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"Forêts anciennes Conservation."
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The power of trees : how ancient forests can save us if we let them
\"From the international bestselling author of The Hidden Life of Trees. An illuminating manifesto on ancient forests: how they adapt to climate change by passing their wisdom through generations, and why our future lies in protecting them. In his beloved book The Hidden Life of Trees, Peter Wohlleben revealed astonishing discoveries about the social networks of trees and how they communicate. Now, in The Power of Trees, he turns to their future, with a searing critique of forestry management, tree planting, and the exploitation of old growth forests. As human-caused climate change devastates the planet, forests play a critical role in keeping it habitable. While politicians and business leaders would have us believe that cutting down forests can be offset by mass tree planting, Wohlleben offers a warning: many tree planting campaigns lead to ecological disaster. Not only are these trees more susceptible to disease, flooding, fires, and landslides, we need to understand that forests are more than simply a collection of trees. Instead, they are ecosystems that consist of thousands of species, from animals to fungi and bacteria. The way to save trees, and ourselves? Step aside and let forests--which are naturally better equipped to face environmental challenges--heal themselves. With the warmth and wonder familiar to readers from his previous books, Wohlleben also shares emerging scientific research about how forests shape climates both locally and across continents; that trees adapt to changing environmental conditions through passing knowledge down to their offspring; and how old growth may in fact have the most survival strategies for climate change. At the heart of The Power of Trees lies Wohlleben's passionate plea: that our survival is dependent on trusting ancient forests, and allowing them to thrive.\"-- Provided by publisher.
Book
Defining deer overabundance and threats to forest communities: From individual plants to landscape structure
Changes in habitat and reduction in predation and hunting pressure are two primary causes of high-density populations of white-tailed deer (Odocoileus virginianus) in many areas of eastern North America. Despite increasing recognition of the major effects deer exert on forest communities, deciding when deer are overabundant remains a major challenge to managers charged with conserving native plant communities. In this context, we define overabundance as a condition where deer are causing the local extinction of a native plant species. Because this definition is difficult to apply from a management perspective, we outline an approach using native understory forbs. Indicator species are selected based on combined criteria of palatability to deer, leaf and flower morphology, and demographic characteristics. Four indices related to plant population viability are derived from understory survey data: flowering rate, mean stem height, stage-class distribution, and deer browsing pressure. We apply this analysis to Trillium populations from forests in Minnesota (highly fragmented agricultural landscape with varying deer densities), Pennsylvania (forested and fragmented landscape with long-term high deer densities), and New York (forested and fragmented landscape with long-term low deer densities). We observed two distinct types of deer-affected plant populations. In sites with moderate or recent increases in deer density, Trillium populations were characterized by low mean plant size, high browsing rates, intermediate flowering rates, and a size class distribution lacking large, reproductive plants. Sites affected by long-term high deer densities exhibited low browsing rates on Trillium, low Trillium flowering rates, a population structure lacking both large and small plants, and high summer browsing pressure on woody saplings. We suggest these combined indices be used to assess deer browsing impact, and we discuss the role of landscape structure and deer density in defining deer overabundance.
Journal Article
Germination Requirements and Seed Mass of Slow- and Fast-Colonizing Temperate Forest Herbs Along a Latitudinal Gradient
Predictions on displacement of suitable habitats due to climate change suggest that plant species with poor colonization ability may be unable to move fast enough to match forecasted climate-induced changes in habitat distribution. However, studies on early Holocene plant migration show fast migration of many plant species that are poor colonizers today. We hypothesize that warmer temperatures during the early Holocene yielded higher seed quality, contributing to explaining the fast migration. We studied how the 3 seed quality variables, seed mass, germinability, and requirements for break of seed dormancy, vary for seeds of 11 forest herb species with varying colonization capacity collected along a 1400-km latitudinal gradient. Within species, seed mass showed a positive correlation with latitude, whereas germinability was more positively correlated with temperature (growing degree hours obtained at time of seed collection). Only slow-colonizing species increased germinability with temperature, whereas only fast-colonizing species increased germinability with latitude. These interactions were only detectable when analyzing germinability of the seeds, even though this trait and seed mass were correlated. The requirement for dormancy break did not correlate with latitude or temperature. The results indicate that seed development of slow colonizers may be favoured by a warmer climate, which in turn may be important for their migration capacity. Nomenclature: Tutin et al., 2001
Journal Article
Stand Composition and Structure as Indicators of Epixylic Diversity in Old-Growth Boreal Forests
This study aims to evaluate the relative contribution to biodiversity of 4 dominant types of virgin black spruce (Picea mariana) forests found in a typical regional landscape of the black spruce—moss bioclimatic domain of central Québec: mature black spruce forests with a regular structure, old black spruce forests with a regular structure, old black spruce—fir (Abies balsamea) mixed forests with 2 stories, and mixed forests with irregular structure. A total of 16 stands covering these 4 forest types were sampled to characterize forest composition and structure as well as epixylic communities. Multivariate analyses of variance were performed to evaluate to what extent the epixylic community structure differed among the 4 forest types. Results show that the old two-story and irregular forest types sustain higher species richness of epixylics per unit area; therefore, these types may be key habitats for old-growth dependent species of bryophytes and lichens. The close association of epixylics with these forest types was mainly due to better moisture conditions and the presence of greater amounts of coarse woody debris in advanced decaying stages. We also demonstrated that forest compositional and structural attributes are good indicators of epixylic diversity. Finally, we suggest that maintaining old irregular black spruce—fir mixed forests should be the primary aim of conservation strategies for old-growth forests. Nomenclature: Brodo et al., 2001; Ley & Crowe, 1999; Crum & Anderson, 1980.
Journal Article
How resilient are northern hardwood forests to human disturbance? An evaluation using a plant functional group approach
Evaluating forest ecological integrity remains a major challenge for ecologists. We analyzed understory vegetation using an approach that combined plant functional types and vertical stratification to evaluate the effects of human disturbances on the ecological integrity of sugar maple-dominated stands in southern Québec. Ecological integrity was evaluated by analyzing the divergence of understory species assemblages from those observed in comparable unmanaged forest. Multivariate analyses of biological traits revealed 13 emergent groups that share common traits associated with a similar life history strategy. Responses of these groups, of specific traits, and of understory structure to different human disturbances were tested. Nine of the 13 emergent groups varied in occurrence or diversity among disturbance types. Analyses also revealed a set of traits specifically associated with unmanaged old growth forest, indicating that species possessing these traits may be sensitive to human disturbance. Overall, the understory vegetation assemblage was found to be relatively stable among all human disturbances investigated. However, our results suggest some issues of possible long-term conservation concern given a continuation of human disturbances: (i) an increase of species associated with open environment, including exotic species; (ii) a decrease of spring geophytes; (iii) a decrease of certain shade-tolerant forbs; and (iv) a modification of understory structure by the development of a dense sapling stratum.
Journal Article