Oak-beech Forest Research Articles

Effects of forest management on bird assemblages in oak-dominated stands of the Western Carpathians – Refuges for rare species

Forest management practices have varying impacts on biodiversity because the treatments and their outcomes do not always reflect the natural processes that maintain biodiversity. These management activities can be assessed using indicator species, among which birds are most frequently used. In 2018 we compared bird assemblages in oak (Quercus spp.)-dominated forests with admixtures of European beech (Fagus sylvatica), hereafter referred to as oak-beech forests, between managed and natural forest stands on opposite sides of the Carpathian range (south-facing in Slovakia and north-facing in Poland). The aim was to quantify and model the relationships between the quantitative parameters of bird assemblages and the main habitat parameters, as influenced by differing intensities of forest management. The point-count method with limited distance was applied to census birds (N = 100). Overall forest bird assemblages were found to be similar in respect to diversity indexes in managed and protected areas, as well as between southern and northern slopes of the Western Carpathian range, but all these types of forest differed in respect to bird species composition. However, both geographic location and management intensity, altogether with forest complexity contributed the mostly in explanation of bird diversity. The greatest differences were recorded for rare species, particularly those annexed in the Birds Directive of the European Union (mainly woodpeckers and flycatchers), as these birds were found either exclusively or in much greater numbers in nature reserves. Management intensity, forest complexity, and topography best explained the diversity of rare birds. Silvicultural systems applied in management of the Carpathian oak-beech forests, particularly the shelterwood system, seem to be sufficient for the preservation of overall bird diversity. However, decreased forest fragmentation and increased deadwood amounts are necessary measures to provide more close-to-nature stand structures, which will help support higher diversity of most bird species associated with mature forests. Because the oak-beech forests comprises only about 15% of the total forest area in the Western Carpathians, creating a network of natural or close-to-nature forest patches is recommended for the conservation of forest birds (and whole forest communities), including species annexed in the Birds Directive. Conservation priorities should be focused mainly in areas of harsh topography, where reduced wood production in these forests would have a less detrimental effect on the local forestry communities. These actions should also greatly improve the nature conservation system in the Carpathians and more generally throughout Central Europe.

The effect of tree diversity on the resistance and recovery of forest stands in the French Alps may depend on species differences in hydraulic features

As climate change should lead to an increase in the vulnerability and the sensitivity of forests to extreme climatic events, quantifying and predicting their response to more severe droughts remains a key task for foresters. Furthermore, recent works have suggested that tree diversity may affect forest ecosystem functioning, including their response to extreme events. In this study we aimed at testing whether the growth response of forest stands to stressful climatic events varied between mixed and monospecific stands, under various environmental conditions. We focused on beech-fir forests (Fagus sylvatica [L.] and Abies alba [L.]) and beech-oak forests (F. sylvatica [L.] and Quercus pubescent [L.]) in the French Alps. We used a dendrochronological dataset sampled in forest plots organized by triplets (one mixture and two monospecific stands) distributed in six sites along a latitudinal gradient. We tested (1) whether stand diversity (two-species stands vs monospecific stands) modulates the stands’ response to drought events in terms of productivity, (2) whether species identity may drive the diversity effect on resistance and recovery, and (3) whether this can be explained by interspecific interactions. We found that (1) interspecific differences in response to extreme drought events (possibly due to interspecific differences in hydraulic characteristics) can induce a mixture effect on stand growth, although it appeared (2) to be strongly depending on species identity (positive effect only found for beech-fir mixed stands), while (3) there were no significant non-additive effects of diversity on stand resistance and recovery, except for some specific cases. Overall, our study shows that promoting selected mixed stands management may buffer extreme drought effect on stand productivity.

