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PubMedDate not supplied

The influence of plant raw materials, containing ellagic acid and selected antibiotics on immunological response in mice.

It is demonstrated that the combined addition to a culture of aqueous extracts from tannin pharmacopoeial raw materials, containing elladic acid (Cortex Quercus, Folium Uvae ursi and Rhizoma Tormentillae) and the antibiotics: cefuroxime, cefoperazone and doxycycline influences the enhancement of survival of mouse thymocytes in cultures with supplementation of hydrocortisone. A cytotoxic test was used for the evaluation. The presented results confirmed that each of the applied aqueous extracts shows a better survival of mouse thymocytes after combined addition of an antibiotic to the culture. The extract from Cortex Quercus showed the highest activation when added to the culture with cefuroxime, whereas cefoperazone best stimulation demonstrated when combined with the extract from Rhizoma Tormentillae, and doxycycline with the extract from Folium Uvae ursi.

Animals↗
PubMed1983

Interferon research.

Two taxonomic errors appeared in the report "Oak leaf quality declines in response to defoliation by gypsy moth larvae" by J. C. Schultz and I. T. Baldwin (9 July 1982, p. 149). In the first column on page 149, Quercus rubrum should have been Quercus rubra L., and in the first column on page 150, Q. nigra should have been Q. velutina Lam.

Genetic Engineering↗
PubMedDate not supplied

Pollen calendar of the city of Salamanca (Spain). Aeropalynological analysis for 1981-1982 and 1991-1992.

We report a study on the contents of airborne pollen in the city of Salamanca (Spain) aimed at establishing a pollen calendar for the city for the yearly periods of maximum concentrations, relating these with quantifiable atmospheric variables over two two-year periods with an interval of 10 years between them: 1981-82 and 1991-92. The pollen was captured with Burkard spore-traps, based on Hirst's volumetric method. Determinations were made daily and were used to make preparations, previously stained with basic fuscin, for study under light microscopy at x 1,000 magnification. 946 preparations were analyzed, corresponding to the same number of days distributed over 150 weeks of the periods studied. The results afforded the identification of 48 different types of pollen grain: Grasses (Poaceae), Olea europea (olive), Quercus rotundifolia (Holm-oak), other Quercus spp. (Q. pyrenaica, Q. suber, Q. faginea, etc.), Cupressaceae (Cupressus sempervivens, C. arizonica, Juniperus communis etc.), Plantago (Plantago lanceolata, Plantago media, etc.), Pinaceae (Pinus communis, Abies alba, etc.), Rumex sp. (osier), Urtica dioica (nettle), Parietaria (Parietaria officinalis, P. judaica), Chenopodio-Amaranthaceae (Chenopodium sp., Amaranthus sp., Salsola kali, etc.), Artemisia vulgaris (Artemisia), other Compositae (Taraxacum officinalis, Hellianthus sp. etc.), Castanea sativa (Chestnut), Ligustrum sp. (privet), Betula sp. (birch), Alnus sp. (common alder), Fraxinus sp (ash), Populus sp. (poplar), Salix sp. (willow), Ulmus sp. (elm), Platanus sp. (plantain, plane), Carex sp. (sweet flag), Erica sp. (common heather), Leguminosae or Fabaceae:--Papillionaceae (Medicago sp.; Cercis sp., Robina sp.)--Cesalpinoideae Acacia sp. (Acacia),--Mimosoideae: Sophora japonica, Umbelliferae (Foeniculum sp., Cirsium sp., etc.), Centaurea sp., Cistus sp. (rock rose), Typha sp (bulrush), Mirtaceae (Myrtus communis), Juglans regia (Walnut), Galium verum, Filipendula sp. (spirea/drop wort), Rosaceae (Pyrus sp., Prunus sp., etc.), Tilia sp. (Linden), Morus sp. (mulberry), Taxus baccata (yew), Papaveraceae (Papaver rhoeas etc.), Labiata (Lavandula sp.), Cannabaceae (Humulus sp. etc.), Liliaceae (Lilium sp.), Echium sp. (viper's bugloss). The most abundant taxa, detected in the highest quantities (grains/m3 air), by order of counting were as follows: holm-oak, olive, grasses, Plantago and Parietaria. With the data obtained we have established a pollen calendar for Salamanca and report the period in which each type of pollen is found along the years and the periods with the highest airborne concentrations of such pollens. The diversity and the spectrum of the pollen in the city of Salamanca correspond to the typical plant communities found on the dehesas (large ranges of grasslands) of Castile, where Salamanca is located, although the wind directions and the peculiar climatic characteristics of the area govern the peaks of maximum presence of the different taxa. As examples, in the case of olive, which is cultivated at some distance from the city, its maximum presence coincides with south-westerly winds; in the case of grasses, the peaks of maximum counts coincide with a sharp rise in mean temperature, close to or higher than 20 degrees C and between five and six weeks after rainfall equal to or greater than 5 L/m2.

