Collaborative Research: Thresholds and mechanisms of net ecosystem production (NEP) resilience following moderate disturbance: Why does one ecosystem recover and another one crash?

合作研究：中度干扰后生态系统净生产（NEP）恢复力的阈值和机制：为什么一个生态系统恢复而另一个生态系统崩溃？

• 批准号: 1655095
• 负责人: Christopher Gough
• 金额: $ 80万
• 依托单位: Virginia Commonwealth University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1655095&HistoricalAwards=false
• 关键词: Collaborative; Research; Thresholds; mechanisms; net

Forests of the United States are primary sources of food, fiber and energy. They play a fundamental role in the earth's climate system by sequestering in plant biomass carbon that might otherwise form the molecular backbone of atmospheric greenhouse gases such as carbon dioxide. Forests' capacity to capture atmospheric carbon dioxide and build biomass may change substantially with age and disturbance. Scientists have long theorized a decline in growth and carbon uptake as forests age. New observations, however, suggest that low levels of disturbance, such as those originating from insect pests, fungal pathogens, and extreme weather, in aging forests may, counter-intuitively, sustain or even increase forest carbon sequestration and growth. The mechanisms underlying these higher-than-expected rates of forest carbon sequestration are unknown. This study seeks to identify the mechanisms underpinning forest growth resilience to disturbance, and their thresholds. The researchers will also evaluate if, how, and why different computer simulations, critical to predicting future forest carbon storage and growth and yield, fail to replicate this resilience. Furthermore, they will determine whether evergreen forests in the western United States and deciduous forests in the East, with different prevailing disturbance regimes and climates, follow unique age-forest growth trajectories. The benefits of this project to society, forest and land managers, grade school educators, university students, and forest scientists are far-reaching. By combining biologically-informed field and simulation experiments with a synthesis of North American forests, this study will significantly advance our ecological thinking about forest disturbance, while producing results immediately relevant and accessible to ecosystem and earth system simulations, and to forest managers working to maximize carbon storage, growth, and timber production in increasingly disturbed forest landscapes. The project will produce openly available instructional materials for grade school teachers, train several graduate and undergraduate students, provide open and transparent sources of data and computer code to scientists and land managers, and form a student training partnership between a United States Department of Energy laboratory and an academic institution.  The future terrestrial carbon sink is uncertain as forests of the United States upper Midwest and east broadly advance from early to middle forest succession. With this transition, early successional canopy dominants are senescing and giving way to more biologically and structurally complex forests that are increasingly subject to moderate severity disturbance. Recent studies suggest that net primary production may be sustained in such forests at higher-than-expected rates, but the limits of and mechanisms behind such functional resilience cannot be predicted from present knowledge, which is derived almost entirely from studies of severe, stand-replacing disturbance dynamics in recently disturbed forests. Ecosystem and global models, developed from the same intellectual foundations, also have trouble reproducing the effects of moderate disturbances. The three core research objectives of this work are to: 1) identify mechanisms supporting net primary production resilience to disturbance, and their thresholds; understand if, how, and why different forest models fail to replicate this NPP resilience; and 3) elucidate whether temperate deciduous and coniferous forests, with different disturbance regimes and climates, follow unique age-production trajectories. The project uses a 3-pronged approach of field experiments, model testing, and large-scale data synthesis to transform understanding of how resilient the carbon cycle will be to a range of moderate disturbance intensities in aging forests, elucidating the underlying mechanisms that determine the threshold between net primary production resilience and decline. The field component uses a fully replicated gradient of disturbance severity, from 0 to 85 % defoliation, to systematically determine how and why the carbon cycle shifts in response to rising disturbance levels. The PIs will employ a suite of carbon and nitrogen cycling measurements, focusing on canopy structure, leaf physiology, and canopy nitrogen reallocation, to identify the mechanisms that cause rapid net primary production resilience or decline following disturbance. The modeling component of the project uses data assimilation experiments, running two very different ecophysiological models within an open source, NSF-supported ecoinformatics toolbox, to identify the processes most responsible for the models' hypothesized failure to simulate net primary production resilience to disturbance, and iteratively inform the next field season's sampling priorities. Finally, a data synthesis component uses newly available observations to characterize disturbance effects on age-net ecosystem production trajectories for North American's temperate forests.

