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Saline soil vegetation
Diagnostic features for identification in the field
For more information on identification of plants associated with saline habitats, click on appropriate photo:
![[atrbuc]](atrbuc.jpg) Atriplex buchananii
![[lepkir]](lepkir.jpg) Lepidium kirkii
Description of community and habitat
Saline soils in the driest Central Otago valleys occur mainly around the bases of hills where salt is being leached from weathered schist and Tertiary sediments, and in patches of alluvium in low parts of the landscape. Once quite extensive, they have been drastically reduced in area and modified by farming. Their survival is precarious. Instead of distinctive communities, there are haphazard assemblages of salt-tolerant plants which, with the exception of Lepidium kirkii (a rare, slender, annual), and Puccinellia raroflorens (salt grass) also grow on Otago coasts.
Saline areas with any natural characteristics that remain today are mostly small and fragmented. Cultivation and irrigation have replaced most such areas with exotic pasture. The remaining saltpans have managed to retain some of their native flora and fauna, although exotic flora is generally dominant.
Saline areas can often be identified by the presence of grey-white crust of salt on the surface of seemingly bare ground. On closer inspection, inconspicuous plants such as Atriplex buchananii can be seen. The vegetation immediately surrounding the most salty areas tends to be comprised of short grasses and herbs, including cushionfield.
Species present
Species which have been recorded on saline areas of the Maniototo Ecological District (from Patrick, 1989) [Note: an updated list can now be found in Rogers et al. 1999 Appendix 4 and iconic species list Table 3, p.8]:
(* denotes adventive species)
Crucerifae
Lepidium kirkii
Lepidium matau
Lepidium sisymbrioides
Chenopodiacae
*Chenopodium album
*Chenopodium erosum
Atriplex buchananii
*Atriplex rosea
Sarcocornia quinqueflora
Crassulaceae
Crassula multicaulis
Umbelliferae
Apium filiforme
Ranunculaceae
Myosurus minimus subsp. novae-zelandiae
Geraniacea
Geranium sessiliflorum
Caryophyllaceae
Colobanthus brevisepalus
Scleranthus uniflorus
Fabaceae
Carmichaelia compacta
Carmichaelia monroi
Carmichaelia petriei
Asteraceae
Vittadinia australis
*Vittadinia gracilis
Raoulia australis
Raoulia beauverdii
Cotula maniototo
Plantaginaceae
Plantago spathulata
*Plantago coronpus
Goodeniaceae
Selliera radicans
Primulaceae
Samolus repens
Scrophulariaceae
Limosella curdieana
Violaceae
Melicytus alpinus
Graminaceae
Puccinellia distans
Puccinellia stricta
Puccinellia fasiculata
Elymus rectisetus
Poa maniototo
*Hordeum jubatum
*Hordeum hystrix
Juncaginaceae
Triglochin palustre
Vegetation History
The Central Otago region has a complex history of disturbance. Post-glacial forest may never have extended to the drier basin of Central Otago, and the establishment of grassland, possibly through natural fires, preceded human settlement by several centuries (Wardle, 1985; McGlone, 1989; McGlone et al., 1995).
In the driest valleys of Central Otago, saltpans developed around the bases of hills where salt was leached from Tertiary sediments, and in valley floors subject to high water tables where salt in ground water accumulated in the soil. It appears that the saline soils were much more extensively distributed in the past than they are today (see Rogers et al. 1999). The presence and extent of the salty soils was a problem to farmers in the region.
Widespread irrigation and cultivation have replaced most saline soil areas with exotic pasture. The remaining areas are mostly small and fragmented, but do retain some of their native flora and fauna, adapted to these salty conditions. Exotic plants, however, generally dominate.
Information taken from:
Walker, S; Mark, A.F., and Bastow Wilson, J. 1995: The vegetation of Flat Top Hill: an area of semi-arid grassland/shrubland in Central Otago, New Zealand. NZ Journal of Ecology, 19(2): 175-194.
Grove, P. 1994: Maniototo Ecological District - a survey report for the Protected Natural Areas Programme, Dept of Conservation.
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