title: Soil recovery on landslides in hill country at Whatawhata Research Station, western Waikato, New Zealand

authors: Noyes, Adrea Morgan

subjects: Landslides

abstract: My thesis investigates soil recovery following landsliding in steepland and hill country on part of the Whatawhata Research Station, 25 km west of Hamilton, North Island, New Zealand.  Underlain mainly by Mesozoic greywacke, six landslides were studied, ranging in activation time from pre-1953 to 2014.  On the basis of geomorphological analysis the landslides were divided into five zones: shear zones (mean of 25 % of landslide area), intact accumulation zones (20 %), transition zones (40 %), and re-deposition zones (15 %), plus an adjacent control zone.  Soil physical and chemical properties including: solum depth, A horizon depth, particle size, and soil dry bulk density, along with, soil C, N, P, and pH were determined for each zone of each landslide.  
Soils were well-developed in the control and intact accumulation zones and least recovered in the shear and re-deposition zones.  Mean A horizon depths ranged from 2 cm in the shear and re-deposition zones to 7 cm in the transition zones, 17 cm in the intact accumulation zones, and 20 cm in the control.  Mean solum depths ranged from 24 cm in the shear zones, 91 cm in the intact accumulation zones, 72 cm in the transition zones, 90 cm in the re-deposition zones and >100 cm in the control zones.
The differences between zones within the landslides were greater than the differences between landslides.  The controls had higher (P<0.05) C contents than any of the zones within the landslides, and the intact accumulation zones had higher (P<0.05) C contents than the shear, transition or re-deposition zones.  Mean soil C contents ranged from 8.2 % in the controls through 5.4 % (intact accumulation zones), 4.2 % (transition zones), 3.2 % (re-deposition zones) to 2.6 % in the shear zones.
Similarly to C, the total N was higher in the controls than the other zones (P<0.05).  Mean N content ranged from 0.2 % in the shear zones, 0.3 % in the transition and re-deposition zones, 0.5 % in the intact accumulation zones to 0.7 % in the control zones.
The C:N ratio was consistent across all zones in all six landslides and controls, ranging from 11 to 16.  There were no significant differences in the C:N ratio between zones of the landslides or with landslide age.
Soil Olsen P was lower (P<0.05) in the shear and re-deposition zones than the control, intact accumulation, and transition zones.  There were no significant differences in Olsen P between the intact accumulation, transition, and control zones.  Soil pH was generally low (4.8 to 5.6) across all zones in all six landslides and soil dry bulk density was variable.  Thus soil pH, dry bulk density, and Olsen P were not correlated with soil recovery and development.
Overall the shear zone occupied <25 % of the landslide area, was the slowest zone to recover, and was the least productive.  The intact accumulation, transition, and re-deposition zones generally consisted of about 75 % of the landslide area, and once stabilised were expected to be relatively productive.

text: Soil recovery on landslides in hill country at Whatawhata Research Station, western Waikato, New Zealand My thesis investigates soil recovery following landsliding in steepland and hill country on part of the Whatawhata Research Station, 25 km west of Hamilton, North Island, New Zealand.  Underlain mainly by Mesozoic greywacke, six landslides were studied, ranging in activation time from pre-1953 to 2014.  On the basis of geomorphological analysis the landslides were divided into five zones: shear zones (mean of 25 % of landslide area), intact accumulation zones (20 %), transition zones (40 %), and re-deposition zones (15 %), plus an adjacent control zone.  Soil physical and chemical properties including: solum depth, A horizon depth, particle size, and soil dry bulk density, along with, soil C, N, P, and pH were determined for each zone of each landslide.  
Soils were well-developed in the control and intact accumulation zones and least recovered in the shear and re-deposition zones.  Mean A horizon depths ranged from 2 cm in the shear and re-deposition zones to 7 cm in the transition zones, 17 cm in the intact accumulation zones, and 20 cm in the control.  Mean solum depths ranged from 24 cm in the shear zones, 91 cm in the intact accumulation zones, 72 cm in the transition zones, 90 cm in the re-deposition zones and >100 cm in the control zones.
The differences between zones within the landslides were greater than the differences between landslides.  The controls had higher (P<0.05) C contents than any of the zones within the landslides, and the intact accumulation zones had higher (P<0.05) C contents than the shear, transition or re-deposition zones.  Mean soil C contents ranged from 8.2 % in the controls through 5.4 % (intact accumulation zones), 4.2 % (transition zones), 3.2 % (re-deposition zones) to 2.6 % in the shear zones.
Similarly to C, the total N was higher in the controls than the other zones (P<0.05).  Mean N content ranged from 0.2 % in the shear zones, 0.3 % in the transition and re-deposition zones, 0.5 % in the intact accumulation zones to 0.7 % in the control zones.
The C:N ratio was consistent across all zones in all six landslides and controls, ranging from 11 to 16.  There were no significant differences in the C:N ratio between zones of the landslides or with landslide age.
Soil Olsen P was lower (P<0.05) in the shear and re-deposition zones than the control, intact accumulation, and transition zones.  There were no significant differences in Olsen P between the intact accumulation, transition, and control zones.  Soil pH was generally low (4.8 to 5.6) across all zones in all six landslides and soil dry bulk density was variable.  Thus soil pH, dry bulk density, and Olsen P were not correlated with soil recovery and development.
Overall the shear zone occupied <25 % of the landslide area, was the slowest zone to recover, and was the least productive.  The intact accumulation, transition, and re-deposition zones generally consisted of about 75 % of the landslide area, and once stabilised were expected to be relatively productive.