Air↗
PubMed2005

The holm oak leaf proteome: analytical and biological variability in the protein expression level assessed by 2-DE and protein identification tandem mass spectrometry de novo sequencing and sequence similarity searching.

As a first approach in establishing the holm oak leaf proteome, we have optimised a protocol for this plant and tissue which includes the following steps: trichloroacetic acid-acetone extraction, two-dimensional gel electrophoresis (2-DE) on pH 5 to 8 linear gradient immobilised pH gradient strips as the first dimension, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis on 13% polyacrylamide gels as the second one. Proteins were detected by Coomassie staining. Gel images were recorded and digitalized, and the protein spots quantified by using a linear regression equation of protein quantity on spot volume obtained against standard proteins. Analytical variance was calculated for one-hundred protein spots from three replicate 2-DE gels of the same protein extract. Biological variance was determined for the same protein spots from independent tissue extracts corresponding to leaves from different trees, or the same tree at different orientations or sampling times during a day. Values of 26% for the analytical variance and 58.6% for the biological variance among independent trees were obtained. These values provide a quantified and statistical basis for the evaluation of protein expression changes in comparative proteomic investigations with this species. A representative set of the major proteins, covering the isoelectric point range of 5 to 8 and the relative molecular mass(r) range of 14 to 78 kDa, were subjected to liquid chromatography-tandem mass spectrometry analysis. Due to the absence of Quercus DNA or protein sequence databases, a method based on the procedure reported by Liska and Shevchenko including de novo sequencing and BLAST similarity searching against other plant species databases was used for protein identification. Out of 43 analysed spots, 35 were positively identified. The identified proteins mainly corresponded to enzymes involved in photosynthesis and energetic metabolism, with a significant number corresponding to RubisCO.

Amino Acid Sequence↗
PubMed2004

Phaeoacremonium rubrigenum--hyphomycete associated with bark beetles found in Czechia.

Phaeoacremonium is a recently described genus (Crous et al. 1996) associated with decline diseases of woody hosts and with human infections. During a study of surface mycobiota of the oak bark beetles, the hyphomycetous microfungus Phaeoacremonium rubrigenum was isolated from larvae of Scolytus intricatus (Coleoptera: Scolytidae) and their galleries on Quercus robur and also from an adult of Leperisinus fraxini found under the bark of Fraxinus excelsior. The species determination was confirmed by rDNA (ITS1-5.8S-ITS2) comparison. P. rubrigenum was recorded for the first time in Czechia. The records on oak are considered to be the first ones in the world. A description of morphological features and figures of the fungus are given. Representative strains are maintained in the Culture Collection of Fungi (CCF), Faculty of Science, Charles University (Prague, Czechia).

Animals↗
PubMed2004

Avoidance of nonhost plants by a bark beetle, Pityogenes bidentatus, in a forest of odors.

