共查询到20条相似文献,搜索用时 15 毫秒
1.
Climate change is one of the major issues nowadays, and Mediterranean broadleaf species have been suggested to fill possible future gaps created by climate change in Central European forests. To provide a scientific‐based foundation for such practical strategies, it is important to obtain a general idea about differences and similarities in the physiology of Central European and Mediterranean species. In the present study, we evaluated the onset of leaf senescence of a broad spectrum of oak species under the Central European climate in a common garden experiment. Degradation of the photosynthetic apparatus of evergreen (Quercus ilex, Q. suber), semi‐evergreen (Q. × turneri, Q. × hispanica) and deciduous oaks (Q. robur, Q. cerris, Q. frainetto, Q. pubescens) was monitored as chlorophyll content and analysed chlorophyll fluorescence induction transients. In the deciduous species, a significant decline in chlorophyll content was observed during autumn/winter, with Q. pubescens showing the slowest decline. Analysis of fluorescence induction transients revealed a significant decline in quantum efficiency of the primary photochemistry and reaction centre density and later, a decrease in quantum efficiency of end acceptor reduction. Alterations in fluorescence parameters were compared to the decline in chlorophyll content, which occurred much more slowly than expected from the fluorescence data. The evergreen species showed no decline in chlorophyll content, nor different chlorophyll a fluorescence induction behaviour despite temperature falling below 0 °C. The hybrids showed intermediate behaviour between their parental evergreen and deciduous taxa. 相似文献
2.
Oaks (Quercus spp.) represent the most important broadleaf genus with respect to forest-shaping tree species in the Mediterranean. Considering future climate scenarios (increased drought conditions), the identification of drought tolerant oak species is of great importance for future forest management in this region. The objective of the study was the comparison of physiological status of three economically and ecologically valuable oak species (Quercus ilex, Quercus frainetto and Quercus pubescens) co-existing in natural coppice stands in NE Greece, in response to seasonal drought stress. Measurements were conducted between June and September 2016, every 15–20 days until leaf falling. The parameters studied were predawn leaf water potential and fast chlorophyll fluorescence induction curves (OJIP test), chlorophyll content, and relative water content. Meteorological data from the area were also collected. Photosynthetic parameters such as performance indices (PIabs and PItot) reacted to summer drought conditions, with Q. frainetto showing the lowest values. The discrepancy between species increased with duration of drought period. Q. frainetto revealed the lowest predawn water potential values. The results indicate that Q. frainetto is less suitable for future forestry applications in the studied climate/elevation zone than Q. pubescens and Q. ilex. 相似文献
3.
Abstract. Germination of Quercus ilex L. in coppice stands of this species in the western Mediterranean Basin was examined and a germination inhibitory process is proposed to explain some germination traits. Germination rate and seedling biomass of Q. ilex were greatly modified by watering acorns with various concentrations of aqueous soil extracts from a Q. ilex coppice stand but also when the acorns were sown in soil from Q. ilex coppice stands. In the aqueous extract experiment, Q. ilex germination and seedling weight both decreased as the aqueous extract concentration increased. In the soil type experiment, Q. ilex soil decreased the Q. ilex germination rate. Comparative studies with Q. pubescens germination (this species, replaced by Q. ilex around 5 000 B.P., is assumed to form the climax vegetation of the region) revealed that Q. pubescens was less sensitive to the aqueous extracts and soils of Q. ilex coppice stands. Inhibition of Q. ilex seed germination could be a major reason for the poor seed regeneration and suggested a possible comeback of Q. pubescens. 相似文献
4.
Attachment may be a basis for specialization in oak aphids 总被引:4,自引:0,他引:4
C. E. J. KENNEDY 《Ecological Entomology》1986,11(3):291-300
ABSTRACT.
- 1 The potential role of tarsal attachment in host selection was studied in the specialist aphids Tuberculoides annulatus Hartig and Myzocallis schreiberi Hille Ris Lambers and Stroyan.