Labile soil organic matter changes related to forest floor quality of tree species mixtures in Oriental beech forests

Abstract Labile soil organic matter, which is an important supply of energy for soil micro-organisms, has been suggested as a sensitive indicator of soil organic matter (SOM). In this study, the effects of forest vegetation on forest floor thickness and quality, labile SOM fractions and soil properties were examined in five different forest ecosystems, such as beech-hornbeam-alder, beech-hornbeam, beech-alder, beech-oak, and pure beech in the Hyrcanian region, northern Iran. Each forest type was replicated three times. In each plot, six forest floors and soil samples were taken in a 30 × 30 cm area. Pure beech had always a higher forest floor thickness than the other studied forest types. Increase in tree diversity in beech forest type reduced forest floor C:N ratio, more than three-fold, compared to pure beech. Based on our data, the influence of forest type on labile SOM was generally higher in the 0–10 cm soil layer than in the 10–20 cm layer. Beech-hornbeam-alder and beech-alder forest types, with high quality of forest floor and more values of N fractions in labile SOM, increased soil biological activities and fertility whereas pure beech and beech-oak forest types, with lower quality of forest floor and more values of C fractions in labile SOM reduced soil biological activities and fertility. Based on the result, the abundance of beech influenced nutrient cycling via forest floor quality. This led to an increase in labile SOM and subsequent soil fertility through the admixture of broadleaf species into beech forests.

Trajectory from beech and oak forests to eastern broadleaf forests in Indiana, USA

BackgroundHistorical forests (circa 1799 to 1846) of Indiana were predominantly composed of American beech (25% of all trees) and upland oaks (27% of all trees). I compared historical forest composition, using studies of smaller areas to approximate composition for uncommon species or genera (< 4.5% of all trees) and forest types, to current forest composition and forest types in Indiana. I also compiled published historical density estimates from small studies and estimated current density for the state.ResultsCurrent forests are diverse with an even composition of many eastern broadleaf species. In addition to upland oaks, which decreased to 13% of all trees, only sugar maple currently comprises greater than 10% of all trees. Other increasing species were yellow-poplar, red maple, black cherry, and eastern redcedar. Eastern redcedar increased from no presence to one of the most abundant ten species (≥ 3.5% of composition), similarly to the pine genus, becoming more common currently than American beech. Beech or oak or beech-oak forest types (≥ 24% of all trees) became eastern broadleaf forests, with no dominant species, and black cherry, red maple, and eastern redcedar forest types now occurred. Estimates of historical oak or beech forests ranged from 28 trees per hectare to 175 trees per hectare, which probably represent savannas and woodlands. Current mean density of Indiana forests is 385 trees per hectare, ranging from 180 trees per hectare to 450 trees per hectare. These forests likely contain dense layers of woody vegetation, filling the midstory and replacing herbaceous vegetation in the ground layer.ConclusionHistorically dominant beech and oak forests in the eastern United States have transitioned to an alternative state of closed eastern broadleaf forests due to uncontrolled establishment of many tree species.

Fruiting Body Production of, and Suitable Environmental Ranges for, Growing the Umbrella Polypore Medicinal Mushroom, Polyporus umbellatus (Agaricomycetes), in Natural Conditions in Central Europe.

This article presents the ecological distribution of the edible and medicinal mushroom Polyporus umbellatus in Central Europe. Our main motivation is to describe the potential for commercial cultivation of this species. All data considered in this study are based on records from 70 localities in Slovakia. Fruiting bodies and sclerotia have been recorded in forests in which beech, hornbeam, and oak dominate, at altitudes ranging from 150 to 935 m (mean altitude, 403 m). In Slovakia, these areas correspond to warm, hilly, and upland beech-oak and oak-beech forests. Mean annual air temperature between 6°C and 9°C characterizes about 94% of the areas. Continuous monitoring of fruiting body production at 13 plots showed peak growth in August. In total, 192 fruiting bodies were recorded over a 5-year period. P. umbellatus predominantly grows in acidic soils (pH 4.5-4.99), with no individuals found in soils with pH above 7.0. Our findings can be used for growing the fungus and expanding its growth to new regions, not only in Central Europe.

