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Bodin J.,French National Institute for Agricultural Research | Bodin J.,Leibniz University of Hanover | Badeau V.,French National Institute for Agricultural Research | Bruno E.,British Petroleum | And 4 more authors.
Journal of Vegetation Science | Year: 2013

Aim: Recent vegetation changes in mountain areas are often explained by climate warming. However, effects of land-use changes, such as recolonization of abandoned pastures by forest, are difficult to separate from those of climate change. Even within forest belts, changes in stand structure due to forest management and stand maturation could confound the climate signal. Here, we evaluate the direction and rate of plant species elevation shifts in mountain forests, considering the role of stand dynamics. Location: Forests in the plains and mountains of Southeast France. Methods: We compared floristic data from the French National Forest Inventory collected in the 1980s and 1990s. They provided a large-scale (30 985 plots) and representative sample of vegetation between 0 and 2500 m a.s.l. Species response curves along the elevation and exposure gradients were fitted with a logistic regression model. In order to assess the effect of changes in successional stages of the forest stands, we compared plant species shifts in the whole set of stands with those solely in closed stands. Results: A total of 62 species shifted downward, whereas 113 shifted upward, resulting in a significant upward mean shift of 17.9 m. Upward shifting species were preferentially woody and heliophilous, suggesting a role for forest closure and maturation in the observed changes. Excluding all open forest stages from analyses, the upward trend became weaker (-3.0 m) and was not significant. Forests of the study area have undergone closure and maturation, more strongly at lower altitudes than at higher ones, producing an apparent shift of species. Conclusions: In the mountain relief of Southeast France, changes in the successional stages of stands appear as the main cause of the apparent upslope movement of forest species. Since a similar trend of forest maturation exists in large areas throughout Europe, forest dynamics should be better taken into account among the causes of vegetation changes before inferring any climate change effect. © 2012 International Association for Vegetation Science. Source

Pellissier V.,IRSTEA | Pellissier V.,CNRS Science Conservation Center | Berges L.,IRSTEA | Nedeltcheva T.,Inventaire Forestier National | And 4 more authors.
Journal of Vegetation Science | Year: 2013

Questions: How does the presence of understorey plant species vary with distance-to-edge along very large periphery-to-interior and forest patch size gradients? Can forest core and periphery species profiles be identified? What life-history traits can discriminate between forest core and forest periphery species? Location: Temperate forests in the northern half of France. Methods: Local climate, soil, stand characteristics and landscape metrics were collected on 19 989 plots in 1801 forest patches using data from the French National Forest Inventory. Very large distance-to-edge (3-1096 m) and patch size gradients (327-100 000 ha) were explored. Four logistic regression models were compared to determine the response patterns of 214 species to distance-to-edge, while controlling for patch size and local habitat quality (soil, climate and stand). The maximum distance of correlation between species occurrence and distance-to-edge was assessed using response curve characteristics. The relationships between life-history traits (habitat preference, preference for ancient forests, reproduction mode, dispersal mode, life form and autecology) and species profile according to distance-to-edge were tested. Results: Of the 214 species analysed, 40 had a core profile and 38 a periphery profile. The maximum distance of correlation was on average 748 m. Core species were more often species reproducing both by seed and vegetatively, ancient forest species, anemochores, bryophytes, pteridophytes, hemicryptophytes and acidophiles, whereas peripheral species were more often species reproducing by seed only, endozoochores, phanerophytes, thermophiles, basophiles, nitrogen-demanding and heliophiles. Conclusions: Significant periphery-to-core patterns of distribution were detected over much larger ranges than hitherto recognized for common understorey plant species. Plant traits differentiated forest core from forest periphery species. This deep gradient cannot be solely explained by the usual edge-related biotic and abiotic factors. We hypothesized that it was due to edge displacement following general reforestation since ca. 1830. This edge shift created recent forests with new habitats on former agricultural lands where dispersal-limited core species had slowly expanded and forest edge species regressed at variable speeds. This long periphery-to-interior gradient of presence has important implications for forest plant species distribution, dynamics and conservation. Periphery-to-core patterns of distribution were detected over much larger ranges (>750 m) than previously recognised for common understory plant species in 1801 forest patches of Northern France. Plant traits differentiated forest-core from forest-periphery species. This deep gradient could be due to the long-term persistence of land-use history and edge displacement following general reforestation since 1830. © 2012 International Association for Vegetation Science. Source

