title: Understanding the role and impact of introduced honey bees in a submontane indigenous forest ecosystem

authors: Nepia, Rachel E.

subjects: pollination

abstract: New Zealand’s apiculture industry is the fastest growing in the world, expanding in agricultural landscapes, as well as in native ecosystems. While this has obvious benefits for economy and industry, the impacts on sustainability of native ecosystems are less easy to discern. Honey bees (Apis mellifera) have a suite of potential impacts, both positive and negative, on native plants and flower visitors in native ecosystems. This research aimed to investigate the impact of managed introductions of Apis mellifera in native forest dominated by Weinmannia racemosa and Ixerba brexioides, two native forest trees used extensively for monofloral honey production in New Zealand. Research focused on three key areas: 1) timing and availability of floral nectar resources; 2) impacts on plants, particularly I. brexioides and W. racemosa; and 3) impacts on invertebrate flower visitor communities. 
Availability of floral nectar resources from I. brexioides and W. racemosa was assessed using a combination of nectar collection and phenology data. Pollination potential of honey bees was assessed using video surveillance and effects on seed set of I. brexioides and W. racemosa were observed using exclusion experiments. Community-level effects on invertebrate flower visitors were assessed using collection of flower visitors and assessment of community data using multivariate and other statistical approaches.
Timing and availability of floral nectar resource showed extreme variation between annual cycles. Nectar sugar production was lowest during a hot, dry summer compared with a cooler, wetter summer, in terms of both sugar production per flower and flower production per tree. At a landscape scale, this can have serious flow-on effects for foraging nectar-feeders, and hence for seed set of flowering plants.
Video surveillance showed that suitability of different flower visitors for pollination of I. brexioides and W. racemosa differed. For W. racemosa all groups of flower visitors contacted reproductive structures, allowing for successful pollination. However for I. brexioides, pollination potential was greatest for birds, beetles and native bees and least for spiders, wasps, ants and honey bees. Seed set for I. brexioides was highest at pest-proof fenced sites and lowest at high hive density sites, whereas W. racemosa seed set was highest at high hive density sites, and lowest at low density sites. Weinmannia racemosa had lowest levels of pollen limitation at sites of high hive density. The combination of W. racemosa responses at the high hive density site suggest that small-flowered species, such as W. racemosa, have the potential to benefit from increased pollination success in areas where honey bees are frequent visitors.
Community analysis showed differences in flower visitor communities between sites with high and low honey bee hive density. Honey bees were the key species contributing to differences between high and low hive density sites. Diversity of insect flower visitors was higher at low hive density sites. Network analysis highlighted structural differences in networks between high and low hive density sites in terms of connectance, nestedness, and species-level indices. High and low hive density sites had a similar number of species that were native and non-native, but high hive density sites had more frequent interactions with non-natives, and 45 % of those interactions were from honey bees.
Pilot studies investigating methods for studying plant-pollinator interactions highlighted a need to tailor methods of pollen isolation to fit the research question, i.e. whether research is focused on pollination interactions or diet-related questions. Comparison of methods for understanding plant-pollinator interactions concluded that identification of pollen by microscopic means identified a greater breadth of plant-pollinator interactions than that identified by field observations alone. However, DNA-based methods of pollen identification have the potential for even greater specificity, cost-effectiveness, and answering a range of questions not possible with traditional methods. 
Analysis and findings from this research support a case indicating that honey bees can affect seed set of native plants, and communities of invertebrate flower visitors in a number of ways. Prevention of permanent changes to flower visitor communities should be prioritised by preserving large areas of intact native forest where low levels of fragmentation create refuges for native flower visitors. Estimates of annual sugar production for I. brexioides and W. racemosa call attention to the need to build greater flexibility into legislated stocking rates in native forest, to minimise competitive effects on native flower visitors during low production years. Developing these measures will build sustainability into New Zealand models of apicultural practise, ensuring longevity of honey operations and protection of native ecosystems.

