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1
Petersson, Linda K., Magnus Löf, Anna M. Jensen, Daryl R. Chastain et Emile S. Gardiner. « Sprouts of shoot-clipped oak (Quercus alba and Q. robur) germinants show morphological and photosynthetic acclimation to contrasting light environments ». New Forests 51, no 5 (14 novembre 2019) : 817–34. http://dx.doi.org/10.1007/s11056-019-09762-5.
Texte intégralRésumé :
AbstractSprouting by woody plants can increase species resilience to disturbance and foster regeneration during periods with little recruitment from seed. Though sprouting often plays a critical role in oak forest regeneration, there is little information available on sprouting capacity and sprout physiology at the seedling stage, particularly for new germinants. This study compared sprouting capacity and sprout photosynthesis of shoot-clipped germinants of two temperate oaks established in contrasting light environments. We studied the North American Quercus alba and the European Q. robur, both are in the section Quercus and appear to share similar biological and ecological requirements. Sprouting capacity for both species was enhanced under high light availability (29% more sprouts per plant), a response not previously noted for oak germinants. Seedling sprouts acclimated to high light with a 34% decrease in leaf area ratio, a 56% increase in leaf mass per area, and a 49% increase in the light-saturated maximum photosynthetic rate. Though both species appeared similarly adapted to shoot loss, a greater sprouting capacity (29% more sprouts per plant) and plant-level net photosynthesis (73% higher) was observed for Q. robur, regardless of light environment. As naturally regenerated oak seedlings in forest understories often experience disturbance or stress resulting in shoot loss or die-back, our results highlight the importance of the light environment during early plant development. Our comparison of temperate oaks from different continents should facilitate exchange of successful stand regeneration practices within the range of temperate oak forests.
2
Franc, Niklas. « Standing or downed dead trees — does it matter for saproxylic beetles in temperate oak-rich forest ? » Canadian Journal of Forest Research 37, no 12 (décembre 2007) : 2494–507. http://dx.doi.org/10.1139/x07-096.
Texte intégralRésumé :
For conservation of forest biodiversity, dead wood in the form of logs, snags, or cut high stumps is sometimes left or created when forests are harvested. In Scandinavia, such dead wood usually comes from conifers. For forests in temperate regions, few studies have analysed composition and species richness of beetles using dead wood of oaks ( Quercus spp). In this study in southern Sweden, I examined the occurrence of saproxylic beetles trapped at lying (logs) and standing (snags) dead wood of European oaks ( Quercus robur L. and Quercus petraea (Mattuschka) Liebl.) in 13 oak-rich mixed forests of relatively high conservation value. The assemblage of beetles differed strikingly between the lying and standing dead wood. Traps on lying dead wood, compared to traps on standing dead wood, had more fungivores and fewer primary and secondary wood boring species. Of 94 species tested for individual substrate preferences, 48 showed prevalence for different trap/substrate types. Absolute species richness was significantly higher on logs than snags, but a smaller proportion of the snag substrate or snag beetles may have been sampled. For red-listed beetles, no differences in their species richness were detected among substrates. These results suggest that logs of dead oaks are valuable and that both snags and logs of oak should be retained and, if needed, created in forestry, such that they are continuously available in stands.
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Harrington, Constance. « Oak Forest Ecosystems : Ecology and Management for Wildlife ». Forest Science 48, no 4 (1 novembre 2002) : 792–93. http://dx.doi.org/10.1093/forestscience/48.4.792.
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Abstract Oaks (Quercus spp.) are important components in many temperate forest ecosystems, and a new book that synthesizes information on their management is always of interest. The intent of this book was to bring together knowledge from a diverse group of people who study oak forests and make that information available to those interested in managing those forests in a sustainable manner for wildlife. I think the authors have done a good job in achieving their objectives.
4
Götmark, Frank. « Experiments for alternative management of forest reserves : effects of partial cutting on stem growth and mortality of large oaks ». Canadian Journal of Forest Research 39, no 7 (juillet 2009) : 1322–30. http://dx.doi.org/10.1139/x09-045.
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Although protected forests are usually kept as free of human disturbance as possible, careful cutting may favour biodiversity in such areas. However, the use of heavy machinery during cutting operations may have a negative impact on protected forests. The large oaks ( Quercus spp.) found in many temperate nature reserves have a rich associated biodiversity. In 25 conservation forests in Sweden, the basal area growth and mortality of 250 large oaks (31–110 cm DBH) were compared between plots that were partially cut to promote the growth and survival of oaks and undisturbed plots. Each forest had one treatment plot (1 ha) and one undisturbed reference plot (1 ha) with similar levels of canopy cover. In 2002–2003, about 25% of the basal area was harvested in treatment plots, thereby increasing canopy openness from 14% to 33%. Cutting increased the mean relative basal area growth of large oaks (49% by plot, 22% by tree) after four seasons (P = 0.026). However, in nine forests, the growth rate was not higher in the treated plot than in the reference plot. Mortality, apparently due to cutting, was recorded only in one forest, where 18 large oaks died. Tree condition (percentage of dead large branches in crown) was the best (negative) predictor of growth rate, and openness around oak crown was also a (positive) predictor. Partial cutting favoured the growth of oaks and may be recommended, but a “hands-off” policy is also effective for these conservation forests.
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Castillo-Mendoza, Elgar, Alejandro Zamilpa, Manasés González-Cortazar, Ever A. Ble-González et Efraín Tovar-Sánchez. « Chemical Constituents and Their Production in Mexican Oaks (Q. Rugosa, Q. Glabrescens and Q. Obtusata) ». Plants 11, no 19 (4 octobre 2022) : 2610. http://dx.doi.org/10.3390/plants11192610.
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Mexico is considered one of the main regions of diversification of the genus Quercus (oaks). Oak species are one of the most important tree groups, particularly in temperate forests, due to its diversity and abundance. Some studies have shown that oak contains specialized metabolites with medicinal importance. In this work, the acetonic extract from leaves of three Mexican oaks (Quercus rugosa, Q. glabrescens, and Q. obtusata) was separated using thin-layer chromatography and column chromatography. Chemical identification of the major compounds was determined using high-performance liquid chromatography and nuclear magnetic resonance. Nineteen compounds were identified, three belonging to the terpenoid family (ursolic acid, β−amyrin, and β−sitosterol) and 16 from the phenolic family. Of the isolated compounds, seven are new reports for oak species (scopoletin, ursolic acid, β-amyrin, luteolin−7−O−glucoside, kaempferol−3−O−sophoroside, kaempferol−3−O−glucoside, and kaempferol−3−O−sambubioside). More compounds were identified in Q. rugosa followed by Q. glabrescens and then Q. obtusata. The characterization of specialized metabolites in oak species is relevant, from both phytocentric and anthropocentric perspectives.
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PÉNZES, ZSOLT, CHANG-TI TANG, GRAHAM N. STONE, JAMES A. NICHOLLS, SZABINA SCHWÉGER, MIKLÓS BOZSÓ et GEORGE MELIKA. « Current status of the oak gallwasp (Hymenoptera : Cynipidae : Cynipini) fauna of the Eastern Palaearctic and Oriental Regions ». Zootaxa 4433, no 2 (12 juin 2018) : 245. http://dx.doi.org/10.11646/zootaxa.4433.2.2.
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Cynipid gallwasps comprise 1364 species worldwide, predominantly in temperate regions of the Holarctic. The vast majority of recorded species are from the Nearctic and the Western Palaearctic, both of which are long-standing centers of research on the taxonomy and biology of this group. In contrast, the Eastern Palaearctic and the Oriental Region faunas are much less studied, but potentially extremely rich. Previously recorded species richness of cynipid groups in the Eastern Palaearctic and Oriental regions probably represents a significant underestimate. This is particularly marked for gallwasps associated with oaks (tribe Cynipini), as has been shown by recent works, which describe many new species galling oaks in the subgenera Quercus and Cyclobalanopsis and plants of the other Fagaceae genera (Castanopsis, Lithocarpus and Castanea). In the present paper, we summarise the current knowledge of oak gallwasps in the regions that extend from Pakistan, through Nepal and China to Japan and south to Indonesia, and list a total of 97 species of Cynipini from the area.
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Canadell, Josep, et Ferran Rodà. « Root biomass of Quercusilex in a montane Mediterranean forest ». Canadian Journal of Forest Research 21, no 12 (1 décembre 1991) : 1771–78. http://dx.doi.org/10.1139/x91-245.
Texte intégralRésumé :
Biomass allocation to roots was studied in holm oak (Quercusilex L.), a dominant evergreen tree in broad-leaved sclerophyllous Mediterranean forests. The root systems of 32 single-stemmed holm oaks growing in shallow soils on largely unfissured bedrock were excavated in a mesic site and a xeric site in the Montseny Mountains (northeast Spain). Individual root:shoot biomass ratios (roots with diameter <1 cm not included) of single-stemmed trees were significantly higher in the xeric site (mean 0.45) than in the mesic site (mean 0.37), probably reflecting the lower water availability and higher light availability in the xeric site. It is concluded that single-stemmed holm oaks have higher root:shoot ratios than most temperate forest trees, particularly so when growing on a xeric site. Root:shoot ratios of single-stemmed trees were not linearly correlated with dbh. Allometric regressions of root biomass on dbh did significantly differ between sites. Roots <1 cm in diameter were sampled with soil cores in the mesic site. Holm oaks ≥5 cm dbh in a stand dominated by single-stemmed trees on the mesic site had an aboveground biomass of 160 t/ha and a belowground biomass of 63 t/ha. The belowground biomass was composed of 30 t/ha of root crowns plus roots >5 cm in diameter, 17 t/ha of roots 1–5 cm in diameter, and 16 t/ha of roots <1 cm in diameter. The xeric stand was dominated by multistemmed holm oaks with massive root crowns developed after repeated coppicing. Three multistemmed trees were excavated, yielding a mean root:shoot ratio of 1.2. Through resprouting from root crowns, managed or disturbed holm oak forests can accumulate a belowground biomass greater than that displayed aboveground: 91 t/ha (excluding roots <1 cm in diameter) and 79 t/ha, respectively, in our xeric stand.
