1. |
- Lundblad, M, et al.
(author)
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Stand transpiration and sapflow density in relation to weather, soil moisture and stand characteristics
- 2002
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In: Basic and Applied Ecology. - : Elsevier BV. - 1618-0089 .- 1439-1791. ; 3:3, s. 229-243
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Journal article (peer-reviewed)abstract
- Sapflow density was measured in six stands in a boreal forest in central Sweden, to assess its dependence on soil moisture and stand characteristics. The stands were mixed and pure Scots pine and Norway spruce stands, which were between 34 and 105 years old. Sapflow was measured in 12 trees per stand using the Granier method during two contrasting growing seasons; one warm and dry and one wet and cool. The canopy conductance of the stands was estimated by the inverse of the Penman-Monteith equation, using time-lag-adjusted sapflow as input. Maximum canopy conductance varied between 8 mm s(-1) and 88 mm s(-1) for the stand with the lowest and highest conductance, respectively. Transpiration was higher in the dry, warm season, mean values for the different stands ranging between 1.30 to 4.64 mm day(-1) during July to September. The corresponding range in the wet, cool season was 0.95 to 2.65 mm day(-1). Besides climatic factors, stand age, stem density and diameter explained most of the variation in sapflow density. By use of multiple regression analysis for 5-day periods it was possible to estimate sapflow density and transpiration for a larger area of the forest. This upscaled area) transpiration was compared with evaporation measured by an eddy-correlation system located centrally in the area. It was shown that areal transpiration constituted 78% of total evaporation in the warm, dry season and 52% in the wet, cool season. It was not possible to establish with confidence a critical limit for soil water at which transpiration began to be reduced, mainly because of wide scatter in the relationship between potential and actual transpiration.
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2. |
- Ajal, James, et al.
(author)
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Intercropping drives plant phenotypic plasticity and changes in functional trait space
- 2022
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In: Basic and Applied Ecology. - : Elsevier BV. - 1439-1791 .- 1618-0089. ; 61, s. 41-52
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Journal article (peer-reviewed)abstract
- The relevance of intercropping, where two or more crop species are simultaneously grown on the same land space, is growing due to its potential for improving resource use and maintaining stable yields under variable weather conditions. However, the actual growth of intercropped species may differ resulting from the idiosyncratic effect of crop diversity, and with this, the realized benefits from intercrops are found to depend critically on the cultivar, species, management and environmental conditions. This study aimed to apply a trait-based approach, in which ecological niche spaces are defined through n-dimensional hypervolumes, to identify the contribution of species/cultivar, cultivation design (sole crop or intercrop) and management (low or high fertilization) to the trait diversity of four crop species, pea-barley and faba bean-wheat, when grown as sole crops and intercrops. Four traits were used as trait axes for the trait space analysis: canopy height, shoot biomass, tiller/node number, and grain yield. We found that trait spaces differed with crop species and cultivars, and whether they were grown as intercrops or sole crops. Trait spaces differed between high and low fertilization only for the cereals grown in the more productive site (i.e. Denmark). Species grown as intercrops had larger volumes than when grown as sole crops, as a result of trait plasticity. This response to intercropping was apparent in almost all the species grown in Sweden and Denmark, except for wheat in Denmark. The study demonstrated that individual species responded to intercropping compared to sole cropping through the plasticity of traits, which influenced the shape of the hypervolumes to divide up the trait space between the species. The findings are important in illustrating the plastic responses of arable crops, which are relevant for understanding the productivity of species grown in intercrops as compared to sole crops.
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3. |
- Andersson, Georg, et al.
