Effects of clearcutting on the tree species composition, structure, and diversity of a mixed broadleaf-Korean pine (Pinus koraiensis) forest on Changbai Mountain: implications for ecosystem restoration.

Large areas of primary mixed broadleaf-Korean pine forests on Changbai Mt., on the border between China and North Korean have been replaced by secondary forests through clearcuting since the 1950s. How clearcutting impacts the mixed forest ecosystem still remains unclear. We compared the tree species composition, structure, and diversity of a primary and a secondary forest that had suffered clearcutting, 30 yr. previously. Results showed that the mean basal area of trees (≥10 cm diameter at breast height (DBH)) was markedly lower in the secondary forest than in the primary forest, whereas the density of seedlings (＜2 cm DBH, ≥50 cm tall), saplings (2~9.9 cm DBH), and trees were all significantly higher in the former. Values for the species richness and both Simpson's and Shannon's diversity indices for seedlings and saplings were greater in the secondary forest than in the primary forest, but the values of these 3 indices for trees were significantly lower in the former. These results indicate that clearcutting altered the forest structure by significantly decreasing the basal area of trees and increasing the numbers of seedlings and saplings. It also altered the species composition with the secondary forest having more pioneer species than the primary forest. The secondary forest has higher species diversity and abundant climax species of seedlings and saplings, and this potentially favorable situation offers an opportunity to develop restoration plans.