title: Mortality of native forest vegetation in the Kaimai ranges

authors: Jane, Graeme Travis

abstract: Vegetation mortality has been evident in the Kaimai Ranges, North Island, New Zealand for at least 40 years and affects a wide range of species and forest types. The mortality occurs above 550 m altitude and on each prominence has a lower limit which corresponds closely with the predominant cloud zone in each area. The severity of the damage ranges from complete mortality of canopy species to a light mosaic of killed trees. On individual trees damage may be evident as leader dieback reduced leaf size, and other symptoms suggestive of waterlogging. 
Mortality appears to be episodic and several age classes can be distinguished by vegetation height. Recent mortality can be reliably dated to droughts in 1972 and 1946 but forest age class structure suggests a number of earlier dates for similar episodes including 1656, 1804, 1861 and 1914. Many species do not survive for more than a portion of their potential life spans. Seral species do not reach their potential stature and minor droughts appear to trigger mortality releasing the more permanent species.
The distinct topographic and altitudinal bounds of the mortality and dendroclimatic analyses of mortality episodes suggested a strong direct drought effect. It was proposed that since the fog zone soil is frequently waterlogged, root systems would be restricted, and plants poorly able to respond to water stress. These proposals led to a series of investigations into plant water relations. 
An empirical model of pressure-volume curves was developed. Simple manipulation of the coefficients of the resultant function, provides estimates of osmotic potential and symplastic water content, and permits precise calculation of the bulk modulus of elasticity and turgor loss point. Osmotic potential was determined independently from freezing point depression measurement on leaf exudates and similar values were found. The bulk modulus of elasticity and the coefficient of elasticity are closely linked and variations in the pressure potential at the turgor loss point, was closely correlated with osmotic potential. 
During the summer 1981/2 water potential and stomatal aperture were monitored at a number of localities inside and outside the fog zone. Within the fog zone dawn water potentials remained high and were close to full turgor when overnight fog was present. Midday values generally compare with those published for plants of streamsides and wet habitats. Afternoon recovery was normally evident in all species except Quintinia acutifolia which was the least healthy of the species studied. 
Stomatal conductances in the seral species were high and those for the canopy species near usual values found in hardwood trees. Diurnal stomatal conductance patterns changed as the season progressed and late in the season closure often began before midday. Rapid closure at moderate temperatures appeared to be related to high vapour pressure deficit and generally minimised internal water stress. 
Fog lowers temperatures and light levels, for long intervals during the spring before and during budbreak slowing leaf development and maturation, and impairing stomatal development causing leaf scorch and leaf fall in fine weather. This results in part, from increased osmotic potential. 
Ranking of the species using the variability of the tissue water relations parameters indicates the presence of two distinct survival strategies; stress avoidance and stress tolerance. Similarly the effects of waterlogging could be avoided or tolerated and two canopy species (tawari and silver beech) appear to adopt opposing physiological and morphological strategies whereas the seral species maximise growth and are poorly adapted and intolerant of site induced stress.
Knowledge of the water relations of the cloud forest species provides a new perspective that allows a better understanding of the structure and function of the forests. The evidence suggests that in spite of the very wet environment, features of the cloud forest plants result from water stress. Evidence of adaptation to water stress supports the general hypothesis that drought is a significant factor in forest mortality within the Kaimai Ranges.

