High Nature Conservation Research Articles

Water usage and seasonality as primary drivers of benthic diatom assemblages in a lowland reservoir

Abstract In general, reservoirs are multi-purpose objects and they often have to fulfil different tasks at the same time. The compliance with these different expectations is more manageable in reservoirs with well-separated heterogeneous basins than in homogenous ones. The Kiskore Reservoir is the second largest standing water in the Carpathian Basin. Its water level is artificially regulated which creates unique habitats with high nature conservation value. Furthermore, the Reservoir is also considered as an important recreation centre in the region. It consists of four basins with different protection degree and management strategy. Here, we tested whether spatial (usage-dependent) or seasonal (time-dependent) segregations characterized the benthic diatom composition in the Reservoir. We also tested the influence of different water usage of basins using diatom metrics and diversity indices. We hypothesized that spatial heterogeneity in diatom composition will be more pronounced than seasonal ones. We also supposed that composition and diversity of diatom assemblages as well as diatom based ecological status will clearly reflect to different management strategies in the basins, whereas we expected moderate ecological status and low diversity in basins with high level of human impact. Our first hypothesis was not confirmed by the results. While diatom composition was clearly heterogeneous in time, surprisingly no usage-dependent segregation was found. Furthermore, our second hypothesis was also only partially confirmed by the results. In early summer, diversity was significantly lower in basins with higher level of human impact, than in the other basins. In late summer, however, diversity was rather directly controlled by nutrients and light not by water usage. Moreover, diatom based ecological status positively correlated to the intensity of recreation activities and negatively to protection degree. Although these results were surprising at the first time, they clearly confirm that a balanced ecological-economical relation can be maintained with properly designed and performed strategies in artificial reservoirs. But protection strategies, because of their exclusive interest to habitat conservation of macroscopic not microscopic organisms, require careful revisions.

Drivers of Land Abandonment in the Irish Uplands: A Case Study

Abstract Land abandonment is a complex multi-dimensional process with interlinked economic, environmental and social aspects. This paper presents a case study of an isolated hill sheep farming community in SW Ireland, where a combination of low incomes, ageing population, lack of successors and strong environmental constraints are perceived to be among the main factors leading to their demise. However, the uplands they have grazed for generations are of high nature conservation value, and depend on active management to maintain both their ecology and landscapes. The research, which is based on a combination of interviews and farming systems research, highlights the misfit between what the mountain can produce, light hill lamb, and what the globalised market demands. The paper argues that if ‘farming for conservation’ is the new function of such farming systems, then we should consider decoupling public goods payments from agricultural subsidies, along with integrating agriculture in disadvantaged areas within a broader rural development framework. The research aims to fill the gap between macro policy and the micro reality of an upland community on a self-declared ‘tipping point’.

Is research supporting sustainable management in a changing world? Insights from a Mediterranean silvopastoral system

Science-based sustainable management of agroforestry and silvopastoral systems is essential for their maintenance in a changing world. Using bibliometric and network analyses, we characterized how research is addressing the ecological and socio-economic dimensions of sustainable management of cork oak (Quercus suber) silvo pastoral systems, Mediterranean ecosystems of high nature conservation and socio-economic value. We retrieved publications on cork oak from the Web of Science. More than 60 countries contributed with research on this system. Retrieved papers addressed a great diversity of topics and were published in a variety of journals, highlighting the multidisciplinary character of cork oak research. Research grew exponentially after the 1990’s, possibly stimulated by the establishment of the European Forest Ecosystem Research Network. Our analysis shows that most research priorities identified for the Mediterranean region are being well addressed in cork oak systems, although research on the interactions between ecological and socio-economic components remains underrepresented. Less research has been published in North Africa compared to Europe, which is worrisome because it hosts a large area of cork oak that faces major sustainability challenges, often different from those prevailing in Europe. Our study shows that, despite constraints, the global scientific community is contributing to fill relevant knowledge gaps on the sustainability of cork oak systems across their range. Bibliographic and network analyses proved effective to uncover patterns, gaps, and potential constraints on cork oak scientific research and can be easily used to analyze research in other agroforestry and silvopastoral systems worldwide.

