IRCEB: Measuring and Modeling the Effects of Fire on the Structure and Function of Boreal Forests in North America

量化干扰和随后的演替过程对陆地表面和大气之间的能量、水和养分交换的影响是生态学许多学科的核心。随着人口的增加和干扰频率的增加，这类研究的重要性只会增加。北方森林是世界上第二大森林生物群，土壤和植被中的碳含量与大气中的碳含量大致相同。然而，每年大约有500万公顷的北方森林被烧毁，近年来这一价值超过了150万公顷。对火灾对北方森林结构和功能的影响还不存在机械性的理解，甚至禁止使用生态系统过程模型来量化火灾对北方森林碳收支的影响。这个项目有三个主要目标。第一个是量化野火对加拿大马尼托巴省北部演替的北方黑云杉林小气候、结构和功能的影响，并将这些结果与其他北方森林年龄序列研究进行比较。这项研究将使用综合的生态生理、生物地球化学、同位素和微气象野外测量来提高对个体过程在演替过程中变化的理解，并利用涡流方法来量化黑云杉生态系统与大气在火灾后的演替过程中如何进行全系统能量、水和二氧化碳的交换。这套测量数据将在七个不同树龄的黑云杉林中重复进行，这些林分组成了一个分布在马尼托巴省的弧形序列。第二个目标是使用当前和未来的卫星传感器来量化北美北部森林野火的现行和过去的空中范围，并确定是否可以检测到最近干扰的森林中因土壤温度变暖而导致的植被提前生长季节变绿的假设。第三个目标将使用两个陆地生态系统模型(IBIS和TEM)和从卫星传感器获得的空间上明确的火势范围值，以研究火灾对北美北部针叶林与大气之间二氧化碳交换的可能影响。模型模拟将在一定的时间和空间尺度上与现场数据进行比较。这项拟议的研究符合IRCEB项目的资格，因为(1)它使用以前研究期间进行的和正在进行的实地测量来解决一个关键的和未得到回答的生态问题，(2)它使用来自许多学科(生态生理学、生态系统生态学、气象学、土壤、地球科学、景观生态学、大气科学和全球生态学)的互补测量来解决与全球碳循环有关的生态学中的基本问题，(3)它采用了一套测量方法，能够同时确定干扰对个人碳循环过程和整个生态系统净交换的影响，这将提供标准化的、独立的NEE估计，(4)它与其他科学家建立了关键的联系，这些科学家测量了火灾对北方森林碳收支某些组成部分的影响，这些森林的气候、主要植被和永久冻土的重要性截然不同，(5)它与创造历史火灾记录和监测当前火灾状况的科学家建立了合作，(6)它有助于为土地管理人员制定和实施火灾缓解战略，(7)它将促进北方生态学本科生和研究生的培训，并向纳尔逊房子第一民族印第安人提供非常需要的基本森林生态学和管理培训。

0077881GowerQuantifying the effects of disturbance and subsequent successional processes on the exchange of energy, water and nutrients between the land surface and atmosphere is central to many disciplines in ecology. The importance of such studies will only increase as the human population increases and disturbances increase in frequency. Boreal forests are the second largest forest biome in the world and contain approximately the same amount of carbon in the sols and vegetation as carbon in the atmosphere. About 5 million hectares of boreal forest burn each year, however, and in recent years this value exceeded 1.5 million hectares. A mechanistic understanding of the effects of fire on the structure and function of boreal forests does not exist, prohibiting even a precursory use of ecosystem process models to quantify the effects of fire on the carbon budget of boreal forests. This project has three major objectives. The first is to quantify the effects of wildfires on the microclimate, structure and function of successional boreal black spruce forests in northern Manitoba, Canada, and compare these results to other boreal forest age-sequence studies. This study will use integrated ecophysiological, biogeochemical, isotopic, and micrometeorological field measurements to improve understanding of how individual processes change during succession, and the eddy flux approach to quantify how whole-system energy, water and CO2 exchange between a black spruce ecosystem and the atmosphere change during succession following fire. The suite of measurements will be replicated in seven different-aged black spruce stands comprising an are sequence distributed across Manitoba. The second objective is to quantify active and past aerial extent of wildfires for North American boreal forests using current and future satellite-borne sensors, and determine if hypothesized earlier growing season green-up by vegetation caused by warmer soil temperature in recently disturbed forest can be detected. The third objective will use two terrestrial ecosystem models (IBIS and TEM) and spatially explicit fire extent values obtained from satellite-borne sensors to examine the possible effects of fire on exchange of CO2 between the North American boreal forest and the atmosphere. Model simulations will be compared to field data at a range of temporal and spatial scales. The proposed study qualifies as an IRCEB project because (1) it uses past and ongoing field measurements made during previous studies to address a critical and unanswered ecological question, (2) it uses complementary measurements form many disciplines (ecophysiology, ecosystem ecology, meteorology, soils, geosciences, landscape ecology, atmospheric science, and global ecology) to address a fundamental question in ecology that is relevant to global carbon cycles, (3) it employs a suite of measurements that will enable the simultaneous determination of the effects of disturbance on individual carbon cycling processes and whole ecosystem net exchange which will provide standardized, independent estimates of NEE, (4) it establishes critical linkages with other scientists measuring the effects of fire on select components of the carbon budgets in boreal forests of contrasting climate, dominant vegetation and the importance of permafrost, (5) it establishes collaboration with scientists creating historic fire record and monitoring current fire status, (6) it contributes to the development and implementation of fire mitigation strategies for land managers, and (7) it will facilitate the training of undergraduate and graduate students in boreal ecology, and provide very badly needed basic forest ecology and management training to the Nelson House First Nation Cree Indians.