This article provides an assessment of the quantities of potentially exploitable timber in French forests, poplar plantations and hedges for the period 2007 to 2020. The first step consisted in computing the gross available quantities of timber, prior to deduction of the various current consumptions. This was done applying the reference silvicultural scenarios to all the plots in the French national forest inventory, on the basis of their features (species, structure, fertility, age, observed per hectare volume). Current consumption was then subtracted from these quantities. It was estimated using the annual sectoral "forest exploitation" survey in industry and an estimation of fuelwood consumption by households. The outcome is an excess availability of more than 28 million cubic metres of timber per year for bioenergy or pulp uses, and nearly 15 million cubic metres of workable timber, essentially hardwoods. Source

Tomter S.M.,Norwegian Forest And Landscape Institute | Gasparini P.,Italian Agricultural Research Council | Hennig P.,Johann Heinrich Von Thunen Institute | Polley H.,Johann Heinrich Von Thunen Institute | And 4 more authors.
Forest Science | Year: 2012

Estimates of growing stock in European countries vary mainly by using different thresholds for dbh of sample trees, as well as by the inclusion or exclusion of stump and stem top volume. European national forest inventories use dbh thresholds ranging from 0 to 12 cm in estimating the volume of growing stock. COST Action E43 has agreed to a reference definition for growing stock with a dbh threshold of 0 cm. With use of national volume distributions by dbh classes, models for estimating the proportions of growing stock between the national threshold and the 0-cm threshold were constructed. Models for characterizing growing stock distributions were tested, and their predictive abilities were investigated. Similar comparisons were made with respect to the volume of stumps and stem tops. Examples of estimation methods and the resulting percentages of these tree elements of total growing stock are presented. © 2012 by the Society of American Foresters. Source

Eva H.,European Commission - Joint Research Center Ispra | Carboni S.,Reggiani SpA | Achard F.,European Commission - Joint Research Center Ispra | Stach N.,Inventaire Forestier National | And 3 more authors.
ISPRS Journal of Photogrammetry and Remote Sensing | Year: 2010

A global systematic sampling scheme has been developed by the UN FAO and the EC TREES project to estimate rates of deforestation at global or continental levels at intervals of 5 to 10 years. This global scheme can be intensified to produce results at the national level. In this paper, using surrogate observations, we compare the deforestation estimates derived from these two levels of sampling intensities (one, the global, for the Brazilian Amazon the other, national, for French Guiana) to estimates derived from the official inventories. We also report the precisions that are achieved due to sampling errors and, in the case of French Guiana, compare such precision with the official inventory precision. We extract nine sample data sets from the official wall-to-wall deforestation map derived from satellite interpretations produced for the Brazilian Amazon for the year 2002 to 2003. This global sampling scheme estimate gives 2.81 million ha of deforestation (mean from nine simulated replicates) with a standard error of 0.10 million ha. This compares with the full population estimate from the wall-to-wall interpretations of 2.73 million ha deforested, which is within one standard error of our sampling test estimate. The relative difference between the mean estimate from sampling approach and the full population estimate is 3.1%, and the standard error represents 4.0% of the full population estimate. This global sampling is then intensified to a territorial level with a case study over French Guiana to estimate deforestation between the years 1990 and 2006. For the historical reference period, 1990, Landsat-5 Thematic Mapper data were used. A coverage of SPOT-HRV imagery at 20 m × 20 m resolution acquired at the Cayenne receiving station in French Guiana was used for year 2006. Our estimates from the intensified global sampling scheme over French Guiana are compared with those produced by the national authority to report on deforestation rates under the Kyoto protocol rules for its overseas department. The latter estimates come from a sample of nearly 17,000 plots analyzed from same spatial imagery acquired between year 1990 and year 2006. This sampling scheme is derived from the traditional forest inventory methods carried out by IFN (Inventaire Forestier National). Our intensified global sampling scheme leads to an estimate of 96,650 ha deforested between 1990 and 2006, which is within the 95% confidence interval of the IFN sampling scheme, which gives an estimate of 91,722 ha, representing a relative difference from the IFN of 5.4%. These results demonstrate that the intensification of the global sampling scheme can provide forest area change estimates close to those achieved by official forest inventories (<6%), with precisions of between 4% and 7%, although we only estimate errors from sampling, not from the use of surrogate data. Such methods could be used by developing countries to demonstrate that they are fulfilling requirements for reducing emissions from deforestation in the framework of an REDD (Reducing Emissions from Deforestation in Developing Countries) mechanism under discussion within the United Nations Framework Convention on Climate Change (UNFCCC). Monitoring systems at national levels in tropical countries can also benefit from pan-tropical and regional observations, to ensure consistency between different national monitoring systems. © 2009 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Source

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