title: Fluxes of carbon dioxide and water vapour at a Waikato peat bog

authors: Smith, Jeff

abstract: New Zealand wetlands are threatened entities and the remaining 15% of pre-European freshwater wetlands are important refuges for plant and animal species, while also providing historical information on past environmental changes. Hydrological regimes ultimately determine wetland ecosystem structure and function, with peat accumulation believed to be promoted by a high water table that minimises aerobic decomposition of peat. The carbon budget is relevant to the successional development of wetlands, as feedback relationships occur between vegetation, soils, hydrology and bog formation. Research on carbon transfer provides knowledge of bog development, along with information for managing wetland resources.

Moanatuatua Scientific Reserve is a 114 ha remnant of a raised peat bog located 18 km southeast of Hamilton. Drainage of surrounding agricultural land is believed to have lowered the water table at the remnant bog, with peat degradation occurring as a consequence. The aim of this research was to investigate fluxes of carbon dioxide and water vapour at Moanatuatua Scientific Reserve to identify controls of carbon sequestration and determine whether a lowered water table has led to net carbon loss. This knowledge will provide more accurate information for long-term management of raised peat bogs in the Waikato.

A closed-path eddy covariance system was used to measure half-hourly fluxes of CO₂ and water vapour at Moanatuatua between 15 December 1998 and 15 December 2000. Meteorological data and water table elevation were also monitored at half-hourly intervals. A portable chamber system was used to measure fluxes of CO₂ from the peat substrate during field visits.

The present precipitation regime is dominated by low magnitude, high frequency events and this ensures that moisture is generally available in the plant canopy so that 64% of precipitation was removed as evaporation. While the dense plant canopy restricts evaporation from the moist peat surface, plant physiological regulation of transpiration is relatively less important and λЕ is controlled more by availability of radiation than by stomatal controls observed over short periods during summer by previous researchers.

At the diurnal scale, carbon uptake is greatest during summer mornings. The bog was a sink of carbon for almost all of 1999 and 2000, apart from 2-3 months during winter when the wetland was a source of CO₂. Annual sequestration of carbon was 1.85 and 2.10 tCha⁻¹ for 1999 and 2000 respectively: greater than observations at other wetlands around the world. Ecosystem respiration is driven by temperature and GEP was modelled from inputs of PPFD. Reduced magnitude of solar radiation under increasingly cloudy conditions caused by climate change scenarios will have negligible effect on carbon sequestration due to improved radiation use efficiency under these conditions. Compared with annual sequestration for 1999, the magnitude of annual NEP was not reduced in 2000 despite a deeper water table during the latter year. Photosynthetic production may be stimulated by a deeper water table, which would offset increased respiration losses under these conditions. This is encouraging for the sustainability of the wetland habitat, however further research is required to test the hypothesis that sequestered carbon is being stored as peat and not as aboveground biomass.

text: Fluxes of carbon dioxide and water vapour at a Waikato peat bog New Zealand wetlands are threatened entities and the remaining 15% of pre-European freshwater wetlands are important refuges for plant and animal species, while also providing historical information on past environmental changes. Hydrological regimes ultimately determine wetland ecosystem structure and function, with peat accumulation believed to be promoted by a high water table that minimises aerobic decomposition of peat. The carbon budget is relevant to the successional development of wetlands, as feedback relationships occur between vegetation, soils, hydrology and bog formation. Research on carbon transfer provides knowledge of bog development, along with information for managing wetland resources.

Moanatuatua Scientific Reserve is a 114 ha remnant of a raised peat bog located 18 km southeast of Hamilton. Drainage of surrounding agricultural land is believed to have lowered the water table at the remnant bog, with peat degradation occurring as a consequence. The aim of this research was to investigate fluxes of carbon dioxide and water vapour at Moanatuatua Scientific Reserve to identify controls of carbon sequestration and determine whether a lowered water table has led to net carbon loss. This knowledge will provide more accurate information for long-term management of raised peat bogs in the Waikato.

A closed-path eddy covariance system was used to measure half-hourly fluxes of CO₂ and water vapour at Moanatuatua between 15 December 1998 and 15 December 2000. Meteorological data and water table elevation were also monitored at half-hourly intervals. A portable chamber system was used to measure fluxes of CO₂ from the peat substrate during field visits.

The present precipitation regime is dominated by low magnitude, high frequency events and this ensures that moisture is generally available in the plant canopy so that 64% of precipitation was removed as evaporation. While the dense plant canopy restricts evaporation from the moist peat surface, plant physiological regulation of transpiration is relatively less important and λЕ is controlled more by availability of radiation than by stomatal controls observed over short periods during summer by previous researchers.

