title: Comparison of spatial prediction techniques for developing Pinus radiata productivity surfaces across New Zealand

authors: Palmer, David John

subjects: plantation forestry

abstract: Spatial interpolation is frequently used to predict values across a landscape enabling the spatial variation and patterns of a property to be quantified. Inverse distance weighting (IDW), ordinary kriging (OK), regression kriging (RK), and partial least squares (PLS) regression are interpolation techniques typically used where the region of interest's spatial extent is relatively small and observations are numerous and regularly spaced. In the current era of data ‘mining’ and utilisation of sparse data, the above criteria are not always fully met, increasing model uncertainties. Furthermore, regression modelling and kriging techniques require good judgement, experience, and expertise by the practitioner compared with IDW with its more rudimentary approach. In this study we compared spatial predictions derived from IDW, PLS, RK, and OK for Pinus radiata volume mean annual increment (referred to as 300 Index) and mean top height at age twenty (referred to as Site Index) across New Zealand using cross-validation techniques. Validation statistics (RMSE, ME, and R2) show that RK, OK, and IDW provided predictions that were less biased and of greater accuracy than PLS predictions. Standard deviation of rank (SDR) and mean rank (MR) validation statistics showed similar results with OK the most consistent (SDR) predictor, whereas RK had the lowest mean rank (MR), closely followed by IDW. However, the mean performance rankings for validation observations classified according to their distance to the nearest model data point indicate that although PLS provided the poorest predictions at relatively close separation distances (<2 km), in the medium range ( 4–8 km) performance was of similar ranking to that of the other techniques, and at greater separation distances PLS outperformed the other techniques. Maps illustrating the spatial variation of P. radiata forest productivity are provided.

text: Comparison of spatial prediction techniques for developing Pinus radiata productivity surfaces across New Zealand Spatial interpolation is frequently used to predict values across a landscape enabling the spatial variation and patterns of a property to be quantified. Inverse distance weighting (IDW), ordinary kriging (OK), regression kriging (RK), and partial least squares (PLS) regression are interpolation techniques typically used where the region of interest's spatial extent is relatively small and observations are numerous and regularly spaced. In the current era of data ‘mining’ and utilisation of sparse data, the above criteria are not always fully met, increasing model uncertainties. Furthermore, regression modelling and kriging techniques require good judgement, experience, and expertise by the practitioner compared with IDW with its more rudimentary approach. In this study we compared spatial predictions derived from IDW, PLS, RK, and OK for Pinus radiata volume mean annual increment (referred to as 300 Index) and mean top height at age twenty (referred to as Site Index) across New Zealand using cross-validation techniques. Validation statistics (RMSE, ME, and R2) show that RK, OK, and IDW provided predictions that were less biased and of greater accuracy than PLS predictions. Standard deviation of rank (SDR) and mean rank (MR) validation statistics showed similar results with OK the most consistent (SDR) predictor, whereas RK had the lowest mean rank (MR), closely followed by IDW. However, the mean performance rankings for validation observations classified according to their distance to the nearest model data point indicate that although PLS provided the poorest predictions at relatively close separation distances (<2 km), in the medium range ( 4–8 km) performance was of similar ranking to that of the other techniques, and at greater separation distances PLS outperformed the other techniques. Maps illustrating the spatial variation of P. radiata forest productivity are provided.

year: 2009

title: A 'third way' in industry training: New Zealand's adaptation of selected British policies

authors: Piercy, Gemma Louise

subjects: industrial relations

abstract: This article has three integrated purposes. It seeks to provide insights into some of the ways in which:
British policies and programmes historically and more recently have influenced New Zealand initiatives in industry training;
those policies and programmes have been adapted to meet the country’s particular circumstances; and
unions have influenced aspects of the adaptation and implementation.

text: A 'third way' in industry training: New Zealand's adaptation of selected British policies This article has three integrated purposes. It seeks to provide insights into some of the ways in which:
British policies and programmes historically and more recently have influenced New Zealand initiatives in industry training;
those policies and programmes have been adapted to meet the country’s particular circumstances; and
unions have influenced aspects of the adaptation and implementation.

year: 2002

title: Boat electrofishing surveys of fish populations in the Ohau Channel in 2011 and 2012

authors: Hicks, Brendan J.

abstract: The aim of the survey was to provide on-going monitoring of the fish communities and abundance in the Ohau Channel, especially fish species that are taonga to Maori (eels, goldfish, and koura). In the current study we present the findings from the fifth and sixth years of sampling (2011 and 2012) in view of previous surveys using boat electrofishing in the Ohau Channel.

We used the University of Waikato’s 4.5 m-long, aluminium-hulled electrofishing boat to catch a total of 399 fish (29.4 kg) from 10 sites in 2011 (2,420 linear m, 9,680 m² area) and 301 fish (12.8 kg) at 11 sites in 2012 (3,625 linear m, 14,500 m² area). Koura and 7 fish species were present in both years, with common bully the most abundant in 2011 and common smelt the most abundant in 2012. Common smelt were more abundant in 2012 (131 fish) than in 2011 (39 fish). Goldfish were most abundant at sites in the lower channel, especially at site 7.