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Kremer, A. « Social Broadleaves. EUFORGEN genetic conservation network ». Forest Systems 9, no 4 (1 décembre 2001) : 117–23. http://dx.doi.org/10.5424/699.
Texte intégralRésumé :
The «Social Broadleaves» EUFORGEN network include temperate oaks and beeches, as broadleaved species living in large population in pure or mixed forest. Most important economic Social Broadleaves have a wide distribution (Q. petraea, Q. robur and F. sylvatica). They occupy also a large ecological range, giving many opportunities for natural selection to differentiate populations. Species delineation is imprecise in oaks, and various names and classification are proposed in different countries. The main objective of the network is the development of «joint, long-term, practically oriented gene conservation strategies». Most urgent needs were expressed by each member mainly in the area of in situ conservation methods. Other objectives are to «stimulate collaborative initiatives related to conservation activities». These initiatives concern dissemination of information and research results, and the raising of awareness on conservation issues. A review of the current knowledge on genetic structure and dynamics is summarised in order to define the Genetic Resource Conservation Strategy for Social Broadleaves. There is an important morphological variation that encompasses taxonomic units. There is clearly a need to provide some common methodology for assigning oak trees to taxonomic units. Oak species belonging to the same botanical section intercross naturally. Natural hybridization can be seen as a mechanism to enrich genetic diversity. Oaks and beeches are preferentially outbreeding, with extensive gene flow by pollen. There is a common agreement that practical actions should be taken, even if knowledge on population structure is still lacking. Conservation strategies should be established not only to maintain diversity but also to safeguard the evolutionary potential of the species. In situ conservation measures are implemented in most countries for both Fagus and Quercus (mostly Q. petraea and Q. robur) based mostly on pragmatic rules. Ex situ measures are promoted in a few countries in the case of oaks. No additional measures are requested by the different members in the case of beech, since natural regeneration is widely used to renew the stands.
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Semerikova, S. A., Kh U. Aliev, N. V. Semerikov et V. L. Semerikov. « Phylogeography of Oak Species in the Caucasus Based on the Results of Chloroplast DNA Analysis ». Генетика 59, no 7 (1 juillet 2023) : 772–88. http://dx.doi.org/10.31857/s001667582307010x.
Texte intégralRésumé :
In order to study the biogeography and history of the temperate biota of the Caucasian region, one of the centers of biological diversity of Eurasia, the phylogeographic structure of the chloroplast DNA of roburoid oaks (Quercus L. sect. Quercus, Fagaceae) was studied. We analyzed 926 trees of five species (Quercus robur, Q. petraea, Q. pubescens, Q. hartwissiana, Q. macranthera) from 70 populations located in different parts of the Caucasus. Sequencing of five fragments with a total length of more than 10 000 bp revealed eight haplotypes, which were typed using chloroplast microsatellite loci (cpSSR), sequencing, and restriction analysis. The Quercus phylogenetic tree, which includes 34 chloroplast haplotypes of Western Eurasian and East Asian roburoid species, confirmed the monophyly of roburoid oaks, which form several lines that do not have supported topological relationships with each other. The haplotypes identified in the Caucasus belong to two divergent Western Eurasian lineages. These haplotypes are endemic for the Eastern Black Sea and Caucasian region and do not have related haplotypes beyond its borders, which indicates the long-term presence of oaks in the Caucasus and the historical links of the oaks of the Caucasian region with the Eastern Crimea and Eastern Turkey in the absence of chloroplast DNA exchanges with the Eastern European part of the range. The results of the present study indicate that Caucasian populations could not significantly contribute to the colonization of northern territories, and were not influenced by more northern populations, at least through seed transfer. The distribution zones of the Caucasian haplotypes almost do not intersect with each other, occupying certain geographical areas, probably due to the settlement from individual glacial refugia and genetic drift. The geographical structure of chloroplast DNA variability indicates a long-term presence of oak in addition to Western Transcaucasia (Colchis refugium), in the regions of the Northwestern, Central, Eastern Caucasus and the Lesser Caucasus. The coincident composition of the haplotypes of the studied oak species within the geographic regions indicates the long-term coexistence of different species in different parts of the Caucasus.
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Vincent-Barbaroux, Cécile, Daniel Berveiller, Caroline Lelarge-Trouverie, Rodrigo Maia, Cristina Máguas, João Pereira, Manuela M. Chaves et Claire Damesin. « Carbon-use strategies in stem radial growth of two oak species, one Temperate deciduous and one Mediterranean evergreen : what can be inferred from seasonal variations in the δ13C of the current year ring ? » Tree Physiology 39, no 8 (17 mai 2019) : 1329–41. http://dx.doi.org/10.1093/treephys/tpz043.
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Abstract Tree ring synthesis is a key process in wood production; however, little is known of the origin and fate of the carbon involved. We used natural 13C abundance to investigate the carbon-use process for the ring development in a temperate deciduous (Quercus petraea (Matt.) Liebl.) and a Mediterranean evergreen (Quercus ilex L.) oak. The sapwood carbon reserves, phloem sucrose contents, stem respired CO2 efflux and their respective carbon isotope compositions (δ13C) were recorded over 1 year, in the native area of each species. The seasonal δ13C variation of the current year ring was determined in the total ring throughout the seasons, as well as in slices from the fully mature ring after the growth season (intra-ring pattern). Although the budburst dates of the two oaks were similar, the growth of Quercus ilex began 50 days later. Both species exhibited growth cessation during the hot and dry summer but only Q. ilex resumed in the autumn. In the deciduous oak, xylem starch storage showed clear variations during the radial growth. The intra-ring δ13C variations of the two species exhibited similar ranges, but contrasting patterns, with an early increase for Q. petraea. Comparison between δ13C of starch and total ring suggested that Q. petraea (but not Q. ilex) builds its rings using reserves during the first month of growth. Shifts in ring and soluble sugars δ13C suggested an interspecific difference in either the phloem unloading or the use of fresh assimilate inside the ring. A decrease in ring δ13C for both oaks between the end of the radial growth and the winter is attributed to a lignification of ring cell walls after stem increment. This study highlighted the differences in carbon-use during ring growth for evergreen and deciduous oaks, as well as the benefits of exploring the process using natural 13C abundance.
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Jarvis, Devra I. « Pollen Evidence of Changing Holocene Monsoon Climate in Sichuan Province, China ». Quaternary Research 39, no 3 (mai 1993) : 325–37. http://dx.doi.org/10.1006/qres.1993.1039.
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AbstractPollen evidence from Lake Shayema, Mianning County, was obtained to examine postglacial vegetation and climatic change in southwestern Sichuan, China. The sclerophyllous character of the region's warm temperate vegetation today is a reflection of extreme drought in spring before the onset of the Asian monsoons. The pollen record displays several changes in the vegetation over the last 11,000 yr. From 11,000 to 9100 yr B.P., cold-tolerant species, such as Abies , Betula, and deciduous oaks, dominated the vegetation. Between 9100 and 7800 yr B.P., the abundance of deciduous oaks decreased and evergreen oaks increased, as did Tsuga and mesic deciduous species. This change suggests a warming climate with increased precipitation. From 7800 to 4000 yr B.P., sclerophyllous species increased at the expense of mesic deciduous species, an indication that precipitation was becoming more seasonal. Except for increased disturbance starting ca. 1000 yr B.P., the predominance of sclerophyllous vegetation continued until today. The pollen results are compatible with proposed global circulation hypotheses of a strengthened monsoon system during the early to mid Holocene.
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Nyandiga, Charles O., et Guy R. McPherson. « Germination of two warm-temperate oaks, Quercusemoryi and Quercusarizonica ». Canadian Journal of Forest Research 22, no 9 (1 septembre 1992) : 1395–401. http://dx.doi.org/10.1139/x92-185.
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Quercusemoryi Torr. (emory oak) and Quercusarizonica Sarg. (Arizona white oak) are the dominant trees in many of the oak savannas and woodlands of Arizona and northern Mexico. The objectives of this study were (i) to evaluate germination on two media as influenced by storage and stratification and (ii) to determine the effects of oak canopy and depth of burial on acorn viability and germination. Germination was higher (P < 0.05) on filter paper than in mineral soil in laboratory trials. Maximum germination of Q. emoryi in the field was observed at a depth of 7.5 cm (29%), with only 5% germination at the soil surface. Germination of Q. arizonica at 7.5 and 15 cm (73%) was not different (P > 0.10) but exceeded germination at the surface (17%). These results represent the first reported germination of either species and indicate that recruitment into mature oak woodlands is not limited by germination.
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Sütő, D., J. Farkas, S. Siffer, G. Schally et K. Katona. « Spatiotemporal pattern of wild boar rooting in a Central European dry oak forest ». European Journal of Forest Research 139, no 3 (6 décembre 2019) : 407–18. http://dx.doi.org/10.1007/s10342-019-01248-5.
