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  • Publication
    Accès libre
    Direct and indirect effects of urban gardening on aboveground and belowground diversity influencing soil multifunctionality
    (2019-7-5) ;
    Frey, David
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    Mäder, Paul
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    Stehle, Bernhard
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    Fliessbach, Andreas
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    Moretti, Marco
    Urban gardens are popular green spaces that have the potential to provide essential ecosystem services, support human well-being, and at the same time foster biodiversity in cities. We investigated the impact of gardening activities on five soil functions and the relationship between plant (600 spp.) and soil fauna (earthworms: 18 spp., springtails: 39 spp.) in 85 urban gardens (170 sites) across the city of Zurich (Switzerland). Our results suggest that high plant diversity in gardens had a positive effect on soil fauna and soil multifunctionality, and that garden management intensity decreased plant diversity. Indices of biological activity in soil, such as organic and microbial carbon and bacterial abundance, showed a direct positive effect on soil multifunctionality. Soil moisture and disturbance, driven by watering and tilling, were the driving forces structuring plant and soil fauna communities. Plant indicator values proved useful to assess soil fauna community structure, even in anthropogenic plant assemblages. We conclude that to enhance soil functions, gardeners should increase plant diversity, and lower management intensity. Soil protective management practices, such as applying compost, mulch or avoiding soil tilling, should be included in urban green space planning to improve urban biodiversity and nature’s contribution to people.
  • Publication
    Accès libre
    Litter decomposition driven by soil fauna, plant diversity and soil management in urban gardens
    (2019-3-1) ;
    Frey, David
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    Zanetta, Andrea
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    Rasche, Frank
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    Fliessbach, Andreas
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    Moretti, Marco
    In the face of growing urban densification, green spaces in cities, such as gardens, are increasingly important for biodiversity and ecosystem services. However, the influences of urban green space management on biodiversity and ecosystem functioning (BEF) relationships is poorly understood. We investigated the relationship between soil fauna and litter decomposition in 170 urban garden sites along a gradient of urbanisation intensity in the city of Zurich, CH. We used litter bags of 1 and 4 mm mesh size to evaluate the contribution of soil meso- and macrofauna on litter decomposition. By using multilevel structural equation models (SEM), we investigated direct and indirect environmental effects and management practices on litter decomposition and litter residue quality. We evaluated the role of taxonomic, functional and phylogenetic diversity of soil fauna species on litter decomposition, based on a sample of 120 species (81007 individuals; 39 collembola, 18 earthworm, 16 isopod, 47 gastropod species). We found highest litter decomposition rates using 4 mm mesh size litter bags, highlighting the importance of soil macrofauna. Urban warming, a proxy for urbanisation intensity, covaried positively, whereas soil disturbances, such as intensive soil and crop management, were negatively correlated with decomposition rates. Interestingly, soil fauna species richness decreased, with the exception of gastropods, and soil fauna abundance increased with urban warming. Our data also show that plant species richness positively affected litter decomposition by increasing soil fauna species richness and microbial activity. A multivariate analysis of organic compounds in litter residues confirmed the importance of soil fauna species richness and garden management on litter decomposition processes. Overall, we showed, that also in intensively managed urban green spaces, such as gardens, biodiversity of plants and soil fauna drives key ecosystem processes. Urban planning strategies that integrate soil protecting management practices may help to maintain important ecosystem services in this heavily used urban environment.
  • Publication
    Accès libre
    Impacts of urban gardening on soil quality, soil fauna and soil multifunctionality
    (2019) ; ;
    Fliessbach, Andreas
    ;
    Moretti, Marco
    Les jardins urbains sont des espaces verts populaires et importants. L’espace urbain est en pleine expansion à l’échelle mondiale, et les jardins urbains contribuent de plus en plus aux services écosystémiques, notamment au bien-être des citoyens et à la biodiversité en ville. Les pratiques horticoles déterminent la diversité des plantes et des insectes en surface et dans le sol. Toutefois, les effets de ces pratiques sur la qualité et les fonctions du sol ont été rarement étudiés. À cet effet, une évaluation de la diversité et de l’abondance des espèces faunistiques du sol a été réalisée sur 170 parcelles au sein de 85 jardins urbains à Zurich. Ces derniers ont été sélectionnés en fonction d’un gradient d’urbanisation et pour couvrir un spectre large des différentes pratiques horticoles, depuis les intensives cultures végétales annuelles intensives aux cultures pérennes extensives dominées par des fleurs et autres espèces herbacées. Une enquête a été élaborée concernant les pratiques des 85 jardiniers en collaboration avec les différents sous-projets : i) celui sur les services écosystémiques de support et de régulation, par exemple la pollinisation et le contrôle des parasites, et ii) celui sur la valeur sociale des jardins urbains. Cette enquête a ensuite servi à évaluer les déterminants de la qualité du sol, mesurés au travers d’une multitude d’indicateurs physiques, chimiques et biologiques. Au final, la qualité du sol est liée aux activités de jardinage et est principalement influencée par trois catégories d’utilisation : les légumes (plantation annuelle), les fleurs et les baies (végétation pérenne arbustive) et les pelouses (végétation pérenne herbacée). Les concentrations de métaux lourds sont associées à la proximité du trafic routier et des industries, mais pas à d’autres facteurs tels que les pratiques horticoles ou l’âge du jardin.
