Mānuka and cattle not quite the honey pot

Abstract

Incorporating productive trees and shrubs into cleared grazing land offers a potential win:win: income from both livestock and tree-crop enterprises, alongside benefits for carbon, biodiversity and landscape function. However, proven silvo-pastoral options in the grazing lands of Australia are limited. Leptospermum plantations to support high value ‘Mānuka’ honey production and livestock grazing are a potential opportunity. However, there is currently little demonstrated plantation success, particularly in more challenging climatic and edaphic regions. We collaborated with an innovative grazing business in southern inland Queensland to implement a replicated trial, which was established in 2021 to assess five Leptospermum varieties and two plant spacings (1 and 2m), along with improved agronomic techniques. Shrub survival, growth and carbon sequestration were recorded for three years.
Despite the agronomic efforts and relatively favourable rainfall conditions, after three years, survival was >50% for only two varieties and shrub growth was slow (53-66cm average height for the best four varieties). Shrub height was substantially impacted by frost each winter. There was no impact of plant spacing, due to the small shrub size reached. Restricted sampling of nectar indicated that two varieties contained medium to high levels of the active ingredient hydroxyacetone (DHA). An indicative Leptospermum shrub height to above-ground carbon biomass relationship was developed for shrubs up to 2m high. Based on our results, establishing a Leptospermum plantation in the southern inland Queensland region appears to have a low likelihood of success for delivering productivity, economic and environmental outcomes.