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AbstractWild boar (Sus scrofa) density has significantly increased worldwide. In Europe, oak acorns are basic diet items for the species. However, regeneration of temperate oak forests has become excessively low. Thus, better understanding of the patterns and dynamics of wild boar rooting and the spatiotemporal relationship between the acorn density and the rooting has special importance. In our study, the acorn density, the presence and intensity of the rooting were measured monthly in a 28-ha oak forest stand between 2016 October and 2019 April. Study site was divided to 400 m2 grid cells to investigate the spatiotemporal patterns of the rooting. Comparing the acorn densities, we stated that in the first 2 years, but not in the third one, the oaks were masting. During the acorn-rich periods (October–April), significant inter-annual differences were found in the proportions of the disturbed area between the non-mast and the other two mast years. Throughout our observations, 9.12% of the cells stayed undisturbed. On average, in 12.59% of the cells new rooted patches appeared, and 15.6% of them was repeatedly disturbed. Rooting were mainly litter disturbances in 71.75% of cases. Throughout acorn fall periods (September–November), the most intensively rooted sites were the poorest in acorns, while the unrooted sites were the richest. Our results demonstrate that wild boars have a great effect on acorn density and on the whole forest by rooting almost the entire ground surface at least once, but also the masting of the oaks has a crucial role in their rooting dynamics.
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Arenas-Navarro, Maribel, Felipe García-Oliva, Teresa Terrazas, Andrés Torres-Miranda et Ken Oyama. « Leaf Habit and Stem Hydraulic Traits Determine Functional Segregation of Multiple Oak Species along a Water Availability Gradient ». Forests 11, no 8 (18 août 2020) : 894. http://dx.doi.org/10.3390/f11080894.
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Oaks are a dominant woody plant genus in the northern hemisphere that occupy a wide range of habitats and are ecologically diverse. We implemented a functional trait approach that included nine functional traits related to leaves and stems in order to explain the species coexistence of 21 oak species along a water availability gradient in a temperate forest in Mexico. This particular forest is characterized as a biodiversity hotspot, with many oak species including some endemics. Our main aim was to investigate whether the different oak species had specific trait associations that allow them to coexist along an environmental gradient at regional scale. First, we explored trait covariation and determined the main functional dimensions in which oaks were segregated. Second, we explored how environmental variation has selected for restricted functional dimensions that shape oak distributions along the gradient, regardless of their leaf life span or phylogeny (section level). Third, we quantified the niche overlap between the oak functional spaces at different levels. The analyzed species showed three functional dimensions of trait variation: a primary axis related to the leaf economic spectrum, which corresponds to the segregation of the species according to leaf habit; a second axis that reflects the stem hydraulic properties and corresponds to species segregation followed by phylogenetic segregation, reflecting some degree of trait conservatism, and a third axis, represented mainly by leaf area and plant height, that corresponds to species segregation. Finally, our findings indicated that the functional space measured with leaf traits and stem traits such as hydraulic capacity was integrally linked to niche differentiation. This linkage suggests that the earliest mechanism of species segregation was related to habitat suitability and that the stem hydraulic trade-off reflects differences between phylogenetic sections; these traits may promote coexistence between distantly related oak species.
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Kremer, Antoine. « Microevolution of European temperate oaks in response to environmental changes ». Comptes Rendus Biologies 339, no 7-8 (juillet 2016) : 263–67. http://dx.doi.org/10.1016/j.crvi.2016.04.014.
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Harayama, Hisanori, Atsushi Ishida et Jin Yoshimura. « Overwintering evergreen oaks reverse typical relationships between leaf traits in a species spectrum ». Royal Society Open Science 3, no 7 (juillet 2016) : 160276. http://dx.doi.org/10.1098/rsos.160276.
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The leaf economics spectrum has given us a fundamental understanding of the species variations in leaf variables. Across plant species, tight correlations among leaf mass per area (LMA), mass-based nitrogen ( N m ) and photosynthetic rate ( A m ) and leaf lifespan have been well known as trade-offs in leaf carbon economy. However, the regional or biome-level correlations may not be necessary to correspond with the global-scale analysis. Here, we show that almost all leaf variables in overwintering evergreen oaks in Japan were relatively well included within the evergreen-broadleaved trees in worldwide temperate forests, but N m was more consistent with that in deciduous broadleaved trees. Contrary to the universal correlations, the correlation between A m and N m among the evergreen oaks was negative and the correlation between A m and LMA disappeared. The unique performance was due to specific nitrogen allocation within leaves, i.e. the evergreen oaks with later leaf maturation had lower N m but higher nitrogen allocation to photosynthetic enzymes within leaves, to enhance carbon gain against the delayed leaf maturation and the shortened photosynthetic period due to cold winters. Our data demonstrate that correlations between leaf variables in a local scale are occasionally different from averaged global-scale datasets, because of the constraints in each biome.
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Löf, Magnus, Julien Barrere, Mattias Engman, Linda K. Petersson et Adrian Villalobos. « The influence of fencing on seedling establishment during reforestation of oak stands : a comparison of artificial and natural regeneration techniques including costs ». European Journal of Forest Research 140, no 4 (1 mars 2021) : 807–17. http://dx.doi.org/10.1007/s10342-021-01369-w.
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AbstractIn temperate Europe, oak-dominated forests are widespread, supporting high biodiversity and providing important ecosystem services. Insufficient natural regeneration has, however, been a concern for over a century. The objective of this study was to gain insights into differences in regeneration success using artificial and natural regeneration techniques for reforestation of oak (Quercus robur L.) stands. We monitored seedlings following planting, direct seeding and natural regeneration over five years in a randomized block experiment in southern Sweden with fenced and non-fenced plots. Fencing had a strong positive effect on height growth, especially for planted seedlings that were taller than the other seedlings and more frequently browsed in non-fenced plots. In contrast, there was little effect of fencing on survival, establishment rate and recruitment rate of seedlings. Due to aboveground damage on seedlings from voles, protection of acorns did not improve establishment rate following direct seeding. Under current circumstances at the site with a sparse shelterwood of old oaks, we conclude that natural regeneration was the most cost-efficient regeneration method. It resulted in the most seedlings at the lowest cost. However, regeneration success was heavily influenced by interference from herbaceous vegetation. With a small additional investment in vegetation control, the results might have been improved for planting and direct seeding.
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Canelo, Tara, Álvaro Gaytán, Carlos Pérez-Izquierdo et Raúl Bonal. « Effects of Longer Droughts on Holm Oak Quercus ilex L. Acorn Pests : Consequences for Infestation Rates, Seed Biomass and Embryo Survival ». Diversity 13, no 3 (5 mars 2021) : 110. http://dx.doi.org/10.3390/d13030110.
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The effects of climate change on oaks Quercus spp. constitute a main environmental concern for the conservation of temperate forests. In this context, we assessed the consequences of longer droughts on the interactions between the holm oak Quercus ilex L. and its main acorn pests. Infested acorns were prematurely abscised before reaching their potential size. The volume of the acorns attacked by Cydia fagiglandana (Lepidoptera) was smaller than those attacked by Curculio elephas (Coleoptera); however, their weight did not differ because Curculio larvae consumed more cotyledon. For the same reason, embryo survival likelihood was not lower in Cydia acorns despite their smaller size. Delays of late summer rain reduced infestation by Curculio, as soil hardness hampers adult emergence from their underground cells. By contrast, late and scarce precipitations benefited Cydia; rainfall might hamper adult flight and eggs/L1 larvae survival. There was not a “zero-sum” effect, because the decrease of Curculio infestation rates was not fully compensated by an increase of Cydia. Under the longer droughts projected for the Mediterranean Basin, our results predict lower infestation rates and higher acorn survival likelihood. However, further studies including other environmental factors are needed to better forecast the net consequences for holm oak fitness.
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Sork, V. L. « Evolutionary ecology of mast-seeding in temperate and tropical oaks (Quercus spp.) ». Vegetatio 107-108, no 1 (juin 1993) : 133–47. http://dx.doi.org/10.1007/bf00052217.
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Taylor, Benton N., Angelica E. Patterson, Moyosore Ajayi, Rachel Arkebauer, Karen Bao, Natalie Bray, Robert M. Elliott et al. « Growth and physiology of a dominant understory shrub, Hamamelis virginiana, following canopy disturbance in a temperate hardwood forest ». Canadian Journal of Forest Research 47, no 2 (février 2017) : 193–202. http://dx.doi.org/10.1139/cjfr-2016-0208.
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As global climatic changes increase plant susceptibility to large-scale disturbances such as drought and pathogens, understory responses to these disturbances will become increasingly important to long-term forest dynamics. To better understand understory responses to canopy disturbance, we measured changes in the growth and physiology of the dominant understory shrub, American witch-hazel (Hamamelis virginiana L.), in response to girdling of canopy oaks in a temperate hardwood forest of the northeastern United States. Changes in the growth and physiology of H. virginiana may be important to the regeneration of northeastern temperate forests, as this common shrub largely shapes the microenvironment for seedlings on the forest floor where it occurs. Canopy disturbance by girdling resulted in significant increases in light and soil nitrogen availability. In response to these environmental changes, basal-area growth of H. virginiana increased by an average 334%. This growth increase corresponded to significant increases in foliar nitrogen, respiration, and leaf chlorophyll and carotenoid concentrations. These findings indicate improved environmental conditions and increased growth for this understory shrub following the loss of dominant canopy trees. This study suggests that following large-scale canopy disturbance, H. virginiana and shrubs like it may play an important role in competing for soil N and shading seedlings of regenerating canopy species.
