Carbon accumulation along a stand development sequence of Nothofagus antarctica forests across a gradient in site quality in Southern Patagonia.

PL PERI; V GARGAGLIONE; G MARTÍNEZ PASTUR; MV LENCINAS

FOREST ECOLOGY AND MANAGEMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2010 p. 229 - 237

0378-1127

Native forests are considered efficient carnon (C) sink ecosystems being Nothofagus antarctica (Forster f.) Oersted one of the main deciduous native species in the Patagonian region (Argentina). Above- and below-ground C pools were measured in pure even-aged stands at different ages (5 to 220 years), crown and site classes. Mean tissue C concentration varied from 46.3% in medium roots of dominant trees to 56.1% in rotten wood for trees grown in low quality sites. Total C concentration generally graded in the following order: heartwood > rotten wood > sapwood > bark > small branches > coarse roots > leaves > medium roots > fine roots. Functions were fitted for total C accumulation, and root/shoot ratio of individual trees against age. Total C accumulated for mature dominant trees was six times greater than suppressed trees, and total C accumulated by mature dominant trees grown at the best evaluated site was doubled than those in the worse site. Also, crown classes and site quality affected the moment of maximum C accumulation, eg. while dominant trees grown in the worse site was 0.73 kg C tree-1 year-1 at 139 years, in the best site was 1.44 kg C tree-1 year-1 at 116 years . In all site qualities, C root/shoot ratio decreased over time from a maximum value of 1.3-2.2 at 5 years to a steady-state asymptote of 0.3-0.7 beyond 60 years of age. Thus, root C accumulation was greater during the regeneration phase and for trees grown in worse site qualities. The equations developed for individual trees have been used to estimate stand C accumulation from forest inventories data. Total stand C ranged from 128.0 to 350.9 Mg C ha-1, where soil C pool represented 52-73% of total ecosystem C depending on age and site classes. Proposed equations can be used for practical purposes such as to estimate the impact of silvicultural parctices (thinning, silvopastoral systems) on forest C storage or to evaluate the development of both above- and belowground C over the forest life cycle for different site qualities for accurate quantification of C pools on regional scale.