text: Mortality of native forest vegetation in the Kaimai ranges Vegetation mortality has been evident in the Kaimai Ranges, North Island, New Zealand for at least 40 years and affects a wide range of species and forest types. The mortality occurs above 550 m altitude and on each prominence has a lower limit which corresponds closely with the predominant cloud zone in each area. The severity of the damage ranges from complete mortality of canopy species to a light mosaic of killed trees. On individual trees damage may be evident as leader dieback reduced leaf size, and other symptoms suggestive of waterlogging. 
Mortality appears to be episodic and several age classes can be distinguished by vegetation height. Recent mortality can be reliably dated to droughts in 1972 and 1946 but forest age class structure suggests a number of earlier dates for similar episodes including 1656, 1804, 1861 and 1914. Many species do not survive for more than a portion of their potential life spans. Seral species do not reach their potential stature and minor droughts appear to trigger mortality releasing the more permanent species.
The distinct topographic and altitudinal bounds of the mortality and dendroclimatic analyses of mortality episodes suggested a strong direct drought effect. It was proposed that since the fog zone soil is frequently waterlogged, root systems would be restricted, and plants poorly able to respond to water stress. These proposals led to a series of investigations into plant water relations. 
An empirical model of pressure-volume curves was developed. Simple manipulation of the coefficients of the resultant function, provides estimates of osmotic potential and symplastic water content, and permits precise calculation of the bulk modulus of elasticity and turgor loss point. Osmotic potential was determined independently from freezing point depression measurement on leaf exudates and similar values were found. The bulk modulus of elasticity and the coefficient of elasticity are closely linked and variations in the pressure potential at the turgor loss point, was closely correlated with osmotic potential. 
During the summer 1981/2 water potential and stomatal aperture were monitored at a number of localities inside and outside the fog zone. Within the fog zone dawn water potentials remained high and were close to full turgor when overnight fog was present. Midday values generally compare with those published for plants of streamsides and wet habitats. Afternoon recovery was normally evident in all species except Quintinia acutifolia which was the least healthy of the species studied. 
Stomatal conductances in the seral species were high and those for the canopy species near usual values found in hardwood trees. Diurnal stomatal conductance patterns changed as the season progressed and late in the season closure often began before midday. Rapid closure at moderate temperatures appeared to be related to high vapour pressure deficit and generally minimised internal water stress. 
Fog lowers temperatures and light levels, for long intervals during the spring before and during budbreak slowing leaf development and maturation, and impairing stomatal development causing leaf scorch and leaf fall in fine weather. This results in part, from increased osmotic potential. 
Ranking of the species using the variability of the tissue water relations parameters indicates the presence of two distinct survival strategies; stress avoidance and stress tolerance. Similarly the effects of waterlogging could be avoided or tolerated and two canopy species (tawari and silver beech) appear to adopt opposing physiological and morphological strategies whereas the seral species maximise growth and are poorly adapted and intolerant of site induced stress.
Knowledge of the water relations of the cloud forest species provides a new perspective that allows a better understanding of the structure and function of the forests. The evidence suggests that in spite of the very wet environment, features of the cloud forest plants result from water stress. Evidence of adaptation to water stress supports the general hypothesis that drought is a significant factor in forest mortality within the Kaimai Ranges.

year: 1983

title: Evaluating soil and landscape models to predict liquefaction susceptibility in the Hinuera Formation, Hamilton Basin

authors: McKay, Aleesha May

abstract: The Hinuera Formation, being an extensive alluvial deposit throughout the Hamilton Basin plains, has been identified by Kleyburg (2015) as being susceptible to liquefaction. As much of the infrastructure of the Hamilton Basin is based on the Hinuera Formation, liquefaction thus poses a risk to the population of the area. This research project aims to develop a susceptibility model for liquefaction within the Hinuera Formation.
Cone Penetration Test (CPT) data collected during investigation for the Hamilton Section of the Waikato Expressway were acquired from the NZ Geotechnical Database. CLiqᵀᴹ software was used to analyse these data and determine the liquefaction potential index (LPI) of each CPT site. Soil map information (S-Map) was provided by Waikato Regional Council with the permission of Landcare Research, and Digital Elevation Data (DEM) by Waikato Regional Council. Parameters of slope, elevation, soil family and sibling number as well as the LPI derived from CLiqᵀᴹ were input into STATISTICAᵀᴹ and analysed using I-Tree analysis to determine the most influential factor to liquefaction. ArcGIS was then implemented to create landscape/soil models based on CLiqᵀᴹ data as well as calculations identified by statistical analysis.
The Hinuera Formation was found to have an overall susceptibility to liquefaction, ranging from low to high LPI dependant on depth. At a depth of 10 m, liquefaction potential on average was high, when compared to 3 and 5 m depths that showed a low to moderate LPI. At 3 m depth, which is most likely to show surface manifestation, liquefaction potential was low to moderate with the majority being considered as having a low LPI.

Soil textures ranged from coarse sand, to silt, to clay with few organics. When LPI was related to soil behaviour index (Ic) soil that had a ‘mixed’ texture of silty sand/sandy silt were most susceptible to liquefaction (~1.8-2.4 Ic). Much of the calculated liquefaction occurrence within CLiqᵀᴹ directly correlated to these sand/silt soil textures. Soil that was nearer to granular (coarse sand) or clay–like in behaviour were shown to likely inhibit liquefaction occurrence.
Soil family, a pedological map (and taxonomic) class, was shown to provide a good initial indication of the physical conditions of the underlying liquefiable soil, and therefore in turn liquefaction potential of land on the plains within the Hamilton Basin. A correlation between soil family and topography was identified using statistical analysis showing Utuhinaf and Kaipakif as most susceptible. Both Utuhinaf and Kaipakif soil families are of an organic texture (associated with peat formation). This observation led to the conclusion that areas of peat formation are likely correlated to the underlying soils having a relatively high susceptibility to liquefaction. This correlation is based on the knowledge that for peat formation to occur the land must have little relief (flat to a slight depression) and a high water table, both of which are prerequisites for liquefaction.
Elevation was also shown as a good initial indicator of liquefaction potential where a range between 38–39 m showed the highest liquefaction potential. When compared to a Digital Elevation Model (DEM) it was found that liquefaction potential was higher within interfluve and floodplain zones and lower in topography with a greater relief such as within the many paleo channels or low ridges of the Hamilton Basin. This is likely a result of the soil textures being finer with a higher silt component within the interfluve and floodplains due to the low energy depositional environment that is associated with these topographic features.
Based on the observations of soil family and topography being correlated to liquefaction susceptibility, two liquefaction susceptibility maps were developed to provide a preliminary assessment map.

