| 1. |
- Allan, Eric, et al.
(författare)
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Interannual variation in land-use intensity enhances grassland multidiversity
- 2014
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 111:1, s. 308-313
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Tidskriftsartikel (refereegranskat)abstract
- Although temporal heterogeneity is a well-accepted driver of biodiversity, effects of interannual variation in land-use intensity (LUI) have not been addressed yet. Additionally, responses to land use can differ greatly among different organisms; therefore, overall effects of land-use on total local biodiversity are hardly known. To test for effects of LUI (quantified as the combined intensity of fertilization, grazing, and mowing) and interannual variation in LUI (SD in LUI across time), we introduce a unique measure of whole-ecosystem biodiversity, multidiversity. This synthesizes individual diversity measures across up to 49 taxonomic groups of plants, animals, fungi, and bacteria from 150 grasslands. Multidiversity declined with increasing LUI among grasslands, particularly for rarer species and aboveground organisms, whereas common species and belowground groups were less sensitive. However, a high level of interannual variation in LUI increased overall multidiversity at low LUI and was even more beneficial for rarer species because it slowed the rate at which the multidiversity of rare species declined with increasing LUI. In more intensively managed grasslands, the diversity of rarer species was, on average, 18% of the maximum diversity across all grasslands when LUI was static over time but increased to 31% of the maximum when LUI changed maximally over time. In addition to decreasing overall LUI, we suggest varying LUI across years as a complementary strategy to promote biodiversity conservation.
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| 2. |
- Birkhofer, Klaus, et al.
(författare)
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Density-dependent and -independent effects on the joint use of space by predators and prey in terrestrial arthropod food-webs
- 2011
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Ingår i: Oikos. - : Wiley. - 1600-0706 .- 0030-1299. ; 120:11, s. 1705-1711
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Tidskriftsartikel (refereegranskat)abstract
- The spatial distribution of predators and their prey is affected by their joint use of space. While the formation of such spatial patterns may be driven by density-dependent and -independent factors our knowledge on the contribution of different land-use activities on the formation of spatial patterns between predators and prey remains very limited. Agriculture is one of the most prevailing land-use activities with strong effects on invertebrate densities and structural habitat conditions. Here, we used replicated conventionally and organically managed winter wheat fields to investigate the effects of agricultural land-use on the spatial patterns of generalist predators and decomposer prey. We then identified the explanatory power of density-dependent (prey and predator activity density) and density-independent (vegetation structure) predictors for the observed spatial patterns. Generalist predators were regularly distributed only in conventionally managed fields and this pattern intensified with decreasing Collembola prey availability and increasing spider activity density. Segregation between carabid and spider predators was strongest in fields with lowest wheat plant height, suggesting more intense intraguild interactions in structurally less complex habitats. Collembola were aggregated independent of management and aggregation was strongest in fields with highest Collembola and carabid activity density. Spiders and Collembola prey were associated, but higher aphid densities under conventional management weakened or interrupted this spatial relationship. We conclude that active control of crop plant physiognomy by growth hormones and herbicides in conventionally managed fields promotes predator–predator segregation and that a high availability of aphid prey seems to decouple predator–Collembola prey associations. Our results emphasise the need for a more mechanistic understanding of the effects of land-use on the formation of spatial patterns and species interactions, especially under scenarios of environmental change and an ongoing loss of biodiversity.
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| 3. |
- Birkhofer, Klaus, et al.
(författare)
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Ecosystem services - current challenges and opportunities for ecological research
- 2015
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Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media SA. - 2296-701X. ; 2:12 January 2015
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Forskningsöversikt (refereegranskat)abstract
- e concept of ecosystem services was originally developed to illustrate the benefits that natural ecosystems generate for society and to raise awareness for biodiversity and ecosystem conservation. In this article we identify major challenges and opportunities for ecologists involved in empirical or modeling ecosystem service research. The first challenge arises from the fact that the ecosystem service concept has not been generated in the context of managed systems. Ecologists need to identify the effect of anthropogenic interventions in order to propose practices to benefit service-providing organisms and associated services. The second challenge arises from the need to evaluate relationships between indicators of ecosystem services that are collected in ecological studies while accounting for uncertainties of ecological processes that underlie these services. We suggest basing the assessment of ecosystem services on the utilization of sets of indicators that cover aspects of service-providing units, ecosystem management and landscape modification. The third challenge arises from the limited understanding of the nature of relationships between services and a lack of a general statistical framework to address these links. To manage ecosystem service provisioning, ecologists need to establish whether services respond to a shared driver or if services are directly linked to each other. Finally, studies relating biodiversity to ecosystem services often focus on services at small spatial or short temporal scales, but research on the protection of services is often directed toward services providing benefits at large spatial scales. Ecological research needs to address a range of spatial and temporal scales to provide a multifaceted understanding of how nature promotes human well-being. Addressing these challenges in the future offers a unique opportunity for ecologists to act as promoters for the understanding about how to conserve benefits gained from nature.
