Trees increase their P:N ratio with size
Sardans i Galobart, Jordi (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Peñuelas, Josep (Universitat Autònoma de Barcelona. Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia)

Data:	2015
Resum:	Aim: Phosphorus (P) tends to become limiting in ageing terrestrial ecosystems, and its resorption efficiency is higher than for other elements such as nitrogen (N). We thus hypothesized that trees should store more P than those other elements such as N when tree size increases and that this process should be enhanced in slow-growing late-successional trees. - Location: Catalan forests. -Methods: We used data from the Catalan Forest Inventory that contains field data on the P and N contents of total aboveground, foliar and woody biomasses of the diverse mediterranean, temperate and alpine forests of Catalonia (1018 sites). We used correlation and general linear models to analyse the allometric relationships between the nutrient contents of different aboveground biomass fractions (foliar, branches and stems) and total aboveground biomass. - Results: Aboveground forest P content increases proportionally more than aboveground forest N content with increasing aboveground biomass. Two mechanisms underlie this. First, woody biomass increases proportionally more than foliar biomass, with woody biomass having a higher P:N ratio than foliar biomass. Second, the P:N ratio of wood increases with tree size. These results are consistent with the generally higher foliar resorption of P than of N. Slow-growing species accumulate more total P aboveground with size than fast-growing species, mainly as a result of their large capacity to store P in wood. - Main conclusions: Trees may have developed long-term adaptive mechanisms to store P in biomass, mainly in wood, thereby slowing the loss of P from ecosystems, reducing its availability for competitors and implying an increase in the P:N ratio in forest biomass with ageing. This trend to accumulate more P than N with size is more accentuated in slow-growing, large, long-lived species of late successional stages. In this way they partly counterbalance the gradual decrease of P in the soil.
Ajuts:	European Commission 610028 Ministerio de Ciencia e Innovación CSD2008/00040 Ministerio de Economía y Competitividad CGL2013-48074-P Agència de Gestió d'Ajuts Universitaris i de Recerca 2014/SGR-274
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió sotmesa a revisió
Matèria:	Early-successional species ; Forest ; Late-successional species ; Leaf ; Wood ratio ; N:P ; Nitrogen ; Phosphorus ; Soil ; Stoichiometry
Publicat a:	Global ecology and biogeography, Vol. 24, Issue 2, p. 147-156 (Feb. 2015) , ISSN 1466-822X

DOI: 10.1111/geb.12231
PMID: 25983656

Submitted version 28 p, 1.3 MB

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