Aging mistakes and overestimation of productivity for black spruce forests

森林动态、森林管理规划和收获表的特征都是基于年龄-生产力关系(立地质量指数)。然而，以前的研究表明，通过在地面进行年轮计数获得的黑云杉(Picea Mariana)的年龄(通常称为“根领”)并不能给出树木的真实年龄，因为不定根沿着树干的底部发育。成熟时，黑云杉的根系是完全不定的，这意味着最初的根不会随着时间的推移而发展和消失。沿着树干的根的发育在某种程度上隐藏了树木的真实年龄，因为它将生长轮和根颈隐藏在树桩木材和根部之下。由于森林动态的特征和生产力的估计主要取决于树龄，当树龄错误时，这些估计也是错误的，并可能导致管理者做出错误的决定。例如，林分可能比从地面上的年轮计数看起来要老得多，这自动导致生产力高估和错误的管理决策。 本研究项目的主要目的是估计不同条件下生长的黑云杉的老化误差，并利用这些估计来量化生产力高估，并开发产量表和立地指数的修正工具。通过定位隐藏在黑云杉树桩内的发芽日期(真实年龄)，我们将计算出准确的年龄低估和相关的生产力高估。在基本水平上，我们希望确定有利于不定根发育的条件，从而确定增加年龄低估的立地条件。在应用层面上，量化与老化错误相关的生产率高估将为管理者提供更好的数据，以作为其计划决策的基础。

Characterization of forest dynamics, forest management planning and yield tables are all based on age-productivity relationships (site quality indices). However, it was previously shown that age of black spruce (Picea mariana) obtained by a ring count at ground level (commonly referred to as «the root collar») does not give the real age of trees, because of the development of adventitious roots along the base of the stem. At maturity, the root system of black spruce trees is exclusively adventitious, which means that the initial roots do not develop and disappear with time. The development of roots along the stem somewhat «hides» the true age of trees, by concealing growth rings and the root collar into the stump wood and under the roots. Since the characterization of forest dynamics and estimations of productivity mainly lie on the age of trees, when ages are wrong, those estimates are also wrong and can lead to bad decisions by managers. For example, a forest stand could be much older than it appears from a ring count at ground level, which automatically leads to productivity overestimations and erroneous management decisions. The main goal of this research project is to estimate aging mistakes of black spruce growing in different conditions, to use these estimates to quantify productivity overestimations and to develop a correction tool for yield tables and site indices. By locating the germination date (true age) concealed inside black spruce stumps, we will calculate precise age underestimations and associated productivity overestimations. On a fundamental level, we expect to determine conditions favourable to the development of adventitious roots, and hence site conditions that increase age underestimations. On an applied level, the quantification of productivity overestimations associated to aging errors will give managers better data on which to base their planning decisions.