title: Use of shallow samples to estimate the total carbon storage in pastoral soils

authors: Kelliher, Francis M.

subjects: soil

abstract: Using data from pastoral soils sampled by horizon at 56 locations across New Zealand, we conducted a meta-analysis. On average, the total depth sampled was 0.93 ± 0.026 m (± SEM), and on a volumetric basis, the total C storage averaged 26.9 ± 1.8, 13.9 ± 0.6 and 9.2 ± 1.4 kg C m⁻² for allophanic (n=12), non-allophanic (n=40) and pumice soils (n=4), respectively. We estimated the total C storage, and quantified the uncertainty, using the data for samples taken from the uppermost A-horizon whose depth averaged 0.1 ± 0.003 m. For A-horizon samples of the allophanic soils, the mean C content was 108 ± 6 g C kg⁻¹ and the bulk density was 772 ± 29 kg m⁻³, for non-allophanic soils they were 51 ± 4 g C kg⁻¹ and 1055 ± 29 kg m⁻³, and for pumice soils they were 68 ± 9 g C kg⁻¹ and 715 ± 45 kg m⁻³. The C density —a product of the C content and bulk density —of the A-horizon samples was proportional to their air-dried water content, a proxy measure for the mineral surface area. By linear regression with C density of the A-horizon, the total C storage could be estimated with a standard error of 3.1 kg C m⁻², 19% of the overall mean.

text: Use of shallow samples to estimate the total carbon storage in pastoral soils Using data from pastoral soils sampled by horizon at 56 locations across New Zealand, we conducted a meta-analysis. On average, the total depth sampled was 0.93 ± 0.026 m (± SEM), and on a volumetric basis, the total C storage averaged 26.9 ± 1.8, 13.9 ± 0.6 and 9.2 ± 1.4 kg C m⁻² for allophanic (n=12), non-allophanic (n=40) and pumice soils (n=4), respectively. We estimated the total C storage, and quantified the uncertainty, using the data for samples taken from the uppermost A-horizon whose depth averaged 0.1 ± 0.003 m. For A-horizon samples of the allophanic soils, the mean C content was 108 ± 6 g C kg⁻¹ and the bulk density was 772 ± 29 kg m⁻³, for non-allophanic soils they were 51 ± 4 g C kg⁻¹ and 1055 ± 29 kg m⁻³, and for pumice soils they were 68 ± 9 g C kg⁻¹ and 715 ± 45 kg m⁻³. The C density —a product of the C content and bulk density —of the A-horizon samples was proportional to their air-dried water content, a proxy measure for the mineral surface area. By linear regression with C density of the A-horizon, the total C storage could be estimated with a standard error of 3.1 kg C m⁻², 19% of the overall mean.

year: 2013

title: Estimating patterns and rates of coastal cliff retreat around Tauranga Harbour

authors: Garae, Camillia Pauline

subjects: rate of coastal cliff retreat

abstract: Cliffs are common around the shores of Tauranga Harbour, including in the urban areas. The existence of cliffs indicates a potential hazard to people living close to the cliff edge, as they imply both a tendency for the upper surfaces to erode, and for the debris to fall onto lower areas. To identify the relative risk around the harbour shoreline, it is useful to determine the rates and patterns of shoreline erosion.

This study initially determined the shoreline changes between 1943, 1982 and 2011 using a combination of aerial photograph analysis using Digital Shoreline Analysis System (DSAS), airborne LiDAR data and Laser scan data. Long term rate of retreat was determined for the study area with the use of digitised aerial photographs and DSAS applications. Cliff locations are often difficult to determine from aerial photographs due to shadows and vegetation obscuring the ground surface. Hence, LiDAR data were used to initially identify the cliff edge positions in 2011. These results were compared to the 2011 aerial photograph to assess how easily the cliff edge can be identified with the photographs. The inferred cliff edge from the 2011 aerial photograph was digitised in GIS, and the corresponding cliff edge for 1943 was also determined and digitised using stereopairs to aid cliff edge identification. The 1982 aerial photograph was scanned, georeferenced and shoreline digitised. Using the DSAS software, the rates were computed. However, this was also compared to other methods using the intersection points generated from DSAS. Laser scan surveys were conducted to determine surface volume changes to acquire short term rate of retreat at the cliff face. This analysis involved surveys carried out within a period from May 2014, July 2014 – November 2014. The data collected was compared to earlier laser scan data from September 2012 – July 2013 and LiDAR data from September 2011.

Several approaches were used to determine the best estimate of rate of retreat from the DSAS analyses. It was identified that the buffer end-point rate produced the best rate cliff retreat in the study area. The range of rate of retreat using this method was -0.2 ± 0.16 to 0.07 ± 0.16 m.y-1. It was also identified that the Matua Subgroup had the highest rate of erosion within the study area located at South west Matakana Island. The rate was lowest at East Pahoia Peninsula. Although laser scans were conducted only over a short period of time, comparing the dataset to earlier laser scan data a range of rates were obtained -0.01 to 0.02 m.y-1. Although rates were determined for both methods the errors were large and need to be considered.

text: Estimating patterns and rates of coastal cliff retreat around Tauranga Harbour Cliffs are common around the shores of Tauranga Harbour, including in the urban areas. The existence of cliffs indicates a potential hazard to people living close to the cliff edge, as they imply both a tendency for the upper surfaces to erode, and for the debris to fall onto lower areas. To identify the relative risk around the harbour shoreline, it is useful to determine the rates and patterns of shoreline erosion.

