ABSTRACT

The influence of thinning on growth, development, and yield of a spruce understory and a pine overstory was examined based on an experiment including five stands in southern Finland. Two thinning intensities (regular and heavy) were applied to the pine overstory. They were combined with four treatments in the spruce understory: total removal, retention of 800 and 1600 stems ha⁻¹, and untreated. The plots were remeasured at 5-year intervals during the monitoring period of 10–15 years. The results indicated that thinning of the pine overstory significantly promoted the diameter growth of the spruce understory trees throughout the 10–15-year study period without notable delay, and height growth with a substantial lag during the first 5-year period. The influence was swifter and greater with heavier thinning. Thinning of the understory did not influence the height growth of the dominant understory spruces or the growth of the overstory. Complete removal of the understory resulted did not consistently influence growth of the overstory. It was concluded that a spruce understory seemed to thrive and grow relatively well under an overstory of pine, but repeated thinnings in the overstory were required to sustain understory vitality and growth in a prolonged two-storied situation.

摘要

根据包括芬兰南部五个林分在内的实验，研究了间伐对云杉林下林木和松树林上林木生长、发育和产量的影响。对松树覆盖层应用了两种疏伐强度（常规和重度）。它们与云杉林下的四种处理相结合：完全去除，保留 800 和 1600 茎公顷^-1，且未经处理。在 10-15 年的监测期内，每隔 5 年对这些地块进行重新测量。结果表明，在整个 10-15 年的研究期间，松树上层间伐显着促进了云杉林下林木的直径增长，而没有明显延迟，而在前 5 年期间，高度增长明显滞后。随着更重的变薄，影响更快、更大。林下间伐不影响主要林下云杉的高度生长或上层林的生长。完全移除林下层并不会持续影响上层林的生长。得出的结论是，云杉林下层似乎在松树上层林下茁壮成长，生长得相对较好，