Long-term development of fish populations in the Římov Reservoir

Abstract  The inshore fish community of the Římov Reservoir in the Czech Republic was evaluated over 21 years using shore seining at night. The development of the fish community was divided into two separate phases: a highly dynamic and unstable phase dominated by perch, Perca fluviatilis L., was replaced by an extremely stable cyprinid phase dominated by roach, Rutilus rutilus (L.), and bream, Abramis brama (L.). The abundance of both these species oscillated during the cyprinid phase, but with decreasing amplitude. The proportion of piscivorous fish species such as asp, Aspius aspius (L.), pike, Esox lucius L., and pikeperch, Sander lucioperca (L.), increased slightly with time but remained low. The biomass of large Cladocera was negatively correlated with fish biomass only during the perch phase. The Shannon–Weaver index of diversity increased during the fish community succession, mainly because of greater evenness amongst the species.     

不同蠹害区的蠹害木清理试验

在松纵坑切梢小蠹的综合防治中,蠹害木的清理是一重要环节。依据在轻、中、重受蠹害云南松林区进行的蠹害木清理试验结果,一般情况下,对轻度受害区即被害株率在10%以下,蠹害指数在5以下,清理蠹害木应控制在1.00%;对中度受害区,即被害株率在10%～50%,蠹害指数在5～15,清理蠹害木应控制在10.00%左右;重度受害区,即被害株率在50%以上,蠹害指数在15以上,清理蠹害木应控制在20.00%左右。在重度受害区,除清理蠹害木外,还需辅以其他措施,进行综合治理才能有效控制蠹害。