title: Urban planning provides potential for lake restoration through catchment re-vegetation

authors: Duggan, Ian C.

subjects: Oligotrophication

abstract: Encroachment of urban areas into forest and farmland is typically considered to have detrimental effects on terrestrial and aquatic ecosystems. Most restoration strategies for lakes affected by urban development represent expensive short-term fixes requiring on-going management, with long-term restoration requiring external nutrient inputs (typically the major impact of urban development) to be significantly reduced. This study details, using a simple nutrient budget, the effects of the conversion of farmland to native forest in a lake catchment (Waiwhakareke/Horseshoe Lake in the Waiwhakareke Natural Heritage Park (WHNP), New Zealand) during urban encroachment. I show how far-sighted planning employed by management authorities can lead to urban growth being beneficial to aquatic systems. Even using this method, however, managers should not expect lakes to become immediately available as amenities. Although reduction in external nutrient loads brought about by the reforestation of lake catchments in urban areas will ultimately lead to phosphorus reduction and concomitant water quality improvements, such responses may take a number of years due a continued release of nutrients from bottom sediments if they are initially within rural catchments. Urban management authorities therefore need to possess a long-term outlook and commitment to such projects. Overall, the WHNP project acts as a model for future urban development and spread of cities, providing opportunities for the long-term restoration and conservation of lakes.

text: Urban planning provides potential for lake restoration through catchment re-vegetation Encroachment of urban areas into forest and farmland is typically considered to have detrimental effects on terrestrial and aquatic ecosystems. Most restoration strategies for lakes affected by urban development represent expensive short-term fixes requiring on-going management, with long-term restoration requiring external nutrient inputs (typically the major impact of urban development) to be significantly reduced. This study details, using a simple nutrient budget, the effects of the conversion of farmland to native forest in a lake catchment (Waiwhakareke/Horseshoe Lake in the Waiwhakareke Natural Heritage Park (WHNP), New Zealand) during urban encroachment. I show how far-sighted planning employed by management authorities can lead to urban growth being beneficial to aquatic systems. Even using this method, however, managers should not expect lakes to become immediately available as amenities. Although reduction in external nutrient loads brought about by the reforestation of lake catchments in urban areas will ultimately lead to phosphorus reduction and concomitant water quality improvements, such responses may take a number of years due a continued release of nutrients from bottom sediments if they are initially within rural catchments. Urban management authorities therefore need to possess a long-term outlook and commitment to such projects. Overall, the WHNP project acts as a model for future urban development and spread of cities, providing opportunities for the long-term restoration and conservation of lakes.

year: 2012

title: Volcanology of the Owharoa and Waikino ignimbrites, Waihi, Coromandel Volcanic Zone

authors: Julian, Hannah Alice

subjects: ignimbrites

abstract: The Waihi Caldera (Coromandel Volcanic Zone) is defined by a 15 km diameter gravity anomaly, which was active during the Pliocene and has been infilled by a 1.5 km-thick succession of volcanic deposits and lake sediments. The Owharoa and Waikino ignimbrites are both suspected to have been a product of the Waihi Caldera (Brathwaite & Christie, 1996). The aim of this study was to determine and compare the eruption and emplacement processes of the Owharoa and Waikino ignimbrites.
The ignimbrites were characterised in the field by facies analysis and dated by U-Pb zircon dating using laser ablation inductively coupled plasma mass spectrometry. Their petrographic characteristics were described by optical microscopy, scanning electron microscopy and X-ray powder diffraction. Geochemical characteristics were identified by electron microprobe analysis (on minerals and glass shards) and X-ray fluorescence spectrometry (on pumice and bulk ignimbrite).
The Owharoa Ignimbrite (3.76 ± 0.05 Ma, Vincent, 2012) is poorly sorted with variable degrees of welding degrees. Facies identified include pumice-rich and lithic-rich facies (O1), flattened pumice rich facies (O2), lithic rich, pumice poor facies (O3), dark grey, densely welded, fiamme rich facies (O4) and pumice rich facies (O5). Juvenile clasts include creamy rounded woody-textured pumice in the east, and dark to black, lensoidal, glassy fiamme in the west with quartz and plagioclase phenocrysts. Lithic clasts include volcanic lithics (rhyolite, andesite, and ignimbrite), and occasional sedimentary lithics (sandstone/siltstone).
The Waikino Ignimbrite (3.48 +/- 0.19 Ma) is a finer-grained, relatively well sorted, massive, glass shard matrix-rich (~93%) ignimbrite that is separated into two facies, W1, a softer, massive yellow basal facies; and W2 a grey, well welded, massive facies. The pumice within the Waikino Ignimbrite (1%) was no larger than coarse ash-sized, white fragments. The Waikino Ignimbrite had plagioclase, quartz, biotite (larger than the Owharoa Ignimbrite) and opaque minerals. Geochemically the Waikino Ignimbrite was rhyolitic with higher alkali content than the Owharoa Ignimbrite.
The Owharoa Ignimbrite represents the deposit of an intra-caldera, pulsating depositional pyroclastic flow that shows subtle variations in pumice and lithic abundance. The massive nature of the Waikino Ignimbrite indicates a consistent, steady pyroclastic flow, derived from an intensely fragmented magma to form a glass shard-rich, pumice-poor deposit. Both ignimbrites were sourced from the Waihi Caldera due to their proximity to the caldera, the lithic characteristics and their similar geochemistry and mineralogy. The closeness in age of the ignimbrites signifies the relationship between the deposits, and relationship they have with the Waihi Caldera. It is possible that the Waikino Ignimbrite was the last major eruption from the Waihi Caldera, therefore the end of the duration of the caldera can be identified as after the Waikino Ignimbrite eruption at 3.48 +/- 0.19 Ma.

