Changes In Individual Species Research Articles

Plant communities in drainage ditches – conditions, characteristics and environmental functions

Ditches and drainage canals are an important element in the post-bog meadows. Their basic function is to regulate air-water relations in ecosystems, mainly in agrocenoses. The environmental functions of ditches and canals consist of maintaining a large diversity of flora and fauna species due to high humidity of these ecosystems. The study of plant communities in the ditches in the post-bog meadows habitat of the Supraśl Dolna valley structure in 2010–2020 was carried out. There were 23–27 species of plants in the ditches. Species diversity did not change significantly during this period, while changes in individual species’ coverage and viability were found. The species were classified into two rush communities: reed rush ( Phragmitetum australis) and rush ( Phalaridetum arundinaceae). As a result of the lack of maintenance of the ditches, an invasive species of flapped barbed ( Echinocystis lobata) was found. The natural valorization carried out by the Oświt method showed that plant communities in the drainage ditches are in the lowest valorization classes.

High-resolution mass spectrometric analysis of cardiolipin profiles in Barth syndrome

Barth syndrome is an X-linked recessive disorder caused by pathogenic variants in TAZ, which leads to a reduction in cardiolipin with a concomitant elevation of monolysocardiolipins. There is a paucity of studies characterizing changes in individual species of monolysocardiolipins, dilysocardiolipins and cardiolipin in Barth syndrome using high resolution untargeted lipidomics that can accurately annotate and quantify diverse lipids. We confirmed the structural diversity monolysocardiolipins, dilysocardiolipins and cardiolipin and identified individual species that showed previously unreported alterations in BTHS. Development of mass spectrometry-based targeted assays for these lipid biomarkers should provide an important tool for clinical diagnosis of Barth syndrome.

Which Traits Influence Bird Survival in the City? A Review

Urbanization poses a major threat to biodiversity worldwide. We focused on birds as a well-studied taxon of interest, in order to review literature on traits that influence responses to urbanization. We review 226 papers that were published between 1979 and 2020, and aggregate information on five major groups of traits that have been widely studied: ecological traits, life history, physiology, behavior and genetic traits. Some robust findings on trait changes in individual species as well as bird communities emerge. A lack of specific food and shelter resources has led to the urban bird community being dominated by generalist species, while specialist species show decline. Urbanized birds differ in the behavioral traits, showing an increase in song frequency and amplitude, and bolder behavior, as compared to rural populations of the same species. Differential food resources and predatory pressure results in changes in life history traits, including prolonged breeding duration, and increases in clutch and brood size to compensate for lower survival. Other species-specific changes include changes in hormonal state, body state, and genetic differences from rural populations. We identify gaps in research, with a paucity of studies in tropical cities and a need for greater examination of traits that influence persistence and success in native vs. introduced populations.

Use of an oxygen planar optode to assess the effect of high velocity microsprays on oxygen penetration in a human dental biofilms in-vitro

BackgroundDental plaque biofilms are the causative agents of caries, gingivitis and periodontitis. Both mechanical and chemical strategies are used in routine oral hygiene strategies to reduce plaque build-up. If allowed to mature biofilms can create anoxic microenvironments leading to communities which harbor pathogenic Gram-negative anaerobes. When subjected to high velocity fluid jets and sprays biofilms can be fluidized which disrupts the biofilm structure and allows the more efficient delivery of antimicrobial agents.MethodsTo investigate how such jets may disrupt anoxic niches in the biofilm, we used planar optodes to measure the dissolved oxygen (DO) concentration at the base of in-vitro biofilms grown from human saliva and dental plaque. These biofilms were subject to “shooting” treatments with a commercial high velocity microspray (HVM) device.ResultsHVM treatment resulted in removal of much of the biofilm and a concurrent rapid shift from anoxic to oxic conditions at the base of the surrounding biofilm. We also assessed the impact of HVM treatment on the microbial community by tracking 7 target species by qPCR. There was a general reduction in copy numbers of the universal 16S RNA by approximately 95%, and changes of individual species in the target region ranged from approximately 1 to 4 log reductions.ConclusionWe concluded that high velocity microsprays removed a sufficient amount of biofilm to disrupt the anoxic region at the biofilm-surface interface.

