The Experts below are selected from a list of 2853 Experts worldwide ranked by ideXlab platform
Jari Haimi - One of the best experts on this subject based on the ideXlab platform.
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short term responses of soil Decomposer and plant communities to stump harvesting in boreal forests
Forest Ecology and Management, 2011Co-Authors: Saana Katajaaho, Hannu Fritze, Jari HaimiAbstract:Recently, in addition to logging residues, stumps have become an important component in energy production since there is growing global interest in the use of renewable energy sources in order to decrease anthropogenic carbon emissions. Harvesting of stumps influences the forest floor by changing vegetation and soil organic layers and exposing mineral soil across large areas. We studied whether stump harvesting after clear felling poses further short-term changes in boreal forest soil Decomposer Community (microbes and mesofauna) and vegetation when compared to the traditional site preparation practice (mounding). In general, stump harvesting caused decline in enchytraeid abundance but did not induce further major changes in Decomposer Community otherwise nor in vegetation of each soil micro-habitat (intact soil and exposed mineral soil). However, the abundances of almost all Decomposer animals were lower in the exposed mineral soil than in the intact soil. Stump removal increased the area of exposed mineral soil in the clear felled areas, leading to lower amount of high quality habitat for most Decomposer organisms. Hence, it is obvious that there are (or will be) differences in the Decomposer Community dynamics between the treatments at the forest stand level. Both species richness and coverage of plants benefitted from large-scale exposure of mineral soil. Because the stump removal procedure disturbs soil organic layers and negatively affects the Decomposer Community, it has the potential to alter nutrient dynamics in forests.
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Effects of stump removal on soil Decomposer communities in undisturbed patches of the forest floor
Scandinavian Journal of Forest Research, 2011Co-Authors: Saana Kataja-aho, Hannu Fritze, Eeva Saari, Jari HaimiAbstract:Abstract Soil preparation after clear-cutting leads to fragmentation of forest floor and, consequently, changes the habitat of Decomposers. Stump removal for bioenergy is further increasing the disturbance in the soil. We studied responses of Decomposers to stump removal in boreal spruce forests during the first 4 years after clear felling in relation to mounding. Samples for each Decomposer organism group were taken from undisturbed forest floor patches that are the main habitat for Decomposers after forest regeneration and whose amount and size obviously differ between the treatments. Microbial biomasses and Community structure, and the abundance of enchytraeids, were not found to be affected by the stump removal. The abundance of nematodes and the total numbers of collembolans were lower in the stump harvesting plots compared with the mounded plots 3 years after the regeneration. In addition, microbivorous macroarthropods had higher abundances in the mounded plots. Together, Decomposer Community in the...
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soil Decomposer Community as a model system in studying the effects of habitat fragmentation and habitat corridors
Soil Biology & Biochemistry, 2008Co-Authors: Minnaliisa Rantalainen, Hannu Fritze, Jari Haimi, Taina Pennanen, Heikki SetäläAbstract:Abstract Due to the practical difficulties of experimental study of habitat fragmentation and habitat corridors at the landscape scale, the use of smaller-scale model systems has been offered as a feasible alternative to uncover the ecological phenomena taking place in fragmented environments. In this mini-review, we consider the applicability of the soil Decomposer Community as such a model system. For the most part, this article is based on the few studies that have explicitly addressed this question by experimental manipulations of the natural habitat of soil Decomposer Community. However, to broaden the view, we also capitalize upon studies focusing on the effects of isolation and soil use changes on soil organisms and on dispersal of soil fauna, all of these being considered as factors determining the sensitivity of organisms to habitat fragmentation. Since usability of a model system by definition depends on the possibility of applying the results to other (usually larger scale) systems, we discuss the characteristics of the soil Decomposer Community also from this point of view. The existing data suggest that soil organisms, in general, are not sensitive to habitat fragmentation even in small scale. Because of this, and the unique features of the belowground environment and its biota combined with gaps in the knowledge of the life history characteristics of soil organisms, the soil Decomposer Community is not ideal for predicting the implications of habitat fragmentation and habitat corridors on threatened species. Despite this, we still believe that there are lessons to be learned by studying the effects of habitat fragmentation on this important Community of organisms, especially in combination with the consequences of ongoing climate change.
