Metsä- ja niittyhabitaattien hoito kaupunkiluonnon monimuotoisuuden edistämiseksi : viestejä maakiitäjäisistä ja putkilokasveista

In this thesis I use carabid beetles (Coleoptera, Carabidae) and vascular plants to investigate the ecological effects of urbanization on forested and dry meadow habitats in the city of Helsinki, Finland. I also investigate factors that affect species diversity and the occurrence of rare and sensitive species in particular, in order to draft recommendations for habitat management for the enhancement of urban biodiversity. Urbanization gradient analyses are conducted using multivariate ordination analyses to elucidate assemblage level responses, ANOVA is applied to determine the assemblage level response of spruce forest carabid assemblages and GLMM is used to model individual species responses. The results suggest that, in contrast to Gray s suggestion, Preston s log-normal does not accurately describe the species distributions of carabid beetles in the studied habitats but rather they follow the predictions of Fisher s log series and Hubbell s unified neutral theory. I conclude that fragmentation, isolation and homogenization are the main problems regarding maintenance of urban biodiversity, and that biodiversity strategies should focus on the conservation of stenotopic species. In particular, habitats and ecologically important microhabitat conditions should be retained in as large and contiguous a form as possible. For instance, spruce forest habitats need to be managed to maintain shady, cool and moist conditions and dry meadows should be mown late in the season and the cut vegetation removed. Additionally, supplementation of habitat networks should be implemented, by habitat restoration and habitat creation, such as the construction of dry meadows on landfills and noise abatement banks.Vuoden 1992 Rio de Janeiron Earth Summit-konferenssin, sekä sen seurauksena syntyneen biodiversiteettisopimuksen jälkeen on kiinnitetty paljon huomiota maapallon luonnon monimuotoisuuden vähenemiseen. Kuitenkin päästrategia ongelman ratkaisemiseksi on edelleen arvokkaimpien kohteiden suojeleminen. Niiden ulkopuolella suojelemattomien alueiden heikentyminen ja tuhoutuminen jatkuu. Suojelualueet ovat yleensä syrjäisiä, eristyneitä ja sijaitsevat maaseudulla kun taas kaupungeissa luontoalueet vähenevät ja heikentyvät. Tässä työssä tarkastelen kahdenlaisia kaupunkialueilla sijaitsevia elinympäristöjä, metsiä ja niittyjä ja pohdin, miten niitä voitaisiin parhaiten hoitaa säilyttäen luonnon monimuotoisuus. Tulokseni viittaavat siihen, että kaupunkien kuusimetsät ovat yleensä liian harvennettuja, avoimia ja kuluneita metsälajeille. Sen sijaan, että kaupunkimetsiä hoidetaan ensisijaisesti virkistyskäyttöä varten, olisi syytä säilyttää myös enemmän alueita, jotka hoidetaan metsälajistoa varten. Tämä tarkoittaa, että niitä ei harvenneta, eikä kuivata ja alueille jätettäisiin lahopuuta. Tunnettujen arvoniittyjen lisäksi myös muiden ruohikkoisten alueiden ja niittyjen lajit hyötyisivät luonnon monimuotoisuutta edistävien hoitostrategian käytöstä. Näin vaativammille lajeille sopivaa elinympäristön määrää saisi kasvatettua ja lajisto hyötyisi. Maakiitäjäisten tapauksessa lentokykyiset ja pienet lajit yleensä sietävät kaupungistumista parhaiten, kun taas lentokyvyttömillä ja suurikokoisilla lajeilla on taipumus kadota kaupunkien lajistoista. Kasvien kohdalla maaperän pH ja ravinnepitoisuudet ovat tärkeimmät kasvilajistoon vaikuttavat tekijät, ja typpeä suosivien lajien osuus kasvaa kaupungistumisen lisääntyessä. Niitto ja heinän poisto osoittautuivat tehokkaiksi tavoiksi vähentää maaperän ravinnepitoisuuksia ja kasvattaa harvinaisten ja herkkien kasvilajien osuutta lajistossa. Kasvillisuus kartoitettiin määrittämällä kasvilajeja neliömetrin ruuduista ja maakiitäjäislajistot tutkittiin käyttämällä kuoppapyydyksiä. Nämä pyydykset koostuivat muovimukeista, jotka kaivettiin maahan ja joihin kaadettiin fiksatiivinestettä näytteiden säilymiseksi. Pyydyksien päälle asetettiin muoviset kannet estämään sadeveden ja roskien pääsy pyydykseen. Käytännön tasolla tärkeimmät tutkimustulokseni ovat hoito-ohjeita, joiden avulla voidaan edistää kaupunkielinympäristöjen luonnon monimuotoisuutta. Arvokkaiden kohteiden hoitamisen lisäksi vaativimpien lajien elinmahdollisuuksia tulisi edistää hoitamalla laajempia alueita metsiä ja ruohikoita luonnon monimuotoisuutta varten, sekä perustamalla täydentäviä elinympäristöjä, kuten tekoniittyjä. Vaikka kaupungistumisella on negatiivisia vaikutuksia lajistoihin, voidaan sopivilla hoitostrategioilla tehokkaasti edistää luonnon monimuotoisuutta