    Ensuite, la décomposition des matières organiques a été étudiée en utilisant des sachets de litière de deux maillages différents (1 et 4 mm) et deux sortes de litière (Zea mays L., feuilles et tiges). S’agissant de la litière, les taux de décomposition les plus élevés concernent les organismes de la macro- et de la mésofaune; ils sont plus élevés pour les feuilles, plus faciles à décomposer. Ici encore, les pratiques horticoles représentent un des principaux facteurs influant sur la décomposition de la matière organique ainsi que sur la diversité de la faune du sol (vers de terre, collemboles, isopodes et gastéropodes).
    Nous avons également trouvé une relation positive entre la richesse spécifique de la pédofaune (4 groupes taxonomiques, 120 espèces et 81’007 individus) et la richesse spécifique des espèces végétales en décomposition. Cela indique que, même dans les espaces verts urbains, la biodiversité stimule les services écosystémiques. En outre, nous avons évalué l’impact des trois types d’utilisation du jardin sur la faune et la multifonctionnalité des sols, en relation avec la production d’aliments et la fertilité du sol. Les pratiques horticoles n’ont pas seulement déterminé la diversité des plantes en surface, ils ont également eu des implications sur la pédofaune et les fonctions du sol. Les effets les plus importants sur la multifonctionnalité des sols sont liés à la variabilité des caractéristiques des sols. Nous avons constaté que, dans tous les sols de jardin, une qualité biologique élevée du sol a un effet positif sur sa multifonctionnalité, alors que l’intensité des pratiques diminue la diversité des plantes et celle la faune du sol.
    De plus, la richesse spécifique de la pédofaune diminue avec le degré d’urbanisation, mais l’abondance augmente. Les taux de décomposition sont également plus élevés dans les zones les plus urbanisées, mais aucun effet significatif n’a été constaté en lien avec la multifonctionnalité des sols.
    Cependant, peu d’études documentent l’effet des pratiques horticoles. Par conséquent, nous estimons qu’il existe un grand potentiel pour les futures recherches sur les écosystèmes de type jardins urbains, par exemple en ce qui concerne d’autres fonctions du sol comme stockage du carbone ou de l’eau, mais également les effets des pratiques culturales organiques sur la biodiversité en ville. Ainsi, de nombreux jardiniers utilisent encore des pesticides sans connaître les effets dommageables sur la biodiversité et la qualité du sol. À l’avenir, les études pourraient développer et analyser les pratiques de jardinage éco- logique sur la diversité en surface et souterraine et leurs effets sur la qualité des sols à long terme, par exemple par le biais d’une approche scientifique citoyenne.
    En général, nous avons souligné que pour maintenir des services écosystèmes importantes, les pratiques de protectrices du sol, comme l’application de compost ou de paillis, doivent être intégrées dans les stratégies des planifications d’espaces verts urbains, mais aussi au niveau des associations locales de jardins. Nous concluons que les jardins urbains ont le potentiel pour augmenter la biodiversité et des services écosystémiques urbaines, tout aussi bien qu’ils sont des points de rencontre de personnes et améliorant le bien-être humain.
    De manière générale, pour favoriser et maintenir des services écosystémiques performants, les pratiques de protection du sol, comme l’application de compost ou de paillis, doivent être intégrées dans les stratégies de planification d’espaces verts urbains, mais aussi au niveau des associations locales de jardins. Nous concluons que les jardins urbains ont le potentiel d’augmenter la biodiversité et les services écosystémiques urbains, tout autant qu’ils constituent des points de rencontre de personnes, améliorant ainsi les contacts et le bien-être humain., Urban gardens are important and at the same time popular greenspaces. As urban areas are expanding globally, urban gardens play an increasingly important role in contributing to essential ecosystem services, well-being of citizens, and biodiversity in a city. Gardening activities determine above- and belowground diversity of plants and insects. However, the effect of gardening activities on soil quality and soil functions have rarely been studied. For this purpose, a city-wide assessment of soil quality including key soil fauna species and soil functions was established on 170 plots in 85 urban gardens of the city of Zurich. They have been selected in accordance to an urbanisation gradient and to cover the spectrum of existing garden management practices, from intensively managed annual vegetable beds to extensively managed gardens dominated by perennial flowers and grass species. A management survey for the 85 participating gardeners was developed in collaboration with the subproject on aboveground ecosystem services, such as pollination and pest control, and the subproject studying the social value of urban gardens. This management survey was then used to assess drivers in soil quality, measured by a multitude of physical, chemical and biological soil quality indicators.
