New Zealand’s unique biodiversity makes the country vulnerable to invasions from alien species. Our native communities struggle to compete with invasive species, therefore, are left at risk. Estimating Wilding Conifer Cone Numbers from Biometric Measurements, investigates the invasive spread of wilding pines in New Zealand, highlighting Pinus contorta as it is recognised as one of the worst spreaders. Initially planted for erosion control, the species has become a significant ecological threat due to its reproductive behaviours.

The study aims to develop a model for predicting the number of cones produced by untreated contorta pine trees from biometric measurements. Determining cone production can help us to calculate future spread risk. Current methods, such as counting cones using binoculars, are untested on Pinus contorta and likely susceptible to error. The research explores the use of both non-destructive and destructive counting methods. Over multiple summers, data was collected across the South Island to build models to estimate cone production. The objective of the models is to predict the total number of cones produced in the current and future years.

Key findings indicate that the most accurate models for predicting cone numbers incorporate crown area, surrounding vegetation density, and the field season (the year data was collected). The binocular method consistently underestimated cone counts, indicating it is unreliable for successful operational use. Trees in low-density conditions showed exponential increases in cone production as the tree ages, compared to those in high-density environments where cone numbers lacked a notable trend as resources were pushed into vertical growth over reproductive output.

The research suggests biometric models can provide an effective and reliable method to predict cone numbers, aiding in the estimations and management strategies of wilding pine spread in New Zealand. Landowners can use these models to generate more targeted control strategies.