Fire is an important ecological and evolutionary force that has shaped the world’s terrestrial ecosystems for millennia, strongly influencing ecosystem distribution and biodiversity patterns in fire-prone landscapes. In large parts of the world, wildfires occur regularly and can have severe environmental consequences: they lead to biomass combustion, trigger changes in soil and nutrient cycling and influence vegetation productivity and dynamics. Fire frequency and extent are expected to increase in the future, as climate change leads to warmer and drier site conditions. Too frequent fires may have severe negative impacts on biodiversity and ecosystem functioning, as some species suffer from fire, when the frequency of disturbance limits recovery.
In our study region, the Amur province in the Russian Far East, fires occur frequently and are characterised by high intensity and large extent. The Amur region comprises huge riverine wetland complexes that are a hotspot of threatened animal diversity. Until now, there are few studies from temperate floodplains, and rarely more than one taxonomic group has been considered in such studies. Therefore, empirical data regarding the responses of different taxa and plant functional groups to fire are needed to inform efficient conservation and habitat management.
We compared species richness and abundance of plants and birds in burnt and unburnt areas in the Amur floodplain/Russian Far East in the year of fire and 1 year after. Additionally, we analysed vegetation and plant growth patterns as well as soil temperature and nutrient concentrations on recently burnt and unburnt control plots and investigated vegetation recovery in relation to time since fire over a period of 18 years. In our studies, we found that:
- The fire effects on biodiversity are taxon- and species-specific. While plant species richness was higher in burnt compared to unburnt plots in the year of the fire, bird species richness and abundance were lower on burnt compared to unburnt plots in the year of the fire. Designing fire “refuges”, i.e., areas that do not burn annually, might locally be necessary to maintain high species richness. Heim et al. 2019 [doi:10.1007/s10531-019-01746-3]
- Over a period of 18 years, high fire frequency led to an increase in herb cover and a decrease in grass cover. Fire management strategies in temperate wetlands should therefore consider fire frequency as a key driving force of vegetation structure, with carry-over effects on higher trophic levels.
- Litter was found to act as a key determinant in the net of direct and indirect fire effects, by influencing early plant growth patterns of herbs and grasses. Furthermore, litter removal through fire significantly increased plant species diversity and soil temperature but decreased N and P concentrations in aboveground biomass. With increasing fire frequency in the course of global change, significant structural and compositional changes in herbaceous wetland vegetation must be anticipated and the studied ecosystem may shift to reinforced N-limitation. Heim et al. 2021 [doi: 10.1016/j.scitotenv.2020.142659]
- Dr. Ramona Heim
- Dr. Wieland Heim, Department of Biology, University of Turku
- Prof. Dr. Dr. h.c. Norbert Hölzel, Institute of Landscape Ecology, University of Münster
- Prof. Dr. Anna Bucharova, Department of Biology, Conservation Biology Group, University of Marburg
- Dr. Galina Darman, Amur Branch of the Botanical Garden-Institute of the Far Eastern Branch of the Russian Academy of Sciences
- PD Dr. Thilo Heinken, Institute of Biochemistry and Biology, University of Potsdam, Germany
- Prof. Dr. Johannes Kamp, Department of Conservation Biology, University of Göttingen, Germany
- Dr. Sergei Smirenski, Muraviovka Park for Sustainable Land Use, Blagoveshchensk, Russia