Key message

Whole-tree harvesting makes forests more profitable than conventional harvest as long as the impact on tree growth remains under 2.3% for even-aged oak ( Quercus petraea (Matt.) Liebl.) and 3.4% for sweet chestnut ( Castanea sativa Mill.) coppice with oak standards. Coppice-with-standards may have potential to be more profitable than even-aged oak in case of 50% rise in fuelwood prices with 10% decrease in timber prices.

Context

Making the shift to renewable energy sources requires increasing biomass removal from the forest in a sustainable way. Today, the most common practice for forest biomass extraction is whole-tree harvesting rather than conventional harvest in which only stems are harvested or sometimes branches larger than 7 cm in diameter. However, intensive biomass harvesting can certainly increase economic profitability but it could affect long-term forest productivity because more nutrients are exported from sites.

Aims

We explored the land expectation value of even-aged oak (Quercus petraea (Matt.) Liebl.) and sweet chestnut (Castanea sativa Mill.) coppice with oak standards under different discount rates and wood prices scenarios, tree mortality triggered by climate variation as well as the effects of a decrease in forest productivity due to whole-tree harvesting on the land expectation value (LEV).

Methods

We modeled two plausible harvesting scenarios for both stands and assessed their LEV. We first analyzed the sensitivity of the valuation results to discount rate, wood prices changes, and increased tree mortality rates. Second, we compared conventional harvest to whole-tree harvesting in which removing the fine wood implies a decrease in tree growth over the long term (between 1 and 10%).

Results

In the current economic situation, the LEV of even-aged oak is higher than coppice-with-standards but this situation could be reversed in case of rising energy prices and lower timber prices in the future. The variation of the discount rate has a significant impact on the LEV but 3% seems to be adequate for European forests. A gradual increase in annual tree mortality rate of 0.6 and 0.9% along even-aged and CWS rotation, respectively, reduced the LEV by half, while increased mortality with constant rates along the rotations had more negative effect on the LEV than gradual increases: 0.4–0.5% increases in mortality rates reduced both LEV’s by half.

Whole-tree harvesting is able to improve the LEV for both stands by 36 to 64% compared to conventional harvest; but this improvement of LEV only lasts as long as the impact on tree growth remains under 2.3 and 3.4%, respectively, for even-aged oak stand and coppice-with-standards.

Conclusion

Whole-tree harvesting system increases forest profitability as long as the sustainability guidelines for biomass harvesting are respected. With the increased demand for fuelwood, the coppice-with-standards regime may become financially attractive once again and fulfill a multitude of forest owner objectives with a wide range of additional options.

中文翻译：

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评估等龄与标准林分管理的土地期望值以及整棵树采伐对森林生产力和盈利能力的长期影响

关键信息

只要对等龄橡树（ Quercus petraea (Matt.) Liebl.）和甜板栗（ Castanea sativa Mill.）树木生长的影响保持在 2.3% 以下，整棵树采伐使森林比常规采伐更有利可图。符合橡木标准。如果薪材价格上涨 50%，木材价格下降 10%，符合标准的矮树可能比偶龄橡木更有利可图。

语境

转向可再生能源需要以可持续的方式增加森林中的生物质清除。今天，森林生物量提取最常见的做法是整棵树收获，而不是只收获茎或有时直径大于 7 厘米的树枝的传统收获。然而，集约化生物质收获当然可以提高经济盈利能力，但它可能会影响长期的森林​​生产力，因为更多的养分从现场输出。

宗旨

我们探索了等龄橡树（Quercus petraea (Matt.) Liebl.）和甜栗（Castanea sativa Mill.）在不同贴现率和木材价格情景下与橡木标准的矮林的土地期望值，气候变化引发的树木死亡率为以及整棵树采伐导致森林生产力下降对土地期望值 (LEV) 的影响。

方法

我们为两个林分模拟了两种可能的收获场景并评估了它们的 LEV。我们首先分析了估值结果对折现率、木材价格变化和树木死亡率增加的敏感性。其次，我们将传统采伐与整棵树采伐进行了比较，在整棵树采伐中，去除细木意味着树木的长期生长减少（1% 到 10%）。

结果

在目前的经济形势下，偶龄橡木的LEV高于普通橡木，但如果未来能源价格上涨和木材价格下降，这种情况可能会逆转。贴现率的变化对 LEV 有显着影响，但对于欧洲森林来说，3% 似乎就足够了。平均年龄和 CWS 轮作中，树木年死亡率分别逐渐增加 0.6% 和 0.9%，使 LEV 降低了一半，而随着轮作的恒定速率增加的死亡率比逐渐增加对 LEV 的负面影响更大：0.4 –0.5% 的死亡率增加使两个 LEV 降低了一半。

与传统采伐相比，整棵树采伐能够将两个林分的 LEV 提高 36% 至 64%；但是，LEV 的这种改善仅在对树木生长的影响分别保持在 2.3% 和 3.4% 以下时才会持续，对于等龄橡木林分和符合标准的矮林。

结论

只要遵守生物质采伐的可持续性准则，全树采伐系统就可以提高森林盈利能力。随着薪材需求的增加，符合标准的林木制度可能会再次在财务上变得有吸引力，并通过广泛的其他选择来实现众多森林所有者的目标。