•We investigated the importance of small habitat elements for grassland plant diversity.•Smallest share of specialists was found in small habitats in modern agricultural landscapes.•β-Diversity was ...highest in the most intensively managed agricultural landscape.•Species richness declined with distance to grasslands in modern landscapes.•Small habitats provide an important function for plant richness at a landscape scale.
The extensive transformation of agricultural landscapes worldwide has led to a decrease in grassland species related to traditional low-intensive farming. To properly manage and protect species, habitats and ecosystems in any of these landscapes requires a better understanding of direct and indirect effects of the processes driving biodiversity decline. In this study, we investigated how small habitat elements, represented by mid-field islets and road verges, in different types of agricultural landscapes can sustain a regional species pool for plant diversity otherwise associated to semi-natural grasslands. Although semi-natural grasslands had higher total and specialist richness, we found that small habitat elements harboured relatively high plant species richness, especially in a landscape with many semi-natural grasslands left. In the most intensively managed landscape, total richness declined as distance to the nearest semi-natural grassland increased. In contrast, β-diversity was highest in these landscapes indicating that small habitats are also negatively affected by distance to grassland. We found that species trait composition varied depending on habitat and landscape. The results confirm that fragmentation shape trait composition within plant communities, e.g. plant size, clonality, longevity, and dispersal traits. We conclude that small habitat elements increase the total area available to grassland species present in the landscape, boosting the spatio-temporal dynamics of grassland communities. Small habitat elements may hence function as refugia or stepping stone habitats, especially in intensively utilized agricultural landscapes, and should be regarded as a functional part of a semi-natural grassland network, analogous to a meta-population.
Small marginal habitats in the rural landscape may play an important role for plant species richness as refugias. Little is known how the surrounding landscape and landscape history influence these ...patterns. I analysed how plant species richness was affected by isolation, habitat area, past and present land use, and if landscape context matters. Plant species occurrence in two different types of small marginal habitats were analysed, road verges and midfield islets. The study was conducted in two different agricultural landscapes in Sweden; one open modern agricultural landscape and one traditional rural landscape, and the results compared. Present and past land use, and landscape change was analysed using aerial photographs and old maps. There was a large grassland reduction more than 50 years ago in the modern landscape, when there still were quite a lot of grasslands left in the traditional landscape. Area and connectivity were more important for plant incidence in small remnant habitats in the modern landscape, compared to the less fragmented, traditional rural landscape. On the other hand there were more grassland specialists, 23% in the traditional landscape compared to 16%. Species richness became higher on midfield islet if grazing was re-introduced. The legacy of surrounding landscape remains in the species pool for a long time, atleast 50 years, even in small grassland fragments. Although small grassland remnants are more sensitive to fragmentation effects compared to larger grasslands, they still encompass a substantial part of the grassland species pool and may be valuable for reconstructing grassland management at a landscape scale.
Past semi-natural grassland extent is thought to have a major influence on contemporary species richness in rural landscapes. The loss of grasslands over the last 300
years was reconstructed for 12 ...rural landscapes in Sweden, ranging from open modern agricultural landscapes to more forested landscapes. Old maps and aerial photographs from 1950s and today were used to reconstruct landscape patterns in four time-steps to investigate how present plant species richness relates to past grassland extent and decline in old and new grassland habitats. The relative importance of soil properties on the timing of grassland decline was assessed. Plant species occurrence was recorded in managed and abandoned grassland habitats in each landscape.
Past and present grassland distribution was a major factor in determining plant species patterns found in grasslands today. All landscapes had an average of 80% grassland 300
years ago. Since then grassland has declined by 90% across all landscapes. Proportion of clay soils influenced the timing of grassland decline, where grasslands in landscapes dominated by clay soils were conversed to crop-fields more than 100
years ago. Grasslands on coarser soils declined later, primarily to forest. Landscapes with more than 10% semi-natural grassland left today had 50% higher species richness in all grasslands, including both abandoned and new grassland. Time since major grassland decline also seems to have an effect on the landscapes’ species richness. The results show that plant species patterns in grasslands at local scales are determined by broader landscape processes which may have occurred many centuries ago.
Persistent seed banks are a key plant regeneration strategy, buffering environmental variation to allow population and species persistence. Understanding seed bank functioning within herb layer ...dynamics is therefore important. However, rather than assessing emergence from the seed bank in herb layer gaps, most studies evaluate the seed bank functioning via a greenhouse census. We hypothesise that greenhouse data may not reflect seed bank-driven emergence in disturbance gaps due to methodological differences. Failure in detecting (specialist) species may then introduce methodological bias into the ecological interpretation of seed bank functions using greenhouse data. The persistent seed bank was surveyed in 40 semi-natural grassland plots across a fragmented landscape, quantifying seedling emergence in both the greenhouse and in disturbance gaps. Given the suspected interpretational bias, we tested whether each census uncovers similar seed bank responses to fragmentation. Seed bank characteristics were similar between censuses. Census type affected seed bank composition, with >25% of species retrieved better by either census type, dependent on functional traits including seed longevity, production and size. Habitat specialists emerged more in disturbance gaps than in the greenhouse, while the opposite was true for ruderal species. Both censuses uncovered fragmentation-induced seed bank patterns. Low surface area sampling, larger depth of sampling and germination conditions cause underrepresentation of the habitat-specialised part of the persistent seed bank flora during greenhouse censuses. Methodological bias introduced in the recorded seed bank data may consequently have significant implications for the ecological interpretation of seed bank community functions based on greenhouse data.
Current agri-environmental schemes and subsidies for conservation and restoration of semi-natural grasslands do not explicitly assess land use changes affecting whole landscapes, but have so far ...focused on single objects and small areas. In this paper, we discuss a landscape perspective versus a “single object” perspective when conserving semi-natural grassland in agricultural landscapes. The focus is on the values biodiversity, cultural heritage, a vital countryside, and effects on economy when land use changes. We conclude that when land use change in the landscape surrounding an object, important additional effects on the different values are found. For example, a countryside where animals graze former arable fields and where marginal habitats are managed will have a positive effect, not only on the biodiversity associated to semi-natural grasslands, but also for the image of a vital and dynamic landscape. An increased number of roads, on the other hand, may negatively affect cultural heritage and decrease biodiversity in grasslands, leading to negative effects on the value of common goods through isolation. Placing objects in a larger spatial context and combining several different aspects into a landscape perspective, will improve long-term preservation of values associated to semi-natural grasslands.
Lately there has been a shift in Sweden from grazing species-rich semi-natural grasslands towards grazing ex-arable fields in the modern agricultural landscape. These fields normally contain a ...fraction of the plant species richness compared to semi-natural grasslands. However, small remnant habitats have been suggested as important for plant species diversity and conservation as they may function as refugia for grassland specialists in fragmented and highly modified agricultural landscapes. In this study, we examined whether plant communities on small remnant habitats, i.e. midfield islets, can function as sources for grassland species to disperse out into surrounding grazed ex-fields (former arable fields). We examined species richness and grassland specialists (species favoured by grazing) and their ability to colonize fields after 5 and 11 years of grazing. The fields that had been grazed for a shorter time were fairly species-poor with few grassland specialists. A longer period of grazing had a positive effect on total and small-scale species diversity in both islets and fields. Species composition became more similar with time, and the number of grassland specialists in both habitats increased. We found that grassland specialists dispersed step-wise into the fields, and the number of grassland specialists decreased with distance from the source. Our study suggests that remnant habitats, such as midfield islets, do function as a source community for grassland specialists and enhance diversification of grassland species when grazing is introduced. For long-term conservation of plant species, incorporating small refugia into larger grazing complexes may thus enhance species richness.
Plants associated with traditional agricultural landscapes in northern Europe and Scandinavia are subjected to drastic habitat fragmentation. In this paper we discuss species response to ...fragmentation, against a background of vegetation and land-use history. Recent evidence suggests that grassland-forest mosaics have been prevalent long before the onset of human agriculture. We suggest that the creation of infield meadows and outland grazing (during the Iron Age) increased the amount and spatial predictability of grasslands, resulting in plant communities with exceptionally high species densities. Thus, distribution of plant species in the present-day landscape reflects historical land-use. This holds also when traditional management has ceased, due to a slow response by many species to abandonment and fragmentation. The distribution patterns are thus not in equilibrium with the present habitat distribution. Fragmentation influences remaining semi-natural grasslands such that species density is likely to decline as a result of local extinctions and invasion by habitat generalists. However, species that for a long time have been subjected to changing mosaic landscapes may be more resistant to fragmentation than is usually believed. Conservation should focus not only on ‘hot-spots’ with high species richness, but also consider species dynamics in a landscape context.
The importance of the landscape surrounding a protected area for sustaining its values is frequently discussed in conservation literature. Studies on the interactions of urbanisation and nature ...conservation at the global scale suggest that protected nature attracts urbanisation, and that this in turn might negatively impact the area. However, studies specifically addressing such land use dynamics at city scale are largely missing. In this study we examine the change in proportion of built up area in two zones (500 m and 1000 m) surrounding 15 urban nature reserves in southern Sweden. By using comprehensive maps from the last 50 years, we compared the zones to the overall urbanisation in the cities to reveal discrepancies in land use surrounding the nature reserves. We found that the amount of built up area in the buffer zones surrounding nature reserves followed the same trend as the corresponding cities and this relation was stable over time, although the positive relationship was not significant. The establishment of nature reserves had no detectable effect on surrounding land use, however two distinguished groups of reserves were identified with either more or less built up area in buffers zones compared to cities. These differences were related to specific local drivers such as land ownership, land use history and nature reserve location. In contrast to earlier studies at global scale, our study did not show that nature reserves attract urbanisation. Instead, we stress that the great variety of contextual factors at the city scale makes quantitative analysis of this kind extremely difficult. However, a general neglect from planning and nature conservation agencies to recognise nature reserves’ dependence on the surrounding landscape configuration could be detrimental to sustain their values in the long-term. Hence we suggest that zones surrounding nature-protected areas should be planned and managed according to local land use history and current landscape conditions to enable and enhance necessary cross-boundary interactions.
► Landscape scale study of nature conservation and urbanisation dynamics. ► Analysing 50 years of land use changes around 15 nature reserves in Swedish cities. ► Did not prove any increase in urbanisation related to nature reserves establishment. ► Land use history and threats of exploitation seemed to have a larger impact. ► Neglect of landscapes’ social and ecological interactions risks nature conservation.
This paper explores the possibility of using non-geometric cadastral maps from the 17th and 18th century together with aerial photographs from 1945 and 1981 to analyse land-cover change in south-east ...Sweden. Habitats rich in plant species in the European rural landscape seem to be correlated with a long continuity of management. Accurate spatial data from historical data sources are fundamental to understand patterns of vegetation and biodiversity in the present-day landscape. However, traditional methods for rectification of non-geometric maps using corresponding points from orthophotos or modern maps are not satisfying, as internal inaccuracies will remain in the maps. This study presents a method to rectify the maps by local warping, thereby eliminating geometrical irregularities. Further, the land-cover changes were calculated and presented as transition matrices. The extent of arable fields and grasslands were analysed in relation to soil characteristics and continuity of management. The results show a dynamic relation between grassland and arable field, albeit the overall proportions remained almost the same between 17th and 18th centuries: 60% grassland to 32% arable field. The most substantial changes in land-cover were prior to 1945. Today there is 18% grasslands left in the study area, while 56% of the land-cover is arable field. Approximately 8% of present-day land-cover is semi-natural grassland 300 years of age or more. Compared to 300 years ago there is only 1% grassland left on peat and 2% on clay. In contrast, grassland covers associated with bare bedrock have been fairly stable in size. All semi-natural grasslands with a long continuity of management were situated on shallow soils, less than 50 cm depth. The major conclusions from this study are that (i) correctly rectified, old maps are very useful to address questions of land-cover changes in historical time, (ii) general trends in land use over 300 years in this hemi-boreal landscape seem to underestimate the full dynamics of land use change, and (iii) only a small proportion of the semi-natural grassland area had a 300 year continuity of management.
Over the past 100 years species-rich semi-natural grasslands have decreased dramatically in Western Europe, where former arable fields (ex-fields) are used instead as pasture. The disappearance of ...semi-natural grasslands has caused a threat to the biodiversity in agricultural landscapes. Many typical grassland plants are dispersal limited, thus grazed ex-fields can be used to investigate if species spontaneously colonise these new grassland habitats. We examined the relationship between surrounding landscape, field area, shape, distance between edge and centre, and plant species diversity in ex-fields that had been grazed for 15–18 years. The results showed that there were 35% more plant species in fields surrounded by commercial forestry production compared to those surrounded by open agricultural landscape. Area and shape did not influence species richness, although there was increasing number of species in the centre with decreasing distance from the edge. Twenty-five percent of the species where typical grassland species, and ex-fields surrounded by forest had 91% more grassland species compared to those in the open landscape. It is possible to increase grassland plant occurrences by grazing ex-fields surrounded by forest or other grassland remnant habitats, particularly in landscapes where grazed semi-natural grasslands are scarce.
