Growth of Sugar Maple (Acer saccharum Marsh.) after Ice Storm Damage and Forest Tent Caterpillar (Malacosoma disstria Hubner) Defoliation

The January 1998 ice storm broke off tree crowns across a wide geographic area in northeastern North America, and forest tent caterpillar (Malacosoma disstria Hubner) defoliated some of the same stands in 2004–2007. We assessed the post-event growth responses of upper canopy sugar maples (Acersaccharum Marsh.) in previously thinned and recently rehabilitated even-aged northern hardwood stands in New York State, USA. Cores from ice-storm-damaged trees showed an initial radial growth reduction, a recovery after one year, and an increase to or above pre-storm levels after three years. A later forest tent caterpillar defoliation in the same stand caused a second reduction of growth, and another recovery after one year. We observed greater post-storm radial growth on trees released by a post-ice storm rehabilitation treatment than in the untreated control, with growth exceeding pre-storm rates. Cores from another site thinned 38 years earlier and impacted only by the forest tent caterpillar showed a more moderate growth reduction, and a prompt but smaller post-defoliation growth response than among trees affected by both the ice storm and defoliation. Findings reflect the potential for growth of upper canopy sugar maple trees to recover after a single or two closely occurring crown disturbances, and provide guidance to managers who must decide about removing or continuing to manage stands after similar kinds of ice storm damage or defoliation.

Red alder defense mechanisms against western tent caterpillar defoliation

Red alder (Alnus rubra Bong.) is a tree of high economic and ecological importance but subject to severe defoliation during episodic outbreaks of tent caterpillars (Malacosoma spp.). We evaluated variation in western tent caterpillar (M. californicum Packard, 1864) (WTC) resistance among and within red alder populations and clones, and investigated potential defense mechanisms. Bioassay feeding trials were conducted with WTC on 20 red alder clones from 10 provenances (two clones per provenance). Phenology and quality of red alder leaves were analyzed to determine if budburst, leaf chemical content, water content or physical traits are determinants of WTC preference. Alder clones differed in percent leaf area eaten by WTC and in leaf defense traits. The concentrations of total phenolics, condensed tannin and the diarylheptanoid oregonin negatively correlated with the percent leaf area eaten by the caterpillars, and a potential threshold was observed, above which the concentration of each of the chemicals appeared to reduce WTC feeding. Particularly, foliar concentrations of oregonin greater than 20 % of leaf dry weight were consistently associated with reduced feeding. The effects of oregonin concentration in red alder leaves on tent caterpillar feeding is a novel finding.

Distinguishing eastern North American forest moth pests by wing-scale ultrastructure: potential applications in paleoecology

The use of fossil moth wing scales has recently been introduced as a new method to reconstruct population histories of lepidopterans and provide a proxy for insect disturbance. We investigated the potential for using wing-scale ultrastructure to distinguish between the five most common outbreak species of moth pests in eastern North America: spruce budworm ( Choristoneura fumiferana Clemens), hemlock looper ( Lambdina fiscellaria Guenée), forest tent caterpillar ( Malacosoma disstria Hübner), blackheaded budworm ( Acleris variana Fernie), and jack pine budworm ( Choristoneura pinus Freeman). Using scanning electron images of scales, we made qualitative and quantitative comparisons of morphological traits at the ultrastructural level. We found that hemlock looper and eastern blackheaded budworm scales could be categorically separated from each other and from the three other species. We developed a quadratic discriminant function using measurements of ultrastructure traits that distinguishes scales of the three remaining species with an overall accuracy of 66%. We found that forest tent caterpillar could be well separated based on these traits, but we were less confident in distinguishing the closely related jack pine and spruce budworm. Our method offers potential advantages in scale identification for future studies in paleoecology, while providing the additional advantage of not requiring intact, unfolded, and undamaged scales.

Changes in Nesting Density of Baltimore Orioles (1976-1995) and Other Species in the Dune- Ridge Forest, Delta Marsh, MB: Response to an Outbreak of Forest Tent Caterpillar?

Changes in Nesting Density of Baltimore Orioles (1976-1995) and Other Species in the Dune- Ridge Forest, Delta Marsh, MB: Response to an Outbreak of Forest Tent Caterpillar?