Maintaining an open landscape: Comparison of management methods for semi-natural grasslands: A Swedish multi-site study

Traditional management of semi-natural grasslands by grazing or annual mowing is not always feasible and the current study set out to evaluate alternative management methods. At eleven locations in southern Sweden, block experiments were conducted evaluating seven treatments in 5 m*20 m plots: grazing, annual mowing, annual spring burning, mowing every third year, mechanical removal of woody plants, herbicide control of woody plants, and untreated control. After approximately 13 years, trends for woody plants and species richness, and the occurrence of management-dependent plant species, low-grown species, and pollinator-attracting plant species were analysed. Overall, the annual mowing and grazing treatments resulted in fewer woody plants, the highest species richness, and more management-dependent, low-grown, and pollinator-attracting species. The untreated control plots showed the opposite effect, whereas less intense management (annual burning, mowing every third year, and mechanical and chemical treatments of woody plants) showed mixed and often intermediate effects. Compared to grazing and mowing, less intense management methods do not constitute long-term management alter-natives to preserve typical features of species-rich grasslands. However, they may be short-term alternatives at sites where the recruitment of woody species is absent or rare. However, to prevent the encroachment of woody species, less intensive management might be a better long-term alternative at more productive sites with slow or inhibited woody species recruitment

The usefulness of surrogates in biodiversity conservation: a synthesis.

Preserving biodiversity requires extensive information on species distributions and effectiveness of conservation actions. A surrogate approach, where a small number of species act as surrogates for broader groups of species, can simplify this task. Types of surrogates include indicator, umbrella, keystone and flagship species, and using diversity of higher taxonomic levels to represent species diversity. An overview of the empirical evidence of the usefulness of surrogates as a conservation tool is missing. We synthesised knowledge on if and when surrogate species are useful by systematically searching for meta-analyses and literature reviews assessing this. Results from 34 reviews revealed weak correlations between diversity of indicator species and other species and that umbrella species were not consistently useful for prioritising conservation actions. However, diversity of higher taxonomic levels can be representative of species diversity. No reviews have assessed the usefulness of keystone or flagship species. Thus, surrogate taxa often do not represent biodiversity or threatened species, and conservation actions aimed at surrogates might not necessarily benefit other species. However, surrogates are more likely to be useful when using a higher-taxon approach, when strong ecological similarities exists between a surrogate and other species, when surrogates are used at regional or landscape rather than local scales, and when using sets of multiple species as surrogates. As some use of surrogate species will always be necessary, surrogates should be carefully selected and their usefulness and cost-effectiveness should be assessed, including the risk that conservation actions aimed at that surrogate have unintended effects on other species

Constitutional Existence Conditions and Judicial Review

Although critics of judicial review sometimes call for making the entire Constitution nonjusticiable, many familiar norms of constitutional law state what we call existence conditions that are necessarily enforced by judicial actors charged with the responsibility of applying, and thus as a preliminary step, identifying, propositions of sub-constitutional law such as statutes. Article I, Section 7, which sets forth the procedures by which a bill becomes a law, is an example: a putative law that did not go through the Article I, Section 7 process and does not satisfy an alternative test for legal validity (such as the treaty-making provision of Article II, Section 2), has no legal existence. A judge who disclaims the power of judicial review nevertheless enforces Article I, Section 7 when he finds that a putative statute is (or is not) an enactment of Congress that he must take account of. We contrast existence conditions with application conditions that limit the legal force of a proposition of nonconstitutional law by some means other than vitiating the status of that proposition as law. For example, absent payment of just compensation, the Takings Clause would block the application of an otherwise valid statute such as the Endangered Species Act to a privately owned parcel of land if the impact of that application were to destroy all economically viable use of the parcel. Judicial enforcement of application conditions is not entailed by the enforcement of ordinary sub-constitutional law, even though judicial non-enforcement of application conditions might be unwise. After setting forth the conceptual distinction between existence and application conditions, we argue that many familiar constitutional provisions and doctrines - including the scope of enumerated powers and some individual rights - are best read as existence conditions and are thus necessarily judicially enforced. We then reconcile that observation with a variety of doctrines - including the political question doctrine, the enrolled bill doctrine, and the rational basis test - that seem to authorize the courts not to enforce or to under-enforce existence conditions. We argue that these doctrines should be understood in some instances as granting epistemic deference to non-judicial interpreters of the Constitution and in other instances as reflecting the fact that some constitutional provisions and doctrines are perspectival - that is, they have different content for different addressees