- 2 M.schreiberi could walk freely on its host, Quercus ilex and on Q.robur, whereas T.annulatus could walk freely on its host, Q.robur but had difficulty on Q. ilex.
- 3 Attachment to the rough-textured leaves of Q.robur was achieved by means of the pretarsal claws, and to the smooth upper surface of individual trichomes on the lower surface of Q.ilex using flexible pretarsal empodia.
- 4 Both behavioural and allometric differences can account for the inability of T.annulatus to grip onto Q.ilex.
- 5 The role of attachment by phytophagous insects in host plant resistance and selection is discussed.
5.
We investigated the responses of two co‐existing Mediterranean trees with different regeneration strategies (Phillyrea latifolia seedlings and Quercus ilex sprouts) to experimental drought below the forest canopy. We considered different recruitment stages and used leaf isotopic discrimination to estimate water use efficiency (WUE) and nitrogen availability and use. Drought decreased the emergence and survival of seedlings and sprouts. Survival and growth of older saplings were not influenced by drought. Seedling emergence of P. latifolia was higher than Q. ilex sprout production, but Q. ilex sprouts had higher survival and growth rates. These differences disappeared in the sapling stage. Carbon isotopic discrimination suggested that Q. ilex sprouts had higher WUE than P. latifolia seedlings. Drought increased WUE of recruits, particularly in Q. ilex. Water use regulation increased with ageing, particularly in P. latifolia. Q. ilex had higher δ15N values than P. latifolia; these were also higher under drier soil conditions. Current year seedlings had higher δ15N than saplings, particularly in P. latifolia, suggesting they exploit superficial soil layers. These results suggest that sprouts obtain benefit from resources stored in parent plants. At earlier stages, they perform better than seedlings. This response is not coupled to adult vulnerability to drought for these species, revealing the difficulty of predicting species dynamics during climate change. 相似文献
6.
Allozyme variation at 14 loci was studied electrophoretically in 19 population samples of Quercus cerris, Q. pubescens, Q. petraea, and Q. robur. Genetic variation, measured as mean heterozygosity, was found to be high within populations but low among populations. A significant deficit of heterozygotes was observed in most of the populations of Q. pubescens, Q. petraea, and Q. robur. At the species level, Q. cerris (sect. Cerris) appears to be clearly separated from the rest (sect. Quercus). Q. pubescens, Q. petraea, and Q. robur form a cluster of closely-related species. The degree of genetic differentiation among these species is low, i.e. in the range normally found among con-specific populations. Nevertheless, allozyme data allow the elaboration of a dendrogram which is in reasonable accordance with the taxonomic classification, but also supports the importance of hybridization and introgression. This is also underlined by the fact that the allelic differentiation at the Got-2 locus corresponds with the phenotypic classification (petraea-like, hybrids, and robur-like) in samples from mixed populations. 相似文献
7.
Bastien Gérard Badr Alaoui-Sossé Pierre-Marie Badot 《Trees - Structure and Function》2009,23(2):373-380
Pedunculate (Quercus robur L.) and sessile (Q. petraea [Matt.] Liebl.) oaks are the most common oak species in Western Europe. They are known to display different ecological requirements,
particularly relative to root hypoxia induced by flooding: In a glasshouse study of seedlings, we quantified the effects of
flooding on starch mobilization from cotyledons and starch partitioning. Growth and distribution of lateral roots were also
measured. The above-ground growth of Q. robur was less affected by flooding than that of Q. petraea which failed to develop a second flush. Root growth was also severely inhibited, particularly in Q. petraea. In Q. robur, lateral root initiation as well as elongation was restricted to the soil surface layer. Flooding markedly reduced total
growth and concentrations of in all components except stems. Starch mobilization from cotyledons was delayed by flooding,
especially in Q. robur seedlings. Under flooding, the decrease of cotyledons dry mass and starch content in Q. robur was lower than in Q. petraea, whereas Q. robur displayed larger growth than Q. petraea. The features of carbohydrate management may be crucial in the observed differences in flooding tolerance of these species. 相似文献
8.
