The biota and geology of Ngārango Otainui: A mixed indigenous / naturalised vegetation association of the Māngere Inlet, Manukau Harbour
- Author:
- de Lange P.J., Marshall A.J., Schmid L.M.H., & Graham S.
- Year:
- 2022
- Journal:
- Perspectives in Biosecurity
- Pages:
- 7: 5–33
- Url:
- https://doi.org/10.34074/pibs.00702
An account of the geology, vegetation associations,
mycobiota, flora and avifauna of Ngārango Otainui, a
0.309 ha island located at the eastern end of the Māngere
Inlet, Manukau Harbour, Tāmaki Makaurau / Auckland is
provided. This appears to be the first comprehensive
account of the island’s geology, vegetation and biota.
The island has been mapped by others as Puketoka
Formation; our survey confirmed this, noting that the
basal exposed portion of the island appears to be
a distal, heavily weathered ignimbrite over which is
deposited a series of tephras (Hamilton Ashes). The flora
and mycobiota of the island, assessed over three visits
(2009 and 2021) recorded 125 taxa from 57 families
and 100 genera from Ngārango Otainui, and vouchers
for 119 (95%) of these obtained. Fifty-two (54%) of the
vascular plants and four (36%) of the bryophytes are
naturalised to New Zealand and most of these dominate
the island’s vegetation. Earliest imagery (1940) available
suggests that the island was then dominated by
grassland, and that since then the island has developed
a woody vegetation dominated by naturalised plants,
mostly from dispersal from nearby Auckland City urban
sources. Fourteen of these plants are regarded as pest
species within the Auckland Council Region. During two
visits (January and November 2021) 14 species of bird
were noted on or around the island. While no nationally
threatened taxa were found, one plant, Bromus arenarius,
five lichens and three birds seen are listed as ‘At Risk’
by threat listing panels using the New Zealand Threat
Classification System. Nine vegetation associations (and
sparsely vegetated landforms) were recognised. These
are described in this paper and their extent given and
mapped. Since aerial imagery became available for the
island, 55% of the island has been lost through erosion,
which is ongoing.
Keywords: Ngārango Otainui; Māngere Inlet; Manukau Harbour;
biota, vegetation associations; naturalised plants;
erosion.
- Id:
- 34812
- Submitter:
- zdenek
- Post_time:
- Monday, 05 December 2022 09:09