The effects of urbanization, bark fissure depth and sun exposure on lichens in south eastern Sweden

Studies have shown that air pollution, as well as bark fissure depth and sun exposure of a tree can have an effect on lichen growth as well as abundance of lichen species. The aim of this study was to find out the relative importance of these factors. 211 oaks in south eastern Sweden were surveyed for presence of 17 lichen species, as well as the total number of lichen species. Half of the trees were situated in urban areas and half in the countryside. For each tree the bark fissure depth was measured and the sun exposure of the trunk was estimated. The results showed a significant negative effect on a majority of lichens growing in an urban environment and a significant positive effect on a majority of lichens growing on trees with deep bark fissures. The sun exposure was a less important factor but could not be excluded as a factor affecting lichen occurrence. These results show the negative effect urbanization can have on rare lichen species, as well as be used in the development and maintenance for the nature reserves containing the

Management of semi-natural grassland vegetation : long-term effects of grazing, mowing and different mowing techniques

Semi-natural grasslands are species-rich and one of the most threatened habitats in Europe, since land-use changes have led to reduced area of grassland. Appropriate management practices like grazing or mowing is needed to maintain the conservation values and species-richness of semi-natural grasslands. However, few studies have investigated which of grazing or mowing is most appropriate. Furthermore, almost no studies have investigated which mowing technique is best for the conservation value of grassland flora. The aim of this study was to determine which management practice of grazing and mowing, and which mowing technique, has the most positive effect on grassland flora. Data from two long-term trials were evaluated: one compared the effect of grazing and mowing in eleven sites in southern Sweden during at least twelve years; the other compared the effect of the knife mower and grass trimmer at different cutting heights in one site during twelve years. Meta-analysis was used, based on the odds for a plant record being an indicator species, using eight different indicator systems of classification of grassland plants. Over time, results show increasing odds of finding indicators of good management and no change in odds of finding indicators of lack of management in mowed compared to grazed plots. There were no differences in the odds of finding any indicator species for any of the mowing techniques. Hence, to maintain the conservation values of semi-natural grasslands, mowing is the better management practice compared to grazing. Mowing using a knife mower or grass trimmer has similar effects, and can both be recommended

Conservation of semi-natural grasslands : Effects of different management methods on biodiversity