The decline in plant biodiversity slows down soil carbon turnover under increasing nitrogen deposition in a temperate steppe

Abstract Nitrogen (N) deposition not only alters the physiological processes of individual plant, but also leads to world‐wide biodiversity loss. However, little is known about how the hierarchical responses from individual physiological processes to plant community structure would have cascading effects on soil carbon (C) cycling. Here, we assessed whether changes in plant chemical composition and community composition under increasing N input would affect the turnover rate of litter layer and soil C loss via heterotrophic respiration (Rh) in a temperate grassland. We showed that more than a decade’s N addition significantly decreased plant species richness, litter layer turnover rate and Rh. The 13C‐NMR results showed that, for individual species, N addition either increased the abundance of recalcitrant C groups such as alkyl and methoxyl, or decreased labile C groups such as carbohydrate, resulting in decreases in carbohydrate C‐to‐methoxyl C ratio (CC/MC) for most species. Our data also showed that with the increase in N deposition, the abundance of relatively high degradable dominant species, such as Agropyron cristatum and Artimesia frigida declined rapidly, and the relatively recalcitrant species such as Potentilla bifurca and Leymus chinensis become dominant. Changes in individual species’ chemical composition and plant community composition significantly decreased litter quality at community level, as indicated by the lower community‐level CC/MC at higher N addition rates. The result of step‐AIC model selection further showed that plant diversity loss and the decrease in community‐level CC/MC jointly explained the decrease in Rh after N addition best, and further relative importance partition result showed that these two factors respectively contributed 65.1% and 34.9% of the explained variation. Overall, we demonstrated that changes in plant chemical composition and diversity loss due to N addition reduced the quality of plant C input to soil, which further slowed down litter layer turnover rate and inhibited soil heterotrophic respiration. Our study complements the intermediate links of how shifts in plant community structure regulate soil C cycle under global changes. A plain language summary is available for this article.

Autochthonous yeasts as one of the tools to produce wines by original technologies

This review focuses on autochthonous wine yeasts that occur naturally in a specific geographical area, and their role in wine production. The distribution of individual species changes during ripening and processing of grapes and fermentation of the grape must. The composition of autochthonous microflora is influenced by many factors including interspecific interactions. Autochthonous yeast populations lend to wine flavor and taste typical for a specific geographical area. The article describes the fermentation of grape must, changes of autochthonous yeast microflora during spontaneous or combined fermentation, and includes an overview of the basic species of autochthonous yeasts.

Importance of Natura 2000 sites for wintering waterbirds: Low preference, species' distribution changes and carrying capacity of Natura 2000 could fail to protect the species

Evaluating the species use of protected area networks is of considerable worldwide importance, especially as a feedback for policy-makers and the conservation community. Based on the data of an annual, citizen-science monitoring programme of long tradition (2004–2015), we test the hypothesis that the European Natura 2000 network protects high quality habitats preferentially settled by wintering waterbird species in a central European State (the Czech Republic). We analysed species-specific variables (protection status, flyway population trend and numbers, geographical distribution, and foraging guild) explaining the proportions of numbers in Natura 2000 and individual-species changes in numbers inside and outside Natura 2000. The proportions of numbers in individual species were generally low in Natura 2000 sites. The observed pattern revealed the expected higher preference of protected Annex I species for Natura 2000 sites compared to other species and showed foraging guilds having significant differences in Natura 2000 preference, with high preference in herbivores and fish-eaters and low preference in invertebrate-eaters compared to omnivores. Northern species also showed a high preference for Natura 2000. The predicted prevalence of a higher rate of increase, or lower rate of decrease, inside Natura 2000, indicating that Natura 2000 facilitated the species' distribution changes, was not shown; instead, the positive and negative trends inside Natura 2000 were almost equivalent. We concluded that the low preference for Natura 2000, the distribution changes shifting species outside Natura 2000, and limits to the carrying capacity of the protected network sites, could all make an issue in effectively safeguarding the non-breeding populations of waterbirds. The extension of the Natura 2000 network to facilitate their wintering requirements and distribution changes is therefore a high priority.