Molecular-cytogenetic studies of ribosomal genes and heterochromatin reveal conserved genome organization among 11 Quercus species 总被引:1,自引:0,他引:1
V. Zoldos D. Papes M. Cerbah O. Panaud V. Besendorfer S. Siljak-Yakovlev 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,99(6):969-977
Genomes of 11 Quercus species were characterized using cytogenetic (Giemsa C-banding, fluorochrome banding), molecular-cytogenetic (fluorescence in situ hybridization, FISH, to ribosomal genes) and molecular (dot-blot for ribosomal gene-copy number assessment) techniques. Ribosomal
genes are the first DNA sequences to be physically mapped in oaks, and the copy number of the 18S-5.8S-26 S rRNA genes is
estimated for the first time. Oak karyotypes were analysed on the basis of DAPI banding and FISH patterns; five marker chromosomes
were found. In addition, chromosomal organization of ribosomal genes with respect to AT- and GC-differentiated heterochromatin
was studied. Fluorochrome staining produced very similar CMA/DAPI banding patterns, and the position and number of ribosomal
loci were identical for all the species studied. The 18S-5.8S-26 S rRNA genes in oak complements were represented by a major
locus at the subterminal secondary constriction (SC) of the only subtelocentric chromosome pair and a minor locus at paracentromeric
SC of one metacentric pair. The only 5 S rDNA locus was revealed at the paracentromeric region of the second largest metacentric
pair. A striking karyotypic similarity, shown by both fluorochrome banding and FISH patterns, implies close genome relationships
among oak species no matter their geographic origin (European or American) or their ecophysiology (deciduous or evergreens).
Dot-blot analysis gave preliminary evidence for different copy numbers of 18S-5.8S-26 S rRNA genes in diploid genomes of Q. cerris, Q. ilex, Q. petraea, Q. pubescens and Q. robur (2700, 1300, 2200, 4000 and 2200 copies, respectively) that was correlated with the size polymorphism of the major locus.
Received: 26 February 1999 / Accepted: 16 March 1999 相似文献
9.
The possible role in drought resistance played by sclerophyllywas studied in the Mediterranean oaks Quercus ilex, Q. suberand Q. pubescens. Studies were conducted on leaves at 30, 50and 80% of their final surface area, as well as on mature leavesof the current year's growth in June and September and on 1-year-oldleaves. Leaves of different ages of the three species showed quite differentdegrees of sclerophylly (DS). Q. ilex leaves reached the definitiveDS of 1.75 g dm2 during leaf expansion; Q. pubescensleaves hardened at the end of their expansion, with a finalDS of 0.93 g dm2; Q. suber showed the lowest DS of 0.76g dm2. Leaf conductance to water vapour (g1) of 1-year-old leaves ofQ. ilex, measured in the field, showed a duration of the g1peak values about twice that of the other two species. The minimumleaf relative water content (RWC), however, was near the samein the three species, indicating that water loss was recoveredpartly by Q. ilex leaves. This was apparently due to the higherbulk modulus of elasticity ( 相似文献
10.
Abstract In this study, leaf morphology was assessed in a mixed oak stand (western France) using two geometric morphometric (landmark and outline) datasets and one dataset of 19 leaf measures. Adult oaks (817 oaks), comprising four white oak species (Quercus petraea, Q. robur, Q. pubescens and Q. pyrenaica), were sampled for DNA extraction and genetic analysis (nuclear microsatellites). Leaf morphology was assessed on 336 oaks, comprising pure species and hybrids as determined by genetic assignment. This comparative study of oak leaf morphology, based on the use of two free size geometric morphometric methods and a set of leaf measurements, combined with the genetic assignment of individuals to pure species or hybrids, provided information about the differences among species and the intermediate leaf morphology of their hybrids. 相似文献
11.
