Woodland Characteristics Research Articles

Influence of canopy structural complexity on urban woodland butterfly species richness

AbstractAs urban land use expands, understanding the conservation of biodiversity in urban settings becomes increasingly important. Urban areas contain a wide range of remnant natural, semi-natural and anthropogenic woodlands but the biodiversity of these woodlands is not well studied. Urban woodlands are usually constrained in size and subject to management which may not be focused on promoting biodiversity. As a habitat of critical importance, the characteristics of urban woodlands need to be better understood to maximise their biodiversity within a limited footprint in the urban landscape. We used repeat line-transect surveys and rapid woodland structure habitat assessments to investigate the habitat associations of butterflies in ten woodland patches representing a range of sizes (between 1 and 40 ha), ages and woodland characteristics in the urban habitat matrix of Milton Keynes, UK. We found that ancient woodland sites supported every species detected, but the butterfly communities of amenity and roadside woodlands had similar species richness, diversity and abundance, regardless of size. Butterfly species richness was strongly associated with both woodland area and structural complexity at a site-scale, but only with structural complexity on a transect scale. Simpson diversity showed no correlation with any variable at the site scale, but strong correlation with structural complexity on transects. Abundance only correlated with area at the site scale. Our results suggest that management techniques that introduce structural complexity within urban woodlands may be an effective way to support butterfly richness and diversity in contexts where woodland areas cannot be increased.

Biomass difference between mixed plantations and monocultures and its influencing factors: A meta‐analysis

AbstractEstablishing mixed‐species plantations has become the most promising planting method to provide various goods and improve multiple environmental services. Although mixed planting has the potential to increase tree biomass, the divergent findings make it challenging to understand the mixing effects on whole forest (trees, shrubs, herbs, and litter) biomass. Therefore, we conducted a meta‐analysis compiling 156 studies published from 1982 to 2021 across 128 sites in China. We aimed to quantify the mixing effects on forest biomass between mixed plantations and monocultures and disentangle the driving factors. Our results showed that mixed planting significantly increased the total biomass, biomass of tree, and shrub layer by 14.07%, 22.49%, and 34.84%, respectively, when compared with monocultures. The effects of mixed planting on biomass were more pronounced in plantations with both nitrogen‐fixing trees and non‐nitrogen‐fixing trees, plantations with both coniferous and broad‐leaved trees, as well as uneven‐aged plantations containing young‐ and middle‐aged species. Furthermore, our results demonstrated the effects of mixed planting were predominantly governed by climatic conditions and woodland characteristics. The effect size of total biomass exhibited a significant positive correlation with mean annual temperature and precipitation, while the shrub and herb layers showed a significant negative relationship with these climatic variables. Our findings highlighted the importance of complementarity effects in mixed plantations, especially establishing uneven‐aged plantations with different leaf morphology types and N acquisition strategies. Overall, our meta‐analysis could provide strategies for future sustainable ecosystem management and improving the terrestrial carbon sink.

Variability in the Hydrological Processes of Six Typical Woodlands Based on Stable Isotopes in Subtropical Regions in Central China

Changes in woodland characteristics induced by plants and soil greatly affect soil hydrological processes. Stable isotope technology and indoor soil moisture characteristic experiments were conducted at three rainfall levels (3.6, 23.5, and 49.8 mm) to investigate the hydrological processes under six woodlands (two pure forests and four mixed forests). The main influencing factors contributing to these changes were identified in a low mountain and hilly region in central China. The soil waterline equation in this area was soil water δD = 5.626 δ18O − 16.791 (R2 = 0.798). The slope and intercept in the soil waterline equation were smaller than the atmospheric waterline equation. From a temporal perspective, the soil moisture content varied in the same trend under different rainfall events, with the maximum and minimum values on the first day after rainfall and the day before rainfall, respectively. However, an overall trend that first increased and then decreased was observed. From a spatial perspective, the soil moisture content increased with soil depth, and the increase rate was in the order of 0–20 cm and 20–40 cm in different soil layers. The soil moisture content in mixed conifer broadleaved woodlands was high. The soil water δD and δ18O in mixed conifer broadleaved woodlands and underground soil were relatively depleted. The effects of soil water-holding capacity, particle size composition, slope, canopy closure, and other factors on soil hydraulic parameters were comprehensively analyzed. The results showed that the extremely coarse sand (1–2 mm) particle content was the main parameter affecting soil-saturated hydraulic conductivity Ks, whereas the slope was the main factor affecting soil water δD and δ18O. In needle-leaved forests, the soil water infiltration form was a rainwater and soil water mixture downward diffusion, whereas the rainwater replaced the original soil water in the needle and mixed conifer broadleaved forests.