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Quick, Susan E., Giulio Curioni, Nicholas J. Harper, Stefan Krause et A. Robert MacKenzie. « Water usage of old-growth oak at elevated CO2 in the FACE (Free-Air CO2 Enrichment) of climate change ». Biogeosciences 22, no 6 (25 mars 2025) : 1557–81. https://doi.org/10.5194/bg-22-1557-2025.
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Abstract. Predicting how increased atmospheric CO2 levels will affect water usage by whole, mature trees remains a challenge. The present study investigates diurnal (i.e. daylight) water usage of oaks within an old-growth forest during an experimental treatment season (April–October, inclusive). Over the years 2017–2021, inclusive (years 1–5 of the experiment), we collected individual tree data from 18 oaks (Quercus robur L.) within a large-scale manipulative experiment at the Birmingham Institute of Forest Research (BIFoR) Free-Air CO2 Enrichment (FACE) temperate forest in central England, UK. Diurnal tree water usage per day (TWU, L d−1) across the leaf-on seasons was derived from these data. Equal tree numbers were monitored in each treatment: FACE infrastructure arrays (+150 µ mol mol−1) of elevated CO2 (eCO2), FACE infrastructure control ambient CO2 (aCO2) arrays, and control “ghost” (no-treatment, no-infrastructure) arrays. TWU was linearly proportional to tree stem radius, Rb (∼ 3.1 L d−1 mm−1; 274 mm ≤ Rb ≤ 465 mm). Rb was also a very good proxy for projected canopy area, Ac (m2), which was linearly proportional to Rb (∼ 617 m2 m−1). Applying the stem-to-canopy relation implied a mean July water usage of ∼ 5 L d−1 m−2 of projected oak canopy in the BIFoR FACE forest. We normalised TWU by individual tree Rb to derive TWUn (L d−1 mm−1). We report whole-season treatment effects, differing year on year, alongside July-only results. In the 2019 and 2021 seasons, after correction for repeated measures, there was a 13 %–16 %, reduction in eCO2 TWUn compared to aCO2 TWUn, with a marginal 4 % reduction in 2020, but these model results were not statistically significant. Control trees exhibited a significant 27 % increase in aCO2 TWUn compared to ghost TWUn in the whole season in 2019, with lesser, nonsignificant fixed effects in 2020 and 2021. Several factors may have contributed: the installation or operation of FACE infrastructure; array-specific differences in soil moisture, slope, or soil respiration; or the mix of subdominant tree species present. Our results showing normalised per-tree water savings under eCO2 align with sap flow results from other FACE experiments and greatly extend the duration of observations for oak, elucidating seasonal patterns and interannual differences. Our tree-centred viewpoint complements leaf-level and ground-based measurements to extend our understanding of plant water usage in an old-growth oak forest.
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Nordén, Björn, Frank Götmark, Martin Ryberg, Heidi Paltto et Johan Allmér. « Partial cutting reduces species richness of fungi on woody debris in oak-rich forests ». Canadian Journal of Forest Research 38, no 7 (juillet 2008) : 1807–16. http://dx.doi.org/10.1139/x08-031.
Texte intégralRésumé :
Partial cutting is increasingly applied in European temperate oak-dominated forests for biofuel harvesting, and to counteract succession in protected stands. Effects on biodiversity of these measures need to be carefully evaluated, and species-rich but neglected taxa such as fungi should be considered. We studied the effects of partial cutting on fungal fruiting bodies on woody debris. In 21 closed canopy forests rich in large oaks in Sweden, on average 25%–30% of the basal area was cut. Fruiting bodies were counted and some were collected in treated and control plots before and after treatment. We found 334 basidiomycete and 47 ascomycete species. Species richness of basidiomycetes declined significantly more in treated plots (on average 26%) than in control plots (on average 13%) between seasons. Species richness of ascomycetes increased by 17% in control plots and decreased by 2% in treated plots. Total species richness was significantly reduced on fine woody debris (1–10 cm in diameter), but not on coarse woody debris (>10 cm). Overall species composition did not change significantly as a result of partial cutting, but red-listed species tended to decrease more in treated plots. We suggest that approximately 30% of the stands should not be thinned, and dead stems and fallen branches should not be removed, to favor saproxylic fungi and their associated fauna.
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JGENTI, Lali, Gia BOLKVADZE, Maradi IAKOBADZE et Inga DIASAMIDZE. « Flora and Fauna Conservation in Machakhela National Park Georgia ». Eurasia Proceedings of Health, Environment and Life Sciences 5 (2 novembre 2022) : 35–39. http://dx.doi.org/10.55549/ephels.32.
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Biodiversity conservation is the protection and management of biodiversity to obtain resources for sustainable development. The diverse topography and climate has provided conditions to develop a remarkably wide array of landscapes and plant formations. They include two features of plants and plant associations that date back millions of years: the Colchic refugium in the eastern Black Sea basin and the Hyrcanic region on the southern Caspian Sea coast. These “refugia”/refugial forests harbour many locally endemic plants - species that are found nowhere else. They include relict and endemic oaks (such as Quercus imeretina, Q. hartwissiana), Medvedev’s birch (Betula medwedewii), Ungern’s and Smirow’s rhododendrons (Rhododendron ungernii, R. smirnowii) in the Colchic. Machakhela National Park is located 30 km away from Batumi in the foothills of the Lesser Caucasus. Close to the Turkish border, Machakhela expands the protection of the unique ecosystems of the Colchic forests – rich tropical and sub-tropical habitats (temperate rain forests with peat bogs) which contain unrivaled biodiversity, and are rich in relics of the tertiary period: Colchic bot box, chestnut, nut, hazel-nut, and bot trees abound. Trails are being developed and since this park has only been recently established, you can still be one of the first to witness its wet beauty. At the same time these unique forests can mostly be classified as temperate rainforests, due to the same principal reasons as for other temperate rainforest regions: relevant slopes of barriermountains located along coastlines that trap a large portion of the humidity from sea air masses. Montane barriers also contribute to a warm and humid climate that has been present since the late Tertiary and is the primary reason that the Caucasus has acted as a shelter for humid- and warm-requiring (hygro-thermophilous) relicts during the ice age.
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Gennaro, M., P. Gonthier, G. Nicolotti et G. P. Cellerino. « First Report of Tubakia dryina in Buds and Shoots of Quercus cerris and Quercus robur ». Plant Disease 85, no 12 (décembre 2001) : 1289. http://dx.doi.org/10.1094/pdis.2001.85.12.1289b.
Texte intégralRésumé :
Tubakia dryina (Sacc.) Sutt. (teleomorph Dicarpella dryina Belisario & Barr) is a widespread leaf pathogen in northern temperate zones and is mainly associated with Quercus spp. During 2000, T. dryina was isolated from seasonal samplings of endophytic fungal communities of Turkey (Q. cerris L.) and English (Q. robur L.) oaks. Samples were taken from healthy and declining trees showing no symptoms of T. dryina in a coppice with saplings in Piedmont (northwestern Italy). Fragments of freshly opened buds (1-year-old shoots) and leaves were surface-sterilized by immersion in 75% ethanol for 1 min, in a NaClO solution (3 to 4% active ingredient) for 3 min, and in 75% ethanol for 30 s, then plated on potato dextrose agar. T. dryina was found in all sampled tissues. Its frequency in buds was higher in healthy trees than in declining trees (≈25 versus 12%; analysis of variance test P < 0.05), whereas no difference was found in shoots. T. dryina was also isolated from asymptomatic leaves, but more often from declining trees than from healthy ones (≈40 versus 10%; P < 0.05). No differences were observed when comparing the two oak species. The fungus was previously reported in buds of Q. nigra L. in North America (2), and it has also been isolated from symptomatic leaves of Q. cerris in a 5-year-old plantation (1). T. dryina was found in other studies in leaves and dead twigs of Q. robur. To our knowledge, this is the first report of T. dryina in buds and shoots of European oak species, suggesting an important role of this fungus as either an endophyte or a latent pathogen associated with oak decline. References: (1) A. Belisario. Plant Dis. 77:647, 1993. (2) Y. C. Zhang and J. T. Walker. Plant Dis. 79:568, 1995.
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Santos, Mónica, Helder Fraga, Margarida Belo-Pereira et João A. Santos. « Assessment of Growing Thermal Conditions of Main Fruit Species in Portugal Based on Hourly Records from a Weather Station Network ». Applied Sciences 9, no 18 (10 septembre 2019) : 3782. http://dx.doi.org/10.3390/app9183782.
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Thermal conditions in mainland Portugal were evaluated using a new hourly database over the recent period of 2000–2018 (19 years). The number of hours within each different temperature interval was calculated from the long-term means of the hourly temperatures of a network of 63 meteorological stations. A geostatistical approach, using elevation, distance to coastline and latitude, was subsequently applied to provide gridded patterns at a high spatial resolution (1 km grid spacing). Eight fruit species (almond tree, carob tree, chestnut tree, citrus fruits, cork oaks, holm oaks, olive trees, and grapevines) were selected to assess their hourly thermal growing conditions. The results highlight the strong spatial variability of temperature levels in mainland Portugal, providing new insights into their spatial distribution. The number of hours in the year with cool conditions (4–12 °C) is higher in the northern-central regions, mainly in mountainous areas. Additionally, the number of hours in the year with temperate conditions (12–20 °C) emphasizes the importance of the distance to the coastline (maritime influence). The warm conditions (20–28 °C) are most prevalent in the south of the country and in the Douro valley, whereas the very warm conditions (number of hours with temperature between 28–36 °C) are essentially restricted to inner-southern Portugal and to the upper Douro valley. This study also reveals, with high accuracy, the thermal growing conditions of main fruit species in mainland Portugal, giving particular emphasis to olive trees and grapevines. These findings may help decision support systems providing more reliable and accurate guidelines to stakeholders, decision-makers, and farmers. The main maps are available in a widely used file format (shapefile), thus allowing their application to a wide range of other areas of interest.
