The anthropogenic increase in CO2 emission and the consequent increased concentrations in the atmosphere will result in increased temperatures on earth, affecting all biota. The temperature sensitivity of soil microbial activity has been a topic of considerable interest and debate, especially soil respiration due to its potential feedback effects on climate change. The extent of temperature adaptation of the soil microbial community is also a topic with divergent results. Recent studies have suggested either adaptation or no response to altered temperature regimes. There is also no consensus in what way temperature affects the balance between fungal and bacterial growth in soil. We aim to attack these problems by measuring bacterial and fungal growth in natural habitats under different temperature regimes. Earlier studies by us showed that respiration rate, bacterial and fungal growth follow the square root relationship with changes in temperature, a model well proven and used within microbiology. Thus, below optimum temperature for growth, a plot of the square root of the growth or activity against temperature) will result in a linear relationship, with Tmin indicated by the intercept with the x-axis (Figure, lower panel, where arrows indicate Tmin, lowest in AI (Antarctic samples) and highest in Swedish samples). This model can thus be used to differentiate between direct temperature effects and community adaptation.
In this project we will determine the effect of increasing temperature on the temperature relationship of bacterial activity in soil, including possible community adaptation. We will also compare the effect of temperature on fungal and bacterial growth adaptation and study if temperature will affect the balance between fungal and bacterial decomposition. Last, we will study how fungi and bacteria are affected by natural, reoccurring perturbations that are supposed to increase in future global change scenarios.
Pietikäinen J., Pettersson M. & Bååth E. (2005) Comparison of temperature effects on soil respiration and bacterial and fungal growth rates. FEMS Microbiology Ecology 52: 49-58.
Rinnan R., Rousk J., Yergeau E., Kowalchuk G.A. & Bååth E. (2009) Temperature adaptation of soil bacterial communities along an Antarctic climate gradient. Global Change Biology 15(11): 2615-2625.
Bárcenas-Moreno G., Gómez-Brandón M., Rousk J. & Bååth E. (2009) Adaptation of soil microbial communities to temperature: Comparison of fungi and bacteria in a laboratory experiment. Global Change Biology 15(12): 2950-2957.