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A warming climate and extended growing season may confer competitive advantages to temperate conifers that can photosynthesize across seasons. Whether this potential translates into increased growth is unclear, as is whether pollution could constrain growth. We examined two temperate conifers--eastern white pine (Pinus strobus L.) and eastern hemlock (Tsuga canadensis (L.) Carriere)--and analyzed associations between growth (476 trees in 23 plots) and numerous factors, including climate and pollutant deposition variables. Both species exhibited increasing growth over time and eastern white pine showed greater maximum growth. Higher spring temperatures were associated with greater growth for both species, as were higher autumnal temperatures for eastern hemlock. Negative correlations were observed with previous year (eastern hemlock) and current year (eastern white pine) summer temperatures. Spring and summer moisture availability were positively correlated with growth for eastern white pine throughout its chronology, whereas for hemlock, correlations with moisture shifted from being significant with current year's growth to previous year's growth over time. The growth of these temperate conifers might benefit from higher spring (both species) and fall (eastern hemlock) temperatures, though this could be offset by reductions in growth associated with hotter, drier summers. Key words: dendrochronology, temperate conifers, temperature, moisture, climate change. Un climat plus chaud et une saison de croissance plus longue pourrait conferer des avantages competitifs aux coniferes de la zone temperee chez qui la photosynthese peut se poursuivre en toute saison. Il n'est pas clair si cette possibilite pourrait se traduire par une croissance accrue et de meme si la pollution pourrait limiter la croissance. Nous avons etudie deux coniferes de la zone temperee: le pin blanc (Pinus strobus L.) et la pruche du Canada (Tsuga canadensis (L.) Carriere), et nous avons analyse les liens entre la croissance (476 arbres dans 23 places echantillons) et plusieurs facteurs, incluant des variables liees au climat et aux retombees de polluants. Les deux especes ont augmente leur croissance avec le temps et le pin blanc a connu la croissance maximum la plus elevee. Les temperatures printanieres elevees etaient associees a une plus forte croissance chez les deux especes, ainsi que les temperatures automnales elevees dans le cas de la pruche du Canada. Des correlations negatives ont ete observees avec les temperatures estivales de l'annee precedente (pruche du Canada) et de l'annee en cours (pin blanc). La disponibilite d'humidite au printemps et a l'ete etait positivement correlee avec la croissance du pin blanc tout au long de sa chronologie, tandis que dans le cas de la pruche du Canada les correlations avec l'humidite allaient avec le temps de significatives avec la croissance de l'annee en cours a celle de l'annee precedente. La croissance de ces coniferes de la zone temperee pourrait beneficier de temperatures plus chaudes au printemps (les deux especes) et a l'automne (pruche du Canada), bien que cela puisse etre compense par des reductions de croissance associees a des etes plus chauds et plus secs. [Traduit par la Redaction] Mots-cles: dendrochronologie, coniferes de la zone temperee, temperature, humidite, changement climatique., Introduction Forest composition and growth may shift as the suitability of habitats for component tree species shifts with climate change (Prasad et al. 2007--ongoing). For species in temperate forest communities [...]

Although Dutch elm disease (DED) is the primary threat to American elm (Ulmus americana L.), we hypothesized that shoot freezing injury may also limit tree productivity and survival in the north. We assessed shoot cold tolerance and field winter injury of American elm bred for DED tolerance planted in Lemington, Vermont. We tested for differences in cold tolerance associated with date, maternal DED tolerance sources, paternal sources from plant hardiness zones 5a, 6a, and 6b (determined using data from 1996 to 2005), and the interactions of these. Cold tolerance was greatest in the winter, followed by fall and then spring. For all dates, cold tolerance never differed between maternal DED tolerance sources. However, in mid-winter, paternal sources from zone 5a (coldest zone) were significantly more cold tolerant than sources from zone 6b (warmest zone), and sources from zone 6a were intermediate. Field freezing injury confirmed that shoots were only marginally cold tolerant relative to ambient temperature lows. Key words: cold hardiness, genetic sources, local adaptation, Ulmus americana, winter injury. Bien que la maladie hollandaise de l'orme (MHO) soit la principale menace pour l'orme d'Amerique (Ulmus americana L.), Nous avons emis l'hypothese que les dommages causes par le gel des pousses pourraient egalement limiter la survie et la productivite des arbres dans le nord. Nous avons evalue la tolerance au froid des pousses et les dommages hivernaux chez des ormes d'Amerique selectionnes pour la tolerance a la MHO et plantes a Lemington, au Vermont. Nous avons teste les differences de tolerance au froid associees a la date, aux sources maternelles tolerantes a la MHO, aux sources paternelles provenant des zones de rusticite des plantes 5a, 6a et 6b (determinees a l'aide de donnees de 1996 a 2005) ainsi que les interactions entre ces facteurs. La tolerance au froid etait la plus elevee en hiver, suivie de l'automne puis du printemps. Peu importe la date, la tolerance au froid ne differait pas entre les sources maternelles tolerantes a la MHO. Cependant, au milieu de l'hiver, les sources paternelles de la zone 5a (zone la plus froide) etaient significativement plus tolerantes au froid que les sources de la zone 6b (zone la plus chaude) et les sources de la zone 6a etaient intermediaires. Les dommages dus au gel sur le terrain ont confirme que les pousses n'etaient que legerement tolerantes au froid par rapport aux minima de temperature ambiante. [Traduit par la Redaction] Mots-cles : resistance au froid, sources genetiques, adaptation locale, Ulmus americana, dommages hivernaux., Introduction American elm (Ulmus americana L.) was once an important component of wetland and floodplain forests from the eastern coast of North America (Florida through Nova Scotia) west to southeastern [...]

