What water sources and irrigation systems can be best utilized to continue regenerating the native flora at Pūtaringamotu Riccarton Bush?
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• Pūtaringamotu Riccarton Bush is a 7.8-hectare ngahere (forest) in Christchurch that is highly valued by the local community and hapu, Ngāi Tūāhuriri.
• The surrounding landscape has been drained due to urbanization and, in 1998, an irrigation system was installed to ensure survival of the forest. The Riccarton Bush Trust have asked us to investigate how this irrigation system may be improved.
• The research aimed to explore what water sources and irrigation systems could be best utilized to continue regenerating the native flora at Riccarton Bush. This involved determining whether variation in vegetation types and soil moisture across Riccarton Bush should be considered in the design of a new irrigation system.
• A literature review was conducted that focused on irrigation methods, native plant water needs, and the historical context of the site.
• Vegetation surveys at 13 field sites used a 5 x 5 m quadrat method to identify plant species and assess their abundance and maturity.
• Manual soil moisture samples were collected across 13 sites and analysis using ASTM DD2216 methods.
• TOMST TSM-4 soil moisture probes were calibrated and installed at field sites. These collected data over a month for analysis.
• A total of 32 plant species were identified, emphasizing both native species and the differences between mature plants and saplings.
• The relationship between soil moisture and vegetation was insufficient to draw any clear conclusions.
• The research indicates due to regeneration occurring and minimal changes in vegetation type compared to historical data, the current irrigation system appears sufficient to support continued regeneration of the forest.
• Research limitations included the limited number of field sites chosen and the inability to collect data year-round to account for seasonal soil moisture variations.
• Our recommendations for future research include updating the irrigation system with a focus on water conservation and incorporating supplementary water sources such as roof stormwater and potential spring water.