###### Abstract  
The impact of lichens on the conservation of monuments, such as the World Heritage Site (WHS) of Cappadocian churches, presents a multifaceted challenge for conservators. Previous studies have shown that lichens can both induce deterioration processes of stone through their penetration into the substrate and chemical interactions as well as provide bioprotection, forming encrustations including calcium oxalate layers, which help mitigating the effects of weathering, reducing water penetration and eolian erosion. Evaluating the impact of lichens requires a comprehensive understanding of various factors, which include the type of rock substrate, the colonizing lichen species, the monument architecture, and the prevailing physic-chemical weathering processes. This study aims to provide a comprehensive analysis of the impact of lichen colonization on Saint Simeon Church in the Pasabag Valley (Turkey) with a multidisciplinary approach to investigate the interplay between lichens, microclimatic conditions, and the degradation of stone. Specifically, this study examines the influence of wind-driven rain (WDR) occurrences on lichen distribution and stone weathering to develop comprehensive conservation strategies. The results confirmed the previous observations and showed a prevalence of the protective role of lichens over their deterioration. The northwest side of the church, despite being heavily impacted by environmental factors such as WDR and freezing-thawing cycles, showed reduced deterioration due to extensive lichen coverage. In contrast, the northeast side, with lower lichen colonization, demonstrated more severe deterioration. These findings suggest that integrating the protective aspects of lichen colonization into conservation strategies can enhance their preservation. b 20  
induced deterioration processes, lichens can also offer bioprotection to stone surfaces by retaining moisture, enhancing waterproofing, and reducing thermal stress and erosion [2; 4; 5; 6; 7; 8]. Properly identifying lichen species and understanding the ecological factors that promote their growth makes it possible to evaluate their impact on stone monuments and assess their bioprotective effects [2; 8]. The unique Cappadocia monuments, known as \"fairy chimneys\", in Goreme National Park are located in Central Anatolia, Turkey, and belong to the World Heritage Sites (WHS) of UNESCO; they consist mainly of rock-hewn churches with significant wall paintings, attracting tourists from around the world. Unfortunately, these monuments are undergoing significant weathering processes due to the effects of shrinkage caused by temperature variations between night and day and during the seasons, as well as the various effects of driving rain and water penetration and also wind erosion, which lead to the wearing away of the tuff substrate [9; 10; 11; 12]. Several studies have been conducted to examine the physical and chemical weathering rates of these rock monuments to address future conservation projects, focusing on _in situ_ and in lab tests, such as wetting-drying and freezing-thawing, static rock, and slake durability [9; 10; 11; 12; 13; 14; 15]. Moreover, the biodeterioration aspect plays an important role, since these monuments are highly colonized by different epilithic and endolithic species [16; 17]. Cyanobacteria, meristematic fungi, and mosses have been detected, but the rock surfaces appear mainly covered by lichens, which varies depending on the monument surface exposure [17]. Their occurrence could significantly affect the monument conservation, since lichens can contribute to both physical and chemical weathering: their hyphae can penetrate rock surfaces, causing mechanical disintegration, while their metabolic activities can produce acids that chemically alter the rock [1; 2; 18; 19; 20; 21; 22; 23; 24]. However, their impact on the conservation of the Cappadocia monument is not clear or easy to assess.