Office National des Forets

Ars-en-Ré, France

Office National des Forets

Ars-en-Ré, France
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Lebourgeois F.,Agro ParisTech | Lebourgeois F.,French National Institute for Agricultural Research | Gomez N.,Office National des Forets | Pinto P.,French National Institute for Agricultural Research | And 3 more authors.
Forest Ecology and Management | Year: 2013

In most dendroecological studies, climate-tree growth relationships are established for trees growing on pure stands. However, response to climate may be affected by inter-species interactions and local constraints, which beg the question of the effect of mixture on tree growth response under various ecological conditions. To assess these effects, climate-tree growth relationships of pure Abies alba stands were compared to those of three different mixtures: A. alba with Fagus sylvatica, with Picea abies and with both species. 151 stands (456 A. alba trees) were sampled in the Vosges mountains in north-eastern France under three contrasted climates, from low altitude and dry conditions (mean precipitation in July <85. mm and altitude <600. m) to high altitude and humid conditions (P July >115. mm and alt. <900. m). We sampled adult trees and homogeneous stand conditions to clearly assess differences in sensitivity to climate. Climate-tree growth relationships were evaluated from 12 A. alba chronologies (four mixtures. ×. three climatic conditions) through pointer years and response function analyses. Late previous summer conditions and current summer soil water deficit and temperature played a major role on A. alba growth. Results showed greater sensitivity to temperature at high elevation, and to summer drought at low altitude and under dry conditions. Mixture allowed maintaining a higher level of A. alba growth during extreme climatic events and reduced A. alba response to summer drought especially under the driest contexts. Different facilitation processes may explain mixture effects such as changes in rooting depth, water input by stemflow and rainfall interception. This differentiated functioning of mixed forests highlights their importance for adapting forest management to climate change. © 2013 Elsevier B.V.

van der Heijden G.,French National Institute for Agricultural Research | Legout A.,French National Institute for Agricultural Research | Nicolas M.,Office National des Forets | Ulrich E.,Office National des Forets | And 2 more authors.
Forest Ecology and Management | Year: 2011

Since the 1980s, atmospheric deposition acidity has generally decreased in European forest ecosystems. However, at many sites, little or no sign of recovery has been observed yet. Concerns are rising about the sustainability of these ecosystems because of reduced nutrients inputs in atmospheric deposition and the increase in biomass harvesting to supply bio-energy. We used a silver fir plot of the French monitoring network (RENECOFOR, site SP57) typical of the ecosystems on sandstone in the Vosges Mountains, to investigate its functioning and its response facing past and possible future changes. We (1) calculated 12-year-mean "input-output" nutrient budgets, (2) measured the change in soil exchangeable cations and anions, (3) used monitoring data to calibrate a process oriented biogeochemical model, NuCM, that was then used to (4) simulate the consequences of two main scenarios and their combinations: constant or reduced atmospheric deposition, and traditional or whole-tree harvesting. Mean term changes in exchangeable nutrients and input-output budgets showed a loss of exchangeable sulphate and base cations, the level of which depended on the method. This combined efflux induced an acidification of soil solution and an alkalinisation of the soil. The model NuCM was successfully calibrated and scenarios were implemented. A slight recovery was simulated when deposition was maintained constant but combined acid and nutrient atmospheric deposition reduction delayed recovery. Whole-tree harvesting drastically decreased soil fertility compared to traditional silviculture. Hence, biomass harvesting in forests on poor soils may counter recovery in the future. © 2010 Elsevier B.V.

Lebourgeois F.,Agro ParisTech | Rathgeber C.B.K.,French National Institute for Agricultural Research | Ulrich E.,Office National des Forets
Journal of Vegetation Science | Year: 2010

Questions: (1) How do extreme climatic events and climate variability influence radial growth of conifers (silver fir, Norway spruce, Scots pine)? (2) How do elevation and soil water capacity (SWC) modulate sensitivity to climate? Location: The sampled conifer stands are in France, in western lowland and mountain forests, at elevations from 400 to 1700 m, and an SWC from 50 to 190 mm. Methods: We established stand chronologies for total ring width, earlywood and latewood width for the 33 studied stands (985 trees in total). Responses to climate were analysed using pointer years and bootstrapped response functions. Principal component analysis was applied to pointer years and response function coefficients in order to elucidate the ecological structure of the studied stands. Results: Extreme winter frosts are responsible for greater growth reductions in silver fir than in Norway spruce, especially at the upper elevation, while Scots pine was the least sensitive species. Exceptional spring droughts caused a notable growth decrease, especially when local conditions were dry (altitude<1000 m and SWC<100 mm for silver fir, western lowlands for Scots pine). Earlywood of silver fir depended on previous September and November and current-year February temperature, after which current June and July water supply influenced latewood. Earlywood of Norway spruce was influenced by previous September temperature, after which current spring and summer droughts influenced both ring components. In Scots pine, earlywood and latewood depended on the current summer water balance. Local conditions mainly modulated latewood formation. Conclusions: If the climate becomes drier, low-elevation dry stands or trees growing in western lowlands may face problems, as their growth is highly dependent on soil moisture availability. © 2009 International Association for Vegetation Science.