    Taken together, soil quality was shaped by garden management activities and was mainly determined by three urban garden land-use types: vegetables (annual vegetation), flowers and berries (perennial vegetation dominated by forbs), and lawn (perennial vegetation dominated by grasses). In addition, heavy metal concentrations were linked to the proximity to traffic and industry, but not to other factors such as garden management or garden age.
    Next, the soil function decomposition of organic material was investigated with litter bags of two different mesh sizes (1 and 4 mm) and litter types (Zea mays L. leaves and stems). In both litter types, we found the highest decomposition rates including both macro- and mesofauna species, but decomposition rates were higher in leaves, which are the better decomposable litter type. Garden management was again a main influencing factor affecting soil function decomposition and diversity of soil fauna species (earthworms, collembola, isopods and gastropods). We found a positive relationship of soil fauna species richness (4 taxonomic groups, 120 species and 81’007 individuals) as well as plant species richness with decomposition. This indicated that also in intensively managed urban greenspaces, such as urban gardens, biodiversity drives ecosystem services.
    Furthermore, we assessed the impact of the three garden land-use types on soil fauna and multiple soil functions, related to food production and soil quality. The management of specific garden land-use types not only determined the diversity of plants aboveground, it had also implications on soil fauna and soil functions belowground. The strongest effects influencing soil multifunctionality were caused by the differences in soil characteristics. We found that across all urban garden soils, high soil biological quality had a positive effect on soil multifunctionality, whereas management intensity decreased plant and soil fauna diversity, which had a positive effect on soil multifunctionality. Moreover, we found that soil fauna species richness most often decreased with urbanisation, but soil fauna abundance increased. Decomposition rates were also found to be higher in more urbanised areas, while no significant effect was found with soil multifunctionality.
    However, very little studies investigate current gardening practices. Therefore, we see a great potential of future investigations in urban garden ecosystems, for instance about other soil functions such as carbon or water storage potential, but also about effects of organic gardening practices on urban biodiversity. As an example, we have found that many gardeners still use pesticides in their gardens without knowing its detrimental effects on biodiversity and soil quality. Since the vast majority of urban gardeners are supportive of biodiversity, futures studies could develop and analyse ecological gardening practices on above- and belowground diversity and their effects on long-term soil quality, for example with a citizen science approach.
    Overall, we highlighted that soil protective management practices, such as applying compost or mulch, and lower management intensity need to be integrated in urban planning strategies on a citywide scale but also at the local garden association level, in order to maintain important ecosystem services. We conclude that urban gardens have the potential to increase urban biodiversity and important ecosystem services, while at the same time being meeting points for people with different social backgrounds and increasing human well-being.
  • Publication
    Accès libre
    Urban Soil Quality Assessment—A Comprehensive Case Study Dataset of Urban Garden Soils
    (2018-11-13) ;
    Moretti, Marco
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    Mäder, Paul
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    Zanetta, Andrea
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    Frey, David
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    Stehle, Bernhard
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    Kuhn, Anton
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    Munyangabe, Adolphe
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    Fliessbach, Andreas
  • Publication
    Accès libre
    A Gardener's Influence on Urban Soil Quality
    (2018-5-8) ;
    Moretti, Marco
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    Mäder, Paul
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    Zanetta, Andrea
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    Frey, David
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    Fliessbach, Andreas
    Gardens are hot spots for urban biodiversity and provide habitats for many plant and animal species, both above- and below-ground. Furthermore, gardens provide a wide range of ecosystem services, including carbon (C) storage and nutrient cycling. Although the soil is the foundation of sustainable gardens providing those ecosystem services, very little is known about the consequences of garden management on soil quality. Here we present a comprehensive assessment of urban garden soil quality, including biotic and abiotic site characteristics combined with land-use history and garden management information in a multivariate evaluation. A set of 44 soil quality indicators was measured at 170 sites of 85 gardens in the city of Zurich, Switzerland, comprising contrastingly managed garden habitats along a gradient of urban density. Taken together, our results show that garden management was the driving factor that influenced soil quality and soil functions. Eco-physiological soil quality indices were useful to identify differences in disturbance and intensity of soil use, showing highest microbial [microbial biomass (Cmic)/soil organic carbon (SOC)] and lowest metabolic (qCO2) quotients in perennial grass sites compared to annual vegetable sites. Despite the intensity of soil disturbance in annual vegetable and flower beds, the highest endogeic earthworm biomass and diversity were found in those habitats. Whereas decomposition of green tea bags was higher in grass sites. Soil heavy metal contents varied considerably and could not be linked with garden management practices, but with spatial patterns of industry and traffic. We conclude that understanding soil quality in urban ecosystems needs multi-indicator frameworks to capture the complexity of soil characteristics and the influencing factors in space and time. This study contributes to a better understanding of urban gardens and enhances the development of sustainable soil management strategies aimed at long-term improvement of soil quality and related ecosystem services in cities.