Changes in soil carbon and nutrients following 6 years of litter removal and addition in a tropical semi-evergreen rain forest

Edmund Vincent John Tanner, Merlin W. A. Sheldrake, Benjamin L. Turner
2016 Biogeosciences  
<p><strong>Abstract.</strong> Increasing atmospheric CO<sub>2</sub> and temperature may increase forest productivity, including litterfall, but the consequences for soil organic matter remain poorly understood. To address this, we measured soil carbon and nutrient concentrations at nine depths to 2<span class="thinspace"></span>m after 6 years of continuous litter removal and litter addition in a semi-evergreen rain forest in Panama. Soils in litter addition plots, compared to litter removal
more » ... ts, had higher pH and contained greater concentrations of KCl-extractable nitrate (both to 30<span class="thinspace"></span>cm); Mehlich-III extractable phosphorus and total carbon (both to 20<span class="thinspace"></span>cm); total nitrogen (to 15<span class="thinspace"></span>cm); Mehlich-III calcium (to 10<span class="thinspace"></span>cm); and Mehlich-III magnesium and lower bulk density (both to 5<span class="thinspace"></span>cm). In contrast, litter manipulation did not affect ammonium, manganese, potassium or zinc, and soils deeper than 30<span class="thinspace"></span>cm did not differ for any nutrient. Comparison with previous analyses in the experiment indicates that the effect of litter manipulation on nutrient concentrations and the depth to which the effects are significant are increasing with time. To allow for changes in bulk density in calculation of changes in carbon stocks, we standardized total carbon and nitrogen on the basis of a constant mineral mass. For 200<span class="thinspace"></span>kg<span class="thinspace"></span>m<sup>−2</sup> of mineral soil (approximately the upper 20<span class="thinspace"></span>cm of the profile) about 0.5<span class="thinspace"></span>kg<span class="thinspace"></span>C<span class="thinspace"></span>m<sup>−2</sup> was "missing" from the litter removal plots, with a similar amount accumulated in the litter addition plots. There was an additional 0.4<span class="thinspace"></span>kg<span class="thinspace"></span>C<span class="thinspace"></span>m<sup>−2</sup> extra in the litter standing crop of the litter addition plots compared to the control. This increase in carbon in surface soil and the litter standing crop can be interpreted as a potential partial mitigation of the effects of increasing CO<sub>2</sub> concentrations in the atmosphere.</p>
doi:10.5194/bg-13-6183-2016 fatcat:nmy5emckfrfkho2hr4fhaa54hy