Species deletion in Potentillo albae-Quercetum phytocoenoses reversed by the removal of Carpinus betulus

The studies were conducted in the Biaowiea primeval forest on a study area of 28,000 m², divided into two plots and 280 quadrats. In 1979, all Carpinus betulus individuals were cut off within the experimental plot (E, 7800 m²), whilst the control plot (C, 13000 m²) remained unchanged. Each plot contained a phytocoenose of Potentillo albae-Quercetum and an adjacent community of Tilio-Carpinetum.By 1983, hornbeam invasion into the oak-forest habitat within C plot had resulted in: 1) a decrease in species number by more than 10 per 100 m² on average (c.a. 30%); 2) a twofold greater deletion rate of heliophil oak-forest species than for Fagetalia and Querco-Fagetea; 3) a diminution of the area of oak-forest phytocoenose by more than 100 m² per year; 4) formation of a community with a species combination corresponding to Tilio-Carpinetum. Hornbeam removal had the opposite effect: 1) the number of species increased by more than 100%; 2) the number and frequency of oak forest species rose considerably; 3) those parts of the phytocoenose colonized previously by Carpinus betulus regenerated, and thence the area of Potentillo albae-Quercetum community increased.     

Predicting the distribution of Carpinus betulus in Denmark with Ellenberg's Climate Quotient

In this paper we investigate whether Ellenberg's Climate Quotient (EQ, defined as the mean temperature of the warmest month divided by annual precipitation, multiplied by IOOO), can be used to predict the distribution of Carpinus betulus in Denmark. It has been suggested that the competitive relationship between the two tree species Fagus sylvatica and C.betulus is related to EQ in central Europe. Areas with low EQ have dominance of E. sylvatica, whereas higher EQs are associated with dryer and warmer climates that favour C.betulus. To determine if this holds true, also in northern Europe, we investigate the present distribution of C.betulus in Denmark, based on a comprehensive dataset with presence-absence information of the species. We relate the distribution of C.betulus to 12 climate parameters and indices (including EQ), analyse it in a geographical information system and compare the ecology of C.betulus and E sylvatica in four Danish forests, located in different climatic and floristic regions. The highest density of C.betulus was found in eastern Denmark where EQ is high, i.e. summer temperature is relatively high and precipitation low. In the western and south-western parts of the country, where the climate is slightly more wet and more oceanic, there are fewer populations of C.betulus. Based on present climatic data it seems that the climate of Denmark does not limit the occurrence of C.betulus, except perhaps for a small area in western Jutland. We believe that climate changes in the late Holocene cannot alone account for the changes in the distribution of C.befulus in Denmark. And future climate change is likely to affect the distribution of C.betulus with generally better conditions.     

The relation between vegetation and soil chemistry gradients in a ground water discharge fen

Abstract. The soil chemistry of a headwater valley fen is influenced by local ground water discharge that supplies base cations and alkalinity to the fen. An irrigation canal just upward of the fen is the source of this alkalinity. The ecological consequences of this artificial system are studied both on the soil and vegetation level. Rich-fen species of the alliance Caricion davallianae are connected to soil water alkalinity and soil base status. They depend directly on the alkaline ground water discharge. In addition, the local input of this water causes a gradient-rich pattern from poor to rich fen, and it is therefore concluded that it is responsible for the presence of intermediate fen vegetation too. High nutrient levels in the irrigation water have not influenced the fen until now. This case study illustrates the possibility for rich fen restoration after acidification. Irrigation with alkaline water is efficient if excess nutrients can be removed.     

Local and regional trends in the ground vegetation of beech forests

We sampled moss and vascular forest vegetation in five ancient beech forests from northwest France, embracing in each a wide array of environmental conditions. Indirect (PCA) and direct (RDA) gradient analysis were used to discern local and regional ecological factors which explain the observed variation in species composition. Our results point to a global factor encompassing a large array of soil and light conditions, unravelled when local particularities of studied forests are singled out. The humus form, numerically expressed by the Humus Index, explains a large part of the observed variation in ground vegetation. Our study confirmed opposite trends in vascular and moss species richness according to humus condition. Ecological factors to which vascular and moss forest species respond at the regional level can be estimated directly in the field by visually inspecting humus forms and vegetation strata despite of the confounding influence of local factors.     