At the diurnal scale, carbon uptake is greatest during summer mornings. The bog was a sink of carbon for almost all of 1999 and 2000, apart from 2-3 months during winter when the wetland was a source of CO₂. Annual sequestration of carbon was 1.85 and 2.10 tCha⁻¹ for 1999 and 2000 respectively: greater than observations at other wetlands around the world. Ecosystem respiration is driven by temperature and GEP was modelled from inputs of PPFD. Reduced magnitude of solar radiation under increasingly cloudy conditions caused by climate change scenarios will have negligible effect on carbon sequestration due to improved radiation use efficiency under these conditions. Compared with annual sequestration for 1999, the magnitude of annual NEP was not reduced in 2000 despite a deeper water table during the latter year. Photosynthetic production may be stimulated by a deeper water table, which would offset increased respiration losses under these conditions. This is encouraging for the sustainability of the wetland habitat, however further research is required to test the hypothesis that sequestered carbon is being stored as peat and not as aboveground biomass.

year: 2003

title: The early Pliocene Titiokura Formation: stratigraphy of a thick, mixed carbonate-siliciclastic shelf succession in Hawke's Bay Basin, New Zealand

authors: Bland, Kyle J.

subjects: Pliocene

abstract: This paper presents a systematic stratigraphic description of the architecture of the early Pliocene Titiokura Formation (emended) in the Te Waka and Maungaharuru Ranges of western Hawke's Bay, and presents a facies, sequence stratigraphic, and paleoenvironmental analysis of the sedimentary succession. The Titiokura Formation is of early Pliocene (Opoitian-Waipipian) age, and unconformably overlies Mokonui Formation, which is a regressive late Miocene and early Pliocene (Kapitean to early Opoitian) succession. In the Te Waka Range and the southern parts of the Maungaharuru Range, the Titiokura Formation comprises a single limestone sheet 20-50 m thick, with calcareous sandstone parts. In the vicinity of Taraponui Trig, and to the northeast, the results of 1:50 000 mapping show that the limestone gradually partitions into five members, which thicken markedly to the northeast to total thicknesses of c. 730 m, and concomitantly become dominated by siliciclastic sandstone. The members (all new) from lower to upper are: Naumai Member, Te Rangi Member, Taraponui Member, Bellbird Bush Member, and Opouahi Member. The lower four members are inferred to each comprise an obliquity-controlled 41 000 yr 6th order sequence, and the Opouahi Member at least two such sequences. The sequences typically have the following architectural elements from bottom to top: disconformable sequence boundary that formed as a transgressive surface of erosion; thin transgressive systems tracts (TSTs) with onlap and backlap shellbeds, or alternatively, a single compound shellbed; downlap surface; and very thick (70-200 m) highstand (HST) and regressive systems tracts (RST) composed of fine sandstone. The sequences in the Opouahi Member have cryptic TSTs, sandy siltstone to silty sandstone HSTs, and cross-bedded, differentially cemented, fine sandstone RSTs; a separate variant is an 11 m thick bioclastic limestone (grainstone and packstone) at the top of the member that crops out in the vicinity of Lake Opouahi. Lithostratigraphic correlations along the crest of the ranges suggest that the Titiokura Formation, and its correlatives to the south around Puketitiri, represent a shoreline-to-shelf linked depositional system. Carbonate production was focused around a rocky seascape as the system onlapped basement in the south, with dispersal and deposition of the comminuted carbonate on an inner shelf to the north, which was devoid of siliciclastic sediment input. The rates of both subsidence and siliciclastic sediment flux increased rapidly to the northeast of the carbonate "platform", with active progradation and offlap of the depositional system into more axial parts of Hawke's Bay Basin.