Drivers of inter-annual variation and long-term change in High-Arctic spider species abundances

Understanding how species abundances vary in space and time is a central theme in ecology, yet there are few long-term field studies of terrestrial invertebrate abundances and the determinants of their dynamics. This is particularly relevant in the context of rapid climate change occurring in the Arctic. Arthropods can serve as strong indicators of ecosystem change due to their sensitivity to increasing temperatures and other environmental variables. We used spider samples collected by pitfall trapping from three different habitats (fen, mesic and arid heath) in High-Arctic Greenland to assess changes in individual species abundances over an 18-year period (1996–2014). We calculated annual abundances of each species using a conventional method and compared this to a technique that corrected for the influence of short-term weather variation on arthropod activity. The latter method used the area under the curve of a fitted generalized additive model to measure annual change in abundance of each species. Abundances calculated using each of the two methods did not differ greatly over time nor in direction of climate effects, suggesting that short-term weather-driven activity does not influence interpretation of long-term trends. We used model selection to determine which climatic variables and/or previous years’ abundance best explained annual variation in species abundances over this period. We identified and used 28 566 adult spiders that comprised eight species. Most notably, the abundances of some species (Collinsia thulensis and Erigone psychrophila) have declined during this 18-year period, in response to rising temperatures and snow depth dynamics, which affected snowmelt timing and moisture availability. No species increased in abundance through the study period. Since some species showed no trend in abundance through time and climatic effects were habitat-specific, continued climate change may also affect local species interactions. Long-term monitoring programmes are an extremely valuable means through which to generate empirical data about changes in populations and communities; this is especially pertinent in the Arctic, where climate change is occurring at a rapid rate.

Factors controlling the depth habitat of planktonic foraminifera in the subtropical eastern North Atlantic

Abstract. Planktonic foraminifera preserved in marine sediments archive the physical and chemical conditions under which they built their shells. To interpret the paleoceanographic information contained in fossil foraminifera, the recorded proxy signals have to be attributed to the habitat and life cycle characteristics of individual species. Much of our knowledge on habitat depth is based on indirect methods, which reconstruct the depth at which the largest portion of the shell has been calcified. However, habitat depth can be best studied by direct observations in stratified plankton nets. Here we present a synthesis of living planktonic foraminifera abundance data in vertically resolved plankton net hauls taken in the eastern North Atlantic during 12 oceanographic campaigns between 1995 and 2012. Live (cytoplasm-bearing) specimens were counted for each depth interval and the vertical habitat at each station was expressed as average living depth (ALD). This allows us to differentiate species showing an ALD consistently in the upper 100 m (e.g., Globigerinoides ruber white and pink), indicating a shallow habitat; species occurring from the surface to the subsurface (e.g., Globigerina bulloides, Globorotalia inflata, Globorotalia truncatulinoides); and species inhabiting the subsurface (e.g., Globorotalia scitula and Globorotalia hirsuta). For 17 species with variable ALD, we assessed whether their depth habitat at a given station could be predicted by mixed layer (ML) depth, temperature in the ML and chlorophyll a concentration in the ML. The influence of seasonal and lunar cycle on the depth habitat was also tested using periodic regression. In 11 out of the 17 tested species, ALD variation appears to have a predictable component. All of the tested parameters were significant in at least one case, with both seasonal and lunar cyclicity as well as the environmental parameters explaining up to > 50 % of the variance. Thus, G. truncatulinoides, G. hirsuta and G. scitula appear to descend in the water column towards the summer, whereas populations of Trilobatus sacculifer appear to descend in the water column towards the new moon. In all other species, properties of the mixed layer explained more of the observed variance than the periodic models. Chlorophyll a concentration seems least important for ALD, whilst shoaling of the habitat with deepening of the ML is observed most frequently. We observe both shoaling and deepening of species habitat with increasing temperature. Further, we observe that temperature and seawater density at the depth of the ALD were not equally variable among the studied species, and their variability showed no consistent relationship with depth habitat. According to our results, depth habitat of individual species changes in response to different environmental and ontogenetic factors and consequently planktonic foraminifera exhibit not only species-specific mean habitat depths but also species-specific changes in habitat depth.

