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

丛枝菌根真菌是热带地区最主要的真菌，在营养贫乏的环境中为包括几乎所有树种在内的绝大多数植物提供矿物质至关重要。因此，对于了解热带生态系统的生物学和生态学，并为全球变化预期下的监测和保护工作提供指导，了解互惠植物-真菌协会是必不可少的。与对鸟类、哺乳动物、土壤节肢动物或水生动物的调查不同，热带地区对丛枝菌根真菌群落的研究很少，从高海拔的厄瓜多尔人PáRamos那里也一无所知。普遍低估分枝杆菌在生态学研究中的重要性和缺乏监测系统的主要原因是对生物采取技术上的困难方法。近年来，分子方法越来越多地被应用于丛枝菌根真菌(AMF)的鉴定，因为即使有详细的描述，形态特征也是不够的。同时，巢式PCR、克隆和Sanger测序是鉴定真菌的成熟方法，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-组合都是显著嵌套的。根据网络模拟，显著的嵌套性，即观察到很少相连的物种优先与高度相连的物种的子集相连，表明真菌和植物的丰富度是通过互惠互利的相互作用而促进的。因此，AMF不仅改善了单个植物的营养，而且还将当地稀有植物物种和真菌整合在一个共同的网络中并加以保护。因此，监测厄瓜多尔安第斯山脉沿大海拔梯度的不同地块中AMF群落的变化，将提供可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，可以对厄瓜多尔最常见的被大火烧毁的地点进行类似的分析。需要评估AMF对场地高程和火灾的敏感性。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换，以评估真菌对气候变化或火灾影响的适应性或敏感度，从而对植物的建立和生长产生影响。因此，为了安装AMF监测系统，有必要与厄瓜多尔合作伙伴一起进行进一步调查，包括低海拔和高海拔，以评估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.