Green ash is threatened with extirpation from emerald ash borer (EAB) attack. Because green ash has an extensive range, its restoration could require both breeding for EAB resistance and possible adaptation to a variety of environmental gradients. We assessed the growth and climate sensitivity of green ash from five Plant Hardiness Zones (PHZs) growing in a range-wide provenance test in Vermont. Although there tended to be greater growth among trees from the warmest PHZ (7), differences were rarely statistically distinguishable. For trees from all PHZs, growth was positively correlated with precipitation in the current year and negatively correlated with precipitation the year before (a possible legacy effect). Growth was negatively associated with temperature the year of ring formation but positively associated with temperatures the year before. Growth was often positively correlated with winter snow but was negatively associated with spring or fall snow for the warmest PHZs. Climate correlations for PHZ 3 were unusual in that (1) only positive correlations were detected, (2) no legacy effects were noted, and (3) despite being from the coldest region, no correlations with snow were found. Growth increased over time for the warmest PHZs during a period of simultaneous increases in temperature and precipitation. [ABSTRACT FROM AUTHOR]

Red oak (Quercus rubra L.) is projected to expand into the northern hardwood forest over the coming century. We explored the connection between red oak basal area growth and a number of factors (tree age and size, stand dynamics, site elevation, and climate and acid deposition variables) for 213 trees in 11 plots throughout Vermont, USA. Red oak growth generally increased over the course of the chronology (1935-2014) and has been particularly high in recent decades. Growth differed among elevational groups but did not differ between age or size groups. Summer moisture metrics were consistently and positively associated with growth, whereas fall moisture was associated with reduced growth in recent decades. Higher summer temperatures were often negatively associated with growth, though there was evidence that low temperatures in the summer (higher elevations) and fall (lower elevations) constrain growth. Several pollution metrics were associated with reduced growth, a surprising result for a species not known to be sensitive to inputs of acid deposition that have predisposed other species in the region to decline. While red oak growth is currently robust, increases in summer temperatures, reductions in growing season precipitation, or increases in fall precipitation could reduce future growth potential. Key words: Quercus rubra, dendrochronology, tree rings, climate change, acid deposition. Le chene rouge (Quercus rubra L.) devrait augmenter sa presence dans la zone des forets de feuillus nordiques au cours du prochain siecle. A partir de 213 arbres repartis dans 11 placettes etablies dans l'Etat du Vermont, aux Etats-Unis, nous avons explore les liens entre la croissance en surface terriere du chene rouge et les facteurs suivants: l'age et la taille des arbres, la dynamique des peuplements, l'altitude de la station, et des variables climatiques et de depots acides. La croissance du chene rouge a generalement augmente pendant la periode couverte par la chronologie (1935-2014) et a ete particulierement elevee au cours des dernieres decennies. La croissance etait differente entre les classes d'altitude, mais pas entre les classes d'age ou de taille. Les mesures d'humidite estivale etaient systematiquement et positivement associees a la croissance, tandis que l'humidite automnale etait negativement associee a la croissance au cours des dernieres decennies. Des temperatures estivales elevees etaient souvent associees negativement a la croissance, bien que de basses temperatures estivales (altitudes plus elevees) et automnales (altitudes plus basses) aient aussi limite la croissance. Plusieurs mesures de pollution ont ete associees a une reduction de croissance, ce qui est un resultat surprenant pour une espece qui n'est pas reconnue pour sa sensibilite aux depots acides qui ont, par ailleurs, predispose d'autres especes de la region a un declin. Bien que la croissance du chene rouge soit actuellement robuste, l'augmentation des temperatures estivales, la reduction des precipitations pendant la saison de croissance ou l'augmentation des precipitations automnales pourraient reduire son futur potentiel de croissance. [Traduit par la Redaction] Mots-cles : Quercus rubra, dendrochronologie, anneaux de croissance, changements climatiques, depots acides., Introduction As climate change progresses, efforts are underway to understand how and when forests and constituent tree species will respond. Numerous studies have applied models to estimate the composition and [...]

