Long-term forest dynamics on Mt. Hauhungatahi, New Zealand: a forest-landscape simulation study
2 School of Environment & School of Biological Sciences, The University of Auckland, New Zealand
3 Ecological Modelling, UFZ Helmholtz Centre for Environmental Research, Leipzig, Germany
P 3.6 in Ökosysteme: Funktion und Leistungen
Palaeoecological records imply that catastrophic, landscape-level disturbances are major drivers controlling long-term dynamics of New Zealand's forests. However, the effects of multiple factors (e.g. climatic variation, disturbance, human influence) confound the interpretation of these palaeoecological records. Using the forest landscape model LandClim, we aim to simulate the long-term forest dynamics under controlled environmental conditions and compare results to palaeoecological findings. For this purpose, the well-investigated western slope of Mt. Hauhungatahi in the central North Island was used as a case study for examining forest succession after large scale stand replacing disturbances, in this case the Taupo eruption of c. 1700 BP, and the subsequent emergence of altitudinal species zonation. Model results were in close agreement with key empirical patterns seen in pollen reconstructions and contemporary vegetation studies along the altitudinal transect. The modelled successional sequence displayed a major shift in forest composition between simulation years 400 to 1000 after the Taupo eruption, when the dense initial stands of conifers (dominated mainly by Libocedrus bidwillii) were progressively replaced by the angiosperm Weinmannia racemosa in the montane forest. From around year 1000 onwards, the current altitudinal species zonation was attained. Our simulation study therefore suggests that LandClim provides a suitable framework for investigating the role of spatial processes, in particular disturbance, in New Zealand’s forest landscapes.