Cordilleran cypress´ (Austrocedrus chilensis (D. Don) Pic.Serm. & Bizzarri) adaptation potential to unfavorable hydric growth conditions

SERGENT AS; DALLA SALDA G; FERNÁNDEZ ME; MARTÍNEZ MEIER A

Berchtesgaden

Congreso; 21 Meeting ATSPB; 2016

Austrian Society of Plant Biology

The Cordilleran cypress (Austrocedrus chilensis (D. Don Pic.Serm. &Bizzarri) is a native conifer from Patagonia, South-America, with a largegeographical distribution, covering more than 1200 km (North-South) and astrong West to East precipitation gradient, demonstrating its capacity foradaptation to xeric conditions. Nevertheless its forests are one of the most threatenedecosystems of Patagonia, due to decline and mortality events observed duringlast decades when climatic variation and drought are considered as the maincontributing factors. Determining the adaptability to water stress of thesepopulations is crucial to preserve Cordilleran cypress forests. Stomatal conductance (n=30) and leaf waterpotential (n=75) were monitored in fifteen years old trees from fivepopulations during one growing season in a common garden. Monitoring was conductedduring 2014-2015 growing season, considered as the third driest season of the last58 years. Vulnerability to cavitation was determined by the air injectionmethod in branches (n=30). The hydraulic safety margin of each population wasassessed. Growth wasmeasured at the end of the 2015 and 2016 growingseasons. The results obtained showed that Cordilleran cypress can be consideredas an anisohydric - isohidrodynamic species. The minimum water potentialobserved was -2.9 MPa, whereas stomatal closure was observed at -1.5 MPa. Weobserved a relatively high resistance to cavitation, leading to differences inthe hydraulic safety margins between populations. A negative relationshipbetween drought resistance and growth potential was observed. These resultsshow Cordilleran cypress high tolerance to drought and lead to revise the assumptionsmade in the literature since it is described as a cavitation sensitive- droughtavoiding species. Significant differences were found between adaptive droughttraits demonstrating not only Cypress adaptation potential to unfavorablehydric growth conditions, but also the possibility to select appropriategenetic material for ecosystem restoration programs after forest decline orfire.