Getting eucalypts into paddocks: Is Whole of Paddock Rehabilitation working?

Abstract

The ongoing loss of paddock trees in agricultural landscapes in south-east Australia must be reversed. Since white settlement more than 95% of box gum grassy woodlands in the region have been cleared to make way for intensive agriculture, with devastating consequences for landscape health, biodiversity, and productivity. Whole of Paddock Rehabilitation (WOPR), an agri-environment scheme run by environmental non-government organisation Greening Australia, seeks to address this by putting trees back into these landscapes at the paddock scale. This project presented in this thesis aimed to assess the success of WOPR, focusing on the presence of eucalypts in WOPR paddocks and farmers’ thoughts on the program to date. The project aimed to articulate the scheme’s theoretical and practical implications, and provide some recommendations from those. This is the first time that mixed-methods research into the WOPR scheme has been done, and the first time that eucalypts in WOPR paddocks have been studied with such precision. Thus, this research is a novel study in an important problem space. Nine study sites were chosen from the southern tablelands of New South Wales. Eight of the sites were seeded between 2009 and 2012, and one in 2008. A complete census of eucalypts was made in every paddock. The fieldwork area comprised nearly 200 hectares and almost 100 kilometres of sown trees. A total of 16 076 individual eucalypts sown by Greening Australia were counted, 41 remnant trees were measured, and 12 farmers from nine properties were interviewed. The average WOPR site in the study was five years old (as of spring 2015), contained 1 786 WOPR eucalypts at a density of 99 per hectare, and had an area of 22 hectares. Distribution of eucalypts within and between the paddocks was highly variable. Eucalypt density was strongly associated with rainfall in the year seeded and belts’ proximity to shelter. The vast majority of eucalypts had a diameter at breast height of ≤ 5cm; grazing history was strongly associated with tree size. There was no correlation between the amount of eucalypt seed sown and the number of eucalypts per kilometre of seeding. Using just seed cost, the average WOPR eucalypt cost $0.76. One future scenario modelled shows that WOPR eucalypts should persist into the future at an ideal density for grazing, and potentially provide habitat for hollow-dependent species from 96 years of age on average. Farmers were unanimously positive about WOPR as a program. Participating farmers were generally pleased with their WOPR paddocks, identified ecosystem and cultural services provided by the paddocks, and held Greening Australia in high regard. They identified knowledge gaps and areas for further research. The paddocks’ condition does not appear to be on a trajectory towards the structure of the conservation reference state presented in the literature, but this thesis argues this is not a cause for particular concern as WOPR paddocks are intended for productive use rather than biodiversity conservation. Due to the high variability of eucalypt density across all sites the key recommendation from this study is to retain the current eucalypt seeding rates until further study can be done on the relationship – or lack thereof – between seeding rate and tree establishment rate. In summary, the results from this study indicate that Whole of Paddock Rehabilitation is returning keystone eucalypts to paddocks, that these trees should persist for at least a century, and that the program is doing this well in the opinion of participating farmers. Show more