The legacy of climate change effects: previous drought increases short-term litter decomposition rates in a temperate mixed grass- and shrubland
Fungi play a central role in litter decomposition, a key process controlling the terrestrial carbon cycle and nutrient availability for plants and microorganisms. Climate change and elevated CO2 affect soil fungi, but the relative importance of the global change variables for litter decomposition is still uncertain. The main objective was therefore to assess the short-term litter decomposition and associated fungal community in a global change manipulated temperate heath ecosystem.
The heath had been exposed to 6 years of warming, elevated atmospheric CO2 and an extended pre-summer drought. Litterbags with litter from heather (Calluna vulgaris) and wavy-hair grass (Deschampsia flexuosa) were incubated in the litter layer for 6 months, where after we analyzed the litter-associated fungal community, litter loss, CO2 respiration, and total content of carbon, nitrogen and phosphorus.
Elevated temperature tended to increase litter decomposition rates, whereas elevated CO2 had no effect on the process. The pre-summer drought treatment had a positive impact on litter decomposition, CO2 respiration and fungal abundance in the litterbags, although we observed no major changes in fungal community composition.
The drought treatment during pre-summer had a legacy effect on litter decomposition as decomposition rates were positively affected later in the year. The community structure of litter-decomposing fungi was not affected by the drought treatment. Hence, the legacy effect was not mediated by a change in the fungal community structure.
KeywordsDrought Elevated atmospheric CO2 Increased temperature Fungal community composition Litter degradation Litter mass loss
This study was carried out within the CLIMAITE project, financially supported by the Villum Kann Rasmussen Foundation. We thank Karin Vestberg, Esben V. Nielsen and Anette Hørdum Løth for excellent technical assistance.
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