Variations in Wood Density, Annual Ring Width and Vessel Properties of Quercus brantii Affected by Crown Dieback

Forough Soheili,Stephen Woodward,Hazandy Abdul-Hamid,Hamid Reza Naji,Isaac Almasi

doi:10.3390/f12050642

Forough Soheili, Stephen Woodward + Show 3 more

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https://doi.org/10.3390/f12050642

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Abstract

Tree decline due to climate change results in physiological weaknesses, attacks by harmful pests and pathogens and threats to forest ecosystem stability. In the work described here, the effects of drought on wood density, tree ring width and variations in vessel morphology are investigated in Persian oak (Quercus brantii) in the forest of the Zagros Mountains, Ilam Province, western Iran. Discs are cut from trunks of declined and healthy trees and woodblocks are cut radially from the sapwood near the bark, at a mid-point between the vascular cambium and the pith (middle) and from wood near the pith. Observations are made on transverse sections from the blocks using microscopy. In trees with decline symptoms, wood density is greater than in healthy trees. Furthermore, declining trees have the narrowest ring width, reduced vessel diameter and area and the highest numbers of vessels and tylose in pith towards the bark. It is concluded that changes in anatomical features are associated with the weakening of trees and are components of declining tree health.

Highlights

Forest dieback is a complex phenomenon characterized by decreasing tree growth, defoliation and change in leaf size, shape and color, leading to the immediate or gradual death of trees [1]
The oven-dry wood density index (WD) of declined trees was higher than the WD in healthy trees (Table 3)
A decreasing trend in WD from near-pith to nearbark was found in declined trees sampled in all three areas

Summary

Introduction

Forest dieback is a complex phenomenon characterized by decreasing tree growth, defoliation and change in leaf size, shape and color, leading to the immediate or gradual death of trees [1]. Decline and mortality of oak species have been reported for more than a century [2], sometimes occurring in vast areas of forest due to complex and interacting reactions involving environmental stresses, pests and diseases [3]. Forest decline has been reported in this oak forest and is resulting in extensive tree mortality [4]. The impacts of climate change on the Zagros oak forest have led to serious forest disturbance, including dust storms, fires and pest and disease outbreaks, leading to a decline in the main forest tree species of the region [5]. For example, can provide valuable information about the responses of trees to past environmental events [8,9]

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