text: The early Pliocene Titiokura Formation: stratigraphy of a thick, mixed carbonate-siliciclastic shelf succession in Hawke's Bay Basin, New Zealand This paper presents a systematic stratigraphic description of the architecture of the early Pliocene Titiokura Formation (emended) in the Te Waka and Maungaharuru Ranges of western Hawke's Bay, and presents a facies, sequence stratigraphic, and paleoenvironmental analysis of the sedimentary succession. The Titiokura Formation is of early Pliocene (Opoitian-Waipipian) age, and unconformably overlies Mokonui Formation, which is a regressive late Miocene and early Pliocene (Kapitean to early Opoitian) succession. In the Te Waka Range and the southern parts of the Maungaharuru Range, the Titiokura Formation comprises a single limestone sheet 20-50 m thick, with calcareous sandstone parts. In the vicinity of Taraponui Trig, and to the northeast, the results of 1:50 000 mapping show that the limestone gradually partitions into five members, which thicken markedly to the northeast to total thicknesses of c. 730 m, and concomitantly become dominated by siliciclastic sandstone. The members (all new) from lower to upper are: Naumai Member, Te Rangi Member, Taraponui Member, Bellbird Bush Member, and Opouahi Member. The lower four members are inferred to each comprise an obliquity-controlled 41 000 yr 6th order sequence, and the Opouahi Member at least two such sequences. The sequences typically have the following architectural elements from bottom to top: disconformable sequence boundary that formed as a transgressive surface of erosion; thin transgressive systems tracts (TSTs) with onlap and backlap shellbeds, or alternatively, a single compound shellbed; downlap surface; and very thick (70-200 m) highstand (HST) and regressive systems tracts (RST) composed of fine sandstone. The sequences in the Opouahi Member have cryptic TSTs, sandy siltstone to silty sandstone HSTs, and cross-bedded, differentially cemented, fine sandstone RSTs; a separate variant is an 11 m thick bioclastic limestone (grainstone and packstone) at the top of the member that crops out in the vicinity of Lake Opouahi. Lithostratigraphic correlations along the crest of the ranges suggest that the Titiokura Formation, and its correlatives to the south around Puketitiri, represent a shoreline-to-shelf linked depositional system. Carbonate production was focused around a rocky seascape as the system onlapped basement in the south, with dispersal and deposition of the comminuted carbonate on an inner shelf to the north, which was devoid of siliciclastic sediment input. The rates of both subsidence and siliciclastic sediment flux increased rapidly to the northeast of the carbonate "platform", with active progradation and offlap of the depositional system into more axial parts of Hawke's Bay Basin.

year: 2004-12-01

title: Mā ngā huruhuru ka rere te manu: Understanding leadership for critical educational reform in Aotearoa New Zealand

authors: Anderson, Zac Kylie Elizabeth

subjects: educational leadership

abstract: The research project presented in this thesis explores the leadership journeys of four first-time principals engaging in Kia Eke Panuku, a professional development initiative in English-medium secondary schools in Aotearoa New Zealand.  It seeks to understand the role these first-time principals play in insitutionalising to depth, educational reform to enable Māori students to pursue their potential as Māori under the Ka Hikitia imperative.  This thesis investigates the type of leadership required to achieve educational reform for Māori learners in Aotearoa, embedded in the inherent promise of the Treaty of Waitangi.
  
This thesis contends these principals contribute to educational reform by bringing criticality to their leadership and embracing an ongoing and iterative process of conscientisation and resistance, leading to transformative praxis.  These principals recognised their role as educators leading pedagogical change in their schools, as well as leading others within their sphere of influence to ultimately change the fabric of society in Aotearoa.  They both learned and led alongside each other, displaying an openness to embracing multiple worldviews with a deeply held moral imperative to eradicate oppression of Māori students.  Such a stance actively creates bicultural spaces within schools, where both Treaty partners can benefit from the principles of the Treaty promises.

text: Mā ngā huruhuru ka rere te manu: Understanding leadership for critical educational reform in Aotearoa New Zealand The research project presented in this thesis explores the leadership journeys of four first-time principals engaging in Kia Eke Panuku, a professional development initiative in English-medium secondary schools in Aotearoa New Zealand.  It seeks to understand the role these first-time principals play in insitutionalising to depth, educational reform to enable Māori students to pursue their potential as Māori under the Ka Hikitia imperative.  This thesis investigates the type of leadership required to achieve educational reform for Māori learners in Aotearoa, embedded in the inherent promise of the Treaty of Waitangi.
  
This thesis contends these principals contribute to educational reform by bringing criticality to their leadership and embracing an ongoing and iterative process of conscientisation and resistance, leading to transformative praxis.  These principals recognised their role as educators leading pedagogical change in their schools, as well as leading others within their sphere of influence to ultimately change the fabric of society in Aotearoa.  They both learned and led alongside each other, displaying an openness to embracing multiple worldviews with a deeply held moral imperative to eradicate oppression of Māori students.  Such a stance actively creates bicultural spaces within schools, where both Treaty partners can benefit from the principles of the Treaty promises.

year: 2018