间伐对日本黑松海岸林更新的影响

为弄清间伐对海岸林内环境因子 ,进而对海岸林天然更新的影响 ,在黑松海岸林内进行了 4种不同强度的块状间伐试验 .林分间伐后 ,对更新状况和环境因子进行了连续观测 .结果表明 ,间伐可以改善林内光环境、提高土壤的含水量、加强空气流动、促进枯枝落叶的分解等 .4 0年生的黑松海岸林 5 0 %间伐处理后 (密度为 15 0 0株·hm-2 ,林冠开阔度 >30 % )不会对海岸林本身造成风害 ,也不会对防护功能产生较大影响 ,但却能为黑松海岸林天然更新提供良好的生态环境 .试验结果证实了间伐产生的林隙内日本黑松的更新规律 ,提出间伐可作为同龄黑松海岸林向复层、异龄海岸林演化的主要经营措施 .

Influence of thinning on regeneration in a coastal Pinus thunbergii forest

A coastal forest planted nearby the sea can provide many shelter benefits for the coastal regions. It is ideally if the continuity of the shelter benefits could be preserved through reasonable management. Thinning and regeneration as the most important management techniques for plantations can help the continuity of the shelter benefits of the coastal forest. However, because of the peculiarities of coastal forest, i.e., the coastal plantation nearby the sea is vulnerable to disturbances (thinning as one kind of disturbance), the study on thinning and regeneration within a coastal forest is poorly understood. The purpose of this paper is to give a primary understanding in natural regeneration for the coastal Pinus thunbergii forest with different thinning rates after four growing seasons since thinning. The experiment was carried out at the middle of the shoreline along the Japan Sea, and the investigated sites consisted of four thinning treatments (control, 0% thinned, 20% thinned, 30% thinned and 50% thinned) in a coastal P. thunbergii forest. After thinning, the regenerated seedlings, soil water content, light condition (canopy openness or canopy density), wind regime, and litter depth and quantity were investigated for four growing seasons. The relationships between the regenerated seedlings and light condition, litter, wind profile and soil water content were examined. The results showed that thinning could improve the light condition on the forest floor, increase the exchange of airflow (wind speed) in the coastal forest stand, and ameliorate the water content of the forest soil. These factors accelerated the decomposition of litters, and provided necessary conditions for natural regeneration. The results of regeneration observation indicated that the most intensively thinned treatment (50% thinned with density of about 1500 stems.hm-2) could provide a better condition for regeneration during the four growing seasons. The density and growth of seedling (greater than 1 year) increased significantly with increasing thinning intensities, and the establishment of seedlings was obviously succeeded in the most intensively thinned treatment, but failed in less thinned treatments and understory. The thinned intensity of 50% did not induce wind damage to the coastal forest in the four years after thinning, and did not cause the loss of shelter functions of the coastal forest such as sand blocking, wind breaking and salt preventing etc.. On the contrary, it could provide the suitable conditions for natural regeneration of the pine coastal forest, or for the immigration of other species. Therefore, thinning as the silviculturally created openness is very important for the establishment of seedlings in the coastal forests, which provides a mechanism for the coastal forest from even aged stands dominated by P. thunbergii to stands containing multiple size classes and canopy layers.