Competition between Quercus petraea and Carpinus betulus in an ancient wood in England: seedling survivorship

Abstract. Age structures of populations of canopy trees in Wormley Wood are consistent with reports that successional change is occurring, with Carpinus betulus replacing Quercus petraea as the dominant species. TWINSPAN analysis of data from a vegetation survey identifies three communities (described in earlier work), the ‘Bracken’, ‘Bramble’, and‘Bareground’ societies, characterized by increasing prominence of C. betulus and loss of species diversity. An experiment was set up in which C. betulus, Q. petraea and Betula pendula seedlings were explanted into each of the communities. Survival of seedlings was monitored over 860 days and differences investigated. Cohort survivorship differed between species and sites. C. betulus seedlings survived longer than Q. petraea in Bracken and Bramble communities. Species- and site-specific variation in the types and effects of herbivory were found. Herbivory did not appear to be a critical factor in the survival of Q. petraea seedlings. The photosynthetic light response of the seedling species was measured in the field. The light compensation point for Q. petraea seedlings (77 μmol photon m^-2 s^-1) is higher than the maximum available light under the main tree canopies in the wood. In contrast, seedlings of C. betulus have a lower light compensation point (15 μmol photon m² s^-1) and the mature tree casts a deeper shade than Q. petraea. It is suggested that the invasion of the canopy by C. betulus, following the cessation of coppicing, is creating light levels too low for Q. petraea seedling banks to persist.     

Regional differences in floristic change in South Swedish oak forests as related to soil chemistry and land use

Abstract. Changes of the ground layer vegetation between 1983 and 1993 were studied on permanent oak forest plots in Skåne and eastern Småland, two regions of South Sweden rich in oak but with different climatic conditions. 79 of the 123 more common species differed considerably in frequency between Skåne and Småland. The oak forests in Skåne contained more typical forest species, whereas the number of light-demanding grassland species was higher in Småland. Almost half of the more common species showed significant changes in frequency between 1983 and 1993. Several species of clearings and some light-demanding grassland species increased their frequency in Skåne. They were probably favoured by canopy thinning which occurred in 65 out of 95 permanent plots. Only two species decreased in frequency in Skåne, but 14 species showed a decrease in Småland. All were typical grassland species and their decline may be regarded as a long-term response to ceased grazing and tree canopy closure as almost no tree cutting occurred during the study period in Småland. Total species richness increased with management intensity in Skåne. This was due to decreasing species losses and increasing establishment of new species at intense management. A small general increase in species numbers was recorded in Småland. Species richness was more closely related to soil pH in Skåne than in Småland. The floristic variability between the oak forest plots was closely related to soil pH in both Skåne and Småland. We suggest that changes of light conditions as a result of changes in forest management are important for current secondary succession in South Swedish oak forests, whereas the general floristic pattern is to a large extent controlled by soil acidity.     

Assessment and management of old-growth forests in south eastern Australia

Abstract

Old-growth forests in south eastern Australia are important for biodiversity conservation, recreation, carbon storage, social values and, to a declining extent, for timber production. Developing a comprehensive definition of old-growth forest that can apply across all Australian vegetation types has been challenging. Old growth can be viewed from ecological and social perspectives. For policy and management purposes old growth has been defined as a growth stage in forest development, incorporating ecological maturity and lack of evidence of past disturbance. Classification and assessment of old growth has largely been restricted to those areas covered by regional forest agreements (RFAs) between different states and the Federal Government. Old growth can be impacted by wildfire, timber harvesting, insect pests, diseases and other disturbances. Climate change will also present challenges for the future management of old-growth forests. There is increasing scientific understanding of the relationships between species, forest growth stage and old-growth forest attributes. To meet biodiversity conservation objectives, the management focus is shifting from assessing and protecting old-growth forests, to providing for forests across the landscape with old-growth attributes. This approach may be at odds with other conceptions of old growth based on notions of undisturbed systems free of human influence.     

