Vegetation-environment relationships are well understood for boreal lichen woodlands, but the mechanistic basis for small-scale understory patchiness (patches dominated by lichen, mosses, and vascular plants), and its implications for the prevalence of niche vs. neutral processes driving understory development, have not been explored. We asked whether predictable vegetation-environment associations exist at the microsite scale, with the goal of informing caribou range management. We sampled canopy and edaphic variables in patches of lichen, feathermoss, and vascular plants in subalpine lodgepole pine (Pinus contorta var. latifolia Engelm. ex S.Wats.) forests, in north-central British Columbia, Canada. Lichens positively associate with microsites that have high light and heat, and low moisture and nutrient availability; vascular plants positively associate with base-cation availability, sulphur and phosphorus availability, fine-textured soils, thick organic layers, and high light; feathermosses positively associate with low light and heat, and nitrogen availability. Understory composition is most strongly associated with canopy characteristics, but is also related to edaphic properties in predictable ways; soil and canopy attributes may further interact to define distinct intra-stand niches. The viability of caribou winter ranges can likely be extended by partially thinning or burning the canopy and organic layers, but the longevity of a lichen-dominant stage may ultimately depend on the soil texture, due to its influence on vascular plant growth.Résumé : Les relations végétation-environnement des forêts boréales à lichens sont bien connues, mais la base mécanistique de la microrépartition du sous-étage à petite échelle (taches dominées par les lichens, les mousses et les plantes vasculaires), et ses implications dans la prévalence de la niche vs. les processus neutres qui contrôlent le développement du sous-étage, n'ont pas été explorées. Les auteurs ont demandé si des associations végétation-environnement prévisibles existent à l'échelle du microsite, afin de mieux gérer les grands pâturages de caribous. Ils ont échantillonné le couvert forestier et les variables édaphiques dans les taches de lichens, d'Hylocomiaceae et de plantes vasculaires dans des forêts de pins lodgepole subalpines (Pinus contorta var. latifolia Engelm. ex S.Wats.), dans le centre-nord de la Colombie-Britannique, Canada. Les lichens étaient associés positivement aux microsites bénéficiant de lumière et de chaleur élevées, et d'une humidité et d'une disponibilité en nutriments faibles ; les plantes vasculaires étaient associés positivement à la disponibilité en cations basiques, à la disponibilité en soufre et phosphore, aux sols de texture fine, aux couches organiques épaisses et à une lumière élevée, les Hylocomiaceae étaient associées positivement à une lumière et une chaleur faibles, et à la disponibilité en azote. La composition du sous-étage était plus fortement associée aux caractéristiques du couvert forestier, mais elle était aussi ...

Projections for forest disturbance and damage under a changing climate in British Columbia are summarized, with the objective of collating regionally specific expectations so that land managers can take pro-active steps to avoid or adapt to the changes expected.  While some projections are based on extrapolations of recent multi-decadal trends, most are based on global climate models (GCMs) that must make assumptions about the range of CO2 emissions and the status of atmospheric greenhouse gas emissions over the next century. Regardless of emission scenarios, it is universally expected that British Columbia will experience warmer air temperatures, coupled with more precipitation in some regions and less in others. Forest fires are expected to be more frequent and more intense in the southern half of the province and in the Taiga Plains, but less important in other portions of the province.  Forest insects and fungal pathogens are expected to more fully occupy the current range of their host tree species and expand ranges northward and to higher elevations along with their hosts.  More frequent and detrimental pest outbreaks are expected in some regions when several years of favourable weather align.  Wind damage, floods, and landslides can be expected to increase on terrain where they are already a risk factor.  For many agents of tree mortality, expected changes in disturbance regime amount to an expansion or shifting of the seasonal window of activity, sometimes with different trends projected for different seasons and different regions of the province.  The prediction of future forest disturbance regimes is in its infancy, requiring a much more concerted effort in compiling both empirical and simulated data, but managers may wish to adjust plans accordingly where there is largely a consensus among current and projected trends.

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Six intensively managed white spruce (Picea glauca (Moench) Voss) plantations located in three general landscape contexts (plantation dominated, hardwood dominated, and mixed hardwood and plantation) in northern New Brunswick underwent alternative commercial thinning (CT) treatments: 1) an unthinned control; and three 40% basal area CT removals, with 2) slash and tops remaining on site (status quo CT), 3) branches and tops extracted from the site (biomass removal CT), and 4) clumps of unthinned trees left, and one-half girdled to create snags (enhanced structure CT). We examined responses of taxa that have a clear connection to deadwood and thinning response: beetles and bird species that are directly dependent upon deadwood, ground vegetation species sensitive to disturbance, and small mammals that have been observed to have low density in planted stands. Results three years post-thinning showed that crown width and tree growth responded positively to CT, and herbaceous vegetation diverged from reference stands and unthinned treatments with CT, but greatest compositional change was associated with biomass removal CT. Beetles responded positively to CT, small mammal species responded both positively (red-backed voles) and negatively (woodland jumping mice) to CT, but areas dominated by plantations had negative effects on voles. Effects of CT on songbirds were unclear and their quantification would require larger treated blocks, but maintenance of habitat at the landscape level is essential for the conservation of bird species that require deadwood. The experimental biomass removal CT was least similar to both unthinned and older unmanaged stands, and may therefore be detrimental to biodiversity conservation efforts. These results are only the initial three years after treatment but set the study up to permit a long-term legacy of determining long-term responses of taxa over stand development.Keywords: commercial thinning, beetles, songbirds, small mammals, ground vegetation, deadwood, tree growth response, plantation habitat RÉSUMÉ Six plantations d' épinette blanche (Picea glauca (Moench) Voss) aménagées de façon intensive, et situées dans trois paysages forestiers différents (prédominance de plantation, prédominance de feuillus et mélange de feuillus et de plantation) dans le nord du Nouveau-Brunswick ont fait l' objet de traitements d' éclaircie alternatifs (ÉC) : 1) témoin non éclairci; et trois éclaircies commerciales à 40 % de la surface terrière avec 2) abandon des branches et des houppiers sur le parterre de coupe (ÉC statu quo), 3) enlèvement des branches et des houppiers de sur le parterre de coupe (ÉC avec prélèvement de la biomasse), et 4) maintien de groupes d'arbres non éclaircis et annelés à moitié pour créer des chicots (ÉC avec structure améliorée). Nous avons étudié les taxons qui ont un lien étroit avec le bois mort ainsi que leur réaction à l' éclaircie : les coléoptères et les oiseaux qui ont absolument besoin de bois mort, les espèces vivant dans la végétation du sol, sensibles aux ...