Monitoring Seasonal Changes in Tree Phenology using Repeat Photography: A Case Study at Süleyman Demirel University, Isparta, Türkiye
Candan Kus Sahin *
Department of Landscape Architecture, Architecture Faculty, Suleyman Demirel University, Isparta, Türkiye.
*Author to whom correspondence should be addressed.
Abstract
In this study, one of the basic and conventional phenological observations was made using repeated ground-based in-situ visual monitoring and repeat photography in the period of April 5,2024 through January 17, 2025. It was assumed that those methodologies may provide a unified phenological observation network. A 7-scale assessment ranking system was introduced for evaluating phenological modifications throughout the study. However, clear phenological phase differences were observed for selected four tree species of Silver Birch (Betula pendula; I and II), Corkscrew Willow (Salix matsudana; III), Manna Ash (Fraxinus ornus; IV), and Silver Linden (Tilia tomentosa; V) that were found in a roadside of Suleyman Demirel University campus in Isparta,Türkiye . It was realized that Corkscrew Willow shows leaf out approximately 15 days earlier than the other selected species in April 2024. Moreover, foliage appearance properties were ranked 6 for all those samples from April 24 through August 1. Silver Birches reveal a higher sensitivity to atmospheric conditions, which was evidence for entering into the maturity phase earlier than all three-other species. It is noticeable that up to September 19, Manna Ash and Silver Linden revealed only various shades of green colors on their canopy. Regarding those specific appearances, Corkscrew Willow, Manna Ash and Silver Linden were ranked 6 from May 21 through September 19, while Silver Birch trees were ranked 6 until August 1, then ranked 5 after that. It is worth noting that selected two Silver Birch species show all the leaves fallen on November 7 (entering dormant phase), but after November 13, Manna Ash and Silver Linden show the majority of leaves fallen. Corkscrew Willow appears to be still in maturity phase until November 20 and then enters senescent phase, following the dormant phase after December 13. The ground-based phenological observations and repeated photography in-situ evaluations may be useful in cost and time-effective methods for studying autumn coloration of certain deciduous plants.
Keywords: Autumn coloration, deciduous trees, repeat photography, phenology, silver birch, corkscrew willow, manna ash, silver linden