RESEARCH
canopy and soil nitrogen manipulation experiments in a beech forest in italy
Photo of one of the 3 plots subjected to the N60 treatment
Photo of one of the 3 plots subjected to the N30A treatment
Funding
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THE CANSIGLIO FOREST
The nitrogen (N) manipulation experiment has been established in 2015 in a mature beech forests (average age 120-140 years old) located on the Eastern Alps (Cansiglio; 46° 3′ 19” N 12° 22′ 51′′ E, 1100 m a.s.l.), close to the ICP Forest Level 2 permanent monitoring plots (VEN1 - Pian del Cansiglio), where climate and atmospheric deposition have been carried out since 1996. The area is characterised by an oceanic climate, with mean annual temperature of 7 °C, mean annual precipitation over 1700 mm, with no summer drought. Cansiglio forest grows on a calcareous pedogenetic substrate (Haplic Luvisol). The natural atmospheric N deposition is between 17.7 (bulk deposition) and 12.6 (throughfall) kg ha-1 yr-1. The forest is within the Campo Di Mezzo Biogenetic Nature Reserve – Pian Parrocchia, managed by the Carabinieri Biodiversity Group.
THE EXPERIMENT
Four different treatments have been carried out since 2015: control (only ambient deposition), canopy N addition, N30A (ambient deposition + 30 kg ha-1 yr-1 sprayed over tree canopies), soil N additions, the latter including two different doses, i.e., N30 (ambient deposition +30 kg ha-1 yr-1) and N60 (ambient deposition + 60 kg ha-1 yr-1). While the N30 and N30A treatments fall within the range of predicted N deposition scenarios for 2050 (~ 12–24 kg N ha-1 yr-1; Phoenix et al., 2006 Glob. Chang. Biol. 12, 470–476) and the range of N deposition measured in other Mediterranean areas (up to 45 kg kg ha-1 yr-1; Fenn et al., 2003 BioScience, 53 (4), 404–420), the N60 treatment was considered to monitor ecosystem responses under excess N conditions and hence N saturation (Aber et al. 1998 BioScience 48 (11), 921-934).
N has been applied as an ammonium nitrate solution (NH4NO3), equally distributed in three applications during the growing season (June, July, and September). Because of the small amount of water added (< 1 mm yr−1) compared to the natural input from precipitation, no wet control was included. The experiment is arranged in a completely randomised design with three plots for each treatment. The plots in the control and soil treatments have dimensions of 30 × 30 m, whereas plots in the N30A are circular, with a ray of 30 m. To avoid any lateral contamination effects, a central area (15 × 15 m) within each plot was established for intensive monitoring of different tree and soil parameters, i.e., tree stem growth, foliar and tree ring d13C (to assess water-use efficiency), foliar nutrients (see Teglia et al. 2022 Science of The Total Environment 834, 155362), forest productivity (see Ravaioli et al. 2022 L'Italia forestale e montana 77 (1), 35-4) and d15N along the forest profile to assess ecosystem nitrogen dynamics (Teglia et al. in preparation). Since summer 2024, the site has been equipped with TreeTalkers (Natura 4.0) for monitoring continuously tree growth and transpiration; sensors for dry deposition will be installed soon. Current collaborators at the site: Dario Ravaioli, Comando Carabinieri Forestali Vittorio Veneto and Carabinieri Biodiversity Group.
Former collaborators: Alessandra Teglia, Graziella Marcolini, Enrico Muzzi and several master and undergraduate students. Interested in collaborations at out experimental sites? Get in touch with me (co-PI) or Federico Magnani (PI)! |