A method for rapid assessment of bat richness using woodland structure characteristics

1.To conserve and restore forests we need greater and more efficient assessment of their biodiversity. Integrating species monitoring into woodland inventories provides opportunities to develop more targeted and sustainable management plans; however, such monitoring often requires specialist knowledge of species and survey techniques and can be prohibitively costly to undertake. Where such surveys are not a legal requirement, proxy-based biodiversity assessments can provide a rapid and cost-effective method for estimating species assemblages. We propose a method to assess the value of temperate woodland for bats based on measures of woodland structural characteristics that can be readily obtained during routine woodland inventories.2.We sampled seven woodland characteristics together with bat richness (number of species) in 52 native broadleaved woodlands in England and Wales. We used generalized additive modelling to find the most parsimonious model that also explained the largest amount of variance in bat species richness.3.The best model included the amount of understory vegetation (clutter) and number of stems per hectare. These woodland characteristics are informative for predicting the presence of several guilds of bats as they relate to a bats’ ability to orientate and fly within a woodland. Our findings indicate that where clutter and stems per hectare are especially low or high, bat richness is markedly reduced.4.Using woodland characteristics enables practitioners to estimate bat richness at the local level where direct species sampling is not possible or as a tool to target future species surveys. Structural characteristics can be captured during forest inventories without the need for specific taxonomic expertise. Following additional ground-truthing the proposed method could be expanded to cover a broader range of habitats and fauna with general application.

Sexual segregation occurs in bats within fragmented remnant woodlands in an agricultural landscape.

Species‐specific responses to landscape configuration and landscape composition have been studied extensively. However, little work has been done to compare intraspecific differences in habitat preferences. Bats have potential as good bioindicator taxa in woodland habitats. Therefore, studying sex differences in responses to woodland and the wider landscape can allow us to gain insight into the relative importance of these habitats for both bats and other taxa. In this study, we aimed to test the predictions that (i) habitat type and connectivity will influence the probability of recording female bats in woodlands and (ii) sex differences in response to habitat type and connectivity will be species‐specific. Bat capture data was collected in 206 woodlands over 3 years in England. The probability of detecting females relative to males was modeled in response to a range of woodland characteristics and landscape metrics for six bat species. We recorded sex differences in responses to landscape features in three species. We found a higher probability of capturing female Myotis nattereri in woodlands that were surrounded by a higher proportion of improved grasslands, whereas female Myotis mystacinus were less likely to be recorded in woodlands surrounded by semi‐natural vegetation. Female Plecotus auritus were more likely to be recorded in isolated woodlands with less connectivity to other woodlands and where agriculture dominated the surrounding landscape. Our findings indicate that sexual segregation occurs across several UK bat species in response to landscape connectivity and composition. Sexual segregation in response to landscape characteristics in bats should therefore be an important consideration in the management of fragmented agricultural landscapes.

Pedological properties related to formation and functions of ancient ridge and furrow cultivation in Central and Northern Germany

Ridge and furrow cultivation is an example for a historic agriculture technique that has been very common in Germany, especially during medieval times. It seemed to be well-known how the ridge and furrows (RIFUs) were used and formed but previous studies came to contradictory conclusions which raised additional questions concerning their formation. Furthermore, the RIFUs’ morphological and physicochemical soil properties and their influence on current soils that developed after the RIFUs had been abandoned are not fully understood. In order to answer these questions, morphological and physicochemical analyses (pH, EC, TOC, TN, δ15N, C:N ratios, “Olsen P”, soil texture) were conducted on 11 preserved RIFUs in forested areas of Northern and Central Germany. The results showed that the studied RIFUs occur on sites with different properties (e.g. soil texture, inclination, vegetation) and presented various morphological shapes. They are also characterised by differences in the formation of soil horizons and general low TN (<1.5 g kg−1) and TOC (<10 g kg−1) contents. However, higher contents at some sites comparing to their references, indicated that the RIFU cultivation promoted a slight long-lasting soil improvement if not induced by secondary soil processes after RIFU use. Moreover, for some sites, high P and δ15N values may suggest the application of manure. Recent morphological changes also had a significant influence on some study sites. In summary, neither the formation and agricultural strategies of RIFU cultivation nor their function and any influences on the current soil and woodland characteristics can be regarded as identical for all RIFU sites.

