High-altitude ecology

28 08 2014
A constant hazard in the Tibetan Plateau - yakjam

A constant hazard in the Tibetan Plateau – yakjam

I’ve been out of the social-media loop for a few weeks, hence the abnormally long interval since my last post. As you might recall, I’ve been travelling overseas and most recently blogged from Monterey, California where I was attending a symposium on invasion genetics.

The next phase of my travels couldn’t have been more different.

The reason I couldn’t access the blog was because I was well behind the Great Firewall of China. I was, in fact, in the Tibetan region of Gansu and Sichuan Provinces in western China for most of the last 10 days. While I’ve travelled to China many times before, this was by far the most evocative, interesting and unique experience I’ve ever had in this country. Reflecting on the past 10 days while waiting in Hong Kong for my flight back to Australia, I am still reeling a little from what I saw.

Top bloke: Jiajia Liu of Fudan University

Top bloke: Jiajia Liu of Fudan University

What the hell was I doing at 3500-4000 m elevation on the Tibetan Plateau? Good question. I have been most fortunate to be included in a crack team of Chinese ecologists who have designed and implemented a most impressive set of experiments in plant community ecology. The team, led by Professor Shurong Zhou and Dr. Jiajia Lui of Fudan University, has been working relentlessly to put together some of the sexiest plant ecology experiments going in China.

Having now so far published two papers from the some of the experiments (see here and here), my Chinese colleagues thought it was high time I visited the famous site. Situated at 3500 m in the Tibetan region of Gansu Province in western China, the Lanzhou University research station Azi Shi Yan Zhan is about a 20-hectare area of meadow fenced off from the grazing of the ubiquitous domestic yaks herded by the local Tibetans. If that sounds pretty exotic, let me assure you that it is. Read the rest of this entry »

South Australia’s tattered environmental remains

16 04 2014
State budget percentage expenditures for health, education and environment

South Australia State budget percentage expenditures for health, education and environment

Yesterday I gave the second keynote address at the South Australia Natural Resource Management (NRM) Science Conference at the University of Adelaide (see also a brief synopsis of Day 1 here). Unfortunately, I’m missing today’s talks because of an acute case of man cold, but at least I can stay at home and work while sipping cups of hot tea.

Many people came up afterwards and congratulated me for “being brave enough to tell the truth”, which both encouraged and distressed me – I am encouraged by the positive feedback, but distressed by the lack of action on the part of our natural resource management leaders.

The simple truth is that South Australia’s biodiversity and ecosystems are in shambles, yet few seem to appreciate this.

So for the benefit of those who couldn’t attend, I’ve uploaded the podcast of my slideshow for general viewing here. I’ve also highlighted some key points from the talk below: Read the rest of this entry »

More species = more resilience

8 01 2014

reef fishWhile still ostensibly ‘on leave’ (side note: Does any scientist really ever take a proper holiday? Perhaps a subject for a future blog post), I cannot resist the temptation to blog about our lab’s latest paper that just came online today. In particular, I am particularly proud of Dr Camille Mellin, lead author of the study and all-round kick-arse quantitative ecologist, who has outdone herself on this one.

Today’s subject is one I’ve touched on before, but to my knowledge, the relationship between ‘diversity’ (simply put, ‘more species’) and ecosystem resilience (i.e., resisting extinction) has never been demonstrated so elegantly. Not only is the study elegant (admission: I am a co-author and therefore my opinion is likely to be biased toward the positive), it demonstrates the biodiversity-stability hypothesis in a natural setting (not experimental) over a range of thousands of kilometres. Finally, there’s an interesting little twist at the end demonstrating yet again that ecology is more complex than rocket science.

Despite a legacy of debate, the so-called diversity-stability hypothesis is now a widely used rule of thumb, and its even implicit in most conservation planning tools (i.e., set aside areas with more species because we assume more is better). Why should ‘more’ be ‘better’? Well, when a lot of species are interacting and competing in an ecosystem, the ‘average’ interactions that any one species experiences are likely to be weaker than in a simpler, less diverse system. When there are a lot of different niches occupied by different species, we also expect different responses to environmental fluctuations among the community, meaning that some species inherently do better than others depending on the specific disturbance. Species-rich systems also tend to have more of what we call ‘functional redundancy‘, meaning that if one species providing an essential ecosystem function (e.g., like predation) goes extinct, there’s another, similar species ready to take its place. Read the rest of this entry »

Fast-lane mesopredators

29 07 2013

Another post from Alejandro Frid (a modified excerpt from a chapter of his forthcoming book).

I fall in love easy. Must be my Latino upbringing. Whatever it is, I have no choice on the matter. So for five years and counting, I have been passionate about lingcod (Ophiodon elongatus) and rockfish (Sebastes spp.), upper- and mid-level predatory fishes on rocky reefs of the Northeast Pacific.

Lingcod are beautiful and fierce. Rockfish are cosmic. Both taste mighty good and—surprise, surprise—have been overfished to smithereens throughout much of their range. Howe Sound, my field site near Vancouver, British Columbia, is no exception, although new protective legislation might be starting to give them some slack.