Species-rich semi-natural grassland are valuable habitats in the agricultural landscape as they may contain a high diversity of both plant and animal species, as well as provide essential ecosystem services like pollination. To keep these habitats open and to maintain the biodiversity in them, management like grazing or mowing is necessary. Due to changed agricultural practices many semi-natural grasslands have been lost, e.g. due to secondary succession after abandonment or use of more intense management practices. As limited resources are available for the management and restoration of semi-natural grasslands, research is needed to find the best available management method that maintains biodiversity at a low cost. Therefore, the overall aim of this thesis was to use existing data to compare effects of different management methods and explore their effect on the biodiversity of semi-natural grasslands. More specifically, effects of grazing vs. mowing, different mowing frequencies and different mowing techniques were investigated using data from Swedish, European and global studies, with the aim of using the results to formulate management recommendations. Paper I investigated the effect of mowing using a sickle bar mower or a grass trimmer at a 5-cm or 0-cm cutting height on plant indicator species of good management for species richness, poor management and excess nitrogen. Analyses of data from a Swedish 11-year field experiment revealed that over time, there was no difference in the odds of finding indicators of any type for any of the mowing techniques. This suggest that there is a similar effect of mowing using a sickle bar mower and a grass trimmer on the floristic composition of semi-natural grasslands. Paper II and III investigated effects of different management methods using a Swedish long-term, multi-site field experiment. Paper II compared effects of grazing vs. mowing and paper III compared effects of annual mowing and mowing every third year. Both papers used meta-analyses to compare effect on plant indicator species of good management for species richness and poor management. Additionally, paper II examined effects of indicators of excess nitrogen, while paper III also examined effects on plant species richness and diversity and species-wise responses. For paper II, analyses revealed an increase in the odds of finding indicators of good management for species richness in mowed plots and increased odds of finding indicators of excess nitrogen in grazed plots. For paper III, meta-analyses revealed a small drop in plant species richness and diversity, and an increase in woody and tall-grown species, when mowing every third year. However, there were no difference in the odds of finding indicators of good management for species richness or poor management between mowing frequencies. These results suggest that mowing is a better long-term management method compared to grazing in seminatural grasslands in southern Sweden, while annual mowing have a slightly more positive effect compared to mowing every third year. Paper IV and V investigated management effects on a larger scale, by systematically reviewing studies comparing effects of grazing vs. mowing or different mowing frequencies on grassland flora and fauna, and analysing the data using meta-analysis. The included mowing frequencies were annual mowing vs. mowing every fifth, third or second year, or mowing two, three or four times a year. Paper IV analysed data from 35 studies from across the globe, and revealed a slightly more positive effect of grazing on the biodiversity of seminatural grasslands. However, results differed for different grassland characteristics like e.g. geography, grassland type and previous management. Paper V analysed data from 29 European studies, and revealed a more positive effect of mowing more frequently than once per year. However, the differences were small and varied for different grassland characteristics. For example, a higher mowing frequency was better in more productive grasslands. These results suggest that grazing is slightly better than mowing and that mowing less frequently, e.g. every other year, can be a viable management method in less productive grasslands, as a way of using limited funds more efficiently. The results from the papers included in this thesis suggest that different management methods have different effects on the biodiversity of semi-natural grasslands. However, in many cases these differences are relatively small. Thus, to a certain extent one of the most important factors for semi-natural grassland biodiversity seems to be the fact that management occurs at all, while the actual management methods is of less importance. Hence, choosing the most suitable management method for a certain situation should be based on conservation aims, grassland conditions, the previous management practice used, the cost of management, the availability of different management methods and previous research. Näringsfattiga ängs- och hagmarker är en viktig del av jordbrukslandskapet, då de ofta innehåller en hög artrikedom av både växt- och djurarter, samtidigt som de bidrar till upprätthållandet av viktiga ekosystemtjänster som exempelvis pollinering. För att bevara diversiteten i dessa habitat är det viktigt att de sköts på rätt sätt, via exempelvis bete eller slåtter, eftersom dessa skötselmetoder motverkar igenväxning av gräsmarker, samtidigt som de bibehåller de näringsfattiga förhållandena genom avlägsnandet av biomassa. På grund av intensifierade jordbruksmetoder har många artrika ängs- och hagmarker gått förlorade. Detta beror bland annat på att skötsel upphört på grund av för låg avkastning, eller en ökad användning av gödsling som förändrat förhållandena i gräsmarkerna. Med anledning av detta har många av de arter som är bundna till denna habitattyp blivit mer ovanliga och hotade. Begränsade resurser är tillgängliga för skötsel och restaurering av ängs- och hagmarker och därför behövs forskning som undersöker effekten av olika skötselmetoder, för att hitta de som har mest positiv effekt till en så låg kostnad som möjligt. Det övergripande målet med denna avhandling var därför att undersöka effekten av olika skötselmetoder på diversiteten i ängs- och hagmarker, för att ta fram passande skötselrekommendationer. Slåtter med verktyg som gräsröjare, som sliter sönder vegetationen, har länge ansetts ha en negativ effekt i jämförelse med skärande verktyg som exempelvis lie eller slåtterbalk, men få studier har undersökt detta. I artikel I undersöktes därför effekten av olika slåttermetoder på växter, i en ängsmark i södra Sverige. De undersökta metoderna var slåtter med slåtterbalk och slåtter med gräsröjare på två olika klipphöjder (o eller 5 cm). Effekterna undersöktes på indikatorarter för god hävd, brist på hävd och överskott av kväve. Resultaten visade att oddsen för att hitta de olika indikatorarterna inte skiljde sig mellan slåttermetoderna, vilket tyder på att de har en liknande effekt på vegetationen i ängsmarker. Artikel II jämförde effekten av bete och slåtter och artikel III effekten av slåtter en gång per år och slåtter vart tredje år. Bägge artiklarna använde sig av data från ett långtidsexperiment som utfördes i elva olika gräsmarker i södra Sverige, och jämförde skötseleffekter på växtindikatorarter för god hävd och brist på hävd. Artikel II undersökte även effekten på indikatorarter för överskott av kväve medan artikel III även tittade på effekter på artrikedom och diversitet, samt effekter på individuella arter. I artikel II visade analyserna att oddsen att hitta indikatorer för god hävd ökade med slåtter medan oddsen att hitta indikatorer för överskott av kväve ökade med bete. Analyserna i artikel III visade på en liten minskning av artrikedomen och diversiteten samt en ökning av vedarter och högväxta arter vid slåtter vart tredje år. Det fanns dock ingen skillnad i oddsen att hitta indikatorarter för god hävd eller brist på hävd mellan de två slåtterfrekvenserna. Dessa resultat tyder på att slåtter är en bättre skötselmetod. jämfört med bete, medan slåtter en gång per år har en något mer positiv effekt jämfört med slåtter vart tredje år. Artikel IV och V undersökte effekten av skötselmetoder på en större skala, genom att systematiskt gå igenom, granska och analysera data från studier som undersökt effekterna av bete och slåtter och olika slåtterfrekvenser, på floran och faunan i ängs- och hagmarker. Artikel IV analyserade data från 35 studier från hela världen som jämfört bete och slåtter, och fann en något mer positiv effekt av bete jämfört med slåtter på diversiteten av växt- och djurarter. Dock skiljde sig effekterna beroende på förhållandena i de undersökta gräsmarkerna, exempelvis beroende på geografi, gräsmarkstyp och tidigare skötsel. Artikel V analyserade data från 29 europeiska studier som jämfört slåtter en gång per år med slåtter vart femte, tredje eller vartannat år, eller slåtter två, tre eller fyra gånger per år. Analyserna visade på en något mer positiv effekt av slåtter oftare än en gång per år, men skillnaderna mellan slåtterfrekvenserna var små och de skiljde sig beroende på förhållandena i gräsmarkerna. Exempelvis så var en högre slåtterfrekvens bättre i mer produktiva gräsmarker. Resultaten från dessa två artiklar tyder på att bete är något bättre än slåtter, och att i mindre produktiva gräsmarker kan slåtter mer sällan än en gång per år, exempelvis vartannat år, vara ett sätt att använda de begränsade resurserna tillgängliga för skötsel på ett mer effektivt sätt. Resultaten från artiklarna i denna avhandling visar att olika skötselmetoder har olika effekt på diversiteten i ängs- och hagmarker. Dock var dessa skillnader relativt små, vilket tyder på att i viss utsträckning är den viktigaste faktorn att skötsel faktiskt sker, medan själva skötselmetoden är av mindre betydelse. Därför är det viktigt att basera valet av skötselmetod i ett specifikt fall på bevarandemål, abiotiska förhållanden, tidigare skötselmetoder, kostnaden och tillgängligheten för olika skötselmetoder samt tidigare forskning