We evaluated shoot nonstructural carbohydrate (NSC) concentrations, stem wound closure, and radial growth of sugar maple (Acer saccharum Marsh.) and red maple (Acer rubrum L.) trees in a novel ice storm experiment in which five storm treatments (0, 6.4, 12.7, and 19.1 mm of radial ice accretion in 1 year and 12.7 mm of ice in two consecutive years) were applied within a mature northern hardwood forest. We tested for changes in physiology at two levels: (1) associated with plot-level ice treatments and (2) with crown damage classes of individual trees. Few differences in NSC or wound closure associated with treatment were found. Growth decreased for red maple in the medium and high treatments and sugar maple in the high treatment but no other treatments. Changes in physiology were more evident when assessed using crown damage classes. Two NSC components were elevated in sugar and red maples with high (≥50%) crown damage. Wound closure was less for red maples with high damage, and separation among damage classes was even greater for sugar maple. Red maples with moderate (<50%) and high crown damage showed gradually declining growth, whereas sugar maples with high damage showed ∼80% reduction in growth the first year after injury. [ABSTRACT FROM AUTHOR]

Acid deposition induced losses of calcium (Ca) from northeastern forests have had negative effects on forest health for decades, including the mobilization of potentially phytotoxic aluminum (Al) from soils. To evaluate the impact of changes in Ca and Al availability on sugar maple (Acer saccharum Marsh.) and American beech (Fagus grandifolia Ehrh.) growth and forest composition following a major ice storm in 1998, we measured xylem annual increment, foliar cation concentrations, American beech root sprouting, and tree mortality at the Hubbard Brook Experimental Forest (Thornton, New Hampshire) in control plots and in plots amended with Ca or Al (treated plots) beginning in 1995. Dominant sugar maple trees were unaffected by the treatment, but nondominant sugar maple tree growth responded positively to Ca treatment. Although plots were mainly composed of sugar maple, American beech experienced the greatest growth on Al-treated plots. Increases in tree mortality on Al-treated plots may have released surviving American beech and increased their growth. The Al tolerance of American beech and the Ca:Al sensitivity of sugar maple contributed to divergent growth patterns that influenced stand productivity and composition. Given that acidic inputs are expected to continue, the growth dynamics associated with Al treatment may have direct relevance to future conditions in native forests. Key words: acid deposition, dendrochronology, ice storm, tree growth, Hubbard Brook. Les pertes de calcium (Ca) provoquees par les depots acides dans les forets du nord-est ont eu des effets nefastes sur la sante des forets pendant plusieurs decennies, incluant la mobilisation de l'aluminium (Al) dans le sol, un element potentiellement phytotoxique. Pour evaluer l'impact des changements dans la disponibilite de Ca et Al sur la croissance de l'erable a sucre (Acer saccharum Marshall) et du hetre d'Amerique (Fagus grandifolia Ehrh.) ainsi que sur la composition de la foret a la suite d'un verglas important survenu en 1998, nous avons mesure l'accroissement annuel du xyleme, la concentration des cations dans les feuilles, la production de drageons par le hetre d'Amerique et la mortalite des arbres a la foret experimentale de Hubbard Brook (Thornton, New Hampshire) dans des placettes temoins et traitees depuis 1995 par l'apport de Ca ou Al. Le traitement n'a pas eu d'effet sur les erables a sucre dominants mais la croissance des erables a sucre non dominants a reagi positivement a l'apport de Ca. Bien que les placettes aient ete principalement composees d'erable a sucre, le hetre d'Amerique a connu une meilleure croissance dans les placettes traitees avec Al. Une plus forte mortalite des arbres dans les placettes traitees avec Al pourrait avoir degage les hetres d'Amerique qui avaient survecu et favoriser leur croissance. La tolerance du hetre d'Amerique a Al et la sensibilite de l'erable a sucre a Ca:Al ont engendre des patrons de croissance divergents qui influencent la productivite et la composition du peuplement. Comme on s'attend a ce que les depots acides persistent, la dynamique de croissance associee au traitement avec Al represente probablement les conditions futures dans les forets naturelles. [Traduit par la Redaction] Mots-cles : depots acides, dendrochronologie, verglas, croissance des arbres, Hubbard Brook., Introduction Acidification of forests in northeastern North America has been a widespread problem for tree health for decades. Causal factors include high acid loading from anthropogenic sources (Likens and Bormann [...]