Vegetation in Danish beech forests: the importance of soil,microclimate and management factors,evaluated by variation partitioning

The importance of management regime on floristic variation (mosses and vascular plants) in four Danish beech forests was investigated. Sixty-four blocks were sampled, representing beech stands of different age and management types. Nineteen potential explanatory variables were recorded and tested with Monte-Carlo tests and Canonical Correspondence Analysis. In addition results were evaluated by use of Detrended Correspondence Analysis. Explanatory variables were divided into three groups; soil, microclimatic and management parameters. The amount of variation explained by each group of variables was calculated by use of variation partitioning. The group consisting of management variables explained most variation, on local as well as regional scale. Management related variables explained more variation in vegetation than any other variables together. This indicates the importance of management as determining species composition in Danish beech forests. Management related variables explained most variation on local scale. On a regional scale, soil parameters explained the major part of the variation. The results suggest that thirty years without management are sufficient to change species composition significantly, as compared to managed forests.     

Immediate responses in soil chemistry,vegetation and ground beetles to soil perturbation when implemented as a restoration measure in decalcified sandy grassland

The species-rich calcareous grassland communities in Europe are gradually disappearing due to lack of management such as grazing or cultivation, resulting in decalcification and reduction of gaps in the vegetation. In this study, experimental soil perturbation (deep and shallow) was performed in degenerated sandy grassland in plots with a size of 8 × 8 m, using a randomised block design. The hypothesis that soil perturbation that inverts the soil layers decreases nutrient availability, creates vegetation gaps and thereby selects for desirable species was tested through comparisons with untreated controls as well as with nearby target habitats. The deep perturbation was designed to bring CaCO₃ up to the surface, whereas the shallow perturbation tested the effect of disturbance alone. The effects of soil perturbation on soil chemistry, vegetation and beetle communities were analysed for the 2 years following the treatments. Increased pH and calcium concentration, and decreased nitrogen and phosphorus availability, showed that deep perturbation was successful in restoring the soil chemistry to levels similar to those of the target habitat. Perturbated plots were rapidly colonised by the acid tolerant grass Corynephorus canescens, but the slow colonisation of the threatened calcicole species Koeleria glauca was an indication that the vegetation could be evolving towards the target vegetation. Six red-listed beetle species associated with open, dry grasslands were found, out of which four were found only in perturbated plots, although this could not be statistically tested. In conclusion, it may take many years or even decades for the establishment of desirable flora, and seeding could therefore be a suitable method of increasing the rate of succession.     

Long-term vegetation dynamics in the Šumava Mts. natural spruce-fir-beech forests

In 1972(74)–1996(98), repeated phytocoenological surveys of natural mixed forest remainders were made on permanent plots in the Šumava Mts. in the south-western part of the Czech Republic. The surveys were made in localities with subsoils poor in nutrients (Boubín-Milešice—27 plots) and in a locality with nutrient-rich subsoil (Stožec—15 plots). Vegetation dynamics were studied according to the year of measurement and the nutrient capacity of the geological bedrock. We used the indices of floristic similarity, the calculation of plant communities’ characteristics (Shannon–Wiener’s index, equitability index), the calculation of taxa characteristics (fidelity, average cover, constancy) and multivariate ordination analyses—indirect (DCA) and direct (CCA). Changes in environmental conditions were studied between the years of measurement and between the localities using bioindication—by the calculation of Ellenberg indicator values (EIV) for plant communities. Over 24 years both the nutrient-poor site and the nutrient-rich site showed a considerable reduction in the tree layer cover and conversely the advancement of shrub layers. The coverage degree of dominants in the main tree layer (Fagus sylvatica, Picea abies and Abies alba) markedly decreased. Abies alba also exhibited a pronounced drop in constancy. On the other hand, the lower tree layer and shrub layers in Boubín-Milešice exhibited a distinctive invasion of Fagus sylvatica. An increase in the frequency of Sorbus aucuparia and a decrease in the frequency of Ulmus glabra were determined too. Herb layer changes were highly significant between the 1970s and the 1990s with qualitative changes being greater than quantitative changes. The number of species and Shannon–Wiener’s index increased. A significant difference was recorded between the nutrient-poor and the nutrient-rich sites in the values of the quantitative similarity of relevés with other differences being insignificant. The nutrient-poor sites exhibited herb layer homogenisation. A significant increase of EIV for light was found on both site types. The changes in phytocoenoses were interpreted partly as developmental trends (caused by indirect impact of man—e.g. fluctuations in game populations since the 18th century, the impact of air pollution); partly as cyclical changes connected with the developmental cycle of the natural temperate forest.     

