Diversity of AM fungi in mountain forests of South Ecuador

People

Ingeborg Haug, Jutta Bloschies, Sabrina Setaro, Juan Pablo Súarez

Funding

Deutsche Forschungsgemeinschaft (DFG)

Duration

June 2014 - November 2018

In a nutshell

The final goal of the research is to define a scientifically firmly based technical system for rapid monitoring of arbuscular mycorrhizal fungi (AMF). No such monitoring system exists so far. The monitoring in our case shall especially address sensitivity of AMF against climate warming and disturbance in the tropical Andes. Local Ecuadorian collaborators are included in the development of the monitoring system in order to facilitate transfer of the system for long-term monitoring by the local people. Mycorrhizal fungi are most crucial for terrestrial ecosystem stability as fostering plant growth, health and diversity as well as soil aggregation.

Project description

Work package 1: Sampling and identification of arbuscular mycorrhizal fungi to complete the AMF data set

In order to complete the current data set on AMF obtained from an insufficient longitudinal gradient, further root sampling will be carried out in the mountain rain forest at RBSF (2000 m), and sampling will be expanded to the premontane forest in Bombuscaro (bordering San Francisco river at 1000 m), the high elevation Cajanuma (2800 - 3000 m) and Cajas Páramo (3200 – 4000 m). The large altitudinal gradient is serving as kind of “climate change experiment”. The mycorrhization will be checked with light microscopy and arbuscular mycorrhizal fungi will be identified with molecular methods.

Work package 2: Analysis of network structure for evaluation of degree of stability (nestedness) and compartmentalisation (modularity)

Networks as defined here are a set of nodes (species) connected through links (interactions). Mutualistic networks involving arbuscular mycorrhizas are two-node networks since there are two well-defined types of nodes, the arbuscular mycorrhizal fungi belonging to the Glomeromycota and the plant species, and mutualistic interactions occur between but not within these node types. We will test for potential nestedness of plant-fungal networks at our study sites and in the whole network. We will test for stability of the overall network by simulation loss of species. By stepwise eliminating highly linked or rarely linked species and recalculation NODF as measure of stability we will obtain insight on importance of diversity and of frequent or rare species on stability.

Work package 3: Analysis of network modularity in respect to altitudinal gradient and habitat destruction

We will test for modularity in the network structure. Levels of specialisation between plants and AMF will be assessed.

Work package 4: Define target AMF for the monitoring system

The network matrix will be used to calculate the degree of links of each AMF OTU by the marginal totals in the overall network and the site specific networks. AMF-OTU frequencies and occurrences will be evaluated taking into account also the results from workpackage 2 to select the keystone AMF, indicative of a stable network, for future long-term monitoring at different altitudes and land use gradients.

Work package 5: Define target plant species and plots at the different sites for monitoring of the target AMF species.

Similar to definition of target AMF, plants with high linkage degree will be visible from the marginal totals of the network matrices. It needs to be checked if the defined keystone AMF are frequently linked to the frequently occurring and easily accessible plant species for root excavation. Three to five plant species will be selected at each plot for future monitoring.