Want to re-connect fragmented landscapes? Where would you start? With natural regeneration of course.
Natural regeneration of native trees and shrubs is abundant in many regions, where it provides valuable habitat and linkages between patches of native vegetation. Last week I gave a talk at the Biodiversity Across The Borders conference in Ballarat in a session on landscape connectivity, on behalf of my co-authors Lisa Smallbone and Alison Matthews. Our talk covered four topics.
Why do we get extensive natural regeneration in some regions?
Where do we find lots of natural regeneration in Victoria?
How valuable is natural regeneration for birds?
How can we incorporate natural regeneration in connectivity planning?
If you didn’t get to last week’s conference, you can now watch the video of the talk, courtesy of YouTube.
Imagine you bought a cleared paddock, removed the stock and, for 40 years, you watched the trees and shrubs regenerate. All looked wonderful except that large rings of bare, scalded soil appeared. The large, bare Dirt Rings could be seen on air photos, as shown in yellow above.
How did these strange patterns appear? This is the question I posed in my last blog, and the quiz triggered lots of thoughtful suggestions. This week we solve the Mystery of the Dirt Rings. But first, let’s go back in time to see how the landscape evolved over the past 150 years.
In the mid-1800s, when Europeans first settled the region, it supported a forest or woodland dominated by large Grey Box trees (Eucalyptus microcarpa). In the late-1800s, the paddock trees were ring-barked and cleared to create farming land.
Which is all very well, provided we all agree on what’s good, let alone better. Last week’s blog contained a poll that asked: If you wanted to compare changes in vegetation condition at a site, based on two surveys – the second undertaken many years after the first – should both surveys be done in similar climatic conditions? If the first survey was in a severe drought, should the second also be done in a drought? If you haven’t yet voted, please do, as the poll is open for another couple of weeks.
Based on the votes so far, if I was a tabloid journalist, I’d assert that, voters are deeply divided over this polarizing issue. Continue reading →
Doctors Swamp in 1945. The left-hand photo is the ‘untouched-up’ original. I’ve removed the worst of the blemishes from the right-hand photo. Click on the image to see a larger version.
This month’s post is the second of the ‘Growback’ blogs, which show examples of natural regeneration across Victoria, by comparing air photos from the 1940s with recent images from Google Earth.
This week’s Growback comes from a wetland near Murchison in central Victoria called Doctor’s Swamp. The reserve contains Grey Box (Eucalyptusmicrocarpa) woodland on high ground in the west and an intermittent wetland dominated by River Red Gum (Eucalyptuscamaldulensis) in the east. Continue reading →
The British ecologist, Alexander Watt. Photo source: Wikipedia.
It’s sunny, it’s Sunday, and I’m writing a blog. How sad is that? Fortunately it’s not too bad as I’ve spent a couple of weeks in the field soaking up vitamin D. In lieu of an armchair ecology blog, I thought I’d share some natural history observations from last week’s fieldwork…
Ecologists often focus on the incredibly important process of recruitment. But it’s equally important to understand the slower processes of plant senescence and mortality. What happens when dominant plants get old? Do they re-sprout continually and maintain their dominance? Or do they die and create big, open gaps? If gaps are created, do new seedlings establish, or do other species take over? Continue reading →
I had a fantastic day in the field last week: beautiful weather, great company and lots to see and learn. PhD student, Lisa Smallbone, took her supervisory team, Alison Matthews, John Morgan and I, to visit her field sites. Lisa is studying how birds use patches of native trees and shrubs that regenerate on retired agricultural land. For me a highlight was chatting about the complexities that emerge when we use chronosequences to study long-term ecosystem dynamics.
Everyone wants to know how ecosystems will change in the future. Unfortunately, few of us live long enough to see the end result, so ecologists often cut to the chase by using chronosequences. The word ‘chrono’ is Greek for time (hence ‘chronology’). In a chronosequence, we select a series of sites that differ in age – some old, some middling, some young – and we compare attributes (such as structure, function or composition) between these sites to infer how ecosystems change as they gets older.
Another name for this approach is ‘space-for-time substitution’. We’d prefer to document changes in selected sites over time, but we can’t wait that long, so instead we compare patterns across space, by sampling many sites at just one point in time.
The assumption that underlies this approach is that the only thing that differs between sample sites is their age. All sites are assumed to have been the same initially, and to have experienced the same disturbances and conditions thereafter.
This assumption is the Achilles heel of chronosequence studies.
Climate change presents huge challenges for nature conservation. One important way to save species as climate change worsens is to maximize linkages or ‘connectivity’ between natural ecosystems. Initiatives such as Gondwana Link, the Great Eastern Ranges Initiative (or Alps to Atherton) and Yellowstone to Yukon aim to re-connect fragmented landscapes across enormous areas.