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Tall shrublands persisted until 5000-6000 years ago, when increased
precipitation allowed a tall podocarp forest to develop,
at least in valley floors and on lower slopes. Beech forest
spread in higher altitudes, but shrubland remained a significant
component of regional vegetation. Between 800 and 1000
years ago all forest and tall shrubland was destroyed by anthropogenic
fires, and grassland and short shrubland again became
widespread.
McGlone et al. (1995) described pollen profiles from central
Otago sites that record the vegetation from the late Pleistocene
to the late Holocene. Between about 12,000 and 9000 years
ago, a low scrub (1-2 m high) of small-leaved and xerophytic
species formed a mosaic with Chionochloa grassland. Although
tall podocarp forest was established in coastal areas of
Southland and Otago by 9500 years ago, such forest is unlikely
to have existed in other than small isolated stands in the interior
before about 7500 years ago. The delay in forest establishment
there may be explained by a decrease in available water at that
time, either by lower rainfall or by a combination of increased
evapotranspiration (resulting from higher temperatures) and
decreased rainfall. The absence of, or very slow, peat deposition
during this interval seems to support a prevailing water
deficit. An abundance of tree-fern spores in the same period,
however, suggests water was not limiting, at least in sheltered
gullies. Frequent fires enabled the continued presence of tree
ferns by stopping the establishment of slower growing, firesensitive
podocarps, thus maintaining serai conditions.
About 7500 years ago a coniferous forest of Prumnopitys
taxifolia, Dacrycarpus dacrydioides, and Podocarpus abruptly
replaced lower altitude grassland communities, whereas Phyllocladus
alpinus Hook.fi and Halocarpus bidwilli (Hook.f. ex
Kirk) Quinn formed the upper treeline. The afforestation has
been attributed to increased precipitation and a slight decrease
in temperature. Nothofagus menziesii (Hook.f.) Oerst. became
established in the area about 6000 years ago, followed shortly
by a Nothofagus fusca type and Dacrydium cupressinum, although
Phyllocladus dominated pollen assemblages. Significant
percentages of pollen of shrub taxa such as Coprosma,
Asteraceae, and Poaceae indicate the continued presence of
grassland-shrubland communities above the treeline. After
3000 years ago, episodic destruction of podocarp forests by fire
resulted in a reduction in the frequency of some tree pollen, especially
Prumnopitys taxifolia, and an increase in grass pollen.
Forests were widely destroyed by anthropogenic fires, resulting
in a sudden proliferation of Pteridium esculentum (Forster f.)
Nakai spores and vastly increased amounts of charcoal about
600 years ago.
Avifaunal Changes
The composition of the Late Quaternary and Holocene avifauna
of terrestrial and inland wetland habitats is summarized
in Table 1 from data in Millener (1990), with alterations as elucidated
in Worthy (1993a, 1997) and Worthy and Holdaway
(1993, 1994a, 1996). The following notes support the numbers
of species listed herein as inhabiting such inland areas.
Pelecaniformes Only Pelecanus, Phalacrocorax carbo, and
P. melanoleucos are inland taxa.
Ciconiiformes Only Egretta alba, Botaurus stellaris, and Ixobrychus
novaezelandiae are inland taxa.
Anseriformes I do not accept Anas rhynchotis or Oxyura as
part of the prehuman fauna, Mergus was
coastal, and only Cnemiornis had endemic
species on each island.
Falconiformes Circus approximans is a recent immigrant, so
the prehuman fauna comprised one eagle,
one harrier, and one falcon.
Gruiformes The North and South Island pairs Aptornis
otidiformislA. defossor and P. mantellil
Porphyrio hochstetteri each consist of separate
species (Trewick, 1996); Porphyrio p.
melanotus is considered a recent immigrant;
Gallirallusphilippensis is recorded from glacial
deposits on South Island; and Porzana
tabuensis and P. pusilla, although rare as fossils,
are assumed to have been on both islands.
Charadriiformes Only Haematopus unicolor, Charadrius
bicinctus, Thinornis novaeseelandiae, Anarhynchus
frontalis, Coenocorypha aucklandica,
Himantopus novaezelandiae, Larus dominicanus,
L. bulleri, and Sterna albostriata
used inland areas habitually.
Passeriformes There are seven acanthisittid wrens, among
which Pachyplichas had discrete species on
each island and Dendroscansor decurvirostris
was endemic to South Island. The three
TABLE 1.—The number of species in each order of birds that inhabited
prehuman inland wetlands and/or terrestrial habitats on North and South
islands, New Zealand. Data is from Millener (1990), Worthy (1993a, 1997),
and Worthy and Holdaway (1993, 1994a, 1996).
Order
DiNORNITHIFORMES
APTERYGIFORMES
PODICIPEDIFORMES
PELECANIFORMES
CICONIIFORMES
ANSERIFORMES
FALCONIFORMES
GALLIFORMES
GRUIFORMES
CHARADRIIFORMES
COLUMB1FORMES
PSITTACIFORMES
CUCULIFORMES
STRIGIFORMES
CAPRIMULGIFORMES
CORACIFORMES
PASSERIFORMES
Total
North Island
7
2
2
3
3
11
3
1
9
9
1
5
2
2
1
1
20
82
South Island
9
3
2
3
3
11
3
1
8
9
1
5
2
2
1
1
20
84
Total
11
3
2
3
3
12
3
1
11
9
1
5
2
2
1
1
24
94