text: Understanding the role and impact of introduced honey bees in a submontane indigenous forest ecosystem New Zealand’s apiculture industry is the fastest growing in the world, expanding in agricultural landscapes, as well as in native ecosystems. While this has obvious benefits for economy and industry, the impacts on sustainability of native ecosystems are less easy to discern. Honey bees (Apis mellifera) have a suite of potential impacts, both positive and negative, on native plants and flower visitors in native ecosystems. This research aimed to investigate the impact of managed introductions of Apis mellifera in native forest dominated by Weinmannia racemosa and Ixerba brexioides, two native forest trees used extensively for monofloral honey production in New Zealand. Research focused on three key areas: 1) timing and availability of floral nectar resources; 2) impacts on plants, particularly I. brexioides and W. racemosa; and 3) impacts on invertebrate flower visitor communities. 
Availability of floral nectar resources from I. brexioides and W. racemosa was assessed using a combination of nectar collection and phenology data. Pollination potential of honey bees was assessed using video surveillance and effects on seed set of I. brexioides and W. racemosa were observed using exclusion experiments. Community-level effects on invertebrate flower visitors were assessed using collection of flower visitors and assessment of community data using multivariate and other statistical approaches.
Timing and availability of floral nectar resource showed extreme variation between annual cycles. Nectar sugar production was lowest during a hot, dry summer compared with a cooler, wetter summer, in terms of both sugar production per flower and flower production per tree. At a landscape scale, this can have serious flow-on effects for foraging nectar-feeders, and hence for seed set of flowering plants.
Video surveillance showed that suitability of different flower visitors for pollination of I. brexioides and W. racemosa differed. For W. racemosa all groups of flower visitors contacted reproductive structures, allowing for successful pollination. However for I. brexioides, pollination potential was greatest for birds, beetles and native bees and least for spiders, wasps, ants and honey bees. Seed set for I. brexioides was highest at pest-proof fenced sites and lowest at high hive density sites, whereas W. racemosa seed set was highest at high hive density sites, and lowest at low density sites. Weinmannia racemosa had lowest levels of pollen limitation at sites of high hive density. The combination of W. racemosa responses at the high hive density site suggest that small-flowered species, such as W. racemosa, have the potential to benefit from increased pollination success in areas where honey bees are frequent visitors.
Community analysis showed differences in flower visitor communities between sites with high and low honey bee hive density. Honey bees were the key species contributing to differences between high and low hive density sites. Diversity of insect flower visitors was higher at low hive density sites. Network analysis highlighted structural differences in networks between high and low hive density sites in terms of connectance, nestedness, and species-level indices. High and low hive density sites had a similar number of species that were native and non-native, but high hive density sites had more frequent interactions with non-natives, and 45 % of those interactions were from honey bees.
Pilot studies investigating methods for studying plant-pollinator interactions highlighted a need to tailor methods of pollen isolation to fit the research question, i.e. whether research is focused on pollination interactions or diet-related questions. Comparison of methods for understanding plant-pollinator interactions concluded that identification of pollen by microscopic means identified a greater breadth of plant-pollinator interactions than that identified by field observations alone. However, DNA-based methods of pollen identification have the potential for even greater specificity, cost-effectiveness, and answering a range of questions not possible with traditional methods. 
Analysis and findings from this research support a case indicating that honey bees can affect seed set of native plants, and communities of invertebrate flower visitors in a number of ways. Prevention of permanent changes to flower visitor communities should be prioritised by preserving large areas of intact native forest where low levels of fragmentation create refuges for native flower visitors. Estimates of annual sugar production for I. brexioides and W. racemosa call attention to the need to build greater flexibility into legislated stocking rates in native forest, to minimise competitive effects on native flower visitors during low production years. Developing these measures will build sustainability into New Zealand models of apicultural practise, ensuring longevity of honey operations and protection of native ecosystems.

year: 2020

title: Development and application of a method for U-Th dating of the Bonney Drift, Taylor Valley, Antarctica

authors: Smith, David W.

abstract: The lacustrine carbonates of the Bonney Drift, Taylor Valley, Antarctica were deposited in lakes proglacial to glaciers advancing through the valley, and now occur as lag and clasts in the glacial drift formed by the glacier. They commonly contain 8 to 25% detritus, including high levels of silica, titanium, iron, manganese, and other elements; making the extraction and purification of uranium and thorium problematic.

