Vitality versus cambium, xylem, and phloem characteristics in Cedrus libani

Abstract

Abstract In many regions, such as the Mediterranean, anticipated climate change is seen as a serious threat to tree vitality and forest productivity. Recent studies show that wood and bark structure as well as the number of dormant cambial cells bear valuable information about the growth condition and vitality of trees and thus could function as indicators to help manage forests in the future. Microcores and tree cores were sampled from stems of adult Cedrus libani trees growing at different altitudes in SW-Turkey. Trees were divided into two groups based on basal area increments: vital trees (positive growth trend), and trees of diminishing vitality (negative growth trend). Histological cross-sections were investigated for their number of dormant cambial cells as well as their xylem and phloem characteristics. We measured the widths of the conducting phloem, most recent xylem ring, earlywood, and latewood. We further calculated the ratio between the width of xylem ring and conducting phloem (XR:CPH ratio), and earlywood to latewood ratio. Vital trees had a significantly higher number of dormant cambial cells (on average 32%), higher xylem (67%), and conducting phloem (36%) widths, and a higher XR:CPH ratio (47%). The XR:CPH ratio ranged between 1.8:1 and 21.4:1. The number of dormant cambial cells was closely related to xylem and conducting phloem widths and showed a significant decrease with tree age. Altitude showed no direct effect on the measured and calculated parameters. Our results indicate the potential of dormant cambium, xylem, and phloem characteristics to assess the vitality and growth conditions of C. libani trees.