Drought modifies tree competitiveness in an oak-beech temperate forest

Over recent decades, forest management in Europe has increasingly moved towards the emulation of natural dynamics. Natural dynamics in beech-oak forests leads to the formation of monospecific beech stands, the oak usually being excluded or restricted to sites with poor growing conditions. However, beech is more vulnerable than oak to drought and high temperatures. In this study, we examine whether climate change could attenuate the dominance of beech and improve the competitive capacity of oak in an old-growth temperate forest located in the “Picos de Europa” National Park, northern Spain. We used a dendroecological approach to reconstruct the competitive capacity of beech and oak and developed a projection for the 21st century based on forecasted climate conditions under three different emission scenarios. Beech is the dominant tree species in the studied forest, where the disturbance regime has favored the replacement of oak by beech. In general oaks are older than beeches and most of the small trees are beeches. Our results show that this substitution process may weaken due to the vulnerability of beech to warmer and drier conditions. Climate change will benefit oak growth over beech over the course of the 21st century, as was observed in the late 20th century. However, the natural gap dynamic benefits beech due to its greater shade-tolerance. Therefore, if the resilience of the ecosystem is to be increased, management strategies favoring oak regeneration are necessary given the better adaptation of oak to climate change.

ЕКОЗБАЛАНСОВАНЕ ГОСПОДАРЮВАННЯ У СМУЗІ ДУБОВИХ І БУКОВИХ ЛІСІВ ЗАКАРПАТТЯ

Розглянуто поняття сукцесії та генези лісостанів. Викладено питання лісової типології з позицій забезпечення стабільності природного відбору в популяціях деревних видів та відповідного ведення лісового господарства. Проаналізовано особливості популяційного підходу до екозбалансованого лісогосподарювання. Підхід базується на тотожності сукцесійного і популяційного процесів лісостанів у просторі й часі. Розглянуто питання сукцесійних змін лісостанів для грабово-букових та дубово-букових типів лісу Закарпаття. Рекомендуючи лісовідновлення з використанням природного поновлення, формування насаджень розглянуто з лісокультурних позицій, для яких придатнішою є еколого-лісівнича типологія. Генезисний ряд об'єднано за типами лісорослинних умов для ведення певного типу лісового господарювання (гірське лісівництво, екологічно орієнтоване чи лісоексплуатаційне), які передусім враховують лісоексплуатаційний аспект та відповідне лісовідновлення. Популяційний підхід на типологічній основі дасть змогу прив'язати ці загальні положення до певних гірських територіальних комплексів. Для вирішення питання щодо поєднання результатів біологічних та екологічних досліджень в лісознавчу парадигму на типологічних засадах запропоновано сукцесію, як стадійний процес, розглядати в контексті розвитку типу лісу, його генези відповідної класифікації за стадіями.

Tree species effects are amplified by clay content in acidic soils

The tree species composition of many forests in western and central Europe has changed considerably over the last century, as large areas of mixed deciduous forests were replaced by conifer plantations. In this study, we aim to evaluate whether conversion of mixed broadleaved forest to Norway spruce (Picea abies) on the acidic soils of the Gaume forest (southern Belgium) affected soil quality in terms of soil acidity, exchangeable calcium and aluminium, humus type and earthworm communities, and determine whether this effect is mitigated or amplified by an edaphic gradient in clay content. In this ancient deciduous woodland, stands were partly converted from mixed deciduous forest to Norway spruce monocultures 30–60 years ago. A twin-plot setup was established, where we sampled pairs of adjacent deciduous and Norway spruce plots along a gradient in clay content varying between 3 and 34%. This design allowed to evaluate the effects of soil type and conversion independently. In the deciduous plots, forest type ranged from mixed oak-hornbeam forest to oak-beech forest. The first has a higher clay content, higher exchangeable calcium, mull humus type, low forest floor mass and the presence of burrowing earthworms (endogeics), while the latter is characterised by high forest floor mass and presence of only litter-dwelling earthworms (epigeics), respectively. Our results provide evidence that the natural biogeochemical gradient converges to a narrow and acid range after conversion. When comparing Norway spruce plots with adjacent broadleaved stands, topsoil pH, calcium concentrations and total earthworm biomass were significantly lower, endogeic and epi-anecic earthworms were mostly absent, and the exchangeable aluminium was significantly higher. Contrary to the current paradigm, the impact of conversion in these acidic soils is largest for the stands with the highest clay content, where the larger exchange capacity allows greater accumulation of exchangeable aluminium when pH becomes sufficiently low. These findings have important implications for forest management: for systems near a threshold in soil process domain, it is important to realise that the sites with higher CEC and more favourable pH-values are the ones that will have larger trajectories and deteriorate the most upon acidification. Hence restoring such stands into more natural deciduous or mixed forest may become increasingly difficult.

