Oak-birch Forest Research Articles

Local distribution of ectomycorrhizae-associated basidiomycetes in forest soil correlates with the degree of soil organic matter humification and available electrolytes

Spatial distribution of ectomycorrhizae-associated basidiomycetes was determined in oakbirch forest using terminal restriction fragment length polymorphism (T-RFLP) analysis. The data were correlated with actual soil humidity, pH, electric conductivity of the soil extract, absorbance A(465) and A(665) of water and alkali soil extracts and with the ratio A(465)/A(665) (parameter A4/A6). Natural non-homogeneity of the soil parameters was used as experimental gradient. Distance-based redundancy analysis of the T-RFLP data (with soil parameters being taken as environmental parameters) provided significant results when ITS1F-terminanted restriction fragments were analyzed. Among other fungi, a Mycena galericulata related fungus was observed to correlate negatively with A4/A6, indicating its association with highly humified soil organic matter. Positive association of other, unidentified fungi with A4/A6 was also observed. Several other unidentified fungi negatively correlated with electric conductivity of the soil extract. The results may explain nonhomogeneity of the spatial distribution of the fungi associated with ectomycorrhizae as a result of their interaction with non-homogeneous soil environment.

The chemical composition of throughfall beneath oak, birch and pine canopies in Northwest Germany

The chemical composition of rainwater is altered upon its passage through tree canopies. In order to investigate how rainwater chemistry is affected by canopy-dependent processes in characteristic forest types of Northwest German sandy lowland regions – oak–birch-forests, Betula pubescens Ehrh. swamp forests, and stands of Pinus sylvestris L. – comparative studies on the chemical composition of throughfall were carried out at seven forest sites, situated in close proximity within a nature reserve. Additionally, rainwater was sampled at three heathland sites for analysis of open-field precipitation and at three sites along an oak–birch-forest edge. Throughfall concentrations of most of the parameters analysed were significantly higher than open-field concentrations, especially with regard to electric conductivity, NH4-N, K+, and KMnO4-index. Ion concentrations in throughfall were the lowest in a 10-year-old stand of Betula pendula Roth. and Pinus sylvestris and in a Betula pubescens swamp forest and were highest beneath a stand of Pinus sylvestris. Except for Na+, Cl−, and NO 3 − , ion concentrations in both throughfall and open-field precipitation increased during the growing season (May–October). In throughfall, Ca2+, Mg2+, K+, and Mn2+ were strongly correlated. Enrichment ratios between throughfall and open-field deposition varied among sites and elements and were the highest for K‰+, Mg2‰+, and Mn2‰+. Estimates of canopy leaching indicated high leaching rates of K‰+ and Mn2‰+ and moderate leaching of Mg2‰+. The contribution of foliar leaching to throughfall deposition was higher at the deciduous than at the coniferous stands.

Seasonal and annual variations in soil respiration in a cool-temperate deciduous broad-leaved forest in Japan

We investigated the seasonal and annual variations in soil respiration in a cool-temperate oak–birch forest in central Japan and, in particular, to reveal factors determining seasonal variations in the temperature dependence of respiration based on soil CO 2 efflux data for 1999–2002. The daily soil carbon efflux was moderate in late spring (1.8–2.9 g C m −2 day −1 in May), increased sharply to a peak in summer (4.6–6.0 g C m −2 day −1 in August), and decreased in autumn (1.5–2.5 g C m −2 day −1 in November). In winter, the carbon efflux from the snow surface was low (0.29–0.71 g C m −2 day −1). Soil temperature exerted principle control on the seasonal and annual variation of soil respiration. Furthermore, reduced soil water content decreased soil respiration in summer when droughts occurred. The temperature function driven on a seasonal scale showed large variations in seasonal Q 10 and R 0 (simulated soil respiration at a soil temperature of 0 °C), e.g. a higher Q 10 and lower R 0 in spring and a lower Q 10 and higher R 0 in autumn. These large variations in seasonal Q 10 and R 0 might reflect confounding effects of temperature sensitivity and seasonal changes in physiological activities induced by root phenology, microbial biomass, and other factors. These results suggest that if the objective is to simulate soil respiration in a particular season, a seasonal Q 10 function derived from the target period must be used, especially in a forest ecosystem possessing distinct seasonal changes. Conversely, the annual Q 10 function derived from all measurements of daily soil temperature at −1 cm across the 4 years ( Q 10 = 3.8) was adequate for estimating total annual soil respiration because it may integrate all processes that influence soil carbon efflux, despite the fact it may under- or overestimate daily soil carbon efflux on a seasonal scale. Based on this single annual Q 10 function, the annual mean soil respiration in 1999–2002 was estimated to be 853.5 ± 42.4 g C m −2 without topography correction, and 725.5 ± 36.0 g C m −2 with topography correction for a 1 ha experimental area. The estimated annual soil respiration (1999–2002) gave coefficient of variation (CV) value of less than 10%, suggesting a small inter-annual variability in annual soil respiration during 1999–2002 in this forest, since the annual mean temperature was similar in the 4 years of the survey. Carbon efflux from the snow surface accounted for 10% of the annual soil respiration, with a value of 84.3 ± 7.0 g C m −2, indicating the importance of quantifying winter CO 2 efflux within a forest ecosystem in a cold and snowy region.

