Background
There is increasing scientific consensus that climate change is one of the underlying causes of the prolonged dry and hot conditions that have increased the risk of extreme fire weather in many countries around the world. In December 2019, a bushfire occurred in the Adelaide Hills, South Australia, where 25,000 hectares were burnt, and in vineyards and surrounding areas various degrees of scorching and infrastructure damage occurred. The ability to coordinate and plan recovery after a fire event relies on robust and timely data. The current practice for measuring the scale and distribution of fire damage is to walk or drive the vineyard and score individual vines based on visual observation. The process is time consuming, subjective, or semi-quantitative at best.
Aim
As such, the aims of this study were to (1) Investigate if satellite imagery can rapidly and objectively map fire damage; and (2) Understand the relationship between fire damage and the long-term viability and productivity of damaged vines. It was hypothesised that satellite imagery would correlate with ground truth data and that vine recovery would vary depending on the initial fire damage.
A gain in knowledge in this area will provide growers with a better understanding of the likely effect of fire damage on vine health and productivity to improve vineyard management after a bushfire.
Methods
This study compared the rapid assessment and mapping of fire damage using high-resolution satellite imagery with more traditional ground-based measures.
Results
Correlations between ground visual fire damage assessments and postfire NDVI (-0.347 to -0.084) and VARIgreen (-0.333 to 0.074) satellite imagery were significant but showed no correlation to a weak negative correlation. Canopy growth, vine fertility and starch concentrations were tracked in the two seasons following the fire event to assess vine recovery. Canopy health in the seasons following the fires correlated to the severity of the initial fire damage. Severely damaged vines had reduced canopy growth, were infertile or had very low fertility as well as lower starch concentrations in buds and canes during dormancy, which reduced productivity in the seasons following the bushfire event. In contrast, vines that received minor to moderate damage were able to recover within 1-2 years.
Significance of the study
Tools that rapidly and affordably capture the extent and severity of damage over a large vineyard area will allow producers, government and industry bodies to manage decisions in relation to fire recovery planning, coordination and delivery, improving the efficiency and effectiveness of their response.
However, this is challenging as the varying degrees of fire damage are difficult to quantify and were not imposed by the authors, therefore this type of research is more observational (rather than experimental) in nature. This study allows inference to association rather than causation, and authors acknowledge that there may be other contributing factors that were not apparent. Regardless, the large differences in canopy growth and reproductive development between the different levels of fire damage are believed to be of value and interest to producers and managers as they provide some insights into the recovery process that can be used for vineyard management decision making.
Reference
Collins, C., Ritchie, M., James, A., O’Brien, P., Ma, S., De Bei, R., & Clarke, A. (2022). Grapevine recovery after fire and a first look at rapid damage assessment with satellite imagery: This article is published in cooperation with Terclim 2022 (XIVth International Terroir Congress and 2nd ClimWine Symposium), 3-8 July 2022, Bordeaux, France. OENO One, 56(2), 265–278.
Excerpts of text, without editing, from the original abstract and article were used to create this article summary, as permitted by the following Creative Commons licence: https://creativecommons.org/licenses/by-nc-nd/4.0/
Image credit: https://cluboenologique.com/story/napa-wineries-ask-what-now-as-they-survey-glass-fire-wreckage/