Impacts of using a precision livestock system targeted approach in mountain sheep flocks

Although mountain sheep systems suffer from climatic and environmental handicaps that constrain productivity and economic viability, they have an important economic role, maintain habitats and species of high nature conservation value and support the provision of a range of ecosystem services of benefit to society. Using Precision Livestock Farming (PLF) in extensive mountain sheep systems could bring benefits for animal performance, economical performance and labour. This paper presents results from a 3 year experiment where PLF principles were implemented on an extensive mountain sheep farm and an assessment made of whether or not such an approach could benefit more marginal sheep systems. A 900 ewe flock (600 Scottish Blackface ewes, 300 Lleyn ewes) was divided equally into two separate systems, one where the flock was managed conventionally (CON) at group level, and the other where the individuals in the flock were subjected to a PLF management protocol where electronic weighing, recording and drafting equipment were used, linked to the electronic identification (EID) tags of the animals. Two main management strategies were compared and contrasted; one relating to winter feeding of the pregnant ewes, the other relating to anthelmintic treatment of lambs during the summer. Yearly labour profiles were created by measuring the time spent doing individual tasks associated with the two management systems. Net margins (£/ewe) were calculated for the two systems. Additionally, the yearly labour profiles were scaled-up using commercial data to quantify potential labour savings on more traditionally managed mountain farms if PLF principles were adopted. Analyses indicated that the two different management systems did not result in any significant difference in terms of ewe weights, mid-pregnancy scanning figures, ewe and lamb mortality rates, or lamb weight post-weaning. However, the proportion of lambs needing anthelmintic treatment was significantly reduced by 40% between the CON and the PLF, resulting in a reduction of 46% in the amount of anthelmintic used. Over a whole year, the total amount of labour required in the PLF management system was reduced by 36%. Across the 3 years, the net margin for the two systems showed an average difference of £3/ewe higher in the PLF. For a more traditional farm embracing a PLF approach, analyses suggested labour reduction of 19%, equating to £1.60/ewe savings. This study shows that it is beneficial for farmers to consider managing a mountain ewe flock at an individual rather than at flock or batch level using PLF technology.

Revealing areas of high nature conservation importance in a seasonally dry tropical forest in Brazil: Combination of modelled plant diversity hot spots and threat patterns

The Caatinga biome has been identified as one of the important wilderness areas on earth. However, less than 1% of the region is under strictly legal protection although Seasonally Dry Tropical Forests (SDTFs) are globally highly endangered. There is an urgent need to increase the understanding of diversity pattern and threaten status of Caatinga plant species to preserve the unique biodiversity and protect endangered species. Species distribution modelling (SDM) can support strategic decisions in nature conservation for poorly researched tropical regions. This study provides the first highly representative, spatially explicit overview of plant diversity and threat status for the entire Caatinga, a semi-arid area in Northeast Brazil. For this purpose, we developed (a) a stacked species distribution modelling (S-SDM) approach to predict quantitatively floristic species richness and patterns of threatened plant species and (b) a combined approach of diversity hot spots and hubs of threatened species to derive conservation importance units (CIU) to contribute to improved nature reserve management. We applied the modelling technique MaxEnt to establish predictive distribution models with 22 uncorrelated predictors including climate, topography, solar radiation and soil information at a high spatial resolution of 30 arc-seconds (approx. 1km). Spatial patterns of species richness and threat status were derived by stacking 1062 plant species and 27 endangered species, respectively. These outputs were compared to two levels of protected areas (Brazilian and international standards) and intensive human land use patterns to define a set of recommendations for conservation management. Our complementary S-SDM approach showed that our predicted CIUs covered an area of 24% across the entire biome, whereas only 7% of the Caatinga is currently protected based on the Brazilian standards. We found that apart from an excellent overlap of 38% between CIUs and the current protected areas, a substantial proportion of CIUs (89%) was predicted outside the existing reserve network. Moreover, our findings enable targeted surveys to be done in order to enhance conservation efforts and ensure the efficient use of available resources in this poorly studied tropical region. Future upcoming local and regional studies could focus on a multi-taxonomic approach including e.g. insects, reptiles or mammals as a holistic perspective towards biodiversity conservation.