(author)
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Landscape heterogeneity and farming practice alter the species composition and taxonomic breadth of pollinator communities
- 2013
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In: Basic and Applied Ecology. - : Elsevier BV. - 1618-0089 .- 1439-1791. ; 14:7, s. 540-546
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Journal article (peer-reviewed)abstract
- Effects of landscape heterogeneity and farming practice on species composition are less well known than those on species richness, in spite of the fact that community composition can be at least as important for ecosystem services, such as pollination. Here, we assessed the effect of organic farming and landscape heterogeneity on pollinator communities, focusing on multivariate patterns in species composition and the taxonomic breadth of communities. By relating our results to patterns observed for species richness we show that: (1) species richness generally declines with decreasing landscape heterogeneity, but taxonomic breadth only declines with landscape heterogeneity on conventionally managed farms. We further highlight the importance to provide results of species composition analyses as (2) primarily hoverfly species benefited from organic farming, but three bee species from different families were favoured by conventionally managed farms and (3) two hoverfly species with aphidophagous larvae showed contrasting responses to landscape heterogeneity. These results advance the understanding of how landscape heterogeneity and farming practices alter insect communities and further suggest that diversity patterns need to be analysed beyond species richness to fully uncover consequences of agricultural intensification.
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4. |
- Audet, Joachim
(author)
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Environmental controls of plant species richness in riparian wetlands: Implications for restoration
- 2015
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In: Basic and Applied Ecology. - : Elsevier BV. - 1439-1791 .- 1618-0089. ; 16, s. 480-489
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Journal article (peer-reviewed)abstract
- Wetland restoration projects often focus on mitigating losses of nutrients (nitrogen and phosphorus) toward downstream aquatic recipients and, so far, there is no clear guidance on how to restore environmental conditions to improve biodiversity values in the restored areas. However, to provide such guidance, it is necessary to obtain a better understanding of the factors driving biodiversity in natural wetlands. For this purpose, we investigated plant community characteristics in 35 plots located at 10 Danish riparian wetlands to identify critical factors required to sustain species diversity. We hypothesized that species richness is influenced by groundwater characteristics and nutrient availability and that threshold values for these environmental variables can be defined to characterize conditions needed to sustain high diversity plant communities, We found that high groundwater level (less than 37 cm depth) and low soil phosphorus content (<347 mu g cm(-3)) were two important drivers of plant species richness. Furthermore, at high groundwater and low soil phosphorus content, low nitrogen concentration in the groundwater also favors greater species richness. Our results imply that establishment of a groundwater table close to the soil surface and low nutrient availability are important factors for improving species richness in restored areas.
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5. |
- Axelsson, Petter, et al.
(author)
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Associational resistance mediates interacting effects of herbivores and competitors on fireweed performance
- 2014
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In: Basic and Applied Ecology. - : Elsevier BV. - 1439-1791 .- 1618-0089. ; 15, s. 10-17
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Journal article (peer-reviewed)abstract
- Neighboring plants may have dual roles in relation to focal plants, being both competitors, and mediators of associational resistance (AR), or associational susceptibility (AS) to herbivores. Even though these two roles are played out simultaneously in nature, they have traditionally been studied separately. We conducted a two-by-two factorial experiment by manipulating the occurrence of neighbors (meadowsweet, Filipendula ulmaria) and shared mammal herbivores (moose, Alces alces) to investigate how the two simultaneously affect the performance of focal fireweed (Chamerion angustifolium) plants.We found that interactions between mammal herbivory and neighbors had significant effects on fireweed performance. These effects were explained by two counteracting mechanisms. First, when mammal herbivores were present, fireweed experienced AR such that plants growing outside of meadowsweet patches had an almost tripled risk of being browsed compared to plants growing among meadowsweet, resulting in reduced fireweed reproduction and growth. Second, when mammals were excluded, the association with meadowsweet had a direct negative effect on fireweed growth rates - mainly due to competition for light. Additionally, for the first time, we show that association with neighbors affected mammal-induced branching in fireweed.This study demonstrates that AR mediated by mammal herbivores can flip plant-plant interactions from competitive (-) to facilitative (+), and affect plant architecture. As AR and competition are probably simultaneously co-occurring forces, interactions between the two are likely common and thus of fundamental importance for populations and communities.
