Soil solution and sugar maple response to NH(4)NO (3) additions in a base-poor northern hardwood forest of Québec, Canada.
Nitrogen additions (NH4NO3) at rates of three- and ten-fold ambient atmospheric deposition (8.5 kg ha(-1) year(-1)) were realised in an acid- and base-poor northern hardwood forest of Québec, Canada. Soil solution chemistry, foliar chemistry, crown dieback and basal area growth of sugar maple (Acer saccharum Marsh.) were measured. Except for a transitory increase of NO3 and NH4 concentrations, there was no persistent increase in their level in soil solution 3 years after N treatments, with the exception of one plot out of three, that received the highest N addition, beginning to show persistent and high NO3 concentrations after 2 years of N additions. Three years of N additions have significantly increased the N DRIS index of sugar maple but not N foliar concentration. Potassium, Ca and Mn foliar concentrations, as well as P and Ca DRIS indices, decreased in treated plots after 3 years. No treatment effect was observed for basal area growth and dieback rate. One unexpected result was the significant decrease in foliar Ca even in the treated plots that received low N rates, despite the absence of significant NO3-induced leaching of Ca. The mechanism responsible for the decrease in foliar Ca is not known. Our results, however, clearly demonstrate that increased N deposition at sites with low base saturation may affect Ca nutrition even when clear signs of N saturation are not observed.
Moore
Jean-David
JD
Direction de la recherche forestière, Forêt Québec, min. des Ressources naturelles et de la Faune, 2700 rue Einstein, Sainte-Foy, QC G1P3W8, Canada.
Houle
Daniel
D
D031002:Acer / Q000378:metabolism*; D002118:Calcium / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D009566:Nitrates / Q000032:analysis / Q000737:chemistry*; D011792:Quebec; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D014197:Trees
D009566:Nitrates; D012987:Soil; D012989:Soil Pollutants; D002118:Calcium; C006568:ammonium nitrate