Comprehensive Analysis of Gap Formation in the Canopy of an Old-Growth Broadleaved Forest

We performed a quantitative and qualitative assessment of the dynamics of gap formation in the canopy of intact old-growth polydominant broadleaved forest in a permanent sample area in the Kaluga Zaseki Nature Reserve. Digital elevation models were obtained from aerial photography data of the forest in 2018 and 2021, from which gap schemas of several height classes were compiled. The resulting schemas were expertly analyzed using orthophotomosaic images, and the gap areas were estimated. A selective ground survey of gaps was carried out, and a regression analysis of the relationship between the relative gap area and the species composition of the stand based on the primary ground survey data was conducted. It was shown that the phenophase during the survey can significantly change the estimation of gap areas, and the height of the stand in the gap cannot serve as a reliable indicator of its age. It was also found that aerial photography reveals a more complex gap structure than ground-based surveys.