Despite considerable study, it remains uncertain what environmental factors contribute to red spruce (Picea rubens Sarg.) foliar winter injury and how much this injury influences tree C stores. We used a long-term record of winter injury in a plantation in New Hampshire and conducted stepwise linear regression analyses with local weather and regional pollution data to determine which parameters helped account for observed injury. Two types of weather phenomena were consistently associated with elevated injury: (i) measures of low-temperature stress that incite injury and (ii) factors that reduced the length of the growing season and predisposed trees to injury. At this plantation, there was a significant linear relationship between winter injury and growth reductions for 2 years after a severe winter injury event. Analysis using data from three New England states indicated that plantation data reflected a regional response. Using regional data, we estimated a reduction of 394 000 metric tons of C sequestered in living red spruce stems ≥20 cm in diameter growing in New York and northern New England during the 2 years following a severe winter injury event. This is a conservative estimate of reduced C sequestration because injury-induced mortality and other factors were not evaluated. Malgre le nombre considerable d'etudes, on ne sait toujours pas avec certitude quels facteurs environnementaux contribuent aux dommages foliaires qui surviennent durant l'hiver chez l'epinette rouge (Picea rubens Sarg.), ni a quel point ces dommages influencent les reservoirs de C dans l'arbre. Nous avons utilise des releves a long terme des dommages qui sont survenus durant l'hiver dans une plantation du New Hampshire et nous avons effectue des analyses de re-gression lineaire pas a pas avec les donnees meteorologiques locales et les donnees regionales de pollution pour determiner quels parametres permettaient d'expliquer les dommages observes. Deux types de phenomene meteorologique etaient invariablement associes a des dommages severes: (i) des mesures de stress du' a de basses temperatures et (ii) des facteurs qui reduisent la duree de la saison de croissance et predisposent les arbres aux dommages. Dans cette plantation, il y avait une relation lineaire significative entre les dommages survenus pendant l'hiver et les reductions de croissance pendant les deux annees suivant un episode de dommages severes dus au froid. L'analyse des donnees provenant de trois E tats de la Nouvelle-Angleterre indiquent que les donnees de la plantation refletent une reponse regionale. A l'aide de donnees regionales, nous avons estime que la sequestration de C dans les tiges d'epinette rouge ≥20 cm de diametre etait reduite de 394 000 tonnes metriques dans l'E tat de New York et le nord de la Nouvelle-Angleterre au cours des annees qui ont suivi un episode de dommages severes dus au froid. Il s'agit d'une estimation conservatrice de la reduction de la sequestration de C parce que la mortalite causee par les dommages dus au froid et les autres facteurs n'a pas ete evaluee. [Journal translation], Introduction Red spruce (Picea rubens Sarg.) winter injury is the reddening and mortality of foliage in late winter following freezing damage (DeHayes 1992). The current-year foliage of red spruce is [...]

The limestone bluff cedar–pine forest is a rare upland natural community that is threatened by development and invasion by exotic species. Furthermore, the sensitivity of this forest-type to changes in climate and pollution exposure is unknown. We collected xylem increment cores from 4 conifer species (Thuja occidentalis [Northern White Cedar], Juniperus virginiana [Eastern Red Cedar], Pinus strobus [Eastern White Pine], and Tsuga canadensis [Eastern Hemlock]) and 4 hardwood species (Quercus rubrum [Northern Red Oak], Quercus alba [White Oak], Fagus grandifolia [American Beech], and Fraxinus americana [White Ash]) within and close to a cedar–pine forest along the eastern shore of Lake Champlain in Vermont and correlated radial tree growth to precipitation, snow, temperature, and pollution data to assess which factors influenced growth during the time period 1937–2016. We examined growth and possible environmental drivers of it for a variety of species to evaluate how unique these may be for the cedar and pine trees emblematic of the limestone-bluff community. For both conifers and hardwoods, precipitation exhibited the strongest positive correlations with growth and occurred with greater frequency compared to other climate and pollution parameters. Snow was positively associated and temperature was negatively associated with growth for all species. Despite growing over calcium-rich bedrock, and especially for the conifers, pollution seemed to limit growth in years prior to pollution reductions enacted following the 1990 Amendments to the Clean Air Act. [ABSTRACT FROM AUTHOR]