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species richness and food web structure of soil Decomposer Community as affected by the size of habitat fragment and habitat corridors
Global Change Biology, 2005Co-Authors: Minnaliisa Rantalainen, Hannu Fritze, Jari Haimi, Taina Pennanen, Heikki SetäläAbstract:While most ecologists agree that the effects of fragmentation on diversity of organisms are predominantly negative and that the scale of fragmentation defines their severity, the role of habitat corridors in mitigating those effects still remains controversial. This ambiguousness rests largely on various difficulties in experimentation, a problem partially solved in the present paper by the use of easily manipulated soil communities. In this 2.5-year-long field experiment, we investigated the responses of soil Decomposer organisms (from microbes to mesofaunal predators) to habitat fragment size, in the presence or absence of habitat corridors connecting the fragments. The habitat fragments and corridors, composed of forest humus soil, were embedded in mineral soil representing an uninhabitable (or nonpreferred) matrix for the Decomposer organisms. The results demonstrate that soil Decomposer organisms do respond to changes in their habitat size: the species richness of microarthropods (mites and collembolans) increased as the size of the fragments increased. Especially collembolan species and predatory mites proved to be sensitive to the restricted habitat size, which is suggested to be a consequence of the large proportion of rare species and small and fluctuating population sizes in these groups. Contrary to our expectations, the presence of corridors had no positive effects on species richness or abundance of any of the studied faunas, possibly because of the low quality of the corridors. On the other hand, the biomass of soil fungi increased in the presence of corridors, which apparently provided a preferred pathway for vegetative dispersal of the fungi. Our results indicate that despite their characteristic underground environment, the response of soil Decomposer organisms ‐ in particular that of microarthropods ‐ to habitat size is not unlike to that of the larger organisms in aboveground habitats.
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Influence of resource quality on the composition of soil Decomposer Community in fragmented and continuous habitat
Soil Biology and Biochemistry, 2004Co-Authors: Minnaliisa Rantalainen, Hannu Fritze, Jari Haimi, Leena Kontiola, Heikki SetäläAbstract:Abstract The aim of this field experiment was to explore the combined effects of two factors potentially affecting the local composition of soil Decomposer Community: resource quality and habitat fragmentation. We created humus (habitat) patches with three different resource quality: (1) pure homogenised humus; (2) humus enriched with needle litter; and (3) humus enriched with needle and leaf litter. These patches were embedded either in a mineral soil matrix, thus representing fragmented habitat, or in natural forest soil, representing continuous (non-fragmented) habitat. The development of faunal (colonisations/extinctions of soil animal populations) and microbial communities in the patches was followed for 12 months. Our results partly supported the hypothesized strong influence of resource quality on the structure of local soil food webs: the abundances of practically all groups of soil fauna, together with biomass of fungi, were higher in the litter-enriched patches than in the pure humus patches. The manifestation and magnitude of the responses of fauna were, however, strongly affected by complex interactions between the characteristics (especially colonisation capacity) of the faunal group in question, habitat quality and time of sampling. In microarthropods and nematodes, the effect of resource quality cascaded up to the predatory level, rendering further support to the existence of strong bottom-up control in soil food webs. Contrary to our expectations, species richness of the communities was not unanimously affected by resource quality. Habitat fragmentation affected the communities only through different number and identity of patch-colonising species in the fragmented and continuous habitat: fragmentation induced no extinctions of species during the experiment at any resource quality level. Consequently, the results indicate that resource quality is more important factor than habitat fragmentation in determining the local structure of communities in soils. On the other hand, colonisation capacities of soil organisms appear to set limits to the exploitation of local resources.
Heikki Setälä - One of the best experts on this subject based on the ideXlab platform.
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soil Decomposer Community as a model system in studying the effects of habitat fragmentation and habitat corridors
Soil Biology & Biochemistry, 2008Co-Authors: Minnaliisa Rantalainen, Hannu Fritze, Jari Haimi, Taina Pennanen, Heikki SetäläAbstract:Abstract Due to the practical difficulties of experimental study of habitat fragmentation and habitat corridors at the landscape scale, the use of smaller-scale model systems has been offered as a feasible alternative to uncover the ecological phenomena taking place in fragmented environments. In this mini-review, we consider the applicability of the soil Decomposer Community as such a model system. For the most part, this article is based on the few studies that have explicitly addressed this question by experimental manipulations of the natural habitat of soil Decomposer Community. However, to broaden the view, we also capitalize upon studies focusing on the effects of isolation and soil use changes on soil organisms and on dispersal of soil fauna, all of these being considered as factors determining the sensitivity of organisms to habitat fragmentation. Since usability of a model system by definition depends on the possibility of applying the results to other (usually larger scale) systems, we discuss the characteristics of the soil Decomposer Community also from this point of view. The existing data suggest that soil organisms, in general, are not sensitive to habitat fragmentation even in small scale. Because of this, and the unique features of the belowground environment and its biota combined with gaps in the knowledge of the life history characteristics of soil organisms, the soil Decomposer Community is not ideal for predicting the implications of habitat fragmentation and habitat corridors on threatened species. Despite this, we still believe that there are lessons to be learned by studying the effects of habitat fragmentation on this important Community of organisms, especially in combination with the consequences of ongoing climate change.
