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首页> 外文期刊>Canadian Journal of Forest Research >Predicting the effect of thinning on growth of dense balsam fir stands using a process-based tree growth model
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Predicting the effect of thinning on growth of dense balsam fir stands using a process-based tree growth model

机译：使用基于过程的树木生长模型预测间伐对浓郁香脂杉木林生长的影响

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A tree-level process-based model of forest growth is used to investigate the effects of thinning on the growth of balsam fir (Abies balsamea (L.) Mill.) in stands that have almost reached commercial maturity but that have never been thinned. The model is applied to predict the 20-year growth of a stand following a recently established thinning experiment in which four thinning treatments were tested. The combination of stand properties and treatment type is quite particular and the resulting long-term effect on growth cannot be evaluated based on past experiments. The objectives of the study are to provide estimates of treatment outcome and of their errors over the appropriate time frame for decision making. This is achieved by representing growth processes through functions empirically adjusted to field observations while limiting the inputs of the model to what are usually available through regular forest inventory. Simulations suggest that 20-year growth of individual trees from the smaller diameter classes is improved by the treatments, but the growth of larger trees (>0.1 m(3)) is left unchanged. When the model error is not taken into account, the results after 20 years suggest, with a confidence level greater than 95%, that the merchantable volume of the treated plots does not recover to the level found in the untreated control plots, a result contrary to the initially expected effect of such thinning. By including modelling uncertainty, however, the confidence level associated with such a result is reduced to 70%. Such an inclusion prevents the misuse of the model predictions too far into the future.
机译：在几乎达到商业成熟但从未间伐的林分中，使用基于树级过程的森林生长模型来研究间伐对香脂冷杉（Abies balsamea（L.）Mill。）生长的影响。在最近建立的间伐试验中，该模型用于预测林分20年的增长，该试验对四种间伐处理进行了测试。林分特性和处理类型的结合非常特殊，因此无法根据过去的实验评估对生长的长期影响。该研究的目的是在适当的决策时间内提供治疗结果及其错误的估计。这是通过根据经验调整适应实地观察的函数来表示生长过程，同时将模型的输入限制为通常可通过常规森林清查获得的函数来实现的。模拟表明，通过处理可以改善直径较小类别的单个树木20年的生长，但是较大树木（> 0.1 m（3））的生长保持不变。如果不考虑模型误差，则20年后的结果表明，置信度大于95％，处理过的地块的可销售量不会恢复到未处理的对照地块中的水平。这种减薄的最初预期效果。但是，通过包括建模不确定性，与这种结果相关的置信度降低到70％。这样的包含可以防止模型预测在未来太远的时候被滥用。

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