Our dive surveys1 and earlier studies, in combination, have pieced together a story of ecosystem change. In the Howe Sound of today, lingcod rarely exceed body lengths of 80 cm. But up to 30 years ago, when overfishing had yet to inflict the full extent of its current damage, lingcod with lengths of 90 to 100 cm had been common in the area. There is nothing unique about this; most fisheries target the biggest individuals, ultimately reducing maximum body size within each species of predatory fish.

As predators shrink, the vibrant tension of predation risk slips away. The mechanism of change has a lot to do with mouth size. Predatory fishes swallow prey whole, usually head or tail first, so it is impossible for them to eat prey bigger than the width and height of their open jaws. And bigger fishes have bigger jaws, which makes them capable not only of consuming larger prey, but also of scaring bigger prey into using antipredator behaviours, such as hiding in rocky crevices. As predators shrink, big prey enter a size refuge and only small prey remain at risk, which can alter trophic cascades and other indirect species interactions. Read the rest of this entry »

Crying ‘wolf’ overlooks the foxes: challenging ‘planetary tipping points’

28 02 2013

tipping pointToday, a paper by my colleague, Barry Brook, appeared online in Trends in Ecology and Evolution. It’s bound to turn a few heads.

Let’s not get distracted by the title of the post, or the potential for a false controversy. It’s important to be clear that the planet is indeed ill, and it’s largely due to us. Species are going extinct faster than the would have otherwise. The planet’s climate system is being severely disrupted, so is the carbon cycle. Ecosystem services are on the decline.

But – and it’s a big ‘but’ – we have to be wary of claiming the end of the world as we know it or people will shut down and continue blindly with their growth and consumption obsession. We as scientists also have to be extremely careful not to pull concepts and numbers out of our bums without empirical support.

Specifically, I’m referring to the latest ‘craze’ in environmental science writing – the idea of ‘planetary tipping points‘ and the related ‘planetary boundaries‘. It’s really the stuff of Hollywood disaster blockbusters – the world suddenly shifts into a new ‘state’ where some major aspect of how the world functions does an immediate about-face. Read the rest of this entry »

No need for disease

7 01 2013

dead or alive thylacineIt’s human nature to abhor admitting an error, and I’d wager that it’s even harder for the average person (psycho- and sociopaths perhaps excepted) to admit being a bastard responsible for the demise of someone, or something else. Examples abound. Think of much of society’s unwillingness to accept responsibility for global climate disruption (how could my trips to work and occasional holiday flight be killing people on the other side of the planet?). Or, how about fishers refusing to believe that they could be responsible for reductions in fish stocks? After all, killing fish couldn’t possibly …er, kill fish? Another one is that bastion of reverse racism maintaining that ancient or traditionally living peoples (‘noble savages’) could never have wiped out other species.

If you’re a rational person driven by evidence rather than hearsay, vested interest or faith, then the above examples probably sound ridiculous. But rest assured, millions of people adhere to these points of view because of the phenomenon mentioned in the first sentence above. With this background then, I introduce a paper that’s almost available online (i.e., we have the DOI, but the online version is yet to appear). Produced by our extremely clever post-doc, Tom Prowse, the paper is entitled: No need for disease: testing extinction hypotheses for the thylacine using multispecies metamodels, and will soon appear in Journal of Animal Ecology.

Of course, I am biased being a co-author, but I think this paper really demonstrates the amazing power of retrospective multi-species systems modelling to provide insight into phenomena that are impossible to test empirically – i.e., questions of prehistoric (and in some cases, even data-poor historic) ecological change. The megafauna die-off controversy is one we’ve covered before here on ConservationBytes.com, and this is a related issue with respect to a charismatic extinction in Australia’s recent history – the loss of the Tasmanian thylacine (‘tiger’, ‘wolf’ or whatever inappropriate eutherian epithet one unfortunately chooses to apply). Read the rest of this entry »

Essential predators

21 11 2012

© C. Hilton

Here at ConservationBytes.com, My contributors and I have highlighted the important regulating role of predators in myriad systems. We have written extensively on the mesopredator release concept applied to dingos, sharks and coyotes, but we haven’t really expanded on the broader role of predators in more complex systems.

This week comes an elegant experimental study (and how I love good experimental evidence of complex ecological processes and how they affect population persistence and ecosystem stability, resilience and productivity) demonstrating, once again, just how important predators are for healthy ecosystems. Long story short – if your predators are not doing well, chances are the rest of the ecosystem is performing poorly.

Today’s latest evidence comes from on an inshore marine system in Ireland involving crabs (Carcinus maenas), whelks (Nucella lapillus), gastropd grazers (Patella vulgata, Littorina littorea and Gibbula umbilicalis), mussels (Mytilus edulis) and macroalgae. Published in Journal of Animal Ecology, O’Connor and colleagues’ paper (Distinguishing between direct and indirect effects of predators in complex ecosystems) explains how their controlled experimental removals of different combinations of predators (crabs & whelks) and their herbivore prey (mussels & gastropods) affected primary producer (macroalgae) diversity and cover (see Figure below and caption from O’Connor et al.). Read the rest of this entry »


Get every new post delivered to your Inbox.

Join 6,326 other followers

%d bloggers like this: