02469nas a2200229   4500008004100000245012000041210006900161260009100230300001200321490000700333520160300340653002001943653001901963653001401982653001301996653001802009653001202027653002402039100002102063700001802084856013702102       2009                        eng d00aDistribution and population structure of two bacterial-feeding nematode genera in ice-free areas in East Antarctica0 aDistribution and population structure of two bacterialfeeding ne  aPLANTIJNSTRAAT 2, P O BOX 9000, 2300 PA LEIDEN, NETHERLANDSbBRILL ACADEMIC PUBLISHERS  a189-2010 v113 aVery dense populations of nematodes of the genera Plectus and Panagrolaimus were found in moss cushions and in ornithogenic soils in a number of localities on mountain outcrops (nunataks) penetrating the ice sheet and in a coastal oasis in East Antarctica. These high abundances permitted analysis of the structure of populations from various sites. Patterns of distribution and size-class composition in nematode populations from the Basen nunatak, and from scattered samples taken in a larger area including several nunataks and one coastal oasis in Dronning Maud Land, were investigated. It is suggested that the composition of developmental stages and structure of the nematode populations are influenced by environmental conditions such as food supply, temperature and maybe predation or competition from coexisting populations of tardigrades, protozoans and rotifers. The results indicated that the population dynamics were not synchronised among the sites. In several populations the animals appeared well fed with a high frequency of gravid females. In the more extreme localities, in particular, the proportion of adults was very high, and in these sites the recruitment to the populations appeared to be rather low as indicated by the low proportion of juveniles. The structure of the nematode populations seemed little influenced by various combinations of co-occurring tardigrades or rotifers. There were some differences in population structure between nematode populations from different nunataks which could possibly be caused by genetic variability due to long periods of isolation.10aEast Antarctica10alength classes10anematodes10anunataks10aPanagrolaimus10aPlectus10apopulation dynamics1 aSohlenius, Bjorn1 aBostrom, Sven  uhttps://nematoda.myspecies.info/content/distribution-and-population-structure-two-bacterial-feeding-nematode-genera-ice-free-areas-e03320nas a2200217   4500008004100000022002200041245010700063210006900170260014200239300001200381490000700393520241900400100002002819700002102839700002102860700001902881700001802900700002202918700002502940856013702965       2009                        eng d  a0012-9658 (Print)00aLong-term effects of plant diversity and composition on soil nematode communities in model grasslands.0 aLongterm effects of plant diversity and composition on soil nema  aDepartment of Ecology, Swedish University of Agricultural Sciences (SLU), Box 7044, SE-750 07 Uppsala, Sweden. maria.viketoft@ekol.slu.se  a90–990 v903 aAn important component of plant-soil feedbacks is how plant species identity anddiversity influence soil organism communities. We examine the effects of grassland plant species growing alone and together up to a richness of 12 species on nematode diversity and feeding group composition, eight years after the establishment of experimental grassland plots at the BIODEPTH site in northern Sweden. This is a substantially longer time than most other experimental studies of plant effects on soil fauna. We address the hypotheses that (la) higher species or functional diversity of plants increases nematode diversity, as well as influences nematode community composition. Alternatively, (1b) individual plant species traits are most important for nematode diversity and community composition. (2) Plant effects on soil organisms will decrease with increasing number of trophic links between plants and soil fauna. Plant species identity was often more important than plant diversity for nematode community composition, supporting hypothesis 1b. There was a weak positive relation between plant and nematode richness;which could be attributed to the presence of the legume Trifolium pratense, but also to some other plant species, suggesting a selection or sampling effect. Several plant species in different functional groups affected nematode community composition. For example, we found that legumes increased bacterial-feeding nematodes, most notably r-selected Rhabditida, while fungal-feeding nematodes were enhanced by forbs. Other bacterial feeders and obligate root feeders were positively related to grasses. Plant effects were usually stronger on plant-, bacterial- and fungal-feeding nematodes than on omnivores/predators, which supports hypothesis 2. Our study suggests that plant identity has stronger effects than plant diversity on nematode community composition, but when comparing our results with similar previous studies the effects of particular plant species appear to vary. We also found that more productive plant species affected bacterial-feeding nematodes more than fungal feeders. Moreover, we observed stronger effects the fewer the number of trophic links there were between a nematode feeding group and plants. Although we found clear effects of plants on soil nematodes, these were probably not large enough to result in strong and persistent plant-soil-organism-plant feedback loops.1 aViketoft, Maria1 aBengtsson, Janne1 aSohlenius, Bjorn1 aBerg, Matty, P1 aPetchey, Owen1 aPalmborg, Cecilia1 aHuss-Danell, Kerstin  uhttps://nematoda.myspecies.info/content/long-term-effects-plant-diversity-and-composition-soil-nematode-communities-model-grasslands