Several indices assessing landscape dispersion, such as isolation, type divergence and nearest neighbor index, were compared. Different indices could reflect different aspects of landscape dispersion. Dispersion index was suggested to assess the dispersion more comprehensively. All the indices were computed to study the landscape dispersion in a valley basin, and the results showed that dispersion index was better to synthesize information and to be in line with practice than others.
Advances in the research of weeds and crops competition model are summarized in three parts : 1.establishment of the empirical models. 2. the dynamic simulation models. 3. the application of the researches in weed management. And the research directions are also advised.