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Morales-Saldaña, Saddan, Oscar Angel De Luna-Bonilla, Yareli Joselin Cadena-Rodríguez et Susana Valencia-A. « Species distribution of Quercus (Fagaceae) along an altitude gradient, reveals zonation in a hotspot ». Botanical Sciences 99, no 4 (22 juillet 2021) : 722–34. http://dx.doi.org/10.17129/botsci.2761.
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Background: The genus Quercus has a keystone role in the temperate forests in the northern hemisphere; thus this offers an interesting opportunity to use it as a model to know altitudinal species richness patterns which could be used in further studies and projects in biodiversity conservation.
Questions: It is possible to detect an altitudinal gradient based on the genus Quercus distribution? What climatic variables are most important in the altitudinal distribution of the genus Quercus?
Study site: The physiographic province of Sierra Madre del Sur (SMS) located southwest of Mexico.
Methods: Based on 3,267 herbarium registers of 61 species, a data matrix was created with the presence/absence of each species in altitudinal intervals of 100 m. Then a similarity matrix was obtained using the Sorensen-Dice index in the R software. Through a discriminant analysis, we evaluated for environmental differences among the altitudinal zones previously obtained through a cluster analysis.
Results: We found three altitudinal zones, each one defined by exclusive species, and two important species turnover points. The species richness distribution showed a hump-shaped pattern along the altitudinal gradient. The overall model was highly significant, evidencing the existence of different temperature and precipitation regimes throughout the altitudinal distribution of oaks species in SMS.
Conclusions: The altitudinal distribution of oak species in the SMS is not homogeneous and is restricted mainly due to differences in the precipitation and temperature regimes. The altitudinal distribution pattern found in this study could be explained considering ecological and historical factors.
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Hernández-Calderón, Erasto, Antonio González-Rodríguez, Rodrigo Méndez-Alonzo, Ernesto Vega-Peña et Ken Oyama. « Contrasting leaf phenology in two white oaks, Quercus magnoliifolia and Quercus resinosa, along an altitudinal gradient in Mexico ». Canadian Journal of Forest Research 43, no 2 (février 2013) : 208–13. http://dx.doi.org/10.1139/cjfr-2012-0406.
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In tropical latitudes, the analysis of leaf phenology in tree species of lineages with temperate origin can help better understanding the potential effects of climate change on these forests. Over three years (2008–2010), we recorded the timing of bud burst (BB), leaf unfolding (LU), and leaf spreading (LS) and their relation to temperature, precipitation, and soil water potential in two deciduous oak species (Quercus magnoliifolia Née and Quercus resinosa Liebm.) along an altitudinal gradient at the Tequila Volcano, central Mexico. Quercus magnoliifolia was monitored at three altitudes, 1450, 1667, and 1787 m, and Q. resinosa was monitored at 1787, 2055, and 2110 m. The onset of BB, LU, and LS occurred earlier at lower elevations with higher temperature in Q. magnoliifolia, but in Q. resinosa only the onset of BB occurred later at lower elevations with higher temperature. BB, LU, and LS were not correlated with rainfall and soil water potential in the two species. The total duration time of leaf development was not significantly correlated with rainfall in Q. magnoliifolia, but a significant negative correlation with rainfall was found in Q. resinosa. Results indicated that leaf phenology of the two examined oak species exhibited contrasting responses to temperature and precipitation.
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Valencia-A., Susana, Gabriel Flores-Franco, Jaime Jiménez-Ramírez et Mauricio Mora-Jarvio. « Distribution and diversity of Fagaceae in Hidalgo, Mexico ». Botanical Sciences 95, no 4 (19 décembre 2017) : 660. http://dx.doi.org/10.17129/botsci.1020.
Texte intégralRésumé :
<p><strong>Background:</strong> The family Fagaceae is one of the most important in temperate regions of the Northern hemisphere. <em>Fagus</em> and <em>Quercus</em> are distributed in Mexico, the former in Northeastern Mexico, while the latter reaches a high diversity in the Sierra Madre Oriental, Mexico. In Hidalgo state, located mainly in the Sierra Madre Oriental, knowledge of the Fagaceae diversity is still uncertain.<em></em></p><p><strong>Questions and/or hypothesis:</strong> We carried out a taxonomic revision of the genus and species of Fagaceae in Hidalgo state. We determined how many and which species are distributed in Hidalgo. We also present a morphological description and ecological characters of each one.</p><p><strong>Studied species:</strong> The species of the family Fagaceae</p><p><strong>Study site:</strong> Hidalgo state, Mexico.</p><p><strong>Method:</strong> We collected herbarium specimens, made field observations and reviewed herbarium data of Fagaceae specimens at FCME, INEGI, MEXU, ENCB, SLPM, HUMO, XAL and partly BH herbaria. In addition, we checked taxonomic literature and protologues of each species.</p><p><strong>Results: </strong>We found one species of <em>Fagus</em> and 43 of <em>Quercus</em>, 22 of which belong to the section <em>Quercus</em> (white oaks) and 21 to section <em>Lobatae</em> (red oaks). Morphological descriptions, altitudinal and geographical distribution, vegetation types of each species and a dichotomous key for species identification are presented. Illustrations and photographs of the species are also included.</p><p><strong>Conclusions:</strong> A high diversity of Fagaceae species is present in Hidalgo state. In Mexico, Hidalgo ranks in fifth place for oak species diversity, just behind Oaxaca (50 species), Puebla (50), San Luis Potosí (45), and Jalisco (45).<strong></strong></p>
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Degen, Bernd, Yulai Yanbaev, Malte Mader, Ruslan Ianbaev, Svetlana Bakhtina, Hilke Schroeder et Celine Blanc-Jolivet. « Impact of Gene Flow and Introgression on the Range Wide Genetic Structure of Quercus robur (L.) in Europe ». Forests 12, no 10 (19 octobre 2021) : 1425. http://dx.doi.org/10.3390/f12101425.
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As for most other temperate broadleaved tree species, large-scale genetic inventories of pedunculate oak (Quercus robur L.) have focused on the plastidial genome, which showed the impact of post-glacial recolonization and manmade seed transfer. However, how have pollen mediated gene flow and introgression impacted the large-scale genetic structure? To answer these questions, we did a genetic inventory on 1970 pedunculate oak trees from 197 locations in 13 European countries. All samples were screened with a targeted sequencing approach on a set of 381 polymorphic loci (356 nuclear SNPs, 3 nuclear InDels, 17 chloroplast SNPs, and 5 mitochondrial SNPs). In a former analysis with additional 1763 putative Quercus petraea trees screened for the same gene markers we obtained estimates on the species admixture of all pedunculate oak trees. We identified 13 plastidial haplotypes, which showed a strong spatial pattern with a highly significant autocorrelation up to a range of 1250 km. Significant spatial genetic structure up to 1250 km was also observed at the nuclear loci. However, the differentiation at the nuclear gene markers was much lower compared to the organelle gene markers. The matrix of genetic distances among locations was partially correlated between nuclear and organelle genomes. Bayesian clustering analysis revealed the best fit to the data for a sub-division into two gene pools. One gene pool is dominating the west and the other is the most abundant in the east. The western gene pool was significantly influenced by introgression from Quercus petraea in the past. In Germany, we identified a contact zone of pedunculate oaks with different introgression intensity, likely resulting from different historical levels of introgression in glacial refugia or during postglacial recolonization. The main directions of postglacial recolonization were south to north and south to northwest in West and Central Europe, and for the eastern haplotypes also east to west in Central Europe. By contrast, the pollen mediated gene flow and introgression from Q. petraea modified the large-scale structure at the nuclear gene markers with significant west–east direction.
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Broughton, Richard K., James M. Bullock, Charles George, Ross A. Hill, Shelley A. Hinsley, Marta Maziarz, Markus Melin, J. Owen Mountford, Tim H. Sparks et Richard F. Pywell. « Long-term woodland restoration on lowland farmland through passive rewilding ». PLOS ONE 16, no 6 (16 juin 2021) : e0252466. http://dx.doi.org/10.1371/journal.pone.0252466.