The effects of thinning management on bats and their insect prey in temperate broadleaved woodland

Trees, woods, forests and associated biodiversity are being affected by anthropogenic climate breakdown, and need management to maintain delivery of a wide range of ecosystem services. Wood harvested from sustainably managed woodlands can be used to mitigate greenhouse gas emissions through carbon substitution, directly using biomass for bioenergy to replace fossil fuels or indirectly through the use of wood products instead of higher carbon footprint materials such as concrete and steel. However, it is also important to understand how managing woodlands to mitigate climate change affects biodiversity.We tested the hypotheses that thinning woodland benefits bats and their insect prey by measuring bat species/species group richness and activity, and insect species/species group richness and biomass in 27 pairs of managed and under-managed broadleaved woodlands, and explored temporal responses to time since management. Sixteen woodland characteristics were measured to investigate how management affected woodlands, and to assess the relative importance of these characteristics to bats and their insect prey.Woodland thinning significantly reduced five woodland characteristics known to be important for woodland-dwelling bats. Standing dead trees were three times more abundant, and tree cavities five times more frequent in under-managed woodland compared with managed paired sites.Woodland thinning significantly increased bat richness and activity. Common and adaptable bat species, and those that forage along woodland edges (e.g. Pipistrellus pipistrellus), were positively affected by management, presumably exploiting less cluttered woodland interiors. Rarer bat species, and species that roost predominantly in trees (e.g. Barbastella barbastellus) were negatively affected by management, which reduced roosting opportunities. Overall bat activity and species richness were relatively low in woodland that had not been thinned for 30 years before increasing. Insect biomass peaked after 30 years of no thinning.We recommend minimum intervention management to conserve rare bat species in woodlands, although common and adaptable bat species may benefit from intermediate to heavy thinning. Sustainably thinned woodland could be greatly improved for all bats by retaining or mimicking habitat characteristics that are more representative of old growth woodland such as (i) standing dead trees, (ii) tree cavities, (iii) heterogeneous canopy architecture, and (iv) an overall uncluttered below-canopy vegetation with pockets of densely cluttered shrubs.

Does ecosystem quality matter for cultural ecosystem services?

This short communication examines the relationship between nature conservation interventions aimed at enhancing ecological quality and cultural ecosystem services (CES) for human health and well-being. Using forest ecosystems as an exemplar – a system of international importance for both biodiversity and people – our UK and Ireland-focused review found little empirical evidence that incorporated a socio-ecological comparative analysis of management interventions and CES. We thus synthesised the identified literature into four themes from which to draw insight: public preferences for woodland characteristics; effects of urban/peri-urban woodlands; spiritual aspects of woodlands; and changing management paradigms. Across these bodies of literature, we found that ecological health was not the main factor underpinning CES from urban woodlands; instead social meaning, stemming from woodland experiences, was a primary factor. Despite woodlands being increasingly managed for multiple benefits, the literature provides little detail as to how native biodiverse woodlands are more beneficial than those that contain non-native species. We conclude highlighting the need for embedding a transactional socio-ecological frame that considers the interactions between people and woodlands, into both research and practice on CES and human well-being.

Habitat use and tree selection of a declining Afro-Palaearctic migrant at sub-Saharan staging and wintering sites

ABSTRACTCapsule: Wood Warblers Phylloscopus sibilatrix showed significant selection for tree species and woodland characteristics at staging and wintering sites in sub-Saharan Africa.Aims: To investigate home range size, habitat and tree species selection of Wood Warblers at a staging site in Burkina Faso (Koubri) and a wintering site in Ghana (Pepease).Methods: Comparing habitat recorded at locations of radio-tagged birds and at control points, we investigated whether there was habitat and tree species selection. We also compared home range size of individual birds between the two sites.Results: Home range size did not differ between the two sites. There was significant selection for tree species at both Koubri and Pepease: Anogeissus leiocarpus and Albizia zygia, respectively. At Koubri, there was significant avoidance of the most common tree species (Azadirachta indica, Mangifera indica (both non-native), Vitellaria paradoxa and Acacia spp.). In addition, there was a preference for taller trees and greater tree density at both sites. However, the probability of a point being used declined with increasing number of taller (>14 m) trees.Conclusion: Fine-scale selection of woodland habitats suggests that Wood Warblers are likely to suffer the consequences of ongoing land-use change in their West African wintering grounds.

