(TU Dresden – IHI Zittau)
(Centre For Environmental Research -UFZ, Halle)
(Bavarian Forest National Park, Grafenau)
(Julius Kühn-Institute, Braunschweig)
Compared to predecessor projects FunWood I-II, which conceptually focused on the impact of different forest management regimes on microbial diversity in existing coarse woody debris (CWD) already in the process of being decomposed, we now focus on a more standardized experimental system. The BELongDead experiment was conceived in 2008 under the direction of Prof. E. D. Schulze (MPI Biogeochemistry Jena) with the intention to monitor the impact of habitats on the dead wood decomposition processes and to observe colonization patterns of various saproxylic organisms over long time. Its central questions are I) how does the surrounding ecosystem influence wood decomposition, II) how does succession of the substrates proceed and III) how do microorganisms mediate wood decay and subsequently impact ecosystem processes like element turnover and storage. This enables us now to investigate the direct influence of different forest management regimes on a sizeable set of 12 (+1 less frequent) different dead wood tree species each homogenous in their initial wood properties (decay stage, volume, water content) and evenly distributed in replicates across plots, landscapes and management types.
We use state of the art molecular methods in combination with classic approaches I) to identify and quantify wood decomposition changes under different forest managements, II) to reveal patterns of dispersal and succession of fungi and monitor them over longer decomposition periods, III) to analyse metabolic fungal activity on transcript- and enzyme- levels and relate them to observed processes, IV) to analyse resulting changes in wood chemistry, V) to analyse the effects of N-fixing bacteria on fungal wood decomposition, and VI) finally identify key species driving the observed changes under these different forest management practices.
Our central hypotheses are:
1. Forest management intensity decreases the species pool of wood-inhabiting fungi on the landscape and stand scale.
2. Forest management intensity acts as a habitat filter that selects on species with certain traits (e.g. generalists) leading to a functional clustering.
3. Forest management relaxes competitive interactions among wood-inhabiting fungi leading to overall increased decomposition rates.
4. Decomposition processes are well predictable by analyzing fungal sporocarp diversity along with molecular species, phylogenetic and functional diversity.
5. There is a constant N-fixation by bacteria in dead wood, and particular bacterial species co-occur with particular fungi. This will be addressed by stable isotope probing and co-occurence network analyses to find N-fixating key players.
6. Among fungal secretory peroxidases (ligninolytic class II peroxidases, dye-decolorizing peroxidase, heme-thiolate peroxidases) expressed in wood, manganese peroxidase (member of class II) is the most diverse, most abudant and thus most important peroxidase in wood-lignin decomposition.
7. Peroxidase transcript diversity generally increases with white-rot basidiomycete species diversity, however, transcript abundance varies according to fungal occupation (i.e. aggressive decayers dominate patches and express peroxidases more abundantly).
We intend to apply a variety of molecular methods on DNA and RNA level, encompassing Next Generation Sequencing (NGS). We further aim to prove and quantify nitrogen fixation in a customized experimental platform, combining NGS metagenomics with real-time PCR and bioanalytics (acetylene reduction test, stable isotope probing SIP and Isotopic Mass Spectrometer Analyses IRMS).
Besides a dense sampling of sporocarps, we also intend to measure the variation in airborne fungal spore communities among the forest management treatments by setting up cyclone samplers in order to compare species presence in air with those already and actually established on the local dead wood sites.
Previous project contribution of Dr. Björn Hoppe: Funwood I-II