Kształtowanie się wysokości upraw dębowych w centrum i na obrzeżu gniazd na siedlisku lasu mieszanego świeżego

The Polish forest gap trials report oaks height in the middle of a gap or average height of all oaks in the gap. To decide when the shelter of surrounding old trees in no longer needed and old trees between gaps can be cut, a forester should have knowledge how oaks grow in the peripheral part of gaps. In the experiment height of planted oaks in the age from 5 to 11 years growing in 15 are gaps on fresh mixed broad−leaved forest site was measured. The smallest difference in height of oaks growing in the middle and in the peripheral part of gaps was observed for 5−year−old oaks. The difference became bigger as oaks became older. For oaks older than 8 years, saplings in the peripheral parts are on average 40% lower than those in the central part. The height of older oaks in the middle and in the southern periphery of gap was less differentiated than of oaks growing in northern, eastern and western peripheral parts. Large differences in height can provoke oaks to develop bad stem forms (e.g. forked, thick branched). Special care should be taken during pre−commercial thinning to eliminate oaks with bad stems in the peripheral parts of gaps.