Loss of nutrients due to litter raking compared to the effect of acidic deposition in two spruce stands, Czech Republic

Abstract

We evaluated how litter raking removed basic nutrients from forest soils by simulating this historical silvicultural practice on two spruce stands (Picea abies) in the Czech Republic. Experimental litter raking depleted the soil pool of exchangeable base cation nutrients (Ca2+, Mg2+ and K+) by up to 31% after the first litter raking in 2003. A second litter raking in the following year further reduced the soil pool by up to 16%, and the third litter raking in 2005 reduced the pool by up to 6% more. These losses of base cations were substantially greater than their annual input into the forest soil (estimated as from total atmospheric deposition and mineral weathering) as well as their annual runoff. The concentration of Mg and Ca in spruce needless decreased considerably within 3 years from the beginning of the experiment. In addition, the observed litter chemistry was used to estimate historical nutrient removal from litter raking by applying them to historical records of litter removal rates. According to these calculations, the annual loss of total Ca, Mg and K from spruce stands would be from 40% to 100% of its present annual input into the soil, and from 50% to 190% of annual runoff. On the basis of previous results estimated by geochemical modeling, we found that the loss of base cations due to litter raking was similar to their leaching due to acid deposition. We conclude that long-term removal of litter as widely practiced throughout the 19th century in Central Europe may have been responsible for a loss of base cations equivalent to that caused by acid deposition during the 20th century.