New Zealand Journal of Botany abstracts
Ecology and conservation status of three “spring annual” herbs in dryland
ecosystems of New Zealand
Geoffrey Rogers
Science & Research Unit
Science, Technology and Information Services
Department of Conservation
P.O. Box 5244
Dunedin, New Zealand
Susan Walker
Landcare Research
Private Bag 1930
Dunedin, New Zealand
Michael Tubbs
Department of Conservation
P.O. Box 176
Alexandra, New Zealand
Jim Henderson
Department of Conservation
P.O. Box 8
Arthur’s Pass, New Zealand
Abstract The biological and ecological significance
of the “spring annual” life-history strategy in the New Zealand flora is
examined for Myosurus minimus subsp. novae-zelandiae (Ranunculaceae),
Ceratocephala pungens (Ranunculaceae), and Myosotis pygmaea
var. minutiflora (Boraginaceae) in terms of their biogeographies,
habitats, population sizes, seed morphologies, plant communities, and relationships
with co-occurring exotic taxa. All three have predominantly eastern South
Island and lower North Island distributions, two have contracted modern ranges,
and all extant populations are centred on Central Otago. The ephemeral wetland
habitat of Myosurus, the “desert” pavement habitat of Ceratocephala,
and the turf and gravel habitat surrounding water bodies of Myosotis
all share a strong summer soil-moisture deficit. These genuine non-forest
habitats are compared with farming-induced scabweed or mat vegetation on
dry hillslopes as additional facultative habitat for all three taxa. Selection
for this growth strategy probably accompanied mountain building in the mid
to late Cenozoic with the creation of seasonally dry eastern climates. Small
numbers of sites, small population sizes, and habitat vulnerability to weeds
and land conversion result in a conservation status of “threatened” for all
three taxa. The problem of nesting conservation goals and management strategies
for spring annual habitat within the restoration goals for their surrounding,
degraded dryland ecosystems is highlighted.
Keywords annual plants; spring annuals; New Zealand;
Myosurus; Myosotis; Ceratocephala
B01060 Received 11 December 2001; accepted 22 August 2002; published 28
November 2002
New Zealand Journal of Botany, 2002, Vol. 40: 649-669
0028-825X/02/4004-0649 $7.00 © The Royal Society of New Zealand
2002
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