The impact of different cutting regimes on population density of Jacobaea aquatica (Hill) G. Gaertn., B. Mey. & Scherb. and grassland vegetation

Jacobaea aquatica is a monocarpic Asteraceae growing in wet grasslands of low management intensity. It is considered a noxious weed because it contains pyrrolizidine alkaloids, which cause health problems to livestock. The aim of this study was to develop management options to reduce the population density of J. aquatica in meadows of high nature conservation value without negative impacts on plant species diversity. The study site is located at the Hercynian part of Lower Austria near the city of Gmünd. The effect of five different cutting regimes on population density and seed production of J. aquatica as well as on species richness of the surrounding vegetation was tested on permanent plots from 2007 to 2012. One cut in October diminished J. aquatica but species richness decreased. Two cuts during the peak flowering period (July and August) and October reduced the population density of J. aquatica by c. 70% without obvious loss of species richness. Traditionally practiced two cuts in June and September lead to a rapid population growth of J. aquatica. According to our results, a first cut in June providing non-toxic fodder and two additional cuts during peak flowering are appropriate to reduce J. aquatica and to maintain biodiversity.

Patterns and drivers of scattered tree loss in agricultural landscapes: orchard meadows in Germany (1968-2009).

Scattered trees support high levels of farmland biodiversity and ecosystem services in agricultural landscapes, but they are threatened by agricultural intensification, urbanization, and land abandonment. This study aimed to map and quantify the decline of orchard meadows (scattered fruit trees of high nature conservation value) for a region in Southwestern Germany for the 1968 2009 period and to identify the driving forces of this decline. We derived orchard meadow loss from 1968 and 2009 aerial images and used a boosted regression trees modelling framework to assess the relative importance of 18 environmental, demographic, and socio-economic variables to test five alternative hypothesis explaining orchard meadow loss. We found that orchard meadow loss occurred in flatter areas, in areas where smaller plot sizes and fragmented orchard meadows prevailed, and in areas near settlements and infrastructure. The analysis did not confirm that orchard meadow loss was higher in areas where agricultural intensification was stronger and in areas of lower implementation levels of conservation policies. Our results demonstrated that the influential drivers of orchard meadow loss were those that reduce economic profitability and increase opportunity costs for orchards, providing incentives for converting orchard meadows to other, more profitable land uses. These insights could be taken up by local- and regional-level conservation policies to identify the sites of persistent orchard meadows in agricultural landscapes that would be prioritized in conservation efforts.

Impact of Climate on Vegetation Change in a Mountain Grassland – Succession and Fluctuation

Traditionally managed Central European mountain grasslands have high nature conservation value because of their high species diversity. Whether these grasslands and their diversity can be preserved will depend on many factors, including how plant species composition responds to changes in climate conditions. To differentiate between fluctuations and directional succession in the herbaceous layer composition of a Romanian Festuca rubra L. and Agrostis capillaris L. grassland in Apuseni and whether any compositional changes can be related to climate. The vegetation of permanent plots was recorded annually between 2004 and 2012. Temperature and precipitation were measured by an automatic weather station at the study site. Cluster analysis, Indicator Species Analysis and the co-dominance ratio between F. rubra L.- A. capillaris were analysed. The compositional data was related to the climate variables. Thresholds of relevant climate variables differentiating between clusters of plots with similar vegetation composition were determined using classification tree methods. The vegetation composition in our plots within the years 2004, 2005 and 2008 were different from each other. From 2004 to 2006 directional succession could be identified; however the major patterns to emerge were fluctuations which occurred over the whole study period. Compositional shifts included A. capillaris L. and F. rubra L exchanging co-dominance with each other. The most important variables differentiating clusters were temperature during the dormant and vegetation periods and water balance during the vegetation period. It can be concluded that compositional shifts among years were largely a consequence of year to year climatic fluctuations; however, there is some evidence for a directional shift during the early years of the study./span>

