Considerable controversy has arisen over the management of white‐tailed deer in eastern landscapes where there is evidence of damage to forest vegetation, crops, and wildlife habitat attributable to deer. We examined the impact of 4, 8, 15, and 25 deer/km2 on herbaceous layer abundance and tree seedling density, height development, species composition, and diversity for 10 yr in a repeated‐measures randomized‐complete‐block experiment at four replicate cherry–maple forest sites in northwestern Pennsylvania, USA. At each 65‐ha site, deer were placed in 13‐ or 26‐ha fenced enclosures in which the landscape composition and forage production of a forest managed on a 100‐yr rotation was simulated by clear‐cutting 10% of each area and thinning 30%. Vegetation was sampled 0–1, 3, 5, and 10 yr after treatment (YAT). We analyzed vegetative treatment responses separately in each silvicultural treatment. Time was an important factor mediating responses at all deer densities. Rubus spp. abundance in all silvicultural treatments and the density of striped maple (STM) in clearcuts and birch (BI), American beech (AB), and red maple (RM) in thinnings showed negative trends with increasing deer density. As deer density increased, we found negative linear trends in the height of BI, RM, and AB in clearcuts; in the height of AB, RM, and STM in thinnings; and in the height of AB and RM in uncut stands. Species richness showed a negative linear trend with increasing deer density in all silvicultural treatments. Conversely, species avoided by deer or resilient to deer browsing increased with increasing deer density. Percent cover of ferns, grasses, and sedges showed positive linear trends with deer density in clearcuts and in thinnings. The percentage of plots dominated by black cherry (BC) increased with increasing deer density in cut and uncut stands. The net result of increased deer impact was an altered trajectory of vegetation development dominated by species avoided by deer or resilient to deer browsing. Negative effects on vegetation became significant at deer impact levels well below those observed in many eastern forests. Moreover, species not browsed or resilient to browsing may have indirect effects on vegetation development through plant–plant interactions and on wildlife habitat quality for small mammals, birds, and deer. Managing these impacts is important as pressures to harvest and fragment eastern forests accelerate. Corresponding Editor: R. S. Ostfeld.

Mortality of sugar maple (Acer saccharum Marsh.) has reached unusually high levels across northern Pennsylvania since the early to mid-1980s. We evaluated the influence of glaciation, topographic position, foliage chemistry, defoliation history, and stand characteristics (species composition, structure, density) on the health of sugar maple in 43 stands at 19 sites on the northern Allegheny Plateau. Using percent dead sugar maple basal area as the measure of health, we found that all moderately to severely declining stands were on unglaciated summits, shoulders, or upper backslopes. Stands on glaciated sites and unglaciated lower topographic positions were not declining. The most important factors associated with sugar maple health were foliar levels of Mg and Mn and defoliation history. The lowest foliar Mg, highest foliar Mn, and highest number and severity of insect defoliations were associated with unglaciated summits, shoulders, and upper backslopes. Declining stands had less than -700 mg·kg -1 Mg and two or more moderate to severe defoliations in the past 10 years; both conditions were associated with moderately to severely declining stands. The decline disease of sugar maple seems to result from an interaction between Mg (and perhaps Mn) nutrition and stress caused by defoliation.Résumé : La mortalité de l'érable à sucre (Acer saccharum Marsh.) a atteint des proportions anormalement élevées partout dans le nord de la Pennsylvanie depuis le début ou le milieu des années 1980. Nous avons étudié l'influence de la glaciation, de la topographie, de la chimie foliaire, des défoliations passées, et des caractéristiques du peuplement (composition, structure et densité) sur la santé de l'érable à sucre dans 43 peuplements établis sur 19 sites dans la partie nord du plateau alléghanien. En utilisant le pourcentage de surface terrière que représentent les érables à sucre morts comme mesure de l'état de santé, nous avons trouvé que tous les peuplements où le dépérissement était modéré à sévère étaient situés sur les sommets, les contreforts, ou le haut des revers qui n'avaient pas subi la glaciation. Les peuplements situés sur des sites exposés à la glaciation ou des sites plus bas qui n'avaient pas subi la glaciation ne dépérissaient pas. Les facteurs les plus importants associés à la santé de l'érable à sucre étaient les concentrations foliaires de Mg et Mn et les défoliations passées. La plus faible concentration foliaire de Mg, la plus forte concentration foliaire de Mn, la sévérité la plus élevée et le plus grand nombre de défoliations d'insectes étaient associés aux sommets, aux contreforts, ou au haut des revers qui n'avaient pas subi la glaciation. Les peuplements dépérissants avaient moins d'environ 700 mg·kg -1 de Mg et avaient subi au moins deux défoliations modérées à sévères au cours des 10 dernières années. Ces deux facteurs étaient associés à des peuplements où le dépérissement était modéré à sévère. Le dépérissement de l'érable à sucre semble être le résultat d'une interaction entre la nutri...

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atmospheric acid deposition is supported on theoretical grounds (Reuss, 1983), by laboratory experiments (Law-Numerous studies have investigated the potential depletion of rence et al., 1999), by observational mass balance studies available base cation pools from forest soils in regions impacted by acid deposition. However, these studies mostly used indirect methods.