year: 2016

title: How effective is Cauchy-EDA in high dimensions?

authors: Sanyang, Momodou L.

subjects: Machine learning

abstract: We consider the problem of high dimensional blackbox optimisation via Estimation of Distribution Algorithms (EDA) and the use of heavy-tailed search distributions in this setting. Some authors have suggested that employing a heavy tailed search distribution, such as a Cauchy, may make EDA better explore a high dimensional search space. However, other authors have found Cauchy search distributions are less effective than Gaussian search distributions in high dimensional problems. In this paper, we set out to resolve this controversy. To achieve this we run extensive experiments on a battery of high-dimensional test functions, and develop some theory which shows that small search steps are always more likely to move the search distribution towards the global optimum than large ones and, in particular, large search steps in high-dimensional spaces nearly always do badly in this respect. We hypothesise that, since exploration by large steps is mostly counterproductive in high dimensions, and since the fraction of good directions decays exponentially fast with increasing dimension, instead one should focus mainly on finding the right direction in which to move the search distribution. We propose a minor change to standard Gaussian EDA which implicitly achieves this aim, and our experiments on a sequence of test functions confirm the good performance of our new approach.

text: How effective is Cauchy-EDA in high dimensions? We consider the problem of high dimensional blackbox optimisation via Estimation of Distribution Algorithms (EDA) and the use of heavy-tailed search distributions in this setting. Some authors have suggested that employing a heavy tailed search distribution, such as a Cauchy, may make EDA better explore a high dimensional search space. However, other authors have found Cauchy search distributions are less effective than Gaussian search distributions in high dimensional problems. In this paper, we set out to resolve this controversy. To achieve this we run extensive experiments on a battery of high-dimensional test functions, and develop some theory which shows that small search steps are always more likely to move the search distribution towards the global optimum than large ones and, in particular, large search steps in high-dimensional spaces nearly always do badly in this respect. We hypothesise that, since exploration by large steps is mostly counterproductive in high dimensions, and since the fraction of good directions decays exponentially fast with increasing dimension, instead one should focus mainly on finding the right direction in which to move the search distribution. We propose a minor change to standard Gaussian EDA which implicitly achieves this aim, and our experiments on a sequence of test functions confirm the good performance of our new approach.

year: 2016

title: Te Kahautu Maxwell on Te Kooti and Ringatu (Interviewed by Tama Muru)

authors: Maxwell, Te Kahautu

abstract: In October 1869 musket fire erupted at Te Porere about sixty kilometres north of here, in the shadow of Mount Tongariro in the last major battle of the New Zealand wars. 

Armed constabulary and Maori fighters, clashed with the forces of the prophet Te Kooti Arikinui Te Turiki who had built an earth redoubt at Te Porere.  It was overwhelmed during the battle, but Te Kooti and his surviving followers escaped. 

Today the site is a tourist attraction but what also endured is the Ringatu Church, founded by Te Kooti. In 2018 it celebrated its 150th anniversary. 

Ringatu mixes the Bible with Maori custom and, like Matariki, follows annual cycles such as Te Huamata in June for planting and Te Pure, the harvest, each November. 

We spoke to Professor Te Kahautu Maxwell , a minister in the Ringatu Church and a senior academic in Maori and Indigenous Studies at the University of Waikato.

text: Te Kahautu Maxwell on Te Kooti and Ringatu (Interviewed by Tama Muru) In October 1869 musket fire erupted at Te Porere about sixty kilometres north of here, in the shadow of Mount Tongariro in the last major battle of the New Zealand wars. 

Armed constabulary and Maori fighters, clashed with the forces of the prophet Te Kooti Arikinui Te Turiki who had built an earth redoubt at Te Porere.  It was overwhelmed during the battle, but Te Kooti and his surviving followers escaped. 

Today the site is a tourist attraction but what also endured is the Ringatu Church, founded by Te Kooti. In 2018 it celebrated its 150th anniversary. 

Ringatu mixes the Bible with Maori custom and, like Matariki, follows annual cycles such as Te Huamata in June for planting and Te Pure, the harvest, each November. 

We spoke to Professor Te Kahautu Maxwell , a minister in the Ringatu Church and a senior academic in Maori and Indigenous Studies at the University of Waikato.

year: 2025