The bark beetle, Pityogenes bidentatus (Coleoptera: Scolytidae), searches in mixed conifer and deciduous forests of northern Europe for suitable branches of its host, Scots pine ( Pinus sylvestris). We tested whether odors from several diverse nonhost trees and plants common in the habitat (e.g., mountain ash, Sorbus aucuparia; oak, Quercus robur; alder buckthorn, Frangula alnus; blueberry, Vaccinium myrtillus; raspberry, Rubus idaeus; and grass, Deschampsia flexuosa) would reduce the attraction of the bark beetle to traps releasing its aggregation pheromone components in the field. Volatiles from the leaves or bark of each of these plants significantly reduced the attraction of the beetles to their pheromone. Odors collected from these nonhosts and analyzed by GC/MS contained monoterpenes, sesquiterpenes, and "green-leaf" alcohols, several of which (e.g., 1-octene-3-ol and beta-caryophyllene) reduced the attraction to pheromone in the field and elicited electroantennographic responses. In the laboratory, reproduction by the beetle was marginal in nonhost Norway spruce, Picea abies, and was absent in the other nonhost trees. Olfactory avoidance of unsuitable nonhosts may have evolved due to advantages in avoiding mistakes during host selection.

Animals↗
PubMed2005

Establishment of two ectomycorrhizal shrub species in a semiarid site after in situ amendment with sugar beet, rock phosphate, and Aspergillus niger.

A field experiment was carried out to assess the effectiveness of the addition of sugar beet, rock phosphate, and Aspergillus niger directly into the planting hole, and the mycorrhizal inoculation of seedlings with Scleroderma verrucosum, for promotion of plant growth of Cistus albidus L. and Quercus coccifera L. and enhancement of soil physicochemical, biochemical, and biological properties, in a degraded semiarid Mediterranean area. One year after planting, the available phosphorus content in the amended soils of both species was about fourfold higher than in the nonamended soil. Amendment addition increased the aggregate stability of the rhizosphere of C. albidus (by 56% with respect to control soil) while the mycorrhizal inoculation increased only the aggregate stability of the rhizosphere of Q. coccifera (by 13% with respect to control soil). Biomass C content and enzyme activities (dehydrogenase, urease, protease-BAA, acid phosphatase, and beta-glucosidase) of the rhizosphere of C. albidus were increased by amendment addition but not by mycorrhizal inoculation. Both treatments increased enzyme activities of the rhizosphere of Q. coccifera. The mycorrhizal inoculation of the seedlings with S. verrucosum was the most effective treatment for stimulating the growth of C. albidus (by 469% with respect to control plants) and Q. coccifera (by 74% with respect to control plants). The combined treatment, involving mycorrhizal inoculation of seedlings and addition of the amendment directly into soil, had no additive effect on the growth of either shrub species.

Analysis of Variance↗
PubMed2005

Bacterial colonization of the phyllosphere of mediterranean perennial species as influenced by leaf structural and chemical features.

In this study, we assessed various leaf structural and chemical features as possible predictors of the size of the phyllosphere bacterial population in the Mediterranean environment. We examined eight perennial species, naturally occurring and coexisting in the same area, in Halkidiki (northern Greece). They are Arbutus unedo, Quercus coccifera, Pistacia lentiscus, and Myrtus communis (evergreen sclerophyllous species), Lavandula stoechas and Cistus incanus (drought semi-deciduous species), and Calamintha nepeta and Melissa officinalis (non-woody perennial species). M. communis, L. stoechas, C. nepeta, and M. officinalis produce essential oil in substantial quantities. We sampled summer leaves from these species and (1) estimated the size of the bacterial population of their phyllosphere, (2) estimated the concentration of different leaf constituents, and (3) studied leaf morphological and anatomical features and expressed them in a quantitative way. The aromatic plants are on average more highly colonized than the other species, whereas the non-woody perennials are more highly colonized than the woody species. The population size of epiphytic bacteria is positively correlated with glandular and non-glandular trichome densities, and with water and phosphorus contents; it is negatively correlated with total phenolics content and the thickness of the leaf, of the mesophyll, and of the abaxial epidermis. No correlation was found with the density of stomata, the nitrogen, and the soluble sugar contents. By regression tree analysis, we found that the leaf-microbe system can be effectively described by three leaf attributes with leaf water content being the primary explanatory attribute. Leaves with water content >73% are the most highly colonized. For leaves with water content <73%, the phosphorus content, with a critical value of 1.34 mg g(-1) d.w., is the next explanatory leaf attribute, followed by the thickness of the adaxial epidermis. Leaves higher in phosphorus (>1.34 mg g(-1) d.w.) are more colonized, and leaves with the adaxial epidermis thicker than 20.77 microm are the least colonized. Although these critical attributes and values hold true only within the Mediterranean ecosystem studied and the range of observations taken, they are important because they provide a hypothesis to be tested in other Mediterranean ecosystems and other biomes. Such comparative studies may give insight as to the general properties governing the leaf-microbe system.

