Belowground biomass dynamic in eastern Canadian forest ecosystems

我正在研究加拿大东部以香脂冷杉或糖枫为主的森林根系生物量的长期波动。它们粗大的根代表了它们生物量的一个大而持久的部分。另一方面，细小的吸收根构成了不断翻转的生物量。细根不能维持很长时间，必须补充。粗根的生长，特别是垂死的细根的替换消耗了树木的大部分固定碳(C)。这些投资反映了大气中游离二氧化碳的数量，以及呼吸作用和死根腐烂释放的碳。通过估算根系产量和死亡率的变化，我的研究为模拟地球生态系统的碳循环提供了重要的输入。这些模型预测大气中二氧化碳浓度的变化以及由此导致的气候变化。我挖掘粗根以确定其生物量，但我寻找其他树木特征，其测量可以以可接受的精度预测粗根生物量。我通过放置在土壤中的透明管（微型电子管）用相机观察细根。根据根系出现、消失和大小的时间，我估计细根生物量随时间的变化。我使用这种方法来研究被研究物种之间细根动态的差异，并确定树木老化对地下生产力和生物量的影响。我还将用它来研究疏林和伐木对地下生物量的影响。这些处理从根本上改变了森林地点的条件，并在根和树桩中留下了大量的死亡生物量。然而，它们也提高了剩余树木的生产力，并且通过在采伐地点更新植被，为恢复生产力创造了条件。我的研究将为规划森林作业提供有用的数据，以最大限度地从大气中去除二氧化碳，并减少其从森林生态系统中的释放。因此，我的研究可以通过选择有效的森林管理方法来增加减少大气中二氧化碳浓度的选择。

I am studying long-time fluctuations in biomass of roots of eastern Canadian forests dominated by balsam fir or sugar maple. Their coarse roots represent a large, long-lasting portion of their biomass. The fine, absorbing roots, on the other hand, constitute a continually turning over biomass. The fine roots do not last long and must be replenished. Growth of coarse roots and, particularly, the replacement of dying fine roots cost trees much of their fixed carbon (C). These investments reflect on the amount of free CO2 in the atmosphere, as does the release of C from respiration and decay of dead roots. By estimating variation in production and mortality of the roots, my studies provide an important input to modeling C cycling of Earth's ecosystems. Such models predict changes in atmospheric CO2 concentrations and the resultant change of climate. I excavate coarse roots to determine their biomass but I look for other tree characteristics whose measurement can predict coarse root biomass with acceptable accuracy. I study fine roots by observing them with a camera through transparent tubes (minirhizotrons) placed in the soil. Based on the time of appearance, disappearance, and size of the roots, I estimate changes in fine root biomass over time. I use this approach to study differences in fine root dynamics between the studied species and to determine effects of tree aging on belowground productivity and biomass. I will also use it to study effects of thinning and logging on belowground biomass. These treatments radically change conditions at forest sites and leave large amounts of dead biomass in roots and stumps. However, they also increase productivity of residual trees and, from renewal of vegetation at harvested sites, create conditions for renewed productivity. My studies will provide data useful for planning forest operations to maximize the removal of CO2 from the atmosphere and to reduce its release from forest ecosystems. Hence, my studies may add to options for reducing concentrations of atmospheric CO2 by choosing effective methods of forest management.