Understanding interactions between deadwood decay, fungal communities and saproxylic insects based on novel field experiments

Deadwood is an important and large carbon pool in unmanaged forests and will become more important in managed forests, as changes in forest management and/or more frequent disturbances will likely lead to higher deadwood amount in Central European forests. Future deadwood dynamics can be currently not accurately assessed due to lack of a conceptual understanding and data on deadwood carbon stocks, carbon fluxes, importance of fungi for deadwood decay and the habitat value of deadwood. In an upcoming 3-year project funded by the Austrian Science Fund, abbreviated with DD FOR, the project team will introduce a conceptual understanding of deadwood dynamics during its observable lifetime from deadwood creation to fragmentation and incorporation into the soil. DD FOR will utilize field experiments of deadwood decay spanning Central European temperature and precipitation gradients (~3-8 °C average annual temperature, ~700-1700 mm annual precipitation sum). The field experiments will focus on important tree species in Central Europe (e.g. Picea abies, Pinus sylvestris, Fagus sylvatica, Quercus sp.). For selected deadwood pieces we will conduct monitoring of saproxylic insects using suitable traps and quantify the fungal communities using wood samples, fruiting body inventories and state-of-the-art analytical methods, including meta bar-coding. This will establish decay rate benchmarks for fungal species, depending on climate and their host species.

We hypothesis that temperature is the main driver of deadwood decay and that moisture modulates decay with implications on fungal communities and insect habitat quality. Presence and diversity of saproxylic insects may explain variation in fungal diversity, not explained by site or stand conditions. Pilot studies suggest that (1) novel techniques are needed to quantify properties of well-decayed deadwood, including drill-resistance tools and moisture sensors, (2) deadwood position and deadwood treatment affects deadwood decay and (3) permanent plots are valuable assets and can serve as field labs for understanding deadwood dynamics. Results of DD FOR will assist deadwood-focused forest management and better consideration of deadwood in greenhouse gas reportings.

Literature
Neumann, Mathias, Sebastian Echeverria, and Hubert Hasenauer. 2023. “A Simple Concept for Estimating Deadwood Carbon in Forests.” Carbon Management 14(1):1–12. doi: 10.1080/17583004.2023.2197762.

Neumann, Mathias, Clemens Spörk, and Hubert Hasenauer. 2023. “Changes in Live and Deadwood Pools in Spruce-Fir-Beech Forests after Six Decades of Converting Age Class Management to Single-Tree Selection.” Trees, Forests and People 12(January):100382. doi: 10.1016/j.tfp.2023.100382.

Kušar, Gal, and Mathias Neumann. 2024. “Patterns of Deadwood Volume and Dynamics in Slovenian Forests.” Acta Silvae et Ligni 133:1–12. doi: 10.20315/ASetL.133.1.