Are woodland creation schemes providing suitable resources for biodiversity? Woodland moths as a case study

Woodland, like many habitats throughout the world, has been severely affected by habitat loss and fragmentation. Woodland restoration programmes aimed at reversing habitat loss have been in place in many countries over the last 100 years. In particular, agri-environment schemes (AES) to increase the amount and quality of woodland on agricultural land have operated in Europe and Australia for decades (nearly 30 years in the United Kingdom). However, to date there has been very little assessment of their value to biodiversity. We assessed the potential benefits to biodiversity of woodlands planted during 1988–1991 under a woodland grant scheme (WGS in Scotland), according to local and landscape-level habitat characteristics. Specifically, we (1) performed a linear discriminant analysis to compare the characteristics of 24 WGS sites to those of more mature semi-natural woodlands (34 sites >60 years old), and (2) used existing information on the influence of woodland characteristics on a biologically diverse group (i.e. moths) to quantify the benefits of WGS sites to biodiversity. The creation of new WGS patches increased woodland extent and connectivity in the landscape; however, planting that took place adjacent to previously existing woodland did not usually increase connectivity. WGS sites were mainly composed by broadleaved native tree species, but non-native species were also present. In general, WGS sites had lower tree species richness, proportion of native trees, tree basal area and amount of understory, and higher tree densities and canopy cover than more mature semi-natural woodlands. Overall, WGS sites were predicted to have lower moth abundance and species richness than older semi-natural woodlands. However, the magnitude of these differences depended on the habitat specificity and dispersal abilities of different moth groups, suggesting that WGS sites are better at providing suitable resources for generalist species and for species less limited by dispersal. Our findings have important implications for the way in which current woodland creation and management schemes operate in many countries and suggest that: (1) the creation of new woodlands should focus on planting native species, (2) woodland creation schemes are likely to be more beneficial for biodiversity if certain management practices (e.g. thinning to enhance structural diversity and accelerate the transition to later successional stages) accompany the provision of these grants, and (3) spatially-targeted woodland creation would further increase the contribution of AES woodlands to enhance biodiversity.

Exploratory analysis of atmospheric pollution in a coastal forest ecosystem in central Italy

Exploratory analysis of atmospheric pollution in a coastal forest ecosystem in central Italy - The study of spatial and temporal distribution of heavy metals in the atmosphere through the continuous assessment of deposition is of great interest for the analysis of anthropogenic pressure on the environment and the potential toxicity to humans and other living organisms. Information based on reliable estimates of heavy metals is therefore crucial for the evaluation of environmental quality. Trends in heavy metal concentration in atmospheric depositions on a coastal forest ecosystem (Castelporziano, Rome) are analyzed in the present study based on a three-year monitoring field survey over three sites representative of different woodland characteristics in the area. Our results highlight both the influence of transportation processes in the short and medium distance based on the human pressure reflecting urban expansion and infrastructure development on the fringe of Castelporziano pristine forest. Further studies investigating the latent correlation with meteorological variables at various temporal scales are needed to provide a comprehensive picture of environmental conditions in a forest ecosystem subjected to increasing human pressure. Analysis of runoff water quality and the determination of other heavy metals, such as arsenic, may identify additional sources of pollution impacting soil and forest ecosystem.

