INITIAL CONDITIONS, HISTORY AND SUCCESSIONAL PATHWAYS IN 10 CONTRASTING OLD FIELDS

Examined the PCA ordination scores of 10 old fields through 22 yr of succession. Clonal species Dactylis glomerata and Hieracium pratense had the largest correlation with the first principal component in the 1st 18 yr of succession. After 18 yr, Rosa multiflora and Toxicodendron radicans had the largest correlation with the first principal component. Successional pathways show great variation in early succession but variation of pathway decreases later, ie convergence occurs. The greatest difference between groups was in the 1st 8 yr between old fields that had D. glomerata (orchard grass) as a last crop and those that did not. Of common abandonment conditions, last crop greatly influences successional pathways and convergence in these old fields. -from Authors