Un problème de phytogéographie forestière: la présence de Ceratocapnos claviculata (L.) Lidén dans le nord de la France

Ceratocapnos claviculata (L.) Lidén is an annual acid-tolerant species which distribution area progressively increases thanks to the effects of nitrogen pollution on forest soils. It has been recently discovered in northern France for the first time. This note aims 1) to emphasize the phytogeographical and socio-ecological context of this new station, comparatively to the current european data, 2) to show how forest management may contribute to the plant dispersion in localities far from its area. The plant was found in the herbaceous synusia of a mesotrophic oak-birch forest. It was certainly not spontaneous but the stand is not endangered. Silviculture, through the importation of young pines at the end of the 1970's, should have led to its introduction in Andigny forest. It is now able to essaim in other forests of the region, fulling the large gap of northern France. This case study shows that eutrophication of forest soils is not the only factor which favours the species dispersion.

Increase of biodiversity in homogeneous Scots pine stands by an ecologically diversified management

Three important parameters of biodiversity in first generation Scots pine (Pinus sylvestris) forests on sandy soils have been evaluated: herbal layer diversity, natural regeneration and stand structure. The study took place in the Belgian Campine region, where the original oak–birch forest, degraded to heathlands in the course of time, were finally replaced by monocultures of Scots pine. These first generation pine forests are characterized by a low biodiversity. In maturing stands of this type, however, a spontaneous increase of biodiversity is noticed. Herbal species richness is very limited in all age classes. Different natural regeneration patterns are found. Referring to stand structure, the lengthening of the rotation favours the ingrowth of several hardwood species. As a consequence, the homogenous Scots pine stands are gradually and spontaneously transformed into heterogeneous mixed stands, featuring a noticeable increase in biodiversity. Selected human interventions may further increase biodiversity. The fundamental management principles are discussed: avoidance of major disturbances, lengthening of the rotation period, use of native tree species and natural regeneration, protection of microbiotopes and permanent monitoring.

Evolution of biodiversity in homogeneous Scots pine stands by an ecologically diversified management

This study evaluates three important parameters of biodiversity in first generation Scots pine forests on sandy soils: herbal layer, natural regeneration and stand structure. The research was undertaken in the Belgian Campine Region, where the original oak-birch forest had been destroyed in the course of time and finally been replaced by monocultures of Scots pine. These pine forests are characterised by a low biodiversity. In maturing stands of this type, however, a spontaneous increase of biodiversity is noticed. Herbal species diversity is very limited in all age classes. Spontaneous establishment of Scots pine seedlings is presently a widespread phenomenon in aging stands. Different regeneration patterns are found. Mainly due to the lengthening of the rotation in combination with the ingrowth of several hardwood species, the homogeneous Scots pine stands are gradually and spontaneously transformed into heterogeneous mixed stands, featuring a noticeable increase of biodiversity. Nevertheless, selected human interventions may further increase biodiversity. The fundamental management principles are discussed: avoidance of big disturbances, lengthening of the rotation period, use of native tree species, utilization of natural regeneration, protection of small valuable biotopes and permanent monitoring.