Lebourgeois F.,Agro ParisTech | Lebourgeois F.,French National Institute for Agricultural Research | Merian P.,Agro ParisTech | Merian P.,French National Institute for Agricultural Research | And 3 more authors.
Trees - Structure and Function | Year: 2012

Temporal instability of climate signal in tree-ring width of the five dominant species (Pinus nigra, P. sylvestris, P. uncinata, Abies alba, Fagus sylvatica) growing under Mediterranean mountainous climate was studied over the last century (1910-2004). To disentangle the tree-climate-site complex, the effects of both soil water availability (SWA) (dry, mesic and humid sites) and altitude (from 430 to 1,690 m) were investigated on the response patterns. Responses to climate were analysed using bootstrapped correlation coefficients from 17 ring-width chronologies built from 293 trees sampled in 64 stands in South-Eastern France. Temporal analyses were performed considering forty-six 50-years intervals (from 1910-1959 to 1955-2004). May-June drought was the primary limiting factor. For P. sylvestris, summer precipitation also played a key role. F. sylvatica was the less responding species with no clear common pattern. Low SWA led to an increasing correlation with precipitation in May for P. nigra and A. alba. Precipitation from May to August prevailed on the driest conditions for P. sylvestris. Correlation analyses suggested that warm autumn or winter enhanced growth, except for F. sylvatica. For P. nigra, the importance of April temperature increased with increasing altitude. Temporal analyses revealed a stability of sensitivity for the highest contexts (P. uncinata and F. sylvatica). At lower altitudes, the correlation with minimum temperature in April increased while temperature more often exceeded the threshold of 0°C over the last decades. For precipitation, a decrease in the strength of correlation was observed without close relationships with local xericity. © 2011 Springer-Verlag.

Jonard M.,Catholic University of Leuven | Legout A.,French National Institute for Agricultural Research | Nicolas M.,Office National des Forets | Dambrine E.,French National Institute for Agricultural Research | And 4 more authors.
Global Change Biology | Year: 2012

Since the late 1970s, several long-term ecological studies were conducted to better understand the biogeochemical functioning of Norway spruce stands in the Ardennes as these nutrient-poor ecosystems were subject to high levels of acid deposition and exhibited symptoms of tree health decline. Between 1978 and 2009, acid deposition declined sharply, especially sulfur and to a lesser extent nitrogen deposition. The aim of this study was (i) to determine if the Norway spruce stands recovered after the reduction of acid deposition and (ii) to explain why such a recovery occurred or not. Therefore, we collected data from different projects carried out in the Ardennes to characterize the long-term temporal trends in soil solution chemistry, foliar nutrition, and crown condition. In parallel, a model describing the nutrient cycling in forests (NuCM) was calibrated and used to check the consistency of the observed temporal trends and to explain them. The soil solution concentration of most of the elements decreased between 1978 and 2002, which was ascribed to a decrease in atmospheric deposition. For potassium, a decline in the exchangeable pool was also showed based on the simulation carried out with NuCM. As nitrogen (N) deposition remained at an elevated level, Norway spruce stands were progressively saturated in N and mineral nutrition became more and more unbalanced. Except the foliar N and Al concentration that remained constant and increased respectively, the foliar concentration of all other nutrients decreased between 1993 and 2009, which can be explained by the decrease in ion concentration in solution. These nutritional disorders weakened trees and were probably exacerbated during the 2003 summer drought, after which symptoms of vitality loss progressively appeared. In these N-saturated ecosystems, the N cycle was disrupted by this health decline, which increased NO 3 - leaching reinforcing soil acidification and risk of aluminum (Al) toxicity. © 2011 Blackwell Publishing Ltd.

Agency: European Commission | Branch: H2020 | Program: BBI-RIA | Phase: BBI.VC2.R5-2015 | Award Amount: 4.20M | Year: 2016

EFFORTE draws a red line through critical, cost/benefit driving processes, and environmentally concerns of todays forestry. Starting with efficient fulfilment of various customer demands the red line goes along efficient utilization of Big Data sources, present knowledge and critical new knowledge foreseen as outcomes from this project. Technical development and mechanization has been a winning concept for high productivity now emphasizing more gentle methods and just in time deliveries to different industry customers. This is possible to reach if new knowledge, improved methods and technical development are combined with better transfer of information and data from different sources (e.g processes, geo data from LiDAR scanning, other conditions such as weather data etc).These Big Data sources have been available for some years, but it is not until recently that hardware, data communication and merging possibilities enable full potential for a revolution of new applications. In the EFFORTE proposal we have identified three main subjects that have specific importance for efficiency, productivity and environmental concern in forest practice. Two of these implies to increasing crucial knowledge and the third, Big Data applications, combines the new knowledge with high resolution information sources into practice increasing efficiency in forest management and the connected value chains. The main objectives of EFFORTE are: i) To develop scientifically firm and techno-economically feasible methodology to predict trafficability prior to forest operations. ii) To increase forest growth and productivity of tree planting and young stand management iii) To develop, customize and pilot modern Big data solutions that will increase productivity and decrease negative environmental impact (e.g. soil, water and reduced fuel consumption). By EFFORTE we expect to make difference in efficiency, productivity and sustainability for a growing Bio-based economy in Europe.

