Functional ecology of Nothofagus pumilio regeneration in relation to light availability

MARTÍNEZ PASTUR G; LENCINAS MV; PERI PL.

Ciencia e Investigación Forestal

INFOR

Año: 2008 vol. 14 p. 43 - 53

0718-4530

The objeetive was to make a eomparative and lunetional approaeh analyzing morphologieal and physiologieal eharaeteristies 01 N. pumilio seedlings. growing in a pre-defined lighl gradienl under controlled conditions of ¡rrigalion and temperature. Seedlings of 2-3 years were collected in a closed canopy natural stand during September. Then, they were transferred to pats under a greenhouse, where three light levels were assayed (4%-26%-64% of the total natural incidentlight). Irrigation was made manually, maintaining a soil humidily 01 40-60% so;1 eapaeity. while lemperalure was eonlrolled through loroed ventilation (Iess than 24´C). Thirty six planls in 6 elusters per eaeh Irealment where measured during January (heighl, number, size and shape 01 leaves. braneh number and inserlion angle), while 6 plants (one per elusler) was seleeted lor physiologieal parameters measurement (dark respiration rate.lighl compensation poinI, photochem;cal effieieney,lighl saturation point and chlorophyll content). Photo-respiration was measured using an infra red gas analyzer 01 CO, model 5151 01 Qubit 5yslem Ine. wilh a leal ehamber 01 9 em´. Twenly-lhree variables related wilh three lunelionallevels (leal. shool and erown, whole planl) were analyzed.Al leaf level, mast of physiological variables were higher in luminous treatment. while biometric variables were higher in mlddle lighl trealmenl. This lasl lreatmenl has more ehlorophyll a-b (0.033 and 0.011 mg/em´), while luminous trealment has more earolenoids (0.010 mg/em´). However. dark lreatment presenled Ihe lower speeifie leal mass (0.0007 g/em´).At shoot and erown level, no differenees were found in branch number and insertion angle, bul plants growing in middle Iight trsalment were tallertllan the olhers (17 cm compared lo 12 cm). At whole planl level. best values were lound in middle lighl treatmenl. However, the higher leal area ralio was measured in dark trealmenl (389 em´lg). Nothofagus pumilio seedlings have morphological and physiological characteristics related to loleranl species, but eould quiekly ehange lo Ihose adapled lo inloleranl species when the Iighl availabilily ¡ncreases. It is necessary to make comparative and functional models to develap better silvicultural Irealmenls whieh maximize the seedling polenlial during Ihe installalion and ear1y growth phase.