Vineyards and wildfires — clear management conflicts?

As the northern hemisphere moves into spring, media articles are starting to appear concerning wildfires, which can be a feature of summer in some locations. By wildfires, I mean those that burn in forests, shrublands and grasslands, not those confined to urbanized areas — your house may burn down in a wildfire, but most house fires may also start independently. Some of these new media articles are in the wine literature, and therefore natural fire is a topic worth looking at in this blog.

You see, two decades ago, I spent a lot of my professional working time studying the interaction between wildfires and the vegetation of South-Eastern Australia; and so it is part of my professional experience. Basically, the leaves of the plants have volatile oils that guarantee that the plants will burn every few years; and, in return, the fires provide the conditions that the plants need to turn their seeds into young plants (ie. seed release from the parent and/or germination in the soil). That is, the fire is advantageous, and therefore to be encouraged. This means that the plants themselves must have adaptations to survive each individual fire.

From our perspective, like it or not, conservation of the natural environment may thus require an acceptance of wildfires, in this case. However, the local foresters and agriculturalists are not necessarily impressed. Indeed, the wildfires are often a direct threat to any attempt to make a living out of the non-burning plants nearby. For example, in the USA: “Throughout much of the last century, federal and state land management agencies viewed wildfire as an adversary and sought to suppress fires entirely. The US Forest Service, in particular, regarded wildfire as a threat to timber harvests.” This quote comes from Matthew Wibbenmeyer: Trends and solutions in wildfire management, which provides a good overview of the more recent change in attitude discussed below.

This conflict surprises no-one, because human beings are so often in conflict with their environment (eg. global warming). For our purposes here, one of these conflicted groups is grape-growers; and I will discuss here their attempts to grow grapevines without their plants incinerating.

Obviously, we are not talking about all grape-growers, here. Only some of them have to deal with nearby wildfires, usually in what we scientists call Mediterranean-Type Ecosystems — those with hot dry summers and cool wet winters. This includes southern Europe, western North America, western South America, and south-eastern and south-western Australia (see Delineations of Mediterranean climate in Lodi & the rest of the world).

Now, there are two clear requirements for a wildfire, plus the obvious extra one of an ignition source (which may be natural or entirely artificial). The first main requirement is suitable weather, which is usually “hot and dry”, often over an extended period of time. In Australia, they have roadside signs indicating five increasing possibilities of local fire weather, as shown above. (Note: in the modern world, there is now an extra category: Catastrophic.) When it is Extreme, don’t you even think of throwing a cigarette butt out your car window!

The effect of weather is complex — hot and dry encourages fires, while cool and wet encourages plant growth, which can then burn later (Why historic storms are ‘both a blessing and a curse’ for California's fire season;   How winter’s atmospheric river storms could supercharge California’s wildfire season). In turn, of course, wildfires can change the local weather patterns (Extreme wildfires make their own weather); and they can affect, for example, future drought conditions. Everything ties together!

The second main requirement for a wildfire is a minimum amount of burnable vegetation, which we call the “fuel load”. Obviously, the more fuel there is, in terms of both area covered and amount of plant material per unit area, then the bigger the fire will be. Most wildfires start off small, especially if the ignition source is artificial; but they can spread pretty damn fast. (Indeed, faster than you can run, as many people have learned to their cost.)

Fuel management is a complex topic, which I will not go into here. An important point, though, is who should be doing the managing, and what is the goal of the management (for example: conservation within native vegetation versus property protection nearby). You can guess what parts of the wine industry think (Leave fire management to farmers, says Aussie wine boss); but other organizations are involved as well (Napa County works on fire hazard road standards). Things can get worse either way (UC Davis Study: California wildfire growing stronger as fuel management practices adapt).

The effect of the fire on the burnt area is obvious to all observers; and, so, those landholders in nearby areas are quite correctly concerned about how far any given fire will spread. After all, they don’t want their cash crop incinerated (Vineyard recovery from fire damage), or their buildings burnt (Fire destroys Hunter Valley’s Tamburlaine Organic Wines function venue;  Fire destroys outbuilding at Napa County winery). As an example of the possible magnitude:

From 2017 to 2020, wildfires burned through more than half of Napa County's land area and destroyed more than 1,500 structures. The valley’s fire risk has had major repercussions for wineries — and all North Bay landowners.

However, there are also other potential fire effects on the surrounding areas (ie. the non-burnt part), notably smoke, and heat. Both of these are of serious concern to grape-growers, for example. Smoke is becoming a topic of more interest (How much wildfire smoke can California wine grapes sustain? A new bill aims to find out); and clearly there needs to be a management strategy (A clear objective for smoke research).

Obviously, there are only three possible management strategies for unwanted fires:

avoid  /  mitigate  /  ignore

Over the decades, the first one has been shown to be basically impossible in Mediterranean-Type Climates (this is what a lot of the previous scientific research has been about). The third one is easy to do, but will obviously not be successful in the long term (and farmers are usually more pro-active than this!). That leaves the second option.* There are many aspects to this (Napa Valley to host wildfire resilience summit), and the planning needs to take into account fire mitigation as well as ecosystem restoration. This also includes appropriate insurance, of course (Napa Valley wineries, seeking insurance relief, show steps to lessen wildfire risks;  Farm Bureau continues advocacy on Napa Valley wildfire issues). Whole books have been written about this topic; and there is now a UN-REDD program for Fire Management (inspired by the interaction between climate change and increasing propensity of fires).

Sadly, dealing with wildfires is not the only thing that a grape-grower needs to deal with:  California farmworkers cope with wildfire smoke, pesticides, roaches and rodents, survey says. It is much easier to drink wine than to be a part of making it! (Especially in Argentina, just at the moment.)

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* A classic example is what in Australia is called a “fire-block” — an open piece of land around something valuable, which can act to stop the progress of an oncoming wildfire. Well, one such piece of land in the Clare Valley (South Australia) is now home to the Fireblock vineyard. This is of interest to me, personally, because it is owned by Bill Ireland (and his wife Noelene), who is the person who first taught me to appreciate wine, when he used to hold free tastings of new wines in his Summer Hill Wine Shop (in Sydney) on thursday nights (late-night shopping night). The Fireblock wines are not exported to many places, but Sweden is one of them!