Rapid transformation of P across a podzol chronosequence in Northern Sweden

Biological activity can accelerate soil processes and can thus have profound effects on weathering and the transformation of phosphorus (P). Here we show that the transformation of P is closely linked to soil development across an about 9000 years old soil chronosequence formed through glacial rebound. Easily weathered forms of P such as apatite are rapidly lost from the surface mineral horizon (within < 500 yrs) and these changes are coinciding with succession changes in the plant and microbial community structure. Long-term changes in P pools are, however, also dependent landscape topography. For instance, across a boreal landscape gradient, P concentrations increased dramatically in the surface soil of toe slope areas and decreased plant and microbial P availability [1, 2]. These differences are probably established already at early stages of soil formation. Also environmental disturbances, such as wildfires can have profound effects on the distribution of P. In the absence of wildfires organic P will build-up at the surface of the mineral soil whereas regular wildfires rather promote losses of P [3]. Despite large differences in fire frequency (40 to 5, 300 yrs since last fire) only small differences in the distribution of P forms in the surface soil were found in a wildfire chronosequence [3]. Possible adaptations to temporal and spatial variations in the P distribution will be discussed further.