Soil arthropods beneficially rather than detrimentally impact plant performance in experimental grassland systems of different diversity     

Nico Eisenhauer  Alexander C.W. Sabais  Stefan Scheu 《Soil biology & biochemistry》2010,42(9):1418-1424

Impacts of belowground insecticide application on plant performance and changes in plant community structure almost uniformly have been ascribed to reduced belowground herbivory, although recent studies reported distinct side effects on detritivore soil animals, particularly on Collembola. Consequently, it remains controversial if the resulting soil feedbacks on plants are due to alterations in arthropod herbivory or to changes in the activity of detritivores. We investigated the impacts of the application of a commonly used belowground insecticide (chlorpyrifos) on soil animals and soil feedbacks on model plant species representing two main plant functional groups of grassland communities, the grass Lolium perenne and the forb Centaurea jacea.Insecticide application decreased soil insect herbivore densities considerably. However, also Collembola densities and diversity decreased markedly due to insecticide application and this was most pronounced in Entomobryidae, Isotomidae, Hypogastruridae, and Sminthuridae. While densities of other detritivore taxa were not affected or even increased (Oribatida) in insecticide subplots, that of predators mostly decreased.Both model plant species built considerably more biomass in control subplots than in insecticide subplots irrespective of characteristics of the resident plant community. This suggests that soil feedbacks on plants were not due to belowground herbivory and highlights the significance of alternative mechanisms responsible for insecticide-mediated soil feedbacks on plants. The deterioration of model plant species’ performances in insecticide subplots most likely was due to decreased densities of Collembola resulting in the deceleration of nutrient cycling and plant nutrition. The results suggest that it is oversimplistic to only ascribe insecticide-mediated soil feedbacks on plants to belowground herbivores. The results further indicate that in the present study the impact of arthropod detritivores on plant productivity was more important than that of belowground herbivores. This emphasizes that plant-soil arthropod interactions in grassland might be based on both facilitative and antagonistic interrelationships.  相似文献   

Plant diversity enhances the reliability of belowground processes     

Alexandru Milcu  Elisa Thebault  Nico Eisenhauer 《Soil biology & biochemistry》2010,42(12):2102-2110

Theory predicts that the probability that an ecosystem will provide a consistent level of functioning over a given unit of time, i.e. the reliability of ecosystem processes, should increase with species richness. There is growing evidence that plant diversity increases the temporal stability of productivity, but only a few studies have investigated its impact on the reliability of ecosystem processes, and information on whether this propagates to the belowground system is virtually lacking. Using a microcosm experiment with plant communities varying in species and functional group diversity and two decomposer groups (earthworms and Collembola) we investigated the effects of plant diversity on the reliability of the belowground system and vice versa, the effect of decomposers on the reliability of plant productivity. Generally, plant diversity increased the reliability of above- and belowground processes by significantly increasing the reliability of eight out of eleven measured ecosystem parameters (six out of nine belowground responses). Plant functional group diversity had a stronger stabilising effect than species richness on above- and belowground processes including plant shoot and total biomass, microbial basal respiration and Collembola densities. By contrast, in the presence of both decomposer groups the reliability of decomposer populations was reduced. The results indicate that plant diversity effects propagate into the belowground system and increase the reliability of belowground processes via more consistent plant derived belowground inputs.  相似文献   

Using earthworms as model organisms in the laboratory: Recommendations for experimental implementations   总被引：2，自引：0，他引：2  

Heinz-Christian Fründ  Kevin Butt  Nico Eisenhauer  Gregor Ernst  Martin Schädler 《Pedobiologia》2010,53(2):119-125

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Kinetics of Zn and Cd accumulation in the isopod Porcellio scaber exposed to contaminated soil and/or food     

Martina G. Vijver  Jos P.M. Vink  Nico M. van Straalen  Cornelis A.M. van Gestel 《Soil biology & biochemistry》2006,38(7):1554-1563

