title: An optimization model of a New Zealand dairy farm

authors: Doole, Graeme J.

subjects: dairy system

abstract: Optimization models are a key tool for the analysis of emerging policies, prices, and technologies within grazing systems. A detailed, nonlinear optimization model of a New Zealand dairy farming system is described. This framework is notable for its inclusion of pasture residual mass, pasture utilization, and intake regulation as key management decisions. Validation of the model shows that the detailed representation of key biophysical relationships in the model provides an enhanced capacity to provide reasonable predictions outside of calibrated scenarios. Moreover, the flexibility of management plans in the model enhances its stability when faced with significant perturbations. In contrast, the inherent rigidity present in a less-detailed linear programming model is shown to limit its capacity to provide reasonable predictions away from the calibrated baseline. A sample application also demonstrates how the model can be used to identify pragmatic strategies to reduce greenhouse gas emissions.

text: An optimization model of a New Zealand dairy farm Optimization models are a key tool for the analysis of emerging policies, prices, and technologies within grazing systems. A detailed, nonlinear optimization model of a New Zealand dairy farming system is described. This framework is notable for its inclusion of pasture residual mass, pasture utilization, and intake regulation as key management decisions. Validation of the model shows that the detailed representation of key biophysical relationships in the model provides an enhanced capacity to provide reasonable predictions outside of calibrated scenarios. Moreover, the flexibility of management plans in the model enhances its stability when faced with significant perturbations. In contrast, the inherent rigidity present in a less-detailed linear programming model is shown to limit its capacity to provide reasonable predictions away from the calibrated baseline. A sample application also demonstrates how the model can be used to identify pragmatic strategies to reduce greenhouse gas emissions.

year: 2013

title: Peat humification records from Restionaceae bogs in northern New Zealand as potential indicators of Holocene precipitation, seasonality, and ENSO

authors: Newnham, Rewi M.

subjects: Science & Technology

abstract: In comparison with temperature reconstructions, New Zealand proxy records for paleo-precipitation are rare, despite the importance of precipitation in contemporary climate variability and for projected climate impacts. In this study, records of mid-late Holocene palaeomoisture variation were derived for two hydrologically separate ombrotrophic Restionaceae bogs in northern New Zealand, based on peat humification analysis. At each site, three cores were analysed for peat humification, facilitating both intra- and inter-site comparisons. Age models for the six sequences were developed using radiocarbon dating and tephrochronology. Twelve tephras (including six cryptotephras) were recognised, four of which were used to precisely link the two sites and to define start and end points for the records at 7027 ± 170 (Tuhua tephra) and 1718 ± 10 cal yr BP (Taupo tephra) (2σ-age ranges), respectively. We find individual differences between the six peat humification records at short-term timescales that are presumably due to local site factors, in particular changing vegetation and microtopography, or to changes in the composition of the material analysed. Stronger longer-term coherence is observed between all six records but is attributed to slow anaerobic decay over time because the implied trend towards wetter summers in the late Holocene cannot be corroborated by independent climate proxies. Despite these confounding factors, centennial scale shifts in bog surface wetness are a pervasive feature of all six records with varying degrees of overlap in time that show strong correspondence with El Niño-Southern Oscillation reconstructions from the eastern equatorial Pacific. These results indicate the potential for peat humification records from New Zealand's ombrotrophic bogs to elucidate past climate variability and also demonstrate the importance of developing multiple well-dated profiles from more than one site.

text: Peat humification records from Restionaceae bogs in northern New Zealand as potential indicators of Holocene precipitation, seasonality, and ENSO In comparison with temperature reconstructions, New Zealand proxy records for paleo-precipitation are rare, despite the importance of precipitation in contemporary climate variability and for projected climate impacts. In this study, records of mid-late Holocene palaeomoisture variation were derived for two hydrologically separate ombrotrophic Restionaceae bogs in northern New Zealand, based on peat humification analysis. At each site, three cores were analysed for peat humification, facilitating both intra- and inter-site comparisons. Age models for the six sequences were developed using radiocarbon dating and tephrochronology. Twelve tephras (including six cryptotephras) were recognised, four of which were used to precisely link the two sites and to define start and end points for the records at 7027 ± 170 (Tuhua tephra) and 1718 ± 10 cal yr BP (Taupo tephra) (2σ-age ranges), respectively. We find individual differences between the six peat humification records at short-term timescales that are presumably due to local site factors, in particular changing vegetation and microtopography, or to changes in the composition of the material analysed. Stronger longer-term coherence is observed between all six records but is attributed to slow anaerobic decay over time because the implied trend towards wetter summers in the late Holocene cannot be corroborated by independent climate proxies. Despite these confounding factors, centennial scale shifts in bog surface wetness are a pervasive feature of all six records with varying degrees of overlap in time that show strong correspondence with El Niño-Southern Oscillation reconstructions from the eastern equatorial Pacific. These results indicate the potential for peat humification records from New Zealand's ombrotrophic bogs to elucidate past climate variability and also demonstrate the importance of developing multiple well-dated profiles from more than one site.

year: 2019

title: Akuhata Mokena: Eldest son of Mokena Hou

authors: Hart, Philip

abstract: Akuhata Mokena was recorded as being the first child of Mokena Hou and Rina. By the early 1860s he was living at the northern boundary of the Aroha Block as well as at Puriri, where he dug kauri gum. From 1857 to 1868 he also cultivated close to the southern edge of the future Thames township. Having run cattle on the Aroha block from 1867 onwards, he settled there in 1878, operating the first hotel to be erected at the hot springs. 
In the land court he tried to obtain interests in as many land blocks as possible, and obtained income by selling some of these. After a brief involvement in Te Aroha mining, when he was the only member of his family to delay ceding their land for mining, he returned to live at Puriri. He also invested, very modestly, in mining at Thames and Puriri. 
A rangatira who was steadfastly loyal to the Crownt, when he died without issue his estate became a cause of conflict between Maori and Pakeha perceptions of how it should be shared amongst his wife and his family.

text: Akuhata Mokena: Eldest son of Mokena Hou Akuhata Mokena was recorded as being the first child of Mokena Hou and Rina. By the early 1860s he was living at the northern boundary of the Aroha Block as well as at Puriri, where he dug kauri gum. From 1857 to 1868 he also cultivated close to the southern edge of the future Thames township. Having run cattle on the Aroha block from 1867 onwards, he settled there in 1878, operating the first hotel to be erected at the hot springs. 
In the land court he tried to obtain interests in as many land blocks as possible, and obtained income by selling some of these. After a brief involvement in Te Aroha mining, when he was the only member of his family to delay ceding their land for mining, he returned to live at Puriri. He also invested, very modestly, in mining at Thames and Puriri. 
A rangatira who was steadfastly loyal to the Crownt, when he died without issue his estate became a cause of conflict between Maori and Pakeha perceptions of how it should be shared amongst his wife and his family.

year: 2016