text: Evaluating soil and landscape models to predict liquefaction susceptibility in the Hinuera Formation, Hamilton Basin The Hinuera Formation, being an extensive alluvial deposit throughout the Hamilton Basin plains, has been identified by Kleyburg (2015) as being susceptible to liquefaction. As much of the infrastructure of the Hamilton Basin is based on the Hinuera Formation, liquefaction thus poses a risk to the population of the area. This research project aims to develop a susceptibility model for liquefaction within the Hinuera Formation.
Cone Penetration Test (CPT) data collected during investigation for the Hamilton Section of the Waikato Expressway were acquired from the NZ Geotechnical Database. CLiqᵀᴹ software was used to analyse these data and determine the liquefaction potential index (LPI) of each CPT site. Soil map information (S-Map) was provided by Waikato Regional Council with the permission of Landcare Research, and Digital Elevation Data (DEM) by Waikato Regional Council. Parameters of slope, elevation, soil family and sibling number as well as the LPI derived from CLiqᵀᴹ were input into STATISTICAᵀᴹ and analysed using I-Tree analysis to determine the most influential factor to liquefaction. ArcGIS was then implemented to create landscape/soil models based on CLiqᵀᴹ data as well as calculations identified by statistical analysis.
The Hinuera Formation was found to have an overall susceptibility to liquefaction, ranging from low to high LPI dependant on depth. At a depth of 10 m, liquefaction potential on average was high, when compared to 3 and 5 m depths that showed a low to moderate LPI. At 3 m depth, which is most likely to show surface manifestation, liquefaction potential was low to moderate with the majority being considered as having a low LPI.

Soil textures ranged from coarse sand, to silt, to clay with few organics. When LPI was related to soil behaviour index (Ic) soil that had a ‘mixed’ texture of silty sand/sandy silt were most susceptible to liquefaction (~1.8-2.4 Ic). Much of the calculated liquefaction occurrence within CLiqᵀᴹ directly correlated to these sand/silt soil textures. Soil that was nearer to granular (coarse sand) or clay–like in behaviour were shown to likely inhibit liquefaction occurrence.
Soil family, a pedological map (and taxonomic) class, was shown to provide a good initial indication of the physical conditions of the underlying liquefiable soil, and therefore in turn liquefaction potential of land on the plains within the Hamilton Basin. A correlation between soil family and topography was identified using statistical analysis showing Utuhinaf and Kaipakif as most susceptible. Both Utuhinaf and Kaipakif soil families are of an organic texture (associated with peat formation). This observation led to the conclusion that areas of peat formation are likely correlated to the underlying soils having a relatively high susceptibility to liquefaction. This correlation is based on the knowledge that for peat formation to occur the land must have little relief (flat to a slight depression) and a high water table, both of which are prerequisites for liquefaction.
Elevation was also shown as a good initial indicator of liquefaction potential where a range between 38–39 m showed the highest liquefaction potential. When compared to a Digital Elevation Model (DEM) it was found that liquefaction potential was higher within interfluve and floodplain zones and lower in topography with a greater relief such as within the many paleo channels or low ridges of the Hamilton Basin. This is likely a result of the soil textures being finer with a higher silt component within the interfluve and floodplains due to the low energy depositional environment that is associated with these topographic features.
Based on the observations of soil family and topography being correlated to liquefaction susceptibility, two liquefaction susceptibility maps were developed to provide a preliminary assessment map.

year: 2017

title: The digital divide in New Zealand: The position of Maori and Pacific peoples

authors: Gibson, John

subjects: communication

abstract: Information and communication technology plays an ever-growing role in economic, political and social life and those who are unable to access such technologies are increasingly disadvantaged. Hence, what has come to be known as the 'digital divide' is of considerable significance. Here, indicators of that divide as it affects Maori and

text: The digital divide in New Zealand: The position of Maori and Pacific peoples Information and communication technology plays an ever-growing role in economic, political and social life and those who are unable to access such technologies are increasingly disadvantaged. Hence, what has come to be known as the 'digital divide' is of considerable significance. Here, indicators of that divide as it affects Maori and

year: 2002