No abstract

Live tree diameter distributions, and abundance and quality of standing and downed coarse woody debris (CWD), were compared among three northern hardwood stand types in the Adirondack Mountains of New York, USA: old growth; partially cut, unevenaged with 40-50 cm maximum residual diameters; and maturing, even-aged, 90-100 yr old, postfire. Downed CWD (stumps Յ1 m tall and logs) volumes in the old-growth, partially cut, and maturing stands were 139, 69, and 61 m 3 /ha, respectively. Large (Ն50 cm diameter) CWD comprised 17%, 13%, and 4% of the total downed CWD volume in the old-growth, partially cut, and maturing stands respectively. Approximately one-half the large CWD in the partially cut stands was in the form of cut stumps. Standing CWD (stumps Ͼ1 m tall and standing dead trees) basal areas averaged 8.6, 1.2, and 4.1 m 2 /ha in the old-growth, partially cut, and maturing stands, respectively. Basal area of large (Ն50 cm diameter) standing CWD averaged 70%, 0%, and 5% of the total in the old-growth, partially cut, and maturing stands. Both downed and standing CWD loads were influenced by mortality due to beech bark disease. Decay distributions of downed CWD were similar in all stand types. The old-growth stands averaged 55 live trees Ն50 cm dbh/ha, including 14 trees Ն70 cm dbh/ha. The partially cut stands contained 5 trees Ն50 cm dbh/ha, with none Ͼ55 cm dbh. The maturing, even-aged, stands averaged 1.3 stems Ն50 cm dbh/ha in the postdisturbance cohort but also had ϳ8 postfire residuals/ha with diameters up to 70 cm dbh.Implementing forest ecosystem management guidelines to emulate the structural characteristics of old-growth northern hardwoods should retain at least 16 live trees/ha Ն50 cm dbh including 6 trees/ha Ն70 cm dbh. Target levels for downed CWD volume would be less (perhaps 25% less) than the 139 m 3 /ha reported here, considering the influence of beech bark disease on the stands we studied. These goals can be accomplished by increasing diameter limits in selection systems, by extending even-aged rotations beyond 100 yr, and implementing ''reserve shelterwood'' cuts that retain large trees in regenerated, even-aged stands. Retaining large trees will provide more future options to increase the proportion of large standing and downed CWD in managed stands.

Live tree diameter distributions, and abundance and quality of standing and downed coarse woody debris (CWD), were compared among three northern hardwood stand types in the Adirondack Mountains of New York, USA: old growth; partially cut, unevenaged with 40-50 cm maximum residual diameters; and maturing, even-aged, 90-100 yr old, postfire. Downed CWD (stumps Յ1 m tall and logs) volumes in the old-growth, partially cut, and maturing stands were 139, 69, and 61 m 3 /ha, respectively. Large (Ն50 cm diameter) CWD comprised 17%, 13%, and 4% of the total downed CWD volume in the old-growth, partially cut, and maturing stands respectively. Approximately one-half the large CWD in the partially cut stands was in the form of cut stumps. Standing CWD (stumps Ͼ1 m tall and standing dead trees) basal areas averaged 8.6, 1.2, and 4.1 m 2 /ha in the old-growth, partially cut, and maturing stands, respectively. Basal area of large (Ն50 cm diameter) standing CWD averaged 70%, 0%, and 5% of the total in the old-growth, partially cut, and maturing stands. Both downed and standing CWD loads were influenced by mortality due to beech bark disease. Decay distributions of downed CWD were similar in all stand types. The old-growth stands averaged 55 live trees Ն50 cm dbh/ha, including 14 trees Ն70 cm dbh/ha. The partially cut stands contained 5 trees Ն50 cm dbh/ha, with none Ͼ55 cm dbh. The maturing, even-aged, stands averaged 1.3 stems Ն50 cm dbh/ha in the postdisturbance cohort but also had ϳ8 postfire residuals/ha with diameters up to 70 cm dbh.Implementing forest ecosystem management guidelines to emulate the structural characteristics of old-growth northern hardwoods should retain at least 16 live trees/ha Ն50 cm dbh including 6 trees/ha Ն70 cm dbh. Target levels for downed CWD volume would be less (perhaps 25% less) than the 139 m 3 /ha reported here, considering the influence of beech bark disease on the stands we studied. These goals can be accomplished by increasing diameter limits in selection systems, by extending even-aged rotations beyond 100 yr, and implementing ''reserve shelterwood'' cuts that retain large trees in regenerated, even-aged stands. Retaining large trees will provide more future options to increase the proportion of large standing and downed CWD in managed stands.

