남부지역 편백 인공림 내 천연갱신 치수의 생육 특성

정상훈1*, 이상태1, 강성기2

(1국립산림과학원 산림기술경영연구소, 2산림교육원)

Growth Characteristics of Natural Regeneration Seedlings in Artificial Chamaecyparis obtusa Forests in the Southern Region

Sang Hoon Chung1*, Sang tae Lee1, Sung Kee Kang2

(1Forest Technology and Management Research Center, National Institute of Forest Science,

2Forest Disaster Management Training Division, Forest Training Institute))

요약: 본 연구는 천연갱신을 통한 편백 후계림 조성 가능성을 알아보고자 무주, 거제, 진주에 위치한 천연갱신 치수 생육지 37개소를 대상으로 연구를 수행하였다. 상층의 임분밀도는 384∼1,373그루/ha, 임령은 3∼10영급, 평균 수고는 13.1∼20.9m이었다. 천연갱신 치수밀도는 1,234∼68,083그루/ha이었고 치수가 분포하지 않는 곳도 조사되었다. 편백 치수밀도를 5단계(20천그루 초과, 10천～20천그루, 5천～10천그루, 5천그루 미만/ha, 없음)로 구분하여 치수의 생육환경을 분석한 결과, 갱신치수가 가장 많은 임분은 2017년 열식간벌이 시행된 4영급 임분으로 치수밀도는 68,083그루/ha(평균 근원경: 4.0mm, 평균 치수고: 53cm)이었으며, 상층 편백의 임분밀도가 ha당 850그루로 높았음에도 불구하고 대상지 중 수관울폐도는 56.0%로 가장 낮았다. 반면, 숲가꾸기를 실시하지 않아 수관울폐도가 93.0%로 가장 높은 임분(임분밀도: 1,275그루/ha)에서는 천연갱신 치수가 발견되지 않았다. 솎아베기와 같은 임분 내 교란활동 초기에는 편백 치수 발생에 긍정적 효과를 나타내지만, 하층식생 및 수관층 발달로 인해 치수 생존에 불리한 생육환경이 형성되는 것으로 파악되었다.

Abstract: This study was carried out in order to confirm the possibility of the secondary growth forest composition in plantation forests of Chamaecyparis obtusa where naturally regenerated seedlings are growing in the soutnern region. The average stand density of the upper layer was 384∼1,373 trees/ha, the age-class was III∼X, and the average tree height was 13.1∼20.9m. The density of C. obtusa natural seedlings was 1,234∼68,083 seedlings/ha, and there were places where seedlings were not distributed. The analysis of the growth characteristics was divided by classifying the seedling density into five stages (20,000 over, 10,000～20,000, 5,000～10,000, less than 5,000 seedlings/ha, and none). The stand with the largest number of seedlings was the IV age-class stand where row thinning was implemented in 2017, and the density of natural seedlings was 68,083 seedlings/ha (ave. of diameter at root; 4.0 mm, ave. of height; 53 cm). Despite the high stand density of 850 trees/ha for upper layer, the degree of canopy closure was the lowest at 56 % among the sites. On the other hand, no natural seedlings were found in the stand (density; 1,275 trees/ha) with the highest degree of canopy closure (93 %) due to no thinning. The disturbance activities, such as thinning, initially have a beneficial effect on the emergence of natural seedlings. However, it has been observed that the subsequent development of understorey vegetation and canopy layers creates a growth environment that is increasingly unfavorable for the seedling survival.

Keywords : Chamaecyparis obtusa, Natural regeneration, Seedling, Seedling growth, Thinning