Changes in the composition of rainwater upon passage through the canopies of trees and of ground vegetation in a Dutch oak-birch forest

The composition of canopy throughfall water in an oak-birch woodland, heavily affected by atmospheric deposition of N and S, changed markedly upon contact with the above-ground parts of the ground vegetation, which consisted mainly of bracken. The fluxes of nitrate and H+ decreased, simultaneously with an increase in the flux of bicarbonate, indicative of above-ground uptake of nitrate by the ground vegetation. This above-ground assimilation takes place in spite of abundant availability of inorganic nitrogen in the root zone of the ground vegetation. Fluxes of phosphate were somewhat lower, and those of ammonium somewhat higher in throughfall of the ground vegetation than in that of the tree layer. Although those differences were not statistically significant, they do suggest assimilation of some P and extra net dry deposition of atmospheric ammonia below the tree canopies.

Spore Germination and Microcycle Conidiation of Two Penicillia in Soil

Laboratory-produced spores of two penicillia isolated from soil were placed onto PVC membrane filters, inserted into microholders and buried in the A horizon of an oak-birch forest. After various intervals of time incubation filters were retrieved, stained, and mounted on glass slides for examination. Characteristics of growth and germination of Penicillium daleae and P. bilaii in the laboratory and in the soil were then compared. Spores of these indigenous soil fungi, reinoculated into the soil, germinated slowly, requiring several days for swelling and germ tube protrusion. The most significant observation was the occurrence of a microcycle in which germ tube volume was reduced, mycelial growth was eliminated, and conidiation consisted of a diminution in complexity of reproductive structures by decreasing the number of phialides in the penicillus and reducing spore volume.

Spore Germination and Microcycle Conidiation of Two Penicillia in Soil

Laboratory-produced spores of two penicillia isolated from soil were placed onto PVC membrane filters, inserted into microholders and buried in the A horizon of an oak-birch forest. After various intervals of time incubation filters were retrieved, stained, and mounted on glass slides for examination. Characteristics of growth and germination of Penicillium daleae and P. bilaii in the laboratory and in the soil were then compared. Spores of these indigenous soil fungi, reinoculated into the soil, germinated slowly, requiring several days for swelling and germ tube protrusion. The most significant observation was the occurrence of a microcycle in which germ tube volume was reduced, mycelial growth was eliminated, and conidiation consisted of a diminution in complexity of reproductive structures by decreasing the number of phialides in the penicillus and reducing spore volume. The typical life cycle of imperfect fungi includes germination from a swollen conidium, formation of mycelium, production of reproductive structures, and sporulation. Under certain environmental conditions, however, this is shortened to a microcycle when the mycelial stage is eliminated. These cycles have been demonstrated in vitro for a variety of microorganisms including Aspergillus niger Micheli (Anderson and Smith, 1971), Penicillium urticae Bain (Sekiguchi et al, 1975) and Phomopsis viticola Sacc. (Pezet et al, 1983). Microcycle conidiation is shown in the present study to also occur in soil. The ecological importance of such a system has significant implications to the survival and activity of fungi in this habitat. The study of microcycle conidiation was based on a new method in which spores of two soil penicillia, Penicillium daleae Zaleski and P. bilaii Chalabuda, are reinoculated into the soil on membrane filters in specially designed micro? holders (Gochenaur and Sheehan, 1980). After various periods of incubation in the soil, filters are removed, stained to assess spore viability and examined under the light microscope. Information derived from such a study is critical for predicting the role of microfungi in secondary productivity (Heal and Maclean, 1975) and in estimating the rate of nutrient turnover and substrate mineralization in litter based ecosystems (Dickinson, 1974).

Fungi of a Long Island oak–birch forest. III. Distribution and survival of ascospores in the A horizon

A 1-year survey of soil ascomycetes in the A horizon of an oak–birch forest was conducted using the selective Warcup steaming technique. Fourteen species, including two sclerotial anamorphs, belonging to seven genera were isolated. Their propagules were rare and did not exceed an average of 300 per gram of dry soil, except in the fall when numbers increased fivefold. Only Coniochaeta nepalica and an unidentified Eupenicillium species were isolated at every sampling period. Survival of ascospores of C. nepalica and the coprophilous fungus Sordaria fimicola introduced into the A horizon was tested. Both the indigenous and foreign ascospores showed no loss of viability during 210 days of incubation in soil, but approximately 15% of the Sordaria spores were ruptured as soil particles shifted during freeze–thaw cycles. The latter had no measurable effect on the much smaller ascospores of Coniochaeta.

