Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Quercus”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources
PubMed1990

Comparative studies of delignification caused by ganoderma species.

Isolates of six species of Ganoderma in the G. lucidum complex were evaluated for their ability to decay wood of Quercus hypoleucoides A. Camus and Abies concolor (Gord. and Glend.) Lindl. ex. Hildebr. by using in vitro agar block decay tests. Morphological, ultrastructural, and chemical studies of decayed wood were used to determine the extent of delignification or simultaneous decay caused by each species of Ganoderma. All species decayed both white fir and oak wood; however, less percent weight loss (%WL) occurred in white fir than oak. In white fir, isolates of two undescribed Ganoderma species (RLG16161, RLG16162, JEA615, and JEA625) caused significantly higher%WL (21 to 26%) than that in G. colossum, G. oregonense, G. meredithiae, and G. zonatum (10 to 16%). Only Ganoderma sp. isolates JEA615 and JEA625 caused delignification, with JEA615 causing a lignin-to-glucose gram loss ratio of 1.6:1. Morphological and ultrastructural studies confirmed delignification by this fungus and showed that some delignification had occurred by all of the species, although areas of delignification were limited to small regions adjacent to simultaneously decayed cells. In oak, G. colossum caused significantly less%WL (22 to 35%) than the other species (38 to 52%). All of the species, except G. meredithiae, caused delignification with lignin-to-glucose gram loss ratios ranging from 1.4 to 4.9:1. Extensive delignification by isolates of G. colossum and G. oregonense was observed; moderate delignification was caused by the other species. Ganoderma meredithiae caused a simultaneous decay, with only small localized regions of cells delignified, while delignification by G. zonatum was irregular, with specific zones within the cell wall delignified. The thermophilic and chlamydosporic G. colossum has the capacity to cause extensive delignification and appears ideally suited for use in lignin degradation studies and biotechnological applications of lignin-degrading fungi.

Journal Article↗
PubMed1993

Microbial decomposition of elm and oak leaves in a karst aquifer.

Dry Chinquapin oak (Quercus macrocarpa) and American elm (Ulmus americana) leaves were placed in four microcosms fed by groundwater springs to monitor changes in dry mass, ash-free dry mass, and microbial activity over a 35-day period. Oxygen microelectrodes were used to measure microbial activity and to estimate millimeter-scale heterogeneity in that activity. Oak leaves lost mass more slowly than elm leaves. Generally, there was a decrease in total dry weight over the first 14 days, after which total dry weight began to increase. However, there were consistent decreases in ash-free dry mass over the entire incubation period, suggesting that the material remaining after initial leaf decomposition trapped inorganic particles. Microbial activity was higher on elm leaves than on oak leaves, with peak activity occurring at 6 and 27 days, respectively. The level of oxygen saturation on the bottom surface of an elm leaf ranged between 0 and 75% within a 30-mm area. This spatial heterogeneity in O(2) saturation disappeared when the water velocity increased from 0 to 6 cm s. Our results suggest that as leaves enter the groundwater, they decompose and provide substrate for microorganisms. The rate of decomposition depends on leaf type, small-scale variations in microbial activity, water velocity, and the length of submersion time. During the initial stages of decomposition, anoxic microzones are formed that could potentially be important to the biogeochemistry of the otherwise oxic aquifer.

Journal Article↗
PubMed1995

Effects of Incubation Time and Temperature on In Vitro Selective Delignification of Silver Leaf Oak by Ganoderma colossum.

