『Abstract
This study quantifies progressive pedogenesis under a super-humid
climate on the west coast of South Island, New Zealand. It focuses
on soil morphology, pedogenic oxides, soil mass balance , phosphorus
transformation and linking pedogenesis trajectories to vegetation
communities. The study comprises a set of dune ridges of a coastal
sand dune complex covered by unmodified conifer (podocarp)-angiosperm
forest. The surface ages of the chronosequence range from 370
y to 6500 y. Rapid podzolisation is characteristic for the study
area. Within 1000 y, soils reach the Spodosol stage with typical
eluvial-illuvial horizons and mobilisation of Fe and Al. This
period is also characterised by the most rapid losses of total
phosphorus at a rate of 110 g m-2 ky-1,
a relative loss of 41％. Beyond 3000 y changes in soil chemistry
and losses for all nutrients markedly slow. Soil mass balance
shows that the 6500 y soil has lost 75％ total P, 62％ K, 52％ Ca
and 54% Na. Soil P fractions substantially change across the gradient.
High leaching losses of apatite and non-occulted P in the first
hundreds of years coincide with accumulation of organic and occluded
inorganic forms in the topsoil and subsoil, which mitigate total
P loss. Beyond 1000 y of pedogenesis, all P fractions decline
at similar rates to low, more persistent levels with apatite/non-occluded
P being the dominant P form after 6500 y of pedogenesis. This
incipient steady state is assumed to be sustained by the advection
of parent material-derived P through surface lowering and reduced
biological cycling. Vegetation communities change from more diverse
communities on young and less impoverished soils in the first
1000 y to less diverse and less variable communities beyond 1000
y of ecosystem development. The soil evolution-correlated vegetation
changes documented in this study are consistent with general schemes
of vegetation succession for the west coast of South Island.
Keywords: Chronosequence; Podzolisation; Vegetation communities;
Phosphorus; Mass balance; Holocene』
1. Introduction
2. Study area
3. Methods
4. Results
4.1. Soil morphological and physical properties
4.2. Chemical properties - pedogenesis indicators
4.3. Chemical mass balance analysis
4.4. Vegetation composition
5. Discussion
5.1. Podzolisation
5.2. Mass balance
5.3. Phosphorus chemistry
5.4. Vegetation communities
6. Conclusion
Acknowledgement
Appendix A. Supplementary data
References