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species richness and food web structure of soil Decomposer Community as affected by the size of habitat fragment and habitat corridors
Global Change Biology, 2005Co-Authors: Minnaliisa Rantalainen, Hannu Fritze, Jari Haimi, Taina Pennanen, Heikki SetäläAbstract:While most ecologists agree that the effects of fragmentation on diversity of organisms are predominantly negative and that the scale of fragmentation defines their severity, the role of habitat corridors in mitigating those effects still remains controversial. This ambiguousness rests largely on various difficulties in experimentation, a problem partially solved in the present paper by the use of easily manipulated soil communities. In this 2.5-year-long field experiment, we investigated the responses of soil Decomposer organisms (from microbes to mesofaunal predators) to habitat fragment size, in the presence or absence of habitat corridors connecting the fragments. The habitat fragments and corridors, composed of forest humus soil, were embedded in mineral soil representing an uninhabitable (or nonpreferred) matrix for the Decomposer organisms. The results demonstrate that soil Decomposer organisms do respond to changes in their habitat size: the species richness of microarthropods (mites and collembolans) increased as the size of the fragments increased. Especially collembolan species and predatory mites proved to be sensitive to the restricted habitat size, which is suggested to be a consequence of the large proportion of rare species and small and fluctuating population sizes in these groups. Contrary to our expectations, the presence of corridors had no positive effects on species richness or abundance of any of the studied faunas, possibly because of the low quality of the corridors. On the other hand, the biomass of soil fungi increased in the presence of corridors, which apparently provided a preferred pathway for vegetative dispersal of the fungi. Our results indicate that despite their characteristic underground environment, the response of soil Decomposer organisms ‐ in particular that of microarthropods ‐ to habitat size is not unlike to that of the larger organisms in aboveground habitats.
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Influence of resource quality on the composition of soil Decomposer Community in fragmented and continuous habitat
Soil Biology and Biochemistry, 2004Co-Authors: Minnaliisa Rantalainen, Hannu Fritze, Jari Haimi, Leena Kontiola, Heikki SetäläAbstract:Abstract The aim of this field experiment was to explore the combined effects of two factors potentially affecting the local composition of soil Decomposer Community: resource quality and habitat fragmentation. We created humus (habitat) patches with three different resource quality: (1) pure homogenised humus; (2) humus enriched with needle litter; and (3) humus enriched with needle and leaf litter. These patches were embedded either in a mineral soil matrix, thus representing fragmented habitat, or in natural forest soil, representing continuous (non-fragmented) habitat. The development of faunal (colonisations/extinctions of soil animal populations) and microbial communities in the patches was followed for 12 months. Our results partly supported the hypothesized strong influence of resource quality on the structure of local soil food webs: the abundances of practically all groups of soil fauna, together with biomass of fungi, were higher in the litter-enriched patches than in the pure humus patches. The manifestation and magnitude of the responses of fauna were, however, strongly affected by complex interactions between the characteristics (especially colonisation capacity) of the faunal group in question, habitat quality and time of sampling. In microarthropods and nematodes, the effect of resource quality cascaded up to the predatory level, rendering further support to the existence of strong bottom-up control in soil food webs. Contrary to our expectations, species richness of the communities was not unanimously affected by resource quality. Habitat fragmentation affected the communities only through different number and identity of patch-colonising species in the fragmented and continuous habitat: fragmentation induced no extinctions of species during the experiment at any resource quality level. Consequently, the results indicate that resource quality is more important factor than habitat fragmentation in determining the local structure of communities in soils. On the other hand, colonisation capacities of soil organisms appear to set limits to the exploitation of local resources.