Impact of Climate on Vegetation Change in a Mountain Grassland – Succession and Fluctuation

Traditionally managed Central European mountain grasslands have high nature conservation value because of their high species diversity. Whether these grasslands and their diversity can be preserved will depend on many factors, including how plant species composition responds to changes in climate conditions. To differentiate between fluctuations and directional succession in the herbaceous layer composition of a Romanian Festuca rubra L. and Agrostis capillaris L. grassland in Apuseni and whether any compositional changes can be related to climate. The vegetation of permanent plots was recorded annually between 2004 and 2012. Temperature and precipitation were measured by an automatic weather station at the study site. Cluster analysis, Indicator Species Analysis and the co-dominance ratio between F. rubra L.- A. capillaris were analysed. The compositional data was related to the climate variables. Thresholds of relevant climate variables differentiating between clusters of plots with similar vegetation composition were determined using classification tree methods. The vegetation composition in our plots within the years 2004, 2005 and 2008 were different from each other. From 2004 to 2006 directional succession could be identified; however the major patterns to emerge were fluctuations which occurred over the whole study period. Compositional shifts included A. capillaris L. and F. rubra L exchanging co-dominance with each other. The most important variables differentiating clusters were temperature during the dormant and vegetation periods and water balance during the vegetation period. It can be concluded that compositional shifts among years were largely a consequence of year to year climatic fluctuations; however, there is some evidence for a directional shift during the early years of the study.

Alluvial grasslands along the northern upper Rhine – nature conservation value vs. agricultural value under non-intensive management

Semi-natural non-intensively managed grasslands are among the most species-rich and threatened ecosystems in Central Europe. Alluvial meadows along large European rivers are part of the European Union's Habitats Directive, and therefore part of conservation and restoration efforts. Sustainable management of these meadows should aim to reconcile the interests of both nature conservationists and farmers. In this context, we conducted a two-year comparative study in alluvial meadows of high and low nature conservation value, belonging to the alliances Arrhenatherion and Cnidion. Firstly, we aimed to assess how differences in fodder yield and quality are linked to abiotic and biotic factors. Secondly, we addressed the possibility of incorporating fodder from these meadows into livestock farming. Our results revealed that while yield tended to be higher in meadows of low nature conservation value, fodder quality (e.g. energy content) showed the reverse trend. These differences are most likely caused by differences in vegetation composition and soil fertility. In addition, the response seemed to be closely linked to the precipitation pattern. In 2006, when precipitation was evenly distributed, fodder quantity seemed to be mainly related to site conditions. In 2007, when a drought occurred in April, differences in the proportion of functional groups were additionally related to differences in yield. The degree to which this fodder can be integrated into farming systems depends on the intensity of livestock farming and marginal economic conditions. The present study confirms that under non-intensive management, meadows of high and low nature conservation value yield similar fodder qualities.

The relative importance of nitrogen deposition as a driver of Racomitrium heath species composition and richness across Europe

Nitrogen (N) deposition is a major global threat to biodiversity and ecosystem function. Increased deposition rates are linked to reduced species richness and vegetation change in a wide range of habitats. Here, we use gradients of N deposition and climate across thirty-six European sites to examine impacts of N deposition relative to those of climatic, soil and grazing conditions, on composition of Racomitrium heath, a moss-dominated mountain summit community of high nature conservation value. Nitrogen deposition was the second most important driver of community composition after climatic conditions at this European scale, explaining 15% of variability, and was more important than soil factors or current grazing. Along a gradient of 0.6–39.6kgNha−1y−1species richness declined by 5speciesm−2 and there was a 30% shift in cover from mosses to graminoids. Such large changes in dominant plant functional type have potential to impact on other biota and on habitat functions including nutrient cycling and hydrology. Importantly, changes in community composition were seen across the whole range of N deposition, with impacts on sensitive components such as lichens seen at rates of N deposition only slightly above background. No evidence was found for a threshold deposition rate or critical load below which no change in composition occurred. This study demonstrates the powerful role of N deposition as a driver of plant community change relative to other factors, and highlights the sensitivity of alpine habitats adapted to low background N deposition levels.

