Relating fungal functional diversity to C-cycling in sub- and Maritime Antarctic soils

有机物的分解是陆地生态系统功能的关键过程。这一过程主要是由土壤和植物凋落物中的腐解真菌驱动的。因此，腐食性真菌在陆地生态系统以CO2（一种气候强迫气体）的形式向大气释放碳（C）方面发挥着关键作用。目前，很少有人知道的具体作用，个别真菌物种，即功能多样性，在特定的C组分的降解分和海洋南极。在功能多样性的特征的第一步是确定土壤中的分解真菌与土壤C组分（馏分，颗粒大小和年龄）。建立基线真菌分类和功能多样性和土壤C组分的特点-本提案的中心目标-是了解环境变化对南极生态系统的影响的基础。为什么要选择南极洲的海底和海上？由于有机物分解缓慢和苔原植被的存在，这些地区的土壤具有相对较高的碳储量。例如，南格鲁吉亚和西尼岛的土壤中含有30 - 40%的C。这些土壤的潜在温度响应和它们所含的C组分对于理解也很重要，因为陆地海洋南极一直在迅速变暖，在c。在过去的50-100年里，每十年上升0.2-0.4摄氏度，这是有记录以来最快的变暖速度之一。年轻和老年C馏分在释放二氧化碳到大气中的温度敏感性是有争议的，特别是泥炭地和永久冻土，如那些发生在次和海洋南极。我们将确定协会的特定真菌类群与特定的有机组分在该领域在三个地点在分和海洋南极，并通过年龄和有机地球化学，这些组分的C组分。在实验室中，将确定由“关键”真菌物种矿化的特定C组分，以及对温度升高和冻融循环的反应。该项目的成果将是：（1）更好地了解特定真菌群在碳循环中的作用，（2）将获得未来研究（例如在北极或温带土壤中）真菌菌丝体与碳矿化作用的功能作用的基准，以及（3）将确定温度升高/冻融对碳矿化的影响。

The decomposition of organic matter is a critical process to the functioning of terrestrial ecosystems. This process is largely driven by saprotrophic (decomposer) fungi in soil and plant litter. Saprotrophic fungi therefore have pivotal roles in the release of carbon (C) from terrestrial ecosystems, in the form of CO2 (a climate-forcing gas), to the atmosphere. Currently, little is known of the specific roles of individual fungal species, i.e. functional diversity, in the degradation of particular C components in the sub- and Maritime Antarctic. The first step in characterising functional diversity is to identify the soil C components (fractions, particle sizes and ages) with which decomposer fungi in soil are associated. Establishing baseline fungal taxonomic and functional diversity and characterizing the soil C components - central aims of this proposal - are fundamental to understand the impacts of environmental change on Antarctic ecosystems. Why the sub- and Maritime Antarctic? Soils in these regions have relatively high stocks of C because of the slow decomposition of organic matter and the tundra vegetation present. For example, soils from South Georgia and Signy Island contain 30 to 40% C. The potential temperature responses of these soils and the C fractions they contain are also important to understand because the terrestrial Maritime Antarctic has been warming rapidly, at c. 0.2-0.4 degrees C per decade over the past 50-100 years, one of the fastest rates of warming recorded. The temperature sensitivity of young and older C fractions in releasing CO2 to the atmosphere is much debated, particularly for peatlands and permafrost soils, such as those that occur in the sub- and Maritime Antarctic. We will determine the associations of specific fungal taxa with specific organic fractions in the field at three sites in the sub- and Maritime Antarctic, and characterise by age and organic geochemistry, the C components of these fractions. In the laboratory, the specific C fractions mineralised by 'key' species of fungi will be determined, together with responses to temperature increases and freeze-thaw cycles. The outcomes of the project will be: (1) a better understanding of the roles of particular groups of fungi in the C cycle, (2) a benchmark for future studies (e.g. in arctic or temperate soils) of the functional roles of fungal mycelia in relation to C mineralisation will have been obtained, and (3) the effects of temperature increases / freeze-thaw on C mineralisation will have been determined.