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.
The video presents my voice-over commentary and the PowerPoint slides. Unfortunately, it doesn’t include the Google Earth flyover that we showed on the day, as we couldn’t record a high quality screen image of the flyover. [Note: the picture quality in the video is much better than it looks in the YouTube screen grab above].
If the embedded video does not appear on your mobile device, you can watch it at YouTube, at this link. We hope you enjoy the talk. If nothing else, we think you’ll be surprised at how widespread natural regeneration is in many regions.
Very nice presentation. Across SE Australia — do the positive forces regeneration now outweigh the negative ones of lack of regeneration? This would be very nice! But I have to admit, it’s not what I observed about five years ago when looking for regeneration in the Upper Lachlan catchment in NSW. Your examples are compelling, nice work!
Hi Joern, thanks for sending a comment, I’m glad you enjoyed the video. As I see it, the amount of vegetation change (or regeneration) will depend on the amount of land use change in recent decades. Where land use has remained relatively stable then we’d expect little opportunity for new regeneration, as you found in the Lachlan, and as I described in an earlier blog on old paddock trees: https://ianluntresearch.wordpress.com/2013/03/13/the-candles-of-dunkeld-2/. By contrast, where there’s been lots of land use change (especially retirement of grazing and no cropping), then more opportunities for regeneration arise. In the regions you worked in, I’d expect little change to have occurred – or certainly far less change than in central Victoria – since grazing and cropping remains the dominant land use.
I think that one of the major points from our work is that we’ve often taken the declining paddock tree syndrome as being the primary story for regional Australia. This syndrome is a huge problem in many regions. But in other regions a very different phenomenon is occurring, with abundant regeneration. To be honest I find it really surprising that the abundant regeneration hasn’t been pointed out a lot more before, as it’s not hard to find. For some reason, we haven’t been looking for it. There’s a wonderful contrast between the biodiversity gains that may occur in new regrowth here, and the declines that have been described from Europe by many posts on your web site: http://ideas4sustainability.wordpress.com/. Thanks again, and best wishes, Ian
Very good and quite inspiring! Indeed, in the places where I had worked (virtually never in VIC) things may be far less positive. But your “other side of the coin” gives plenty of valuable food for thought. Cheers — J.
BTW Joern, I suspect that if someone compared the old air photos with recent ones around Canberra, where you used to live, they’d find lots of natural regeneration there too, for the same reasons as in Vic. I don’t have the old air photos but the veg patterns on the current photos closely resemble those in the regrowth areas in Victoria, especially around the Gundaroo region. Cheers Ian
Great post/presentation and your observations re southern parts of the Strathbogie Ranges seem (anecdotally) valid for much of the freehold land across this region. The 1940-60’s aerial photomosaics available for much of Victoria are certainly valuable documents. Sorry I missed the original presentation in Ballarat – have heard lots of positive feedback.
Hi Bert, thanks very much for your comment, I’m glad you liked it. I might do another post in the future with more pics of natural regeneration around the Strathbogies and surrounds as there are some really interesting changes in some areas. Best wishes Ian
Thanks for posting this presentation delivered by Lisa Smallbone, Alison Matthews and yourself. It is an encouraging pattern to see fragmented landscapes being linked through natural regeneration. I state this for a few reasons. Foremost, natural regeneration takes less resources and is more sustainable than revegetation and seeding; secondly this pattern has been made possible due to a shift in our thinking and use of land; and finally – this pattern will hopefully begin to address some of the declines in native fauna abundance and diversity by increasing habitat and dispersal opportunities.
From the presentation I see that this pattern is not isolated and is wide spread across Victorian landscapes. Are there many examples that you are aware of where landscapes with scattered trees have passed a threshold and do not conform to this pattern?
I’m sure the autoecology of shrub species may disrupt the generalisation of shrubs dominating grasslands then within ~10 years being taken over by tree species. The example of Acacia paradoxa at Inverleigh Nature Reserve appears to contrast this grass/shrub/tree succession.
Or do you think that given time, tree domination would occur. It would have to be time long enough to exhaust the seed viability (and no disturbance to add new seed to the bank).
Is Inverleigh Nature Reserve a special case with the shrub species (A. paradoxa) increasing from 3% in 1947 to 42% in 2002, and still increasing? Will the tree canopy take over in the same pattern or is this a special case due to the autoecology of A. paradoxa?
I am interested to know if the pattern your co-authors and yourself present is the norm, or are there many landscapes stuck in a shrub-warp? I want to remain optimistic that there is a general pattern of resilience and re-connectivity! What are your thoughts?
Hi Rus, thanks for a great comment and question. As you suggest, I’m sure that tree-shrub dynamics will differ greatly according to the ecology of the shrubs. The picture of the bottom of this post is of a large burgan stand. Burgan grows over 3 m tall and I suspect many plants would live for 50 years or more (although I have no data on this). I would imagine that these stands would prevent establishment by eucalypts for the life of the shrubs, unless they were burnt (or otherwise disturbed) and trees could establish after the fire perhaps.
Dense stands of Hedge wattle (Acacia paradoxa) are likely to resist tree establishment for long periods too. ( I wrote an earlier blog on hedge wattle at Inverleigh last year –
https://ianluntresearch.wordpress.com/2012/04/26/sieving-the-seeds-of-the-future/ ). Again I don’t have any data (and I don’t think any exists) but I would imagine that trees would probably have to establish after fires if they were to establish in dense hedge wattle stands.
