Like patch mosaic burning? I bet you know someone who does. The concept – like corridors and connectivity – is popular with land managers and the public, and often adopted with ‘mucho gusto’.
The theory that underpins patch mosaic burning is simple. We light patchy burns or burn small areas to create a mosaic of zones, each with a different fire history. The mosaic of burnt and unburnt patches will, the argument goes, increase species diversity (or the abundance of some species) across a landscape, reserve or remnant.
Intuitively, this makes sense. At one level, it’s a simple strategy to spread risk; it says ‘don’t put all your eggs in one basket’.
Evidence, what evidence?
Unfortunately, the scientific evidence that mosaic burning promotes biodiversity is – to put it politely – equivocal and contested. Indeed, a recent global review of how vertebrates responded to fire mosaics found ‘little support for the patch mosaic burn theory’ at all.
This gulf between evidence and acceptance makes patch mosaic burning a great topic for a series of blog posts. In coming months, we’ll explore in more detail the tantalizing idea that ‘pyrodiversity begets biodiversity’.
A warning for future posts. If you view fire management in black and white, good versus bad, terms, I suggest you tune out now. There are no simple solutions to the complex issues surrounding burning and biodiversity. Consequently, the posts can’t and won’t present definitive statements about how ecosystems should (or should not) be burnt. The goal is to explore concepts, not prescribe outcomes.
What is a mosaic?
One of the challenges to patch mosaic burning is – to quote one review – All fires create mosaics of some kind. This makes it difficult to ‘operationalize’ mosaic burning. What size, shape and number of patches should we burn? How should burns be arranged over space and time? At any even simpler level, how do we tell if something is or isn’t a patch burn mosaic?
Let’s kick off the series with an animation. I’m happy to call the video below a comic, but you may recognize it as a comical Socratic dialogue. It asks a deceptively simple question: what is a patch burn mosaic (or a ‘PBM’ for short)?
The animation is a gif file which loops over and over. You can open a larger, sharper version in a separate web page by clicking on the image. To re-start it from the beginning, just refresh your web page.
Want to re-read the final messages without watching the whole video again? Watch this version. The animation is also available as a YouTube video (instead of an animated gif file), which can be started, stopped and paused at will.
A mighty mosaic
The animation includes photos of patch mosaic burning in the Great Sandy Desert region, in north-west Australia. You can explore these striking fire patterns by zooming and panning inside the Google Map below.
If you can’t see the embedded Google Map on your browser or device, you can visit the area by clicking this link. Enjoy.
The following papers provide a great introduction to the complexities of managing fire mosaics for biodiversity.
Driscoll DA & colleagues (2010) Fire management for biodiversity conservation: Key research questions and our capacity to answer them. Biological Conservation 143, 1928-1939. [Full text article available for free here].
Parr CL & Andersen AN (2006) Patch mosaic burning for biodiversity conservation: a critique of the pyrodiversity paradigm. Conservation Biology 20, 1610-1619. [Full text article available for free here].