Journal Articles
Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915
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Item Are native shrubs a sustainable alternative to radiata pine on steep slopes? Insights using bioeconomic model for hill country farms in New Zealand(Taylor and Francis Group on behalf of the Royal Society of New Zealand, 2025-05-07) Wangui JC; Millner JP; Kenyon PR; Pain SJ; Tozer PRLimited data on native shrubs has hindered direct comparisons with pine radiata as afforestation options for steep slopes on New Zealand hill country sheep and beef farms. This study updated a native shrub sub-model (NSM) with new research data and developed a radiata pine sub-model (RPM) for integration into a bioeconomic model using STELLA Architect. The model assessed asynchronous afforestation of 10% of effective farm area with either option, comparing impacts on feed supply, sheep dynamics, and farm economics. NSM was updated with growth curve, foliage biomass, and carbon stock data from two New Zealand sites. RPM used literature for growth curve, carbon, and log production data. Simulations included a pasture-only (base) and afforestation with either species at 10% and 20% planting rates. Native shrubs reduced feed supply by 2.5% and 4.0%, while radiata pine reduced it by 7.0% and 7.4% at 10% and 20% planting rates. Reduced feed led to smaller flocks and lower cash flow. Radiata pine generated surplus through carbon and log income, offsetting reduced sheep flock cash flow, while native shrubs did not. Carbon prices of 64.2 and137.4 NZD/NZU would be needed for viability in the best- and worst-case scenarios. Native shrubs are potential land use option on steep slopes but require policy intervention to lower establishment costs and carbon prices.Item Nutritional composition of New Zealand native shrubs edible portions with fodder potential for ruminants(Taylor and Francis Group, 2024-11-13) Wangui JC; Pain SJ; Kenyon PR; Tozer PR; Simmonds G; Millner JPIn New Zealand, willow and poplar are used on hill farms for erosion control and to supplement pasture during low pasture periods. Some native shrubs are browsed by wild herbivores but remain unexplored for farmed ruminants. We evaluated the seasonal nutritional composition of five native New Zealand shrubs (Karamū, Pāpāuma, Karo, Whauwhaupaku, and Houhere) and compared them with willow (Kinuyanagi). Leaf and edible stem were analysed for nutritional composition and in vitro digestibility following AOAC procedures. Results showed that except Houhere, all other native shrubs leaves had lower crude protein (CP) (11 MJ/ kg DM) than Kinuyanagi. Kinuyanagi leaves were comparable to Houhere in ME and CP in spring but had lower CP in summer. Stem nutritional composition was similar across all shrubs. Acid and neutral detergent fibres in edible portions were comparable to those in common pastures, fodder crops, and forages in New Zealand. The findings suggest native shrubs could supplement low ME in summer pastures or winter herbage scarcity, but further research is needed on animal preference and intake.