Kirsty Havenga (2025) Rings of Time: dating thicket trees near Addo скачать в хорошем качестве

Kirsty Havenga (2025) Rings of Time: dating thicket trees near Addo

Aim. This study applies dendrochronological methods to estimate the minimum ages of selected thicket species. It also explores whether growth rings correlate with historical rainfall data. The species of interest include Portulacaria afra, Pappea capensis, and Euclea undulata. Location. The sample site is in Kirkwood, Eastern Cape, South Africa. Activities. For each species, the largest individuals were selected, and cross sections were collected using a chainsaw. Sections were sanded, and a representative portion of visible rings was mounted and polished. High-resolution scans were analysed in ImageJ to count and measure ring widths. This data was then processed in R. The growth ring trends were compared to 40 years of local CHIRPS precipitation data. General results indicate that Pappea capensis and Euclea undulata formed distinct annual growth rings, whereas growth ring boundaries are difficult to discern in Portulacaria afra because of ray tissue. Main Conclusions. The minimum ages for Pappea capensis range between 77 to 148 years. So far, correlation between ring-width trends and rainfall data are inconsistent across samples, as some samples have growth ring trends that align well with precipitation trends, whereas others do not. Research Implications. This will be discussed at the forum as the study is still ongoing.