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Natural succession of vegetation on abandoned farmland provides opportunities for passive rewilding to re-establish native woodlands, but in Western Europe the patterns and outcomes of vegetation colonisation are poorly known. We combine time series of field surveys and remote sensing (lidar and photogrammetry) to study woodland development on two farmland fields in England over 24 and 59 years respectively: the New Wilderness (2.1 ha) abandoned in 1996, and the Old Wilderness (3.9 ha) abandoned in 1961, both adjacent to ancient woodland. Woody vegetation colonisation of the New Wilderness was rapid, with 86% vegetation cover averaging 2.9 m tall after 23 years post-abandonment. The Old Wilderness had 100% woody cover averaging 13.1 m tall after 53 years, with an overstorey tree-canopy (≥ 8 m tall) covering 91%. By this stage, the structural characteristics of the Old Wilderness were approaching those of neighbouring ancient woodlands. The woody species composition of both Wildernesses differed from ancient woodland, being dominated by animal-dispersed pedunculate oak Quercus robur and berry-bearing shrubs. Tree colonisation was spatially clustered, with wind-dispersed common ash Fraxinus excelsior mostly occurring near seed sources in adjacent woodland and hedgerows, and clusters of oaks probably resulting from acorn hoarding by birds and rodents. After 24 years the density of live trees in the New Wilderness was 132/ha (57% oak), with 390/ha (52% oak) in the Old Wilderness after 59 years; deadwood accounted for 8% of tree stems in the former and 14% in the latter. Passive rewilding of these ‘Wilderness’ sites shows that closed-canopy woodland readily re-established on abandoned farmland close to existing woodland, it was resilient to the presence of herbivores and variable weather, and approached the height structure of older woods within approximately 50 years. This study provides valuable long-term reference data in temperate Europe, helping to inform predictions of the potential outcomes of widespread abandonment of agricultural land in this region.
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Deniau, Maud, Mickael Pihain, Benoît Béchade, Vincent Jung, Margot Brunellière, Valérie Gouesbet et Andreas Prinzing. « Seeds and seedlings of oaks suffer from mammals and molluscs close to phylogenetically isolated, old adults ». Annals of Botany 127, no 6 (28 janvier 2021) : 787–98. http://dx.doi.org/10.1093/aob/mcab010.
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Abstract Background and Aims Mammals and molluscs (MaM) are abundant herbivores of tree seeds and seedlings, but how the trees and their environment affect MaM herbivory has been little studied. MaM tend to move much larger distances during the feeding stage than the more frequently studied insect herbivores. We hypothesize that MaM (1) select and stay within the patches that promise to be relatively the richest in seeds and seedlings, i.e. patches around adult trees that are old and within a distantly related, less productive neighborhood; and (2) try to remain sheltered from predators while foraging, i.e. mammals remain close to adult trees or to cover by herbs while foraging, and might force their mollusc prey to show the opposite distribution. Methods We exposed oak acorns and seedlings in a temperate forest along transects from adult conspecifics in different neighbourhoods. We followed acorn removal and leaf herbivory. We used exclusion experiments to separate acorn removal by ungulates vs. rodents and leaf herbivory by insects vs. molluscs. We measured the size of the closest conspecific adult tree, its phylogenetic isolation from the neighbourhood and the herbaceous ground cover. Key Results Consistent with our hypothesis, rodents removed seeds around adult trees surrounded by phylogenetically distant trees and by a dense herb cover. Molluscs grazed seedlings surrounding large conspecific adults and where herb cover is scarce. Contrary to our hypothesis, the impact of MaM did not change from 1 to 5 m distance from adult trees. Conclusions We suggest that foraging decisions of MaM repulse seedlings from old adults, and mediate the negative effects of herbaceous vegetation on tree recruitment. Also, an increase in mammalian seed predation might prevent trees from establishing in the niches of phylogenetically distantly related species, contrary to what is known from insect enemies.
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Cavender-Bares, Jeannine, Antonio Gonzalez-Rodriguez, Annette Pahlich, Kari Koehler et Nicholas Deacon. « Phylogeography and climatic niche evolution in live oaks (Quercus series Virentes) from the tropics to the temperate zone ». Journal of Biogeography 38, no 5 (31 janvier 2011) : 962–81. http://dx.doi.org/10.1111/j.1365-2699.2010.02451.x.
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Ryabukha, Anna, et Pyotr Kuzmin. « Genotyping of Quercus robur L. ecotypes of the bayrachny oak forest of the Ergeninsky upland based on polymorphism of ISSR markers ». Sustainable Development of Mountain Territories 16, no 4 (30 décembre 2024) : 1756–65. https://doi.org/10.21177/1998-4502-2024-16-4-1756-1765.
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Introduction. The Volgograd Region is a sparsely wooded region, forests on its territory occupy 4.3% of the total territory, therefore, afforestation and combating various types of erosion are especially important here. The Chapurnikovskaya gully, adjacent to the Ergeninskaya upland, is home to the largest natural oak forest in the south of the Volgograd agglomeration. The study of the genetic and physiological-biochomic features of the unique oaks growing in it, some of which have reached the age of 200 years, will help identify ecotypes and individuals resistant to various types of stress and use them for afforestation in extreme forest conditions. The purpose of this study was the molecular genetics and physiological-biochemical analysis of the upland, slope and tall oak ecotypes from the Chapurnikovskaya gully. Materials and methods. ISSR markers and ITS marker were used for molecular genetic analysis of three ecotypes of Quercus robur L. of the bayrachny oak grove of the Ergeninsky upland. The physiological and biochemical analysis of pigments and phenolic compounds was carried out by spectrophotometry. Results and discussion. As a result of the molecular genetic analysis, a set of DNA fragments was obtained, the number and size of which (polymorphism) were different for different oak genotypes. The highest percentage of polymorphism of ISSR markers was established using primers UBC 811, UBC 826, UBC 835 and UBC 841. These primers with ITS primer were also used for the molecular genetic identification of ecotypes, the calculated polymorphism was 43.84% for the upland ecotype, 37% for the slope, and 56.16% for the tallow. The ratio of chlorophylls a and b significantly differed in the three ecotypes, being the highest for the tallow. The ratio (Cla+Clb)/Car was highest in the slope ecotype (42.09±22.31), exceeding by 50% the corresponding ratio for the tallow and by 39% for the upland ecotypes. The leaves of the upland ecotype contain the largest amount of phenols (26.69±5.79 mg/g), which are important protective barriers against adverse environmental factors. Conclusions. The upland oak ecotype, which grows on the upper slopes of the beam, is most resistant to arid conditions and can be recommended for fixing and terracing mountain slopes, creating forest belts on hilly terrain in arid conditions. Samples of the talvezhny oak ecotype with a higher level of polymorphism can be proposed for afforestation in temperate conditions on alluvial soils and for urban landscaping.
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Pérez-de-Lis, Gonzalo, Ignacio García-González, Vicente Rozas et José Miguel Olano. « Feedbacks between earlywood anatomy and non-structural carbohydrates affect spring phenology and wood production in ring-porous oaks ». Biogeosciences 13, no 19 (5 octobre 2016) : 5499–510. http://dx.doi.org/10.5194/bg-13-5499-2016.
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Abstract. Non-structural carbohydrates (NSC) play a central role in the construction and maintenance of a tree's vascular system, but feedbacks between the NSC status of trees and wood formation are not fully understood. We aimed to evaluate multiple dependencies among wood anatomy, winter NSC, and phenology for coexisting temperate (Quercus robur) and sub-Mediterranean (Q. pyrenaica) oaks along a water-availability gradient in the NW Iberian Peninsula. Sapwood NSC concentrations were quantified at three sites in December 2012 (N = 240). Leaf phenology and wood anatomy were surveyed in 2013. Structural equation modelling was used to analyse the interplay among hydraulic diameter (Dh), winter NSC, budburst date, and earlywood vessel production (EVP), while the effect of Dh and EVP on latewood width was assessed by using a mixed-effects model. NSC and wood production increased under drier conditions for both species. Q. robur showed a narrower Dh and lower soluble sugar (SS) concentration (3.88–5.08 % dry matter) than Q. pyrenaica (4.06–5.57 % dry matter), but Q. robur exhibited larger EVP and wider latewood (1403 µm) than Q. pyrenaica (667 µm). Stem diameter and Dh had a positive effect on SS concentrations, which were related to an earlier leaf flushing in both species. Sapwood sugar content appeared to limit EVP exclusively in Q. pyrenaica. In turn, Dh and EVP were found to be key predictors of latewood growth. Our results confirm that sapwood SS concentrations are involved in modulating growth resumption and xylem production in spring. Q. pyrenaica exhibited a tighter control of carbohydrate allocation to wood formation than Q. robur, which would play a role in protecting against environmental stress in the sub-Mediterranean area.
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Zidianakis G., Zidianakis G., G. Iliopoulos et C. Fassoulas. « A NEW LATE MIOCENE PLANT ASSEMBLAGE FROM MESSARA BASIN (CRETE, GREECE) ». Bulletin of the Geological Society of Greece 43, no 2 (23 janvier 2017) : 781. http://dx.doi.org/10.12681/bgsg.11244.
Texte intégralRésumé :
A rich terrigenous plant assemblage was recently excavated from early Tortonian deposits at Messara basin, southern Crete. The macro-remains are perfectly preserved as impressions or carbonized compressions in poorly lithified and locally laminated, blue-green clays with an age of at least 10.5 Ma and thus can be considered as the oldest plant assemblage found in Crete todate. Gymnosperms are represented by the families of Pinaceae (pine needles and winged seeds), Cupressaceae and Taxodiaceae (leafy twings of Taxodium). Besides, 19 different angiosperm taxa of trees and shrubs have been also determined. Fagaceae is the most diversified with foliage of beech and several deciduous and evergreen oaks, while Myricaceae contribute mainly as abundant leaf remains of Myrica lignitum. Accessory elements of evergreen Lauraceae (Daphnogene polymorpha), sclerophyllus shrubs of Buxaceae (Buxus pliocenica) and various deciduous dicotyledonous such as Populus crenata, Liquidambar europaea, Carya minor and Acer pseudomonspessulanum are well documented. Leguminosae is recorded by a significant number of various small leaflet imprints. Therefore, the recovered remains indicate swampy forest habitats dominated by hygrophilic woody plants of Taxodium and Myrica, while in the surrounding plains and slopes a mixed mesophytic forest with a relatively low proportion of evergreen plants occurred in early-Late Miocene times in Crete depicting a moderately humid, warm-temperate nature for the climate.