Fungi of a Long Island Oak-Birch Forest I. Community Organization and Seasonal Occurrence of the Opportunistic Decomposers of the A Horizon

SUMMARY The soil microfungi of the A horizon of an oak-birch forest on Long Island were isolated by dilution plate from 630 soil samples collected over a period of 40 mo. Because these fungi co-occurred in time and space and showed similarities in their nutritional, reproductive, and survival strategies, they are considered a specific community designated the opportunistic decomposers. Dominance in this community was determined by numerical superiority. A discussion of the factors regulating propagule density in soil and a rationale for using propagule density as the quantitative measure of prominence when large numbers of samples are analyzed is presented. Community composition and structure were based upon analysis of 10,684 isolates from 80 samples collected during the spring, summer, fall, and winter of 1975. This assemblage, reduced to 89 taxa, contained four broad-amplitude species; Penicillium terlikowskii, P. daleae, Trichoderma pseudokoningii and Oidiodendron chlamydosporicum?. These species plus Torulomyces lagena, Acremonium diversisporum and Mortierella ramanniana are the characteristic fungi. Seventy-eight percent of the isolates were mycelial Deuteromycetes; the remainder included Zygomycetes and Ascomycetes (6% and 5% of all isolates, respectively) and asporogenous yeasts. Propagules of the opportunistic decomposers were abundant in the A horizon. They remained constant at approximately 340,000 during most of the year but increased to over one million per g dry soil in April. Species diversity was highest in the spring, lowest in the summer, and essentially constant at 16 species per 100 isolates during the other seasons. Stability characterized the community. Particular combinations of species persisted throughout the course of the study resulting in high coefficients of similarity when populations from different years were compared using a modified Sorensen's Index. Seasonal changes in propagule densities for 25 commonly encountered fungi were studied over a 40-mo period. The following patterns were revealed: (1) five species had essentially constant numbers throughout the year; (2) nine increased significantly in the spring; (3) the oidiodendrons showed a winter peak in density; (4) four species, including Beauzeria bassiana and Metarrhizium anisopliae, appeared only in the spring; and (5), five species had apparently random distributions. An attempt was made to correlate some of these patterns with other changes thought to be occurring in the ecosystem a the same time.

Fungi of a Long Island Oak-Birch Forest I. Community Organization and Seasonal Occurrence of the Opportunistic Decomposers of the A Horizon

SUMMARYThe soil microfungi of the A horizon of an oak-birch forest on Long Island were isolated by dilution plate from 630 soil samples collected over a period of 40 mo. Because these fungi co-occurred in time and space and showed similarities in their nutritional, reproductive, and survival strategies, they are considered a specific community designated the opportunistic decomposers. Dominance in this community was determined by numerical superiority. A discussion of the factors regulating propagule density in soil and a rationale for using propagule density as the quantitative measure of prominence when large numbers of samples are analyzed is presented.Community composition and structure were based upon analysis of 10,684 isolates from 80 samples collected during the spring, summer, fall, and winter of 1975. This assemblage, reduced to 89 taxa, contained four broad-amplitude species; Penicillium terlikowskii, P. daleae, Trichoderma pseudokoningii and Oidiodendron chlamydosporicum?. These species plus Torulomyces lagena, Acremonium diversisporum and Mortierella ramanniana are the characteristic fungi. Seventy-eight percent of the isolates were mycelial Deuteromycetes; the remainder included Zygomycetes and Ascomycetes (6% and 5% of all isolates, respectively) and asporogenous yeasts. Propagules of the opportunistic decomposers were abundant in the A horizon. They remained constant at approximately 340,000 during most of the year but increased to over one million per g dry soil in April. Species diversity was highest in the spring, lowest in the summer, and essentially constant at 16 species per 100 isolates during the other seasons. Stability characterized the community. Particular combinations of species persisted throughout the course of the study resulting in high coefficients of similarity when populations from different years were compared using a modified Sorensen's Index.Seasonal changes in propagule densities for 25 commonly encountered fungi were studied over a 40-mo period. The following patterns were revealed: (1) five species had essentially constant numbers throughout the year; (2) nine increased significantly in the spring; (3) the oidiodendrons showed a winter peak in density; (4) four species, including Beauveria bassiana and Metarrhizium anisopliae, appeared only in the spring; and (5), five species had apparently random distributions. An attempt was made to correlate some of these patterns with other changes thought to be occurring in the ecosystem a the same time.