Temperate forest dynamics and carbon storage: A 26-year case study from Orange Kloof Forest, Cape Peninsula, South Africa

Abstract

Temperate forests are globally important carbon stores that are, in the face of recent improvements in their conservation, likely to increase their storage capacity in the future. Despite this, these ecosystems are poorly understood, especially over longer time periods. To remedy this and to better understand these important ecosystems, we monitored marked stems >5 cm diameter at breast height (DBH) in a 0.52 ha forest plot on the Cape Peninsula over 26 years. Aboveground biomass (AGB), calculated from stem diameter, increased from 203 to 226 Mg ha⁻¹ over this period. The AGB residence time was greater than a century. Stem mortality was relatively high (1.2% per annum [p.a.]) and exceeded recruitment (0.2% p.a.). The  recruitment of a large number of smaller stems of species not presently represented in the forest canopy suggests that compositional changes will occur in the future. Overall, these results suggest that the forest is in a post-disturbance recovery phase, although favourable climatic conditions over the last three decades may also have had an influence on AGB  accumulation.

Keywords: aboveground biomass, carbon sequestration, forest conservation,  long-term monitoring, succession