The effects of incubation time and temperature on the ability of isolates of the chlamydosporic and thermophilic fungus Ganoderma colossum (Fr.) C. F. Baker to cause selective delignification of Quercus hypoleucoides A. Camus were evaluated by standard in vitro agar block tests. Chemical and scanning electron microscopy studies of decayed wood were used to determine the extent of selective delignification or simultaneous decay caused by each fungal isolate. At 35 deg C, the percent weight loss increased from 6.1% after 4 weeks to a maximum of 32.5 to 33.0% after 16 and 20 weeks of incubation. The average percent Klason lignin-chlorite holocellulose ratios (PKL/CHC) decreased from 0.35 in the control wood block to 0.22 in wood blocks incubated for 12 weeks; this indicated selective delignification. The average PKL/CHC increased for the 16- and 20-week incubation periods, indicating greater removal of polysaccharides during longer incubation periods. In temperature studies, the percent weight loss after 12 weeks was 26 to 27% between 30 and 40 deg C and less than 16% for the 25 and 45 deg C treatments. The average PKL/CHC ranged from 0.18 to 0.16 between 35 and 40 deg C, whereas they were 0.23 and 0.31 for the 25 and 45 deg C treatments, respectively. Scanning electron microscopy confirmed an optimum temperature range near 35 to 40 deg C and incubation times of 8 to 12 weeks for selective delignification. Under these conditions, ray parenchyma, fiber tracheids, and vessels were devoid of middle lamella; pit regions of cells were visible with significantly enlarged apertures; and individual cells were separated and clearly delimited. Extensive delignification of wood occurred throughout the wood blocks evaluated. Incubation times longer than 12 weeks resulted in greater degradation of wood cell walls and thus in greater removal of the polysaccharide component of the wood. For incubation times of 4 weeks or a temperature of 25 deg C, limited to no degradation of cells was observed. At 45 deg C, walls of fiber tracheids were eroded and ray parenchymal cells were extensively degraded, indicating that simultaneous degradation of cell walls occurred. Thus, the incubation temperature influenced the type of decay by G. colossum observed on oak wood blocks: extensive selective delignification at 35 to 40 deg C after more than 8 weeks of incubation or simultaneous decay at 45 deg C with 14% weight loss after 12 weeks of incubation. Isolates of G. colossum may prove useful in studies on mechanisms of delignification and biotechnological applications (e.g., biopulping) of lignin-degrading fungi.

Journal Article↗
PubMed1995

Quantification of fungal hyphae in leaves of deciduous trees by automated image analysis.

An optical method to quantify the fungal hyphae within decomposing leaves of deciduous trees was developed. The plant matrix was partially destroyed under hydrolytic conditions, and fungal hyphae and cellulose residues within the leaves were stained with Calcofluor M2R. Cellulose residues were subsequently depolymerized by cellulase, and fungal hyphae were separated from the remaining plant matrix with a pressurized air-water mixture. An image analysis program to quantify the fungal hyphae was written. The program included the recognition of fungal hyphae, the elimination of stomata from the images, and the measuring of lengths of fungal hyphae. The optical method was verified by a chemical method relying on glucosamine as an indicator of fungal biomass. The fungal biomass in leaves of Fagus silvatica and Quercus petraea at early states of decomposition was 0.2 to 0.4% of the leaf weight. The biomass reached a maximum within 2 to 4 weeks (optical method, 0.5 to 0.7%; chemical method, 1 to 1.4% of the initial leaf weight) and decreased thereafter.

Journal Article↗
PubMed2000

Biochemical and molecular characterization of a laccase from Marasmius quercophilus.

The basidiomycete Marasmius quercophilus is commonly found during autumn on the decaying litter of the evergreen oak (Quercus ilex L.), a plant characteristic of Mediterranean forest. This white-rot fungus colonizes the leaf surface with rhizomorphs, causing a total bleaching of the leaf. In synthetic liquid media, this white-rot fungus has strong laccase activity. From a three-step chromatographic procedure, we purified a major isoform to homogeneity. The gene encodes a monomeric glycoprotein of approximately 63 kDa, with a 3.6 isoelectric point, that contains 12% carbohydrate. Spectroscopic analysis of the purified enzyme (UV/visible and electron paramagnetic resonance, atomic absorption) confirmed that it belongs to the "blue copper oxidase" family. With syringaldazine as the substrate, the enzyme's pH optimum was 4.5, the optimal temperature was 75 degrees C, and the K(m) was 7.1 microM. The structural gene, lac1, was cloned and sequenced. This gene encodes a 517-amino-acid protein 99% identical to a laccase produced by PM1, an unidentified basidiomycete previously isolated from wastewater from a paper factory in Spain. This similarity may be explained by the ecological distribution of the evergreen oak in Mediterranean forest.

Agaricales↗
PubMed2005

Phytophthora ramorum: integrative research and management of an emerging pathogen in California and Oregon forests.

Phytophthora ramorum, causal agent of sudden oak death, is an emerging plant pathogen first observed in North America associated with mortality of tanoak (Lithocarpus densiflorus) and coast live oak (Quercus agrifolia) in coastal forests of California during the mid-1990s. The pathogen is now known to occur in North America and Europe and have a host range of over 40 plant genera. Sudden oak death has become an example of unintended linkages between the horticultural industry and potential impacts on forest ecosystems. This paper examines the biology and ecology of P. ramorum in California and Oregon forests as well discussing research on the pathogen in a broader management context.

