نقش خشكه دارها در تجديد حيات طبيعي توده هاي جنگلي (مطالعه موردي : بخش چيلر جنگل خيرودكنار نوشهر)

Impact of dead trees on natural regeneration in forest stands (Chelir district, Kheiroudkenar, Nowshahr).

The main objective of this study which was conducted in an intact stand of the experimental Kheiroudkenar forest (Chelir district), was to examine the ecological importance of dead trees followed by itʹs impact on natural regeneration of the forest. In this study the seedlings around dead trees were recorded in a 50 ha stand, where the dead trees were divided into four decay classes. Considering the decay classes, results indicated that; there were different kinds of establishment of regeneration. The highest numbers of seedlings were accounted around dead trees classified in 3rd decay class, while 4, 2 and 1 decay classes were in the next orders. Gap opening related to dead trees had important effects on establishment of the regeneration. Results showed that with increasing of decay classes, size of gaps decreased. In this study gaps were divided into five groups, including close gap (closed canopy), very small (0-12.5 m^2), small (12.5-50 m^2), medium size gap (50-113 m^2) and large size or open canopy (>113 m^2). Abundance of seedlings under the closed gaps of stand crown was maximum, while the numbers of seedlings were reduced under the medium gap size, very small, small and large size, respectively. One way analysis of variance showed that there was no significant difference (at 5% significant level) among the number of seedlings around dead trees with different decay classes, however there was a significant difference among abundance of seedlings under different gap sizes, produced by dead trees. Therefore, gap opening caused by dead trees, had higher effect on establishment of regeneration than decay classes.