upon
Page 270 and 271: MENGEL, K., BREININGER, T., and LUT
Page 272 and 273: THE RESISTANCE OF SCOTCH PINE TO DE
Page 274 and 275: EXPERIMENTAL METHODS Experiments we
Page 276 and 277: C w Q. 1,200 1,000 o 800 C_ --- 600
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Page 280 and 281: FONTAtNE, R.G. 1985. Forty years of
Page 282 and 283: Host Defenses An important componen
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Functional Heterogeneity of Forest
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The Connectivity Index (CI). The CI
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FUNCTIONAL HETEROGENEITYANALYSIS :
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The Modified Hazard Map. The next l
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systems facilitate mapping of fores
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KOLASA, J. and ROLLO, C.D. 1991. In
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) i,i_i)i_)i_i_ U.S. Departme_]t of
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