Les comportements du blaireau européen ont été étudiés dans un terrier principal en forêt feuillue de plaine en Lorraine pendant 11 ans (2013-2023) grâce à l’utilisation de caméras. Le groupe ...familial correspond à 2-3 adultes présents toute l’année et à 1 à 4 jeunes observables hors du terrier à partir de la mi-avril (reproduction 9 années sur 11). Le toilettage est l’activité la plus fréquente directement après la sortie du terrier. La collecte de la litière a lieu durant les nuits sèches entre février et mars (relation avec les naissances des jeunes) ou en octobre (préparation des chambres de repos pour l’hiver). Les accouplements ont lieu en janvier et février. Les heures de sortie et de rentrée des blaireaux sont contrôlées par les heures de coucher et de lever du soleil mais des journées chaudes ou froides modulent également le rythme des activités journalières. Messages clés :• Lors des activités nocturnes, le blaireau présente différents comportements caractéristiques.• Certains comportements ont une saisonnalité marquée (reproduction, collecte de la litière).• Certains comportements sont modulés par des facteurs externes (pluie, cycle solaire, température).
European badgers’ behaviors have been studied over a 6-year period (2013–2018) using camera traps settled in a main sett (400 m
2
; 17 holes) in an oak forest, northeastern France. I analyzed group’s ...size, grooming, digging, bedding collecting, mating, and the emergence and return times. The burrow was inhabited by 2.8 (± 1.2) badgers. I observed between 2 and 4 new cubs each year in 5 out of 6 years, with a first emergence in mid-April. Grooming was frequent after emergence at dusk and lasted around 10 min (more frequent grooming in April after the births). Bedding collecting was a major activity in February and March during dry nights (mean duration of around 20 min) for years with births. Digging occurred only in winter 2015 and spring 2016, mainly at dusk (mean: 23 min, 2 to 90 min). Mating occurred mainly in January and February with short (< 10 min) and long (> 60 min) duration of copulation. Emergences occurred mainly between 19 and 21 h and returns between 5 and 7 h. For spring and summer, badgers emerged between 30 and 60 min before sunset but 2 h or more after sunset in autumn and winter. Returns occurred before sunrise in the middle of the night (1 h in spring and summer and 2 h or more in autumn and winter). In autumn and winter, warm nights hastened emergences time (i.e., maximum temperature higher than 10 °C) and frost nights hastened returns (i.e., minimum temperature below 0 °C).
Cet article présente une synthèse des connaissances européennes sur les groupes familiaux, la dynamique des populations et les domaines vitaux. Le cycle de reproduction des blairelles est complexe ...avec un processus d’implantation différée des ovocytes. Le pic majeur de reproduction a lieu en hiver (janvier-février) après la mise bas des jeunes issus des accouplements précédents. Seulement environ 30 % des femelles se reproduisent tous les ans (femelles dominantes en bonne santé). Le nombre de blaireautins dans une portée varie en moyenne de 1 à 3 mais la mortalité avant un an est forte souvent autour de 50 %. En Europe, la densité moyenne des blaireaux est de 1,8 ± 2,3 individus (adultes et jeunes) au km2 (4,7 en considérant les fortes densités anglaises). Cependant, des densités nettement plus faibles de l’ordre de 1 blaireau par 10 km2 sont souvent observées en Europe de l’Est. La taille des groupes familiaux est de 3,8 ± 1,2 individus (avec 2,6 ± 1 adultes) avec des variations assez faibles entre les pays (4,6 ± 2,1 individus avec les données anglaises). Le domaine vital varie fortement selon le sexe et la saison. Il est plus grand pour les mâles. Il est minimal en hiver pour les deux sexes mais plus grand en été pour les femelles. Il varie également très fortement selon la densité des animaux au km2. Ainsi, les domaines vitaux les plus grands (> 500 ha) sont observés dans les zones de plus faibles densités d’animaux (1 à 2 individus aux 10 km2) sous climat contraignant et dans les contextes de moindres ressources alimentaires (Europe de l’Est et contexte méditerranéen). Dans les zones plus favorables en contexte océanique tempéré, le domaine vital est nettement plus petit (< 100 ha) avec des densités d’animaux souvent supérieurs à 2 ou 3 individus au km2.