California↗
PubMed2001

[Frequency of the common cold in healthy subjects during exposure to a lectin-rich and a lectin-poor mistletoe preparation in a randomized, double-blind, placebo-controlled study].

BACKGROUND/OBJECTIVE: Mistletoe preparations have immunomodulatory properties in vitro and in vivo. We wanted to investigate whether or not these properties have an effect on the frequency of the common cold in healthy subjects. PROBANDS AND METHODS: During a randomized, placebo-controlled, double-blind study 16 volunteers received the mistletoe lectin(ML)-poor preparation Iscador Pini(R) (IP), 16 the ML-rich preparation Iscador Quercus spezial(R) (IQ), and 16 placebo (physiological saline solution) twice a week subcutaneously for 12 weeks. Weekly during weeks 1-12 and finally at week 26, a careful history of common cold symptoms was taken. Because the frequency of the common cold was not the main outcome criterion in this study, the number of cases needed to treat was not adjusted to this criterion. RESULTS: The mean frequency of the common cold during the 12 weeks of injection was 1.5 in the placebo, 1.4 in the IP and 1.1 in the IQ group. During this period in 2.3 (placebo), 1.9 (IP) and 1.4 (IQ) weeks symptoms of common cold were present. The difference in favor to IQ lasted until the end of the observation period in week 26. It was, however, not significant. Leukocyte and granulocyte count as well as C-reactive protein were not different between the groups. CONCLUSIONS: The study showed a trend (p = 0.4, exact Kruskal- Wallis test) to reduced frequency and duration of the common cold in subjects who were exposed to IQ.

Adult↗
PubMed1995

Active-oxygen scavenging activity of plant extracts.

To find antioxidative compounds present in plants, 65 types of plant extract were tested using the neotetrazolium method for evidence of superoxide anion-scavenging effects and 7 plant extracts were selected for further investigation. The activity of active-oxygen scavengers such as superoxide anion radicals, hydroxyl radicals, singlet oxygens and lipid peroxides in the 7 plant extracts (Aeseclus hippocastanum L., Hamamelis virginiana L. Polygonum cuspidatum Sieb., Quercus robur L., Rosemarinous officinalis L., Salvia officinalis L. and Sanguisorba officinalis L.) was examined in detail by both ESR spin-trapping and malondialdehyde generation. Furthermore, the active-oxygen scavenging activity of these plant extracts was evaluated using a murine dermal fibroblast culture system. Both Aeseclus hippocastanum L. and Hamamelis virginia L. were found to have strong active-oxygen scavenging activity of and protective activity against cell damage induced by active oxygen. Both Aeseclus hippocastanum L. and Hamamelis virginiana L. are proposed as potent plant extracts with potential application as anti-aging or anti-wrinkle material for the skin.

Animals↗
PubMed1995

Inhibitory effects of Egyptian folk medicines on human immunodeficiency virus (HIV) reverse transcriptase.

Extracts of 41 medicinal plants used in Egyptian folk medicine were screened for their inhibitory effects on human immunodeficiency virus-1 reverse transcriptase. The extracts of fruits of Phyllanthus emblica, Quercus pedunculata, Rumex cyprius, Terminalia bellerica, Terminalia chebula and Terminalia horrida showed significant inhibitory activity with IC50 < or = 50 micrograms/ml. Through a bioassay guided-fractionation of the methanol extract of the fruit of P. emblica, putranjivain A (1) was isolated as a potent inhibitory substance with IC50 = 3.9 microM, together with 1,6-di-O-galloyl-beta-D-glucose (2), 1-O-galloyl-beta-D-glucose (3), kaempferol-3-O-beta-D-glucoside (4), quercetin-3-O-beta-D-glucoside (5) and digallic acid (6). The inhibitory mode of action by 1, 2 and 6 was non-competitive with respect to the substrate but competitive with respect to a template-primer. Furthermore, the stereochemistry of 1 was established in this paper by nuclear magnetic resonance spectroscopy.

Carbohydrate Conformation↗
PubMed1998

[Anti-dermaptophyte activity of phenolic compounds in "mokusaku-eki"].

