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Wenju Liang - One of the best experts on this subject based on the ideXlab platform.
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ecosystem services of the soil food web after long term application of agricultural management practices
Soil Biology & Biochemistry, 2017Co-Authors: Jeffrey P Mitchell, H Ferris, Xiaoke Zhang, Wenju LiangAbstract:Abstract The structure of soil nematode assemblages was assessed in field plots in the San Joaquin Valley of California which have 16-year management system histories. Attributes of the ecosystem functions of the assemblages were determined in laboratory studies. The four agricultural management systems were no tillage (minimum tillage) with cover crops in the intervals between economic crops, standard tillage with cover crops, minimum tillage without cover crops and standard tillage without cover crops. The economic crops were sorghum and garbanzo beans. A soil column system was used in laboratory studies to evaluate the nitrogen mineralization ecosystem service associated with nematode assemblages in soils from the four management systems compared to that in defaunated soil. In an additional comparison, defaunated soil was amended with mineral fertilizer solution for comparison with the mineralization service of the soil fauna. Management systems using cover crops, which created a continuity of both photosynthetic production and roots in the soil, strongly enhanced the nematode assemblages in the field soil. Management systems with cover crops had greater total abundance, measured as numbers, biomass and metabolic footprints, of nematodes, and also of the functional guilds of nematodes considered important in soil fertility and as prey for predators. Leachates from soil columns with intact nematode assemblages had greater total mineral nitrogen and supported greater plant growth than those from defaunated columns. Soil carbon levels in field plots were strongly affected by the management systems. The biomass and diversity-weighted footprint of bacterivore and microbivore (Bacterivores plus fungivores) nematodes, in turn, were correlated with levels of soil carbon.
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Interactive effects of elevated ozone and UV-B radiation on soil nematode diversity
Ecotoxicology (London England), 2013Co-Authors: Xuelian Bao, Jian-feng Hua, Tianhong Zhao, Wenju LiangAbstract:Ultraviolet-B (UV-B) radiation and elevated tropospheric ozone may cause reductions in the productivity and quality of important agricultural crops. However, research regarding their interactive effect is still scarce, especially on the belowground processes. Using the open top chambers experimental setup, we monitored the response of soil nematodes to the elevated O3 and UV-B radiation individually as well as in combination. Our results indicated that elevated O3 and UV-B radiation have impact not only on the belowground biomass of plants, but also on the community structure and functional diversity of soil nematodes. The canonical correspondence analysis suggested that soil pH, shoot biomass and microbial biomass C and N were relevant parameters that influencing soil nematode distribution. The interactive effects of elevated O3 and UV-B radiation was only observed on the abundance of Bacterivores. UV-B radiation significantly increased the abundance of total nematodes and Bacterivores in comparison with the control at pod-filling stage of soybean. Following elevated O3, nematode diversity index decreased and dominance index increased relative to the control at pod-filling stage of soybean. Nematode functional diversity showed response to the effects of elevated O3 and UV-B radiation at pod-bearing stage. Higher enrichment index and lower structure index in the treatment with both elevated O3 and UV-B radiation indicated a stressed soil condition and degraded soil food web. However, the ratios of nematode trophic groups suggested that the negative effects of elevated O3 on soil food web may be weakened by the UV-B radiations.
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The abundances of total nematodes and trophic groups among different water or/and N addition treatments.
2013Co-Authors: Xiaoming Sun, Xiaoke Zhang, Shixiu Zhang, Guanhua Dai, Shijie Han, Wenju LiangAbstract:Bars indicate standard errors. OP, omnivores-predators; PP, plant-parasites; FF, fungivores; BF, Bacterivores.