More broadly, you make an excellent point that, in some (perhaps many?) cases, shrub stands may persist for much longer than occurs in the cassinia – grey box systems that I talked about in the video. On one hand, I can appreciate the desire to promote tree cover. On the other hand, I think we need to learn to live with many persistent shrub stands, and to promote the ecological values they have. They can provide great habitat for birds that like dense under-stories, which is certainly valuable in areas that once were, and are now surrounded by, cleared pasture. Thanks again, best wishes Ian
Thanks for the post and presentation, Ian. I’d like to know your view on the role of exotic plants as part of biodiversity and habitat I also wonder if enough research is being done on this subject. I’m prompted to raise this point after hearing that African Boxthorn is being cleared from beaches where it has provided protection for little penguins from cats and foxes. The African Boxthorn is being replaced by wooden nesting boxes which will presumably rot after a few years.
Similarly in my own patch in central Victoria I can’t help but note that each time a local Landcare group clear a patch of blackberry, they are destroying a habitat that provides safe nesting sites for small birds.
To what extent should we accept exotics and value those that have habitat value?
Hi Mel, that’s a big question. There’s no doubt that some exotics can provide important habitat for native birds and animals, particularly in degraded habitats. So decisions about removing exotics can involve trade-offs with habitat loss. I guess there are two different issues involved. First, how much do we value the current presence (or absence) of the exotic versus the habitat it provides? Secondly, what is the risk that the exotic, if not removed, would increase or spread further in the future, and what implications would this have on the things we value? The second argument is often invoked to justify removing exotics (although the degree of risk is rarely described explicitly).
I don’t have a ready answer to your question I’m afraid, as there are lots of different values involved, and different people value things differently. I’m sure in another 100 years, people will look back at our attitudes towards exotics with some bemusement, but who knows what beliefs and attitudes will replace our current ones? If nothing more, it’s important to be aware of potential positive impacts of exotics before removing them. Sorry I can’t give a more compelling response. Best wishes Ian
Ian I hope and want to believe your good presentation is right! It reminded me of an old incident.
Many decades ago, when I was still at the Aust Heritage Comm I had a phone call one day from then PM Malcolm Fraser. He wanted to know whether some of his constituents in Wannon could get a Grant to replant E camaldulensis which happened to be the logo of Wannon Shire. As one does with a PM I enthused about what a good idea of course. But then I gently tried to steer him towards encouraging them to simply fence off paddock areas around old trees pointing out that this spp was one of the easiest to get natural recruiting from as long as the “ 4 legged vacuum cleaners” (to use Commissioner Vin Serventy of the AHC best phrase) were kept off them!
I think in the end he agreed and we never got an application! Will read your future posts with interest.
Hello Max, thank you very much for your comment, I’m glad you liked the video. Different processes are going on in different regions, and there hasn’t been very much regeneration of paddock trees in lots of regions still. I wrote another blog earlier this year about old red gums in the Wannon region, which may interest you: https://ianluntecology.com/2013/03/13/the-candles-of-dunkeld-2/ I look forward to the day when the PM asks for advice by sending in a comment on my blog! Thanks again, best wishes Ian
Hi Ian, Sorry for my belated response this is a nice presentation and great to see some of the research! I was particularly keen because you are working in my local area and have very neatly put some of the processes together into a plausible and positive narrative. This is well done and matches substantially my own observations and experience with our own regenerating land in the Eppalock area. I found the analysis regarding the bird composition data really interesting particularly w.r.t. the general broader suitability of regrowth areas. Having documented the life-cycles of many hundreds of box iron-bark invertebrates there is a nice logical and biologically feasible correlation between plant diversity and invertebrate diversity and likely productivity in landscapes. How many of your birds studied were insectivores and does this group dominate in describing the variance between the veg systems? I am really interested in your thoughts on the ongoing journey of these regrowth landscapes/areas. You mention that these tend to become tree dominated. My local observation would be that the regrowth areas tend to be “tree choked” with stem densities often an order above the “natural situation”. in these settings competition effects significantly depress the understory while in mature forest (what little remains) there appears more balance with less but larger trees and more herb and shrub. On our own land we can see the original density of trees (from the stumps) and have been actively thinning regenerating trees to match this. After 15 years we now have trees of equal or greater height than those in the 50+ year old remnants in the state forest nearby. Some trunks are approaching 40-50cm in diameter and our understory composition (with small assistance through planting “nursery specimens”) is now more diverse than most of the remnants on public land. Is the role of the more recent regrowth areas to support birds etc accentuated because of the more advanced trajectory of the older “remnants” towards a tree dense phase and these likely to take a long time to settle back to a more sustained, resilient and diverse system? The question playing out on our land is what happens when you combine an essentially passive approach to regeneration with a bit of ecological tree thinning? Our hope is that we can accelerate the natural trajectory to an early more stable and diverse outcome. Regards Steve Williams
Hi Steve, thanks for your great thoughts. It’s great to hear you are collecting good data on invertebrates as that’s a big hole in our understanding of these (and most) systems. Many of the birds that increased in the shrubby regrowth were small insectivores. I will email you a copy of the paper that Lisa Smallbone published so you can see the list. Chris Jones and colleagues at Melbourne Uni have just published a new paper on the effects of dense regrowth and thinning on understory plants, which is really interesting. You can read a summary at Chris’ blog here – https://csjonesresearch.wordpress.com/2015/01/05/new-paper-dense-stands-and-thinning/ . I’ll send you a copy of this too. Keep up your great work, best wishes Ian