Collaborative Proposal - Quantifying the footprint of a dominant organism: Biogeochemical impacts of leaf cutter ants in a lowland tropical forest ecosystem

合作提案 - 量化优势生物的足迹：低地热带森林生态系统中切叶蚁的生物地球化学影响

• 批准号: 1442568
• 负责人: Thomas Harmon
• 金额: $ 13.77万
• 依托单位: University of California - Merced
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1442568&HistoricalAwards=false
• 关键词: Collaborative; Proposal; Quantifying; footprint; dominant

This project will provide information on the contribution of an ecologically important ant guild to the carbon cycle and will help improve predictions of future carbon dynamics in tropical forests. One of the most conspicuous features of a tropical forest is the abundance of leaf cutter ants. Despite their prominence, little is known about the overall contribution of leaf cutter ants to carbon and nutrient cycles in tropical ecosystems. These tropical and subtropical forested ecosystems cover 17% of the Earth's land mass and store approximately 40% of all carbon and are an important determinant of the global carbon cycle. Leaf cutters are the dominant herbivores in tropical forest ecosystems, bringing 10-50 % of all surrounding vegetation into the nest, fertilizing nest soils, and promoting the release of carbon dioxide and methane into the atmosphere. The network of leafcutter ant trails extend throughout the forest and workers walk single-file, carrying pieces of leaves into their nests, where special fungi break down the plant material and produce hyphae, on which the ants feed. Leaf cutter ant nests are massive in size and during nest construction and maintenance ants mix leaf particles into the soil and alter soil chemistry. Leaf cutter ant activities have the possibility of controlling aspects of ecosystem dynamics, though the degree of their influence has not been quantified. The project will focus on the role of leafcutter ant nests as hotspots of carbon dioxide and methane emissions and the role of nests in altering soil chemistry and creating heterogeneity in carbon (C), nitrogen (N), and phosphorus (P) in the soil across the landscape. The work will be conducted at La Selva Biological Research Station, Costa Rica, which is an epicenter of tropical scientific research, hosting a large number of student groups, researchers from all over the world. The project will characterize C dynamics on leafcutter ant nests and differentiate the sources of carbon dioxide and methane emissions between the activities of ants, fungi, the nest microbial community, and roots and hyphae. The N, and P biogeochemistry of active leafcutter ant nests will be quantified as well as the soil legacy effects after nests are abandoned. The project uses a multi-faceted approach, including coupling continuous measurements of soil carbon dioxide emissions with discrete measures of methane efflux, stable C isotopes of carbon dioxide to determine sources, soil C and N pools and fluxes, estimates of root and fungal biomass, and microbial community and functional indices. Measurements will be performed on ant nests, paired non-nest sites, and along a sequence of nests abandoned at different times in the past to quantify how long the impact of altered biogeochemistry persists in areas occupied by nests. These biogeochemical fluxes will be incorporated into an ecosystem model to estimate C flux at local-to-regional scales. The project will strengthen international collaborations by working with researchers and students from the US, Costa Rica, and New Zealand. In addition to training a postdoctoral researcher and mentoring several REU students, project scientists will conduct an annual workshop to introduce students and researchers to cutting edge field instrumentation and analysis techniques and provide opportunities to use these new approaches at La Selva. La Selva Biological Research Station is an epicenter of tropical scientific research, hosting a large number of student groups, researchers from all over the world, and serving as a center for ecotourism, thus the proposed research will be widely disseminated.

该项目将提供有关生态上重要的蚂蚁公会对碳循环的贡献的信息，并有助于改善对热带森林未来碳动态的预测。 热带森林中最明显的特征之一是叶片的丰度。尽管它们突出，但对叶轮蚂蚁对热带生态系统中碳和养分周期的总体贡献知之甚少。这些热带和亚热带森林的生态系统占地17％的土地质量，并储存了大约40％的所有碳，并且是全球碳循环的重要决定因素。叶刀是热带森林生态系统中的主要食草动物，将所有周围植被的10-50％带入巢中，施肥巢土壤，并促进二氧化碳和甲烷释放到大气中。叶刀径的网络遍及整个森林，工人在单文件中行走，将叶子带入巢中，特殊的真菌分解了植物材料并产生菌丝，蚂蚁在该植物上进食。叶片切割器的巢的大小巨大，巢结构和维护期间，蚂蚁将叶片颗粒混合到土壤中，改变土壤化学。叶片切割器的蚂蚁活动具有控制生态系统动力学方面的可能性，尽管尚未量化其影响的程度。该项目将集中于叶牛肉巢的作用，作为二氧化碳和甲烷排放的热点，以及巢在改变土壤化学的作用并在跨景观中碳（C），氮（N）和磷（P）创造异质性。这项工作将在哥斯达黎加的La Selva生物学研究站进行，该站是热带科学研究的震中，拥有来自世界各地的研究人员的大量学生群体。 该项目将在叶刀巢上表征C动力学，并区分蚂蚁，真菌，巢微生物群落以及根和菌丝的二氧化碳和甲烷排放的来源。活性叶刀巢的N和P生物地球化学将被量化，以及放弃巢穴后的土壤遗产效应。该项目采用了多方面的方法，包括将土壤二氧化碳排放量的连续测量与甲烷外排的离散度量进行连续测量，二氧化碳稳定的C同位素确定源，土壤C和N池和N池和N池和N池，估计根和真实的生物群，以及微生物群体和微生物群体和功能率。测量将在蚂蚁巢，配对的非巢位点以及过去在不同时间遗弃的一系列巢上进行测量，以量化改变生物地球化学的影响在巢穴所占据的区域的影响。这些生物地球化学通量将纳入生态系统模型中，以估计局部到区域尺度的C通量。该项目将通过与美国，哥斯达黎加和新西兰的研究人员和学生合作来加强国际合作。除了培训博士后研究人员并指导几名REU学生外，项目科学家还将举办年度研讨会，向学生和研究人员介绍尖端现场仪器和分析技术，并提供机会在La Selva使用这些新方法。 La Selva生物学研究站是热带科学研究的震中，拥有大量的学生群体，来自世界各地的研究人员，并且是生态旅游中心，因此拟议的研究将被广泛传播。