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B9) Forest fungi

Effects of forest structures on fungi

Michael Scherer-Lorenzen
Doctoral researcher: Max Wieners (since 2020)

University of Freiburg, Faculty of Biology, Institute of Biology II, Department of Geobotany


Fungi are of ecological importance in forest ecosystems. They drive multiple ecosystem processes, such as the carbon, nitrogen, and phosphorous cycles, and influence plant, animal, and bacterial community structures via biotic interactions (Treseder 2004; Peay et al. 2008). Moreover, with over 14,000 taxa in Germany alone, fungi are a highly species-rich group of organisms, which have been insufficiently studied to date. At the same time, many species are seriously threatened by human impacts (Dämmrich et al. 2016). The reasons given in the "Red List" include a scarcity of old forest stands and old-growth attributes, large diameter biotope wood in addition to the conversion of natural areas.
In biodiversity research, testing of ecological theories is a central task in order to enable a generalization of results from observational studies and experimental approaches. In this project, three theories will be addressed, namely the habitat heterogeneity hypothesis (MacArthur & MacArthur 1961), the theory of metapopulations (Hanski 1999) and the habitat amount hypothesis (Fahrig 2013).


Research questions and hypotheses

The effect of retention forestry on fungi has scarcely been investigated to date and it remains unclear to what extent the results of boreal clear-cutting systems can be transferred to forests in Central Europe. Therefore, the effect of retention measures on the diversity of fungi and the interaction between the studied groups of organisms will be investigated based on four hypotheses:

  1. According to the habitat heterogeneity hypothesis, wood-inhabiting species clearly benefit from an increase in structural diversity on the study sites.
  2. The fragmentation of habitats does not impair the genetic diversity of wind-dispersed fungi, other than predicted by the theory of metapopulations.
  3. Species richness in a fragmented landscape can be well explained by the habitat-quantity hypothesis, since fungi are mostly habitat- and not dispersal-limited.
  4. Due to biotic interactions, there are clear relationships between the diversity of fungi and the diversity of other groups of organisms at the study sites.


Approach, methods and linkages

To record fungal diversity, all macrofungi in the study areas will be documented over tree surveys. For this purpose, two circular subplots with an area of 280 m² each are determined per plot. Fungal species are recorded on the basis of fruiting bodies. Since the focus of this study is on wood-inhabiting species, additional characteristics of the dead wood objects such as size, moss and bark cover, soil contact and degree of decomposition are also documented. To examine the genetic diversity of wind-dispersed fungi sequence polymorphisms of a common and a rare species will be analyzed. Finally, the data collected during this project will be combined with ConFoBi's existing diversity data to investigate relationships between the fungal diversity and the diversity of other groups of organisms.



Dämmrich F, Lotz-Winter H, Schmidt M, Pätzold W, Otto P, Schmitt J A, ... & Wöldecke K (2016) Rote Liste der Großpilze und vorläufige Gesamtartenliste der Ständer- und Schlauchpilze (Basidiomycota und Ascomycota) Deutschlands mit Ausnahme der Flechten und der phytoparasitischen Kleinpilze. In: Matzke-Hajek G, Ludwig G & Hofbauer N (Red.): Rote Liste gefährdeter Tiere, Pflanzen und Pilze Deutschlands. Bd. 8: Pilze (Teil 1) – Großpilze. Naturschutz und Biologische Vielfalt 70(8):31-433.

Fahrig, L. (2013). Rethinking patch size and isolation effects: the habitat amount hypothesis. Journal of Biogeography, 40(9), 1649-1663.

Hanski, I. (1999). Metapopulation ecology. Oxford University Press.

MacArthur, R. H., & MacArthur, J. W. (1961). On bird species diversity. Ecology, 42(3), 594-598.

Peay, K. G., Kennedy, P. G., & Bruns, T. D. (2008). Fungal community ecology: a hybrid beast with a molecular master. Bioscience, 58(9), 799-810.

Treseder, K. K. (2004). A meta-analysis of mycorrhizal responses to nitrogen, phosphorus, and atmospheric CO2 in field studies. New Phytologist, 164(2), 347-355.