Tree size mostly drives the variation of xylem traits at the treeline ecotone

Abstract

At higher elevations and latitudes in the treeline ecotone, reduction in the heat accrued during the growing season is reflected in gradually decreasing tree size. Due to low temperatures, treeline trees might produce smaller xylem cells and, as a consequence, tree growth could be limited.

However, some xylem traits (i.e., cell lumen area) are considered relatively insensitive to climatic factors but highly dependent on tree size because of the natural widening of xylem conduits towards the stem base. We tested the hypothesis that earlywood cell lumen area is essentially invariant and depends largely on tree size.

Keywords

• Picea abies
• Picea engelmannii
• Pinus cembra
• Larix decidua
• stem allometry
• alpine treeline
• conduit diameter
• cell widening
• wood anatomy