Bacteria↗
PubMed2006

Host selectivity and genetic variation of Discula umbrinella isolates from two oak species: analyses of intergenic spacer region sequences of ribosomal DNA.

Discula umbrinella, a fungal endophyte of oak species, colonizes and reproduces on leaves of Quercus alba and Q. rubra in forest ecosystems. Twenty-nine isolates collected from leaves of both oak species (16 from Q. alba and 13 from Q. rubra) were assayed for oak species preference and genetic variation based on primer-specific polymerase chain reactions for the intergenic spacer region (IGS) of ribosomal DNA. DNA sequencing of the polymerase chain reaction products revealed a 10-bp insertion (237-247 bp) at the 3' end of the IGS region present in nine isolates and absent in 20 of the isolates. Phylogenetic analysis of the IGS region using the neighbor-joining method identified IGS groups (groups I-V) based on single nucleotide sequence differences. Host selectivity and geographic origin of isolates were correlated in some instances with the IGS groups. Isolates within each IGS group were further analyzed for nucleotide polymorphisms to confirm genotype identity and genotype diversity. Ten different genotypes (Va-Vj) were identified among the isolates analyzed. Genotype diversity was greatest in IGS groups I, IV, and V. Seventy percent of the genotypes (Vc, Vd, Ve, Vf, Vg,Vi, and Vj) contained isolates with single tree species preferences.

Ascomycota↗
PubMed2004

Effects of management on understory diversity in the forest ecosystems of northern Spain.

Pine plantations are an alternative to marginal agriculture in many countries, and are often presented as an option that improves biodiversity. However, these plantations can have adverse environmental effects if improperly managed. To evaluate the effect of forest management practices on biodiversity, the diversity, species richness, dominance and frequency of understory woody plant species in different forests of the Basque Country (northern Spain) were compared. Plantations of exotic conifers (Pinus radiata [D.] Don) of different ages were compared with deciduous forests of Quercus robur L. and Fagus sylvatica L. The effects of different types and intensities of management were taken into account. The differences observed were mainly conditioned by the intensity of forestry management, although the response varied according to forest type and age. In unmanaged pine plantations, the diversity and species richness of the understory increased rapidly after planting (while dominance decreased), remained stable in the intermediate age range, and reached a maximum in plantations more than 25 years of age. Management practices resulted in decreased understory diversity and species richness, as well as greater dominance. This was more pronounced in younger than in older stands. Moderate management, however, favored a greater diversity of the understory in deciduous forests. The species composition of the plantations and deciduous forests were different, the latter having a wider range of characteristic species. Knowledge of how forestry practices influence biodiversity (in terms of diversity, richness, dominance, and species composition) may allow predictions to be made about the diversity achievable with different management systems.

Ecosystem↗
PubMed2006

Plant regeneration through somatic embryogenesis from tissues of mature oak trees: true-to-type conformity of plantlets by RAPD analysis.