A standard U-Th dating process was adapted to deal with the technical problems peculiar to the samples dated. Silica often formed a gel at the head of the U-Th separation column, and was removed using HF. Titanium frequently precipitated out during the conversion of the thorium fraction from a HCl matrix to HNO₃ form (used for further ion exchange purification) causing very low thorium recovery. This was overcome by using much higher volumes during conversion. 

The uranium eluate from the separation column often contained high levels of iron and manganese. These were removed on a small ion exchange column in HNO₃. The resin and wash volumes were adjusted to allow iron and manganese to wash off, but allowing the uranium to be held and eluted subsequently. 

An electrodeposition method was developed to achieve the thin plates necessary for alpha spectroscopy. Silver cathode discs were used in a teflon plating cell, with a stirrer rotating on the spiral planar platinum anode. An NH₄Cl/HCl electrolyte was used, adjusted in pH after sample uptake. 

Of the 62 samples successfully dated, 13 were eliminated for such reasons as low resolution and spectral shift; leaving 17 duplicates, one triplicate and 12 single analyses for further consideration. Samples with low ²³²Th/TIFFS
Th levels were corrected for detrital ²³²Th addition. 

The dates obtained were considered in terms of age, geographic distribution, and uranium isotope ratios and concentrations. δ180 suggested that samples were derived from either Taylor Glacier meltwaters, or possibly Ross Ice Sheet Stage 6 meltwaters, and showed that δ180 values in the meltwaters increased towards the middle of each event. 

Three major events were identified. 
(i) an extensive period of deposition around 240 to 300kA (Stage 9?), This may possibly represent two events, in a lake(s) most likely formed proglacial to an expanded Taylor Glacier. 
(ii) a short period of lacustrine conditions around 175 to 190 kA ago, correlated with either Taylor Glacier expansion at the end of Stage 7, or Ross Ice Sheet thickening at the start of Stage 6. 
(iii) a period of carbonate deposition from 130 to 80 kA( Stage 5), more extensive than that at 175-190 kA. The expanding glacier (Taylor II) then advanced through the carbonates, and those of the earlier events, and redeposited. 

The events interpreted appear to correlate with global interglacials, as suggested by Hendy et al (1979). It seems that during interglacials, the East Antarctic Ice Sheet expands (the absence of a sea ice apron allows increased precipitation). As a result, expansion of the East Antarctic Ice Sheet would be expected as a consequence of greenhouse gas warming, offsetting sea level rises caused by melting of temperate glaciers and ice sheets.

text: Development and application of a method for U-Th dating of the Bonney Drift, Taylor Valley, Antarctica The lacustrine carbonates of the Bonney Drift, Taylor Valley, Antarctica were deposited in lakes proglacial to glaciers advancing through the valley, and now occur as lag and clasts in the glacial drift formed by the glacier. They commonly contain 8 to 25% detritus, including high levels of silica, titanium, iron, manganese, and other elements; making the extraction and purification of uranium and thorium problematic.

A standard U-Th dating process was adapted to deal with the technical problems peculiar to the samples dated. Silica often formed a gel at the head of the U-Th separation column, and was removed using HF. Titanium frequently precipitated out during the conversion of the thorium fraction from a HCl matrix to HNO₃ form (used for further ion exchange purification) causing very low thorium recovery. This was overcome by using much higher volumes during conversion. 

The uranium eluate from the separation column often contained high levels of iron and manganese. These were removed on a small ion exchange column in HNO₃. The resin and wash volumes were adjusted to allow iron and manganese to wash off, but allowing the uranium to be held and eluted subsequently. 

An electrodeposition method was developed to achieve the thin plates necessary for alpha spectroscopy. Silver cathode discs were used in a teflon plating cell, with a stirrer rotating on the spiral planar platinum anode. An NH₄Cl/HCl electrolyte was used, adjusted in pH after sample uptake. 

