(TU Dresden – IHI Zittau)
(Centre For Environmental Research -UFZ, Halle)
(Goethe University Frankfurt)
(Julius Kühn-Institute, Braunschweig)
Deadwood is an important source of organic carbon and nutrients in forest ecosystems, which is continuously degraded by macro- and microorganisms, which hereby structure the ecosystems and impact multiple ecosystem functions. Though many contributions on species diversity for single taxonomic groups in relation to various deadwood substrates have been made through the last years, we are still lacking comprehensive understanding how wood-inhabiting species are organized and assemble over time and how they specifically contribute to wood decomposition processes.
Our project is part of the BELongDead (Biodiversity Exploratories Long-term Deadwood) experiment that elucidates the decomposition of deadwood logs of thirteen deciduous and coniferous temperate tree species, standardized by the same starting time point of decomposition. We intend to quantify all relevant underlying molecular and biochemical mechanisms and processes of microbial-mediated wood decomposition in relation to forest management practices and geographical scale.
Particularly, we analyse:
- how species colonize a deadwood object,
- how communities from different taxa interact during succession,
- how the importance of host characteristics and environment change during succession and
- whether the relationship between diversity and decomposition can be better understood by considering multiple taxa.
We use classical sampling methods and state of the art molecular tools to capture as many aspects of diversity und community structure (Fig. 1). This information will be linked to wood chemistry, activity patterns of decomposing enzymes and wood decomposition in general. We collect the following data on two experiments:
- DNA-based diversity of fungi, bacteria, archaea and nematodes
- Diversity of fungal fruit bodies, lichens and mosses (Fig. 2)
- Wood characteristics such as pH value, C/N ratio, lignin content
- Activities of wood-degrading enzymes (e.g. peroxidases, laccases)
After sampling in 2012, 2015 and 2017, our data set is currently extended by a fourth time point in 2020 in order to be able to evaluate the processes of wood decomposition from the initial to the very advanced decomposition phase.
In an additional deadwood experiment covering the two main species within Central European forests (Fagus sylvatica and Picea abies) we will expose gamma sterilized and non-sterilized (harboring natural endophytes) logs next to the existing BELongDead logsand in a well-defined distance to the BELongDead objects (see Fig. 3A). Using our newly developed add-on experiment we aim at addressing two fundamental research questions:
- a comparison between the sets of non-sterilized logs (characterized by the endophyte community) and sterilized (controls) will allow to test and answer the question whether observed and anticipated differences of the fungal diversity between different tree species is caused mainly by the endophyte communities (Fig. 3B, Hypothesis H3a) or alternatively by host tree characteristics (e.g. wood physico-chemical properties, Fig. 3B, Hypothesis H3A).
- We expect that the probability of colonization will depend on the donor pool. If this holds true, we would observe significant differences in colonization patterns between the logs that are exposed directly on the BELongDead plots (more exposed to the local species pool) compared to logs that are exposed in a certain distance (‘away’, more exposed to the regional species pool. If the endophytic community offsets the effect of the donor pool, we will observe a similar community between all logs of the same tree species (Fig. 3C, Hypothesis H3b).