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| 4. |
- Birkhofer, Klaus, et al.
(författare)
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General Relationships between Abiotic Soil Properties and Soil Biota across Spatial Scales and Different Land-Use Types.
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:8
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Tidskriftsartikel (refereegranskat)abstract
- Very few principles have been unraveled that explain the relationship between soil properties and soil biota across large spatial scales and different land-use types. Here, we seek these general relationships using data from 52 differently managed grassland and forest soils in three study regions spanning a latitudinal gradient in Germany. We hypothesize that, after extraction of variation that is explained by location and land-use type, soil properties still explain significant proportions of variation in the abundance and diversity of soil biota. If the relationships between predictors and soil organisms were analyzed individually for each predictor group, soil properties explained the highest amount of variation in soil biota abundance and diversity, followed by land-use type and sampling location. After extraction of variation that originated from location or land-use, abiotic soil properties explained significant amounts of variation in fungal, meso- and macrofauna, but not in yeast or bacterial biomass or diversity. Nitrate or nitrogen concentration and fungal biomass were positively related, but nitrate concentration was negatively related to the abundances of Collembola and mites and to the myriapod species richness across a range of forest and grassland soils. The species richness of earthworms was positively correlated with clay content of soils independent of sample location and land-use type. Our study indicates that after accounting for heterogeneity resulting from large scale differences among sampling locations and land-use types, soil properties still explain significant proportions of variation in fungal and soil fauna abundance or diversity. However, soil biota was also related to processes that act at larger spatial scales and bacteria or soil yeasts only showed weak relationships to soil properties. We therefore argue that more general relationships between soil properties and soil biota can only be derived from future studies that consider larger spatial scales and different land-use types.
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| 5. |
- Birkhofer, Klaus, et al.
(författare)
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Global metawebs of spider predation highlight consequences of land-use change for terrestrial predator–prey networks
- 2017
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Ingår i: Adaptive Food Webs : Stability and Transitions of Real and Model Ecosystems - Stability and Transitions of Real and Model Ecosystems. - : Cambridge University Press. - 9781316871867 - 9781107182110 ; , s. 193-213
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Bokkapitel (refereegranskat)abstract
- Land-Use Change and Terrestrial Predator–Prey Networks Land-use change, here defined as the conversion of one land-use type into another (e.g., forest to arable land), affects biodiversity and biotic interactions worldwide (Sala et al., 2000). Although there has been large regional variation in the extent of agricultural expansion and abandonment in Europe in the past 50 years (Rabbinge and van Diepen, 2000), there has been a general trend that forest has expanded at the expense of agricultural land (Kankaanpäa and Carter, 2004; Rounsevell et al., 2006). The patterns have been similar in North America the past decades (Smith et al., 2010). Globally, particularly in developing countries, the general pattern has instead been agricultural expansion (Smith et al., 2010), threatening forest ecosystems (DeFries et al., 2010; Lambin and Meyfroidt, 2011; but see Angelsen, 2010). In fact, models predict an increase of cropland between 10 and 25% up to 2050, mainly due to agricultural expansion in developing countries (Schmitz et al., 2014). Natural and semi-natural non-forest ecosystems are primarily threatened by a conversion to pasture land (Schmitz et al., 2014) or by cultivation with biofuels (Havlík et al., 2011). Climate change is an important additional driver of land-use conversion, as the range of crop species contract or expand (Olesen and Bindi, 2002) and as forests adapt to changing climatic conditions (Spittlehouse and Stewart, 2004). In the past, effects of land-use change were often exclusively assessed by their impact on species richness (Tilman et al., 2001). Today, it has increasingly become evident that we need metrics that capture additional features of biological communities to understand consequences of land-use change on ecosystem functions and the provision of ecosystem services (Tylianakis et al., 2007; Diehl et al., 2013). Trophic interactions that link species in food webs are important components that modulate functions provided by biological communities (Laliberté and Tylianakis, 2010; Tylianakis et al., 2010; Thompson et al., 2012). For example, the loss of large apex predators from an ecosystem due to anthropogenic disturbance may cascade through the food chain and lead to drastic effects on primary producers (Estes et al., 2011). Predator populations are often severely affected by anthropogenic disturbances (Attwood et al., 2008). Consequently, the conversion from one major land-use type into another may alter predator–prey interactions (Ives et al., 2005) and the provision of predator-mediated ecosystem services such as the control of agricultural pests (conservation biological control; Barbosa, 1998).
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| 6. |
- Birkhofer, Klaus, et al.
