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1.
In Norway black alder (Alnus glutinosa) has an 'optimal' area along the western coast where it acts as a pioneer species in secondary successions on Calluna and grass heaths, pastures, formerly cultivated land and in hydroseres. Black alder is dominant or co–dominant with birch in oligotrophic grazing forests, most of which belong to the ass. Corno suecicae–Betuletum where black alder seems to be able to survive for a long time. It is also found in a variety of other woodland communities, some of which are stable Alnetea glutinosae or Alno–Padion communities. Others are successional stages towards meso– or eutrophic deciduous forests. The new Alnetea glutinosae ass. Carici nigrae–Alnetum glutinosae is described. The ecology of black alder in West Norway is compared to its ecology in other areas, especially on the British Isles. The humid climate and recent changes in agricultural practice are the main reasons for the present abundance of black alder in West Norway.  相似文献   

2.
Abstract This study reports on the foraging profile of a wandoo woodland avifauna at Dryandra in Western Australia, Australia. Despite its geographical isolation, wandoo woodland shares a large number of species with woodland bird communities in eastern Australia and there are broad similarities in community foraging profiles. Insect-eating birds using ground, bark, foliage, and aerial substrates dominate eucalypt bird communities. Nectar-feeding and seed/fruit-eating guilds are important components of the Australian avifauna, but have fewer species, and vary in composition and abundance as nectar, seed, and fruit availability changes seasonally and from year to year, and from one locality to another. Despite similarities, there are also differences between the foraging profile of the wandoo avifauna and those in eastern Australia. Specifically, the wandoo avifauna is characterized by a high proportion of ground-foraging species. In addition, many wandoo woodland birds appear to spread their foraging over a wider range of substrates (i.e., ground, bark, and foliage) than eastern species. Differences in habitat structure do not explain these differences in community foraging profiles, and there may be differences in the abundance, kind, and spatial distribution of resources between different eucalypt ecosystems. Possibly the eastern communities have lost ground-dwelling components of their avifauna since European settlement, while the woodlands at Dryandra retain a more intact avifauna. The reasons why some species and not others are lost from woodlands as a result of European land management practices are discussed.  相似文献   

3.
The Farm Woodland Scheme, which provided incentives to convert agricultural land to timber production, contained an implicit assumption that farm woodlands produce important benefits for wildlife. The moth fauna of 18 farm woodlands in the Vale of York was surveyed between May and November 1991. The aims were twofold. The first was to determine if there were benefits for moth species diversity. The second was to ascertain whether concepts of island biogeography and the plant species richness of the woods were related to the moth species composition.Eleven families, 214 species and over 16 000 individuals of moths were recorded. Classification of the species presence/absence matrix indicated that small woods (less than 1ha) did not have characteristic woodland moth communities. Woods larger than 5ha were judged to be more valuable for the long-term conservation of woodland moth diversity. The best predictor of moth species richness was the herbaceous plant species richness within woodlands. Species richness of the family Geometridae was positively related to woodland area, as well as to woodland shape (compact shapes being preferable to elongated shapes). Characteristic woodland species are influenced by isolation (less isolated woods being richer in species). The implications of different powers of dispersal between moth families are discussed. Farm woodlands will be of more value for the conservation of the Macrolepidoptera if they are large, compact and incorporate remnants of existing woodland with extant herbaceous vegetation. These should be factors which are taken into consideration when providing incentives to establish and manage farm woodlands.  相似文献   

4.
《Bird Study》2012,59(3):293-305
ABSTRACT

Capsule: Smaller woodlands not only support fewer species but also show different avian community composition due to loss of woodland interior and an increase in edge habitat.

Aims: To use observed community composition changes, rather than traditional total species richness-area relationships, to make area-specific management recommendations for optimizing woodland habitat for avian communities in fragmented landscapes.

Methods: 17 woodlands were selected in Oxfordshire, UK, with areas between 0.2 and 120 ha. Three dawn area searches were conducted in each woodland between 1st April and 28th May 2016 to record encounter rates for each species. The impact of internal habitat variation on woodland comparability was assessed using habitat surveys.