Le blaireau européen (Meles meles L.) est largement répandu en Europe et en France. C’est un animal social vivant généralement en groupe ou clan familial dans des terriers. Bien que le blaireau ...puisse s’installer en zone urbanisée, les mosaïques à base de chênes avec des zones ouvertes (prairies, haies, pâtures extensives) sont les biotopes largement privilégiés. Dans ces contextes, les terriers sont creusés préférentiellement dans les sols meubles en zones moyennement pentues à proximité des lisières mais loin des infrastructures humaines. La surface d’un terrier varie de quelques mètres carrés (< 100 m2) à plusieurs centaines (> 500 m2). Globalement, le nombre d’entrées, la longueur cumulée des tunnels et le nombre de chambres augmentent avec la surface. Pour les petits terriers (< 100 m2 ; dits « secondaires »), le nombre d’entrées est généralement inférieur à 10 (souvent 4 à 6), le nombre de chambres entre 0 et 3 et la longueur cumulée des tunnels inférieure à 70 m. Pour les grands terriers (au moins 200 à 300 m2 ; dits « principaux »), les entrées sont de l’ordre de 10 à 15, le nombre de chambres souvent supérieur à 10 et la longueur cumulée des tunnels de plus de 100 mètres. En Europe, la densité moyenne des terriers est de 1,1 ± 1,9 par km2. Les densités les plus fortes sont observées en Europe de l’Ouest (Irlande, Royaume-Uni, France, Espagne…) avec des valeurs moyennes entre 1,4 et 2,2 terriers par km2. Un déplacement vers l’Est (Europe centrale et de l’Est) se traduit par des densités 10 fois plus faibles souvent de moins d’un terrier par 10 km2.
Leaf phenology is a major driver of ecosystem functioning in temperate forests and a robust indicator of climate change. Both the inter-annual and inter-population variability of leaf phenology have ...received much attention in the literature; in contrast, the within-population variability of leaf phenology has been far less studied. Beyond its impact on individual tree physiological processes, the within-population variability of leaf phenology can affect the estimation of the average budburst or leaf senescence dates at the population scale. Here, we monitored the progress of spring and autumn leaf phenology over 14 tree populations (9 tree species) in six European forests over the period of 2011 to 2018 (yielding 16 site-years of data for spring, 14 for autumn). We monitored 27 to 512 (with a median of 62) individuals per population. We quantified the within-population variability of leaf phenology as the standard deviation of the distribution of individual dates of budburst or leaf senescence (SD
BBi
and SD
LSi
, respectively). Given the natural variability of phenological dates occurring in our tree populations, we estimated from the data that a minimum sample size of 28 (resp. 23) individuals, are required to estimate SD
BBi
(resp. SD
LSi
) with a precision of 3 (resp. 7) days. The within-population of leaf senescence (average SD
LSi
= 8.5 days) was on average two times larger than for budburst (average SD
BBi
= 4.0 days). We evidenced that warmer temperature during the budburst period and a late average budburst date were associated with a lower SD
BBi
, as a result of a quicker spread of budburst in tree populations, with a strong species effect. Regarding autumn phenology, we observed that later senescence and warm temperatures during the senescence period were linked with a high SD
LSi
, with a strong species effect. The shares of variance explained by our models were modest suggesting that other factors likely influence the within-population variation in leaf phenology. For instance, a detailed analysis revealed that summer temperatures were negatively correlated with a lower SD
LSi
.