This study initially determined the shoreline changes between 1943, 1982 and 2011 using a combination of aerial photograph analysis using Digital Shoreline Analysis System (DSAS), airborne LiDAR data and Laser scan data. Long term rate of retreat was determined for the study area with the use of digitised aerial photographs and DSAS applications. Cliff locations are often difficult to determine from aerial photographs due to shadows and vegetation obscuring the ground surface. Hence, LiDAR data were used to initially identify the cliff edge positions in 2011. These results were compared to the 2011 aerial photograph to assess how easily the cliff edge can be identified with the photographs. The inferred cliff edge from the 2011 aerial photograph was digitised in GIS, and the corresponding cliff edge for 1943 was also determined and digitised using stereopairs to aid cliff edge identification. The 1982 aerial photograph was scanned, georeferenced and shoreline digitised. Using the DSAS software, the rates were computed. However, this was also compared to other methods using the intersection points generated from DSAS. Laser scan surveys were conducted to determine surface volume changes to acquire short term rate of retreat at the cliff face. This analysis involved surveys carried out within a period from May 2014, July 2014 – November 2014. The data collected was compared to earlier laser scan data from September 2012 – July 2013 and LiDAR data from September 2011.

Several approaches were used to determine the best estimate of rate of retreat from the DSAS analyses. It was identified that the buffer end-point rate produced the best rate cliff retreat in the study area. The range of rate of retreat using this method was -0.2 ± 0.16 to 0.07 ± 0.16 m.y-1. It was also identified that the Matua Subgroup had the highest rate of erosion within the study area located at South west Matakana Island. The rate was lowest at East Pahoia Peninsula. Although laser scans were conducted only over a short period of time, comparing the dataset to earlier laser scan data a range of rates were obtained -0.01 to 0.02 m.y-1. Although rates were determined for both methods the errors were large and need to be considered.

year: 2015

title: Racism and Employment: A Narrative Review of Aotearoa New Zealand and International Qualitative Studies

authors: Tan, Kyle K. H.

abstract: In Aotearoa New Zealand, employment inequities exist for minoritised ethnic groups (Māori, Pasifika, Asian, racialised migrants and refugees) in the forms of barriers to employment, occupation inequities, differences in promotion to leadership roles, ethnic pay gaps and discriminatory experiences at workplaces. In this review, we compiled Aotearoa qualitative studies to depict the dynamics of racism alongside other intersectional forms of prejudices that disadvantage the employment processes and career progression of minoritised ethnicities. Literature gaps in Aotearoa research were identified through reviewing international literature published between 2016 and 2021. Reviewed Aotearoa studies were categorised into three themes: unemployment and underemployment, workplace discrimination, and strategies for navigating racism. Drawing upon a framework that recognises racialised processes as spanning across micro- (individual), meso- (organisational) and macro- (institutional) levels, we found most Aotearoa studies analysing racism in the workplace focus on micro-level experiences. Compared with international literature, research in Aotearoa has yet to consider the roles of organisations and technologies as racialised structures that engender employment inequities, and the interaction of individuals in response to meso- and macro-structures that build on settler colonialism and racism. Our review echoes the call of Aotearoa scholars to name racism as the overarching oppressive mechanism embedded within organisations and to use anti-racism praxes such as te Tiriti o Waitangi as a way forward to promote employment equity.

text: Racism and Employment: A Narrative Review of Aotearoa New Zealand and International Qualitative Studies In Aotearoa New Zealand, employment inequities exist for minoritised ethnic groups (Māori, Pasifika, Asian, racialised migrants and refugees) in the forms of barriers to employment, occupation inequities, differences in promotion to leadership roles, ethnic pay gaps and discriminatory experiences at workplaces. In this review, we compiled Aotearoa qualitative studies to depict the dynamics of racism alongside other intersectional forms of prejudices that disadvantage the employment processes and career progression of minoritised ethnicities. Literature gaps in Aotearoa research were identified through reviewing international literature published between 2016 and 2021. Reviewed Aotearoa studies were categorised into three themes: unemployment and underemployment, workplace discrimination, and strategies for navigating racism. Drawing upon a framework that recognises racialised processes as spanning across micro- (individual), meso- (organisational) and macro- (institutional) levels, we found most Aotearoa studies analysing racism in the workplace focus on micro-level experiences. Compared with international literature, research in Aotearoa has yet to consider the roles of organisations and technologies as racialised structures that engender employment inequities, and the interaction of individuals in response to meso- and macro-structures that build on settler colonialism and racism. Our review echoes the call of Aotearoa scholars to name racism as the overarching oppressive mechanism embedded within organisations and to use anti-racism praxes such as te Tiriti o Waitangi as a way forward to promote employment equity.

year: 2024-01-01