Succession of the Slope Vegetation of Expressways (II)

要旨

In the first reports was discussed a reconnaissance method of vegetation survey for the diagnostic study of succession of the slope vegetation on expressways. In that case study were found many types of communities on various successional stages.This time the author plan to ellaborate on a quadrate method for the judgement of successional stages of these many types grass slope vegetation.He made a case study on Meishin expressway, Tomei expressway, and Chuo expressway. Selection of stands for sampling was done for each typical communities. Size of sampling area is about 4-25 m2, where is a enough area for the sampling plot of grassland and scrub communities.Data were recorded according to Braun-Blanquet method. The number of data was 226 plots. The analysis of the data for the diagnosis of succession was made as follows.1. The data were classified into 8 communities (Meishin), 6 (Tomei), and 5 (Chuo). The floristic composition in each roads were compared.2. The comparison of life-form spectra of each roads and each communities was done.3. The number of degree of succession was calculated for each roads and each communities.After these comparison, the results of diagnosis is: Meishin (13 years after construction) is the most progressive stages of succession, next is Tomei (8 years), and Chuo (4 years) is the last.The sere was presumed after the results of floristic composition, life-form spectra, degree of succession, and index of similarities of each communities. The author presumed 4 sere, 2 were orthosere and 2 were plagiosere. Pueraria lobata and Robinia pseudo-Acacia made plagiosere, which do not progress normally to the climax but stagnate in their stages.

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