The value of plantation forests for plant, invertebrate and bird diversity and the potential for cross-taxon surrogacy

As the area of plantation forest expands worldwide and natural, unmanaged forests decline there is much interest in the potential for planted forests to provide habitat for biodiversity. In regions where little semi-natural woodland remains, the biodiversity supported by forest plantations, typically non-native conifers, may be particularly important. Few studies provide detailed comparisons between the species diversity of native woodlands which are being depleted and non-native plantation forests, which are now expanding, based on data collected from multiple taxa in the same study sites. Here we compare the species diversity and community composition of plants, invertebrates and birds in Sitka spruce- (Picea sitchensis-) dominated and Norway spruce- (Picea abies-) dominated plantations, which have expanded significantly in recent decades in the study area in Ireland, with that of oak- and ash-dominated semi-natural woodlands in the same area. The results show that species richness in spruce plantations can be as high as semi-natural woodlands, but that the two forest types support different assemblages of species. In areas where non-native conifer plantations are the principle forest type, their role in the provision of habitat for biodiversity conservation should not be overlooked. Appropriate management should target the introduction of semi-natural woodland characteristics, and on the extension of existing semi-natural woodlands to maintain and enhance forest species diversity. Our data show that although some relatively easily surveyed groups, such as vascular plants and birds, were congruent with many of the other taxa when looking across all study sites, the similarities in response were not strong enough to warrant use of these taxa as surrogates of the others. In order to capture a wide range of biotic variation, assessments of forest biodiversity should either encompass several taxonomic groups, or rely on the use of indicators of diversity that are not species based.

Factors influencing moth assemblages in woodland fragments on farmland: Implications for woodland management and creation schemes

As a consequence of long-term deforestation, woodland cover has been drastically reduced in the United Kingdom. The remaining woodland consists mainly of small, highly fragmented woodland patches within farmland. A number of agri-environment schemes aim to increase the amount and quality of woodland on agricultural land, but there is limited information on associations between moths and woodland characteristics which can be used to produce practical recommendations for woodland creation and management. We studied micro- and macromoth communities in woodland patches within farmland to assess the effects of woodland vegetation character and patch configuration. In addition, we measured the influence of the surrounding landscape to assess the potential importance of a landscape-scale management approach for moth conservation. In general, high tree species diversity and a high proportion of native tree species were related to higher moth abundance and species richness; there was a negative impact of grazing. Moth abundance and richness were higher in large woodland patches located close to other woodlands. Woodlands of compact shapes (with proportionally less edge exposed to the surrounding matrix) had higher numbers of ‘woodland species’, which were associated with woodland core habitat. Small woodland patches can potentially maintain relatively high moth abundance and richness, depending on their shape and proximity to other woodlands. Woodland extent was the most important landscape parameter influencing moths, mostly at relatively small spatial scales (⩽500m); macromoth ‘woodland species’ were influenced by woodland extent at larger spatial scales (⩽1500m) and are more likely to benefit from a landscape-scale management approach. Our results have important implications for the design and management of woodland patches of high conservation value within agricultural land.

Bat Response to Woodland Restoration within Urban Forest Fragments

In urban environments, woodland areas are typically fragmented and subject to invasive species encroachment, woody overgrowth, and natural succession. In response to negative impacts, conservationists and land managers have implemented restoration strategies to enhance the integrity of woodlands. Because woodland habitat is important for bats (Order Chiroptera), alterations to forest structures may affect how bats utilize forest fragments in urban environments. We evaluated relationships among restoration efforts, microhabitat characteristics and overall bat activity, and interspecific variation among bats in response to woodland characteristics. We monitored bats in nine woodland forest preserves representing various stages of restoration within the Chicago metropolitan area in 2004 and 2005. Overall bat activity was positively related to prescribed burning, invasive species removal, and small tree density (7.7-20 cm dbh) and inversely related to shrub density and clutter at 0-6 m heights. There was interspecific variation in response to alterations in woodland structure, with Lasiurus borealis (L. borealis) positively associated with small and medium (20.1-33 cm) tree densities and inversely related to clutter at 0-9 m; Myotis spp. positively associated with canopy cover, clutter at 6-9 m, and small and medium tree densities; and Lasionycteris noctivagans (L. noctivagans) positively associated with more open forests. Eptesicus fuscus (E. fuscus) activity was not strongly associated with any measured vegetation variable. Our results demonstrate bats positively respond to some forms of woodland restoration in urban landscapes. However, species-specific responses to vegetation differed and should be taken into consideration when developing management plans.

