Nutritional status of Abies pinsapo forests along a nitrogen deposition gradient: do C/N/P stoichiometric shifts modify photosynthetic nutrient use efficiency?

• Published in: Oecologia Vol. 171; no. 4; pp. 797 - 808
• Main Authors: Blanes, Ma Carmen, Viñegla, Benjamín, Merino, José, Carreira, José A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer 01.04.2013; Springer-Verlag; Springer Nature B.V
• Subjects: Abies - chemistry; Abies - physiology; Abies pinsapo; Analysis of Variance; Animal and plant ecology; Animal, plant and microbial ecology; Biogeochemical cycles; Biological and medical sciences; Biomedical and Life Sciences; Carbon - metabolism; Coniferous forests; Ecology; Forest ecosystems; Forest soils; Forestry; Forests and forestry; Fundamental and applied biological sciences. Psychology; General aspects; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Hydrology/Water Resources; Image Processing, Computer-Assisted; Leaves; Life Sciences; Mass Spectrometry; Nitrogen; Nitrogen - metabolism; Nutrient use efficiency; Nutritional Physiological Phenomena - physiology; Phosphorus - metabolism; Photosynthesis; Photosynthesis - physiology; PHYSIOLOGICAL ECOLOGY; Physiological ecology - Original research; Phytochemistry; Plant Leaves - chemistry; Plant Leaves - physiology; Plant nutrition; Plant Sciences; Plants; Spain; Trees; Trees - chemistry; Trees - physiology; C exchange; Foliar nutrient stoichiometry; Photosynthesis; N saturation; P limitation; Exchange; Stoichiometry; Forests; Atmospheric fallout; Nutrient; Nitrogen; Nutritional status
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-012-2454-1

Chronic atmospheric N deposition has modified relative N availability, altering the biogeochemical cycles of forests and the stoichiometry of nutrients in trees, inducing P limitation, and modifying the N:P ratios of plant biomass. This study examines how the variation in the foliar stoichiometry of Abies pinsapo across an N deposition gradient affects foliar traits and photosynthetic rate. We measured the maximum net assimilation rates (A max ) and the foliar nitrogen (N) and phosphorus (P) concentrations in A. pinsapo needles of five age classes. The leaf mass per area and photosynthetic N and P use efficiencies (PNUE and PPUE, respectively) were also estimated. The results from the N-saturated stand (Sierra Bermeja, B) differed from the comparable N-limited stands under investigation (Yunquera, Y, and Sierra Real, SR). The trees from Y and SR exhibited a reduction in the N content in older needles, whereas the foliar N concentration at the B site increased with needle age. N and P were positively correlated at Y and SR, but not at B, suggesting that the overload of N in the trees at site B has exceeded the homeostatic regulation capacity of the N-saturated stand in terms of foliar stoichiometry. A max and PNUE were correlated positively with P and negatively with the N/P ratio at the three study sites. The foliar N concentration was positively correlated with A max at Y and SR. However, this relationship was negative for the B site. These findings suggest that the nutritional imbalance caused by increased chronic deposition of N and an insufficient supply of P counteracts the potential increase in net photosynthesis induced by the accumulation of foliar N.