Deer browsing and interference from forest weeds, particularly hayscented fern (Dennstaedtiapunctilobula (Michx.) Moore), New York fern (Thelypterisnoveboracensis L.), and short husk grass (Brachyelytrumerectum Schreb.), influence the establishment of Allegheny hardwood reproduction. We determined the independent interference by deer and weeds after a seed cut and a removal cut in a two-cut shelterwood sequence. Weeds, particularly the ferns, caused significant interference with germination, survival, and growth of desirable species following both cuttings. Deer browsing had no direct effect on desirable species because they did not grow enough to emerge from the herbaceous cover. Deer browsing did affect growth ofRubus, yellow and black birch (Betulaalleghaniensis Britt, and Betulalento L.), and pin cherry (Prunuspensylvanica L.) that grew above the herbaceous cover. Browsing of Rubus may be a serious problem in some stands because substantial reduction in fern and grass coverage occurred as the Rubus developed.

Sugar maple, Acer saccharum, decline disease is incited by multiple disturbance factors when imbalanced calcium (Ca), magnesium (Mg), and manganese (Mn) act as predisposing stressors. Our objective in this study was to determine whether factors affecting sugar maple health also affect growth as estimated by basal area increment (BAI). We used 76 northern hardwood stands in northern Pennsylvania, New York, Vermont, and New Hampshire, USA, and found that sugar maple growth was positively related to foliar concentrations of Ca and Mg and stand level estimates of sugar maple crown health during a high stress period from 1987 to 1996. Foliar nutrient threshold values for Ca, Mg, and Mn were used to analyze long-term BAI trends from 1937 to 1996. Significant (P < or = 0.05) nutrient threshold-by-time interactions indicate changing growth in relation to nutrition during this period. Healthy sugar maples sampled in the 1990s had decreased growth in the 1970s, 10-20 years in advance of the 1980s and 1990s decline episode in Pennsylvania. Even apparently healthy stands that had no defoliation, but had below-threshold amounts of Ca or Mg and above-threshold Mn (from foliage samples taken in the mid 1990s), had decreasing growth by the 1970s. Co-occurring black cherry, Prunus serotina, in a subset of the Pennsylvania and New York stands, showed opposite growth responses with greater growth in stands with below-threshold Ca and Mg compared with above-threshold stands. Sugar maple growing on sites with the highest concentrations of foliar Ca and Mg show a general increase in growth from 1937 to 1996 while other stands with lower Ca and Mg concentrations show a stable or decreasing growth trend. We conclude that acid deposition induced changes in soil nutrient status that crossed a threshold necessary to sustain sugar maple growth during the 1970s on some sites. While nutrition of these elements has not been considered in forest management decisions, our research shows species specific responses to Ca and Mg that may reduce health and growth of sugar maple or change species composition, if not addressed.

Sugar maple (Acer saccharum Marsh.) has been declining across the unglaciated Allegheny Plateau in northwestern and north central Pennsylvania since the mid-1980s. A long-term study to evaluate the effects of fencing, herbicide, and liming on growth, crown vigor, and regeneration of sugar maple and associated Allegheny hardwoods was initiated in 1985.The study is a split-plot design with fencing (fence -no fence) as the whole-plot treatment and four subplot treatments: applications of herbicide (glyphosate) to control interfering vegetation, dolomitic lime (22.4 Mg⋅ha -1 ) to reduce soil acidity, dolomitic lime and herbicide, and an untreated control. Liming significantly increased diameter growth and improved crown vigor of overstory sugar maple, but did not affect growth or vigor of overstory black cherry (Prunus serotina Ehrh.) and American beech (Fagus grandifolia Ehrh.). Basal area (adjusted by covariance) of sugar maple on limed plots increased by 11% from 1986 to 1993 but only by 4% on unlimed plots. Liming increased exchangeable cations in the upper 15 cm of the soil, especially Ca and Mg, and reduced levels of exchangeable K, Al, and Mn. Changes in soil chemistry were reflected in the chemistry of overstory sugar maple foliage. Concentrations of Ca doubled on limed plots and Mg increased fourfold on limed versus unlimed plots. Liming also increased the size (in 1989 and 1992) but not the frequency of sugar maple flower and seed crops. The results demonstrate the importance of Ca and Mg nutrition in maintaining the health of sugar maple on unglaciated sites.Résumé : Depuis le milieu des années 1980, l'érable à sucre (Acer saccharum Marsh.) a souffert de dépérissement sur le plateau Allegheny non soumis à la glaciation dans le nord-ouest et centre-nord de la Pennsylvanie. En 1985, une étude à long terme a été initiée afin d'évaluer les effets de protection par une clôture, d'un herbicide et du chaulage sur la croissance, la vigueur de la cime et la régénération de l'érable à sucre et des espèces feuillues compagnes. Un dispositif en tiroir avec la protection par une clôture (clôture -sans clôture) comme traitement en parcelle principale et quatre traitements en sous-parcelles : l'application d'herbicide (glyphosate) pour contrôler la végétation compétitive, de chaux dolomitique (22,4 Mg⋅ha -1 ) afin de réduire l'acidité du sol, de chaux dolomitique et d'herbicide, et un témoin non traité. Le chaulage a significativement augmenté la croissance en diamètre et amélioré la vigueur de la cime des érables à sucre de l'étage dominant, mais n'a pas affecté la croissance ou la vigueur du cerisier tardif (Prunus serotina Ehrh.) et du hêtre d'Amérique (Fagus grandifolia Ehrh.

Includes guidelines for using the SILVAH decision-support system to perpetuate oak forests in the Mid-Atlantic region. Six chapters provide information on values of oak forests, inventory methods, key decision variables, decision charts, and silvicultural prescriptions, as well as guidance on fostering young stands.