title: Evaluating 50 years of time-series soil radiocarbon data: Towards routine calculation of robust C residence times

authors: Baisden, W. Troy

subjects: ¹⁴C

abstract: In 1959, Athol Rafter began a substantial programme of monitoring the flow of ¹⁴C produced by atmospheric thermonuclear tests through New Zealand's atmosphere, biosphere and soil. By building on the original measurements through ongoing sampling, a database of over 500 soil radiocarbon measurements spanning 50 years has now been compiled. The datasets, including an 11-point time series, allow strong focus on the robust quantification of residence times ranging from years to decades. We describe key aspects of the dataset, including the ability to identify critical assumptions inherent in calculating soil C residence times. The 3 most critical assumptions relate to: (1) the proportion of old C ("fraction passive"), (2) the lag time between photosynthesis and C entering the modeled pool, and (3) changes in the rates of C input (i. e., steady state). We demonstrate the ability to compare residence times in contrasting sites, such Andisols and non-Andisols, and the ability to calculate residence times across a range of soil depths. We use ¹⁴C in a two-box model to quantify soil carbon turnover parameters in deforested dairy pastures under similar climate in the Tokomaru silt loam (non-Andisol) versus the Egmont black loam (Andisol), originally sampled in 1962, 1965 and 1969, and resampled again in 2008. The ¹⁴C-based residence times of the main soil C pool in surface soil (~8 cm) are ~9 years in the Tokomaru soils compared to ~17 years for the Egmont soils. This difference represents nearly a doubling of soil C residence time, and roughly explains the doubling of the soil C stock. Passive soil C comprises 15% of the soil C pool in Tokomaru soils versus 27% in Egmont soils. A similar difference in residence times is found in a second surface soil comparison between the Bruntwood soil (Andisol) and the Te Kowhai soil (non-Andisol) with residence times of 18 and 27 years, respectively. The comparisons support evidence that C dynamics do differ in Andisols versus non-Andisols, as a result of both the mineral allophane and Al complexation. Expanding our calculations beyond surface soil, we show that thickening the calculation depth by combining horizons allows robust residence times to be calculated at a range of depths. Overall, the large and systematically collected dataset demonstrate that soil C residence times of the main soil C pool can be routinely calculated using ¹⁴C wherever samples collected 10 or more years apart in New Zealand grassland soils are available, and presumably under similar circumstances in other soils worldwide.

text: Evaluating 50 years of time-series soil radiocarbon data: Towards routine calculation of robust C residence times In 1959, Athol Rafter began a substantial programme of monitoring the flow of ¹⁴C produced by atmospheric thermonuclear tests through New Zealand's atmosphere, biosphere and soil. By building on the original measurements through ongoing sampling, a database of over 500 soil radiocarbon measurements spanning 50 years has now been compiled. The datasets, including an 11-point time series, allow strong focus on the robust quantification of residence times ranging from years to decades. We describe key aspects of the dataset, including the ability to identify critical assumptions inherent in calculating soil C residence times. The 3 most critical assumptions relate to: (1) the proportion of old C ("fraction passive"), (2) the lag time between photosynthesis and C entering the modeled pool, and (3) changes in the rates of C input (i. e., steady state). We demonstrate the ability to compare residence times in contrasting sites, such Andisols and non-Andisols, and the ability to calculate residence times across a range of soil depths. We use ¹⁴C in a two-box model to quantify soil carbon turnover parameters in deforested dairy pastures under similar climate in the Tokomaru silt loam (non-Andisol) versus the Egmont black loam (Andisol), originally sampled in 1962, 1965 and 1969, and resampled again in 2008. The ¹⁴C-based residence times of the main soil C pool in surface soil (~8 cm) are ~9 years in the Tokomaru soils compared to ~17 years for the Egmont soils. This difference represents nearly a doubling of soil C residence time, and roughly explains the doubling of the soil C stock. Passive soil C comprises 15% of the soil C pool in Tokomaru soils versus 27% in Egmont soils. A similar difference in residence times is found in a second surface soil comparison between the Bruntwood soil (Andisol) and the Te Kowhai soil (non-Andisol) with residence times of 18 and 27 years, respectively. The comparisons support evidence that C dynamics do differ in Andisols versus non-Andisols, as a result of both the mineral allophane and Al complexation. Expanding our calculations beyond surface soil, we show that thickening the calculation depth by combining horizons allows robust residence times to be calculated at a range of depths. Overall, the large and systematically collected dataset demonstrate that soil C residence times of the main soil C pool can be routinely calculated using ¹⁴C wherever samples collected 10 or more years apart in New Zealand grassland soils are available, and presumably under similar circumstances in other soils worldwide.