Of the 62 samples successfully dated, 13 were eliminated for such reasons as low resolution and spectral shift; leaving 17 duplicates, one triplicate and 12 single analyses for further consideration. Samples with low ²³²Th/TIFFS
Th levels were corrected for detrital ²³²Th addition. 

The dates obtained were considered in terms of age, geographic distribution, and uranium isotope ratios and concentrations. δ180 suggested that samples were derived from either Taylor Glacier meltwaters, or possibly Ross Ice Sheet Stage 6 meltwaters, and showed that δ180 values in the meltwaters increased towards the middle of each event. 

Three major events were identified. 
(i) an extensive period of deposition around 240 to 300kA (Stage 9?), This may possibly represent two events, in a lake(s) most likely formed proglacial to an expanded Taylor Glacier. 
(ii) a short period of lacustrine conditions around 175 to 190 kA ago, correlated with either Taylor Glacier expansion at the end of Stage 7, or Ross Ice Sheet thickening at the start of Stage 6. 
(iii) a period of carbonate deposition from 130 to 80 kA( Stage 5), more extensive than that at 175-190 kA. The expanding glacier (Taylor II) then advanced through the carbonates, and those of the earlier events, and redeposited. 

The events interpreted appear to correlate with global interglacials, as suggested by Hendy et al (1979). It seems that during interglacials, the East Antarctic Ice Sheet expands (the absence of a sea ice apron allows increased precipitation). As a result, expansion of the East Antarctic Ice Sheet would be expected as a consequence of greenhouse gas warming, offsetting sea level rises caused by melting of temperate glaciers and ice sheets.

year: 1991

title: The Mātauranga Māori in Mathematics Directive: Exploring the place of mātauranga Māori in Mathematics teaching and learning

authors: Williams, Jessica Elizabeth

subjects: mathematics education

abstract: This thesis explores issues concerning mātauranga Māori in mathematics teaching and learning here in Aotearoa. The Ministry of Education has directed that mana ōrite mō te mātauranga Māori be embedded in teaching, learning, and assessment. Thus, this research primarily aims to understand the development leading to the directive of including mātauranga Māori in education policies. For the English-medium secondary education settings, the second and third aims of this research are to explore what mātauranga Māori means to teachers of mathematics and to consider the connections between mātauranga Māori and mathematics teaching and learning. To investigate these aims, a semi-structured group discussion with four secondary mathematics teachers from an English-medium setting was conducted. The results of this thesis highlight the confusion and challenges secondary mathematics educators have toward defining, and subsequently, implementing mātauranga Māori in their classrooms. This thesis also found that there is enthusiasm and interest around learning how to ensure indigenous and marginalised learners reach their mathematics potential. Believing that indigenous worldviews have the potential to shift education outcomes for minority learners, this thesis adds to literature related to indigenous education, secondary mathematics education, and English-medium education of Māori learners.

text: The Mātauranga Māori in Mathematics Directive: Exploring the place of mātauranga Māori in Mathematics teaching and learning This thesis explores issues concerning mātauranga Māori in mathematics teaching and learning here in Aotearoa. The Ministry of Education has directed that mana ōrite mō te mātauranga Māori be embedded in teaching, learning, and assessment. Thus, this research primarily aims to understand the development leading to the directive of including mātauranga Māori in education policies. For the English-medium secondary education settings, the second and third aims of this research are to explore what mātauranga Māori means to teachers of mathematics and to consider the connections between mātauranga Māori and mathematics teaching and learning. To investigate these aims, a semi-structured group discussion with four secondary mathematics teachers from an English-medium setting was conducted. The results of this thesis highlight the confusion and challenges secondary mathematics educators have toward defining, and subsequently, implementing mātauranga Māori in their classrooms. This thesis also found that there is enthusiasm and interest around learning how to ensure indigenous and marginalised learners reach their mathematics potential. Believing that indigenous worldviews have the potential to shift education outcomes for minority learners, this thesis adds to literature related to indigenous education, secondary mathematics education, and English-medium education of Māori learners.

year: 2023