Suitability of Long Rotations in Snow Risk Areas : A Stochastic Simulation of Timber Plantations
Suitability of Long Rotations in Snow Risk Areas : A Stochastic Simulation of Timber Plantations
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雪险地区长轮伐的适宜性：人工林的随机模拟
DOI：
10.20659/jfp.3.2_99
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
H. Oka
中科院分区：
文献类型：
--
作者：
H. Kuboyama;M. Amano;H. Oka
在这项研究中，我们评估了雪对日本杉木种植园的损害风险。我们考察了使土地期望值(LEV)最大化的最优轮作年龄(ORA)，以及雪灾的经济影响。我们收集了两种类型的断茎损伤，一种是稀疏型损伤，另一种是多米诺骨牌型损伤。在间伐型的情况下，如果有补贴或更高的价格，长轮伐期是合适的。这是因为支架上的损伤率较低。在多米诺骨牌类型伤害的情况下，ORA类似于没有伤害的情况。降雪风险有两个明显相互矛盾的影响。一种是在林分被雪破坏之前的轮伐期缩短效果。另一种是轮伐期延长效应，即收获较晚才能恢复，雪害的管理成本增加，如果雪害的概率很高，对于成熟的林分来说，较短的轮伐期是有利的，即使在间伐型破坏的情况下也是如此。这与之前研究中的森林火灾情况类似。然而，如果自然雪灾的概率较低，轮伐期缩短效应往往被增加的管理成本的轮伐期延长效应所抵消。此外，如果30岁以上的林分的覆盖率足够低，即使出现多米诺骨牌类型的损坏，ORA也会高于林分或更高的价格。由此可见，老年人的损伤率是决定轮换年龄的关键因素。多米诺骨牌类型伤害后的等级减少量是稀疏型伤害的两倍。在这种情况下，概率多米诺骨牌类型的损害较旧的站在合理的费用，
In this study, we evaluate the risk of snow damage to sugi plantations in Japan. We examine the eptimal rotation age (ORA) which maximizes the land expectation value {LEV) , ancl the economic effects of snow damage. We consiclered two types of stem breaking damage, One is the thinning type and the other is the domino type of damage. In the case of the thinning type, if there are subsidies or higher prices, long rotations are suitable. This is because the damage ratio is Iower in stands. In the case of the domino type damage, the ORA is similar to cases without damage. Snow risk has two apparently contradictory effects. One is a rotation shortening effect harvest before the stand is damaged by snow. The other is a rotation lengthening effect, i.e. harvest later to recover, the increased management costs of snow damage, If the probability of snow damage is high'for matured stands, a shorter rotation is advantageous, even in cases of thinning type damage. This is similar to the case of forest fire in preceding studies. However, if the probability of snow damage is lower for rnature the rotation shortening effect is often cancelled out by the rotation extending effect of increased management costs. Furthermore, if clamage ratios in the stands over 30 years old are sufficiently low, even where there is domino type damage, the ORA is higher than in stands or higher price. From this, it is clear that the damage ratio at older ages is a key factor determining rotation age. The decrease in LEV following domino type damage is twice as much as that of thinning type damage. In cases, probability domino type damage damage older stands to reasonable cost,