Somatic embryogenesis was induced in expanding leaf explants excised from epicormic shoots forced from branch segments taken at four different times of year from a mature oak (Quercus robur L.). Branch segments 2-4 cm in diameter produced most shoots when collected in March. Somatic embryos were induced on explants derived from branches of all collection dates, although collection in November seemed to afford the best results. Germination and conversion ability of embryos of embryogenic lines derived from six oak trees depended heavily on genotype, conversion rates ranging from 0 to 70%. RAPD analyses found no evidence of genetic variation either within or between the embryogenic lines established from three of these trees, or between these lines and the trees of origin, or between somatic embryo derived plantlets and the trees of origin. The embryogenic system used in this study appears to be suitable for true-to-type clonal propagation of mature oak genotypes.

Culture Media↗
PubMed2002

On-line analysis of the (13)CO(2) labeling of leaf isoprene suggests multiple subcellular origins of isoprene precursors.

Isoprene (2-methyl-1,3-butadiene) is the most abundant biogenic hydrocarbon released from vegetation, and there is continuing interest in understanding its biosynthesis from photosynthetic precursors in leaf chloroplasts. We used on-line proton-transfer-reaction mass spectrometry (PTR-MS) to observe the kinetics of (13)C-labeling of isoprene following exposure to (13)CO(2) and then the loss of (13)C after a return to normal (12)CO(2) in oak ( Quercus agrifolia Nee) and cottonwood (Populus deltoides Barr.) leaves. Assignments of labeled isoprene species were verified by gas chromatography-mass spectrometry. For the first time, it was possible to observe the half-lives of individually (13)C-labeled isoprene species during these transitions, and to trace some of the label to a C3 fragment that contained the two isoprene carbons derived from pyruvate via the deoxyxylulose-5-phosphate (DOXP) pathway. At steady state (under (13)CO(2)), approximately 80% of isoprene carbon was labeled, with fully labeled isoprene as the major species (approx. 60%). The source of the unlabeled C is suggested to be extrachloroplastic, but not from photorespiratory carbon. After a transfer to (12)CO(2), (13)C-labeling persisted in one isoprene carbon for several hours; this persistence was much more pronounced in (i) leaves inhibited by fosmidomycin, a specific inhibitor of the DOXP pathway, and (ii) in sun leaves which have higher ratios of soluble sugars to starch. From the mass 41-44 fragment data, and labeling predicted from the DOXP pathway in chloroplasts, precursors may arise from cytosolic pyruvate/phospho enolpyruvate equivalents transported into the chloroplast; this idea was supported by an indirect measure of pyruvate labeling. Other sources of cytosolic isoprene precursors (i.e. dimethylallyl diphosphate or pentose phosphate) could not be excluded. The data obtained shed light on the half-lives of photosynthetic metabolites, exchanges of carbon between cellular pools, and suggest multiple origins of isoprene precursors in leaves.

Algorithms↗
PubMed2003

A 10-kDa class-CI sHsp protects E. coli from oxidative and high-temperature stress.

We report on a new cDNA clone (Qshsp10.4-CI) of a Quercus suber L. class-CI small heat-shock protein (sHsp) obtained from cork (phellem), a highly oxidatively stressed plant tissue. The deduced gene product lacks the C-terminal extension and the consensus I region of the alpha-crystallin domain, being the most C-terminally truncated sHsp reported to date. In an attempt to prove that a protective function is possible for such a truncated sHsp, we overexpressed in Escherichia coli three recombinant sHsp-CIs, one (rQsHsp10.4-CI) showing the same truncation as Qshsp10.4-CI, a second (rN49) lacking the whole alpha-crystallin domain, and a third (rN153) consisting of a full-length sHsp-CI. The overexpression of rN153 and, remarkably, rQsHsp10.4-CI but not rN49 enhanced cell viability under high temperature and, interestingly, under oxidative stress. These results show that the C-terminal extension and the consensus I region of the alpha-crystallin domain are dispensable, but amino acids 1-41 of the alpha-crystallin domain (including the consensus II region) are essential for the protective activity of sHsp-CIs. On the other hand, two-dimensional immunodetection patterns showed accumulation of ca. 10-kDa sHsp-CI immunorelated polypeptides in cork and other oxidatively stressed tissues but not in control and heat-stressed tissues. We discuss the possible role of highly truncated sHsps in relation to oxidative stress.