As reflected in total numbers, common bullies had the highest densities of any fish species in 2011 (up to 7.4 fish 100 m⁻²), the majority of which were taken from edge habitats at sites 4, 5 and site 7. In 2012, common bully abundance was much reduced. However, despite the lower bully densities in 2012, mean bully biomass was higher in 2012 (1.00 g m⁻²) than in 2011 (0.04 g m⁻²) because bullies were smaller in 2011.

Common smelt had variable densities, the largest number of which was found in and around the excavated side branch at site 7 edge habitats (up to 14.7 fish 100 m⁻²) below the weir (site 1).

Mean density of rainbow trout in the Ohau Channel was similar in both years (0.27 fish 100 m⁻² in 2011,0.24 fish 100 m⁻² in 2012). Mean biomass of rainbow trout was much greater in 2012 (0.69 g m⁻² in 2011, 11.2 g m⁻² in 2012). Goldfish densities were greater in 2012, partly because goldfish at site 7 were targeted in 2012, and mean biomass was correspondingly greater (0.48 g m⁻² in 2011, 47.7 g m⁻² in 2012). Site 7 had 282 g m⁻² of goldfish biomass in 2012.

Catch per unit effort (CPUE) for common bullies in 2011 was twice that in 2012, reflecting lower densities in 2012. Common smelt CPUE in 2012, however, was 5 times greater than in 2011. Despite the much higher biomass of goldfish in 2012, CPUE was much the same.
The increased goldfish biomass in 2012 arose because of targeted fishing in the excavated side branch, which clearly offers good habitat for goldfish. In 2012, the first shortfin eel encountered in these surveys was caught. The abundance of common bully appears to have a clear trend of reducing abundance since these surveys started in 2007. The cause of this is not apparent, and not accounted for by water clarity expressed as black disk (BD) distance or water conductivity (Table 7). Poor water clarity can reduce the efficiency of electrofishing, but BD was greater in 2012 than in 2011. It is possible that smelt abundance has declined too, but the relatively inefficient sampling resulting from boat electrofishing must be considered. Independent verification is required.

text: Boat electrofishing surveys of fish populations in the Ohau Channel in 2011 and 2012 The aim of the survey was to provide on-going monitoring of the fish communities and abundance in the Ohau Channel, especially fish species that are taonga to Maori (eels, goldfish, and koura). In the current study we present the findings from the fifth and sixth years of sampling (2011 and 2012) in view of previous surveys using boat electrofishing in the Ohau Channel.

We used the University of Waikato’s 4.5 m-long, aluminium-hulled electrofishing boat to catch a total of 399 fish (29.4 kg) from 10 sites in 2011 (2,420 linear m, 9,680 m² area) and 301 fish (12.8 kg) at 11 sites in 2012 (3,625 linear m, 14,500 m² area). Koura and 7 fish species were present in both years, with common bully the most abundant in 2011 and common smelt the most abundant in 2012. Common smelt were more abundant in 2012 (131 fish) than in 2011 (39 fish). Goldfish were most abundant at sites in the lower channel, especially at site 7.

As reflected in total numbers, common bullies had the highest densities of any fish species in 2011 (up to 7.4 fish 100 m⁻²), the majority of which were taken from edge habitats at sites 4, 5 and site 7. In 2012, common bully abundance was much reduced. However, despite the lower bully densities in 2012, mean bully biomass was higher in 2012 (1.00 g m⁻²) than in 2011 (0.04 g m⁻²) because bullies were smaller in 2011.

Common smelt had variable densities, the largest number of which was found in and around the excavated side branch at site 7 edge habitats (up to 14.7 fish 100 m⁻²) below the weir (site 1).

Mean density of rainbow trout in the Ohau Channel was similar in both years (0.27 fish 100 m⁻² in 2011,0.24 fish 100 m⁻² in 2012). Mean biomass of rainbow trout was much greater in 2012 (0.69 g m⁻² in 2011, 11.2 g m⁻² in 2012). Goldfish densities were greater in 2012, partly because goldfish at site 7 were targeted in 2012, and mean biomass was correspondingly greater (0.48 g m⁻² in 2011, 47.7 g m⁻² in 2012). Site 7 had 282 g m⁻² of goldfish biomass in 2012.

Catch per unit effort (CPUE) for common bullies in 2011 was twice that in 2012, reflecting lower densities in 2012. Common smelt CPUE in 2012, however, was 5 times greater than in 2011. Despite the much higher biomass of goldfish in 2012, CPUE was much the same.
The increased goldfish biomass in 2012 arose because of targeted fishing in the excavated side branch, which clearly offers good habitat for goldfish. In 2012, the first shortfin eel encountered in these surveys was caught. The abundance of common bully appears to have a clear trend of reducing abundance since these surveys started in 2007. The cause of this is not apparent, and not accounted for by water clarity expressed as black disk (BD) distance or water conductivity (Table 7). Poor water clarity can reduce the efficiency of electrofishing, but BD was greater in 2012 than in 2011. It is possible that smelt abundance has declined too, but the relatively inefficient sampling resulting from boat electrofishing must be considered. Independent verification is required.

year: 2013