Functional relationships with N deposition differ according to stand maturity in Calluna-dominated heathland.
Plant and soil bio(chemical) indicators are increasingly used to provide information on N deposition inputs and effects in a wide range of ecosystem types. However, many factors, including climate and site management history, have the potential to influence bioindicator relationships with N due to nutrient export and changing vegetation nutrient demands. We surveyed 33 heathlands in England, along a gradient of background N deposition (7.2-24.5 kg ha(-1) year(-1)), using Calluna vulgaris growth phase as a proxy for time since last management. Our survey confirmed soil nutrient accumulation with increasing time since management. Foliar N and phosphorus (P) concentrations in pioneer- and mature-phase vegetation significantly increased with N deposition. Significant interactions between climate and N deposition were also evident with, for example, higher foliar P concentrations in pioneer-phase vegetation at sites with higher temperatures and N deposition rates. Although oxidized N appeared more significant than reduced N, overall there were more, stronger relationships with total N deposition; suggesting efforts to control all emissions of N (i.e., both oxidized and reduced forms) will have ecological benefits.
Division of Biology, Imperial College London, Silwood Park, Ascot, Berkshire, SL5 7PY, UK, ajones@earthwatch.org.uk.
Alan Glyn
AG
Jones
Sally A
SA
Power
D000393:Air Pollutants / Q000378:metabolism*; D029795:Calluna / Q000254:growth & development / Q000378:metabolism*; D017753:Ecosystem; D004739:England; D004784:Environmental Monitoring; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D012989:Soil Pollutants / Q000378:metabolism*
D000393:Air Pollutants; D012989:Soil Pollutants; D010758:Phosphorus; D009584:Nitrogen