Results: Woodlands with area less than 3.6 ha showed a significant positive relationship between total avian species richness and woodland area. Woodlands with area over 3.6 ha were all consistent with a mean (± se) total richness of 25.4?±?0.6 species, however the number of woodland specialists continued to increase with woodland area. Woodland generalists dominated the total encounter rate across the area range, however the fractional contribution of woodland specialists showed a significant positive correlation with woodland area, while the fractional contribution of non-woodland species significantly decreased. Non-woodland species numbers peaked in mid-sized woodlands with enhanced habitat heterogeneity.

Conclusions: Community composition analysis enabled more targeted recommendations than total species richness analysis, specifically: large woodlands (over 25?ha) in southern UK should focus conservation efforts on providing the specific internal habitats required by woodland specialists; medium-sized woodlands (between approximately 4 and 25?ha) should focus on promoting internal habitat variety, which can benefit both woodland species and non-woodland species of conservation concern in the surrounding landscape; small woodlands (under 4?ha) should focus on providing nesting opportunities for non-woodland species and on improving connectivity to maximize habitat for woodland generalists and facilitate movement of woodland specialists.  相似文献   

5.
This paper appraises the role of prehistoric human societies in modifying the natural woodland biodiversity of several regions throughout Scotland. It draws attention to the likelihood that, contrary to popular belief, biodiversity was enhanced by interactions between agricultural communities and woodlands. The possible purposefulness of such interactions is discussed. Mindful of the present concern to re-establish ‘native’ woodlands in many parts of northern Britain, we then review three approaches to the identification of native tree types in Scotland, and conclude that insufficient attention in reafforestation schemes is being paid to (a) the palaeoecological record as a record of native woodland or (b) the likely former high taxonomic diversity of woodlands. Both these failings will lead to the creation of new woodlands lacking in species diversity.  相似文献   

6.
Fire‐maintained woodlands and savannas are important ecosystems for vertebrates in many regions of the world. These ecosystems are being restored by forest managers, but little information exists on herpetofaunal responses to this restoration in areas dominated by shortleaf pine (Pinus echinata). We compared habitat characteristics and herpetofaunal communities in restored pine woodlands to relatively unmanaged, second‐growth forests in the Ouachita Mountains of western Arkansas, USA. We found woodland restoration with periodic burning affected species differently; some species benefited, some species appeared negatively affected, but most species did not respond clearly either way. Overall reptile captures were significantly (p = 0.041) greater in pine‐woodlands than in unrestored forest; one species of snake and three species of lizards were captured more often in woodlands than unrestored forests. Among anurans, we found no significant difference in captures between woodlands and unrestored forests for any species. Among salamanders, we captured western slimy salamanders (Plethodon albagula) almost exclusively in unrestored forest, but captures of other species did not differ between the two treatments. Historically, the Ouachita region likely consisted of a mosaic that included both fire‐maintained habitats (woodlands, savannas, and prairies) and areas of denser forest on mesic sites that were less likely to burn. Consequently, landscapes that retain both open woodlands and denser, less‐intensely burned forest (in the form of unharvested greenbelts or separate stands) would likely promote and maintain a greater diversity of herpetofauna.  相似文献   

7.
The Convention on Biological Diversity’s Aichi Target 15 requires global restoration of degraded ecosystems including complex examples. A case is made for the deliberate creation of woodlands with ancient characteristics. In the temperate biome, efforts to restore such communities will be accelerated by intervention facilitating natural succession. Negative rhetoric regarding the irreplaceability of ancient communities may hinder such considerations. Some facets of ancient woods are irreplaceable and their destruction is discouraged. Nevertheless, as human population and impact increase, this resource will degrade. Though understanding of many ecological processes is incomplete, ecological restoration requires proactivity. Physicians need not fully understand the healing process to rely upon it and, fortunately, ecology carries similar intangible reliables; natural succession occurs and complex communities actively self-assemble. Accepting this, then woodland with many characteristics of ancientness can be deliberately created. Thermodynamic principles may assist and seeking to initiate a biodiversity cascade is proposed as a pragmatic approach. The intricacy that defines ancient woodland might thus be assembled in timescales of less than a century. Ascension Island’s anthropogenic cloud forest provides a precedent. For utilitarian purposes, human-mediated plant dispersal (deliveries of plants to the island), led to the transformation of species-poor, fern-dominated hillsides to species–rich cloud forest in about 100 years. How much more could be achieved with appropriate ecological intention?  相似文献   