To derive accumulation kinetics from different exposure matrices and account for the contribution of different exposure routes, the isopod Porcellio scaber was exposed to Cd and Zn, either in soil or in food, and a combination of both. Accurate uptake and elimination kinetics of Zn and Cd were determined using radioisotopes, allowing non-destructive time measurements. To describe the data, a simple kinetic model was used accounting for the internal distribution of the metals. A strong influence of the elimination kinetics, together with the metal fraction that is compartmentalized in a storage fraction, was found explaining the Cd steady-state level reached in the isopods. Zn turnover kinetics were relatively fast within the first days of exposure and elimination, followed by slow Zn kinetics from the storage compartment. The storage fraction appeared to be inert for elimination of both Zn and Cd within the experimental duration of 32 days and the fraction of metal taken up that was stored in this fraction was influenced by the uptake source. The quantity of metals taken up from soil or food depended on the concentration. For both Zn and Cd, the uptake rate constant from soil equalled the uptake rate constant from food, moreover, the uptake from both routes was shown to be additive. Therefore, it is concluded that the relative contribution of both routes (via soil or food) is explained by the partitioning of metals between soil and food.  相似文献   

Microbial links and element flows in nested detrital food-webs     

Andrei D. Pokarzhevskii  Nico M. van Straalen  Dmitrii P. Zaboev  Andrei S. Zaitsev 《Pedobiologia》2003,47(3):213-224

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Metal concentrations in soil and invertebrates in the vicinity of a metallurgical factory near Tula (Russia)     

Nico M. van Straalen  Ruslan O. Butovsky  Andrei D. Pokarzhevskii  Andrei S. Zaitsev  S. Cornelis Verhoef 《Pedobiologia》2001,45(5):451

To investigate the effects of emissions from a large metal works near Tula in the Russian Federation, we measured concentrations of iron, manganese, zinc, copper, nickel, lead and cadmium in soil, litter and invertebrates at four sampling sites at different distances from the factory. The sites were located in woodlands in the bed of the Voronka river, near the town of Kosaya Gora in the district of Tula. Additional soil properties (organic matter content, clay content, water holding capacity, Ca, Mg, N, P, and pH) were measured that could explain differences in the bioavailability of the metal burdens. It appeared that the factory is a source of Fe, Mn, Zn, Cu, Ni and Pb. One of the sampling sites had a high nitrogen content in the litter due to emissions from a fertilizer plant in the area. Most of the metal contamination was limited to the immediate surroundings and did not extend beyond a distance of 5 km. Only the site close to the factory can be considered as polluted, however, background concentrations of metals in the Tula area seem to be significantly lower than in present Western European soils and a reference system still has to be developed. Exchangeable metal concentrations (0.01 M CaCl₂ extracts from soil) were very low and were not correlated with the total concentrations, indicating low bioavailability of the pollution. At the most polluted site, concentrations of all metals were positively correlated with each other; correlations decreased with increasing distance. Metal concentrations in soil were often negatively correlated with organic matter content, especially so for nickel. Metal concentrations in invertebrates showed considerable variation between individual species, however, some general patterns were obvious. Concentrations were high in earthworms, oribatid mites and carabid beetles, and low in springtails, centipedes and spiders. There was no relationship between the trophic position of a species and its metal accumulating ability. Iron concentrations in invertebrates at the polluted site were a factor of 2 to 4 higher than at the most remote (reference) site; for zinc and copper the internal concentrations were also elevated, but to a lesser extent than the soil concentrations. The data illustrate the extremely complicated relationship between metal residues in invertebrates and metal concentrations in soil. For most of the saprophageous and predatory arthropods studied total concentrations nor exchangeable concentrations in soil are good predictors; species-specific feeding mechanisms and metal physiologies seem to be the main determinants.  相似文献   

Species diversity and metal accumulation in oribatid mites (Acari, Oribatida) of forests affected by a metallurgical plant     

Andrei S. Zaitsev  Nico M. van Straalen 《Pedobiologia》2001,45(5)

A study was made of oribatid mite communities and their responses to metal contamination derived from the Kosogorsky metallurgical plant located in the Tula District, Russia. Mite communities were sampled in three different seasons in four sites at different distances from the smelter. Concentrations of zinc, copper, cadmium, lead and iron were measured in ten mite species. The data show that the mite community as a whole is quite tolerant to the metal contamination caused by the Kosogorsky plant. At the polluted sites some species typical for nutrient-rich soils appeared, but community structure and species diversity were not seriously affected by metal contamination. In general, oribatid mites accumulated metals to very high internal concentrations. Average Cu, Cd, Pb and Fe concentrations did not differ significantly between species, but Zn did, and its level was associated with the mode of feeding of the species. Microphytophagous species, feeding exclusively on fungi, accumulated zinc in higher concentrations than other mites. This study illustrates the potential for bioindication by the little studied but species-rich group of soil oribatids.  相似文献   