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soil microbial food web responses to free air ozone enrichment can depend on the ozone tolerance of wheat cultivars
Soil Biology & Biochemistry, 2012Co-Authors: Qi Li, Xiaoke Zhang, Caiyan Lu, Yong Jiang, Wenju LiangAbstract:Soil processes are driven by soil organisms and their interactions with plants and soil abiotic conditions. Climate changes may directly or indirectly alter soil processes and the organisms mediating these processes. Although aboveground influences of ozone have been studied widely on agroecosystems, the effects on belowground processes are poorly understood. This study aimed to investigate the effects of elevated ozone concentration [O3] on the components of soil microbial food webs and compare their responses between ozone-sensitive and ozone-tolerant wheat cultivars. The responses of soil biota to elevated [O3] varied between the two wheat cultivars. Fungal PLFA and the fungi to bacteria ratio decreased following elevated [O3], especially in the rhizospheric soil of ozone-tolerant wheat. Nematode functional guilds were sensitive to elevated [O3] and cultivar effects. At wheat jointing stage, Bacterivores belonging to K-strategies decreased following elevated [O3], while fungivores exhibited a reverse trend. The abundance of flagellates decreased in ozone-tolerant wheat, but increased in ozone-sensitive wheat following elevated [O3]. However, an opposite trend was found in the Bacterivores belonging to r-strategies. In conclusion, wheat cultivars play an important role in determining the effects of elevated [O3] on soil food web. The responses of soil biota to elevated [O3] were greater in ozone-tolerant wheat than in ozone-sensitive wheat, which may in turn have influenced soil organic matter decomposition and nutrient turnover.
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nematode faunal response to long term application of nitrogen fertilizer and organic manure in northeast china
Soil Biology & Biochemistry, 2009Co-Authors: Wenju Liang, Xiaoke Zhang, Yilai Lou, Shuang Zhong, Jingkuan WangAbstract:Nematode faunal response to the long-term (20-year) application of nitrogen fertilizer and organic manure was monitored in a Hapli-Udic Cambosol of Northeast China, where no fertilizer (C), nitrogen fertilizer (N), organic manure (M) and nitrogen fertilizer plus organic manure (N + M) treatments were compared. The obtained results showed that total nematode abundance responded positively to the M and N + M treatments. The numbers of Acrobeloides increased in the M and N + M treatments at maize jointing and booting stages, and those of Aphelenchoides were higher in the N + M treatment than in the N treatment at maize ripening stage. Early in the growing season, the numbers of Bacterivores of cp-1 (cp, colonizer-persister) and cp-2 guilds were higher in the M and N + M treatments than in the N treatment, while those of Bacterivores and fungivores of cp-4 guilds were higher in the C treatment than in the N, M and N + M treatments. Except at maize seedling stage, the numbers of fungivores of cp-2 and herbivores of cp-3 guilds were higher in the N + M treatment than in the C treatment. Ratios of the weighted abundance of representatives of specific functional guilds were used as indicators of food web structure, enrichment and decomposition channels. Values of the enrichment index (EI) at maize seedling and jointing stages were higher in the M and N + M treatments than in the C and N treatments, while an opposite trend was observed in the channel index (CI). Higher El and lower Cl suggest an enriched soil food web dominated with bacterial decomposition channels in the M and N+M treatments. (C) 2008 Elsevier Ltd. All rights reserved.
H Ferris - One of the best experts on this subject based on the ideXlab platform.
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ecosystem services of the soil food web after long term application of agricultural management practices
Soil Biology & Biochemistry, 2017Co-Authors: Jeffrey P Mitchell, H Ferris, Xiaoke Zhang, Wenju LiangAbstract:Abstract The structure of soil nematode assemblages was assessed in field plots in the San Joaquin Valley of California which have 16-year management system histories. Attributes of the ecosystem functions of the assemblages were determined in laboratory studies. The four agricultural management systems were no tillage (minimum tillage) with cover crops in the intervals between economic crops, standard tillage with cover crops, minimum tillage without cover crops and standard tillage without cover crops. The economic crops were sorghum and garbanzo beans. A soil column system was used in laboratory studies to evaluate the nitrogen mineralization ecosystem service associated with nematode assemblages in soils from the four management systems compared to that in defaunated soil. In an additional comparison, defaunated soil was amended with mineral fertilizer solution for comparison with the mineralization service of the soil fauna. Management systems using cover crops, which created a continuity of both photosynthetic production and roots in the soil, strongly enhanced the nematode assemblages in the field soil. Management systems with cover crops had greater total abundance, measured as numbers, biomass and metabolic footprints, of nematodes, and also of the functional guilds of nematodes considered important in soil fertility and as prey for predators. Leachates from soil columns with intact nematode assemblages had greater total mineral nitrogen and supported greater plant growth than those from defaunated columns. Soil carbon levels in field plots were strongly affected by the management systems. The biomass and diversity-weighted footprint of bacterivore and microbivore (Bacterivores plus fungivores) nematodes, in turn, were correlated with levels of soil carbon.
