| Forest pests destroy not only forest resources, but also forest ecosystem. In a general way, the direct loss caused by pests is involved with stumpages and forest productions. The indirect loss includes several facets about ecology and society. Based on summarized existing theories of calamities evaluation and thorough investigation, the new technical flow of calamities evaluation caused by forest pests has been worked out and the calculating mode for direct loss has been founded. According to these research achievements, the direct economic losses caused by forest pests added up to 11.98 billion RMB annually from 1996 to 2000. Especially, the pests occurred area reached 766×104hm2, the direct economic losses was 14.47 billion RMB in 1999. Otherwise, using the relation of the accumulation of biomass and environment resources value, the estimate method of the losses of ecology benefit has been built.
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