Change in biomass of an old-growth beech-oak forest of Mt. Hakusan over a 17-year period

Change in biomass of an old-growth beech-oak forest of Mt. Hakusan over a 17-year period

Habitat preferences of Hericium erinaceus in Slovakia

Distribution patterns, ecology and habitats of Hericium erinaceus in Slovakia are presented, together with an indication of its population size and dynamics as driven by the type of substratum the fungus feeds on. Basidiomata have been recorded both on living and dead trees, predominantly on oaks (Quercus spp.) but also on European beech (Fagus sylvatica), and at altitudes ranging from 103 to 753 m, which in Slovakia corresponds to warm hilly and upland beech-oak forests. Standing trunks were a more common substratum than fallen trunks. Although the fungus tends to occur in old-growth forests, nearly half of the observations were from managed forests. Given the observed distribution, we conclude that H. erinaceus is not a strict indicator of intact old-growth forests in Slovakia.

Density-dependent responses in some common lumbricid species

It is generally accepted that populations of most species experience some level of density dependence; however, this has rarely been shown for soil-dwelling invertebrate species, in particular for earthworms. Experimental data, mostly obtained at high laboratory densities, suggest intense intraspecific competition for resources and/or living space and density-dependent dynamics in earthworm populations, irrespective of their ecological group affiliation. In the present study performed in large field microcosms, I investigated whether density-dependent responses occur within the earthworm density gradients more realistic for the natural sites. Five lumbricid species from epigeic (Dendrobaena octaedra, Lumbricus rubellus), endogeic (Allolobophora chlorotica, Aporrectodea caliginosa) and anecic (Lumbricus terrestris) ecological groups were tested. Soil systems populated with earthworm monocultures in large (20-L) microcosms were exposed in a beech-oak forest for 4.5 months; each species was represented by two (L. terrestris) or three treatments forming gradients of increasing density. In two endogeic species, manifold and generally similar density-dependent responses (a retardation of growth, maturation and reproduction rates, but higher mortality rates with density increase) were revealed, likely explained by spatial competition rather than by direct food competition. In each of epigeic species density-dependent responses were less variable and more species-specific. In contrast to endogeics, direct food competition was presumably a more important cause of density-dependence. In L. terrestris no significant density-dependent responses in adult earthworms were revealed; however, they need to be further investigated in relation to the age and territorial behaviour of individual earthworms. Importantly, in any earthworm species the density variations in the reproducing generation had significant consequences for the advancing generation, affecting either the numbers or/and the size (individual weight) of the cocoons produced. It is suggested that an underestimation of density-dependent processes may cause inaccurate estimates of the activities of local lumbricid populations.

Stocks and dynamics of soil organic carbon and coarse woody debris in three managed and unmanaged temperate forests

The effect of forest conservation on the organic carbon (C) stock of temperate forest soils is hardly investigated. Coarse woody debris (CWD) represents an important C reservoir in unmanaged forests and potential source of C input to soils. Here, we compared aboveground CWD and soil C stocks at the stand level of three unmanaged and three adjacent managed forests in different geological and climatic regions of Bavaria, Germany. CWD accumulated over 40–100 years and yielded C stocks of 11 Mg C ha−1 in the unmanaged spruce forest and 23 and 30 Mg C ha−1 in the two unmanaged beech–oak forests. C stocks of the organic layer were smaller in the beech–oak forests (8 and 19 Mg C ha−1) and greater in the spruce forest (36 Mg C ha−1) than the C stock of CWD. Elevated aboveground CWD stocks did not coincide with greater C stocks in the organic layers and the mineral soils of the unmanaged forests. However, radiocarbon signatures of the Oe and Oa horizons differed among unmanaged and managed beech–oak forests. We attributed these differences to partly faster turnover of organic C, stimulated by greater CWD input in the unmanaged forest. Alternatively, the slower turnover of organic C in the managed forests resulted from lower litter quality following thinning or different tree species composition. Radiocarbon signatures of water-extractable dissolved organic carbon (DOC) from the top mineral soils point to CWD as potent DOC source. Our results suggest that 40–100 years of forest protection is too short to generate significant changes in C stocks and radiocarbon signatures of forest soils at the stand level.

