Assessing the Environmental Characteristics of the Margaret River Wine Region, Australia

Abstract

Six sub-regions of the Margaret River Geographical Indication were proposed in 1999 in an attempt to characterize local variations in grape-growing conditions. Detailed environmental data has since been produced and this article aims at reassessing the proposed sub-regions by means of a GIS-based spatial analysis of the new datasets. Topography, climate, and a variety of soil parameters were reviewed, and a relevant set submitted to an unsupervised isocluster classification to determine the natural clustering of environmental parameters. The analysis shows that the initial sub-regions do not consistently respect climate patterns and soil type distribution. It is proposed to distinguish twelve natural units by considering temperature and rainfall gradients as well as the presence of the Dunsborough Fault system which appears to have a significant control on soil distribution. This study also shows that average growing season temperatures have gained +0.2°C across the peninsula from 1961–2000 to 2001–2015.

Underpinning terroir with data: a quantitative analysis of biophysical variation in the Margaret River region of Western Australia

“…Thus, and following the principle of parsimony, Figure 5c arguably offers the most appropriate integration of soil and climate factors; including MJT in addition to GDD (not shown) did not improve or otherwise affect the within‐region discrimination. Of note, and in contrast to previous attempts at subregionalising the Margaret River GI, whilst the present analysis does support possible delineation of the northernmost of the subregions proposed by Gladstones (1999) and Lacorde (2019), the other subregions identified in these previous studies are difficult to discern from this present analysis (Figure 5).…”

“…However, over the top of his initially data-driven approach which identified eight 'isoclusters', he imposed a heuristic incorporation of 'land systems' delineated principally on the basis of major geological and topographical features, such as the Dunsborough Fault, to propose 12 'natural units' within the GI. A key difference between the present analysis and the 'isocluster' analysis of Lacorde (2019) was that both elevation and topographical indices derived from it (slope, aspect) were included in the latter. Here, the approach followed was to use elevation as an explanatory variable to assist with cluster interpretation, as has proven useful in studies of withinvineyard variation (e.g.…”

“…A conceptual plan for viticultural sub‐regions of Margaret River, unpublished report to the Margaret River Wine Association, 1999) had proposed six subregions in the Margaret River GI, the cluster analysis was run for two to six clusters. Where the CCC initially identified the optimum number of clusters as six, the clustering was expanded to up to 12 clusters on the basis of Lacorde's (2019) identification of 12 ‘natural units’ within the GI and the CCC again used to select the optimum number in the 2–12 range. All cluster analyses were conducted twice; once on a whole‐of‐region basis (c.f.…”

Underpinning terroir with data: on what grounds might subregionalisation of the Barossa Zone geographical indication be justified?

“…Vaudour et al 1998, 2010, Jones et al 2004, Carey et al 2009, Bonfante et al 2011, 2018, Fraga et al 2017). These different results led to a different recommended basis for exploring within‐GI wine sensory and chemical differences than one offered on the basis of a ‘whole‐of‐region’ analysis (Lacorde 2019, Bramley and Gardiner 2021). Following our preliminary analysis of biophysical variation in the Barossa (Bramley et al 2020), it was of interest to explore this land use issue in a revised analysis given that only approximately 10% of the land in the Barossa GI is under vine.…”

Making sense of a sense of place: precision viticulture approaches to the analysis of terroir at different scales

“…Despite these advances, with few exceptions (e.g. Fraga et al, 2017;Lacorde, 2019), recent terroir research has remained reliant on heuristic opinion and conformity to previously defined terroir units (Carey et al, 2009;Vaudour et al, 2010;Bonfante et al, 2011;Bonfante et al, 2018), rather than employing purely data-driven approaches. As a consequence, the approach has tended to be one of seeking to validate terroir zones defined historically through an appellation or geographical indication system, rather than using the new methods or, in many places, new data at much higher resolution than was previously available, as a basis for identifying what zoning might be justified.…”