Food‐web composition and plant diversity control foliar nutrient content and stoichiometry

Summary The content and ratio of nutrients in plants can be constrained by a wide array of factors, including nutrient supply, light intensity, herbivory, infection or intrinsic growth rate and can, in turn, affect many ecosystem processes including photosynthesis, decomposition, resource limitation and nutrient cycling. Studies of plant stoichiometry and stoichiometric homeostasis have focused primarily on the role of nutrient supply as a constraint on plant tissue chemistry, yet recent work suggests that local plant diversity, plant species composition and consumers may change the nutrient composition of whole plant communities. By experimentally removing insects, foliar fungi and soil fungi from a long‐term experiment manipulating plant diversity, we found that the foliar stoichiometry of individual plant species depends on biotic context. Local plant diversity and the composition of the consumer community each altered foliar tissue carbon and nutrient chemistry of four different grassland species. The greatest impacts of consumers on foliar chemistry occurred at low plant diversity, and these changes induced by altering the food web were of a similar magnitude to the effects of fertilization or drought found in previous work. Consumers and plant diversity acted primarily on foliar carbon and nitrogen, whereas changes in foliar phosphorus were associated with the productivity of the local plant community. Thus, changes in whole‐community stoichiometry that have been documented in response to alterations of the consumer food web or plant community are underlain by stoichiometric changes in individual species as well as plant species compositional changes. Synthesis. These results suggest a new pathway by which loss of consumer or plant diversity may significantly impact the wide variety of ecosystem processes that depend on foliar nutrient content.

Temporal change in the herbaceous understory community of an old-growth forest: from seasons to decades

Studies focusing on the herbaceous groundlayer of forest communities have become increasingly common in the literature, yet rarely do these studies adequately capture the temporal dynamics that typify this stratum. Using long-term data from an old-growth remnant stand in southeastern Ohio, we compare seasonal, annual, and decadal changes in herb composition and abundance on a north- and south-facing slope. Herbs were sampled within 70, 2-m2 circular plots at three times throughout the growing season in 1997, 1998, 2011, and 2012. Slope, season, and year all had significant effects on species composition, as did their interactions. Species richness and diversity varied considerably throughout seasons, yet remained consistent over the fifteen-year study interval. A dramatic reduction in overall abundance, from an average of 63 % in 1997 to just 12 % in 2012, was observed. This decline was most severe from 1997 to 1998. A nonmetric multidimensional scaling ordination for all 4 years showed a collapse in phenological distinction among seasonal-sampling units. Finally, we looked at year-to-year changes in individual species abundances by comparing occurrence frequencies. The frequency of a species in year i was usually a good indicator of its frequency in year j; however, a few species showed considerable increases or decreases, such as the invasive Alliaria petiolata, which increased from zero plots in 1997 to 15 plots in 2012. These results suggest the importance of adequately and simultaneously documenting vegetation changes at short, intermediate, and long-term timescales—especially for understanding the dynamics of temperate deciduous forest herb communities.