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structure functions and interguild relationships of the soil nematode assemblage in organic vegetable production
Applied Soil Ecology, 2012Co-Authors: H Ferris, Sara Sanchezmoreno, Eric B BrennanAbstract:Abstract The abundance and metabolic footprints of soil nematodes were quantified during four of eight years of an intensive organic vegetable production system. Treatment variables included cover crop mixtures and compost application rates. The abundances of bacterivore and fungivore nematodes were enhanced by the annual use of winter cover crops but showed no relationship to the level of residual soil organic matter. Metabolic footprints, based on biomass and respiratory activity, were calculated for functional guilds and ecosystem services of the nematode assemblage. The enrichment footprint, representing the ecosystem service of nutrient mineralization, was related to the level of soil organic carbon. It was strongly related to the metabolic footprint of bacterivore nematodes and both were enhanced in treatments that were cover cropped annually. Cover-cropped treatments also had a slightly higher herbivore footprint, suggesting support of some taxa of plant-feeding nematodes. The structure footprint, reflecting the metabolic activity of higher trophic level nematodes, including the predators of opportunistic species, did not differ among cover crop and compost amendment treatments. However, enrichment footprints were correlated with bacterivore footprints, which represented the predominantly bacterivore resources available to predators. Abundance of predators increased as a function of the abundance of those nematode prey that can be amplified by organic inputs. The functional connectance, represented by spatial co-location, between predators and amplifiable prey was greater in treatments with a greater abundance of predators. The functional connectance between predators and herbivore prey, representing a management target, was strongly related to the functional connectance between predators and amplifiable prey. We conclude that cover crops not only affect organisms at the entry level of the web but that resources are also transferred to higher trophic links which increases top-down pressure on plant-parasitic nematodes.
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soil management to enhance bacterivore and fungivore nematode populations and their nitrogen mineralisation function
Applied Soil Ecology, 2004Co-Authors: H Ferris, Robert C Venette, Kate M ScowAbstract:We tested the hypotheses that management of the soil food web in the fall would enhance grazing on bacteria and fungi by microbivorous nematodes in the spring, consequently increasing N availability in cover-crop driven organic and low-input farming systems. The food web was manipulated by irrigating the dry soil of late summer and/or providing carbon sources. By creating conditions conducive for biological activity, we increased the abundance of bacterivore and fungivore nematodes in the fall and the following spring. Greater biological activity in the soil enhanced concentrations of mineral N available to the subsequent summer tomato crop. Mineral N concentration in the spring was associated with abundance of bacterivore nematodes, and with the corresponding Enrichment Index (EI) provided by nematode community analysis. Because environmental conditions that favour increase of bacterivore nematodes probably also favour other microbial grazers, including protozoa, the abundance of bacterivore nematodes may be an indicator of overall grazing activity and N mineralisation rates from soil fauna. Decomposition pathways in the spring, inferred from nematode bioindicators, were dominated by bacteria in plots that had been irrigated the previous fall while fungi were more prevalent in those that had not. The responses of omnivore and predator nematodes to our treatments were not consistent and there was no evidence that regulation of opportunist species by predators would be enhanced by the management practices imposed.
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structural and functional succession in the nematode fauna of a soil food web
Applied Soil Ecology, 2003Co-Authors: H Ferris, M M MatuteAbstract:Soil microplots were amended with organic materials of varying nature and complexity but providing similar amounts of carbon. Materials were either placed on the soil surface or incorporated. Unamended and mineral fertilizer control plots were established. Plots were maintained vegetation-free so that the food web activity was fueled by resident soil organic matter and the input material. Enrichment-opportunist bacterivore nematodes increased rapidly in response to low C/N plant materials and, to a lesser extent, to more complex materials. General-opportunist Bacterivores increased in all plots, but at a slower rate. Fungivore nematodes also increased gradually in all plots but most rapidly in those amended with higher C/N and more complex materials. Indices derived from nematode faunal analysis suggested a constant rate of succession from enrichment-opportunist to general-opportunist bacterivore guilds across all treatments, probably mediated by bacterial abundance and differences in life course characteristics of the respective taxa. The rate of succession from bacterivore to fungivore nematodes was greatest in plots receiving high C/N materials. Succession to fungivory, presumably indicating a shift from bacterial to fungal decomposition channels, was slowest in those plots with a high level of organismal metabolic activity, as measured by soil respiration. The cumulative amounts of N mineralized in the plots were directly related to the enrichment index (EI), based on the abundance of opportunistic bacterial- and fungal-feeding nematodes. The amounts of mineralized N were inversely related to the slope of the channel index (CI), that is, the rate at which decomposition changed from bacterial to fungal. Maintenance of adequate soil fertility in systems driven by organic input may require maintenance of food web structure and function as indicated by high levels of enrichment-opportunist bacterivore nematodes. That will require frequent supply of labile organic sources. Allowing food web succession to guilds that indicate lower mineralization potential will result in lower levels of soil fertility.