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Grueter, Cyril C., Dayong Li, Baoping Ren, Zuofu Xiang et Ming Li. « Food Abundance Is the Main Determinant of High-Altitude Range Use in Snub-Nosed Monkeys ». International Journal of Zoology 2012 (2012) : 1–4. http://dx.doi.org/10.1155/2012/739419.
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High-altitude dwelling primates have to optimize navigating a space that contains both a vertical and horizontal component. Black-and-white or Yunnan snub-nosed monkeys (Rhinopithecus bieti) are extreme by primate standards in inhabiting relatively cold subalpine temperate forests at very high altitudes where large seasonal variation in climate and food availability is expected to profoundly modulate their ranging strategies so as to ensure a positive energy balance. A “semi-nomadic” group ofR. bietiwas followed for 20 months in the montane Samage Forest, Baimaxueshan Nature Reserve, Yunnan, PRC, which consisted of evergreen conifers, oaks, and deciduous broadleaf trees. The aim of this study was to disentangle the effects of climate and phenology on patterns of altitudinal range use. Altitude used by the group ranged from a maximum of 3550 m in July 2007 to a minimum of 3060 m in April 2006. The proportional use of lichen, the monkeys’ staple fallback food, in the diet explained more variation in monthly use of altitudes than climatic factors and availability of flush and fruit. The abundance of lichens at high altitudes, the lack of alternative foods in winter, and the need to satisfy the monkey's basal energetic requirements explain the effect of lichenivory on use of altitudes.
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Böhm, Stefan M., Konstans Wells et Elisabeth K. V. Kalko. « Top-Down Control of Herbivory by Birds and Bats in the Canopy of Temperate Broad-Leaved Oaks (Quercus robur) ». PLoS ONE 6, no 4 (4 avril 2011) : e17857. http://dx.doi.org/10.1371/journal.pone.0017857.
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Duan, Shengwu, Hong S. He, Lauren S. Pile Knapp, Thomas W. Bonnot et Jacob S. Fraser. « Private land management is more important than public land in sustaining oaks in temperate forests in the eastern U.S. » Journal of Environmental Management 352 (février 2024) : 120013. http://dx.doi.org/10.1016/j.jenvman.2023.120013.
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Journé, Valentin, Thomas Caignard, Andrew Hacket-Pain et Michał Bogdziewicz. « Leaf phenology correlates with fruit production in European beech (Fagus sylvatica) and in temperate oaks (Quercus robur and Quercus petraea) ». European Journal of Forest Research 140, no 3 (15 février 2021) : 733–44. http://dx.doi.org/10.1007/s10342-021-01363-2.
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Affek, Andrzej N., Edyta Regulska, Ewa Kołaczkowska, Anna Kowalska et Katarzyna Affek. « Pollination Potential of Riparian Hardwood Forests—A Multifaceted Field-Based Assessment in the Vistula Valley, Poland ». Forests 12, no 7 (12 juillet 2021) : 907. http://dx.doi.org/10.3390/f12070907.
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Riparian forests with oaks, ashes and elms, now highly fragmented and rare in Europe, are considered hotspots for ecosystem services. However, their capacity to provide pollination seems to be quite low, although reports from in-situ research supporting this view are scarce. Our goal was therefore to thoroughly assess their pollination potential based on multifaceted field measurements. For this, we selected six test sites with well-developed riparian hardwood forests, located in the agricultural landscape along the middle Vistula River in Poland. We used seven indicators relating to habitat suitability (nesting sites and floral resources) and pollinator abundance (bumblebees and other Apoidea) and propose a threshold value (AdjMax) based on value distribution and Hampel’s test to indicate the level of pollination potential for this type of riparian forest. The obtained AdjMax for bumblebee density was 500 ind. ha−1, for Apoidea abundance—0.42 ind. day−1, while for nectar resources—200 kg ha−1. We demonstrate that the investigated small patches of the riparian hardwood forest have a higher pollination potential than reported earlier for riparian and other broadleaved temperate forests, but the indicators were inconsistent. As forest islands in the agricultural landscape, riparian hardwood forests play an important role in maintaining the diversity and abundance of wild pollinators, especially in early spring when there is still no food base available elsewhere.
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Chen, Yuheng, Yao Li et Lingfeng Mao. « Combining the Effects of Global Warming, Land Use Change and Dispersal Limitations to Predict the Future Distributions of East Asian Cerris Oaks (Quercus Section Cerris, Fagaceae) in China ». Forests 13, no 3 (22 février 2022) : 367. http://dx.doi.org/10.3390/f13030367.
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Species shift their ranges in response to climate change (CC). However, they may not be able to track optimal conditions as soon as possible, due to limited dispersal ability or habitat fragmentation, caused by land use and land cover change (LULC). This study aimed to explore the combined impacts of CC, LULC and dispersal limitations on the future range dynamics of Quercus acutissima Carruth., Q. variabilis Blume and Q. chenii Nakai, three dominant Cerris oak tree species in warm-temperate and subtropical deciduous forests of China. We used the Maximum Entropy (Maxent) algorithm to predict the suitable habitats for the years 2050 and 2070, under three representative concentration pathways (RCPs). Habitat fragmentation patterns were examined to assess the influence of LULC. Two migration scenarios (full- and partial-migration) were compared to evaluate the effect of dispersal limitations. We found that annual precipitation (AP), minimum temperature in the coldest month (MTCM) and temperature seasonality (TS) play a key role in determining the present distributions of Q. chenii, while AP, MTCM and annual mean temperature (AMT) contribute the most to the distribution models of Q. variabilis and Q. acutissima. For all the three species, LULC will increase the level of habitat fragmentation and lead to the loss of core areas, while limited dispersal ability will restrict the accessibility of future potentially suitable habitats. Under the scenarios of CC and LULC, the suitable areas of Q. chenii will decrease sharply, while those of Q. variabilis in South China will become unsuitable. Our findings highlight the importance of considering dispersal ability, as well as land use and land cover change, for modeling species’ range shifts in the face of global warming. Our study also provides vital information for guiding the management of East Asian Cerris oaks in China; Q. chenii should be listed as a species requiring priority protection, and the threatened habitats of Q. variabilis should be protected to buffer the impacts of CC and LULC.
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Sarvašová, Lenka, Peter Zach, Michal Parák, Miroslav Saniga et Ján Kulfan. « Infestation of Early- and Late-Flushing Trees by Spring Caterpillars : An Associational Effect of Neighbouring Trees ». Forests 12, no 9 (18 septembre 2021) : 1281. http://dx.doi.org/10.3390/f12091281.
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In temperate forests within Europe, early-flushing (EF) deciduous trees are often heavily infested by early spring leaf-eating Lepidoptera, while late-flushing (LF) trees are better protected in a phenological manner against such heavy infestations, as spring moth larvae begin to appear before their bud burst. The associational effects of EF trees on LF ones are only poorly known. We studied whether or not the infestation of LF trees by spring Lepidoptera can be affected by EF ones if they grow in the immediate vicinity. We compared spring assemblages of leaf-eating larvae of Lepidoptera on LF Quercus cerris L. with those on EF Q. pubescens Willd. in several microhabitats in Slovakia, Central Europe. Larvae were collected from mature and young trees. Mature trees sampled were growing: (1) in a closed-canopy forest; (2) in small groups; or (3) as a lone tree. Forest and tree groups are both constituted by oak species. Tree groups and lone trees were 20–50 m distant from forest edges. Young trees were growing (1) under mature Q. pubescens trees in a forest or (2) as a lone tree within forest gaps or near the edges. In the closed-canopy forest where LF trees (Q. cerris) were surrounded by EF ones (Q. pubescens), the caterpillars on mature LF trees were in abundance, almost as on mature EF ones. The species composition of larval assemblages on the two oak species was similar. In contrast, on small groups and on lone trees, the lepidopteran larvae were significantly less abundant on LF trees than EF ones. In the case of young trees, the abundance of larvae and their composition assemblages on both oaks were comparable in the forest. In the open habitat, LF trees were less infested by larvae than EF ones and the assemblages of moth larvae differed between the two. Our results reveal the effect (associational susceptibility) of EF trees on LF ones when growing in a close vicinity. It means that the phenological protection of LF trees may not be sufficient if they grow close to or are surrounded by EF ones.
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Samec, Pavel, Petra Rychtecká, Miroslav Zeman et Miloš Zapletal. « Environmental Effects among Differently Located and Fertile Sites on Forest Basal-Area Increment in Temperate Zone ». Forests 13, no 4 (8 avril 2022) : 588. http://dx.doi.org/10.3390/f13040588.
