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).

最大的碳生物库之一位于森林树木的木材中。一旦树木死亡，木材中的碳就会被微生物和昆虫等生物体消耗。这种碳可以二氧化碳或甲烷气体的形式排放到大气中。此外，只有一些微生物可以分解木质素，木质素是木材的关键组成部分。当他们无法做到这一点时，剩余的木质素就会被锁在土壤中。热带地区的树木中储存了大量的碳，但人们对这些碳的最终去向知之甚少。微生物和白蚁都会消耗热带木材，但哪一种完成这项工作会改变碳释放的速度和形式。通常，微生物需要大量的水分才能在木材上繁衍生息，但白蚁可能需要较少的水分，因为如果天气太干燥，它们可以隐藏在巢穴中并储存水。科学家们一直在尝试模拟环境变化下的全球碳循环，但他们尚未将微生物和昆虫引起的木材腐烂纳入研究中。这项研究的研究人员预测这些生物体对全球碳循环具有巨大影响。实验现场工作将跨越澳大利亚昆士兰州降雨量不同的生态系统，从潮湿的雨林到干燥的稀树草原。在这些不同的地点，研究人员将比较白蚁与微生物消耗木材的速度以及在雨季和旱季释放的气体。研究结果将被纳入计算机模型中，以确定白蚁和微生物如何影响区域到全球范围内的碳循环。这些信息将反馈给科学界，以便对全球碳循环做出更好的预测。该项目是美国、英国和澳大利亚科学家之间的国际合作，并得到美国国家科学基金会国际科学与工程办公室的部分支持。此外，研讨会还将汇集项目科学家和林业利益相关者，制定防止木材中碳腐烂和减少自然碳排放的潜在策略。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。什么控制粗木屑碳周转率？周转率将通过测量白蚁和微生物活动来确定，这取决于气候和木结构。潮湿的条件应该会增加周转率，但由于白蚁的节水策略，在干燥的条件下，白蚁的周转率应该相对更高。致密、高度木质化的木材腐烂得更慢。 Q2。是什么控制着从粗木屑中释放出的碳的命运？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。腐烂的后期阶段、产甲烷古菌的丰度或活性增加（或细菌甲烷氧化性降低）以及白蚁物种的变化应导致更大的甲烷/二氧​​化碳比率。当白蚁造成碳损失时，预计会形成更多的有机残留物。 Q3。环境变化下木材周转机制如何扩大影响生态系统水平的碳通量？迄今为止，粗木碎片在地球系统模型中的参数化很差（例如，粗木碎片被假设仅通过物理碎片腐烂）。第一季度和第二季度的现场数据将用于驱动环境变化下木材周转和气体排放的新预测模型。为了测试 Q1 并确定与木材相关的微生物和白蚁随降水变化的相对腐烂率，已知会吸引白蚁的松木块将被放置在六个地点。块将被封闭在带孔或不带孔的细网中，以限制白蚁进入。荒料将在四年的雨季和旱季结束时收获。为了确定木结构对腐烂的影响，将在雨林和稀树草原地点放置十个物种/地点的复制原木。原木将在雨季和旱季结束时收获。对于原木/块，将测量初始和最终质量、密度和化学成分。为了测试 Q2，将收集木材子样本和木材中的白蚁，以确定白蚁群落、微生物群落和腐烂基因组成以及有机残留物形成。将测量收获的原木/木块的二氧化碳和甲烷。由于一些白蚁生活在土丘巢中，因此将建立实验土丘，并在为期一年的实验中测量土丘中的二氧化碳和甲烷通量。为了测试第三季度，现场数据将被纳入 woodCLM，这是一个源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，将在现场的未来环境情景下模拟木材动态和气体排放。 该项目将包括研究生和博士后级别的培训，是英国自然环境研究委员会（NERC）资助的与英国科学家国际合作项目的一部分。

项目成果

Coevolutionary legacies for plant decomposition

植物分解的共同进化遗产

• DOI: 10.1016/j.tree.2022.07.008
• 发表时间: 2023-01
• 期刊: Trends in Ecology & Evolution
• 影响因子: 16.8
• 作者: Cornelissen, J. Hans;Cornwell, William K.;Freschet, Grégoire T.;Weedon, James T.;Berg, Matty P.;Zanne, Amy E.
• 通讯作者: Zanne, Amy E.

Termite sensitivity to temperature affects global wood decay rates

白蚁对温度的敏感性影响全球木材腐烂率

• DOI: 10.1126/science.abo3856
• 发表时间: 2022-09
• 期刊: Science
• 影响因子: 56.9
• 作者: Zanne, Amy E.;Flores;Powell, Jeff R.;Cornwell, William K.;Dalling, James W.;Austin, Amy T.;Classen, Aimée T.;Eggleton, Paul;Okada, Kei;Parr, Catherine L.;et al
• 通讯作者: et al

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

木材特征解释了微生物而非白蚁导致的澳大利亚热带雨林和稀树草原的腐烂

• 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: Law, Stephanie;Flores‐Moreno, Habacuc;Cheesman, Alexander W.;Clement, Rebecca;Rosenfield, Marc;Yatsko, Abbey;Cernusak, Lucas A.;Dalling, James W.;Canam, Thomas;Iqsaysa, Isra Abo;et al
• 通讯作者: et al