8.
During the past 150 years forest management has dramatically altered in Central European woodlands, with severe consequences for biodiversity. Light forests that fulfilled variable human demands were replaced by dark high forests that function solely as wood plantations. In the Alps, by contrast, open woodlands are still present because the traditional land use as wood pasture has remained and physiographical conditions favour natural dynamics. The aim of our study was to investigate the effects of succession on the Orthoptera communities of alluvial pine woodlands in the northern Alps. Orthoptera showed a clear response to succession, with each successional stage harbouring a unique assemblage. The influence of succession on species richness and abundance were identical: The values were highest in the intermediate and lowest in the late seral stage. The diversity and abundance peak in the mid-successional stage probably reflects a trade-off between favourable ambient temperatures for optimal development and sufficient food, oviposition sites and shelter against predators. Food shortage and easy access for predators seemed to be limiting factors in the early successional stage. In contrast, in the late successional stage adverse microclimatic conditions probably limit Orthoptera occurrence. Although all three successional stages of the pine woodlands are relevant for conservation, the early and mid-successional stages are the most important ones. Conservation management for Orthoptera in this woodland type should aim at the reintroduction of cattle grazing and the restoration of the natural discharge and bedload-transport regimes of the alpine rivers.  相似文献   

9.
Abstract. The cessation of coppicing and grazing in Quercus woodlands, with its subsequent changes in the structure, composition and functioning of vegetation communities, is becoming more frequent throughout the Mediterranean Basin. In southern France, we have studied successional changes in Quercus pubescens woodlands by visiting previously studied sites 18 yr later. Changes in vertical structure, species richness, floristic composition, life form and dispersal type were analysed and compared between woodlands that had previously been grazed or ungrazed. Both successions showed a decline in vegetation cover in the 0–25 cm height class and in the height class immediately under the canopy layer, due to oak litter accumulation and tree ageing. In post‐grazing succession, the abandonment of grazing and associated burning has allowed the vegetation cover to increase in the 0.25‐2 m height class. In both successions, grassland species decreased in frequency and forest species increased, a trend which was stronger in undisturbed succession. Species richness decreased with time in the undisturbed succession, but remained stable in the post‐grazing succession mainly because of the slow decline of plants linked to grazing. In undisturbed succession, therophytes and hemicryptophytes decreased. In contrast, therophytes and hemicryptophytes remained stable in post‐grazing succession. In both successions, endozoochorous species (notably Ruscus aculeatus) increased. Plants dispersed by non‐animal vectors decreased in undisturbed succession, but stability was observed in most of the dispersal types in post‐grazing succession. These results showed that a time‐lag existed between undisturbed succession and post‐grazing succession, the latter remaining at a younger stage of successional development due to more recent impact of grazing. However, both successions have converged suggesting that most of the traces of grazing on vegetation will disappear within a few years. The vegetation of these coppices, regardless of the previous grazing regime, will become increasingly similar to the vegetation of undisturbed woodlands. However, their floristic composition will probably never be identical to that of undisturbed woodlands, mainly because of the rarity of these undisturbed woodlands and of the short‐distance dispersal of many forest plant species.  相似文献   

10.
Abstract. 315 isolated semi-natural and natural stands in NW Germany were investigated floristically, 285 stands of ancient woodlands and 30 recent ones. In the study area nearly all semi-natural and natural ancient woodlands are found on mesotrophic or eutrophic sites and can be assigned to the Fagetalia. 54 selected herbaceous and five woody Fagetalia-species have been tested in their association to ancient woodlands. 21 of the 59 selected plant species show a highly significant association to ancient woodlands and seven species show a weak significance. 31 plant species are not significantly correlated with ancient woodland sites, but 25 of them have a low frequency. The result shows that investigations of the historical ecology can help to understand floristic composition of present-day woodlands. Restriction of many woodland species to ancient woodlands, especially rare species, emphasizes the importance of woodlands with a long continuous history for the preservation of endangered species. Irrespective of ecological conditions, the restriction of plant species to ancient woodlands seems to be mainly caused by their low ability to colonize recent woodlands, especially isolated stands. Differences in the association to ancient woodlands between European countries are assumed to be a function of both time and degree of isolation of woodlands, of the dispersal mode of the plant species and of the availability of suitable habitats.  相似文献   

