How Tree Decline Varies the Anatomical Features in Quercus brantii

Area of Science:

• Forestry
• Plant Anatomy
• Drought Stress Physiology

Background:

• Forest ecosystems worldwide face significant threats from drought.
• The Zagros Forest in Iran, home to Persian oak (Quercus brantii), is particularly vulnerable.
• Drought-induced decline impacts the health and survival of this dominant tree species.

Purpose of the Study:

• To investigate the anatomical structural changes in Persian oak trees experiencing drought stress.
• To compare the wood anatomy of healthy Persian oak trees with those showing signs of decline.

Main Methods:

• Sampled healthy and declined Persian oak trees from two forest sites in Ilam, Iran.
• Extracted wood discs at breast height and prepared sapwood sections.
• Measured anatomical characteristics: fiber length (FL), fiber wall thickness (FWT), number of axial parenchymal cells (NPC), ray number (RN), ray width (RW), and calcium oxalate crystals.

Main Results:

• Declined Persian oak trees exhibited significant differences in NPC, RN, FL, and FWT compared to healthy trees.
• Fiber wall thickness (FWT) increased in declined trees.
• The number of axial parenchymal cells (NPC) and ray number (RN) also increased in declined individuals.
• No significant difference was observed in the number of calcium oxalate crystals between healthy and declined trees.

Conclusions:

• Drought stress induces measurable anatomical alterations in Persian oak wood.
• These anatomical changes, including increased FWT and NPC, are indicative of drought's impact on tree physiology.
• Understanding these adaptations is crucial for managing Persian oak forests under increasing drought conditions.