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Human management practices and large detritivores such as earthworms incorporate plant litter into the soil, thereby forming a heterogeneous soil environment from which plant roots extract nutrients. In a greenhouse experiment we investigated effects of earthworms and spatial distribution of (15)N-labelled grass litter on plants of different functional groups [ Lolium perenne (grass), Plantago lanceolata (forb), Trifolium repens (legume)]. Earthworms enhanced shoot and root growth in L. perenne and P. lanceolata and N uptake from organic litter and soil in all plant species. Litter concentrated in a patch (compared with litter mixed homogeneously into the soil) increased shoot biomass and (15)N uptake from the litter in L. perenne and enhanced root proliferation in P. lanceolata when earthworms were present. Growth of clover (T. repens) was rather independent of the presence of earthworms and organic litter distribution: nevertheless, clover took up more nitrogen in the presence of earthworms and exploited more (15)N from the added litter than the other plant species. The magnitude of the effects of earthworms and organic litter distribution differed between the plant species, indicating different responses of plants with contrasting root morphology. Aphid (Myzus persicae) reproduction was reduced on P. lanceolata in the presence of earthworms. We suggest that earthworm activity may indirectly alter plant chemistry and hence defence mechanisms against herbivores.

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The registration efficiency of the TSI model 3025 ultrafunction of the DMA, the counting efficiencies of confine condensation particle counter for Ag and NaCl densation nucleus counters (CNC) for monodisperse particles of between 2 and 20 nm in diameter was Ag and NaCl particles were estimated. In addition, the determined. Taking into account the different shapes dependence of the CNC registration efficiency on the of the input aerosol size distributions entering the particle concentration was investigated. differential mobility analyzer (DMA) and the transfer

Particle losses in a differential mobility analyzer (TSI, the particle losses have to be considered in the diameter Model 3071) caused by diffusive deposition and Brownian size range below 30 nm (50% at 7 nm). From the diffusion are measured for particles in the diameter size measured penetration values, an effective tube length is range between 3 and 100 nm. For small sampling and derived which is useful to calculate particle losses for aerosol flow rates (0.3 liters/min) at 20 nm, nearly SO?& other flow rates through the analyzer. of the primary particles are lost; and for 2 liters/min,