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Forest management techniques such as intermediate stand-tending practices (e.g., thinning) can promote climatic resiliency in forest stands by moderating tree competition. Residual trees gain increased access to environmental resources (i.e., soil moisture, light), which in turn has the potential to buffer trees from stressful climatic conditions. The influences of climate (temperature and precipitation) and forest management (thinning method and intensity) on the productivity of red pine (Pinus resinosa Ait.) in Michigan were examined to assess whether repeated thinning treatments were able to increase climatic resiliency (i.e., maintaining productivity and reduced sensitivity to climatic stress). The cumulative productivity of each thinning treatment was determined, and it was found that thinning from below to a residual basal area of 14 m 2 ·ha −1 produced the largest average tree size but also the second lowest overall biomass per acre. On the other hand, the uncut control and the thinning from above to a residual basal area of 28 m 2 ·ha −1 produced the smallest average tree size but also the greatest overall biomass per acre. Dendrochronological methods were used to quantify sensitivity of annual radial growth to monthly and seasonal climatic factors for each thinning treatment type. Climatic sensitivity was influenced by thinning method (i.e., thinning from below decreased sensitivity to climatic stress more than thinning from above) and by thinning intensity (i.e., more intense thinning led to a lower climatic sensitivity). Overall, thinning from below to a residual basal area of 21 m 2 ·ha −1 represented a potentially beneficial compromise to maximize tree size, biomass per acre, and reduced sensitivity to climatic stress, and, thus, the highest level of climatic resilience. Résumé :Les techniques d'aménagement forestier, telles que les pratiques d'éducation des peuplements au stade intermédiaire (p.ex. l'éclaircie), peuvent faciliter la résilience climatique des peuplements forestiers en atténuant la compétition entre les arbres. Les arbres résiduels ont un meilleur accès aux ressources environnementales (c.-à -d. l'eau du sol et la lumière), ce qui peut les protéger des stress climatiques. L'influence du climat (température et précipitation) et de l'aménagement forestier (méthode et intensité d'éclaircie) sur la productivité du pin rouge (Pinus resinosa Ait.) au Michigan a été étudiée pour évaluer si des traitements répétés d'éclaircie étaient en mesure d'augmenter la résilience climatique (c.-à -d. maintenir la productivité et réduire la sensibilité aux stress climatiques). À partir de la productivité cumulée qui a été déterminée pour chaque traitement d'éclaircie, nous avons trouvé que l'éclaircie par le bas laissant une surface terrière résiduelle de 14 m 2 ·ha −1 était associée à la plus forte taille moyenne des arbres, mais aussi à la deuxième plus faible biomasse totale à l'hectare. D'un autre côté, le témoin non coupé et l'éclaircie par le haut laissant une surface terrière résiduelle de 28 m 2 ...

The forests in northern Michigan will be affected directly and indirectly by changing climate during the 21st century. This assessment evaluates the vulnerability of forest ecosystems in the eastern Upper Peninsula and northern Lower Peninsula of Michigan under a range of future climates. We synthesized and summarized information on the contemporary landscape, provided information on past climate trends, and described a range of projected future climates. This information was used to parameterize and run multiple vegetation impact models, which provided a range of potential vegetative responses to climate. Finally, we brought these results before a multidisciplinary panel of scientists and land managers familiar with Michigan forests to assess ecosystem vulnerability through a formal consensus-based expert elicitation process. The summary of the contemporary landscape identifies major forest trends and stressors currently threatening forests in the region. Observed trends in climate over the past century reveal that precipitation increased in the area, particularly in summer and fall, and that daily maximum temperatures increased, particularly in winter. Projected climate trends for the next 100 years using downscaled global climate model data indicate a potential increase in mean annual temperature of 2.2 to 8.1 °F for the assessment area. Projections for precipitation indicate an increase in winter and spring precipitation, and summer and fall precipitation projections vary by scenario. We identified potential impacts on forests by incorporating these climate projections into three forest impact models (Tree Atlas, LANDIS-II, and PnET-CN). Model projections suggest that northern boreal species such as black spruce and paper birch may fare worse under future conditions, but other species such as American elm and white oak may benefit from projected changes in climate. Published literature on climate impacts related to wildfire, invasive species, and diseases also contributed to the overall determination of climate change vulnerability. We assessed vulnerability for nine forest communities in the assessment area, which were a combination of U.S. Department of Agriculture, Forest Service Forest Inventory and Analysis program forest types and Michigan Natural Features Inventory natural communities. The basic assessment was conducted through a formal elicitation process of 27 science and management experts from across the state, who considered vulnerability both in terms of potential impacts on a system and in terms of the system's adaptive capacity. Upland spruce-fir, jack pine, lowland conifers, and red pine-white pine forest communities were determined to be the most vulnerable. Barrens and lowland/riparian hardwood communities were perceived as less vulnerable to projected changes in climate. These projected changes in climate and the associated impacts and vulnerabilities will have important implications for economically valuable timber species, forest-dependent wildlife and plants, recreation, and long-range p...

Aim Thirty white spruce [Picea glauca (Moench) Voss] islands were sampled to study the temporal and spatial pattern of white spruce regeneration at its southern limit of distribution. Location The study was conducted within three mixed‐grass prairies in the Spruce Woods Provincial Park (SWPP) of south‐western Manitoba. Methods White spruce seedlings, saplings and trees were mapped and measured in relation to eight sectors and five zones delimited by four transect lines extending through the centre of each island oriented north to south, west to east, north‐west to south‐east and north‐east to south‐west. Results Temporal patterns of regeneration were negatively correlated with July temperature at the time of establishment and up to 30 years after establishment. Height growth of seedlings and saplings were also negatively correlated with July temperature. Seedlings, saplings and trees were concentrated on the north vs. south aspect and within 4–12 m from the island centre. Seedlings grew almost exclusively in association with creeping juniper (Juniperus horizontalis Moench). Main conclusions Results of the study suggest that white spruce recruitment and growth reflect past climatic variation, and microclimatic and microsite conditions promoting soil moisture retention and/or fire risk reduction facilitate white spruce germination and establishment.

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This study tests the hypothesis that ring growth in the upper stem portion of trees is affected by climatic conditions differently than rings formed at breast height (1.3 m). A total of 389 trees from a network of 65 lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) sites in Alberta were examined using detailed stem analysis in order to examine interannual patterns of basal area increment and volume increment at different positions along the stem. Growth at lower sections of the bole was mainly driven by temperature and moisture conditions in the seasons prior to the growing season in the year of ring formation, while upper stem growth was more related to conditions during the year of growth, i.e., temperature in the early summer, or moisture in late winter to early spring. This translates into increased allocation of wood to the lower stem when prior late summer conditions are cool and wet, prior winters are mild (warm with little snow) and early summer conditions in the year of ring formation are hot and dry.