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.

Othmani A.,French National Center for Scientific Research | Lew Yan Voon L.F.C.,French National Center for Scientific Research | Stolz C.,French National Center for Scientific Research | Piboule A.,Office National des Forets
Pattern Recognition Letters | Year: 2013

Due to the increasing use of Terrestrial Laser Scanning (TLS) systems in the forestry domain for forest inventory, the development of software tools for the automatic measurement of forest inventory attributes from TLS data has become a major research field. Numerous research work on the measurement of attributes such as the localization of the trees, the Diameter at Breast Height (DBH), the height of the trees, and the volume of wood has been reported in the literature. However, to the best of our knowledge the problem of tree species recognition from TLS data has received very little attention from the scientific community. Most of the research work uses Airborne Laser Scanning (ALS) data and measures tree species attributes on large scales. In this paper we propose a method for individual tree species classification of five different species based on the analysis of the 3D geometric texture of the bark. The texture features are computed using a combination of the Complex Wavelet Transforms (CWT) and the Contourlet Transform (CT), and classification is done using the Random Forest (RF) classifier. The method has been tested using a dataset composed of 230 samples. The results obtained are very encouraging and promising. © 2013 Elsevier B.V. All rights reserved.

Bouvier M.,IRSTEA | Durrieu S.,IRSTEA | Fournier R.A.,Université de Sherbrooke | Renaud J.-P.,Office National des Forets
Remote Sensing of Environment | Year: 2015

This study proposed modifying the conceptual approach that is commonly used to model development of stand attribute estimates using airborne LiDAR data. New models were developed using an area-based approach to predict wood volume, stem volume, aboveground biomass, and basal-area across a wide range of canopy structures, sites and LiDAR characteristics. This new modeling approach does not adopt standard approaches of stepwise regression using a series of height metrics derived from airborne LiDAR. Rather, it used four metrics describing complementary 3D structural aspects of the stand canopy. The first three metrics were related to mean canopy height, height heterogeneity, and horizontal canopy distribution. A fourth metric was calculated as the coefficient of variation of the leaf area density profile. This fourth metric provided information on understory vegetation. The models that were developed with the four structural metrics provided higher estimation accuracy on stand attributes than models using height metrics alone, while also avoiding data over-fitting. Overall, the models provided prediction error levels ranging from 12.4% to 24.2%, depending upon forest type and stand attribute. The more homogeneous coniferous stand provided the highest estimation accuracy. Estimation errors were significantly reduced in mixed forest when separate models were developed for individual stand types (coniferous, mixed and deciduous stands) instead of a general model for all stand types. Model robustness was also evaluated in leaf-off and leaf-on conditions where both conditions provided similar estimation errors. © 2014 Elsevier Inc.

Lebourgeois F.,Agro ParisTech | Pierrat J.-C.,Agro ParisTech | Perez V.,Agro ParisTech | Piedallu C.,Agro ParisTech | And 2 more authors.
International Journal of Biometeorology | Year: 2010

After modeling the large-scale climate response patterns of leaf unfolding, leaf coloring and growing season length of evergreen and deciduous French temperate trees, we predicted the effects of eight future climate scenarios on phenological events. We used the ground observations from 103 temperate forests (10 species and 3,708 trees) from the French Renecofor Network and for the period 1997-2006. We applied RandomForest algorithms to predict phenological events from climatic and ecological variables. With the resulting models, we drew maps of phenological events throughout France under present climate and under two climatic change scenarios (A2, B2) and four global circulation models (HadCM3, CGCM2, CSIRO2 and PCM). We compared current observations and predicted values for the periods 2041-2070 and 2071-2100. On average, spring development of oaks precedes that of beech, which precedes that of conifers. Annual cycles in budburst and leaf coloring are highly correlated with January, March-April and October-November weather conditions through temperature, global solar radiation or potential evapotranspiration depending on species. At the end of the twenty-first century, each model predicts earlier budburst (mean: 7 days) and later leaf coloring (mean: 13 days) leading to an average increase in the growing season of about 20 days (for oaks and beech stands). The A2-HadCM3 hypothesis leads to an increase of up to 30 days in many areas. As a consequence of higher predicted warming during autumn than during winter or spring, shifts in leaf coloring dates appear greater than trends in leaf unfolding. At a regional scale, highly differing climatic response patterns were observed. © 2010 ISB.

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