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Mathematical approaches to partition net ecosystem exchange of carbon dioxide in a high-elevation subalpine forest.

机译：在高海拔亚高山森林中划分二氧化碳净生态系统交换的数学方法。

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摘要

Ecosystem-scale gross photosynthesis and total ecosystem respiration are two fundamentally important processes of the terrestrial carbon cycle, but are difficult to quantify and study separately. Two primary objectives of this dissertation are (a) to obtain diurnal estimates of ecosystem-scale photosynthesis and respiration using an isotopic method, and (b) partition components of ecosystem respiration using process-based soil carbon models. Both objectives utilize net ecosystem exchange of CO2 data ( F) and meteorological data collected at a high-elevation subalpine forest (the Niwot Ridge AmeriFlux site).; Data collected during a three month period during late summer 2003 generated isotope flux partitioning estimates of ecosystem-scale photosynthesis and respiration. These partitioning results were compared to an independent flux partitioning routine based on statistical regressions between nighttime F and air temperature. These two methods produced expected diurnal patterns in photosynthesis and respiration. Isotope flux partitioned respiration estimates were not sensitive to air temperature as expected. The difference between the isotopic signatures of net photosynthesis (delta A) and total ecosystem respiration (deltaR) generated from isotope flux partitioning were consistently positive (delta A > deltaR). Values of delta A > deltaR are inconsistent with many other studies, and may result from uncertainties in the ecosystem-scale values of fundamental parameters for the isotope partitioning model. Additionally, delta R is strongly influenced by the linear regression formulas (Model I or Model II regression) utilized to determine delta R from measurements of CO2 and the 13C content in air.; A seven year record of F from the Niwot Ridge site and soil carbon models were used to investigate soil carbon processes. These models were evaluated in how they estimated heterotrophic (microbial) or autotrophic (root) components of ecosystem respiration. Explicit modeling of root dynamics led to better agreement with literature values of the contribution of soil respiration to total ecosystem respiration. However, these models overestimated the autotrophic component of soil respiration when compared to literature values. Hence, additional model development is needed to characterize microbial biomass dynamics.
机译：生态系统规模的总光合作用和总生态系统的呼吸作用是陆地碳循环的两个根本重要过程，但难以单独量化和研究。本文的两个主要目标是：（a）使用同位素方法获得生态系统规模的光合作用和呼吸作用的每日估算值；（b）使用基于过程的土壤碳模型划分生态系统呼吸作用的组成部分。这两个目标都利用了在高海拔亚高山森林（Niwot Ridge AmeriFlux站点）收集的二氧化碳数据（F）和气象数据的净生态系统交换。在2003年夏末的三个月内收集的数据生成了生态系统规模的光合作用和呼吸作用的同位素通量分区估计。根据夜间F和气温之间的统计回归，将这些分配结果与独立的流量分配例程进行比较。这两种方法在光合作用和呼吸作用方面产生了预期的昼夜模式。同位素通量划分的呼吸估计值对空气温度不像预期的那样敏感。同位素通量分配产生的净光合作用的同位素特征（δA）和生态系统总呼吸（δR）之间的差异始终为正（δA>δR）。 ΔA> deltaR的值与许多其他研究不一致，并且可能是由于同位素分配模型的基本参数的生态系统规模值的不确定性导致的。另外，delta R受到线性回归公式（模型I或Model II回归）的强烈影响，该线性回归公式用于通过测量空气中的CO2和13C含量来确定deltaR。来自尼沃特山脊站点的F的七年记录和土壤碳模型用于调查土壤碳过程。对这些模型进行了评估，评估了它们如何估算生态系统呼吸的异养（微生物）或自养（根）成分。根动力学的显式建模导致与土壤呼吸对生态系统总呼吸的贡献的文献价值更好地吻合。但是，与文献值相比，这些模型高估了土壤呼吸的自养成分。因此，需要额外的模型开发来表征微生物生物量动态。

著录项

  • 作者

    Zobitz, John M.;

  • 作者单位

    The University of Utah.;

  • 授予单位 The University of Utah.;
  • 学科 Mathematics.; Environmental Sciences.; Biology Plant Physiology.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 203 p.
  • 总页数 203
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 数学;环境科学基础理论;植物学;
  • 关键词

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