11.
In north-west Germany the ground beetle fauna was investigated using pitfall traps at 79 sampling sites in ancient woodlands and recent woodlands (with and without direct contact to old stands). Two woodland types were considered: The Quercion robori-petraea-woodlands (oak-beech-type) on mainly sandy soils and the Stellario-Carpinetum-woodlands (hornbeam-type) on mainly loamy soils. The number of recorded ground beetle species inhabiting exclusively or predominantly woodlands in the investigation area is significantly higher in ancient stands of both woodland types than in recent ones. No statistically substantiated relation between habitat size (both about 1800 and in 1990) and the number of characteristic woodland ground beetle species could be ascertained. Carabus glabratus and Abax parallelus show a distinct focus in ancient woodlands. Significantly more records of Carabus violaceus and Abax parallelepipedus are known from ancient woodlands than from recent ones. Twelve of the 16 ground beetle species, for which no difference in the colonisation of ancient and recent woodlands was ascertained, are macropterous. Half of the eight brachypterous woodland species is exclusively or predominantly found in ancient woodlands, suggesting that power of dispersal is an important factor which determines the species number in woodland fragments of different age.  相似文献   

12.
Aim Lowland woodlands in Europe went through dramatic changes in management in the past century. This article investigates the influence of two key factors, abandonment of coppicing and increased pressure of ungulates, in thermophilous oakwoods. We focused on three interconnected topics: (1) Has the assumed successional trend lead to impoverishment of the vegetation assemblages? (2) Has it resulted in vegetation homogenization? (3) Are the thermophilous oakwoods loosing their original character? Location Czech Republic, Central Europe. Methods The vegetation in 46 semi‐permanent plots was recorded three times: firstly, shortly after the abandonment of coppicing (1953) and then, after four to six decades of secondary succession and strong game impact (1992 and 2006). Overall trends and changes in species spectra were analysed. Results There is a marked successional shift towards species‐poorer communities growing in cooler, moister and nutrient‐richer conditions. The change was significantly different in parts affected and unaffected by high numbers of ungulates yet only for herbs, not the woody species. However, observed change in species composition was not accompanied by significant homogenization process that is the general process reported from elsewhere. A sharp decline in plant species typical for thermophilous woodland communities and in endangered species indicates that the original character of the woodland has been gradually lost. Main conclusions Thermophilous oakwoods have been largely replaced by mesic forests. Lowland oakwoods in continental parts of Europe historically depended on active management, which kept the understorey conditions light and warm. Successional processes in the 20th century caused a critical loss of species diversity at various spatial levels. However, artificially high numbers of ungulates, which otherwise have a negative impact, probably held up succession, so that the changes may still be reversible.  相似文献   

13.
Taxonomic homogenization (TH) is the increasing similarity of the species composition of ecological communities over time. Such homogenization represents a form of biodiversity loss and can result from local species turnover. Evidence for TH is limited, reflecting a lack of suitable historical datasets, and previous analyses have generated contrasting conclusions. We present an analysis of woodland patches across a southern English county (Dorset) in which we quantified 70 years of change in the composition of vascular plant communities. We tested the hypotheses that over this time patches decreased in species richness, homogenized, or shifted towards novel communities. Although mean species richness at the patch scale did not change, we found increased similarity in species composition among woodlands over time. We concluded that the woodlands have undergone TH without experiencing declines in local diversity or shifts towards novel communities. Analysis of species characteristics suggested that these changes were not driven by non-native species invasions or climate change, but instead reflected reorganization of the native plant communities in response to eutrophication and increasingly shaded conditions. These analyses provide, to our knowledge, the first direct evidence of TH in the UK and highlight the potential importance of this phenomenon as a contributor to biodiversity loss.  相似文献   