Soil Acidification and Solute Budgets for Forested Lysimeters in Nordrhein-Westfalen     

Hans J. M. van Grinsven  Bart G. Wesselink  Manfred Schroeder  Nico van Breemen 《植物养料与土壤学杂志》1991,154(3):181-188

Solute budgets and nitrogen use were quantified in two 400 m² forested lysimeters in St. Arnold, Nordrhein-Westfalen. The lysimeters are covered by a mixture of oak-beech and Weymouth pine, respectively. The average bulk deposition between May 1985 and May 1987 of NH, SO and NO₃ was 1.1, 1.7, and 0.4 kmol_c ha^?1 yr^?1 in the deciduous stand and 2.1, 2.1, and 0.8 kmol_c ha^?1 yr^?1 in the coniferous stand. The input of N is almost completely retained in the deciduous stand. In the coniferous stand about 30% of this N-input is leached as NO₃. Due to N-transformations, total proton turnover is 4.4 kmol_c ha^?1 yr^?1 in the coniferous stand and only 2.5 kmol_c ha^?1 yr^?1 in the deciduous stand. Ca-mobilization is the major acid buffering process in both lysimeters. Only the deciduous stand was limed in 1980 (90 kmol_c/ha). Mobilization of Al is only relevant down to a soil depth of 30 cm. Below a 30 cm depth, Al is immobilized. The amounts of exchangeable and silicate-bound Ca in the soil underlying the coniferous stand are very small, but no evidence was found for explanation of the observed high Ca-mobilization by artificial Ca-sources.  相似文献   

Soil Surface‐Active Fauna in Degraded and Restored Lands of Northeast Brazil     

Ademir Srgio Ferreira de Araújo  Nico Eisenhauer  Luís Alfredo Pinheiro Leal Nunes  Luiz Fernando Carvalho Leite  Simone Cesarz 《Land Degradation \u0026amp; Development》2015,26(1):1-8

Land degradation reducing vegetation cover may affect the soil surface‐active fauna because both aboveground and belowground invertebrates depend on complex plant communities. In this study, we evaluated the effect of land degradation and restoration on soil fauna in northeast Brazil. Sites differed in degradation status: native vegetation, moderately degraded land, highly degraded land, and land under restoration for 4 years. Araneae and Coleoptera densities were significantly higher in natural vegetation and restored land (8 ± 4 ind./trap and 41 ± 21 ind./trap, respectively) than in degraded lands (−73% and −81%, respectively). The density of Formicidae was significantly higher in natural vegetation (206 ± 181 ind./trap) than in highly degraded land (32 ± 24 ind./trap), while restored land (51 ± 10 ind./trap) and moderately degraded land (37 ± 14 ind./trap) did not differ significantly from the other degradation levels. The density of Orthoptera did not follow the aforementioned patterns, while invertebrate groups mostly had highest densities in natural land and restored land. Linear regressions showed a strong negative relation between faunal density and soil bulk density, and a positive relation with soil organic matter due to an increase in plant cover. Our results indicate that land degradation simplifies soil surface‐active invertebrate communities with pronounced decreases in the density of Araneae, Coleoptera, and Formicidae, but that land restoration practices may recover the density of soil fauna even after only 4 years. Araneae, Coleoptera, and Formicidae respond sensitively to land degradation and restoration practice and are suggested as indicator groups for restoration success. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Dendritic cell-induced memory T cell activation in nonlymphoid tissues   总被引：1，自引：0，他引：1  

Wakim LM  Waithman J  van Rooijen N  Heath WR  Carbone FR 《Science (New York, N.Y.)》2008,319(5860):198-202

Secondary lymphoid organs are dominant sites of T cell activation, although many T cells are subsequently retained within peripheral tissues. Currently, these nonlymphoid compartments are viewed as sites only of effector T cell function, without the involvement of renewed induction of immunity via the interactions with professional antigen-presenting cells. We describe a method of reactivation of herpes simplex virus to examine the stimulation of tissue-resident T cells during secondary challenge. The results revealed that memory CD8+ T cell responses can be initiated within peripheral tissues through a tripartite interaction that includes CD4+ T cells and recruited dendritic cells. These findings lend evidence for the existence of a sophisticated T cell response mechanism in extra-lymphoid tissues that can act to control localized infection.  相似文献