Maintenance of biodiversity through mutualistic networks between arbuscular mycorrhizal fungi and plants: robustness against human disturbance and climate change

丛枝菌根真菌（Glomeromycota）是热带地区最重要的分枝菌，在营养贫乏的环境中为绝大多数植物（包括几乎所有树种）提供矿物质。因此，了解植物-真菌的共生关系对于理解热带生态系统的生物学和生态学是必不可少的，并为全球变化预期下的监测和保护工作提供指导。与对鸟类、哺乳动物、土壤节肢动物或水生动物的调查相比，丛枝菌根真菌群落在热带地区的研究很少，对高海拔的厄瓜多尔Páramos也一无所知。人们普遍低估了mycobionts在生态学研究中的重要性，并且缺乏监测系统，其主要原因是技术上难以接近这些生物。近年来，由于对丛枝菌根真菌（AMF）的形态特征描述不够详细，分子方法越来越多地应用于鉴定丛枝菌根真菌（AMF）。同时，巢式PCR、克隆和Sanger测序是真菌鉴定的成熟方法，申请人基于这些方法为安第斯热带山林提供了一套完整的AMF序列数据集。生态网络理论的应用表明，所有研究的amf组合都具有显著的嵌套性。根据网络模拟，显著的巢性，即很少联系的物种优先与高度联系的物种的子集联系，表明真菌和植物的丰富度是由互惠相互作用促进的。因此，AMF不仅改善了单个植物的营养，而且在一个共同的网络中整合并保存了当地稀有的植物物种和真菌。因此，监测厄瓜多尔安第斯山脉地区沿着大海拔梯度的样地之间AMF群落的变化将提供可以在功能层面上解释气候变化的数据。与未受干扰的地点相比，可以对被火烧毁的地点（在厄瓜多尔最常见）进行类似的分析。AMF对场地高程和火灾的敏感性需要评估。有必要了解AMF是否可以在与海拔和干扰相关的模块之间转移，以评估分枝菌体对气候变化或火灾影响的适应性或敏感性，从而影响植物的建立和生长。因此，为了安装一个AMF监测系统，有必要与厄瓜多尔合作伙伴一起进一步调查，包括低海拔和高海拔，以估计AMF作为气候变化和火灾破坏指示生物的敏感性。

Arbuscular mycorrhizal fungi (Glomeromycota) are the most prominent mycobionts in the tropics and crucial for providing minerals to the vast majority of plants including nearly all tree species in the nutrient poor environments. Thus, knowledge of the mutualistic plant-fungus associations is indispensable for understanding the biology and ecology of tropical ecosystems and give guidelines for monitoring and conservation efforts under global change expectations. In contrast to surveys on birds, mammals, soil arthropods or aquatic animals, arbuscular mycorrhizal fungal communities have been rarely studied in the tropics, and nothing is known from the high elevation Ecuadorian Páramos. The main reason for the widespread underestimation of the importance of mycobionts in ecological studies and the lack of a monitoring system is the technically difficult approach to the organisms. During recent years molecular methods were increasingly applied to identify the arbuscular mycorrhizal fungi (AMF) because morphological features proved as insufficient even with detailed description. Meanwhile, nested PCR, cloning and Sanger sequencing are well-established methods for identification of the fungi and a comprehensive data set of AMF sequences has been provided for the Andean tropical mountain forest based on these methods by the applicant. Application of ecological network theory revealed that all studied AMF-assemblages were significantly nested. According to network simulations, significant nestedness, the observation that rarely linked species preferentially link to subsets of highly linked species, indicates that richness of fungi and plants are promoted by the mutualistic interaction. AMF, therefore, not only improve nutrition of individual plants but also integrate and thus preserve locally rare plant species and fungi in a common network. Thus, monitoring the changes of AMF communities among plots along a large elevation gradient as present in the Ecuadorian Andeans will supply data that can be interpreted on a functional level with respect to climate changes. Similar analyses can be carried out for fire-destroyed sites, most common in Ecuador, in comparison to undisturbed sites. The sensitivity of AMF to site elevation and fire needs to be assessed. It is necessary to know if AMF can shift among the modules related to elevation and disturbance to evaluate in as much the mycobionts are resilient or sensitive to climate change or fire affection with consequences for plant establishment and growth. Thus, to install a monitoring system for AMF, further investigation together with the Ecuadorian partners including low and high elevation is necessary to estimate the sensitivity of AMF as indicator organisms for climate change and fire destructions.