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6. |
- Ball, John, et al.
(author)
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Comparison of plant secondary metabolites and digestibility of three different boreal coniferous trees
- 2009
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In: Basic and Applied Ecology. - : Elsevier BV. - 1439-1791 .- 1618-0089. ; 10, s. 19-26
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Journal article (peer-reviewed)abstract
- Moose (Alces alces L.) prefer to browse Pinus sylvestris Over Other coniferous trees. One reason for this preference might be due to differences in the chemical composition of various coniferous plants. and/or differences in digestibility. We evaluated the in-sacco digestibility of P. sylvestris, Pinus contorta and Picea abies using a fistulated cow, (Bos taurus). Additionally. we determined the chemical profile of the different plant species (with emphasis oil specific phenolics) mid we modified the concentration of the individual phenolic (+)catechin in plant m material of P. sylvestris to test the influence Of this p particular phenolic on digestibility in vitro (IVDMD). The in-sacco experiment revealed the highest digestibility of dry matter, and neural detergent fibre for P. sylvestris. In addition, the concentration of nitrogen was significantly higher, mid the concentrations of total phenolics mid condensed tannins were significantly lower in P. sylvestris than in the Other species. Individual phenolics showed high variation but were low in P. sylvestris, where is P. contorta and P. abies at least one species-specific phenolic compound of high concentration each. We found no changes in the digestibility of samples in which we experimentally elevated (+)catechin content. (C) 2007 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.
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7. |
- Banks, John E., et al.
(author)
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Aphid parasitoids respond to vegetation heterogeneity but not to fragmentation scale: An experimental field study
- 2016
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In: Basic and Applied Ecology. - : Elsevier BV. - 1439-1791 .- 1618-0089. ; 17, s. 438-446
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Journal article (peer-reviewed)abstract
- How animal populations respond to habitat manipulations is a central theme in ecology. In recent years, the role that vegetation heterogeneity plays in regulating arthropod populations has received particular attention in both conservation science and agricultural ecology. Numerous observational studies have demonstrated that herbivores and their natural enemies are sensitive to vegetation heterogeneity, but the individual effects of percentage land cover, degree of fragmentation and patch size remain little understood. We present here the results of a manipulative field experiment that explicitly' incorporates both habitat heterogeneity and the degree to which that heterogeneity is fragmented in order to determine the effects of each factor on parasitism in an agroecosystem, We deployed combinations of broccoli (crop) and weedy vegetation (non-crop) in linear arrays that varied in their percentage devoted to crop and in the degree at which crop patches were fragmented with weeds, and recorded parasitism rates on two aphid species multiple times during two years. Parasitoids responded to the percentage of crop in plots, but not to the spatial scale at which they were fragmented. Our results suggest that vegetation heterogeneity may be more important than fragmentation scale in biological control by, parasitoids.
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8. |
- Bartomeus, Ignasi, et al.
(author)
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Pollinators, pests and soil properties interactively shape oilseed rape yield
- 2015
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In: Basic and Applied Ecology. - : Elsevier BV. - 1439-1791 .- 1618-0089. ; 16, s. 737-745
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Journal article (peer-reviewed)abstract
- Pollination, pest control, and soil properties are well known to affect agricultural production. These factors might interactively shape crop yield, but most studies focus on only one of these factors at a time. We used 15 winter oilseed rape (Brass/co napus L.) fields in Sweden to study how variation among fields in pollinator visitation rates, pollen beetle attack rates and soil properties (soil texture, pH and organic carbon) interactively determined crop yield. The fields were embedded in a landscape gradient with contrasting proportions of arable and semi-natural land. In general, pollinator visitation and pest levels were negatively correlated and varied independently of soil properties. This may reflect that above- and below-ground processes react at landscape and local spatial scales, respectively. The above-ground biotic interactions and below-ground abiotic factors interactively affected crop yield. Pollinator visitation was the strongest predictor positively associated with yield. High soil pH also benefited yield, but only at tower pest loads. Surprisingly, high pest loads increased the pollinator benefits for yield. Implementing management plans at different spatial scales can create synergies among above- and below-ground ecosystem processes, hut both scales are needed given that different processes react al different sptitial scales.
