Dynamics of coarse and fine root biomass in eastern species of contrasting silvical characteristics

要准确估计森林生态系统中的碳储量和动态，就需要了解有关根生物量生长和周转的知识。关于地下生物量的特定物种和特定地点的数据非常有限。本研究将对香脂冷杉和糖枫根系的生物量动态和净初级生产量(反映生长和死亡产生的净碳平衡)进行评价。它将侧重于气候和森林管理对树木生物量动态和向树木根系分配碳的影响。它将提供特定物种的数据，从而能够核实目前估算海洋森林地下生物量和碳储量的方法。它将提高模拟气候变化和森林管理做法的潜在影响的能力，这些做法通过移除一些并留下一些腐烂来改变生物量平衡，从而改变树木密度，从而，残存树木的生长条件。由于根系不易测量，因此研究根的生物量动态是困难的。细根的动态将通过对插入土壤的透明管(微管)的图像进行测量，并通过评估和称重从土芯中回收的根来确定。这些方法评估细根的丰度和寿命，从而能够估计其生物量动态。粗根将用压缩空气挖掘，其干生物量将在实验室确定。将开发更容易测量地上特征的估计粗根生物量的公式，并在研究地点之间进行比较。为了确定地下生物量和碳动态的年际变化，将发展一种新的估计粗根净第一性生产力的方法。

Knowledge about root biomass growth and turnover is required to accurately estimate carbon storage and dynamics in forest ecosystems. Species and locale-specific data on belowground biomass is very limited. This research will evaluate biomass dynamics and net primary production (reflecting the net carbon balance resulting from growth and death) of root systems of balsam fir and sugar maple. It will focus on effects of the climate and forest management on biomass dynamics and allocation of carbon to root systems of the trees. It will provide species-specific data enabling verification of current approaches to estimating belowground biomass and carbon stocks of Maritime forests. It will improve the ability to model potential effects of climate change and of forest management practices that alter biomass balance by removing some and leaving some to decay, and that changes tree density and, consequently, growth conditions for residual trees.  Studies of root biomass dynamics are difficult because roots are not easily accessible for measurements.  Dynamics of fine roots will be determined from measurements made on images from transparent tubes (minirhizitrons) inserted into the soil and by evaluating and weighing roots recovered from soil cores.  These methods evaluate the abundance and longevity of fine roots enabling the estimate of their biomass dynamics.  Coarse roots will be excavated with compressed air and their dry biomass will be determined at the laboratory.  Equations for estimating the biomass of coarse roots from easier to measure aboveground characteristics will be developed and compared among the study sites. A new method of estimating net primary productivity of coarse roots will be developed for determining year-to year variation in belowground biomass and carbon dynamics.