Fungal Ecology by Tessa Camenzind

Contact:

Freie Universität Berlin, Germany

Institute of Biology - Plant Ecology

TessaC [at] zedat.fu-berlin.de

@t_camenzind

News section



General research interests

Currently I am working as a postdoc in the Plant Ecology group at Freie Universität Berlin. My work as a soil ecologist focuses on the role of fungi and microbes in soil nutrient cycling and carbon dynamics, with a strong emphasis on fungal nutrient use efficiency and carbon demands.

Already my PhD thesis “Responses of arbuscular mycorrhizal fungi to nutrient additions in a tropical montane forest” not only got me hooked on working in diverse tropical forests, expanding my knowledge to different ecosystems, but also on thinking more deeply about the interplay of microbes with elements in soil. For years I studied the fascinating symbiosis of arbuscular mycorrhizal fungal communities with plants in respect to soil nutrient status in pristine tropical forests, Dark Earth soils in tropical Africa, as well as tropical but also temperate pasture and grassland systems. Based on the gained knowledge my research interests broadened towards nutrient limitations of other microbial groups in soil, especially saprobic fungi, and consequent implications for ecosystem processes.

My current project focuses on nutrient demands and stoichiometric patterns in saprobic fungi, aiming to investigate stoichiometry as an ecological trait for soil fungi.

Research

We designed fungal growth media suitable to test for growth limitations by individual elements. Responses to N and P limitations tested in many fungal isolates covering three fungal phyla showed very distinct shifts in trait expressions, indicating a switch from explorative growth under low nutrient conditions to exploitative growth with dense and highly active mycelia in high nutrient patches. A parallel analysis of fungal stoichiometric patterns indicated a non-homeostatic shift in C:N:P ratios, contradicting common assumptions of microbial homeostasis. Mechanisms explaining this stoichiometric flexibility also relate to the mycelial lifestyle, which enables nutrient translocation and recycling within the mycelium.

Further projects aim to translate these physiological findings under more controlled conditions towards observations in soil, in order to understand the relevance of stoichiometric fungal shifts in soil, predict carbon versus nutrient limited growth and activity in soil and improve current models of microbial mediated carbon and nutrient cycling dynamics.

©Tessa Camenzind

The simple agricultural concept of Liebig´s law of the minimum predicts that only the most limiting element in soil restricts plant growth. In natural diverse ecosystems, productivity is indeed often limited by nitrogen (N) and phosphorus (P) availability, though patterns were revealed to be far more complex - with co-limitations occurring, overlooked elements playing important roles and functional or phylogenetic groups being affected differentially by various elements. In recent years a growing number of interesting studies based on nutrient manipulation experiments revealed new insights on this topic, though often with a focus on plants and aboveground processes. Since plant growth and primary productivity depend on nutrient recycling in soil, nutrient demands of soil microbes mediating those processes and above- belowground interactions are of equal relevance. Summarizing available findings on soil microbial responses to nutrient manipulations gave valuable insights on nutrient limitations of soil microbes in general (Camenzind et al. 2018). Additional case studies combining large- and small-scale nutrient manipulation approaches allow for a more detailed analysis of microbial element demands, especially of saprobic fungi (Camenzind et al. 2019). Potential demands for elements like carbon, nitrogen, phosphorus, calcium, potassium or sodium are quantified in controlled media, and actual limitations tested in parallel in field experiments (see Publications).

©Tessa Camenzind

The ubiquitous group of arbuscular mycorrhizal fungi (AMF) is not only relevant for plant and microbial community dynamics and soil processes, but especially enhances plant nutrient uptake. Thus, nutrient limitations and alteration in element inputs by anthropogenic activities affect this important plant-fungus association. We investigated in multiple study systems the responses of AMF to nutrient manipulations, analyzing extra- and intraradical AMF abundance as well as AMF community structure. In most systems nitrogen (N) and phosphorus (P) availablity strongly control the AMF association and especially species composition (see Publications), though unifying patterns and functional implications are difficult to derive from those complex results. Next steps are to combine observational data with functional experiments, to understand implications of shifts in AMF abundance and communities for ecosystem processes, and combine findings from different systems to detect common patterns enabling us to predict future responses to environmental change.

For details on my research projects please refer to my Publications

Traveling the world as an ecologist

I aimed to be biologist for many reasons, but one of them was definitely to have a job enabling me to explore as many places on this planet as possible. Though my Curriculum Vitae may not reflect this passion adequately, since I was not able for personal reasons to change my location for longer periods, I still used every opportunity to make short journeys for field trips, scientific exchange with counterparts and colleagues and attend international conferences. These interactions, but also the work within the inspiring large international research group of Matthias Rillig and for a long time also as part of the Ecuadorian research unit funded by the Deutsche Forschungsgemeinschaft, enabled me to establish several cooperations around the world which were crucial for the realization of most research projects.