Grazing in a porous environment. 2. Nematode community structure

摘要: The influence of soil matric potential on nematode community composition and grazing associations were examined. Undisturbed cores (5 cm diameter, 10 depth) collected in an old field dominated by perennial grasses a Hinckley sandy loam at Peckham Farm near Kingston, Rhode Island. Ten pairs incubated −3, −10, −20 −50 kPa after saturation for 21–28 or 42–58 days. Nematodes extracted using Cobb's decanting sieving method followed sucrose centrifugal-flotation identified to family genus. Collembola enchytraeids present also enumerated because they are grazers that reside air-filled spaces. Direct counts bacteria fungi made estimate biovolume fluorescein isothiocyanate diacetate stains, respectively. Trophic diversity maturity indices calculated communities. Three patterns effect observed taxa. One, there was consistent all seasons Alaimus, Monhysteridae, Prismatolaimus, Paraxonchium Dorylaimoides. Two, some effects among other inconsistent Aphelenchoides, Aphelenchus, Cephalobidae, Coomansus, Eudorylaimus, Huntaphelenchoides, Panagrolaimidae, Paraphelenchus, Sectonema, Tripyla. Third, always Aphanolaimus, Aporcelaimellus, Bunonema, Rhabditidae, Tylencholaimus. As predicted, fungal bacterial biomass responded oppositely potential. Total greater −3 than (P=0.0095). −50, −10 Neither bacterial-feeding, fungal-feeding nor predacious nematodes correlated significantly with biomass. Omnivorous positively number bacterial-feeding nematodes; nematodes. Numbers more often microbial-grazing numbers drier moist soils. From this study, we propose two mechanisms may explain structure changes potential: differential anhydrobiosis and/or enclosure hypotheses. later suggests drying generates pockets moisture aggregates become isolated from one another enclosing their food relatively high concentrations creating patches activity separated larger areas inactivity.