Abstract:

Strategic environmental assessment (SEA) involves predicting，evaluating and mitigating the environmental impacts of plans and programs，thereby integrating environmental considerations into strategic decisionmaking.As an environmental appraisal tool，SEA has been more and more widely applied in biodiversity conservation.Current approaches and methodologies of biodiversity impact assessment (BIA) were ineffective，and the assessment results were rather unspecific and incomplete within SEA.In this paper，the limitations of BIA were reviewed and analyzed with specific focuses on four biodiversity levels (landscape，ecosystem，species and gene)，and some evaluating methods were suggested，which was expected to provide the references on the plans and programs，decisionmakers and organizations across a wide range of sectors.For the indices of landscape change measurement were hardly linked with ecological processes on site，it was difficult to predict the biodiversity consequences of landscape changes resulting from developing programs.The key region which was easily reflecting ecological processes (such as biocorridor，protected area，ecotone，“source” and “sink” landscape area) should been focused on landscapelevel impact evaluation.Ecosystem degradation could not be weighed by real value，so the impacts of damaged ecosystem could not be foreseen in accuracy.The assessment of ecosystemlevel impact should provide adequate options to avoid the loss of sensitive and important objectives.In practice，it was impossible to obtain the detailed information in a targeted area for the purpose of BIA，so the specieslevel impact assessment should be addressed through the studies on the key objectives like  protected species，endemic species，economic important species，other genetic resources species，etc.For the phenotype of species could not express the entire genetic traits，it was difficult to measure the impacts on genetic diversity without the experimental data.Currently，the application of genelevel impact assessment was still constrained due to the information gap of gene diversity within populations.

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