14.
Saproxylic beetle diversity is high at the Cabañeros National Park (central Spain), where woodland habitats exhibit remarkable heterogeneity. Our aim was to explain the diversity of saproxylic beetles, focusing on species turnover among mature woodland types. We surveyed five woodland types that represented the heterogeneity of the park’s woodland habitats. Beetles were collected using window traps over a period of 20 months. The Jaccard Similarity Index was used as indirect value of beta diversity among woodlands and to test the relation between species turnover and geographical distance. We also identified the contribution of species turnover to landscape diversity by using a partitioning model. Moreover, the presence of mixed woodlands (more than one tree species) allowed us to attempt to valorise the effect of tree species (coupled with their historical management) on species turnover among woodlands. Finally, we looked for different saproxylic beetle preferences for habitat and tree species using an indicator value method. We found that saproxylic beetle species composition varied significantly among the studied woodlands. The variation in species turnover was independent from the distance among woodlands, which suggested that beetle dispersal abilities could not explain this high turnover. Tree species within woodlands were a key factor that increased diversity turnover in woodlands and, consequently, the diversity of the park. Moreover, we found saproxylic beetle species that had different habitat and tree species preferences. We conclude that woodland heterogeneity (highly affected by woodland composition) seems to be the driving force for saproxylic beetle diversity in this protected area.  相似文献   

15.
Abstract. On the Vecht river plain (western Netherlands), small fens, remnants of a large mesotrophic wetland bordering a moraine, of 1 to 5 ha are found in a man-made matrix of lakes and pastures. The regional position of the fens, local position of sampling sites, composition of the vegetation and local hydrological variables were measured. Polders in the river plain produce a complex hydrology obscuring the regional zonation between moraine and river. Water supply and species composition are determined more by a site's regional than local position. High-productivity reedlands are abundant close to the river. Carex paniculata reedlands receive large amounts of river water, which gives their fen water a high K+ concentration. Low-productivity C. diandra fens and litter fens have their optimum closer to the moraine. C. diandra fens are fed mainly by inflowing nutrient-poor ground- or surface water; litter fens receive primarily rainwater. Nutrients in fen water and in peat are lowest in C. diandra and C. lasiocarpa fens, but do not differ significantly between the communities. In both, iron seems to be more important than calcium in reducing phosphate solubility. Iron richness in the C. diandra fens is caused by present inflows of ground- or surface water, while in C. lasiocarpa fens, which succeed the former, iron richness is the result of historical inflows.  相似文献   

16.
Biodiversity patterns of the woodland-steppe ecotone in southeastern Inner Mongolia were investigated. Controlled by climatic factors, the plant species diversity of the woodland-steppe ecotone is moderate as compared with the adjacent woodland and steppe communities. From woodland through woodland-grassland and woodland-steppe to steppe, about 2/3 species were replaced at each boundary; only seven herb species were detected to be distributed in all four vegetation zones. Landscape classification based on landform, climate, and vegetation shows that landform condition is most critical to landscape diversity in the studied area. The most fragmented landform in the woodland zone does not necessarily lead to low plant species diversity. However, similar understory species in different woodland types lead to continuous woodland vegetation and, hence, high species richness. High fragmentation in the woodland-steppe zone and discontinuous distribution of woodlands might be a driving factor for lower species richness. Reconstruction of the Holocene climatic changes and vegetation development demonstrates that the highest plant species diversity occurred in the ecotone from 4500 to 2500 14C yr BP at different sites, while the woodland zone extended much farther northwestward. When woodlands retreated from the current ecotone with climatic drying, the fragmentation of woodlands in the current ecotone led to plant species loss.  相似文献   

17.
Abstract. The vegetation of the SkoHzanka Reserve, situated on a limestone hill near Krakow, was examined over a 30 year period, using the Braun-Blanquet method. With the help of a numerical classification eight types of grassland communities were distinguished, belonging to the classes Sedo-Scleranthetea, Nardo-Callunetea and Festuco-Brometea, and 11 types of woodland communities, both remnants of ancient woodlands from the classes Querco-Fagetea and Vaccinio-Piceetea and more recent woods. In the case of grasslands the results of detrended correspondence analysis (DCA) indicated that the largest variation was associated with the soil type. Woods on sandy soils are very different from those on calcareous soils, and the younger recent woods are very different from the ancient woodlands. An analysis of historical cartographic material and aerial photographs shows that in the last few decades the area of recent woods has increased considerably at the expense of grasslands. Changes in species diversity in the woods during secondary succession and their successional convergence were examined and discussed. It was found that young and mature woods on sandy soils are more similar to each other than young and mature woods on calcareous soils. These differences are mainly related to the fact that many woodland herb species growing in rich, broadleaved ancient woods are unable to colonize recent woods since they have a limited colonization capacity.  相似文献   

