Aeolian sand transport Journal Paper
- Sarre, R.
- Journal / Source
- Progress in Physical Geography
- Wairarapa Plains Ecological District (117 633 ha) lies in the southern North Island between the Rimutaka and Tararua Ranges to the west, and the eastern Wairarapa hills and Aorangi Ranges to the east. The southern coastal boundary of the Ecological District is at Palliser Bay and the northern boundary is where the Ruamahanga River emerges from hill country near Mount Bruce. The Ecological District is primarily a sedimentary basin produced by marine and alluvial deposition, but also contains localised low hills. Lake Wairarapa and the smaller Lake Onoke are distinctive features; their shorelines retain some of the extensive wetlands that previously dominated the Ecological District. People have inhabited the Ecological District for many centuries. Prior to human settlement, podocarp-dominant forest covered most of the Ecological District. Maori fires in the seventeenth century destroyed most original podocarp forest. Native grasslands, fernland, swamps and scrub then replaced the forests. Arrival of Europeans in the mid-nineteenth century brought further change to indigenous ecosystems. Much of the remaining forest was removed, smaller wetlands were drained, and native fernland and scrub cleared. Indigenous ecosystems have now largely been replaced with exotic pasture and tree shelter-belts. More recently, diversion and barrage construction on the Ruamahanga River has halted the frequent widespread flooding which maintained the extensive wetlands of the southern plains, most of which have now also been drained. A survey was carried out to document the remaining natural areas in the Wairarapa Plains Ecological District to provide a basis for planning for their protection. The following approach was used for that survey. The Ecological District was subdivided into two bioclimatic zones: coastal (extending inland for approximately 1 km); and semi-coastal - lowland (the remainder of the Ecological District). The Ecological District was also divided into 14 land types, based on landform and underlying geology. Those land types were used, in conjunction with bioclimatic zones and information on vegetation type, to classify study areas into comparable ecological units. That framework of ecological units was used in combination with a set of standard criteria to select Recommended Areas for Protection. The criteria were: present versus past extent, landscape and ecological diversity, naturalness, size, shape of area, surrounding landscape, fragility and threat, ecological viability and long-term sustainability, and representativeness. Other factors taken into account included species distribution limits, rarity and endemism (of flora and fauna), and the values contained within existing protected areas. Areas of indigenous vegetation in the district were mapped and described in a draft reconnaissance report. Subsequently this ecological information was examined to assess the relative value of the natural areas identified. These natural areas were then assigned to one of five categories: Recommended Area for Protection (RAP); areas of High and Moderate-High and moderate biological importance (that did not qualify as RAP); or none of the above. Field surveys of potential RAPs (i.e. the highest priority for protection) was then undertaken. Nineteen Recommended Areas for Protection were identified and are described in this report. They cover approximately 1250 ha (1.1%) of the Wairarapa Plains Ecological District and vi include examples of remnant primary forest, secondary forest, scrub and shrubland, and wetland communities (both freshwater and estuarine). The RAPs are the highest priorities for protection because they are the largest or best examples of inadequately protected indigenous vegetation in the district. In addition, 182 natural areas were identified and ranked, in terms of their biological importance, into three categories: High, Medium or Low. While not necessarily the best or largest examples of their ecological association or ecological unit in the district, these sites were nevertheless considered to be significant areas of indigenous vegetation or wildlife habitats. Their protection would enhance the Ecological District's network of protected natural areas and provide opportunities for ecological restoration. If protection is not possible for RAP's then the relative priority for protection of those other sites will increase.
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