Amino Acid Sequence↗
PubMed2002

Direct nocturnal water transfer from oaks to their mycorrhizal symbionts during severe soil drying.

Symbiotic mycorrhizal fungi play an important role in the absorption of soil nutrients and water by most plants. It has been suggested that hydraulically lifted water might maintain the integrity of the external mycorrhizal mycelium during drought. We tested this hypothesis in the obligately mycorrhizal species, coast live oak (Quercus agrifolia), using a microcosm system that separated the effects of hydraulic lift in roots from those in the external mycelium. Mycorrhizal oak seedlings were established in microcosms comprising three discrete compartments for (1) upper roots, (2) tap roots, and (3) external fungal mycelium. Eight months after planting, a drought treatment was initiated: irrigation to the upper root and fungal chambers was terminated and only irrigation to the taproot compartment was maintained. After 3, 12, 30, 50, 70 and 80 days of drought, tracers were injected into the taproot compartment at dusk. At dawn the following morning, mycorrhizal hyphae (EM and AM) and spores (AM) in upper root and fungal compartments were extensively labeled with the tracers. In contrast, no labeling was observed when tracers were injected into the taproot compartment during daytime. Nocturnal water translocation from plant to mycorrhizal fungi occurred in association with hydraulic lift. Saprotrophic/parasitic fungi in the microcosms were not labeled, suggesting a direct water transfer from plants to their mycorrhizal mutualists and not to other fungi in the soil. Even after prolonged drought (70-80 days), mycorrhizal hyphae persisted in soils with water potential values as low as -20 MPa. Maintaining mycorrhizal activity through direct water translocation could potentially improve the nutrient status of deep-rooted plants during periods when the fertile upper soil is dry.

Disasters↗
PubMed2004

Herbivore effects on developmental instability and fecundity of holm oaks.

Plants are able to compensate for loss of tissue due to herbivores at a variety of spatial and temporal scales, masking detrimental effects of herbivory on plant fitness at these scales. The stressing effect of herbivory could also produce instability in the development of plant modules, and measures of such instability may reflect the fitness consequences of herbivory if instability is related to components of plant fitness. We analyse the relationships between herbivory, developmental instability and production of female flowers and fruits of holm oak Quercus ilex trees by means of herbivore removal experiments. Removal of leaf herbivores reduced herbivory rates at the tree level, but had no effect on mean production of female flowers or mature fruits, whereas herbivory tended to enhance flower production and had no effect on fruit abortion at the shoot level. Differences in herbivory levels between shoots of the same branch did not affect the size and fluctuating asymmetry of intact leaves. These results indicate compensation for herbivory at the tree level and over-compensation at the shoot level in terms of allocation of resources to female flower production. Removal of insect herbivores produced an increase in the mean developmental instability of leaves at the tree level in the year following the insecticide treatment, and there was a direct relationship between herbivory rates in the current year and leaf fluctuating asymmetry the following year irrespective of herbivore removal treatment. Finally, the production of pistillate flowers and fruits by trees was inversely related to the mean fluctuating asymmetry of leaves growing the same year. Leaf fluctuating asymmetry was thus an estimator of the stressing effects of herbivory on adult trees, an effect that was delayed to the following year. As leaf fluctuating asymmetry was also related to tree fecundity, asymmetry levels provided a sensitive measure of plant performance under conditions of compensatory responses to herbivory.

Animals↗
PubMed2004

Habitat quality as a predictor of spatial variation in blue tit reproductive performance: a multi-plot analysis in a heterogeneous landscape.