Climatically controlled allocation to reproduction is a key mechanism by which climate influences tree growth and may explain lagged correlations between climate and growth. We used continent‐wide ...datasets of tree‐ring chronologies and annual reproductive effort in Fagus sylvatica from 1901 to 2015 to characterise relationships between climate, reproduction and growth. Results highlight that variable allocation to reproduction is a key factor for growth in this species, and that high reproductive effort (‘mast years’) is associated with stem growth reduction. Additionally, high reproductive effort is associated with previous summer temperature, creating lagged climate effects on growth. Consequently, understanding growth variability in forest ecosystems requires the incorporation of reproduction, which can be highly variable. Our results suggest that future response of growth dynamics to climate change in this species will be strongly influenced by the response of reproduction.
Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial ...scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes.
Resource allocation to different plant tissues is likely to be affected by high investment into fruit production during mast years. However, there is a large knowledge gap concerning species-specific ...differences in resource dynamics. We investigated the influence of mast years on stem growth, leaf production, and leaf carbon (C), nitrogen (N), and phosphorus (P) concentrations and contents in
Fagus sylvatica
,
Quercus petraea
, and
Q. robur
at continental and climate region scales using long-term data from the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) and similar datasets. We discussed the results in the light of opposing resource dynamics hypotheses: (i) resource accumulation before mast years and exhaustion after mast years (
resource storage hypothesis
), (ii) shifting resources from vegetative to generative compartments (
resource switching hypothesis
), and (iii) investing resources concurrently in both vegetative and generative compartments (
resource matching hypothesis
). Linear mixed-effects modelling (LMM) showed that both stem growth and leaf production were negatively influenced by weather conditions which simultaneously lead to high fruit production. Thus, the impact of generative on vegetative growth is intermixed with effects of environmental factors. Superposed epoch analyses and LMM showed that for mast behaviour in
F. sylvatica
, there are indicators supporting the
resource storage
and the
resource switching hypotheses
. Before mast years, resources were accumulated, while during mast years resources switched from vegetative to generative tissues with reduced stem and leaf growth. For the
Quercus
species, stem growth was reduced after mast years, which supports the
resource storage hypothesis
. LMM showed that leaf C concentrations did not change with increasing fruit production in neither species. Leaf N and P concentrations increased in
F. sylvatica
, but not in
Quercus
species. Leaf N and P contents decreased with increasing fruit production in all species, as did leaf C content in
F. sylvatica
. Overall, our findings suggest different resource dynamics strategies in
F. sylvatica
and
Quercus
species, which might lead to differences in their adaptive capacity to a changing climate.
► We investigated the tree-size effect on sensitivity to climate. ► Study was led on a multi-species network at broad scale. ► Only shade-tolerant species display changes in sensitivity among ...size-classes. ► Increasing local xericity induces increasing differences in sensitivity.
In most dendrochronological studies, climate–growth relationships are established on dominant trees to minimize non-climatic signals. However, response to environmental factors may be affected by tree-size, which begs the question of the representativeness of dominant trees on the stand level. To highlight the variations in climate–growth relationships among sizes and species, under a wide range of ecological conditions (climate and soil properties), 61 pure even-aged stands were sampled across France. At each stand, two tree-ring chronologies were established from 10 big- to 10 small-diameter trees. Our objectives were, (1) to assess variations in climate sensitivity between the two size-diameter classes, and (2) to investigate the role of species and ecological conditions on these variations. The climate-growth relationships were evaluated from 122 tree-ring chronologies (1
220 trees) through extreme growth years and correlation function analyses. Sensitivity to climate of shade-intolerant and moderately shade-tolerant species (
Picea abies (L.) Karst.,
Pinus sylvestris L. and
Quercus petraea (Matt.) Liebl.) remained constant between the size-diameter classes for both temperature and hydric balance, while the shade-tolerant species
Abies alba Mill. and
Fagus sylvatica L. displayed significant differences, with larger trees being more sensitive to summer drought than smaller trees. This difference increased with increasing climatic xericity. Our results suggest that, for shade-tolerant species, (1) big trees could be more sensitive to climatic change especially under xeric climate, and (2) future tree ring studies should include trees stratified by size to produce unbiased estimation of sensitivity to climate.
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