Habitat selection and diet of the Capercaillie Tetrao urogallus in Abernethy Forest, Strathspey, Scotland

Capsule Woodland characteristics are important for fully grown birds and for broods. Aims To describe habitat selection and diet of the Capercaillie in ancient native pinewoods and Scots Pine Pinus sylvestris plantations, in order to provide a guide for forest management. Methods Tree selection was studied in winter by locating droppings under trees along transects, and comparing those trees used by Capercaillie with those not used. Habitat selection by broods was studied by following radiotagged chicks or females with broods. Diet was described from the analysis of droppings. Results In winter, Capercaillie preferred Scots Pines with wide crowns and large branches, and little surrounding Heather Calluna vulgaris, but avoided forest tracks. Female Capercaillie occurred in stands with a higher density of pines compared to males. The diet of fully grown birds comprised primarily Scots Pine needles between October and April. Scots Pine pollen cones were eaten during May, June and July. Bilberry Vaccinium myrtillus leaves and fruit were eaten in summer and autumn. Habitats used by broods had a higher percentage of Vaccinium sp. and smaller Scots Pines compared with random sites. Chicks hatch at the beginning of June, and in their first two weeks, their diet comprised Formicidae, Lepidoptera larvae and Coleoptera. In July and August, Lepidoptera larvae were rarely eaten but a higher percentage of chicks took vegetable material (particularly Bilberry fruit). In June, smaller numbers of invertebrates were generally trapped in mires of wooded bogs compared with areas of Heather and Vaccinium sp. in old woodland. Areas of Vaccinium sp. had the highest numbers of Formicidae, Coleoptera and Diptera, and especially Lepidoptera larvae. Numbers of Lepidoptera larvae declined during June and July as larvae pupated, explaining the reduction of Lepidoptera larvae in the diet of older chicks. Conclusions Habitat management for Capercaillie should aim to provide old Scots Pine forest with a Vaccinium-rich field layer. Within Scotland, this may entail increasing the tree density in ancient native pinewoods but decreasing it in pine plantations. The removal or closure of tracks might increase the amount of woodland available to Capercaillie, by reducing human disturbance.

A national perspective on recent changes in the spatial characteristics of woodland in the British landscape

In this paper, we assessed to what extent the overall increase in woodland area observed in Great Britain over the last 20 years (about 9%) has modified the distribution and spatial characteristics of woodland at the landscape level. Field mapping data recorded in 1984 and 1998 during the national monitoring programme Countryside Survey were analysed for the six main regions of Great Britain. Results indicate that, woodland patches are very dynamic features in the British landscape, hence contradicting the widely shared view that woodland are stable elements in a landscape. It also appeared that the net increase in woodland density observed across regions hid important turnovers and that a substantial number of existing woodland patches, some of them probably quite ancient, were either removed or suffered from shrinkage. Gains in woodland density resulted as much from the proliferation of newly planted patches than from the expansion of existing patches, hence a relatively limited increase in average patch size. It, therefore, appears that the increase in total area of woodland in Britain has not stopped the continuous loss of old woodland and has only led to little de-fragmentation.

The representation of taxa in surface pollen spectra on alpine and sub-alpine glacier forelands in southern Norway

The relationship between vegetation and surface pollen deposition is examined in a range of alpine and sub-alpine plant communities on 26 glacier forelands in southern Norway. Plant–pollen relationships of individual taxa are emphasised, particularly herb taxa which have rarely been considered quantitatively. Three categories of pollen taxa can be recognised: (1) Mostly insect-pollinated taxa showing relatively strong plant–pollen correlations (e.g. Empetrum, Oxyria and Salix); (2) Wind-pollinated taxa, such as Betula, Pinus and Gramineae, that show a very poor correlation; and (3) Herb taxa that produce relatively little pollen and rarely register in the pollen spectrum.For example, total Ericales has a plant–pollen correlation coefficient as high as 0.74 and it’s pollen frequencies are ten-fold higher where the plant is present than where it is absent. This contrasts with wind-pollinated taxa such as Gramineae that has a correlation coefficient of 0.37 and has no statistical difference in pollen frequencies between sites where the plant occurs and sites where it is absent. Regional scale plant–pollen relationships, for most taxa, are similar to relationships at the scale of the single glacier foreland.An additional study was made of the impact of local woodland on the composition of surface pollen spectra. The relationship was examined between local woodland characteristics, tree height and girth, woodland density and canopy cover and tree pollen at nine sub-alpine glacier forelands (312 trees measured at 36 sampling sites). A clear negative correlation was found between both Betula and total arboreal pollen frequency with tree height and tree girth, suggesting that woodland filters out regional tree pollen and that the local pollen contribution is relatively unimportant.This study provides potentially valuable analogues for early Holocene successional stages from elsewhere in Europe. The proportion of pollen with a regional source may have been underestimated in some previous studies. It is suggested that relatively rare herb pollen taxa should be given greater consideration, since they provide valuable indications of the composition of the local plant community, past and present.

