Above- and belowground nutrients storage and biomass accumulation in marginal Nothofagus antarctica forests in southern Patagonia

PERI, PABLO LUIS; GARGAGLIONE, V.; MARTÍNEZ PASTUR, G.

FOREST ECOLOGY AND MANAGEMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2008 p. 2502 - 2511

0378-1127

The above- and belowground biomass and nutrient content (N, P, K, Ca, S and Mg) of pure deciduous Nothofagus antarctica (Forster f.) Oerstedstands grown in a marginal site and aged from 8 to 180 years were measured in Southern Patagonia. The total biomass accumulated ranged from60.8 to 70.8 Mg ha1 for regeneration and final growth stand, respectively. The proportions of belowground components were 51.6, 47.2, 43.9 and46.7% for regeneration, initial growth, final growth and mature stand, respectively. Also, crown classes affected the biomass accumulation wheredominant trees had 38.4 Mg ha1 and suppressed trees 2.6 Mg ha1 to the stand biomass in mature stand. Nutrient concentrations varied accordingto tree component, crown class and stand age. Total nutrient concentration graded in the fallowing order: leaves > bark > middle roots > smallbranches > fine roots > sapwood > coarse roots > heartwood. While N and K concentrations increased with age in leaves and fine roots,concentration of Ca increased with stand age in all components. Dominant trees had higher N, K and Ca concentrations in leaves, and higher P, Kand S concentrations in roots, compared with suppressed trees. Although the stands had similar biomass at different ages, there were importantdifferences in nutrient accumulation per hectare from 979.8 kg ha1 at the initial growth phase to 665.5 kg ha1 at mature stands. Nutrient storagefor mature and final growth stands was in the order Ca > N > K > P > Mg > S, and for regeneration stand was Ca > N > K > Mg > P > S.Belowground biomass represented an important budget of all nutrients. At early ages, N, K, S, Ca and Mg were about 50% in the belowgroundcomponents. However, P was 60% in belowground biomass and then increased to 70% in mature stands. These data can assist to quantify theimpact of different silviculture practices which should aim to leave material (mainly leaves, small branches and bark) on the site to amelioratenutrient removal and to avoid a decline of long-term yields.