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composition and trophic structure of detrital food web in ant nest mounds of formica aquilonia and in the surrounding forest soil
Oikos, 1998Co-Authors: Jouni Laakso, Heikki SetäläAbstract:Community composition and food web structure of soil Decomposer biota in relation to various habitat properties were compared between upper parts of red wood ant (Formica aquilonia) nest mounds and the adjacent forest soil. For a description of trophic structure of the Decomposer Community in the two habitats, soil Decomposers were classified into 14 trophic groups. Classification of the taxa into three habitat preference categories resulted in a clear division of the fauna into either soil or nest specialists, relatively few taxa falling between these two groups. A large majority of the nest specialists belonged to a non-myrmecophilous soil Decomposer fauna so far largely overlooked in studies on ant-invertebrate associations. Trophic organisation of the nest mound Community differed clearly from that in the soil by having considerably larger biomass at the base of the food web, and less large predators -other than ants - at the top of the web. Contrary to forest soils. the clear dominance of bacterial feeding microfauna over the fungal feeding microfauna in the nest mounds suggests that most of the energy passing through the food web is channelled through a bacterial-based food-web compartment in the nest mounds. Relatively constant temperature and moisture in the nest surface, continuous energy input by the ants to the nests, and ant-induced reduction in predation pressure on macropredators are suggested to be responsible for the development of the typical Decomposer Community structure in the nest mounds. Thus, the food-web dynamics in ant nest mounds represent an interesting case in which the behaviour of an invertebrate species (i.e. the ant) has a potential to control the development of a system-level organisation. The high biomass of microbi-detritivorous animals, especially earthworms, in the nest mounds suggests that the activities of the Decomposer fauna may feed back to the structure of nest mound and indirectly alter the performance of the ant colony.
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Regulation of Decomposer Community structure and decomposition processes in herbicide stressed humus soil
Applied Soil Ecology, 1997Co-Authors: Janne Salminen, Heikki Setälä, Jari HaimiAbstract:Abstract Regulation of soil Decomposer Community structure and ecosystem processes, such as nutrient cycling, under herbicide stress was studied in a microcosm experiment. For the experiment, coniferous forest soil was defaunated and put into the microcosms. In the microcosms two different food webs including microbes, nematodes, tardigrades and oribatid mites, either with or without predatory mesostigmatid mites, were reconstructed. Half of the microcosms were stressed with a herbicide (active ingredient was terbuthylazine). During the 57 weeks incubation Community structure of Decomposers and nitrogen mineralisation were studied at five destructive samplings and two water irrigations. Soil respiration was measured weekly starting at week 26. Mesostigmatid mites regulated densities of some prey species and hence they had an effect on the Community structure of microbivores. A trophic cascade from predators to microbes took place both in unstressed and stressed soils: microbial activity decreased in the presence of predators. Predation effect was observed more clearly in the unstressed soil although predators maintained their populations longer in the herbicide stressed soil. Predators had no significant effects on N mineralisation while herbicide increased it. Oribatids were reduced by the herbicide at the later phase of the experiment. It can be concluded that Decomposer food webs and decomposition in the soil can partly be top-down controlled. Due to a high degree of omnivory it was impossible to determine precisely the trophic structure of the food web. Herbicide contamination altered the Community regulation and ecosystem processes via direct toxicity and by affecting trophic interactions. Although the application of food web analysis in risk assessment procedures has been proved to be problematic, there is a clear need for system level studies because of the chemical-induced indirect effects on the food webs.
Hannu Fritze - One of the best experts on this subject based on the ideXlab platform.
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short term responses of soil Decomposer and plant communities to stump harvesting in boreal forests
Forest Ecology and Management, 2011Co-Authors: Saana Katajaaho, Hannu Fritze, Jari HaimiAbstract:Recently, in addition to logging residues, stumps have become an important component in energy production since there is growing global interest in the use of renewable energy sources in order to decrease anthropogenic carbon emissions. Harvesting of stumps influences the forest floor by changing vegetation and soil organic layers and exposing mineral soil across large areas. We studied whether stump harvesting after clear felling poses further short-term changes in boreal forest soil Decomposer Community (microbes and mesofauna) and vegetation when compared to the traditional site preparation practice (mounding). In general, stump harvesting caused decline in enchytraeid abundance but did not induce further major changes in Decomposer Community otherwise nor in vegetation of each soil micro-habitat (intact soil and exposed mineral soil). However, the abundances of almost all Decomposer animals were lower in the exposed mineral soil than in the intact soil. Stump removal increased the area of exposed mineral soil in the clear felled areas, leading to lower amount of high quality habitat for most Decomposer organisms. Hence, it is obvious that there are (or will be) differences in the Decomposer Community dynamics between the treatments at the forest stand level. Both species richness and coverage of plants benefitted from large-scale exposure of mineral soil. Because the stump removal procedure disturbs soil organic layers and negatively affects the Decomposer Community, it has the potential to alter nutrient dynamics in forests.