(författare)
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Grassy margins along organically managed cereal fields foster trait diversity and taxonomic distinctness of arthropod communities
- 2014
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Ingår i: Insect Conservation and Diversity. - : Wiley. - 1752-4598 .- 1752-458X. ; 7:3, s. 274-287
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Tidskriftsartikel (refereegranskat)abstract
- It is not known if grassy margins contribute to the conservation of biodiversity if situated along organically managed cereal fields as the contrast in environmental conditions between fields and margins may be too small in absence of pesticide applications. Communities of spiders, ground beetles, true bugs and aphids were sampled in 2years along transects from the centre of organically managed cereal fields into adjacent grassy margins. Based on species richness, abundances, ecological and body size traits of species and taxonomic distinctness between species, communities were compared between organically managed cereal fields and their grassy margins. The species richness, abundance and variation in taxonomic distinctness of true bugs were significantly higher in grassy margins. For spiders and ground beetles, these metrics were either higher in cereal fields or did not differ significantly. At the species level, spiders living under stones or in soil crevices, as well as phytophagous ground beetles and true bugs that overwinter as eggs benefited from grassy margins. True bug communities in cereal fields were dominated by a few abundant species, whereas communities in margins were rather dominated by a few large species. Our comprehensive analyses highlight the importance of accounting for species identities and biology in biodiversity studies. The traits that characterised arthropod species that benefited from margins are not characteristic for pest species. Grassy margins along organic fields therefore represent an important agri-environmental scheme for the conservation of several arthropod taxa and margins should not be removed to increase the crop production area in organically managed cereal fields.
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| 7. |
- Birkhofer, Klaus, et al.
(författare)
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Land-use effects on the functional distinctness of arthropod communities
- 2015
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Ingår i: Ecography. - : Wiley. - 1600-0587 .- 0906-7590. ; 38:9, s. 889-900
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Tidskriftsartikel (refereegranskat)abstract
- Land-use change is a major driver of the global loss of biodiversity, but it is unclear to what extent this also results in a loss of ecological traits. Therefore, a better understanding of how land-use change affects ecological traits is crucial for efforts to sustain functional diversity. To this end we tested whether higher species richness or taxonomic distinctness generally leads to increased functional distinctness and whether intensive land use leads to functionally more narrow arthropod communities. We compiled species composition and trait data for 350 species of terrestrial arthropods (Araneae, Carabidae and Heteroptera) in different land-use types (forests, grasslands and arable fields) of low and high land-use intensity. We calculated the average functional and taxonomic distinctness and the rarified trait richness for each community. These measures reflect the range of traits, taxonomic relatedness and number of traits that are observed in local communities. Average functional distinctness only increased significantly with species richness in Carabidae communities. Functional distinctness increased significantly with taxonomic distinctness in communities of all analyzed taxa suggesting a high functional redundancy of taxonomically closely related species. Araneae and Heteroptera communities had the expected lower functional distinctness at sites with higher land-use intensity. More frequently disturbed land-use types such as managed grasslands or arable fields were characterized by species with smaller body sizes and higher dispersal abilities and communities with lower functional distinctness or trait richness. Simple recommendations about the conservation of functional distinctness of arthropod communities in the face of future land-use intensification and species loss are not possible. Our study shows that these relationships depend on the studied taxa and land-use type. However, for some arthropod groups functional distinctness is threatened by intensification and conversion from less to more frequently disturbed land-uses.
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| 8. |
- Birkhofer, Klaus, et al.
(författare)
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Land-use type and intensity differentially filter traits in above- and below-ground arthropod communities
- 2017
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 86:3, s. 511-520
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Tidskriftsartikel (refereegranskat)abstract
- Along with the global decline of species richness goes a loss of ecological traits. Associated biotic homogenization of animal communities and narrowing of trait diversity threaten ecosystem functioning and human well-being. High management intensity is regarded as an important ecological filter, eliminating species that lack suitable adaptations. Below-ground arthropods are assumed to be less sensitive to such effects than above-ground arthropods. Here, we compared the impact of management intensity between (grassland vs. forest) and within land-use types (local management intensity) on the trait diversity and composition in below- and above-ground arthropod communities. We used data on 722 arthropod species living above-ground (Auchenorrhyncha and Heteroptera), primarily in soil (Chilopoda and Oribatida) or at the interface (Araneae and Carabidae). Our results show that trait diversity of arthropod communities is not primarily reduced by intense local land use, but is rather affected by differences between land-use types. Communities of Auchenorrhyncha and Chilopoda had significantly lower trait diversity in grassland habitats as compared to forests. Carabidae showed the opposite pattern with higher trait diversity in grasslands. Grasslands had a lower proportion of large Auchenorrhyncha and Carabidae individuals, whereas Chilopoda and Heteroptera individuals were larger in grasslands. Body size decreased with land-use intensity across taxa, but only in grasslands. The proportion of individuals with low mobility declined with land-use intensity in Araneae and Auchenorrhyncha, but increased in Chilopoda and grassland Heteroptera. The proportion of carnivorous individuals increased with land-use intensity in Heteroptera in forests and in Oribatida and Carabidae in grasslands. Our results suggest that gradients in management intensity across land-use types will not generally reduce trait diversity in multiple taxa, but will exert strong trait filtering within individual taxa. The observed patterns for trait filtering in individual taxa are not related to major classifications into above- and below-ground species. Instead, ecologically different taxa resembled each other in their trait diversity and compositional responses to land-use differences. These previously undescribed patterns offer an opportunity to develop management strategies for the conservation of trait diversity across taxonomic groups in permanent grassland and forest habitats.