PPARG Binding Landscapes in Macrophages Suggest a Genome-Wide Contribution of PU.1 to Divergent PPARG Binding in Human and Mouse

BackgroundGenome-wide comparisons of transcription factor binding sites in different species can be used to evaluate evolutionary constraints that shape gene regulatory circuits and to understand how the interaction between transcription factors shapes their binding landscapes over evolution.ResultsWe have compared the PPARG binding landscapes in macrophages to investigate the evolutionary impact on PPARG binding diversity in mouse and humans for this important nuclear receptor. Of note, only 5% of the PPARG binding sites were shared between the two species. In contrast, at the gene level, PPARG target genes conserved between both species constitute more than 30% of the target genes regulated by PPARG ligand in human macrophages. Moreover, the majority of all PPARG binding sites (55–60%) in macrophages show co-occupancy of the lineage-specification factor PU.1 in both species. Exploring the evolutionary dynamics of PPARG binding sites, we observed that PU.1 co-binding to PPARG sites appears to be important for possible PPARG ancestral functions such as lipid metabolism. Thus we speculate that PU.1 may have guided utilization of these species-specific PPARG conserved binding sites in macrophages during evolution.ConclusionsWe propose a model in which PU.1 sites may have served as “anchor” loci for the formation of new and functionally relevant PPARG binding sites throughout evolution. As PU.1 is an essential factor in macrophage biology, such an evolutionary mechanism would allow for the establishment of relevant PPARG regulatory modules in a PU.1-dependent manner and yet permit for nuanced regulatory changes in individual species.

Population trends of European common birds are predicted by characteristics of their climatic niche

AbstractTemperate species are projected to experience the greatest temperature increases across a range of modelled climate change scenarios, and climate warming has been linked to geographical range and population changes of individual species at such latitudes. However, beyond the multiple modelling approaches, we lack empirical evidence of contemporary climate change impacts on populations in broad taxonomic groups and at continental scales. Identifying reliable predictors of species resilience or susceptibility to climate warming is of critical importance in assessing potential risks to species, ecosystems and ecosystem services. Here we analysed long‐term trends of 110 common breeding birds across Europe (20 countries), to identify climate niche characteristics, adjusted to other environmental and life history traits, that predict large‐scale population changes accounting for phylogenetic relatedness among species. Beyond the now well‐documented decline of farmland specialists, we found that species with the lowest thermal maxima (as the mean spring and summer temperature of the hottest part of the breeding distribution in Europe) showed the sharpest declines between 1980 and 2005. Thermal maximum predicted the recent trends independently of other potential predictors. This study emphasizes the need to account for both land‐use and climate changes to assess the fate of species. Moreover, we highlight that thermal maximum appears as a reliable and simple predictor of the long‐term trends of such endothermic species facing climate change.

Recovery of sandy beach and maritime forest vegetation on Phuket Island (Thailand) after the major Indian Ocean tsunami of 2004

AbstractQuestion: How rapidly has the sandy beach and maritime forest vegetation on Phuket recovered and regenerated after the impact of the major Indian Ocean tsunami of 2004? What are the characteristics of sandy beach species for regenerating their populations and the invasion patterns of originally non‐sandy beach species or other newcomers after the tsunami?Location: Phuket Island, southern Thailand.Methods: Species composition of beaches was studied on the same research plots 6 months before and 9 months after the tsunami. The changes in individual species cover before and after the tsunami were determined by χ2 tests. Change in community composition was analysed by detrended correspondence analysis. The relationship between species and environmental factors was analysed by canonical correspondence analysis.Results: The sites disturbed by the tsunami were often invaded by annuals, especially grasses and asteraceous plants, rather than by perennials. In contrast, species with clonal growth by stolons decreased significantly. Factors determining the species habitat differences were soil hardness (penetration resistance of sandy soil), per cent silt content, soil water content and beach management. Habitat differences among originally non‐sandy beach herbaceous species that expanded their population or moved to the coast after the disaster were defined by sand accretion or erosion caused by the tsunami. Many sandy beach herbaceous communities changed into Dactyloctenium aegyptium communities because of the tsunami were originally constituted by non‐sandy beach D. aegyptium with Cenchrus echinatus. Although the forest floors of most maritime forests were invaded by originally non‐sandy beach Tridax procumbens, Eleusine indica or D. aegyptium because of the tsunami, this did not result in a change in the vegetation unit, because species' loss was restricted to the understorey. In time, these forests will recover their previous community composition.Conclusions: Our results suggest that originally non‐sandy beach native species invaded the disturbed beaches rapidly after the tsunami but their habitats differ. Sites where sand accumulated on a beach because of the tsunami were invaded by D. aegyptium and E. indica, whereas soil erosion permitted invasion by Digitania adscendens. Tridax procumbens establishes rapidly on wet sites with hard soil, high per cent silt content and low beach management pressure. Sandy beach species with subterranean long rhizomes are strongly tolerant of such disasters. We concluded that the species composition of the beaches disturbed by a temporary large disaster is determined by dormancy and growth forms, with radicoid form being influential.