Species diversity and life history traits in calcareous grasslands vary along an urbanization gradient

Calcareous grasslands are among the most species-rich plant communities in Europe with a particularly high nature conservation value. During the past centuries their distribution has markedly decreased, at least partly due to urbanization. Thus we investigated the effects of urbanization on species diversity along a spatio-temporal urbanization gradient from traditionally managed grassland to areas affected by urban developments, which was situated in the plains northwest of Munich, Germany. Both a RLQ analysis linking species and environmental traits, and a redundancy analysis of the plant community features showed that soil disturbance, soil sealing and mean temperature explained most of the environmental variation along the gradient. The species in urban habitats showed increased insect pollination, earlier flowering and prolonged seed longevity. While urbanization favored short-lived species with dysochorous dispersal, the reference grasslands harbored more wind-pollinated perennials with effective vegetative spread and relatively large, short-lived seeds. Compared to the urban sites, traditionally used grasslands had a higher species diversity, more threatened species and a lower proportion of non-natives. We conclude that even under conservation management, urban habitats are not capable of maintaining the original biodiversity. However, we also found threatened species occurring exclusively in urban sites. Hence, urbanization decreased the area and diversity of traditional calcareous grasslands, but it also established niches for endangered species which are not adapted to the living conditions in calcareous grasslands.

On the Spatio-Temporal Approaches Towards Conservation of Extensively Managed Rural Landscapes in Central-Eastern Europe

Abstract Land-use change is one of the major drivers of global biodiversity loss, its study experiencing continuous development and increasing recognition, influencing main research directions within ecology. Many studies target the negative aspect; however, the modification of the natural environment over centuries and millennia led to the biodiversity, in its broadest sense, we are trying to conserve nowadays within cultural landscapes. This theoretical paper deals with the issue of spatial and temporal variations in extensively managed rural landscapes from Central-Eastern Europe. The constraints of the state of the art and arising challenges for biodiversity management in complex, farmed landscapes of high nature conservation value are discussed, through the example of Transylvania (Romania). The paper argues for the necessity of considering historical perspectives and traditional knowledge in an attempt to understand the current on-site conditions and developing realistic adaptive management strategies with special emphasis on the (traditional) rural communities, representing a key resource for biodiversity conservation

Tunisian man‐made wetlands as alternative habitats for waterbirds and their role for conservation

AbstractThe distribution of wintering waterbirds within some Tunisian artificial wetlands (AW) was studied during the 2004–2007 stable wintering periods. The survey has regarded 88 wetlands including 27 large dams, 25 hill dams and 36 hill lakes. We identified 42,840 individuals representing seven orders, eleven families, 37 species and six functional groups: dabbling ducks, grazing waterfowl, fish‐eaters, deep‐water foragers, shoreline foragers and waders. The population structure analysis showed an absolute dominance of the deep‐water foragers with approximately 82% of observed waterbirds. The total abundance survey showed a fluctuation of population sizes and richness, from thousands to few individuals and from 1 to 25 species, respectively. Analysis results showed that the species distribution is governed by several ecological factors and there was a significant correlation between species abundance and richness and some habitat variables such as area, depth, age, plant cover and hunting disturbance. Investigated AW revealed a significant carrying capacity and refuge serving for the conservation of numerous wintering and endangered waterbird species of high nature conservation value, the White‐headed Duck Oxyura leucocephala that has been observed with relatively high numbers representing more than 40% of the assessed Tunisian–Algerian population.

What determines Orthoptera species distribution and richness in temperate semi-natural dry grassland remnants?