Conservation, restoration and biodiversity of Palaearctic grasslands - Editorial to the 6th EDGG special issue in Hacquetia

This special issue is a collection of articles about the conservation, restoration and biodiversity of Palaearctic grasslands and was initiated by the Eurasian Dry Grassland Group at the 15th Eurasian Dry Grassland Conference (EDGC), held at Graz, Austria in 2019. The papers in this special issue cover a range of grassland habitats from montane dry grasslands to lowland sandy grasslands, feathergrass steppes and meadow steppes, and focus on the biodiversity values, conservation issues and restoration prospects of Palaearctic grasslands. We hope that the articles in this special issue will contribute to a better understanding of the ecology of grasslands and support their more effective conservation.Peer reviewe

Conservation, restoration and biodiversity of Palaearctic grasslands - Editorial to the 6th EDGG special issue in Hacquetia

This special issue is a collection of articles about the conservation, restoration and biodiversity of Palaearctic grasslands and was initiated by the Eurasian Dry Grassland Group at the 15th Eurasian Dry Grassland Conference (EDGC), held at Graz, Austria in 2019. The papers in this special issue cover a range of grassland habitats from montane dry grasslands to lowland sandy grasslands, feathergrass steppes and meadow steppes, and focus on the biodiversity values, conservation issues and restoration prospects of Palaearctic grasslands. We hope that the articles in this special issue will contribute to a better understanding of the ecology of grasslands and support their more effective conservation.Peer reviewe

Diving beetle (Coleoptera: Dytiscidae) community dissimilarity reveals how low landscape connectivity restricts the ecological value of urban ponds.

Context: Structural and functional connectivity, as subconcepts of landscape connectivity, are key factors in biodiversity conservation and management. Previous studies have focused on the consequences of connectivity for populations of terrestrial organisms, which may not be appropriate for aquatic organisms. Objectives: As landscape connectivity critically affects the potential value of ponds for biodiversity, here we used diving beetles (Dytiscidae), an indicator taxon of wetland biodiversity, to investigate how structural connectivity affects functional connectivity to aquatic invertebrates in an urban landscape. Methods: We assessed pairwise similarities of dytiscid community, i.e. the variation of species composition between clustered and isolated ponds in the Helsinki Metropolitan Area, Finland. We investigated how dytiscid community similarity is affected by Euclidean distances between ponds, as an indicator of structural connectivity. Results: We found that clustered ponds shared more species than isolated ponds. Dytiscid species community similarity responded negatively to increasing Euclidean distance between ponds. Effectively dispersing species were widely distributed across the landscape, while poor dispersers were scarcely distributed in the same landscape. Conclusions: Structural connectivity determines which species are able to disperse successfully, with poor dispersers restricted to well-connected ponds. The different responses of effective dispersers and poor dispersers to the same structural connectivity indicate that functional connectivity determines species composition. We recommend providing well-connected aquatic habitats in urban landscapes and the implementation of measures to reduce isolation of wetland assemblages. Even clustered ponds need dispersal from other habitats to ensure their contribution to urban biodiversity.Peer reviewe

Microhabitats with emergent plants counterbalance the negative effects of fish presence on diving beetle (Coleoptera: Dytiscidae) diversity in urban ponds

Aquatic plants are important prey refuges for aquatic organisms, and their species richness is positively related with aquatic invertebrate species richness. Yet, it is unclear how the quantity of refuges, i.e. aquatic vegetation cover, affect aquatic invertebrate assemblages and their habitat use under different levels of predation risk (e.g. in the presence or absence of fish), nor at different scales (i.e. microhabitat and pond scales). Here, we investigated how provision of refuges affects diving beetle (Dytiscidae) species richness and abundance in the presence and absence of fish predators. We sampled diving beetles (Dytiscidae) with 1-L activity traps and estimated emergent plant cover at both the pond and microhabitat scales. We found that plant cover affected dytiscid populations differently: At the pond scale, dytiscid presence was positively correlated with increasing plant cover, both with and without fish, indicating the importance of emergent plants for aquatic biodiversity. At the microhabitat scale, dytiscid species richness and abundance were positively correlated with increasing plant cover in ponds with fish, but there was no such relationship in ponds without fish, emphasizing that the level of predation risk can alter prey species’ use of prey refuges. Our findings provide evidence that the availability of both vegetated and non-vegetated microhabitats can benefit aquatic invertebrates. We suggest maintaining variation in the provision of emergent plant cover, to retain high habitat heterogeneity in urban ponds and to enhance freshwater biodiversity.Peer reviewe