Five-year-old trees of deciduous Quercus robur L., evergreen Q. ilex L., and their semideciduous hybrid, Q. × turneri Willd. (var. pseudoturneri), growing in pots, were subjected to drought stress by withholding water for 18–22 days, until leaf water potentials decreased below ?2 MPa. Gas-exchange rates, oxygen evolution, and modulated chlorophyll (Chl) fluorescence measurements revealed that by strong stomata closure and declining photosynthetic capacity down to approximately 50%, all three taxa responded with strongly reduced photosynthesis rates. In Q. robur, photochemical quenching of the drought-stressed plants was much lower than in nonstressed controls. Dissection of the occurring events in the photosynthetic electron transport chain by fast Chl fluorescence induction analysis with the JIP-test were discussed. 相似文献
12.
Leaf development of Quercus robur (deciduous), Q. ilex (evergreen) and of their hybrid Q. × turneri was assessed under Central European climate conditions. In all three taxa, development of maximum photosynthetic capacity
was slow, although whole chain electron transport, grana development, the xanthophyll cycle and the biochemical capacity for
photosynthesis were already completely present at day 7 after budbreak (DAB 7). In the course of the following 30 days, shifts
in the levels of metabolites of the photosynthetic dark reactions were observed, indicating a change from ribulose bisphosphate
(RubP) regeneration limitation towards RubP consumption limitation of photosynthesis. At the same time, electron transport
rates had strongly increased and the capacity of the light reactions did not seem to limit photosynthesis. Sucrose levels
in the leaves increased strongly, indicating sink limitation of photosynthesis, which might be responsible for the observed
slow development of maximum photosynthetic capacity in all three taxa. 相似文献
13.
Corcuera Leyre Camarero Jesús Julio Gil-Pelegrín Eustaquio 《Trees - Structure and Function》2004,18(1):83-92
We assessed the response of Quercus ilex subsp. ballota to the severe summer drought recorded in 1994 in NE Spain through the study of changes in radial growth and wood anatomy. We selected a coppice stand in the Iberian Peninsula, which is characterized by a Mediterranean climate under continental influence. We measured internode length, tree-ring width, mean and maximum vessel diameter, and vessel density for 1981–1997. The annual predicted hydraulic conductance (Kh) was calculated following Hagen-Poisseuille's law. We compared the tree-ring width, vessel diameter and Kh of Q. ilex subsp. ballota and co-existing ring-porous oaks (Q. faginea, Q. pyrenaica) for a dry summer (1994) and a wet summer (1997). To evaluate the drought-resistance of xylem for Q. ilex subsp. ballota (dominant under continental conditions) and Q. ilex subsp. ilex (dominant in mild areas) we determined vulnerability curves. Dimensionless indices of internode length, tree-ring width, and vessel density were compared with climatic data (monthly total precipitation and mean temperature) using correlation analyses. Internode length, tree-ring width, Kh, and mean and maximum vessel diameter declined in 1994. According to vulnerability curves, Q. ilex subsp. ballota showed a greater drought resistance than Q. ilex subsp. ilex. During the year of growth, we found a positive influence of January and June–August precipitation on the internode length, tree-ring width, and vessel density. The response of Q. ilex subsp. ballota radial-growth to summer drought was comparable to that of Q. faginea latewood. Overall, growth and wood anatomy of Q. ilex subsp. ballota showed a plastic response to drought. 相似文献
14.
Photosynthetic induction responses of two rainforest tree species in relation to light environment 总被引:4,自引:0,他引:4
Photosynthetic induction of in situ saplings of two Costa Rican rainforest tree species wre compared in relation to their light environment, using infrared gas analysis and hemispherical photography. The species studied were Dipteryx panamensis, a climax species found in bright microsites, and Cecropia obtusifolia, a pioneer species. In the morning, when leaves were most responsive, induction time necessary to reach 90% of the lightsaturated rate of photosynthesis was on average 16 min for Dipteryx and 10 min for Cecropia. However, induction times for both species increased in the afternoon resulting in shorter daily average induction times for Dipteryx than for Cecropia. Dipteryx also maintained higher levels of induction for a longer period under low light conditions than did Cecropia. The two species differed in the way they adjusted to light availability. Dipteryx saplings growing in shady sites had faster rates of induction than saplings growing in bright sites, with no difference in light-saturated photosynthetic rate. In contrast, Cecropia saplings growing in bright sites had higher light-saturated photosynthetic rates than saplings growing in shady sites, with no difference in rates of induction. Dipteryx appears to exploit temporal variation in light availability by refining the quickness of the induction response to the light environment, while Cecropia adjusts its scale of exploitation by realizing a higher lightsaturated photosynthetic rate in sites of higher light. 相似文献
15.
