| Popis: |
Invertebrate colonization and establishment in grassland and Salix on reclaimed cutaway peat, and the influence of invertebrates on soil fertility and plant growth, were studied. After 2 years, population densities of 74 000 Collembola, 66 000 Acari, 1400 Coleoptera and 6000 Diptera m−2 were recorded in grassland. Earthworms were scarce in recently reclaimed sites, but population densities exceeding 200 m−2 were present in older leys. Laboratory, glasshouse and field experiments demonstrated marked effects of earthworms on soil structure and grass growth. Mass loss from Salix litter was retarded by about 20% over a 6-month period when invertebrates were partially excluded. Salix burjatica was sporadically attacked by caterpillars of winter moth (Operophtera brumata (L.)) resulting in severe defoliation and growth check in some years. Salix viminalis was severely damaged by Phratora vulgatissima (L.) (common willow beetle); Salix burjatica was unaffected by willow beetle, which was unable to complete its life cycle on this host. |