Dendroecological reconstruction of disturbance history of an old‐growth mixed sessile oak–beech forest

AbstractQuestionsWhat are the stand development patterns and successional processes occurring in a Quercus petraea–Fagus sylvatica old‐growth forest? Do these two sympatric species have different recruitment and canopy accession strategies? How do they respond to disturbance?LocationOld‐growth Q. petraea–F. sylvatica forest in Runcu Grosi Natural Reserve, Romania.MethodsIncrement cores were taken from 110 similarly sized pairs of standing dead and living sessile oak trees, and additionally from the 110 most competitive neighbouring living beech trees, growing in the best‐preserved part of the reserve. Release events were detected using the boundary line method. Recruitment and canopy accession strategies were defined using tree juvenile growth rate, overall growth patterns and the presence or absence of a major crown release.ResultsSessile oak establishment occurred between 1800 and 1859, while beech have regenerated continuously, with greater in‐growth after 1860. Tree recruitment followed species‐specific requirements, with most sessile oak having a gap origin (82%) and many beech regenerating in the understorey (41%). Release events occurred continuously during the period analysed (1820–2003), but the percentage of trees per decade that showed releases was &lt;15%. A larger number of releases were recorded in beech compared to sessile oak. Living and dead sessile oak originated under similar conditions, but after the 1900s they experienced different canopy disturbances regimes.ConclusionsThe investigated stand appears to originate after a large‐scale disturbance that promoted sessile oak recruitment. Thereafter, regular small‐scale disturbances favoured beech, which became a competitor to sessile oak and achieved faster growth despite a less favourable initial canopy position. Mortality started to occur in oak. Stand maturation and increasing competition could favour the occurrence of large‐scale windthrow, which would again promote sessile oak.

Impact of interacting bark structure and rainfall conditions on stemflow variability in a temperate beech-oak forest, central Germany

ABSTRACTTrees concentrate rainfall to near-stem soils via stemflow. When canopy structures are organized appropriately, stemflow can even induce preferential flow through soils, transporting nutrients to biogeochemically active areas. Bark structure significantly affects stemflow, yet bark-stemflow studies are primarily qualitative. We used a LaserBark to compute bark microrelief (MR), ridge-to-furrow amplitude (R) and slope (S) metrics per American Society of Mechanical Engineering standards (ASME-B46.1–2009) for two morphologically contrasting species (Fagus sylvatica L. (European beech), Quercus robur L. (pendunculate oak)) under storm conditions with strong bark water storage capacity (BWSC) influence in central Germany. Smaller R and S for F. sylvatica significantly lowered BWSC, which strongly and inversely correlated to maximum funnelling ratios and permitted stemflow generation at lower rain magnitudes. Larger R and S values in Q. robur reduced funnelling, diminishing stemflow drainage for larger storms. Quercus robur funnelling and stemflow was more reliant on intermediate rain intensities and intermittency to maintain bark channel-dependent drainage pathways. Shelter provided by Q. robur’s ridged bark also appears to protect entrained water, lengthening mean intrastorm dry periods necessary to affect stemflow. Storm conditions where BWSC plays a major role in stemflow accounted for much of 2013’s rainfall at the nearest meteorological station (Wulferstedt).Editor M.C. Acreman; Associate editor not assigned

The first contribution to the fauna of psocids (Insecta: Psocoptera) in forests in the Drahanská vrchovina Hills (Czech Republic)