18.
Abstract. Recent studies indicate that, in the present-day agricultural landscape, the floristic composition of young woodland communities can be fully developed if the woods are situated adjacent to ancient woodlands. Four 70-yr-old deciduous woods in the Carpathian foothills were examined in relation to three adjacent ancient oak-hornbeam and oak-pine woodlands, which are the nearest source of woodland species diaspores. On the basis of data from 208 plots, the frequencies of various species groups in the field layer of the woods were analysed. The dependence of vegetation differentiation within the recent woods on (a) distance to the border with the ancient woodlands and (b) light intensity was examined by Partial Detrended Canonical Correspondence Analysis (DCCA). A significant relation between distance to ancient woodland and species composition was found for recent woods on rich brown soils. The vegetatively propagating species, myrmecochores and small autochores attained higher cover values near ancient woodland; endozoochores and anemochores were most abundant further away. Within recent, more open woods on poor podzolic and leached brown soils, colonisation is strongly inhibited by dense growth of Carex brizoides; here, vegetation regeneration is much slower than in woods on rich soils much further away from the source of diaspores.  相似文献   

19.
Habitat creation and management within wooded networks is a potentially effective strategy to reduce ecological isolation and the deleterious effects of fragmentation. However, questions remain over the relative advantages of different approaches, e.g. buffering patches vs. increasing connectivity. Potential effects of woodland fragmentation include reduction in regional woodland cover, reduced patch size, edge effects with loss of core habitat, and increased isolation with disruption of dispersal and metapopulation dynamics. We adopt an evidence-based approach to review how each of these affects woodland birds with an emphasis on studies from the UK and use this to identify management priorities for mitigation. There is evidence for both patch area and composition effects: larger woodlands support more woodland bird species, and woods located within sparsely wooded landscapes are less valuable to specialist woodland species. Bird assemblages show a nested pattern with respect to area, and thus species found in small woods also occur in large woods but not vice versa. However, small woods may be preferred by a few edge species, while small woods also have greater variability in bird species composition. Consideration of the metapopulation dynamics of specialist species with poor dispersal shows that creating or buffering large woodlands is more efficient than a greater total area of small fragments. Connectivity appears most useful for widespread generalist species with almost continuous populations. Woodland structure and quality are of overwhelming importance: as well as mature woodland, young growth, scrub and edges are also key components. There is an urgent need to examine the relationship between nest predation and landscape structure within UK woodlands.  相似文献   

20.
Multi-species indicators are often used to assess biodiversity trends. By combining population trends across several species they summarise trends across a community. Composite indicators such as these are useful for examining general temporal patterns and may suggest important drivers of biodiversity change. However, they may also mask substantial spatial variation in population trends, particularly when they are calculated over large spatial regions. We produced spatially-explicit indicators for farmland and woodland bird communities in the UK and further separate these into trends for generalist and specialist species within each group. We found considerable spatial variation in the indicators, which is masked by indicators calculated at the national level. The farmland community indicator showed mostly positive trends in western areas and extensive declines in south-east England. The woodland community indicator showed a north–south divide, with increases in Scotland and northern England and stability in the southern regions. For both communities, indicator trends for specialist species were more negative than those for generalists. We found no significant difference in farmland community indicators between arable land and improved grassland. Woodland specialists had significantly more negative trends in broadleaf compared to coniferous woodlands, suggesting habitat-type is one of the drivers of changes in the woodland community. These spatial patterns in bird population trends may be used to highlight regional conservation priorities and identify where those may differ from the national scale. In combination with information about other environmental changes, they may also be used to develop hypotheses about potential drivers of change. We advocate that this approach is adopted for other taxa and geographical areas.  相似文献   

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