Kinetic modeling of thermal cracking reactions

This paper provides a kinetics model for thermal cracking of various oils over time frames which correspond to the long term storage at temperatures up to those experienced in an in situ combustion process. The model describes detailed kinetic mechanisms and concentration changes of individual species during the thermal cracking reactions. Also the modeling results are compared with the experimental data to verify their validity.

Faunal relationships with seagrass habitat structure: a case study using shrimp from the Indo-Pacific

Caridean shrimp were used as a model group to investigate the effects of seagrass floral habitat complexity on Indo-Pacific fauna. Relationships between shrimp and seagrass habitat characteristics were explored using both multivariate and multiple linear regression modelling approaches. Epifaunal shrimp assemblages were sampled in the Wakatobi Marine National Park, Indonesia. Seagrass habitat complexity had a significant positive impact on shrimp abundance (F3,59 = 17.51, P < 0.001) and species richness (F3,59 = 10.88, P < 0.001), while significantly altering shrimp assemblage structure (ANOSIM global R = 0.397, P < 0.001). In contrast to studies from other bioregions and faunal groups, species diversity and evenness were inversely related to habitat complexity. Changes in shrimp abundance, diversity and assemblage structure with habitat complexity are considered to reflect changes in individual species habitat specialisation. High complexity habitats were dominated by habitat specialists, whereas low complexity seagrass had higher numbers of habitat generalists. Generalist species may be more adapted to the reduced food availability and increased predatory pressures associated with reduced habitat complexity. Although similar patterns were observed at all sites, inter-site differences in shrimp abundance were observed. This indicates that although the present study demonstrates the importance of small-scale changes in seagrass habitat complexity to faunal assemblages, other factors related to larger spatial-scales are also important.

ASSESSING AND MONITORING ECOLOGICAL COMMUNITY HEALTH IN MARINE SYSTEMS

The increased potential for long‐term degradative change associated with large‐scale diffuse impacts in urban marine environments highlights the need to develop methods for assessing the ecological significance of any observed changes. This study defines “health” on the basis of the range of communities observed along gradients of anthropogenic impacts. This definition identifies both acute effects and broader scale degradation in community structure. Three multivariate constrained ordination techniques were used to assess changes in communities occurring along an anthropogenic disturbance gradient of stormwater pollution in two different habitats (estuaries and harbors). All three techniques detected changes, even when historical data sets, not specifically designed for the purpose, were utilized. Comparison with five diversity indices suggested that the multivariate approach was more successful in defining change and, thus, ecological health. Moreover, the information can easily be examined for changes in individual species, or for changes in function, trophic status, or biomass/size structure, improving interpretation of the ecological consequences of change. As this multivariate approach allows for monitoring community composition to determine whether sites are improving or degrading over time, it would be useful for aiding management decisions and assessing the efficiency of management actions. While this study occurred in one region only, the approach should be able to be utilized in other marine (or freshwater or terrestrial) systems where commensurable regional‐scale multivariate databases exist.

