Collaborative Research: NSFDEB-NERC: Tropical deadwood carbon fluxes: Improving carbon models by incorporating termites and microbes

合作研究：NSFDEB-NERC：热带枯木碳通量：通过结合白蚁和微生物改进碳模型

• 批准号: 2149151
• 负责人: Amy Zanne
• 金额: $ 53.89万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2023-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2149151&HistoricalAwards=false
• 关键词: Collaborative; Research; NSFDEB; NERC; Tropical

One of the largest biological reservoirs of carbon is in the wood of forest trees. Once trees die, wood-containing carbon is consumed by organisms such as microbes and insects. Such carbon can be emitted into the atmosphere as carbon dioxide or methane gas. Additionally, only some microbes can break down lignin, a critical building block of wood. When they are unable to do so, remaining lignin gets locked in soil. The tropics have vast stores of carbon in trees but little is known about where that carbon ends up. Both microbes and termites consume tropical wood, but which one does the job alters how fast and in what form carbon is released. Typically, microbes need lots of moisture to thrive on wood, but termites may require less since they can hide in their nest mounds and store water if it becomes too dry. Scientists have been trying to model global carbon cycling under environmental change, but they have yet to include the decay of wood by microbes and insects in their studies. The researchers on this study predict that these organisms have an enormous impact on global carbon cycling. The experimental field work will cut across ecosystems with varying rainfall in Queensland, Australia, from wet rainforest to dry savanna. At these different sites, the researchers will compare how fast termites versus microbes consume the wood and what gases are released during wet and dry seasons. The results will be incorporated into computer models to determine how termites and microbes affect carbon cycling at regional to global scales. Such information will be fed back to the scientific community to make better predictions about the global carbon cycle. This project is an international collaboration between scientists in the U.S., the U.K. and Australia, and is supported, in part, by the NSF Office of International Science and Engineering. Additionally, workshops will bring together project scientists with forestry stakeholders to develop potential strategies for preventing the decay of carbon in wood, and reducing natural carbon emissions. The project will also support education and training of junior scientists. Three questions will be addressed in this project: Q1. What controls rates of coarse wood debris carbon turnover? Turnover rates will be determined by measuring termite and microbe activity, which are dependent on climate and wood construction. Wetter conditions should increase turnover, but termites should increase turnover relatively more in dry conditions due to their water conservation strategies. Dense, highly lignified wood should decay more slowly. Q2. What controls fates of carbon liberated from coarse wood debris? Carbon fates (carbon dioxide, methane, soil organic residues) will depend on the stage of wood decay and the composition of termite and microbial communities. Later stages of decay, increased abundance or activity of methanogenic archaea, (or decreased bacterial methanotropy) and changes in termite species should result in greater methane/carbon dioxide ratios. Greater organic residue formation is predicted to occur when carbon loss is via termites. Q3. How do mechanisms of wood turnover scale up to affect ecosystem-level carbon fluxes under environmental change? To date, coarse wood debris is poorly parameterized in Earth system models (e.g., coarse wood debris is assumed to decay only via physical fragmentation). Field data from Q1 and Q2 will be used to drive new predictive models of wood turnover and gas emission under environmental change. To test Q1 and determine relative wood-associated microbe and termite decay rates in response to precipitation variation, blocks of pine known to attract termites will be placed at six sites. Blocks will be enclosed in fine-mesh with or without holes to limit termite access. Blocks will be harvested at the end of wet and dry seasons for four years. To determine the influence of wood construction on decay, replicate logs of ten species/site will be placed at rainforest and savannah sites. Logs will be harvested at the end of wet and dry seasons. For logs/blocks, initial and final mass, density and chemistry will be measured. To test Q2, wood subsamples and termites in wood will be collected to determine termite community, microbial community and decay gene composition, and organic residue formation. Carbon dioxide and methane will be measured for harvested logs/blocks. As some termites live in mound nests, experimental mounds will be established and carbon dioxide and methane fluxes will be measured in mounds in a one-year experiment. To test Q3, field data will be incorporated into woodCLM, an ecosystem model derived from the Community Land Model. Results from the modified and original models will be compared. Using woodCLM, wood dynamics and gas emissions will be simulated under future environmental scenarios at the sites. The project will include training at the graduate student and postdoctoral levels, and is part of an international collaborative effort with scientists in England funded by the United Kingdom's Natural Environment Research Council (NERC).

