title: Variation of mobile carbon reserves in trees at the alpine treeline ecotone is under environmental control.
abstract: In low temperature-adapted plants, including treeline trees, light-saturated photosynthesis is considerably less sensitive to temperature than growth. As a consequence, all plants tested so far show increased nonstructural carbohydrate (NSC) tissue concentrations when exposed to low temperatures. Reduced carbon supply is thus an unlikely cause for low temperature range limits of plants. For altitudinal treeline trees there is, however, a possibility that high NSC genotypes have been selected. Here, we explored this possibility using afforestations with single-provenance conifers along elevational gradients in the Southern Chilean Andes and the Swiss Alps. Tree growth was measured at each of four approximately equidistant elevations at and below the treeline. Additionally, at the same elevations, needle, branch and stem sapwood tissues were collected to determine NSC concentrations. Overall, growth decreased and NSC concentrations increased with elevation. Along with previous empirical and experimental studies, the findings of this study provide no indication of NSC reduction at the treeline; NSC increased in most species (each represented by one common population) towards their upper climatic limit. The disparity between carbon acquisition and structural carbon investment at low temperature (accumulation of NSC) thus does occur even among genotypes not adapted to treeline environments.
authors: Centro de Investigación en Ecosistemas de la Patagonia (CIEP) Conicyt-Regional R10C1003, Universidad Austral de Chile, Ignacio Serrano 509, Coyhaique, Chile.
authors: Alex
authors: A
authors: Fajardo
authors: Centro de Investigación en Ecosistemas de la Patagonia (CIEP) Conicyt-Regional R10C1003, Universidad Austral de Chile, Ignacio Serrano 509, Coyhaique, Chile.|Instituto de Ecología y Biodiversidad (IEB), Casilla 653, Santiago, Chile.
authors: Frida I
authors: FI
authors: Piper
authors: Institute of Botany, University of Basel, Schönbeinstrasse 6, CH-4056 Basel, Switzerland.
authors: Laura
authors: L
authors: Pfund
authors: Institute of Botany, University of Basel, Schönbeinstrasse 6, CH-4056 Basel, Switzerland.
authors: Christian
authors: C
authors: Körner
authors: Institute of Botany, University of Basel, Schönbeinstrasse 6, CH-4056 Basel, Switzerland.
authors: Günter
authors: G
authors: Hoch
mesh_terms: D000531:Altitude; D050260:Carbohydrate Metabolism; D002244:Carbon / Q000378:metabolism*; D002677:Chile; D017753:Ecosystem; D005843:Geography; D013045:Species Specificity; D013557:Switzerland; D014197:Trees / Q000254:growth & development / Q000378:metabolism*
chemical_list: D002244:Carbon