Disturbance of suburban Fagus forests by recreational activities: Effects on soil characteristics,above‐ground vegetation and seed bank

Questions: How does recreational disturbance (human trampling) affect soil characteristics, the performance of the understorey vegetation, and the density and species composition of the soil seed bank in Fagus sylvatica forests? Location: Suburban forests near Basel, northwestern Switzerland. Methods: We compared various soil characteristics and the performance of the understorey vegetation in six beech forest areas frequently disturbed by recreational activities with those in six undisturbed control areas, in spring 2003. In the same forest areas, the soil seed bank was investigated using the seedling emergence method. Samples were obtained from soil cores in January 2003. Results: We found substantial changes in soil compaction, above‐ground vegetation and in the soil seed bank due to recreational activities. In frequently visited areas, soil compaction was enhanced which caused a decrease in cover, height and species richness of both herb and shrub layers. Compared with control areas, the number of trampling‐tolerant species of the seed bank was significantly higher in disturbed areas, and total species richness tended to be higher in disturbed than in control areas. Furthermore, the similarity in species composition between the above‐ground vegetation and seed bank was significant lower in disturbed than in control areas. Conclusions: The intensive use of suburban forests for recreational activities, mainly picnicking, affects the vegetation of natural beech forests. Our study indicates that a restoration of degraded forest areas from the soil seed bank would result in a substantial change of the vegetation composition.     

Relationships between the vegetation and soil conditions in beech and beech-oak forests of northern Germany

In this study we examine the relationships between the vegetation of beech and beech-oak forest communities (Hordelymo-Fagetum, Galio-Fagetum, Deschampsio-Fagetum, Betulo-Quercetum) and their soil conditions in the lowlands of northern Germany, based on 84 sample plots. In all plots the vegetation was recorded and soil parameters were analysed (thickness of the O- and the A-horizons, pH, S-value, base saturation, C/N, mean Ellenberg moisture indicator value). The vegetation classification according to the traditional Braun-Blanquet approach was compared with the result of a multivariate cluster analysis. Vegetation-site relationships were analysed by means of an indirect gradient analysis (DCA).Both traditional classification methods and the cluster analysis have produced comparable classification results. So far as the species composition is concerned, a similar grouping of sample plots was found in both approaches. Multivariate cluster analysis thus supports the classification found by the Braun-Blanquet method. The result of the DCA shows that the four forest communities mentioned above represent clearly definable ecological units. The main site factor influencing changes in the species composition is a base gradient, which is best expressed by the S-value. In addition, within the series Hordelymo-Fagetum - Galio-Fagetum - Deschampsio-Fagetum the C/N-ratios and the thickness of the organic layers (O-horizon) increase continuously. By contrast, the floristic differences between oligotrophic forest communities (i.e., Deschampsio-Fagetum and Betulo-Quercetum) cannot be explained by a base gradient and increasing C/N-ratios. It is suggested that a different forest management history in some cases (e.g., promotion of Quercus robur by silvicultural treatments) is responsible for differences in the species composition, but on the other hand the result of the DCA indicates that Fagus sylvatica is replaced by Quercus robur with increasing soil moisture (i.e., with the increasing influence of a high groundwater table). Summarizing these results, it can be concluded that the ecological importance of single site factors affecting the species composition changes within the entire site spectrum covered by the beech and beech-oak forests of northern Germany.     

Prediction of macrofungal occurrence in Swedish beech forests from soil and litter variable models

The spatial distribution of 49 macrofungal species in Swedish beech forests was related to the statistical variation in 31 edaphic variables. In order to reduce the multicollinearity problem, the variables were transformed into eight principal components, PCs, which are used in two-group discriminant analysis (on absence/presence patterns) and multiple regression analysis (on number of fruit-bodies). The results suggested that base saturation and organic matter content are of outstanding importance. However, significant relationships were also found with other variables, i.e. Cd or Zn in soil and litter, soil nitrogen mineralization rate, and Na or S in litter. One interesting interpretation of the results is that fungi do not only respond to the main variables of a gradient (soil pH, organic mater, base saturation) but also to other variables. Attempts were made to interpret the PCs to characterize fungal occurrence from the models they formed.     