year: 2013

title: Can you feel the pressure? Examining the effects of anxiety in elite netball shooters

authors: Tong, Georgia Terri

abstract: Netball is an increasingly popular sport for women in New Zealand, with the national league competition being fully professional. One important skill within netball is goal shooting, as the goal volume and accuracy ultimately decides the outcome of the game. Therefore, it is critical that shooters are able to perform this task well under pressure. The first part of this thesis reviews the literature on the effects of anxiety on sport performance. The second part of this thesis includes two studies. The first study, Study A (Chapter 2), was an observational, retrospective analysis of performance of 15 shooters in the top New Zealand competition at different score-lines and time points throughout netball games. The analysis showed that when one and two goals ahead, as well as other specific time points such as first shot of the quarter, the shooters shot significantly worse than the individual mean accuracy, but when three or four goals ahead the opposite effect occurred, a performance decrease. The fluctuation in performance demonstrated the possible influence of anxiety and individual differences on performance under pressure, along with the need to examine performance under pressure in a controlled setting in elite netball shooters. The second study, Study B (Chapter 3), was an experimental study designed to investigate the anxiety-performance relationship in elite netball athletes. Eleven elite netball shooters performed 100 shots at goal under four conditions: high-pressure defender present, high-pressure defender absent, low-pressure defender present, and low-pressure defender absent. Increased perceived anxiety, heart rate and task completion time occurred in the high-pressure conditions; however trait anxiety, concentration disruption in particular, predicted performance under low-pressure but not high-pressure conditions. In conclusion, the outcomes of these studies demonstrate that performance fluctuation occurs under pressure and that there may be individual differences in performance under pressure. The need for greater investigation of anxiety induced by high-pressure in elite professional netballers is apparent.

text: Can you feel the pressure? Examining the effects of anxiety in elite netball shooters Netball is an increasingly popular sport for women in New Zealand, with the national league competition being fully professional. One important skill within netball is goal shooting, as the goal volume and accuracy ultimately decides the outcome of the game. Therefore, it is critical that shooters are able to perform this task well under pressure. The first part of this thesis reviews the literature on the effects of anxiety on sport performance. The second part of this thesis includes two studies. The first study, Study A (Chapter 2), was an observational, retrospective analysis of performance of 15 shooters in the top New Zealand competition at different score-lines and time points throughout netball games. The analysis showed that when one and two goals ahead, as well as other specific time points such as first shot of the quarter, the shooters shot significantly worse than the individual mean accuracy, but when three or four goals ahead the opposite effect occurred, a performance decrease. The fluctuation in performance demonstrated the possible influence of anxiety and individual differences on performance under pressure, along with the need to examine performance under pressure in a controlled setting in elite netball shooters. The second study, Study B (Chapter 3), was an experimental study designed to investigate the anxiety-performance relationship in elite netball athletes. Eleven elite netball shooters performed 100 shots at goal under four conditions: high-pressure defender present, high-pressure defender absent, low-pressure defender present, and low-pressure defender absent. Increased perceived anxiety, heart rate and task completion time occurred in the high-pressure conditions; however trait anxiety, concentration disruption in particular, predicted performance under low-pressure but not high-pressure conditions. In conclusion, the outcomes of these studies demonstrate that performance fluctuation occurs under pressure and that there may be individual differences in performance under pressure. The need for greater investigation of anxiety induced by high-pressure in elite professional netballers is apparent.

year: 2019

title: It's harder in my language, but I still choose it

authors: Keegan, Te Taka Adrian Gregory

abstract: In New Zealand, the language that dominates most technologies is English. For a variety of reasons, interfaces have been made available in the Maori language for a range of modem technological tools. We have conducted usability studies on many of these products and fluent Maori users have almost unanimously stated that the products are more difficult and time consuming to use in the indigenous (Maori) language. They allude to unfamiliar instances and uses of Maori words, and to an ingrained familiarity with the English-language versions of these technologies, saying they would revert to the English-language interfaces if time is a factor. However, they also express a sense of pride at being able to see and use the Maori language in these various forms of media and state that although they experience some difficulty, the Maori-language versions would still be their first preference.

text: It's harder in my language, but I still choose it In New Zealand, the language that dominates most technologies is English. For a variety of reasons, interfaces have been made available in the Maori language for a range of modem technological tools. We have conducted usability studies on many of these products and fluent Maori users have almost unanimously stated that the products are more difficult and time consuming to use in the indigenous (Maori) language. They allude to unfamiliar instances and uses of Maori words, and to an ingrained familiarity with the English-language versions of these technologies, saying they would revert to the English-language interfaces if time is a factor. However, they also express a sense of pride at being able to see and use the Maori language in these various forms of media and state that although they experience some difficulty, the Maori-language versions would still be their first preference.

year: 2014