, 2003) in these sandy, acid mineral soils as they posses limited capacity to fix or adsorb organic P. The accelerated P loss from this system associated with excessive use of fire and secondary impacts mirror P dynamics in mature forest ecosystems entering late primary succession (Parfitt et al., 2005). The impact of this P loss could be significant. The open forest canopy in the spruce-Cladina forest provides limited throughfall. Phosphorus requirements for cyanobacterial N fixation are high ( Chapin et al., 1991) and feathermosses receive their P inputs from canopy throughfall ( Turetsky, 2003). These combined limitations would act as to reduce the presence and productivity of cyanobacteria
this website associated with feathermosses and ultimately lead to N limitation and decline in the presence and N2 fixation activity of feathermosses ( DeLuca and Zackrisson, 2007) thus limiting the capacity of the feathermosses to rebuild N capital on the spruce-Cladina forests. Extractable Mg was also notably reduced by years of burning. The mechanism for this loss is unclear as burning
would have concentrated alkaline metals in the ash layer (Neary et http://www.selleckchem.com/products/Y-27632.html al., 2005) and since there was no observable effect of burning on extractable Ca or total K (see Table 3). Again, it is possible that erosion of the ash layer and net leaching of Mg after fire events would potentially reduce extractable Mg in these sandy soils. The large differences in resin adsorbed NO3− is likely due to a reduced litter inputs into the degraded forests or perhaps due to the historic frequent burning and the visible accumulation of charcoal fragments in the O horizon. Charcoal presence in the mineral soil of frequently burned forest stands was significantly lower on average than
in the spruce-Cladina forests (see above); however, charcoal would have been more recently deposited in the O horizon and mineral soil ( DeLuca and Aplet, 2008). Charcoal presence in mineral soil and the O horizon has been observed to increase net nitrification ( DeLuca et al., 2006 and DeLuca and Sala, 2006) and result in an increased presence of ammonia oxidizing bacteria ( Ball et al., 2010). Zackrisson et al. (1996) found that charcoal Ponatinib expresses a capacity to adsorb organic compounds for approximately 100 years after the last fire event. This adsorption potential includes phenols and terpenes which are prevalent in forest ecosystems and have the potential to interfere with nitrification ( Uusitalo et al., 2008 and Ward et al., 1997). Therefore it is possible that the charcoal in the spruce-Cladina soils had been more recently deposited and still had the capacity to influence nitrification. Available organic C and N immobilization potential would have been greater in the reference forest given the notably deeper O horizon and greater C:N ratio which would result in more rapid immobilization of NO3−.