Wide-spread fragmentation and isolation of habitats with high nature conservation value lends increasing importance to a better understanding of the factors which determine species richness in isolated habitat patches. Using data of one of the most abundant invertebrate groups in grasslands, Orthoptera, we analysed how species richness and distribution in 60 isolated semi-natural grassland remnants in Austria were affected by five environmental variables (altitude, habitat and land use diversity within each patch, habitat diversity of areas adjacent to each patch, patch size), and related to diversity of their main food source, i.e. vascular plants. We found a significant positive correlation between Orthoptera and vascular plant species richness, with threatened Orthoptera species having the lowest correlation coefficients. Life form diversity of plants was only moderately positively correlated with Orthoptera species richness. Habitat diversity within and adjacent to the grassland patch had by far the highest loadings on the first two axes of the principal component analysis, which jointly explained 99 % of the variance, and proved to be significant for total, threatened and not threatened Orthoptera, as well as for the two Orthoptera orders occurring in Central Europe (Caelifera, Ensifera). Additionally, the distribution of the majority of those 14 Orthoptera species analysed individually was mainly correlated with habitat diversity within and adjacent to the grassland patch. However, the distribution of a significant proportion of species was associated with other factors: five species were closely related to on-site land use diversity and patch size, and the distribution of three Ensifera species was not significantly correlated to any of the explanatory variables. We conclude that a surrogate taxa approach, i.e. the use of well-known taxonomic groups (e.g. vascular plants), may indeed deliver good results for capturing total, but less so for threatened, Orthoptera species richness in semi-natural grassland remnants. Small scale habitat diversity may be crucial to allow for the co-existence of a large number of Orthoptera species and has to be taken equally into account as patch size in nature conservation.

Integrating climate change into calcareous grassland management

Summary1. Climate change is rarely taken into consideration in conservation management strategies aimed at protecting biodiversity from other threats. We examined the implications of this perspective in European calcareous grasslands, which are among the richest herbaceous systems of the continent and are therefore of high nature conservation interest. These systems are currently undergoing species loss because of the abandonment of agro‐pastoral practices. Classic ecological theory assumes that conservation management activities (such as regular mowing) and drought events should increase diversity through decreased plant competition in abandoned mesic communities. In turn, this could reduce diversity in xeric communities although positive plant interactions (facilitation) might buffer these negative effects and maintain diversity.2. We studied the effects of regular mowing and experimentally induced drought on diversity and biotic interactions between two transplanted species in mesic and xeric calcareous grasslands. The study sites in south‐western France have not been subjected to any management for the last 30 years.3. Drought did not affect mesic systems although mowing increased plant diversity through decreased competition. By contrast, mowing had no significant effect in xeric systems although drought decreased diversity. Interestingly, transplants were subject to neither competition nor facilitation in the xeric systems.4. Synthesis and applications. Regular mowing and drought events impact plant diversity of mesic and xeric calcareous grassland communities in different ways. We recommend regular mowing of mesic grasslands, even in the context of climate change. By contrast, we recommend less‐frequent mowing of xeric grasslands together with specific interventions such as assisted migration for species with poor drought tolerance. Similar studies in other ecosystems on larger spatial and temporal scales should examine the dual effects of management and climate change to identify appropriate management programmes.

Changes in the vegetation composition of hay meadows between 1993 and 2009 in the Picos de Europa and implications for nature conservation

The Picos de Europa are a range of predominantly Carboniferous Limestone and Sandstone mountains mainly in the Cantabrian region of northern Spain. The highest peaks are precipitous and reach 2600m. There are complex gradients between Lusitanian, Alpine and Mediterranean environmental zones, as well as variable soil types. In combination with the long history of traditional agricultural management, a wide range of diverse habitats and species is present. The herb-rich hay meadows have long been recognised as having a high nature conservation value but, as elsewhere in European mountains, such grasslands are threatened by changing agricultural practices. Accordingly, in 1993, 92 quadrats were recorded using a restricted list of indicator species from stratified random samples. The authors repeated the sample in 2009. Changed land use had only occurred in approximately 3% of meadows, however, farmyard manure was no longer used, probably because of shortage of labour. Statistical analysis of the vegetation data showed a range of significant changes consistent with the increased use of slurry, as well as re-seeding of some fields. The grass swards had not only become denser, with fewer species present, but there was also a loss of sensitive indicators especially of calcareous conditions and open vegetation. By contrast, competitors had increased and the vegetation had become simpler, with the balance of vegetation types shifting to more nutrient rich conditions. These changes have mainly occurred in the more fertile meadows used for silage. The core of about 35% of herb-rich meadows, mainly cut for hay, has remained relatively stable but the results show that they are at risk if the current trend continues. If management practices that form the core of traditional agriculture are not maintained, one of the most important resources of herb-rich meadows in Europe will be lost.

