Canopy interception of nitrogen deposition in mountain forests: results from an above-canopy fertilization with labelled N
MetadataShow full item record
In the last few decades, the emission of reactive nitrogen (Nr) in the atmosphere through human activities hasstrongly raised, causing an increase in nitrogen (N) deposition, which has several potential effects on terrestrialecosystems, including forests. The growth of temperate and boreal forests is considered to be limited by N andtherefore the increasing availability of Nr may lead to an increase in forest productivity and C uptake, with apositive feedback on climate change mitigation potential of forest ecosystems. On the other hand, forest fertilisationexperiments have evidenced several negative consequences of increased N availability such as soil acidification,nutrient deficit, loss of biodiversity, increment in greenhouse gases emissions and an increase tree mortality. Mostof these studies have simulated N deposition by applying N fertilisation directly to the soil. This approach neglectsthe role of the canopy, which has been proved to influence the nitrogen use efficiency, other than the quantity andthe chemical form of the N deposition reaching the soil.For this reason, in 2014 a field-scale manipulation experiment was established in a temperate sub-mountain forestin Bolzano province, with the overall aim to evaluate the effects of nitrogen deposition on temperate forests byapplying aerial N fertilization over the tree canopy (NAB)and comparing it to the fertilization applied to theground (NBL). The fertilizations are applied monthly from May to September and the total N added correspondsto 20 kg N ha−1yr−1.To study the fate of the added N in both the fertilisation approaches, in July 2016 a fertilisation treatment wasperformed using isotopic labelled fertiliser (15NH154NO3). Labelled N was tracked throughout the ecosystem byanalysing its presence in the different ecosystem compartments (plants and soil). For this reason, samples of plantbiomass (fresh leaves, leaf litter and wood) and soil were sampled first in July 2016, 20 days after the fertilization,and successively at the beginning of March 2017, eight months after the fertilisation. The samples were analysedfor the15N isotopic signature (δ15N) with a continuous-flow isotopic ratio mass spectrometer coupled with anelemental analyser and the recovery of the added N was determined with an isotopic mass balance.In both fertilization approaches, most of the labelled N was recovered in the soil compartment. However, therecovering of fertilised-labelled N in plant tissues was much more in NABthan in NBLtreatment. This findingpoints out the importance of considering tree canopy in experiments simulating the effect of N depositions onforest ecosystems. However, considering the chronic nature of the N deposition process and the slowness by whichforest ecosystems can react to this type of perturbations, only manipulative long-term experiments can improveour understanding of the effect of N deposition on forest ecosystems.
Showing items related by title, author, creator and subject.
Does canopy mean nitrogen concentration explain variation in canopy light use efficiency across 14 contrasting forest sites? Peltoniemi M; Pulkkinen M; Kolari P; Duursma RA; Montagnani L; Wharton S; Lagergren F; Takagi K; Verbeeck H; Christensen T; Vesala T; Falk M; Loustau D; Makela A (2012)The maximum light use efficiency (LUE = gross primary production (GPP)/absorbed photosynthetic photon flux density (aPPFD)) of plant canopies has been reported to vary spatially and some of this variation has previously ...
Nitrogen deposition outweighs climatic variability in driving annual growth rate of canopy beech trees: Evidence from long-term growth reconstruction across a geographic gradient Gentilesca T; Rita A; Brunetti M; Giammarchi F; Leonardi S; Magnani F; van Noije T; Tonon G; Borghetti M (WILEY, 2018)In this study, we investigated the role of climatic variability and atmospheric nitrogen deposition in driving long-term tree growth in canopy beech trees along a geographic gradient in the montane belt of the Italian ...
Design and first tests of a vision system on a tele-operated vehicle for monitoring the canopy vigour status in orchards Bietresato M; Vidoni R; Gasparetto A; Mazzetto F (European Association of Geoscientists and Engineers, EAGE, 2015)A vision system able to give a punctual estimation of the canopy vigour (volume, leaves' chlorophyll content) of an orchard is a key-system for implementing Precision Agriculture. Indeed, such a system, composed by Lidar ...