Comprehensive analysis of gap formation in the canopy of an old-growth broadleaved forest

Abstract

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 survey data of the forest in 2018 and 2021, from which gap diagrams of several elevation classes were constructed. The resulting schematics were expertly analyzed using orthophotomosaic survey data and gap areas were estimated. We conducted a sample ground survey of gaps and regression analysis of the relationship between relative gap area and stand species composition from the primary enumeration data. It was shown that the phenophase at the time of the survey can significantly change the estimate 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.