Abstract
Increasing atmospheric CO2 concentration and nitrogen deposition are, among the global change related drivers, those playing a major role on forests carbon sequestration potential, affecting both their productivity and water-use efficiency. Up to now, results are however contrasting, showing that the processes underlying them are far from being fully comprehended. In this study, we adopted an innovative approach to simulate the increase of N deposition in a sessile oak forest in North-Eastern Italy, by fertilizing both from above and below the canopy. We observed the dynamics of basal area increment, intrinsic water-use efficiency and of several leaf functional traits over 4 years, to evaluate how the added nitrogen and the two different fertilization system could affect them. We were not able, however, to detect any shift, besides a common yearly variability related to a prevailing background environmental forcing. To this end, we considered as relevant factors both the short time-span of the observation and the relatively low rate of applied nitrogen. Therefore, we stress the importance of long-term, manipulative experiments to improve the understanding of the C sequestration and mitigation ability of forests in response to increased N deposition.
Highlights
Atmospheric carbon dioxide concentration (Ca) increase and nitrogen (N) depositions are considered among the climate change-related drivers that play a major role on forest productivity and carbon (C) sequestration potential [1,2]
Nitrogen oxides (NOx ) emitted during fuel combustion and ammonia volatilization resulting from intensive agriculture have increased atmospheric N deposition, mostly as NO3 − and NH4 +, especially in the Northern
The correlation matrix shows a significant relation between intrinsic water-use efficiency (iWUE) and leaf area index, (LAI), as well as between LAI and canopy N content and relative leaf N concentration (Table 1)
Summary
Atmospheric carbon dioxide concentration (Ca) increase and nitrogen (N) depositions are considered among the climate change-related drivers that play a major role on forest productivity and carbon (C) sequestration potential [1,2]. Evidences on the effect of rising CO2 levels on forest productivity, as well as on the intrinsic water-use efficiency (iWUE) of trees are still contrasting. Several authors reported a positive relationship between forest growth and iWUE [3,4,5]. Nitrogen oxides (NOx ) emitted during fuel combustion and ammonia volatilization resulting from intensive agriculture have increased atmospheric N deposition, mostly as NO3 − and NH4 + , especially in the Northern. Concerning the effect of atmospheric N deposition on forest ecosystem, contrasting results are reported in the literature. Other authors have shown an important stimulating effect of N
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