Bees and pollination in grassland habitats in Helsinki (Finland) are diverse but dominated by polylectic species

Bees constitute a key taxon of grassland ecosystems and are the main providers of the essential Ecosystem Service of pollina-tion. We studied bee assemblages of 17 grassland sites in Helsinki, Finland. Bees were sampled using coloured pan traps. The total catch comprised 353 individuals of 35 species. The most abundant species were Lasioglossum leucopus, Lasioglossum lucidulum and Bombus lucorum complex. We used NMDS ordination to depict habitat associations, and GLMM to model the responses of species and trophic groups to habitat type and level of urbanization. Polylectic ground-nesting species were the most abundant trait group. There were only few records of oligolectic species, which showed a significant preference for areas with the lowest level of urbanization. We recommend the provision and maintenance of a diverse range of grassland habitats, with particular attention to the conservation of late successional meadow habitats.(c) 2023 The Authors. Published by Elsevier GmbH on behalf of Gesellschaft fur okologie. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)Peer reviewe

Ecology and Conservation of Steppes and Semi-Natural Grasslands

Palaearctic grasslands encompass a diverse variety of habitats, many of high nature value and vulnerability. The main challenges are climate-change, land-use change, agricultural intensification and abandonment. Many measures are in place to address these challenges, through restoration and appropriate management, though more work is necessary. We present eight studies from China/Germany, Greece, Kazakhstan, Russia and Ukraine. The papers cover a wide range of grassland and steppe habitats and cover vegetation ecology, syntaxonomy and zoology. We also conducted a systematic search on steppe and grassland diversity. The greatest number of studies was from China, followed by Germany and England. We conclude that the amount of research being carried out on Eurasian grasslands is inadequate considering their high levels of biodiversity and vulnerability. We hope to encourage readers to address current major challenges, such as how to manage grasslands for the benefit of diverse taxa, to ensure that conservation initiatives concentrate on sites where there is good potential for success and for the generation of realistic and viable conservation strategies.Peer reviewe

The challenge of abandonment for the sustainable management of Palaearctc natural and semi-natural grasslands

Disturbance by biomass removal is a crucial mechanism maintaining the diversity of Palaearctic grasslands, which are unique biodiversity hotspots. Te century-long traditional land use of mowing, grazing and burning, has been fundamentally changed in many parts of the Palaearctic. Due to socio-economic changes, large areas of former pastures and meadows have been abandoned, leading to a succession towards secondary scrublands or forest and the encroachment of competitor grass species, all leading to a decrease in biodiversity. Here we report the causes and consequences of the cessation of traditional grassland management regimes, provide strategies for reducing the impact of abandonment and consider these from the perspective of sustainability. We consider the possibilities for initiating sustainable management regimes in the contemporary socio-economic environment, and discuss the prospectsand limitation of alternative management regimes in the conservation of grassland biodiversity. Tese themes are also the core topics of this Special Feature, edited by the EDGG. We hope that this Special Feature will encourage steps towards more sustainable strategies for the conservation of Palaearctic grasslands and the integration of the sustainability perspective into their conservation

Ecology and Conservation of Steppes and Semi-Natural Grasslands

Palaearctic grasslands encompass a diverse variety of habitats, many of high nature value and vulnerability. The main challenges are climate-change, land-use change, agricultural intensification and abandonment. Many measures are in place to address these challenges, through restoration and appropriate management, though more work is necessary. We present eight studies from China/Germany, Greece, Kazakhstan, Russia and Ukraine. The papers cover a wide range of grassland and steppe habitats and cover vegetation ecology, syntaxonomy and zoology. We also conducted a systematic search on steppe and grassland diversity. The greatest number of studies was from China, followed by Germany and England. We conclude that the amount of research being carried out on Eurasian grasslands is inadequate considering their high levels of biodiversity and vulnerability. We hope to encourage readers to address current major challenges, such as how to manage grasslands for the benefit of diverse taxa, to ensure that conservation initiatives concentrate on sites where there is good potential for success and for the generation of realistic and viable conservation strategies

The Eurasian Dry Grassland Group (EDGG) in 2016-2017

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