Jonathan Dash

• Researcher at Scion

Surfaces that describe spatial variation in optimal stand density following final thining (Sopt) are likely to be of considerable use to forest managers. Using a comprehensive series of growth model simulations, the aim of this research was to (i) develop a model of Sopt that maximises volume of large-diameter, small-branched sawlogs (S27) for unpr...

The spread of exotic conifers from commercial plantation forests has significant economic and ecological implications. Accurate methods for invasive conifer detection are required to enable monitoring and guide control. In this research, we combined spectral information from aerial imagery with data from airborne laser scanning (ALS) to develop met...

Research into remote sensing tools for monitoring physiological stress caused by biotic and abiotic factors is critical for maintaining healthy and highly-productive plantation forests. Significant research has focussed on assessing forest health using remotely sensed data from satellites and manned aircraft. Unmanned aerial vehicles (UAVs) may pro...

Discrete airborne laser scanning (ALS) data has emerged as a useful tool for mapping forest leaf area index (LAI). Both empirical and physically-based approaches linking pulse penetration to LAI through gap probability theory have been widely used. We contrasted these approaches using field measurements of LAI (n = 135) acquired in stands of pure P...

Satellite interferometric synthetic aperture radar (InSAR) is emerging as a viable low-cost alternative method to airborne laser scanning (ALS) for forest inventory though little research has examined its efficacy for plantation forests located in temperate regions on steep terrain. InSAR and ALS data were collected from Geraldine Forest which is l...

An extensive forest fire dataset covering plantations in a fire-prone region of South Africa across two decades was used to examine the impact of forest fires on estate value. Catastrophic forest fires are rare events and so conventional statistical methods are not viable for describing their occurrence. We applied methods from an alternative branc...

NASAs Global Ecosystem Dynamics Investigation (GEDI) is collecting space-borne full waveform lidar data with a primary science goal of producing accurate estimates of forest aboveground biomass density (AGBD). This paper presents the development of the models used to create GEDIs footprint-level (~25 m) AGBD (GEDI04_A) product, including a descript...

This study addresses the use of multiple sources of auxiliary data from unmanned aerial vehicles (UAVs) and airborne laser scanning (ALS) data for inference on key biophysical parameters in small forest properties (5–300 ha). We compared the precision of the estimates using plot data alone under a design-based inference with model-based estimates t...

Mapping of tree seedlings is useful for tasks ranging from monitoring natural succession and regeneration to effective silvicultural management. Development of methods that are both accurate and cost-effective is especially important considering the dramatic increase in tree planting that is required globally to mitigate the impacts of climate chan...

Advances in remote sensing combined with the emergence of sophisticated methods for large-scale data analytics from the field of data science provide new methods to model complex interactions in biological systems. Using a data-driven philosophy, insights from experts are used to corroborate the results generated through analytical models instead o...

Wilding conifers, the naturally regenerated scions of exotic conifer species, are a major ecological and economic issue in New Zealand. Hyperspectral imagery could provide a useful means of monitoring the efficacy of wilding control measures but little research has examined this possibility. Data were collected from an experiment, that included thi...

The development and proliferation of unmanned aerial vehicles (UAV) in recent years presents a new data collection opportunity for invasive alien plant (IAP) research. The flexibility and cost‐efficiency of these craft offers a valuable solution where high‐spatial or high‐temporal resolution remotely sensed data are required. In this paper, we revi...

Intensively managed forests are expected to play an increasingly important role in meeting future global demand for wood products. To meet this challenge, a key focus will be on lifting yields from these forests along with economic returns. In this study, we used data from a long-term series of trials that were established in radiata pine (Pinus ra...

Exotic conifers can provide significant ecosystem services, but in some environments, they have become invasive and threaten indigenous ecosystems. In New Zealand, this phenomenon is of considerable concern as the area occupied by invasive exotic trees is large and increasing rapidly. Remote sensing methods offer a potential means of identifying an...

