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的碳储量和动态，需要了解根系生物量的生长和周转。关于地下生物量的物种和特定地点的数据非常有限。本研究将评估香脂冷杉和糖枫根系生物量动态和净初级生产量（反映生长和死亡导致的净碳平衡）。它将侧重于气候和森林管理对生物量动态和碳分配到树木根系的影响。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，这些做法通过去除一些和留下一些腐烂来改变生物量平衡，从而改变树木密度，从而改变剩余树木的生长条件。根系生物量动态的研究是困难的，因为根系不容易测量。细根的动态将通过对插入土壤的透明管（微型根管）的图像进行测量，并通过评估和称重从土壤芯中回收的根来确定。这些方法可以评估细根的丰度和寿命，从而估算其生物量动态。粗根将用压缩空气挖掘，其干生物量将在实验室测定。将建立从较容易测量的地上性状估算粗根生物量的公式，并在研究点之间进行比较。为确定地下生物量和碳动态的年际变化，将开发一种估算粗根净初级生产力的新方法。

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.