Increasing carbon discrimination rates and depth of water uptake favor the growth of Mediterranean evergreen trees in the ecotone with temperate deciduous forests
下载免费PDF全文
![点击此处可从《Global Change Biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tree populations at the low‐altitudinal or ‐latitudinal limits of species' distributional ranges are predicted to retreat toward higher altitudes and latitudes to track the ongoing changes in climate. Studies have focused on the climatic sensitivity of the retreating species, whereas little is known about the potential replacements. Competition between tree species in forest ecotones will likely be strongly influenced by the ecophysiological responses to heat and drought. We used tree‐ring widths and δ13C and δ18O chronologies to compare the growth rates and long‐term ecophysiological responses to climate in the temperate‐Mediterranean ecotone formed by the deciduous Fagus sylvatica and the evergreen Quercus ilex at the low altitudinal and southern latitudinal limit of F. sylvatica (NE Iberian Peninsula). F. sylvatica growth rates were similar to those of other southern populations and were surprisingly not higher than those of Q. ilex, which were an order of magnitude higher than those in nearby drier sites. Higher Q. ilex growth rates were associated with high temperatures, which have increased carbon discrimination rates in the last 25 years. In contrast, stomatal regulation in F. sylvatica was proportional to the increase in atmospheric CO2. Tree‐ring δ18O for both species were mostly correlated with δ18O in the source water. In contrast to many previous studies, relative humidity was not negatively correlated with tree‐ring δ18O but had a positive effect on Q. ilex tree‐ring δ18O. Furthermore, tree‐ring δ18O decreased in Q. ilex over time. The sensitivity of Q. ilex to climate likely reflects the uptake of deep water that allowed it to benefit from the effect of CO2 fertilization, in contrast to the water‐limited F. sylvatica. Consequently, Q. ilex is a strong competitor at sites currently dominated by F. sylvatica and could be favored by increasingly warmer conditions. 相似文献
16.
A strong selection for acorn characteristics is expected to have evolved in the mutualistic relationship between the European jay (Garrulus glandarius) and the oak (Quercus spp.). Bossema's pioneer work suggested that jays do not select acorns randomly, but rather they preferentially select some size and species. Preference for some seeds over others may have implications on plant community dynamics by conferring advantages (or disadvantages) on the selected (avoided) seed characteristics. In this paper we test to what extent jays select acorns by species and/or by size and the relation between these two traits in Mediterranean oak species. The experiments consist of a set of field tests in which acorns from four different coexisting Mediterranean oak species (Quercus ilex, Quercus faginea, Quercus suber, and Quercus coccifera) were placed in artificial feeders accessible to wild jays. The acorns were previously measured to control individual acorn characteristics. Using video-recording techniques, we followed jay activity and the fate of each acorn (sequence of acorn selection and method of transport). Q. ilex acorns were preferred over other acorns, and Q. coccifera acorns were avoided when other acorns were available. Preference for Q. faginea and Q. suber acorns was intermediate, that is, they were preferred over Q. coccifera acorns but not over Q. ilex acorns. Large acorns were also preferred although acorn species selection was stronger than size selection. Jays selected species and size both by visual means and by using acorn area as an indicator of size. Acorns wider than 17–19 mm were carried in the bill because of throat limitation. Our results confirm Bossema's study on temperate oaks and extend it to Mediterranean oak species, revealing implications on mixed oak forest dynamics. 相似文献
17.
