This study examines the dynamics of mistletoe Viscum album ssp. austriacum infestation in Scots pine Pinus sylvestris stands within the Regional Directorate of State Forests (RDLP) in Krosno, southeastern Poland, over the period 2019−2025. The objective was to quantify changes in the area affected by mistletoe, evaluate temporal trends in, in mistletoe occurrence dynamics and forecast its development to 2030. The analysis was based on operational forest health monitoring data collected annually by eight Forest Districts (Kolbuszowa, Leżajsk, Lubaczów, Mielec, Narol, Oleszyce, Sieniawa, and Tuszyma). These records documented the area of pine stands with more than 10% crown coverage by mistletoe, assessed visually by trained forestry staff according to national monitoring standards. Although originally intended for operational purposes, the dataset provides consistent and comparable information suitable for identifying largescale temporal trends. Data were analysed using descriptive statistics, chain indices, and linear regression to assess interannual changes in infestation area. The results revealed a statistically significant linear increase (R2 =0.71, p<0.05) in mistletoe−infested pine stands across the RDLP in Krosno, from 2,097.63 ha in 2019 to 6,058.56 ha in 2025 – representing a 288% increase over the study period. The annual growth rate was estimated at approximately 540 ha per year. Spatial variability among forest districts was substantial: the most pronounced increases occurred in Kolbuszowa, Narol, and Leżajsk, where infestation expanded more than tenfold between 2022 and 2025. Districts that implemented more intensive mechanical removal in 2024 (e.g., Sieniawa, Leżajsk) showed stabilization or slight decreases in infested area, suggesting that consistent control measures can temporarily mitigate infestation growth. The regression−based projection predicts a continued expansion, potentially exceeding 8,300 ha by 2030 if current trends persist. These findings highlight the accelerating spread of mistletoe as a significant threat to pinedominated forest ecosystems in southeastern Poland, particularly under conditions of climatic stress and reduced host vitality. The results underline the necessity for systematic monitoring of parasitic species and adaptive forest management that integrates mistletoe risk assessment into planning frameworks. The study also demonstrates the value of operational State Forest data for ecological analyses and provides a quantitative foundation for regional strategies aimed at maintaining forest health and resilience in a changing climate.
Stopyra et al. (Thu,) studied this question.