Prediction of stand susceptibility and gypsy moth defoliation in Coastal Plain mixed pine-hardwoods

The European gypsy moth (Lymantria dispar L.) is an introduced defoliator that has become endemic in for- ests of the northeastern United States. During the last five decades, populations have continued to advance into the southeastern United States. Defoliation outbreaks continue to occur along the leading edge of the infestation, and the potential for extensive defoliation within southern forests remains. A field study was implemented in 1991 to determine the relationship between species composition and gypsy moth defoliation in Coastal Plain mixed pine-hardwood stands and to formulate a defoliation prediction model. Stands in both pine-oak and pine-sweetgum cover types were exten- sively defoliated during a single defoliation outbreak. Mean stand defoliation in the pine-oak type peaked at 42.6% in 1994, while mean defoliation in the pine-sweetgum type peaked at 32.8% in 1995. Defoliation intensity was signifi- cantly related to stand composition, with oaks and sweetgum being defoliated at the greatest intensities. Overall, pines were not heavily defoliated in either cover type. However, moderate to heavy defoliation of a small number of overstory pines was observed in some pine-oak stands and appeared to be due to a threshold level of oak defoliation (>80%). A nonlinear model for the prediction of mean total stand defoliation is also presented. Defoliation is predicted as a function of the number of gypsy moth egg masses, the number of years since the beginning of the outbreak, sus- ceptible species basal area, pine basal area, and total stand basal area. Resume : La spongieuse (Lymantria dispar L.) est un insecte defoliateur introduit qui est devenu endemique dans les forets du nord-est des Etats-Unis. Au cours des cinq dernieres decennies, les populations ont continue de progresser vers le sud-est des Etats-Unis. Des epidemies continuent a survenir le long du front de l'infestation et la possibilite subsiste qu'il y ait des defoliations severes dans les forets du sud. Une etude de terrain a ete mise en place en 1991 pour determiner la relation entre la composition en especes et la defoliation par la spongieuse dans les peuplements

[1]  J. McGraw,et al.  Within-population variation in response of red oak seedlings to herbivory by gypsy moth larvae , 1994 .

[2]  S. Cook,et al.  Oviposition and Pupal Survival of Gypsy Moth (Lepidoptera: Lymantriidae) in Virginia and North Carolina Pine-Hardwood Forests , 1994 .

[3]  M. Rossiter.  Use of a secondary host by non-outbreak populations of the gypsy moth. [Pinus rigida; Quercus spp; Lymantria dispar] , 1987 .

[4]  L. Douglass,et al.  Developmental and Reproductive Performance of the Gypsy Moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), on Selected Hosts Common to Mid-Atlantic and Southern Forests , 1983 .

[5]  R. Campbell,et al.  Forest Stand Responses to Defoliation by the Gypsy Moth , 1977 .

[6]  T. Jukes.  Defoliation by Gypsy Moth , 1971, Nature.

[7]  W. L. Baker.  Effect of Gypsy Moth Defoliation on Certain Forest Trees , 1941 .

[8]  C. Minott,et al.  Some Results of the Defoliation of trees , 1925 .

[9]  Kurt W. Gottschalk,et al.  Forest susceptibility to the gypsy moth. , 1997 .

[10]  Andrew M. Liebhold,et al.  Suitability of North American tree species to gypsy moth: a summary of field and laboratory tests. , 1995 .

[11]  V. Sit,et al.  CATALOGUE OF CURVES FOR CURVE FITTING , 1994 .

[12]  M. Montgomery.  Variation in the suitability of tree species for the gypsy moth , 1991 .

[13]  Kurt W. Gottschalk,et al.  Gypsy moth impacts in pine-hardwood mixtures , 1989 .

[14]  David A. Gansner,et al.  Rating forest stands for gypsy moth defoliation , 1986 .

[15]  P. W. Orr,et al.  Forest insect and disease conditions in the United States, 1978. , 1980 .

[16]  D. Houston.  Classifying forest susceptibility to gypsy moth defoliation. , 1979 .