Ooooh, I'm so excited to get to blog about this book chapter, because it is the book chapter that introduces you to one of my new favourite science places - the Avon Critical Zone Observatory! Situated on the UWA Farm, we've spent the past few years putting some really cool infrastructure in place- we've got flux towers, and borewells and permanent ERT transects, and soil moisture sensors, and recently some really fun collaborations with Exige and EcoDetection to try out exciting new technologies. It's a very exciting place, and we'd love to invite more researchers to come and learn with our facilities!
A critical zone observatory is a place where we can get insights into how water, energy, carbon and other solutes move between the atmosphere, the soils and the hydrosphere - a vertical continuum called the critical zone. That's what all that cool infrastructure helps us do.
But, why build an Critical Zone Observatory (CZO) in the Avon River Catchment? Well, most other CZOs are in the northern hemisphere which has a really different geological history, and often with shallower soil profiles than the deep, ancient, heavily weathered landscapes that we have in Australia - and which are exemplified by the Avon CZO.
The Avon CZO is about 1.5 hours drive east of Perth, so it's an easy day trip (but definitely a day trip). It's in the western grainbelt of WA, an area of fairly high rainfall (by WA grainbelt standards, 450 mm/year or thereabouts), and, consequently, more topographic relief than in the drier landscapes further east.
Most of the Avon CZO is formed from weathering and fluvial/aeolian reworking of an ancient lateritic landscape, so it's got lots of lovely rolling hills that are more-or-less good for farming (see the ERT1 and ERT2 transects below). But it also has a few places where you can see the ancient landscape still in place - lateritic hills. And these spots let us look through time and right through the critical zone. Here are photos Matthias Leopold took to illustrate this point.
We can also look through the critical zone with geophysics (and in a post soon I'll blog about Jessie Weller's paper on geophysics of these hills in more detail) - ERT3 in the figure below shows us the little bit of left-over laterite on Fox Hill, and how it overlies clay formed by weathering of the laterite, and then saprolite over bedrock. It corresponds to the same profile shown with photos above. What BLOWS MY MIND about these hills is that we believe they are the former streambeds - where the laterite formed thickest and so persisted for the longest - today's hills are the past's valley bottoms? When you stand there and look at these little hills and imagine the past - it just brings home how enormous the amount of material that has been moved and exported over the years was.
This chapter also helps show some of the differences in ecosystem function that occur when changing from native vegetation to farming. By comparing flux data from Avon CZO to the native wandoo woodland nearby at Boyagin we can clearly see the reductions in evaporation that are associated with changing from perennial deep rooted vegetation to annual cropping.
We have so much cool new data coming in from this site and honestly we probably need 3 PhD students and many people writing new grants to work here to get the most out of it! So check out this fun book chapter, and come work with us at Avon CZO!
(PS - I know you may not be able to get to the chapter if your insitution isn't signed up for it. Feel free to drop me an email if you'd like a copy, and we'll try to get an author's approved version available on the UWA Research Repository soon).
Comments