碳的最大生物储层之一是林木的木头。一旦树木死亡，含木材的碳就会被诸如微生物和昆虫等生物消耗。这种碳可以发射到大气中，例如二氧化碳或甲烷气体。此外，只有一些微生物可以分解木质素，这是木材的关键构建块。当他们无法这样做时，剩下的木质素就会锁定在土壤中。热带地区在树木中拥有巨大的碳储存，但对碳的最终结果知之甚少。微生物和白蚁都消耗热带木材，但是这项工作会改变碳的释放速度和形式。通常，微生物需要大量的水分才能在木头上繁衍生息，但是白蚁可能需要更少的水分，因为它们可以藏在巢穴中并储存水，如果它变得太干。科学家一直在试图在环境变化下对全球碳循环进行建模，但是在他们的研究中，他们尚未将微生物和昆虫造成的木材腐烂。这项研究的研究人员预测，这些生物会对全球碳循环产生巨大影响。实验现场工作将在澳大利亚昆士兰州，从湿雨林到干燥的稀树草原，遍及降雨。在这些不同的地点，研究人员将比较白蚁与微生物在潮湿和干燥季节中释放什么气体的速度和什么气体。该结果将被纳入计算机模型，以确定白蚁和微生物如何影响区域与全球尺度的碳循环。这些信息将被馈回科学界，以更好地预测全球碳周期。该项目是美国，英国和澳大利亚科学家之间的国际合作，并在某种程度上受到国际科学与工程办公室的支持。此外，研讨会将与林业利益相关者一起将项目科学家汇集在一起​​，以制定潜在的策略，以防止木材中的碳腐烂，并减少自然碳排放。该项目还将支持初级科学家的教育和培训。该项目将解决三个问题：Q1。什么控制粗木碎屑碳更换的速率？周转率将通过测量白蚁和微生物活动来确定，这些白蚁和微生物活动取决于气候和木材的建设。潮湿的条件应增加营业额，但是由于其节水策略，白蚁应在干燥条件下相对较高的营业额增加。密集，高度木质的木材应更慢。 Q2。什么控制了从粗木碎片中解放的碳命运？碳命运（二氧化碳，甲烷，土壤有机残留物）将取决于木材腐烂的阶段以及白蚁和微生物群落的组成。后来的衰减阶段，甲烷古细菌的丰度或活性增加（或细菌甲苯甲酸的降低）以及白蚁物种的变化应导致甲烷/二氧​​化碳比率更高。预计当碳流失通过白蚁时会发生更大的有机残留形成。 Q3。在环境变化下，木质离职机制的规模如何影响生态系统级的碳通量？迄今为止，在地球系统模型中，粗木碎片的参数较差（例如，假定粗木碎屑仅通过物理碎片腐烂）。来自Q1和Q2的现场数据将用于驱动环境变化下的木材更新和气体排放的新预测模型。为了测试Q1并确定相对木材相关的微生物和白蚁衰减速率，响应降水变化，将在六个地点放置已知吸引白蚁的松树块。块将以有或没有孔的孔封闭，以限制白蚁访问。在湿季节结束时将收获四年的块。为了确定木材结构对腐烂的影响，将在雨林和萨凡纳站点放置十种物种/现场的重复日志。湿季节结束时将收获原木。对于对数/块，将测量初始质量和最终质量，密度和化学。为了测试第二季度，将收集木材的木制子样本和白蚁，以确定白蚁群落，微生物群落和衰减基因组成以及有机残留的形成。将测量二氧化碳和甲烷的收获对数/块。由于某些白蚁生活在土墩巢中，将建立实验丘，并在一年的实验中在土丘中测量二氧化碳和甲烷通量。为了测试第三季度，现场数据将纳入WoodClm，这是一种来自社区土地模型的生态系统模型。将比较修改后的模型和原始模型的结果。使用WoodClm，将在未来的环境场景下模拟木材动力学和气体排放。 该项目将包括在研究生和博士后一级的培训，并且是英国自然环境研究委员会（NERC）资助的英格兰科学家的国际合作努力的一部分。

项目成果

Coevolutionary legacies for plant decomposition

• DOI: 10.1016/j.tree.2022.07.008
• 发表时间: 2022-12-20
• 期刊: TRENDS IN ECOLOGY & EVOLUTION
• 影响因子: 16.8
• 作者: Cornelissen, J. Hans C.;Cornwell, William K.;Zanne, Amy E.
• 通讯作者: Zanne, Amy E.

Termite sensitivity to temperature affects global wood decay rates

• DOI: 10.1126/science.abo3856
• 发表时间: 2022-09-23
• 期刊: SCIENCE
• 影响因子: 56.9
• 作者: Zanne, Amy E.;Flores-Moreno, Habacuc;Zalamea, Paul-Camilo
• 通讯作者: Zalamea, Paul-Camilo

Wood traits explain microbial but not termite‐driven decay in Australian tropical rainforest and savanna

• DOI: 10.1111/1365-2745.14090
• 发表时间: 2023-03
• 期刊: Journal of Ecology
• 影响因子: 5.5
• 作者: S. Law;Habacuc Flores‐Moreno;A. Cheesman;R. Clement;M. Rosenfield;Abbey R. Yatsko;L. Cernusak;J. Dalling;T. Canam;Isra Abo Iqsaysa;Elizabeth S. Duan;S. Allison;P. Eggleton;A. Zanne