Fine-scale characterisation of forest stands using very high-density aerial lidar data holds considerable potential for improving the accuracy of area-based forest inventories. To realise these gains, new methods of characterising dense aerial point clouds are required. This research presents one potential approach using voxel-based metrics often a...

The application of fertiliser is an important silvicultural practice that can induce significant increases in tree growth. However, as responses to fertilisation vary widely, the accurate identification of infertile stands is critical to ensure that this treatment is applied in a cost-effective manner. Through synthesising literature from a range o...

Phenotyping is the accurate and precise physical description of organisms. Accurate and quantitative phenotyping underpins the delivery of benefits from genetic improvement programs in agriculture. In forest trees, phenotyping at an equivalent precision has been impossible because trees and forests are large, long-lived, and highly variable. These...

The development of methods that can accurately detect physiological stress in forest trees caused by biotic or abiotic factors is vital for ensuring productive forest systems that can meet the demands of the Earth’s population. The emergence of new sensors and platforms presents opportunities to augment traditional practices by combining remotely-s...

Point cloud data derived from stereo satellite imagery has the potential to provide large-scale forest inventory assessment but these methods are known to include higher error than airborne laser scanning (ALS). This study compares the accuracy of forest inventory attributes estimated from high-density ALS (21.1 pulses m −2) point cloud data (PCD)...

There is increasing pressure to raise yields from intensively managed forests in order to improve profitability and to provide for future expected demand for wood products. Deployment of genetically improved tree stocks and control of tree spacing are two means by which forest managers can manipulate total yield, log properties and the economic val...

Final crop stand density is an important determinant of plantation value. A relatively simple model, based on productivity indices, has recently been developed that can spatially optimise final crop stand density Sopt, of the widely planted plantation species Pinus radiata D. Don for stands grown for structural grade timber. When applied to New Zea...

This article summarises recent advances in methods for extracting hydrological features such as channel networks from light detection and ranging (LiDAR) derived terrain data. These techniques have the potential to support forest managers seeking to better plan and monitor compliance with emerging environmental standards like the National Policy St...

Unmanned aerial vehicles (UAVs) have emerged as important and useful platforms for acquiring remotely sensed data, offering the ability to collect imagery and other data with increased spatial and temporal resolution. In the New Zealand and Australian forestry sectors, UAV applications include a range of tasks such as cutover mapping, forest health...

Background An understanding of how plantation productivity varies spatially is important for forest planning, management and projection of future plantation yields and returns. The 300 Index is a volume productivity index developed for Pinus radiata D.Don that has been widely used within New Zealand to assess site productivity. Although the 300 Ind...

This article summarises recent developments in remote sensing technologies that will have, or are already having, a substantial impact on forest management practices. These technologies have the potential to usher in a new error for the forestry sector with the advent of precision forestry. In this article we review forest measurement through laser...

The objective of this study was to compare the utility of combinations of data from airborne laser scanning (ALS), RapidEye satellite imagery and auxiliary environmental data to predict stand structure in a plantation forest. Both parametric and non-parametric modelling techniques that could simultaneously predict a multivariate response were emplo...

Site Index (SI) is one of the main measures of forest productivity used throughout the world. For even-age plantations Site Index is defined as the height of dominant trees at a given reference age. Site Index is normally determined from field measurements and expressed from these measurements at the resolution of the stand. Development of fine res...

In recent years, we have undertaken sequencing and assembly of the conifer mega-genome for radiata pine; a huge 25 Gbase genome with large multi-gene families and an extensive repeatome. This project sits alongside an industry aligned programme to generate and develop SNP genotyping resources for both genomic selection (prediction of future perform...

The objective of this study was to investigate techniques for integrating aerial LiDAR data into the forest yield information systems of a forest management company. Nearest neighbour (k-NN) estimation was identified as a useful approach and a 4 000 ha case study was undertaken to provide insight into the performance of the technique in a commercia...