它们的森林是食物的主要来源，它们在地球的气候系统中起着基本作用，它可以隔离n植物生物量碳，这可能形成大气温室气体气体的分子骨架，例如二氧化碳的能力。并建立生物量可能会随着年龄的增长和碳的吸收而发生大幅变化。森林固结是未知的。东方的落叶室是独特的增长轨迹。美国S，这项研究将对生态系统和地球系统模拟的一些森林干扰，以最大化碳存储，并在越来越多的森林景观中产生木材。对于美国能源实验室和和和和和and和and和and和and Andan Demic Institute之间的科学家，并在美国上西部和东百叶片的森林中尚不确定在森林中，具有最佳的森林冠军是在诱人的和结构上的森林中陷入困境的森林。目前的知识是从最近的森林和全球智力基础中进行严重的，重新置换的干扰动力学的研究。 ST模型无法复制这3）阐明温带落叶和针叶性森林是否遵循独特的年龄生产轨迹，该项目使用了3条派遣的方法。关于碳周期在牙龈森林中的一系列中等干扰强度，使基本机制的净产量固定在0到85％的净产量启动与下降之间的趋势。碳循环对扰动的响应响应。工具箱，确定最负责模型的过程，以模拟净初级生产有韧性，以使下一个野外季节的先验炎进行迭代。

项目成果

Collar Properties and Measurement Time Confer Minimal Bias Overall on Annual Soil Respiration Estimates in a Global Database

• DOI: 10.1029/2020jg006066
• 发表时间: 2020-11
• 期刊: Journal of Geophysical Research: Biogeosciences
• 作者: J. Jian;C. Gough;D. Sihi;A. Hopple;B. Bond‐Lamberty

Inferring the effects of partial defoliation on the carbon cycle from forest structure: challenges and opportunities

从森林结构推断部分落叶对碳循环的影响：挑战与机遇

• DOI: 10.1088/1748-9326/ac46e9
• 发表时间: 2022
• 期刊: Environmental Research Letters
• 影响因子: 6.7
• 作者: Gough, Christopher M;Foster, Jane R;Bond-Lamberty, Ben;Tallant, Jason M
• 通讯作者: Tallant, Jason M

Mapping Temperate Forest Phenology Using Tower, UAV, and Ground-Based Sensors

• DOI: 10.3390/drones4030056
• 发表时间: 2020-09
• 期刊: Drones
• 影响因子: 4.8
• 作者: J. Atkins;A. Stovall;Xi Yang

Mechanistically-grounded pathways connect remotely sensed canopy structure to soil respiration

机械接地路径将遥感冠层结构与土壤呼吸连接起来

• DOI: 10.1016/j.scitotenv.2022.158267
• 发表时间: 2022
• 期刊: Science of The Total Environment
• 影响因子: 9.8
• 作者: Hickey, Laura J.;Nave, Lucas E.;Nadelhoffer, Knute J.;Clay, Cameron;Marini, Alexandra I.;Gough, Christopher M.
• 通讯作者: Gough, Christopher M.

Structure and parameter uncertainty in centennial projections of forest community structure and carbon cycling

森林群落结构和碳循环百年预测的结构和参数不确定性

• DOI: 10.1111/gcb.15164
• 发表时间: 2020
• 期刊: Global Change Biology
• 影响因子: 11.6
• 作者: Shiklomanov, Alexey N.;Bond‐Lamberty, Ben;Atkins, Jeff W.;Gough, Christopher M.
• 通讯作者: Gough, Christopher M.