"Mokusaku-eki," a kind of pyroligneous acid, is a dark brown color solution obtained from the charcoal burner of such Quercus spp. woods as a by-product. This is used as a folk medicine in water eczema. The n-hexane fraction of this solution contained several phenolic compounds such as 4-ethyl-2-methoxyphenol (3) and 2,6-dimethoxyphenol (4), which could not be found in the fresh woods. Among these compounds, 3 has the highest anti-dermaptophyte activity against Trichophyton mentagrophytes at minimum inhibitory concentration (MIC) 150 micrograms/ml.

Alkaloids↗
PubMed2003

Transmitted and reflected scattering matrices from an English oak leaf.

The complete Mueller matrix for an English oak (Quercus robur) leaf for a fixed azimuth angle (90 degrees) was determined immediately after plucking and a day following exposure to normal room temperature and pressures. The Mueller matrices were determined for transmitted light at observation angles ranging from 0 degrees to 24 degrees and for reflected backscattering angles from 153 degrees to 170 degrees. All the measurements were taken with a He-Ne laser light source at 0.63 microm. Since positive eigenvalues were obtained for the coherence matrix, the polarimetric measurements were physically realizable. The anisotropy parameters were determined from the Jones matrices by use of the decomposition theorem. From the M33 and M44 components of the Mueller matrices, it was found that nonspherical structures within the leaf were primarily responsible for observed transmitted light scatter, and spherical structures were mostly responsible for observed backscatter. Variations in backscatter Mueller matrix elements from a fresh leaf to a second day of observation were assumed because of changes to water vapor concentration in the leaf.

Journal Article↗
PubMed2004

Abnoba-viscum (mistletoe extract) in metastatic colorectal carcinoma resistant to 5-fluorouracil and leucovorin-based chemotherapy.

A phase II trial was designed to determine whether mistletoe extract can induce objective tumor response in patients with metastatic colorectal cancer resistant to 5-fluorouracil and leucovorin (5FU/LCV)-based chemotherapy. Twenty-five patients (15 female, 10 male; median age 69 yr) were treated with commercially available mistletoe extract (Abnoba-viscum Quercus) given by three weekly subcutaneous injections with daily dose gradually increased from 0.15 to 15 mg plant extract. Treatment was discontinued if unacceptable toxicity developed or if the patient became bedridden. Median duration of treatment was 14 wk (range, 4-66 wk). Treatment was continued in 14 patients until they became bedridden, and 11 patients decided to discontinue the treatment after their illness progressed. Objective tumor response was not seen in any of the 25 patients (0%, 95% confidence interval 0-13.7%). Stable disease, lasting for a median of 2.5 mo (range, 1.5-7 mo), was noted in 21 (84%) patients. Median survival was 5.5 mo and symptomatic relief was reported by 10 (40%) patients. Toxicity was mild and included mainly local inflammatory reaction. In conclusion, mistletoe extract does not seem to be active in metastatic colorectal cancer resistant to 5FU/LCV in terms of objective tumor response.

Aged↗
PubMed2004

Effect of a lignin-degrading fungus on feeding preferences of Formosan subterranean termite (Isoptera: Rhinotermitidae) for different commercial lumber.

The feeding preferences of the Formosan subterranean termite, Coptotermes formosanus Shiraki, for commercial lumber Alaska yellow cedar, Chamaecyparis nootkatensis (D. Don) Spach; yellow birch, Betula alleghaniensis Britton; northern red oak, Quercus rubra L.; redwood, Sequoia sempervirers (D. Don) Endl; and spruce (Picea spp.) were examined to determine whether the presence of the lignin-degrading basidiomycete Marasmiellus troyanus (Murrill) Singer could alter the relative preference of termites for these wood species. In paired choice tests with fungus-inoculated sawdust versus control sawdust, termites showed a strong preference for the fungus-inoculated sawdust for all wood species tested, except for Alaska yellow cedar. In a multiple-choice test using sawdust without fungus, termites showed a very strong preference for red oak sawdust over the other three species. In a paired choice test using fungus-inoculated sawdust, termites showed a preference for redwood over red oak sawdust. In a feeding test using autoclaved wood blocks without fungal decay, there was no difference in termite consumption of birch, red oak, or redwood. The relative preference of termites for redwood increased when blocks were decayed by M. troyanus for 3 and 8 wk. These results indicate that chemical modifications due to fungal decay affected the feeding preference of termites for different commercial lumber.