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structural and functional succession in the nematode fauna of a soil food web
Applied Soil Ecology, 2003Co-Authors: H Ferris, M M MatuteAbstract:Soil microplots were amended with organic materials of varying nature and complexity but providing similar amounts of carbon. Materials were either placed on the soil surface or incorporated. Unamended and mineral fertilizer control plots were established. Plots were maintained vegetation-free so that the food web activity was fueled by resident soil organic matter and the input material. Enrichment-opportunist bacterivore nematodes increased rapidly in response to low C/N plant materials and, to a lesser extent, to more complex materials. General-opportunist Bacterivores increased in all plots, but at a slower rate. Fungivore nematodes also increased gradually in all plots but most rapidly in those amended with higher C/N and more complex materials. Indices derived from nematode faunal analysis suggested a constant rate of succession from enrichment-opportunist to general-opportunist bacterivore guilds across all treatments, probably mediated by bacterial abundance and differences in life course characteristics of the respective taxa. The rate of succession from bacterivore to fungivore nematodes was greatest in plots receiving high C/N materials. Succession to fungivory, presumably indicating a shift from bacterial to fungal decomposition channels, was slowest in those plots with a high level of organismal metabolic activity, as measured by soil respiration. The cumulative amounts of N mineralized in the plots were directly related to the enrichment index (EI), based on the abundance of opportunistic bacterial- and fungal-feeding nematodes. The amounts of mineralized N were inversely related to the slope of the channel index (CI), that is, the rate at which decomposition changed from bacterial to fungal. Maintenance of adequate soil fertility in systems driven by organic input may require maintenance of food web structure and function as indicated by high levels of enrichment-opportunist bacterivore nematodes. That will require frequent supply of labile organic sources. Allowing food web succession to guilds that indicate lower mineralization potential will result in lower levels of soil fertility. © 2003 Elsevier Science B.V. All rights reserved.
Xiaoke Zhang - One of the best experts on this subject based on the ideXlab platform.
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ecosystem services of the soil food web after long term application of agricultural management practices
Soil Biology & Biochemistry, 2017Co-Authors: Jeffrey P Mitchell, H Ferris, Xiaoke Zhang, Wenju LiangAbstract:Abstract The structure of soil nematode assemblages was assessed in field plots in the San Joaquin Valley of California which have 16-year management system histories. Attributes of the ecosystem functions of the assemblages were determined in laboratory studies. The four agricultural management systems were no tillage (minimum tillage) with cover crops in the intervals between economic crops, standard tillage with cover crops, minimum tillage without cover crops and standard tillage without cover crops. The economic crops were sorghum and garbanzo beans. A soil column system was used in laboratory studies to evaluate the nitrogen mineralization ecosystem service associated with nematode assemblages in soils from the four management systems compared to that in defaunated soil. In an additional comparison, defaunated soil was amended with mineral fertilizer solution for comparison with the mineralization service of the soil fauna. Management systems using cover crops, which created a continuity of both photosynthetic production and roots in the soil, strongly enhanced the nematode assemblages in the field soil. Management systems with cover crops had greater total abundance, measured as numbers, biomass and metabolic footprints, of nematodes, and also of the functional guilds of nematodes considered important in soil fertility and as prey for predators. Leachates from soil columns with intact nematode assemblages had greater total mineral nitrogen and supported greater plant growth than those from defaunated columns. Soil carbon levels in field plots were strongly affected by the management systems. The biomass and diversity-weighted footprint of bacterivore and microbivore (Bacterivores plus fungivores) nematodes, in turn, were correlated with levels of soil carbon.
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The abundances of total nematodes and trophic groups among different water or/and N addition treatments.
2013Co-Authors: Xiaoming Sun, Xiaoke Zhang, Shixiu Zhang, Guanhua Dai, Shijie Han, Wenju LiangAbstract:Bars indicate standard errors. OP, omnivores-predators; PP, plant-parasites; FF, fungivores; BF, Bacterivores.