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Effects of stump removal on soil Decomposer communities in undisturbed patches of the forest floor
Scandinavian Journal of Forest Research, 2011Co-Authors: Saana Kataja-aho, Hannu Fritze, Eeva Saari, Jari HaimiAbstract:Abstract Soil preparation after clear-cutting leads to fragmentation of forest floor and, consequently, changes the habitat of Decomposers. Stump removal for bioenergy is further increasing the disturbance in the soil. We studied responses of Decomposers to stump removal in boreal spruce forests during the first 4 years after clear felling in relation to mounding. Samples for each Decomposer organism group were taken from undisturbed forest floor patches that are the main habitat for Decomposers after forest regeneration and whose amount and size obviously differ between the treatments. Microbial biomasses and Community structure, and the abundance of enchytraeids, were not found to be affected by the stump removal. The abundance of nematodes and the total numbers of collembolans were lower in the stump harvesting plots compared with the mounded plots 3 years after the regeneration. In addition, microbivorous macroarthropods had higher abundances in the mounded plots. Together, Decomposer Community in the...
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soil Decomposer Community as a model system in studying the effects of habitat fragmentation and habitat corridors
Soil Biology & Biochemistry, 2008Co-Authors: Minnaliisa Rantalainen, Hannu Fritze, Jari Haimi, Taina Pennanen, Heikki SetäläAbstract:Abstract Due to the practical difficulties of experimental study of habitat fragmentation and habitat corridors at the landscape scale, the use of smaller-scale model systems has been offered as a feasible alternative to uncover the ecological phenomena taking place in fragmented environments. In this mini-review, we consider the applicability of the soil Decomposer Community as such a model system. For the most part, this article is based on the few studies that have explicitly addressed this question by experimental manipulations of the natural habitat of soil Decomposer Community. However, to broaden the view, we also capitalize upon studies focusing on the effects of isolation and soil use changes on soil organisms and on dispersal of soil fauna, all of these being considered as factors determining the sensitivity of organisms to habitat fragmentation. Since usability of a model system by definition depends on the possibility of applying the results to other (usually larger scale) systems, we discuss the characteristics of the soil Decomposer Community also from this point of view. The existing data suggest that soil organisms, in general, are not sensitive to habitat fragmentation even in small scale. Because of this, and the unique features of the belowground environment and its biota combined with gaps in the knowledge of the life history characteristics of soil organisms, the soil Decomposer Community is not ideal for predicting the implications of habitat fragmentation and habitat corridors on threatened species. Despite this, we still believe that there are lessons to be learned by studying the effects of habitat fragmentation on this important Community of organisms, especially in combination with the consequences of ongoing climate change.
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species richness and food web structure of soil Decomposer Community as affected by the size of habitat fragment and habitat corridors
Global Change Biology, 2005Co-Authors: Minnaliisa Rantalainen, Hannu Fritze, Jari Haimi, Taina Pennanen, Heikki SetäläAbstract:While most ecologists agree that the effects of fragmentation on diversity of organisms are predominantly negative and that the scale of fragmentation defines their severity, the role of habitat corridors in mitigating those effects still remains controversial. This ambiguousness rests largely on various difficulties in experimentation, a problem partially solved in the present paper by the use of easily manipulated soil communities. In this 2.5-year-long field experiment, we investigated the responses of soil Decomposer organisms (from microbes to mesofaunal predators) to habitat fragment size, in the presence or absence of habitat corridors connecting the fragments. The habitat fragments and corridors, composed of forest humus soil, were embedded in mineral soil representing an uninhabitable (or nonpreferred) matrix for the Decomposer organisms. The results demonstrate that soil Decomposer organisms do respond to changes in their habitat size: the species richness of microarthropods (mites and collembolans) increased as the size of the fragments increased. Especially collembolan species and predatory mites proved to be sensitive to the restricted habitat size, which is suggested to be a consequence of the large proportion of rare species and small and fluctuating population sizes in these groups. Contrary to our expectations, the presence of corridors had no positive effects on species richness or abundance of any of the studied faunas, possibly because of the low quality of the corridors. On the other hand, the biomass of soil fungi increased in the presence of corridors, which apparently provided a preferred pathway for vegetative dispersal of the fungi. Our results indicate that despite their characteristic underground environment, the response of soil Decomposer organisms ‐ in particular that of microarthropods ‐ to habitat size is not unlike to that of the larger organisms in aboveground habitats.