Assessing long-term land-use legacies in subalpine grasslands by using a plant trait-based generic modelling framework

Background: In European mountains, where semi-natural grasslands have high cultural and nature conservation value, land-use legacies from past ploughing are associated with distinct floristic compositions and ecosystem properties. It remains unknown if these differences are stable or if post-arable grasslands are only transient states that eventually follow a predictable successional pathway. Aims: We use a generic vegetation dynamics model based on plant traits to test these alternative hypotheses in subalpine grasslands of the central French Alps. Methods: We classified dominant graminoids into trait-based Plant Functional Types (PFTs) and simulated their long-term response to fertility, annual mowing and past ploughing. Results: Simulations demonstrated that a temporary dispersal limitation of long-lived tussock grasses could have allowed species-rich hay meadows to develop as alternative communities. We also show that when they are regularly mown, meadows are resistant to colonisation by long-lived tussock grasses. Conclusions: Our results thus support traditional management based on regular mowing, but also highlight the key role of landscape history through its effects on dispersal. Our study also demonstrates the usefulness of easy-to-measure plant traits and a widely applicable generic modelling framework for testing hypotheses on the long-term interactions of multiple drivers of vegetation dynamics.

Ashtead Common, the evolution of a cultural landscape: A spatially precise vegetation record for the last 2000 years from southeast England

The results of palaeoecological (pollen and fungal spores) investigations of an abandoned clay pit on Ashtead Common, Surrey are presented and compared with archaeological and documentary evidence. The pit lies adjacent to a Roman industrial complex, with early Saxon activity recorded nearby. Prior to the early twentieth century AD the Common was managed as wood-pasture and it has a high nature conservation designation as a result of c. 2000 veteran pollarded oak trees which remain from this phase. The pit provides a record of landscape history from the Roman ( c. cal. AD 150) to the modern ( c. AD 1850) era which, in terms of spatial and temporal resolution, is unrivalled in southeast England. From the late Roman into the middle Saxon period the palaeoecological data are consistent with archaeological evidence for the continuity of settlement and land use. Subtle changes in woodland cover, probably reflecting changes in the importance of grazing against the exploitation of wood, are evident up to c. cal. AD 1200. Thereafter grazing pressure on the Common appears to have increased and the resulting shortage of underwood is likely to have led eventually (cal. AD 1490—1680) to the adoption of pollarding. Changes in depositional environment are shown to have a major impact on the fungal spore record. In general terms the stratigraphic data from the Ashtead Common pit accord well with archaeological/documentary evidence and demonstrate the utility of studies which use a combination of sources to reconstruct vegetation change in the historic era.

Restorative removal of plant litter and vegetation 40 years after abandonment enhances re-emergence of steppe grassland vegetation

The accumulation of biomass and of dead plant remains is a direct consequence of grassland abandonment. Litter can occupy potential microsites for seed germination and seedling establishment, and thus decrease species diversity in the long-term. This effect can be more accentuated in dry grassland of open structure where species are adapted to excessive light and bare surfaces during the recruitment phase. We conducted a field experiment with litter removal alone or in combination with vegetation cutting and studied germination and seedling survival during 2 years in two abandoned steppe sites. With our experimental treatments we intended to create microsites and to activate the seed bank, with the aim to enhance recruitment of dry-grassland species; potentially also those already absent from the established vegetation. Our results show, that while both treatments significantly increased recruitment by enhancing seed germination in the first year of the study, only litter removal combined with vegetation cutting significantly promoted seedling survival during both years. Our experiment demonstrated that even after 40 years of abandonment the applied measures favoured the re-emergence of target species that were very rare or absent from the above-ground vegetation of continental steppe-like grassland. Thus, management prescriptions which comprise removal of dead and even living biomass, such as mowing or grazing, are considered beneficial for this habitat type of high nature conservation priority.