Taxocenosis of psocids (Psocoptera) was studied in the territory of the DrahanskĂĄ vrchovina Hills in the Czech Republic. Representative research plots were selected in forest ecosystems with natural species composition and spatial structure (small-scale strictly protected areas) as well as in forest ecosystems with altered tree species composition and spatial structure. Research was conducted in three altitudinal vegetation zones (AVZ): in 2nd communities of Fagi-querceta s. lat. (beech-oak forests), 3rd Querci-fageta s. lat. (oak-beech forests) and 4th Fageta abietis (beech forests with fir). Research plots are situated at altitudes ranging between 275 and 540 m a.s.l. In the 2013 growing season, totally 3,474 imagoes and 2,532 nymphs of 32 psocid species were collected. Of those, 748 imagoes of 25 psocid species were collected in Fagi-querceta. The occurrence of Caecilius burmeisteri, Caecilius flavidus and Graphopsocus cruciatus was eudominant. 2,194 imagoes of 23 psocid species were found in Querci-fageta, eudominant were there Caecilius flavidus and Caecilius burmeisteri. 532 imagoes of 18 psocid species were found in Fageta abietis, eudominant were there: Caecilius flavidus, Peripsocus subfasciatus and Caecilius burmeisteri. In respect to the species composition, 3rd AVZ and 4th AVZ are similar to each other while 2nd AVZ is less similar.

The Response of Basal Area Increment in Old Sprout-origin Sessile Oak (Quercus petraea (Matt.) Liebl.) Trees During Their Conversion to a Coppice-with-standards

This paper addresses the response of adult sprout-origin sessile oaks (Quercus petraea(Matt.) Liebl.) to a strong release. Our research plot was established at the Training Forest Enterprise of Mendel University in Brno (Czech Republic) at the turn of 2008/2009. The plot is situated on a plateau with mesotrofic soil in a beech-oak forest vegetation zone at an altitude of 410 m above sea level. Tree responses were monitored using precise girth measurements. During the first year after the release, the basal area increment showed a positive correlation with only the tree diameter. During the second and third year, the basal area increment was also correlated with the release intensity. During the third year, the basal area increment was explained by the tree diameter, the crown shape, and the release intensity as well as individual types of epicormic shoot occurrence. The occurrence of epicormic shoots in the lower part of the trunks and umbel-shaped crowns increased the basal area increment. In the first, second and third year after thinning, the model explained 11.79%, 11.25% and 28.99%, respectively, of the basal area increment variability. Adult trees of sprout origin responded to a strong release very early (within two years) after felling.

Effect of land use on the carbon and nitrogen forms in humic horizons of Stagnic Luvisols

The aim of the study was to assess the effect of land use on the forms of carbon and nitrogen in humic horizons of Stagnic Luvisols located in the area of Slawienska Plain (northern Poland). Soil samples were collected form six stands with different land uses located in the same soil complex: more than 100-year-old beech-oak forest (BOF), meadow (M), arable field (AF), fallow (F), secondary afforestation with 15- year-old birch trees (SAB) and secondary afforestation with 30-year-old alder trees (SAA). In every stand, soils were sampled in five replications and analyzed with standard methods used in soil science. The content of different forms of carbon and nitrogen was analyzed after sequential extraction in 0.25 mol KCl dm-3, 0.25 mol H 2 SO 4 dm-3 and 2.5 mol H 2 SO 4 dm-3 (Becher, KalemBasa 2011). Different land uses were reflected in the properties of humic horizon of the investigated soils. Particularly large differences were observed between the forest soils never used for agriculture, and arable or post-arable soils. Tillage caused the increase of the A horizon depth from 9.2 to 26.4-35.6 cm, and the increase of its volumetric density. The highest content of soil organic matter (SOM), total organic carbon (TOC) and total nitrogen (TN) as well as the highest TOC:TN ratio were observed in BOF stand. Statistically significant differences were observed between the stands in the content of carbon forms. Nonhydrolyzable carbon was dominat in the soils (55.98-68.11% of TOC), and dissolved organic carbon (DOC) had the smallest contribution (1.43-3.70% in TOC). In general, higher contribution of DOC in TOC was observed in arable and post-arable soils than in soils under forest. The content of mineral nitrogen (NO 3 -N + NH 4 -N) in the studied soils ranged from 0.028 to 0.053 g kg -1 , and NH 4 -N dominated in the pool. The lowest concentration of mineral nitrogen was observed in arable soils, and significantly higher in the soils under forest and fallow. Easily hydrolyzable nitrogen (EHN), weakly hydrolyzable nitrogen (WHN) and nonhydrolyzable nitrogen (NHN) were the main forms of the element in the studied soils and their content was closely related to the content of SOM. The highest concentration of the forms was noticed in BOF stand. There were differences between the stands in DOC:DON, EHC:EHN, WHC:WHN and NHC:NHN ratios, which indicate varied biological activity of the soils under different uses.