The role of protective understorey in the regeneration system of a heavily browsed woodland

The paper tests an apparent relationship between young understorey of Ilex aquifolium and the presence of seedlings of the canopy species Fagus sylvatica and Quercus species, in heavily browsed woodland in the New Forest, southern England. A small block of woodland was searched and mapped, and the information collected subject to graphical and statistical analyses. Regeneration, though of low frequency, is present and shows non-random patterns of distribution. Older seedlings appear to be located in or near areas of understorey, or near fallen branches, logs, etc. Principal components analysis of woodland characteristics suggests six main habitat types are available to seedlings, and predictions are made about likely regeneration patterns associated with these habitats, according to a model based on the hypothesis of a protective understorey and heavy browsing pressure. Chi-square tests of actual seedling occurrences versus habitat types demonstrate marked associations of regeneration with non-trampled areas, including young Ilex understorey but also other forms of protective barrier. The association is more marked for larger seedlings. The implications for a wider understanding of regeneration processes and community dynamics in heavily browsed forest are discussed. It is concluded that regeneration theories appropriate to such forests are required, since the dominant gap-phase theories are not successful in predicting regeneration patterns when browsing is a major factor.

Seasonal population changes of myxomycetes and associated organisms in five non-woodland soils, and correlations between their numbers and soil characteristics

Microbial populations and other characteristics of five non-woodland soils from sites in the West of England were studied quantitatively over the course of a year, and special attention was paid to the changing abundance of myxomycetes. The latter, expressed as numbers of plasmodium-forming units (PFUs), were on average more abundant than in three representative woodland soils. During the year, instances were recorded in which rapidly increasing populations of bacteria were accompanied by increasing numbers of phagotrophic microorganisms, including myxomycetes, and others in which rapidly increasingly populations of phagotrophs were accompanied by falls in the numbers of bacteria. Oscillating predator-prey relationships were suggested. Myxomycetes were generally a significant component of the phagotrophic populations, even exceeding 50% of the total soil naked amoebae. Data on the biological and abiotic characteristics of woodland [3] and non-woodland soils were combined and statistically analysed for correlations. Myxomycete abundance was positively correlated with numbers of soil amoebae, ciliates, total bacteria, myxobacteria and nematodes, but inversely correlated with numbers of dictyostelid cellular slime moulds. It was positively correlated with soil pH and level of potassium, and negatively correlated with moisture content, organic matter content, and nitrogen/phosphorus ratio. Calculations suggest that the biomass of myxomycetes in temperate soils is commonly 6.4–64 mg dry weight · m −2.

Seasonal population changes of myxomycetes and associated organisms in five non-woodland soils, and correlations between their numbers and soil characteristics

Microbial populations and other characteristics of five non-woodland soils from sites in the West of England were studied quantitatively over the course of a year, and special attention was paid to the changing abundance of myxomycetes. The latter, expressed as numbers of plasmodium-forming units (PFUs), were on average more abundant than in three representative woodland soils. During the year, instances were recorded in which rapidly increasing populations of bacteria were accompanied by increasing numbers of phagotrophic microorganisms, including myxomycetes, and others in which rapidly increasingly populations of phagotrophs were accompanied by falls in the numbers of bacteria. Oscillating predator-prey relationships were suggested. Myxomycetes were generally a significant component of the phagotrophic populations, even exceeding 50% of the total soil naked amoebae. Data on the biological and abiotic characteristics of woodland [3] and non-woodland soils were combined and statistically analysed for correlations. Myxomycete abundance was positively correlated with numbers of soil amoebae, ciliates, total bacteria, myxobacteria and nematodes, but inversely correlated with numbers of dictyostelid cellular slime moulds. It was positively correlated with soil pH and level of potassium, and negatively correlated with moisture content, organic matter content, and nitrogen/phosphorus ratio. Calculations suggest that the biomass of myxomycetes in temperate soils is commonly 6.4–64 mg dry weight · m−2.