Animals↗
PubMed2000

Dogwood borer (Lepidoptera: Sesiidae) infestation of horned oak galls.

Pin oak, Quercus palustris Muenchhausen, is the primary host for the gall wasp Callirhytis cornigera (Osten Sacken). Woody stem galls formed by C. cornigera may be infested by the dogwood borer, Synanthedon scitula (Harris), an important pest of flowering dogwood, Cornus florida L. Previous research has shown that S. scitula has a bimodal seasonal flight pattern, with peaks in late spring and midsummer. We tested the hypothesis that moths emerging from dogwoods largely account for the first flight pulse, whereas emergence from stem galls contributes disproportionately to the second pulse. Seasonal flight activity of S. scitula was monitored with pheromone traps baited with Z,Z-3,13-octadecadien-1-ol acetate. Traps were hung near plantings of dogwoods in suburban landscapes or near heavily galled pin oaks. Borer emergence from dogwood was monitored by sampling infested trees for pupal exuviae, and from galls that were collected and held in outdoor rearing cages. The impact of S. scitula on C. cornigera larvae was assessed by weighing, measuring, and dissecting galls. Flight activity of S. scitula began on 5 May and ended on 13 October 1999, with peaks in late May and in late July to early August. The flight pattern was similar for the two types of trapping sites, and moths emerged from both hosts during both flight periods. Proportionately more moths emerged from dogwoods during the first flight pulse than during the second, but emergence from galls was nearly evenly divided between the two flight peaks. We therefore reject the hypothesis that emergence of borers from galls contributes disproportionately to the second flight period. Approximately 12-15% of stem galls (2-3 yr old) contained S. scitula larvae. Feeding and tunneling by borers contributed to gall desiccation and reduced horn development, but rarely killed C. cornigera larvae. This study has implications for management of S. scitula because borers emerging from horned oak galls may represent a threat to dogwood.

Animals↗
PubMed2001

Nutritional ecology of the formosan subterranean termite (Isoptera: Rhinotermitidae): feeding response to commercial wood species.

The feeding preferences of the Formosan subterranean termite, Coptotermes formosanus Shiraki, were tested in three separate experiments on 28 different wood species. Experiment 1 was a multiple-choice test designed to test relative preferences among 24 wood species commercially available in New Orleans, LA. Experiment 2 was a similar study designed to test relative preferences among 21 wood species shown or reported to be unpalatable to the Formosan subterranean termite. Experiment 3 was a no-choice test to examine the feeding deterrence of the 10 least preferred wood species. Preference was determined by consumption rates. Birch (Betula alleghaniensis Britton), red gum (Liquidambar styraciflua L.), Parana pine [Araucaria angustifolia (Bert.) 1, sugar maple (Acer saccharum Marsh.), pecan (Carya illinoensis Wangenh.), and northern red oak (Quercus rubra L.) were the most preferred species by C. formosanus in order of consumption rate. All of these species were significantly more preferred than southern yellow pine (Pinus taeda L.), widely used for monitoring. Sinker cypress [ = old growth bald cypress, Taxodium distichum (L.)], western red cedar (Thuja plicata Donn), Alaskan yellow cedar (Chamaecyparis nootkatensis D. Don), eastern red cedar (Juniperus virginiana L.), sassafras [Sassafras albidum (Nutt.)], Spanish cedar (Cedrella odorata L.), Honduras mahogany (Swietenia macrophyla King), Indian rosewood (Dalbergia latifolia Roxb.), Honduras rosewood (D. stevensonii Standl.), and morado (Machaerium sp.) induced significant feeding deterrence and mortality to C. formosanus. The last eight species produced 100% mortality after 3 mo.

Animals↗
PubMed2003

Survival and development of Lymantria monacha (Lepidoptera: Lymantriidae) on North American and introduced Eurasian tree species.