Nutrient pools and fluxes of the ground vegetation in coniferous forests due to fertilizing,liming and amelioration

The effects of fertilization and amelioration treatments on some nutrient pools and fluxes of ground vegetation in mature pine and spruce stands on acid soils in South Germany are described. In N-limited pine forests with moderate canopy density and with Deschampsia flexuosa an additional N-accumulation in biomass of 20–40 kg ha^-1 occurred 3 years after pure N-fertilization. The N, P, K-cycling through ground vegetation was stimulated more than 10 years by a combined N + CaCO₃ + P treatment leading toa shift in dominance from cryptogams and Ericaceae towards Deschampsia flexuosa and ruderal species like Epilobium angustifolium. The effect of a lupine treatment (combined with initial soil preparation, liming and P supply) was far stronger than the effect of the other experimental procedures. But the fertilizer and amelioration effects on the herb layer of pine forests tended to decline after two decades for different reasons.The shade-tolerant ground vegetation in a nitrogen-saturated spruce forest was not able to prevent heavy additional nitrate losses from upper mineral soil after dolomitic liming. But the Ca, Mg and K fluxes through ground vegetation were strongly elevated in the third year after treatment.     

Sixty years of vegetation dynamics in a south boreal coniferous forest in southern Norway

Abstract. Vegetation data from permanent plots were collected in 1931, 1961 and 1991 in a south boreal forest 20 km north of Oslo in southern Norway. Major changes were found in the vegetation composition during those 60 years. The main changes were a reduction in the frequency of species and the frequency of joint occurrences of vascular species such as Andromeda polifolia, Calluna vulgaris, Cornus suecica, Eriophorum vaginatum, Maianthemum bifolium, Melampyrum pratense, Trientalis europaea, Vaccinium uliginosum and V. oxycoccus, and mosses, e.g. Dicranum fuscescens, Hylocomium splendens, Pleurozium schreberi, Ptilidium ciliare and Ptilium crista-castrensis. The observed changes were interpreted as being induced by internal processes e.g. notably a long-term change from paludified forest to mesic forest. In particular the growth of Picea abies seems to be a main driving force. The dominance of Picea abies and Vaccinium myrtillus appears to have rendered the conditions more unfavourable for other species. A doubling of the living stem biomass of P. abies during the last 67 yr shows that this old-growth forest has not yet reached a steady state. It was demonstrated that species such as Deschampsia flexuosa and Molinia caerulea did not increase in frequency in response to nitrogen deposition, as has occurred elsewhere in northern Europe. pH in the humus layer increased with 0.2 unit from 1961 to 1991. The results of this study indicate that protection from logging has initiated the reduction of species in the field layer and bottom layer. This study questions if monitoring of forest vegetation should be restricted to protected forests as is the practice in Scandinavia today. We recommend that also areas with some kind of selective cutting will be used for monitoring of forest vegetation.     

Deer herbivory as an important driver of divergence of ground vegetation communities in temperate forests

Ungulate herbivory can fundamentally affect terrestrial vegetation at the landscape and regional levels, but its impact has never been analyzed from meta‐community perspectives. Here, we study a meta‐community of forest ground‐layer plants in a warm‐temperate region along a clear gradient of deer density interplaying with gradients of other environmental factors (forest type, sky openness and topographic wetness). Canonical corresponding analysis showed that deer density was the most important determinant of species distributions. These distributions conformed to a two‐directional filtering model, which selects for competitive species at low deer density but favours herbivory‐tolerant plants at high deer density, with these two directions counterbalancing each other when herbivory is intermediary. This resulted in a bi‐directionally nested meta‐community, in which local species richness was highest at intermediate levels of deer density, conforming also to the intermediate disturbance hypothesis. Our results suggest that herbivory can be the most important driver of meta‐community structure in mesic systems; this contrasts with the results of earlier studies conducted in harsh environments, where species sorting by abiotic factors at early life stages reduced the role of biotic interactions, including herbivory.