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soil microbial food web responses to free air ozone enrichment can depend on the ozone tolerance of wheat cultivars
Soil Biology & Biochemistry, 2012Co-Authors: Qi Li, Xiaoke Zhang, Caiyan Lu, Yong Jiang, Wenju LiangAbstract:Soil processes are driven by soil organisms and their interactions with plants and soil abiotic conditions. Climate changes may directly or indirectly alter soil processes and the organisms mediating these processes. Although aboveground influences of ozone have been studied widely on agroecosystems, the effects on belowground processes are poorly understood. This study aimed to investigate the effects of elevated ozone concentration [O3] on the components of soil microbial food webs and compare their responses between ozone-sensitive and ozone-tolerant wheat cultivars. The responses of soil biota to elevated [O3] varied between the two wheat cultivars. Fungal PLFA and the fungi to bacteria ratio decreased following elevated [O3], especially in the rhizospheric soil of ozone-tolerant wheat. Nematode functional guilds were sensitive to elevated [O3] and cultivar effects. At wheat jointing stage, Bacterivores belonging to K-strategies decreased following elevated [O3], while fungivores exhibited a reverse trend. The abundance of flagellates decreased in ozone-tolerant wheat, but increased in ozone-sensitive wheat following elevated [O3]. However, an opposite trend was found in the Bacterivores belonging to r-strategies. In conclusion, wheat cultivars play an important role in determining the effects of elevated [O3] on soil food web. The responses of soil biota to elevated [O3] were greater in ozone-tolerant wheat than in ozone-sensitive wheat, which may in turn have influenced soil organic matter decomposition and nutrient turnover.
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nematode faunal response to long term application of nitrogen fertilizer and organic manure in northeast china
Soil Biology & Biochemistry, 2009Co-Authors: Wenju Liang, Xiaoke Zhang, Yilai Lou, Shuang Zhong, Jingkuan WangAbstract:Nematode faunal response to the long-term (20-year) application of nitrogen fertilizer and organic manure was monitored in a Hapli-Udic Cambosol of Northeast China, where no fertilizer (C), nitrogen fertilizer (N), organic manure (M) and nitrogen fertilizer plus organic manure (N + M) treatments were compared. The obtained results showed that total nematode abundance responded positively to the M and N + M treatments. The numbers of Acrobeloides increased in the M and N + M treatments at maize jointing and booting stages, and those of Aphelenchoides were higher in the N + M treatment than in the N treatment at maize ripening stage. Early in the growing season, the numbers of Bacterivores of cp-1 (cp, colonizer-persister) and cp-2 guilds were higher in the M and N + M treatments than in the N treatment, while those of Bacterivores and fungivores of cp-4 guilds were higher in the C treatment than in the N, M and N + M treatments. Except at maize seedling stage, the numbers of fungivores of cp-2 and herbivores of cp-3 guilds were higher in the N + M treatment than in the C treatment. Ratios of the weighted abundance of representatives of specific functional guilds were used as indicators of food web structure, enrichment and decomposition channels. Values of the enrichment index (EI) at maize seedling and jointing stages were higher in the M and N + M treatments than in the C and N treatments, while an opposite trend was observed in the channel index (CI). Higher El and lower Cl suggest an enriched soil food web dominated with bacterial decomposition channels in the M and N+M treatments. (C) 2008 Elsevier Ltd. All rights reserved.
T. E. Miller - One of the best experts on this subject based on the ideXlab platform.
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Modelling the relationship between a pitcher plant (Sarracenia purpurea) and its phytotelma community: mutualism or parasitism?
Functional Ecology, 2008Co-Authors: Nicolas Mouquet, Tanguy Daufresne, S. M. Gray, T. E. MillerAbstract:1. To improve our understanding of the relationship between the pitcher plant ( Sarracenia purpurea ) and the phytotelma community inhabiting its leaves we built an exploratory, mechanistic model based on stochiometric constraints on carbon and nitrogen associated with prey decomposition. 2. Our theoretical results suggest that the phytotelma community is acting as a mineralizing system producing nitrogen for the plant. This is confirmed by data collected in the field and in the literature, that show the amount of nitrogen produced by the decomposition of prey is sufficiently high to be considered as a major source of nitrogen for the plant. 3. In our model, nitrogen yield is higher if the phytotelma community is restricted to bacteria alone than when the full food web is present. Nitrogen availability is negatively affected by Bacterivores (rotifers and protozoa mostly) and positively affected by a cascading effect of mosquito larvae. 4. When sedimentation rate is high, mosquitoes have a global positive effect on nitrogen production because they indirectly reduce the amount of nitrogen lost through sedimentation more than they export nitrogen through pupation. On the other hand, when sedimentation rate is low there is a hump-shaped relationship between the uptake rate of Bacterivores by mosquito larvae and the nitrogen yield in the plant. 5. We conclude that plant–bacteria and plant–mosquito interactions are predominantly mutualistic, whereas plant–bacterivore interactions are predominantly parasitic. Our work also illustrates how ecosystem properties (here nitrogen production by the phytotelma community) can be understood as a function of trophic complexity and can be seen as a product of selection at the scale of a community.