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Influence of resource quality on the composition of soil Decomposer Community in fragmented and continuous habitat
Soil Biology and Biochemistry, 2004Co-Authors: Minnaliisa Rantalainen, Hannu Fritze, Jari Haimi, Leena Kontiola, Heikki SetäläAbstract:Abstract The aim of this field experiment was to explore the combined effects of two factors potentially affecting the local composition of soil Decomposer Community: resource quality and habitat fragmentation. We created humus (habitat) patches with three different resource quality: (1) pure homogenised humus; (2) humus enriched with needle litter; and (3) humus enriched with needle and leaf litter. These patches were embedded either in a mineral soil matrix, thus representing fragmented habitat, or in natural forest soil, representing continuous (non-fragmented) habitat. The development of faunal (colonisations/extinctions of soil animal populations) and microbial communities in the patches was followed for 12 months. Our results partly supported the hypothesized strong influence of resource quality on the structure of local soil food webs: the abundances of practically all groups of soil fauna, together with biomass of fungi, were higher in the litter-enriched patches than in the pure humus patches. The manifestation and magnitude of the responses of fauna were, however, strongly affected by complex interactions between the characteristics (especially colonisation capacity) of the faunal group in question, habitat quality and time of sampling. In microarthropods and nematodes, the effect of resource quality cascaded up to the predatory level, rendering further support to the existence of strong bottom-up control in soil food webs. Contrary to our expectations, species richness of the communities was not unanimously affected by resource quality. Habitat fragmentation affected the communities only through different number and identity of patch-colonising species in the fragmented and continuous habitat: fragmentation induced no extinctions of species during the experiment at any resource quality level. Consequently, the results indicate that resource quality is more important factor than habitat fragmentation in determining the local structure of communities in soils. On the other hand, colonisation capacities of soil organisms appear to set limits to the exploitation of local resources.
Stefan Scheu - One of the best experts on this subject based on the ideXlab platform.
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micro Decomposer communities and decomposition processes in tropical lowlands as affected by land use and litter type
Oecologia, 2018Co-Authors: Valentyna Krashevska, Elena Malysheva, Bernhard Klarner, Yuri A Mazei, Mark Maraun, Rahayu Widyastuti, Stefan ScheuAbstract:: We investigated how the land-use change from rainforest into jungle rubber, intensive rubber and oil palm plantations affects Decomposers and litter decomposition in Sumatra, Indonesia. Litterbags containing three litter types were placed into four land-use systems and harvested after 6 and 12 months. Litter mass loss and litter element concentrations were measured, and different microbial groups including bacteria, fungi and testate amoebae were studied. After 12 months 81, 65, 63 and 53% of litter exposed in rainforest, jungle rubber in oil palm and rubber plantations was decomposed. In addition to land use, litter decomposition varied strongly with litter type and short-term effects differed markedly from long-term effects. After 6 months, oil palm and rubber litter decomposed faster than rainforest litter, but after 12 months, decomposition of rainforest litter exceeded that of oil palm and rubber litter, reflecting adaptation of bacteria and fungi to decompose structural compounds in rainforest litter but not (or less) in rubber and oil palm litter. Bacterial and fungal Community composition and testate amoeba species number and density varied strongly with litter type, but little with land use. However, Community composition of testate amoebae was mainly affected by land use. Generally, changes in bacteria, fungi and testate amoebae were linked to changes in litter element concentrations, suggesting that element ratios of litter material as basal resource for the Decomposer food web shape the structure of Decomposer communities and decomposition processes via bottom-up forces. Overall, changing rainforest to monoculture plantations shifts the Decomposer Community structure and negatively affects litter decomposition.
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Effects of Collembola on root properties of two competing ruderal plant species
Soil Biology & Biochemistry, 2006Co-Authors: Kerstin Endlweber, Stefan ScheuAbstract:Plant roots compete for nutrients mineralised by the Decomposer Community in soil. By affecting microbial biomass and activity Collembola influence the nutrient availability to plants. We investigated the effect of Collembola (Protaphorura fimata Gisin) on growth and competition between of two plant species, Cirsium arvense L (creeping thistle) and Epilobium adnatum Griseb. (square-stemmed willow herb), in a laboratory experiment. Two seedlings of each plant species were planted in rhizotrons either in combination or in monoculture (intra- and interspecific competition). Interspecific competition strongly reduced total biomass of C. arvense whereas E. adnatum suffered most from intraspecific competition. Collembola neither affected the competitive relationship of the two plant species nor shoot and root biomass. Although Collembola did not affect total root biomass they influenced root morphology of both plant species. Roots grew longer and thinner and had more root tips in presence of Collembola. Root elongation is generally ascribed to the exploitation of nutrient rich patches in soil. We hypothesise that changes in root morphology in presence of Collembola are due to Collembola-mediated changes in nutrient availability and distribution.