Patterns of contemporary hybridization inferred from paternity analysis in a four-oak-species forest
Background
Few studies address the issue of hybridization in a more than two-species context. The species-rich Quercus complex is one of the systems which can offer such an opportunity. To investigate the contemporary pattern of hybridization we sampled and genotyped 320 offspring from a natural mixed forest comprising four species of the European white oak complex: Quercus robur, Q. petraea, Q. pubescens, and Q. frainetto. 相似文献18.
Quercus ilex L. (holm oak) coppices, widespread around the Mediterranean basin, are probably the result of 5 000 years of prolonged human disturbance of the original Quercus pubescens Willd. (downy oak) forests. Since disturbance has almost ceased in recent years, a question arises as to the development of these coppices: will the Q. pubescens forests return, or will Q. ilex remain the dominant species? To investigate the phenomenon, we analyzed the first stages, i.e. germination of the two species in holm oak coppices. Our experiments show that both species germinated better in coppices than in clearings or clear-cuts. Moreover, Q. pubescens appears to be slightly favored above Q. ilex and it is suggested auto-allelopathy is involved, at least partially inhibiting the germination of Q. ilex. 相似文献
19.
Lorenzo Cotrozzi Damiano Remorini Elisa Pellegrini Marco Landi Rossano Massai Cristina Nali Lucia Guidi Giacomo Lorenzini 《Physiologia plantarum》2016,157(1):69-84
Despite the huge biodiversity characterizing the Mediterranean environment, environmental constraints, such as high sunlight and high temperatures alongside with dry periods, make plant survival hard. In addition, high irradiance leads to increasing ozone (O3) concentrations in ambient air. In this era of global warming, it is necessary to understand the mechanisms that allow native species to tolerate these environmental constraints and how such mechanisms interact. Three Mediterranean oak species (Quercus ilex, Quercus pubescens and Quercus cerris) with different features (drought tolerant, evergreen or deciduous species) were selected to assess their biometrical, physiological and biochemical responses under drought and/or O3 stress (80–100 nl l?1 of O3 for 5 h day?1 for 77 consecutive days). Leaf visible injury appeared only under drought stress (alone or combined with O3) in all three species. Drought × O3 induced strong reductions in leaf dry weight in Q. pubescens and Q. cerris (?70 and ?75%, respectively). Alterations in physiological (i.e. decrease in maximum carboxylation rate) and biochemical parameters (i.e. increase in proline content and build‐up of malondialdehyde by‐products) occurred in all the three species, although drought represented the major determinant. Quercus ilex and Q. pubescens, which co‐occur in dry environments, were more tolerant to drought and drought × O3. Quercus ilex was the species in which oxidative stress occurred only when drought was applied with O3. High plasticity at a biochemical level (i.e. proline content) and evergreen habitus are likely on the basis of the higher tolerance of Q. ilex. 相似文献
20.
The sclerophyllous forests of Quercus ilex (holm oak) possess a unique position in earth’s biosphere, existing only in countries of the Mediterranean basin. However, very little information exists about mushrooms associated with holm oak in east Mediterranean, including Greece, where Q. ilex appears mostly in relict forests and fragmented stands. A pertinent long-term investigation was undertaken in selected Q. ilex dominated habitats of Crete, Andros, Naxos and Ikaria islands (Aegean Archipelago) as well as in mountains of Attica. Specimens of xylotrophic basidiomycetes were collected and identified. As a result, 74 species were recorded; among them Hemimycena cephalotricha, Hyphoderma cremeoalbum, Hyphodontia radula, Irpex litschaueri, Mycena algeriensis, Phanerochaete martelliana, Phloeomana alba and Phlebia unica constitute new records for the Greek mycobiota, while 68 species are reported for the first time on Q. ilex in Greece. Moreover, the presence of Fomitiporia mediterranea on this host was evidenced through ITS sequencing, and comments are made about its relationship to F. punctata and F. pseudopunctata. The importance of findings is discussed in conjunction with their environmental value; five species could be assigned in the “Species of Special Interest” categories, and other five polypores are proposed as suitable indicators for Q. ilex habitat assessment and conservation. 相似文献