Heikki Setala - One of the best experts on this subject based on the ideXlab platform.
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interplay of omnivory energy channels and c availability in a microbial based soil food web
Biology and Fertility of Soils, 1998Co-Authors: Juha Mikola, Heikki SetalaAbstract:To study the effects of omnivory on the structure and function of soil food webs and on the control of trophic-level biomasses in soil, two food webs were established in microcosms. The first one contained fungi, bacteria, a fungivorous nematode (Aphelenchoides saprophilus) and a bacterivorous nematode (Caenorhabditis elegans), and the second one fungi, bacteria, the fungivore and an omnivorous nematode (Mesodiplogaster sp.) feeding on both bacteria and the fungivore. Half of the replicates of each food web received additional glucose. The microcosms were sampled destructively at 5, 9, 13 and 19 weeks to estimate the biomass of microbes and nematodes and the soil NH4+-N concentration. The evolution of CO2 was measured to assess microbial respiration. Microbial respiration was increased and soil NH4+-N concentration decreased by the addition of glucose, whereas neither was affected by the food-web structure. Supplementary energy increased the biomass of fungi and the fungivore, but decreased the biomass of bacteria, the bacterivore and the omnivore. The omnivore achieved greater biomass than the bacterivore and reduced the bacterial biomass less than the bacterivore. The biomass of the fungivore was smaller in the presence of the omnivore than in the presence of the bacterivore at three sampling occasions. Fungal biomass was not affected by food-web structure. The results show that the effects of the omnivore were restricted to its resources, whereas more remote organisms and soil processes were not substantially influenced. The results also indicate that the presence of an omnivore does not necessarily alter the control of populations as compared with a food web containing distinct trophic levels, and that the fungal and bacterial channels may respond differently to changes in energy supply.
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relating species diversity to ecosystem functioning mechanistic backgrounds and experimental approach with a decomposer food web
Oikos, 1998Co-Authors: Juha Mikola, Heikki SetalaAbstract:Hypotheses have recently been formulated to elucidate the relationship between species diversity and ecosystem functioning. Using previously published mechanisms as a starting point we suggest that common mechanisms can be provided for this relationship by using the concepts of niche and trophic-level dynamics. The reasoning is the following: if remaining species within a trophic level can modify their niches as other species disappear, production within the level remains unchanged, whereas in the absence of niche modification production decreases. Decreased production within a trophic level affects biomass and production at other levels as predicted by trophic-dynamic models. Changes in biomass and production finally bring about changes in ecosystem functioning. In the redundant species hypothesis remaining species can modify their niches, and so functioning remains unchanged. In the predictable change hypothesis (our counterpart for the rivet hypothesis), and in the idiosyncratic response hypothesis, remaining species cannot modify their niches, leading to predictable and unpredictable changes in functioning, respectively. Unpredictable changes are due to differences in the characteristics of species and indirect interactions between populations. We tested the hypotheses and the suggested mechanisms using a soil food web with three trophic levels: microbes, microbivorous nematodes and a predatory nematode. We established one diverse (3 Bacterivores and 3 fungivores) and three simple (1 bacterivore and 1 fungivore) food webs and found that differences in trophic-level biomasses between the diverse and simple food webs were idiosyncratic. Unpredictability resulted from differences in microbivore characteristics - their efficiency in resource utilisation and vulnerability to predation and competition. Changes in microbial respiration and total mineralisation of C and N, i.e., system functioning, were also idiosyncratic rather than redundant or predictable when diversity was reduced, although idiosyncracy was not as clear as in the case of trophic-level biomasses. We conclude that predicting the influence of declining species diversity on trophic-level dynamics and ecosystem processes is difficult, at least in food webs with a small initial number of species, unless the characteristics of species and the nature of their interactions are known.