Lymantria monacha (L.) (Lepidoptera: Lymantriidae), the nun moth, is a Eurasian pest of conifers that has potential for accidental introduction into North America. To project the potential host range of this insect if introduced into North America, survival and development of L. monacha on 26 North American and eight introduced Eurasian tree species were examined. Seven conifer species (Abies concolor, Picea abies, P. glauca, P. pungens, Pinus sylvestris with male cones, P. menziesii variety glance, and Tsuga canadensis) and six broadleaf species (Betula populifolia, Malus x domestica, Prunus serotiaa, Quercus lobata, Q. rubra, and Q. velutina) were suitable for L. monacha survival and development. Eleven of the host species tested were rated as intermediate in suitability, four conifer species (Larix occidentalis, P. nigra, P. ponderosa, P. strobus, and Pseudotsuga menziesii variety menziesii) and six broadleaf species (Carpinus caroliniana, Carya ovata, Fagus grandifolia, Populus grandidentata, Q. alba, and Tilia cordata) and the remaining 10 species tested were rated as poor (Acer rubrum, A. platanoidies, A. saccharum, F. americana, Juniperus virginiana, Larix kaempferi, Liriodendron tulipfera, Morus alba, P. taeda, and P. deltoides). The phenological state of the trees had a major impact on establishment, survival, and development of L. monacha on many of the tree species tested. Several of the deciduous tree species that are suitable for L. monacha also are suitable for L. dispar (L.) and L. mathura Moore. Establishment of L. monacha in North America would be catastrophic because of the large number of economically important tree species on which it can survive and develop, and the ability of mated females to fly and colonize new areas.

Animals↗
PubMed2001

Distribution, abundance, and habitat preferences of Ixodes ricinus (Acari: Ixodidae) in northern Spain.

Ixodes ricinus (L.) was collected by standard dragging in 2,082 different sites in 18 broad vegetation categories in northern Spain to explore the influence of vegetation on its abundance. Of these, 785 sites were surveyed in 1995, 636 in 1996, and 661 in 1997. The impact of habitat features on differences in tick numbers is addressed. The tick was present in low numbers in areas of old, heterogeneous coniferous forests. Ticks appeared to prefer sites that had substantial secondary plant growth such as river canopies, heterogeneous Pinus uncinata forests, mixed forests, and deciduous heterogeneous woods. Highest tick abundance was recorded for sites that contained Quercus spp., as well as for mixed old forests that had many ecotones. I. ricinus was absent in open habitats, homogeneous young coniferous forests, and open hillsides. These differences were attributed to greater shrub cover and litter depth, which created more favorable microclimatic conditions for tick survival. The abundance of I. ricinus nymphs was not homogeneous in sites within the same habitat category and vegetation physiognomy at these sites did not appear to cause differences in tick abundance. Analysis of variance (ANOVA) indicated that variation in tick abundance could be explained by the exposure of the sampled site, at least for some zones within deciduous forest categories. However, this factor did not explain the variation observed in other habitats. Temperature and vegetation (normalized derived vegetation index) features were recorded daily by remotely sensed imagery throughout the study period and the data were used to obtain long-term mean and maximum values of the physical parameters considered. Multiple regression analysis performed between these long-term abiotic factors and nymphal abundance in positive sites showed high relationship (R2 coefficients) for every habitat category and explained >50% of the variation in tick abundance.

Animals↗
PubMed2006

The influence of aridity and fire on holocene prairie communities in the eastern Prairie Peninsula.

The role of climate and fire in the development, maintenance, and species composition of prairie in the eastern axis of the tallgrass Prairie Peninsula intrigued early North American ecologists. However, evaluation of the long-standing hypotheses about the region's environmental history has been hampered by the scarcity of paleorecords. We conducted multiproxy analyses on early and middle Holocene sediments from two Illinois, USA, lakes to assess long-term climatic, vegetational, and fire variability in the region. Sediment mineral composition, carbonate delta18O, ostracode assemblages, and diatom assemblages were integrated to infer fluctuations in moisture availability. Pollen and charcoal delta13C were used to reconstruct vegetation composition, and charcoal influx was used to reconstruct fire. Results indicate that fire-sensitive trees (e.g., Ulmus, Ostrya, Fraxinus, and Acer saccharum) declined and prairie taxa expanded with increased aridity from 10,000 yr BP to 8500 yr BP. Between approximately 8500 yr BP and approximately 6200 yr BP, aridity declined, and prairie coexisted with fire-sensitive and fire-tolerant (e.g., Quercus and Carya) trees. After approximately 6200 yr BP, prairie taxa became dominant, although aridity was not more severe than it was around 8500 yr BP. Along with aridity, fire appears to have played an important role in the establishment and maintenance of prairie communities in the eastern Prairie Peninsula, consistent with the speculations of the early ecologists. Comparison of our data with results from elsewhere in the North American midcontinent indicates that spatial heterogeneity is a characteristic feature of climatic and vegetational variations on millennial time scales.

Animals↗