Relating changes in understorey diversity to environmental drivers in an ancient forest in northern Belgium

Background and aims - A renewed interest in the functional role and dynamics of forest understorey plant communities has lead to an increasing number of publications that present the results of understorey resurveys. However, studies looking at the possible causes of temporal changes in the understorey often lack data on soil and tree layer conditions for the old survey. We investigated how changes in the tree layer, soil, and understorey were related in two contrasting forest types. Methods - Full re-inventory of the tree layer (1997, 2010) and resurvey of the soil and understorey in 40 plots on a permanent grid (1993, 2011) in an ancient temperate deciduous forest. The 1.83 ha study area consisted of a part dominated by oak (Quercus robur) and beech (Fagus sylvatica) and a part dominated by ash (Fraxinus excelsior). Key results - Overall, the basal area and shade-casting ability of the tree layer had increased. In the oak-beech forest, the soil pH had decreased; below ash, the topsoil pH had increased. The understorey species richness had increased, and the change in species richness was correlated with the change in soil pH and basal area, the latter in the oak-beech forest only. The observed patterns in understorey dissimilarity were different for the dataset including or excluding the regeneration of woody species. Conclusions - The changes in soil and understorey differed between the two forest types, and there were some indications of recovery from soil acidification in the ash forest.

The efficiency of pitfall traps as a method of sampling epigeal arthropods in litter rich forest habitats

Pitfall trapping is an approved self-sampling method for capturing epigeal arthropods for ecological and faunistic studies. Capture efficiency of pitfall traps may be affected by external factors and the design of the trap. Pitfall traps set in forests are usually protected with covers or wire grids, but the effect of these constructions on sampling efficiency as well as their practicability and necessity have so far received little attention. During the present study pitfall traps of four different designs (covers, wire grids, litter exclosure, open) were tested in terms of their efficiency in capturing ground-dwelling arthropods (Acari, Araneae, Carabidae, Formicidae, Isopoda, Myriapoda, Opiliones) in order to gain a better understanding of the applicability and reliability of pitfall traps in forests. The study was carried out in an oak-beech forest in Northwest Germany using a total of 40 pitfall traps (ten replicates per trap design). Generalised linear models indicated no significant differences in arthropods counts among catches of pitfall traps of the four different designs, except for woodlice. Ordination analyses (NMDS) and MANOVA revealed no significant differences in spider and carabid beetle species compositions of the catches. In contrast, for both these taxa there were significant differences in the body sizes of the individuals caught. We conclude that the catches of pitfall traps are little affected by their design. Furthermore, the litter layer and litter input have no effect on the capture efficiency and thus there seems to be no need to protect pitfall traps with covers or wire grids in litter rich forest habitats.

Phytocenological and edaphic characteristics of sessile oak forests on Miroc Mt in northeastern Serbia

This research was carried out in natural stands of sessile oak (Quercus petraea agg. Ehrendorfer 1967) on Miroc mountain. Three comunities were investigated: Pure sessile oak forest (Quercetum montanum Cer. et Jov. 1953. s.l.), sessile oak-common hornbeam forest (Querco-Carpinetum moesiacum Rud. 1949. s.l.) and sessile oak-balkan beech forest (Querco-Fagetum Glis. 1971). Pure sessile oak forests are found on the following soils: dystric ranker and acid cambic soil on sandstone, dystric ranker and acid cambisols on phyllite, and acid cambic soil on schists. Sessile oak-hornbeam forests grow on sandstone, granite and schists. Sessile oak-beech forests are found on acid cambisol on phyllite and sandstone conglomerate. Various ecological conditions (exposition, slope, altitude, soil types and bedrock) on Mt Miroc caused the occurence of diverse sessile oak forest communities, while different states of these forest stands resulted from the implementation of management measures.