Vertebrate studies have rarely investigated the influence of spatial variation in habitat richness on both short-term (breeding) and long-term (offspring recruitment) reproductive performance using simultaneously multi-patch, multi-habitat type and multi-year approaches at landscape level. Here we present results of such an approach using the influence of two oak tree (Quercus ilex, Q. humilis) species on reproductive performance in Corsican blue tits (Parus caeruleus ogliastrae) as a model system. We found that blue tits breeding in rich broad-leaved deciduous patches consistently laid eggs earlier in the season, and produced larger clutches and more fledglings of higher quality, than those breeding in poor evergreen patches. Also, parents, especially males, were in better physical condition in the broad-leaved deciduous than in the evergreen patches. Surprisingly, estimates of long-term effects of reproduction, such as recruitment rates of locally born offspring, did not differ between the two habitat types. Our results suggest that short-term breeding performance and phenotypic quality of both chicks and parents do not necessarily provide reliable information about contributions to following generations at a scale larger than that of the local study plot. Differences in reproductive performance between the two oak habitat types could not be attributed to density-dependent effects, differences in levels of nest predation, or differences in age structure of the birds. We suggest that habitats that are optimal for breeding are not necessarily optimal for survival after the breeding season.

Animals↗
PubMed2004

Perfect is best: low leaf fluctuating asymmetry reduces herbivory by leaf miners.

Fluctuating asymmetry (FA) represents small, random variation from symmetry and can be used as an indicator of plant susceptibility to herbivory. We investigated the effects of FA of two oak species, Quercus laevis and Q. geminata, and the responses of three herbivore guilds: leaf miners, gallers, and chewers. To examine differences in FA and herbivory between individuals, 40 leaves from each tree were collected, and FA indices were calculated. To examine differences in FA and herbivory within-individuals, we sampled pairs of mined and unmined leaves for asymmetry measurements. Differences in growth of leaf miners between leaf types were determined by tracing 50 mines of each species on symmetric leaves and asymmetric leaves. Asymmetric leaves contained significantly lower concentrations of tannins and higher concentrations of nitrogen than symmetric leaves for both plant species. Both frequency of asymmetric leaves on plants and levels of asymmetry positively influenced the abundance of Brachys, Stilbosis and other leaf miners, but no significant relationship between asymmetry and herbivory was observed for Acrocercops. Brachys and Stilbosis mines were smaller on asymmetric leaves, but differences in mine survivorship between symmetric and asymmetric leaves were observed only for Stilbosis mines. This study indicated that leaf miners might use leaf FA as a cue to plant quality, although differential survivorship among leaf types was not observed for all species studied. Reasons for the different results between guilds are discussed.

Animals↗
PubMed2005

Species-specific allometric scaling under self-thinning: evidence from long-term plots in forest stands.

Experimental plots covering a 120 years' observation period in unthinned, even-aged pure stands of common beech (Fagus sylvatica), Norway spruce (Picea abies), Scots pine (Pinus sylvestris), and common oak (Quercus Petraea) are used to scrutinize Reineke's (1933) empirically derived stand density rule [see text], N=tree number per unit area, [see text]=mean stem diameter), Yoda's (1963) self-thinning law based on Euclidian geometry ([see text] [see text]=mean biomass per tree), and basic assumptions of West, Brown and Enquist's (1997, 1999) fractal scaling rules ([see text] [see text] w=biomass per tree, d=stem diameter). RMA and OLS regression provides observed allometric exponents, which are tested against the exponents, expected by the considered rules. Hope for a consistent scaling law fades away, as observed exponents significantly correspond with the considered rules only in a minority of cases: (1) exponent r of [see text] varies around Reineke's constant -1.605, but is significantly different from r=-2, supposed by Euclidian or fractal scaling, (2) Exponent c of the self-thinning line [see text] roams roughly about the Euclidian scaling constant -3/2, (3) Exponent a of [see text] tends to follow fractal scaling 8/3. The unique dataset's evaluation displays that (4) scaling exponents and their oscillation are species-specific, (5) Euclidian scaling of one relation and fractal scaling of another are coupled, depending on species. Ecological implications of the results in respect to self-tolerance (common oak>Norway spruce>Scots pine>common beech) and efficiency of space occupation (common beech>Scots pine>Norway spruce>common oak) are stressed and severe consequences for assessing, regulating and scheduling stand density are discussed.

Biomass↗