title: Using model trees for classification

authors: Frank, Eibe

subjects: model trees

abstract: Model trees, which are a type of decision tree with linear regression functions at the leaves, form the basis of a recent successful technique for predicting continuous numeric values. They can be applied to classification problems by employing a standard method of transforming a classification problem into a problem of function approximation. Surprisingly, using this simple transformation the model tree inducer M5’, based on Quinlan’s M5, generates more accurate classifiers than the state-of-the-art decision tree learner C5.0, particularly when most of the attributes are numeric.

text: Using model trees for classification Model trees, which are a type of decision tree with linear regression functions at the leaves, form the basis of a recent successful technique for predicting continuous numeric values. They can be applied to classification problems by employing a standard method of transforming a classification problem into a problem of function approximation. Surprisingly, using this simple transformation the model tree inducer M5’, based on Quinlan’s M5, generates more accurate classifiers than the state-of-the-art decision tree learner C5.0, particularly when most of the attributes are numeric.

year: 1997-04

title: The ecological implications of reconstructed historic hydrodynamic conditions in Tauranga Harbour (1852-2006).

authors: Moffatt, Ariana

subjects: Tauranga Harbour

abstract: In order to manage, restore and mitigate the increasing anthropogenic impacts on estuarine systems in the future, it is useful to understand the magnitude and distribution of historic changes in environmental conditions that may have impacted on ecosystems through time. The general aim of this thesis is to hind cast historic environmental conditions in order to investigate the ecological implications of changes in geomorphology and hydrodynamics within the southern basin of Tauranga Harbour. This was achieved by compiling 11 bathymetries and developing a hydrodynamic numerical model. 
The bathymetries produced were from 1852, 1879, 1901, 1927, 1954 and 2006 (entrance adjusted bathymetries). An additional 5 bathymetries from 1852, 1879, 1901, 1927 and 1954 were compiled which had sediment removed from the intertidal areas to simulate infilling (intertidal adjusted bathymetries). The impact of the simulated infilling on depth Investigate the by comparing the entrance adjusted bathymetries with the intertidal adjusted bathymetries of each year. Using the numerical modelling environment Delft3D a numerical model of the southern basin of Tauranga harbour was developed to simulate historical hydrodynamic conditions for each of the 11 bathymetries. The impact of the simulated infilling on hydrodynamics was investigated by comparing the results of the entrance adjusted and intertidal adjusted numerical models of each year. The modelled hydrodynamic conditions of current speed, water level range and tracer decay from the intertidal adjusted bathymetries were used to investigate temporal changes in environmental conditions that may have influenced historic ecological health and distribution of species. 
The comparison of depth and hydrodynamics between the entrance and intertidal bathymetries for each year showed that the simulated infilling caused slight changes in the distribution of depth and a slight increase in the magnitude of current speed, water level range and rate of tracer decay. 
The temporal changes in the environmental conditions included large magnitude small scale changes in depth and current speed occurred in the harbour entrance channels. Water level had the most significant change prior to dredging across the Harbour potentially due to historic changes in the inlet cross-section. For depth, water level and current speed the 2006 conditions were most different to the earliest 1852 conditions. This is due to the accumulation of both large natural changes in geomorphology and hydrodynamics and changes from the anthropogenic dredging and development. The tracer decay had most difference through time in the regions with changes in the constricted entrance such as in the estuaries above Sulphur Point.
Significant ecological implications include changes in depth and water level influencing functions such as bivalve feeding times, inundation of mangroves and light attenuation for seagrass. A significant change through time as a result of the intertidal infilling is the predicted expansion of mangroves. Differences in current speeds would alter the distribution of sediment and species as well as the settlement of larvae. Residence times have had largescale changes due to the anthropogenic changes around port development. These changes would result in an increase in the retention of sediments, contaminants and larvae and a shift from bivalve dominance to polychaete’s as well as altered community connectivity.

text: The ecological implications of reconstructed historic hydrodynamic conditions in Tauranga Harbour (1852-2006). In order to manage, restore and mitigate the increasing anthropogenic impacts on estuarine systems in the future, it is useful to understand the magnitude and distribution of historic changes in environmental conditions that may have impacted on ecosystems through time. The general aim of this thesis is to hind cast historic environmental conditions in order to investigate the ecological implications of changes in geomorphology and hydrodynamics within the southern basin of Tauranga Harbour. This was achieved by compiling 11 bathymetries and developing a hydrodynamic numerical model. 
The bathymetries produced were from 1852, 1879, 1901, 1927, 1954 and 2006 (entrance adjusted bathymetries). An additional 5 bathymetries from 1852, 1879, 1901, 1927 and 1954 were compiled which had sediment removed from the intertidal areas to simulate infilling (intertidal adjusted bathymetries). The impact of the simulated infilling on depth Investigate the by comparing the entrance adjusted bathymetries with the intertidal adjusted bathymetries of each year. Using the numerical modelling environment Delft3D a numerical model of the southern basin of Tauranga harbour was developed to simulate historical hydrodynamic conditions for each of the 11 bathymetries. The impact of the simulated infilling on hydrodynamics was investigated by comparing the results of the entrance adjusted and intertidal adjusted numerical models of each year. The modelled hydrodynamic conditions of current speed, water level range and tracer decay from the intertidal adjusted bathymetries were used to investigate temporal changes in environmental conditions that may have influenced historic ecological health and distribution of species. 
The comparison of depth and hydrodynamics between the entrance and intertidal bathymetries for each year showed that the simulated infilling caused slight changes in the distribution of depth and a slight increase in the magnitude of current speed, water level range and rate of tracer decay. 
The temporal changes in the environmental conditions included large magnitude small scale changes in depth and current speed occurred in the harbour entrance channels. Water level had the most significant change prior to dredging across the Harbour potentially due to historic changes in the inlet cross-section. For depth, water level and current speed the 2006 conditions were most different to the earliest 1852 conditions. This is due to the accumulation of both large natural changes in geomorphology and hydrodynamics and changes from the anthropogenic dredging and development. The tracer decay had most difference through time in the regions with changes in the constricted entrance such as in the estuaries above Sulphur Point.
Significant ecological implications include changes in depth and water level influencing functions such as bivalve feeding times, inundation of mangroves and light attenuation for seagrass. A significant change through time as a result of the intertidal infilling is the predicted expansion of mangroves. Differences in current speeds would alter the distribution of sediment and species as well as the settlement of larvae. Residence times have had largescale changes due to the anthropogenic changes around port development. These changes would result in an increase in the retention of sediments, contaminants and larvae and a shift from bivalve dominance to polychaete’s as well as altered community connectivity.