text: Volcanology of the Owharoa and Waikino ignimbrites, Waihi, Coromandel Volcanic Zone The Waihi Caldera (Coromandel Volcanic Zone) is defined by a 15 km diameter gravity anomaly, which was active during the Pliocene and has been infilled by a 1.5 km-thick succession of volcanic deposits and lake sediments. The Owharoa and Waikino ignimbrites are both suspected to have been a product of the Waihi Caldera (Brathwaite & Christie, 1996). The aim of this study was to determine and compare the eruption and emplacement processes of the Owharoa and Waikino ignimbrites.
The ignimbrites were characterised in the field by facies analysis and dated by U-Pb zircon dating using laser ablation inductively coupled plasma mass spectrometry. Their petrographic characteristics were described by optical microscopy, scanning electron microscopy and X-ray powder diffraction. Geochemical characteristics were identified by electron microprobe analysis (on minerals and glass shards) and X-ray fluorescence spectrometry (on pumice and bulk ignimbrite).
The Owharoa Ignimbrite (3.76 ± 0.05 Ma, Vincent, 2012) is poorly sorted with variable degrees of welding degrees. Facies identified include pumice-rich and lithic-rich facies (O1), flattened pumice rich facies (O2), lithic rich, pumice poor facies (O3), dark grey, densely welded, fiamme rich facies (O4) and pumice rich facies (O5). Juvenile clasts include creamy rounded woody-textured pumice in the east, and dark to black, lensoidal, glassy fiamme in the west with quartz and plagioclase phenocrysts. Lithic clasts include volcanic lithics (rhyolite, andesite, and ignimbrite), and occasional sedimentary lithics (sandstone/siltstone).
The Waikino Ignimbrite (3.48 +/- 0.19 Ma) is a finer-grained, relatively well sorted, massive, glass shard matrix-rich (~93%) ignimbrite that is separated into two facies, W1, a softer, massive yellow basal facies; and W2 a grey, well welded, massive facies. The pumice within the Waikino Ignimbrite (1%) was no larger than coarse ash-sized, white fragments. The Waikino Ignimbrite had plagioclase, quartz, biotite (larger than the Owharoa Ignimbrite) and opaque minerals. Geochemically the Waikino Ignimbrite was rhyolitic with higher alkali content than the Owharoa Ignimbrite.
The Owharoa Ignimbrite represents the deposit of an intra-caldera, pulsating depositional pyroclastic flow that shows subtle variations in pumice and lithic abundance. The massive nature of the Waikino Ignimbrite indicates a consistent, steady pyroclastic flow, derived from an intensely fragmented magma to form a glass shard-rich, pumice-poor deposit. Both ignimbrites were sourced from the Waihi Caldera due to their proximity to the caldera, the lithic characteristics and their similar geochemistry and mineralogy. The closeness in age of the ignimbrites signifies the relationship between the deposits, and relationship they have with the Waihi Caldera. It is possible that the Waikino Ignimbrite was the last major eruption from the Waihi Caldera, therefore the end of the duration of the caldera can be identified as after the Waikino Ignimbrite eruption at 3.48 +/- 0.19 Ma.

year: 2016

title: On the stage Māori medium ITE: Listening to students’ voices

authors: Lee-Morgan, Jenny Bol Jun

subjects: Māori medium education

abstract: Māori-medium initial teacher education (ITE) is a small but highly important group ‘on stage’ in te ao Māori and New Zealand education. While education plays a major role in Māori language revitalisation, Māori language is also pivotal to Māori education if the aspiration ‘to live as Māori’ (Durie, 2001) is to be fulfilled. Māori-medium teachers are critical to the success of learners and their whānau who select a Māori-medium pathway and who can make a meaningful difference to the educational outcomes of Māori (Hōhepa, Hāwea, Tamatea, & Heaton, 2014). This article draws on the students’ voices in a two-year research project that centered on the development of a teaching and learning initiative within one Māori-medium ITE programme. Building on previous work by Hōhepa et al. (2014), this study adds another layer of students’ voices to understand more clearly language related issues and student experiences in Māori-medium ITE programmes. The article presents some of the complexities associated with Māori language regeneration facing students of Māori-medium ITE, with the understanding that whatever appears on the stage is always part of a greater narrative behind the scenes.

text: On the stage Māori medium ITE: Listening to students’ voices Māori-medium initial teacher education (ITE) is a small but highly important group ‘on stage’ in te ao Māori and New Zealand education. While education plays a major role in Māori language revitalisation, Māori language is also pivotal to Māori education if the aspiration ‘to live as Māori’ (Durie, 2001) is to be fulfilled. Māori-medium teachers are critical to the success of learners and their whānau who select a Māori-medium pathway and who can make a meaningful difference to the educational outcomes of Māori (Hōhepa, Hāwea, Tamatea, & Heaton, 2014). This article draws on the students’ voices in a two-year research project that centered on the development of a teaching and learning initiative within one Māori-medium ITE programme. Building on previous work by Hōhepa et al. (2014), this study adds another layer of students’ voices to understand more clearly language related issues and student experiences in Māori-medium ITE programmes. The article presents some of the complexities associated with Māori language regeneration facing students of Māori-medium ITE, with the understanding that whatever appears on the stage is always part of a greater narrative behind the scenes.

year: 2017