The Waimakariri River once flowed through Christchurch, forming an area that is rich in deep alluvial soils with interspersed peaty soils and coastal sands. These diverse soil types once supported a variety of ecosystems including impressive podocarp forests, and abundant freshwater springs which formed the various low gradient streams and extensive wetland networks.
Impressive podocarp forest once covered the bulk of the plains, following extensive deforestation for farming and industrial development, Deans/Riccarton Bush is one of the only significant examples of a remnant kahikatea-ribbonwood forest.
The younger alluvial soils and coastal dune systems produced extensive shrubland and grassland communities. These areas had hardy species adapted to survival in very well-drained soils. Some regionally rare species are Olearia adenocarpa adenocarpa, dryland button daisy (Leptinella serrulata) and the coastal dune stabiliser, pingao. The West Melton savannahs (PDF 1.37 MB) and the New Brighton dunes represent some great examples of these habitats.
Springs and streams
The abundant freshwater springs throughout the zone support a network of low gradient streams and rivers including the Avon/Ōtākaro, Heathcote/Ōpāwaho, Styx/Pūrākaunui and Ōtūkaikino and catchments. The Ōtūkaikino catchment supports a wide range of introduced and native aquatic life and has great restoration potential.
The Cashmere Stream (which feeds the Heathcote River/Ōpāwaho) has also been identified as a high value ecological system and is one of few still suitable for supporting sensitive and rare species such as koura, kakahi and blue-gill bullies.
A number of peaty wetlands occur in historic back swamp areas including Travis Wetland and the Sanctuary wetlands, which is the largest wetland area on the lower Waimakariri River. The wetlands contain some fascinating cryptic species including the marsh crake and Australasian bittern. Productive estuarine and lagoon habitats are home to a diverse array of waders and migratory birds. The Avon-Heathcote Estuary/Ihutai and Brooklands lagoon are the two largest examples of these habitats within the zone.