A novel point-pattern reconstruction tool for simplified assessment of natural rejuvenation in forest stands based on small reference data sets: SIMPLY-REJUVE

• Applicant: Professorin Dr. Uta Berger
• Subject Area: Forestry ; Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 553265532

Due to its importance for the adaptation of forests to environmental changes and the resilience of forests to disturbances, natural regeneration has become a focus of ecological forest research. Despite recent technological developments, this remains a major challenge. In particular, very small plants with a height of less than 1.30 meters and correspondingly small diameters are difficult to identify using photogrammetric methods. However, manual inventory methods, such as the classic full inventory, are labor-intensive and too expensive to apply to large areas. The project aims to contribute to solving this problem by presenting a simulation tool for the reconstruction of point patterns and systematically analyzing its quality. It is based on a research approach that comprises three steps: (1) the collection of spatial data of all trees including the regeneration on a small subplot (= reference plot), (2) the collection of the overstory in the entire stand (= study plot) and (3) the reconstruction of the regeneration in the entire study area, assuming that the same relationships between the trees of the overstory and the regeneration exist everywhere as in the reference plot. This approach makes it possible to combine today's logistical possibilities: (a) the manual recording of regeneration on a small area is feasible, and (b) the inventory of the overstory using modern remote sensing or photogrammetric methods is relatively simple and less labor-intensive. By using an existing data set that is well known in forest science (the training basis will be the data set of the seasonal tropical rainforest of Barro Colorado Island (BCI) in Panama), the project can be limited to step (3). The aim is to systematically investigate the influence of a higher structural diversity and the size ratio of reference and prediction plots (= the entire study area) on the results of the point pattern reconstruction of regeneration plants (= understory) and which spatial statistics are particularly suitable for evaluating this influence quantitatively or qualitatively. The numerical methods are provided in a documented R-script (or R-package) as a reliable and efficient tool for forest ecology and forestry practice.

• DFG Programme: Research Grants