Plantation density management as a tool to enhance the adaptability to climate change: a case study in ponderosa pine plantations in NW Patagonia, South America

FERNÁNDEZ M.E.; GYENGE, J.E.; VARELA S.; DE URQUIZA M.M.

Seúl, Corea

Congreso; XXIII IUFRO World Congress; 2010

IUFRO (International Union of Forest Research Organizations)

An ecophysiological study was carried out in Pinus ponderosa, in order to estimate the effect of different plantation densities (open and closed stands) on the response of this species to severe drought conditions. The following variables were studied: growth rate and period, sapflow density, water status, hydraulic conductance and conductivities, anatomy of new formed wood, water use efficiency (WUE). In spite that ponderosa pine is a summer-drought adapted species, high intraspecific competition severely affected growth (from 12 to 1 mm of dbh increase) as well wood quality. In this regard, C limitation led to the formation of thinner cell walls (with a similar lumen diameter) in the closed stand trees, maintaining similar proportion of early and latewood. Changes in growth period and magnitude can be explained by the different gas exchange rates between open and closed plantation trees, even before the decrease in soil water content was evident, indicating that chronic limitations are affecting productivity in the closed stand, even without water deficits. WUE was higher in the open stand trees compared to the closed stand. These results suggest that stand density management is a valuable tool to increase the adaptability of ponderosa pine to predicted conditions of climatic change.