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| 9. |
- Birkhofer, Klaus, et al.
(författare)
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Soil fauna feeding activity in temperate grassland soils increases with legume and grass species richness
- 2011
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Ingår i: Soil Biology & Biochemistry. - : Elsevier BV. - 0038-0717. ; 43:10, s. 2200-2207
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Tidskriftsartikel (refereegranskat)abstract
- Edaphic fauna contributes to important ecosystem functions in grassland soils such as decomposition and nutrient mineralization. Since this functional role is likely to be altered by global change and associated shifts in plant communities, a thorough understanding of large scale drivers on below-ground processes independent of regional differences in soil type or climate is essential. We investigated the relationship between abiotic (soil properties, management practices) and biotic (plant functional group composition, vegetation characteristics, soil fauna abundance) predictors and feeding activity of soil fauna after accounting for sample year and study region. Our study was carried out over a period of two consecutive years in 92 agricultural grasslands in three regions of Germany, spanning a latitudinal gradient of more than 500 km. A structural equation model suggests that feeding activity of soil fauna as measured by the bait-lamina test was positively related to legume and grass species richness in both years. Most probably, a diverse vegetation promotes feeding activity of soil fauna via alterations of both microclimate and resource availability. Feeding activity of soil fauna also increased with earthworm biomass via a pathway over Collembola abundance. The effect of earthworms on the feeding activity in soil may be attributed to their important role as ecosystem engineers. As no additional effects of agricultural management such as fertilization, livestock density or number of cuts on bait consumption were observed, our results suggest that the positive effect of legume and grass species richness on the feeding activity in soil fauna is a general one that will not be overruled by regional differences in management or environmental conditions. We thus suggest that agri-environment schemes aiming at the protection of belowground activity and associated ecosystem functions in temperate grasslands may generally focus on maintaining plant diversity, especially with regard to the potential effects of climate change on future vegetation structure.
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| 10. |
- Brose, Ulrich, et al.
(författare)
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Spatial aspects of food webs
- 2005
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Ingår i: Dynamic Food Webs. - London, UK : Elsevier. - 9780120884582 - 0120884585 ; , s. 463-469
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Konferensbidrag (refereegranskat)abstract
- Aspects of spatial scale have until recently been largely ignored in empirical and theoretical food web studies (e.g., Cohen & Briand 1984, Martinez 1992, but see Bengtsson et al. 2002, Bengtsson & Berg, this book). Most ecologists tend to conceptualize and represent food webs as static representations of communities, depicting a community assemblage as sampled at a particular point in time, or highly aggregated trophic group composites over broader scales of time and space (Polis et al. 1996). Moreover, most researchers depict potential food webs, which contain all species sampled and all potential trophic links based on literature reviews, several sampling events, or laboratory feeding trials. In reality, however, not all these potential feeding links are realized as not all species co-occur, and not all samples in space or time can contain all species (Schoenly & Cohen 1991), hence, yielding a variance of food web architecture in space (Brose et al. 2004). In recent years, food web ecologists have recognized that food webs are open systems – that are influence by processes in adjacent systems – and spatially heterogeneous (Polis et al. 1996). This influence of adjacent systems can be bottom-up, due to allochthonous inputs of resources (Polis & Strong 1996, Huxel & McCann 1998, Mulder & De Zwart 2003), or top-down due to the regular or irregular presence of top predators (e.g., Post et al. 2000, Scheu 2001). However, without a clear understanding of the size of a system and a definition of its boundaries it is not possible to judge if flows are internal or driven by adjacent systems. Similarly, the importance of allochthony is only assessable when the balance of inputs and outputs are known relative to the scale and throughputs within the system itself. At the largest scale of the food web – the home range of a predator such as wolf, lion, shark or eagle of roughly 50 km2 to 300 km2 –the balance of inputs and outputs caused by wind and movement of water may be small compared to the total trophic flows within the home range of the large predator (Cousins 1990). Acknowledging these issues of space, Polis et al (1996) argued that progress toward the next phase of food web studies would require addressing spatial and temporal processes. Here, we present a conceptual framework with some nuclei about the role of space in food web ecology. Although we primarily address spatial aspects, this framework is linked to a more general concept of spatio-temporal scales of ecological research.
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