Maintaining an open landscape: a 15-year multi-site experiment comparing seven management methods for semi-natural grasslands

<p>The data and publications presented here stems from a field trial started in Sweden ca 1972 (at one site still running in 2023). The purpose of the trial was to compare traditional management of semi-natural grasslands by grazing or annual mowing with five alternative management methods. At <strong>e</strong>leven locations in southern Sweden, block experiments were conducted evaluating seven treatments in 5 m * 20 m plots: grazing, annual mowing, annual spring burning, mowing every third year, mechanical removal of woody plants, herbicide control of woody plants, and untreated control. After approximately 13 years, trends for woody plants and species richness, and the occurrence of management-dependent plant species, low-grown species, and pollinator-attracting plant species were analysed. Overall, the annual mowing and grazing treatments resulted in fewer woody plants, the highest species richness, and more management-dependent, low-grown, and pollinator-attracting species. The untreated control plots showed the opposite effect, whereas less intense management (annual burning, mowing every third year, and mechanical and chemical treatments of woody plants) showed mixed and often intermediate effects. </p><p>On this ZENODO-page, one can find all the orginal publication, most in Swqedish. An article summarizing much of results can be found here: <a href="https://doi.org/10.1016/j.gecco.2023.e02721">https://doi.org/10.1016/j.gecco.2023.e02721</a></p&gt

Decline in lichen biodiversity on oak trunks due to urbanization Decline in lichen biodiversity on oak trunks due to urbanization

Abstract: Biodiversity often suffers from urbanization. In the present study, we focused on how the length of urbanization affects the richness of 17 epiphytic lichen species and their cover on large oaks in urban environments in a city of 100 000 inhabitants in SE Sweden. We also surveyed trees in adjacent rural areas, selected to have similar distributions of tree trunk circumference and surrounding oak density (within 300 m). Lichen richness and cover were lower on urban trees compared to rural trees. Furthermore, richness and cover decreased with the length of time that urban trees had been surrounded by houses. Most of the species that were analysed demonstrated a decline in occurrence with respect to the duration of housing development. The reduction in the probability of occurrence varied from 60% (Calicium viride, Evernia prunastri), 80% (Chrysothrix candelaris) to 90% (Ramalina spp. Ach.) during the 160-year period of urbanization considered. Therefore, even if valuable trees survive over the course of development, their lichen biota is likely to become depleted over time

The biodiversity cost of reducing management intensity in species-rich grasslands: Mowing annually vs. every third year

Mowing is an important management method for species-rich semi-natural grasslands in Europe. Since mowing is costly, it is important to find a balance between mowing frequency and conservation benefits. We compared vegetation data from eleven field trials situated in southern Sweden that involved two mowing regimes, annually and every third year, as well as a no-management control. After approximately 14 years, mowing every third year showed (i) a drop in species richness and Shannon and GiniSimpson diversity indices, (ii) an increase in woody species, and (iii) increases in tall-grown species. However, there were no apparent changes in (iv) species that were indicative of poor management, nor (v) those indicating good management. For one of the trials, data after 38 years were also evaluated. Compared with annual mowing, there were strong negative changes in the number of species in the untreated control, while the results were conflicting for mowing every third year. In conclusion, the expected loss of conservation values from reduced mowing intensity was 5060% of the loss after abandonment. The outcomes, however, varied among the eleven sites. (C) 2017 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.Funding Agencies|Swedish Board of Agriculture</p

Annual burning of semi-natural grasslands for conservation favours tall-grown species with high nectar production

Species-rich semi-natural grasslands in Europe are a main target for conservation efforts, and alternative methods to the traditional management of mowing or grazing would be welcome due to the difficulties in maintaining traditional management practices. One such method proposed is burning of grassland vegetation during late winter or spring. To evaluate the effects of annual spring burning vs annual mowing on semi-natural grassland vegetation, we compared the frequency of species in eleven field experiments in southern Sweden after ca 14 years. Out of the 88 species analyzed, five were more frequent in burnt plots compared with mowed plots (Vicia cracca, Cirsium arvense, Urtica dioica, Galium verum, Convallaria majalis). In contrast, 37 species were significantly less frequent in burnt plots compared with mowed ones, those with the largest differences being Ranunculus acris, Briza media, Veronica chamaedrys, Festuca ovina, Plantago lanceolata and Anthoxanthum odoratum. Tall-grown species and those with preferences for N-rich soils increased in frequency under an annual spring-burn regime, compared with annual mowing, as did species producing larger amounts of nectar. Hence, although vegetation composition becomes more trivial with annual spring burns, there might be long-term benefits for nectar-feeding insects.Funding Agencies|Swedish Environmental Protection Agency; Swedish Board of Agriculture</p