New Zealand Journal of Botany abstracts
Plant succession and dune dynamics on actively prograding dunes,
Whatipu Beach, northern New Zealand
Andrew P. McK. Pegman*
G. L. Rapson†
Ecology Group
Institute of Natural Resources
Massey University
Private Bag 11222
Palmerston North, New Zealand
*Present address: 21 Victory Road, Laingholm, Auckland,
New Zealand.
†Author for correspondence. G.Rapson@massey.ac.nz
Abstract Whatipu Beach, north Manukau Harbour,
Auckland, has prograded episodically over 1.5 centuries. Sand dune
vegetation is quantitatively described, and related to successional
stage, local environment, and progradation dynamics. Foredunes, with
fine, mobile, infertile sand, occupy the most recently prograded areas
and are partially vegetated by native species. Instead of a dune slack,
a stream which changed course to flow between dune ridges has created
wet “sand river” vegetation. Relict foredunes and a dune slack persist
inland of the sand river, disrupting a lineal spatial sequence, as do
rear dune wetlands. Less-mobile grass and shrub communities, derived
from Ammophila arenaria dunes, occupy surfaces >50 years
old. No climax communities are present. In contrast to spatial
analogues, the Whatipu dunes demonstrate how rapidly succession
proceeds in response to the formation of new habitat, while freshwater
movements generate non-seral sand-river communities. Succession is
modified by invading exotics and by the absence of many
disturbance-intolerant native shrub species. Coastal progradation rates
at Whatipu indicate that shrubland develops within 50 years, suggesting
that spatial analogues of dune succession can mis-represent the
longevity of early seral stages. These unusual successional patterns on
dateable surfaces, and the presence of rare flora and fauna, make
Whatipu Beach important for conservation.
Keywords dune-slack; dynamic; sandplain; nutrient;
rare; foredune; linear succession; primary succession; secondary
succession; succession
B03039; Received 25 September 2003; accepted 22 November 2004;
Online publication date 17 March 2005
New Zealand Journal of Botany, 2005, Vol. 43: 223–244
0028–825X/05/4301–0223 © The Royal Society of New Zealand 2005
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