year: 2021

title: Tephras and New Zealand archaeology

authors: Lowe, David J.

subjects: tephrochronology

abstract: Establishing an accurate date for earliest Polynesian settlement in New Zealand is essential for understanding patterns of settlement and associated environmental impacts, and the processes and rates of cultural change in Eastern Polynesia. Tephra deposits from five volcanic centres, together with exotic sea-rafted pumice, provide isochronous constraints on the timing of earliest settlement and human impacts in northern New Zealand. A local basaltic tephra from Rangitoto Island (Auckland) and locally distributed andesitic tephras from Egmont volcano directly date human occupation to c. AD 1400–1450. Distal andesitic tephras (Tufa Trig Formation) from Mt Ruapehu, Tongariro volcanic centre, help constrain the timing of earliest anthropogenic deforestation signals in Hawke's Bay. Sea-rafted Loisels Pumice(s), although of uncertain stratigraphic reliability in places, overlies cultural remains that can be no younger than c. AD 1350 along the east coast, North Island. The regionally extensive rhyolitic Kaharoa Tephra, which erupted from Okataina volcano between c. AD  1300–1390, is the critical “settlement layer” datum for dating prehistory in the North Island: no human artefacts are recorded beneath it and the earliest inferred environmental impacts by humans are dated to c. AD  1280, just prior to its deposition. This maximum date matches the earliest radiocarbon dates derived for both settlement and human impacts from archaeological and natural sites (c. AD 1250), and implies that the onset of deforestation was essentially contemporaneous with initial settlement.
The widespread rhyolitic Taupo Tephra, which erupted from Taupo volcano c. AD 200, provides an isochronous benchmark well before earliest settlement. The tephra may coincide approximately with a putative earlier transient contact in New Zealand based on Pacific rat-bone (Rattus exulans) dates. More precise calendrical dates on the tephras—via dendrochronology or ice-core records or other dating methods—would help refine assessment of the timing of earliest settlement, while extending the distributional range of critical tephra layers, through application of crypto-tephra analysis, could lead to a greater understanding of settlement patterns.

text: Tephras and New Zealand archaeology Establishing an accurate date for earliest Polynesian settlement in New Zealand is essential for understanding patterns of settlement and associated environmental impacts, and the processes and rates of cultural change in Eastern Polynesia. Tephra deposits from five volcanic centres, together with exotic sea-rafted pumice, provide isochronous constraints on the timing of earliest settlement and human impacts in northern New Zealand. A local basaltic tephra from Rangitoto Island (Auckland) and locally distributed andesitic tephras from Egmont volcano directly date human occupation to c. AD 1400–1450. Distal andesitic tephras (Tufa Trig Formation) from Mt Ruapehu, Tongariro volcanic centre, help constrain the timing of earliest anthropogenic deforestation signals in Hawke's Bay. Sea-rafted Loisels Pumice(s), although of uncertain stratigraphic reliability in places, overlies cultural remains that can be no younger than c. AD 1350 along the east coast, North Island. The regionally extensive rhyolitic Kaharoa Tephra, which erupted from Okataina volcano between c. AD  1300–1390, is the critical “settlement layer” datum for dating prehistory in the North Island: no human artefacts are recorded beneath it and the earliest inferred environmental impacts by humans are dated to c. AD  1280, just prior to its deposition. This maximum date matches the earliest radiocarbon dates derived for both settlement and human impacts from archaeological and natural sites (c. AD 1250), and implies that the onset of deforestation was essentially contemporaneous with initial settlement.
The widespread rhyolitic Taupo Tephra, which erupted from Taupo volcano c. AD 200, provides an isochronous benchmark well before earliest settlement. The tephra may coincide approximately with a putative earlier transient contact in New Zealand based on Pacific rat-bone (Rattus exulans) dates. More precise calendrical dates on the tephras—via dendrochronology or ice-core records or other dating methods—would help refine assessment of the timing of earliest settlement, while extending the distributional range of critical tephra layers, through application of crypto-tephra analysis, could lead to a greater understanding of settlement patterns.

year: 2000