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abundance and trophic structure of macro Decomposers on alpine pastureland central alps tyrol effects of abandonment of pasturing
Pedobiologia, 2005Co-Authors: Julia Seeber, Gilg U H Seeber, Wolfgang Kossler, Reinhard Langel, Stefan Scheu, Erwin MeyerAbstract:Summary On four differently managed and abandoned alpine meadows and pastures densities, biomasses and 15 N signatures of the macrofauna were assessed to evaluate the structural and functional changes of the Decomposer food webs. The composition of the macrofauna Decomposer Community changes remarkably after the abandonment of alpine meadows and pastures. Lumbricus rubellus functions as key primary Decomposer on alpine meadows and pastures whereas on abandoned sites other primary Decomposers including Dendrobaena octaedra , Cylindroiulus meinerti , C. fulviceps and diptera larvae become more important. Decomposer species, such as Enantiulus nanus, presumably function as both primary and secondary Decomposers and endogeic earthworms, such as Octolasion lacteum and Aporrectodea rosea , uniformly function as secondary Decomposers. Abandonment of pasturing causes a shift in the composition of the macrofauna and the newly established fauna is unable to process and translocate the litter materials produced by the plants of the abondoned sites.
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Decomposer animals lumbricidae collembola and organic matter distribution affect the performance of lolium perenne poaceae and trifolium repens fabaceae
Soil Biology & Biochemistry, 2004Co-Authors: Knut Kreuzer, Reinhard Langel, Michael Bonkowski, Stefan ScheuAbstract:Abstract Decomposer animals stimulate plant growth by indirect effects such as increasing nutrient availability or by modifying microbial communities in the rhizosphere. In grasslands, the spatial distribution of organic matter (OM) rich in nutrients depends on agricultural practice and the bioturbation activities of large detritivores, such as earthworms. We hypothesized that plants of different functional groups with contrasting nutrient uptake and resource allocation strategies differentially benefit from sites in soil with OM accumulation and the presence of Decomposer animals. In a greenhouse experiment we investigated effects of spatial distribution of 15 N-labelled grass litter, earthworms and collembola on a simple grassland Community consisting of Lolium perenne (grass) and Trifolium repens (legume). Litter aggregates (compared to homogeneous litter distribution) increased total shoot biomass, root biomass and 15 N uptake by the plants. Earthworms and collembola did not affect total N uptake of T. repens ; however, the presence of both increased 15 N uptake by T. repens and L. perenne . Earthworms increased shoot biomass of T. repens 1.11-fold and that of L. perenne 2.50 fold. Biomass of L. perenne was at a maximum in the presence of earthworms, collembola and with litter concentrated in a single aggregate. Shoot biomass of T. repens increased in the presence of collembola, with L. perenne generally responding opposingly. The results indicate that the composition of the Decomposer Community and the distribution of OM in soil affect plant competition and therefore plant Community composition.
Mark A Bradford - One of the best experts on this subject based on the ideXlab platform.
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climate masks Decomposer influence in a cross site litter decomposition study
Soil Biology & Biochemistry, 2017Co-Authors: Ashley D Keiser, Mark A BradfordAbstract:Leaf litter is a significant input of carbon and nutrients to forested systems. Rates of foliar decomposition, and cycling of carbon and nutrients, appear consistently explained by climate and litter quality. Although the soil Decomposer Community actually mineralizes litter, its independent role is often undetected in cross-site studies. At three sites along an elevational gradient in eastern U.S. temperate forest, we used a reciprocal litter transplant design to explore whether climate masks the functional influence of the Decomposer Community on litter decomposition dynamics in the short- and longer-term. Climate, measured as the climate decomposition index, best predicted mass loss in the longer term, over 23 and 31 months (the maximum incubation period). However, Decomposer Community function also predicted mass loss dynamics across the same time period. Therefore, climate effects on mass loss correlated positively with differences in the functional ability of the three soil Decomposer communities. Our findings suggest that climate ‘masks’ the independent influence of the soil Decomposer Community over litter mass loss dynamics, because direct positive effects of more favorable climate on decomposition rates appear correlated with greater functional potential of the Decomposer communities. These results fit within existing theory and experimental evidence that soil microorganisms both adapt to their climate regime, and are directly, through biotic activity, and indirectly, via Community structure or function, affected by climate. These non-linear effects of climate may then amplify Decomposer function in warm environments and suppress function in cool environments. Hence, our results suggest that decomposition relationships observed across spatial gradients may fail to adequately represent how decomposition will respond to changing climate across time.