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9. |
- Beche, Dinkissa, et al.
(author)
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Prevalence of major pests and diseases in wild and cultivated coffee in Ethiopia
- 2023
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In: Basic and Applied Ecology. - 1439-1791 .- 1618-0089. ; 73, s. 3-9
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Journal article (peer-reviewed)abstract
- The study of pests and diseases on crops and crop relatives in the wild is valuable from both a theoretical and an applied point of view. Few studies have addressed multiple pests and diseases in such ecosystems. Our objectives were to (1) compare the prevalence of multiple pests and diseases on coffee in forests and more managed landscapes and (2) assess how spatial, environmental, host density and management factors affect the incidence and severity of coffee pests and diseases across forests.To achieve these objectives we studied different pests, diseases and one hyperparasite on wild and semi-wild coffee from 84 plots of 20 × 20 m across a forested landscape in southwest Ethiopia and compared the results to previous studies of more intensively managed adjacent landscapes.The prevalence of all surveyed coffee leaf pests and diseases was high (>71% of investigated plots) and very similar to the levels in more intensively managed landscapes reported in the literature. The incidence rates of all pests, diseases and the hyperparasite showed a high variation among the plots, and correlation with each other in some cases. However, this variation was weakly related to the measured environmental and management variables, but coffee pests and diseases were often positively related to high coffee density.One possible explanation for the similar prevalence is that, although the landscapes are different, the local environmental conditions have much in common since coffee is also grown under indigenous shade trees in more intensively managed landscapes. However, the variability in pest and disease levels among sites was large and it is difficult to predict where they attain high levels. There is a need of detailed investigations on drivers of spatio-temporal population dynamics of these species, including their natural enemies, to be able to provide advice for development of sustainable coffee disease management.
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10. |
- Bengtsson, Jan, et al.
(author)
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Persistent negative effects of pesticides on biodiversity and biological control potential on European farmland
- 2010
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In: Basic and Applied Ecology. - : Elsevier BV. - 1439-1791 .- 1618-0089. ; 11, s. 97-105
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Journal article (peer-reviewed)abstract
- During the last 50 years, agricultural intensification has caused many wild plant and animal species to go extinct regionally or nationally and has profoundly changed the functioning of agro-ecosystems. Agricultural intensification has many components, such as loss of landscape elements, enlarged farm and field sizes and larger inputs of fertilizer and pesticides. However, very little is known about the relative contribution of these variables to the large-scale negative effects on biodiversity. In this study, we disentangled the impacts of various components of agricultural intensification on species diversity of wild plants, carabids and ground-nesting farmland birds and on the biological control of aphids.In a Europe-wide study in eight West and East European countries, we found important negative effects of agricultural intensification on wild plant, carabid and bird species diversity and on the potential for biological pest control, as estimated from the number of aphids taken by predators. Of the 13 components of intensification we measured, use of insecticides and fungicides had consistent negative effects on biodiversity. Insecticides also reduced the biological control potential. Organic farming and other agri-environment schemes aiming to mitigate the negative effects of intensive farming on biodiversity did increase the diversity of wild plant and carabid species, but - contrary to our expectations - not the diversity of breeding birds.We conclude that despite decades of European policy to ban harmful pesticides, the negative effects of pesticides on wild plant and animal species persist, at the same time reducing the opportunities for biological pest control. If biodiversity is to be restored in Europe and opportunities are to be created for crop production utilizing biodiversity-based ecosystem services such as biological pest control, there must be a Europe-wide shift towards farming with minimal use of pesticides over large areas. (C) 2009 Gesellschaft fur Okologie. Published by Elsevier Gmbh. All rights reserved.
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