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Environmental properties differently influence the growth of forest tree species. The antagonistic effects of variable environmental properties classify the forest response according to various tree compositions among different sites. The division of the forest response was assessed in 52 stands arranged into 26 types of 13 site management populations (MPs) in 5 areas in the Czech Republic territory. The assessment was performed using time-series multiple regressions of basal-area increment from pure immature stands of Norway spruce (Picea abies), Scots pine (Pinus sylvestris), oaks (Quercus sp.), ash (Fraxinus excelsior) and willows (Salix sp.) dependent on the interpolated average temperatures, annual precipitation, atmospheric concentrations of SO2, NOx and O3 and soil properties over the period 1971–2008 at p < 0.05. Site MPs differentiated the forest response to a greater extent than tree species. The response of the forests was significantly distributed by means of the montane, upland and waterlogged sites. The multiple determination index (r2) ≥ 0.6 indicated an adaptable tree increment but an interval of r2 between 0.80–0.92 implied forest sensitivity to variability in environmental properties on non-waterlogged sites. The index r2 < 0.6 suggested a fluctuating forest increment that reflects environmental variability inconsistently. The fluctuating increment most affected the spruce and pine stands grown from upland to submontane locations. Montane spruce stands, as well as rock pines, appeared to be one of the most sensitive ones to environmental change. Floodplain forests seemed as adaptable to variable environmental properties.
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Koehler, Kari, Alyson Center et Jeannine Cavender-Bares. « Evidence for a freezing tolerance-growth rate trade-off in the live oaks (Quercus series Virentes) across the tropical-temperate divide ». New Phytologist 193, no 3 (15 décembre 2011) : 730–44. http://dx.doi.org/10.1111/j.1469-8137.2011.03992.x.
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Redick, Caleb H., et Douglass F. Jacobs. « Mitigation of Deer Herbivory in Temperate Hardwood Forest Regeneration : A Meta-Analysis of Research Literature ». Forests 11, no 11 (19 novembre 2020) : 1220. http://dx.doi.org/10.3390/f11111220.
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Ungulate herbivory poses global challenges to forest regeneration. Deer, in combination with other biotic and abiotic factors, threaten to shift forest composition away from palatable hardwoods, such as oaks (Quercus spp.), and cause regeneration failure in some cases. Many studies have assessed methods to reduce or manage browse, but comprehensive analyses of the relative effectiveness of these techniques among published experiments are lacking. We synthesized the literature describing the results of methods to reduce deer browsing impacts, and assessed the effectiveness of deer browse management methods in controlling damage to hardwood forest regeneration. Specifically, we systematically analyzed results from 99 studies that used repellents, physical barriers, lethal population control, timber harvests, facilitation by neighboring plants, or fertilizer to affect browse, survival, or height growth of hardwood seedlings. Across studies, browse was reduced (mean effect size and confidence intervals) with the following: Fencing −3.17 (CI: −4.00–−1.31), shelters −1.28 (CI: −2.02–−0.67), cages −1.48 (CI: −3.14–−0.62), facilitation from neighboring plants −0.58 (CI: −1.11–−0.13), repellents −0.45 (CI: −0.56–−0.21), hunting −0.99 (CI: −1.51–−0.26). These methods each had positive effects on seedling height growth (except for repellents), and cages, timber harvests, fences, and mesh sleeves had positive effects on survival. Logging slash had no effect on browse incidence (−0.05, CI: −0.97–0.19). Fertilizer applied during seedling establishment increased browse (0.13, CI: 0.11–0.21), and did not affect height growth. We conclude that fences or other physical barriers best control for the effects of deer, but facilitation by surrounding vegetation, logging slash, hunting, habitat management through timber harvest, and certain repellents may also be moderately effective. Discrepancies between browse effectiveness and relative costs suggest that economic analyses should be developed to help to guide prescriptions for management.
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Frelich, Lee E., Peter B. Reich et David W. Peterson. « The changing role of fire in mediating the relationships among oaks, grasslands, mesic temperate forests, and boreal forests in the Lake States ». Journal of Sustainable Forestry 36, no 5 (17 février 2017) : 421–32. http://dx.doi.org/10.1080/10549811.2017.1296777.
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Duan, Shengwu, Hong S. He, Lauren S. Pile Knapp, Thomas W. Bonnot et Jacob S. Fraser. « Current management in national and state forests has important but limited impacts on sustaining oaks in temperate forests of the eastern U.S ». Forest Ecology and Management 546 (octobre 2023) : 121331. http://dx.doi.org/10.1016/j.foreco.2023.121331.
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Campos, Juan Antonio, Arnau Mercadé et Xavier Font. « SIVIM Deciduous Forests – Database of deciduous forests from the Iberian Peninsula ». Vegetation Classification and Survey 1 (21 décembre 2020) : 173–74. http://dx.doi.org/10.3897/vcs/2020/61776.
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“SIVIM Deciduous Forests” is a thematic database established in 2015, focused on forest vegetation from the Iberian Peninsula and southern France. It was registered in the Global Index of Vegetation Databases (GIVD ID: EU-00-023) in January 2016. All types of temperate and submediterranean non-riparian deciduous forests of the phytosociological classes Carpino-Fagetea sylvaticae, Quercetea pubescentis and Quercetea robori-petraeae (formerly combined in the class Querco-Fagetea) are represented in the database. Currently, it contains 6,642 published vegetation plots of beech, birch, ash, lime and other deciduous mixed forests, as well as forests dominated by different species of deciduous and marcescent oaks, 100% of them classified at association level. Data are stored in TURBOVEG format, and are available upon request from the international vegetation-plot databases EVA and sPlot in semi-restricted regime. The relevés have also been included in SIVIM database, and thus they are freely available online. However, in SIVIM Deciduous Forests geolocation accuracy has been improved and the taxonomy and syntaxonomy unified. Plot size is available for 73% of the relevés, of which 82% are between 100 and 400 m2. Plant taxonomy is standardized to Flora iberica. During the last four years, data of SIVIM Deciduous Forests were requested via EVA and sPlot for different projects, and have been used for several studies with various objectives, from floristic, vegetation and habitat-related topics to macroecological studies, and from local to global scales. Abbreviations: EVA = European Vegetation Archive; GIVD = Global Index of Vegetation-Plot Databases; SIVIM = Iberian and Macaronesian Vegetation Information System.
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Kvaček, Zlatko, Vasilis Teodoridis et Thomas Denk. « The Pliocene flora of Frankfurt am Main, Germany : taxonomy, palaeoenvironments and biogeographic affinities ». Palaeobiodiversity and Palaeoenvironments 100, no 3 (13 novembre 2019) : 647–703. http://dx.doi.org/10.1007/s12549-019-00391-6.
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Abstract The Pliocene flora of Frankfurt am Main described by Karl Mädler during the first half of the twentieth century is a key flora for the European Pliocene. In the present study, we revised the leaf fossil taxa described by Mädler and investigated plant material collected after Mädler’s publication. The revised and augmented floral list comprises seven new species and some new combinations of taxa described by Mädler. In total, 16 gymnosperm species in 15 genera and 73 angiosperm species (of which 15 could not be assigned to a genus) in 40 genera are recognised in the leaf record. Main characteristics of the flora are the high diversity of conifers, the diverse assemblage of exclusively deciduous Fagaceae, including six species of oaks, and the high diversity of Rosaceae. These features indicate cool temperate climatic conditions (comparable to Lugano in southern Switzerland). Angiosperm genera that are today confined to North America and/or East Asia (Eucommia, Magnolia and Sassafras) also are deciduous, whereas evergreen taxa are shrubs typical of the understorey (Buxus, Ilex, Pachysandra, Prunus lusitanica type) and Viscum. Eighteen taxa recorded in the Pliocene of Frankfurt am Main are today absent from western Eurasia and eastern North America, and 25 taxa are absent from western North America. This shows (i) a strong biogeographic link of the Pliocene flora of Frankfurt am Main with East Asia, (ii) surprisingly high levels of speciation (Pliocene endemisms) and (iii) that the European flora was more diverse in woody species shortly before the onset of major Pleistocene glaciations than today.
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Reutimann, Oliver, Felix Gugerli et Christian Rellstab. « A species-discriminatory single-nucleotide polymorphism set reveals maintenance of species integrity in hybridizing European white oaks (Quercus spp.) despite high levels of admixture ». Annals of Botany 125, no 4 (8 janvier 2020) : 663–76. http://dx.doi.org/10.1093/aob/mcaa001.
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Abstract Background and Aims Hybridization and introgression play an important role in the evolution and diversification of plants. To assess the degree of past and current hybridization, the level of genetic admixture in populations needs to be investigated. Ongoing hybridization and blurred species separation have made it challenging to assign European white oak taxa based on leaf morphology and/or genetic markers and to assess the level of admixture. Therefore, there is a need for powerful markers that differentiate between taxa. Here, we established a condensed set of single-nucleotide polymorphism (SNP) markers to reliably differentiate between the three most common oak species in temperate European forests (Quercus robur, Q. petraea, Q. pubescens) and to assess the degree of admixture in a large set of selected Swiss populations. Methods A training set of 194 presumably pure reference samples from Switzerland and Europe was used to assign 633 test individuals with two different approaches (population genetic-based/Bayesian vs. assumption-free/discriminative classifier) using 58 selected SNPs from coding regions. Admixture was calculated at the individual and population level with the Shannon diversity index based on individual assignment probabilities. Key Results Depending on the approach, 97.5–100 % of training individuals were assigned correctly, and additional analyses showed that the established SNP set could be further reduced while maintaining its discriminatory power. The two assignment approaches showed high overlap (99 %) in assigning training individuals and slightly less overlap in test individuals (84 %). Levels of admixture varied widely among populations. Mixed stands of Q. petraea and Q. pubescens revealed much higher degrees of admixture than mixed stands of the other two taxon pairs, accentuating high levels of gene flow between these two taxa in Switzerland. Conclusions Our set of SNPs warrants reliable taxon discrimination with great potential for further applications. We show that the three European white oak taxa have largely retained their species integrity in Switzerland despite high levels of admixture.