Identification of the spectral characteristics of British semi-natural upland vegetation using direct ordination: a case study from Dartmoor, UK

The direct ordination technique Canonical Correspondence Analysis (CCA) is applied to the examination of the relationships between the floristic composition of semi-natural vegetation and its spectral reflectance. Paired measurements of floristic and spectral characteristics, the latter being measured using a portable field spectrometer, were collected at ground level for a range of upland semi-natural vegetation within two study sites on Dartmoor, south-west England. The spectral data were converted to simulate a Compact Airborne Spectrographic Imager (CASI) bandset. Both floristic and spectral data sets were then jointly ordinated using CCA. A sequence of individual species changes along the first ordination axis was identified that showed a strong correspondence with variation in the simulated CASI wavebands covering the 736 nm to 870 nm wavelengths. A significant relationship between first axis CCA scores for quadrats and their estimated total percentage vegetation cover was also identified. Although UK National Vegetation Classification (NVC) categories corresponded to a general sequence of plant community types along the first CCA axis, with the possible exception of the U20 Pteridium aquilinum-dominated community, it proved impossible to demonstrate any close link between any specific plant community type and a distinct set of spectral characteristics because of the continuum nature of the vegetation. The second axis of the CCA showed no interpretable relationship with variation in floristic/spectral data and this was confirmed further by use of Detrended Canonical Correspondence Analysis (DCCA). Possibilities for further research into floristic/spectral data using CCA/DCCA are discussed.

Changes in stand composition and structure between 1981 and 1996 in four Front Range plant communities in Colorado

We conducted a study analyzing the vegetation dynamics in four communities along an elevational gradient in the Front Range of the Colorado Rocky Mountains and compared our results with previous research conducted in 1981. The objective of this study was to determine whether the successional plant community trajectories hypothesized by the original investigator (Marr) in 1953 were consistent with plant community parameters measured in subsequent years. The ponderosa pine and Douglas-fir/ponderosa pine communities’ herbaceous composition remained relatively constant between 1981 and 1996; however, a few individual species in both communities experienced significant changes in frequency over time. These individual species changes, along with dominant shifts in the forest canopy, were inconsistent with Marr’s original successional hypotheses for these stands that stated the ponderosa pine stand would remain dominated by ponderosa pine and grassy openings and the Douglas-fir/ponderosa pine stand would eventually have equal dominance between the two tree species. The aspen herbaceous community experienced the most significant change between 1981 and 1996. Significant decreases in species richness and diversity were recorded along with large changes in species composition and frequencies of individual species. These changes were associated with successional changes in the forest canopy, which was congruent with Marr’s successional hypothesis for this stand. The kobresia meadow herbaceous community showed the least change between 1981 and 1996 among the four communities; however, there was variation in frequency percentages for a few individual species over time and a small turnover in species composition. Marr’s hypothesis that this stand represented a climax community is consistent with our results.

Impacts of deer herbivory on ground vegetation at Wytham Woods, central England

Between 1974 and 1992 there were declines in bramble ( Rubus fruticosus agg.) and several woodland forbs and an increase in grasses at Wytham Woods. These changes have been explained as effects of increasing deer populations. We set out to test this by establishing exclosure experiments in the summer of 1997. Comparison of permanent vegetation monitoring plots inside and outside the exclosures, showed that forbs tended to increase inside exclosures whilst decreasing in the wider wood, supporting the hypothesis that deer herbivory was responsible for the change. Changes in individual species were not, however, significant and it may take many years for the vegetation in the exclosures to reach a new equilibrium. In contrast to exclosures under the woodland canopy, additional exclosures in a clearing have been rapidly colonized by bramble. It appears there is an interaction between solar radiation and herbivory and the decline of bramble at Wytham may reflect canopy closure as well as deer herbivory. Faecal pellet counts made in Environmental Change Network monitoring plots between August 1998 and April 1999 indicated different habitat use by fallow ( Dama dama ) and muntjac ( Muntiacus reevesi ) deer. Grasslands in proximity to the woodland tended to accumulate proportionally more fallow deer faeces, whilst dense ancient woodland areas tended to accumulate more muntjac faeces. There was, however, little evidence of an association between particular species of plant and differential habitat use by deer.