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Climate history shapes contemporary leaf litter decomposition
Biogeochemistry, 2015Co-Authors: Michael S. Strickland, Ashley D Keiser, Mark A BradfordAbstract:Litter decomposition is mediated by multiple variables, of which climate is expected to be a dominant factor at global scales. However, like other organisms, traits of Decomposers and their communities are shaped not just by the contemporary climate but also their climate history. Whether or not this affects decomposition rates is underexplored. Here we source Decomposer communities from three forest sites contrasting in climate (tropical, temperate, boreal), and, using experimental microcosms, quantify decomposition of a common litter under a factorial combination of four temperature (15, 20, 25, and 30 °C) and five moisture regimes (35, 55, 70, 85, and 100 % water holding capacity). We find that the climate history of the Decomposer Community is an important determinant of litter decomposition, explaining the same amount of variance in decomposition as both temperature and moisture. Further, climate history also shapes the effect of contemporary climate (i.e. experimental) on decomposition, both in terms of the magnitude of decomposition under optimal conditions and the range of abiotic conditions at which high decomposition rates are maintained. For example, at optimal conditions (i.e. 25 °C/70 % WHC) the tropical site has a greater decomposition rate than the other two sites. However, the temperate and boreal sites have greater ‘niche breadth’, where decomposition rates are more sustained (i.e. decrease less) as temperature and moisture deviate further from the optimum. Our data suggest that climate history shapes the functional response of the soil Decomposer Community, as it does for animals and plants. Yet how this shaping affects decomposition rates across regional and global climate gradients, and how such relationships are applied to temporal predictions, remain unanswered questions.
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disentangling the mechanisms underlying functional differences among Decomposer communities
Journal of Ecology, 2014Co-Authors: Ashley D Keiser, Michael S. Strickland, David A Keiser, Mark A BradfordAbstract:Summary 1. Home-field advantage (HFA) is a commonly used sports analogy, which has seen recent growth within the ecosystem ecology literature. It is most often invoked in litter transplant studies, where local adaptation (HFA) explains higher decomposition rates of leaf litter on ‘home’ soil communities. 2. In exploring the mechanisms driving functional differences among soil Decomposer communities, a consistent quantitative framework is lacking. 3. We review methods for calculating HFA, propose a consolidated regression approach and demonstrate why HFA must be calculated along with a new ‘ability’ metric if we are to test definitively the competing hypotheses that soil Decomposer communities are functionally equivalent versus dissimilar. We demonstrate that qualitative interpretations of HFA differ when the ability of a Decomposer Community is calculated simultaneously with HFA. For example, communities may differ in their ability to degrade litter in the absence of HFA, or apparent HFA may instead be caused by differing abilities, changing our ecological interpretation of the factors generating functional differences among Decomposer communities. 4. Synthesis: We propose a single, statistical approach to help evaluate how and why soil Decomposer communities differ in functional abilities. Our approach should help formalize mechanistic interpretations of why soil Community composition commonly influences litter decomposition rates.
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linkages between below and aboveground communities Decomposer responses to simulated tree species loss are largely additive
Soil Biology & Biochemistry, 2009Co-Authors: Beclcy A Ball, Mark A Bradford, D C Coleman, Mark D HunterAbstract:Inputs of aboveground plant litter influence the abundance and activities of belowground Decomposer biota. Litter-mixing studies have examined whether the diversity and heterogeneity of litter inputs affect Decomposer communities in ways that can be predicted from monocultures. They have mainly attempted to detect non-additive effects of litter mixing, although individual species effects (additivity) as well as species interactions (non-additivity) may alter decomposition rates. To determine potential impacts of plant species loss on aboveground-Decomposer linkages, we assessed both additive and non-additive effects of litter mixing on Decomposer communities. A full-factorial litterbag experiment with leaves from four deciduous tree species was conducted, to assess responses of bacteria, fungi, nematodes, and microarthropods. Data were analyzed using a statistical method that first looked for additive effects based on the presence or absence of species and then any significant species interactions. We observed almost exclusively additive effects of all four litter species on Decomposer biota, with each species exerting effects on different aspects of the Community. These results imply that the consequences of species loss for the Decomposer Community will be largely predictable from knowledge of single species litter dynamics. The two species at opposite ends of the quality spectrum exerted the most effects. High-quality Liriodendron tulipifera supported a more diverse arthropod Community and drove bottom-up effects on the Decomposer food web. Low-quality Rhododendron maximum had negative effects on most groups of biota. Litter of mid-quality species exerted fewer effects. The influence of litter species richness on the Tylenchidae (nematodes) was the only non-additive effect of litter mixing. Together, these data demonstrate an effect of plant Community composition on Decomposer biomass, abundance, and diversity, confirming a link between above and belowground communities. We were able to identify the species to which the Decomposer Community is most sensitive, aiding predictions of the consequences of the loss of these dominant species on the Decomposer Community, with potential feedbacks for organic matter and nutrient turnover.
