Recovery of terrestrial and marine communities in a New Zealand
fiord after large-scale disturbances.
The steep fiord landscape of New Zealand is prone to landslides.
These result in large scars in both terrestrial and marine communities
where the substratum has been scraped clean of most living organisms.
Species diversity and richness indices of terrestrial vegetation
and marine epibenthic communities were obtained from three such
scars of different age. Species composition and successional development
of the vegetation were compared to mature forest communities, and
to different landslide scars. Univariate and multivariate analyses
were used to quantify similarity/difference between sites.
Results from botanical observations showed that species diversity
and richness indices of the landslide scars were higher than those
of the mature forest community, even after 60 years of development.
The terrestrial vegetation showed a plateau in successional development
whereby scars of 34 and 60 years were similar in measues of richness
and diversity. Marine epibenthic communities showd no significant
differences in diversity, species richness or species composition
between disturbed and undisturbed sites.
Recovery of the terrestrial scar was initiated from the landslide
boundaries where pioneer species encroached onto the scar, in turn
producing favourable conditions for higher order plants. The period
of this progression appeared to be short (30 years). This was thought
to be facilitated by landslide debris that had collected in cracks
and crevices, as well as by islands of vegetation situate in the
middle of the scar that had been protected from the landslide by
the slope topography. Recovery of the marine scar was attributed
to recruitment of larvae from outside the affected area. This recovery
appeared to be rapid so that development of a mature community was
largely completed before this study was initiated.
Findings suggest that recovery of a terrestrial scar to a mature
forest would take in excess of 60 years to be completed but that
recovery of many components of marine epibenthic systems occurs
in less than 2 years. Landslides appear to be a major structuring
factor in terrestrial communities where such major catastrophes
occur infrequently. However, in marine epibenthic communities landslides
appear to be a relatively minor structuring factor where other types
of large-scale disturbances occur frequently.