Two frequently used measures of relative stand density, the tree area ratio and the stand density index, were fitted to data from Allegheny hardwood stands. Both were modified to reflect the influence of species composition, since the proportion of the basal area in different species groups had an important effect on the measurement of relative stand density in this mixed species forest type. The tree area ratio model provided a better fit to the data than the stand density index model, particularly when adapted to include three species groups: one based on Prunusserotina Ehrh. and Liriodendrontulipifera L., one based on Acerrubrum L., and one based on Acersaccharum Marsh, and Fagusgrandifolia Ehrh.

No abstract

Rubus often becomes the most prominent vegetation within 2–3 years following heavy overstory disturbances at mesic sites within temperate forests of northeastern North America. This review draws together available literature about its dynamics and effects, focusing primarilyon raspberry (Rubus idaeus L.) and blackberry (Rubus allegheniensis Porter). It covers some key ecologic functions of raspberries related to nutrient leaching, microclimate near the ground, and organic matter decomposition. It also summarizes published information about the potentialinterference with desirable tree regeneration at northern hardwood sites within the region. The review concentrates on raspberry (Rubus spp.) dynamics and effects following clearcutting, shelterwood method, and other heavy overstory disturbances. Findings indicate that raspberries commonlydevelop into a dense cover after cutting and other overstory disturbances reduce the stocking of northern hardwood stands by 40% or more. Ecologically, they shade the ground, intercept and transpire water, and reduce the rate of litter decomposition and nutrient cycling, all of whichreduce leaching from a site. On poorly drained, droughty, and shallow soils, raspberries have reportedly delayed the development of hardwood regeneration. However, by 5–7 years, rapidly developing hardwood species have normally grown through the Rubus at most other sites, andthe emerging tree community has formed a closed canopy by 10–15 years. The presence of abundant, well-developed, and well-distributed advance tree regeneration ensures prompt restocking of new hardwoods, seems to minimize the potential for interference by raspberries, and precludes anyneed to release the tree seedlings from a raspberry cover. North. J. Appl. For. 23(4):288 –296.

No abstract

At three previously thinned, even-aged northern hardwood stands affected by the 1998 ice storm, we evaluated the responses of trees in plots given a rehabilitation treatment, and compared findings to adjacent untreated areas. In both the rehabilitated and untreated areas mortality seemed consistent with regional norms for northern hardwood stands. Trees that died after the storm had essentially complete crown loss due to ice loading, and 12% of living trees lost at least half of their crown. In both sets of plots, epicormic branching within the crown led to crown rebuilding, resulting in high levels of tree survival and good post-storm diameter growth on all plots. Release of selected upper-canopy trees by the rehabilitation cutting significantly increased diameter growth rates compared to those in untreated areas. While some epicormics developed below the base of the original crown in both treated and untreated plots, they largely emanated at > 5.2 m from the ground and did not degrade the butt log of most trees.Keywords: ice storm, even-aged northern hardwoods, rehabilitation treatment, stand growth, stand mortality, epicormic branching. RéSuméAu moyen de mesures effectuées dans des parcelles, nous avons évalué la réaction des arbres à la suite du verglas de 1998 dans trois peuplements équiennes de feuillus nordiques éclaircis qui avaient bénéficié d'un traitement de réhabilitation, et comparé les résultats à ceux des parcelles voisines n'ayant reçu aucun traitement. Tant dans les parcelles réhabilitées que dans celles non traitées, la mortalité semblait conforme aux standards régionaux pour les peuplements de feuillus nordiques. Les arbres qui sont morts après la tempête de verglas avaient essentiellement perdu l' ensemble de leur cime sous le poids de la glace et 12 % des arbres vivants avaient perdu au moins la moitié de leur cime. Dans les deux groupes de parcelles, la croissance des pousses adventives dans la cime a permis à celle-ci de se rétablir ce qui a donné un fort niveau de survie chez les arbres et une bonne croissance en diamètre post-tempête dans toutes les parcelles. Le dégage-ment des arbres choisis parmi les dominants au cours de la coupe de réhabilitation a considérablement augmenté les taux de croissance en diamètre, comparativement aux arbres des parcelles non traitées. Même si certaines pousses adventives se sont développées sous le niveau de la cime originale, tant dans les parcelles traitées que dans celles non traitées, elles se trouvaient en grande partie à plus de 5,2 m au-dessus du sol et n' ont pas déclassé la bille de souche de la plupart des arbres.