Tropical forest resilience depends on past disturbance frequency

16 07 2014

I’ve recently come across an interesting study that perfectly marries palaeo-ecological data with modern conservation philosophy. It’s not often that such a prehistorical perspective dating at least to the Last Glacial Maximum has been used so effectively to inform future conservation outlooks. I’m particularly interested in this sort of approach considering my own palaeo dabblings of late.

Published in Nature Communications this May, Lydia Cole and colleagues’ paper Recovery and resilience of tropical forests after disturbance is a meta-analysis of 71 studies covering nearly 300 disturbance events in tropical forests over the last 20,000 years or so. Using fossil pollen records as an index of vegetation change, they demonstrated the (somewhat intuitive) main result that the time to recovery following a disturbance generally decreases as the past disturbance frequency increased.

This appears to be a vindication of the idea that a system’s adaptive strategies evolve as a product of the local disturbance regime. More importantly, they found that recovery was faster following ‘large infrequent events’, which are natural perturbations such as cyclones and major fires. While most past disturbances were caused by humans clearing forest, the fact that tropical forest systems were most resilient to ‘natural’ events means that if we can’t stop human disturbances, at least we can attempt to emulate natural processes to maximise the rebound potential. Much like many modern forestry operations try to emulate natural disturbances to limit their damage, we should at least manage our impacts by understanding so-called ‘natural’ regimes as much as possible. Read the rest of this entry »

If biodiversity is so important, why is Europe not languishing?

17 03 2014

collapseI don’t often respond to many comments on this blog unless they are really, really good questions (and if I think I have the answers). Even rarer is devoting an entire post to answering a question. The other day, I received a real cracker, and so I think it deserves a highlighted response.

Two days ago, a certain ‘P. Basu’ asked this in response to my last blog post (Lose biodiversity and you’ll get sick):

I am an Indian who lived in Germany for quite a long period. Now, if I am not grossly mistaken, once upon a time Germany and other west european countries had large tracts of “real” forests with bears, wolves, foxes and other animals (both carnivore and herbivore). Bear has completely disappeared from these countries with the advent of industrialization. A few wolves have been kept in more or less artificially created forests. Foxes, deer and hares, fortunately, do still exist. My question is, how come these countries are still so well off – not only from the point of view of economy but also from the angle of public health despite the loss of large tracts of natural forests? Or is it that modern science and a health conscious society can compensate the loss of biodiversity.

“Well”, I thought to myself, “Bloody good question”.

I have come across this genre of question before, but usually under more hostile circumstances when an overtly right-wing respondent (hell, let’s call a spade a spade – a ‘completely selfish arsehole’) has challenged me on the ‘value of nature’ logic (I’m not for a moment suggesting that P. Basu is this sort of person; on the contrary, he politely asked an extremely important question that requires an answer). The comeback generally goes something like this: “If biodiversity is so important, why aren’t super-developed countries wallowing in economic and social ruin because they’ve degraded their own life-support systems? Clearly you must be wrong, Sir.”

There have been discussions in the ecological and sustainability literature that have attempted to answer this, but I’ll give it a shot here for the benefit of readers. Read the rest of this entry »

Incentivise to keep primary forests intact

7 02 2014

The Amazon rainforest. Photo by Rhett A. Butler

I know – ‘incentivise’ is one of those terrible wank words of business speak. But to be heard by the economically driven, one must learn their guttural and insensitive language. I digress …

Today’s post is merely a repost of an interview I did for the new series ‘Next Big Idea in Forest Conservation‘. I’m honoured to have been selected for an interview along with the likes of Bill Laurance and Stuart Pimm.

Consider this my conservation selfie.

An Interview with Corey Bradshaw What is your background?

Corey Bradshaw: I have a rather eclectic background in conservation ecology. I grew up in the wilds of western Canada, the son of a trapper. My childhood experiences initially gave me a primarily consumptive view of the environment from trapping, fishing and hunting, but I learned that without intact environmental functions, these precious resources quickly degrade or disappear. This ironic appreciation of natural processes would later lead me into academia and the pursuit of reducing the rate of the extinction crisis.

I completed my first degrees in ecology in Montréal and the University of Alberta, followed by a PhD in New Zealand at the University of Otago. After deciding to pursue the rest of my career in the Southern Hemisphere, I completed my postdoctoral fellowship at the University of Tasmania. Multiple field seasons in the subantarctic and Antarctica probably assisted in a giving me a burgeoning desire to change gears, so I left for the tropics of northern Australia to begin a position at Charles Darwin University. Being introduced there to conservation greats like Navjot Sodhi (sadly, now deceased), Barry Brook and David Bowman turned my research interests on their ear. I quickly became enamoured with quantitative conservation ecology, applying my skills in mathematics to the plight of the world’s ecosystems. Nowhere did the problems seem more intractable than in the tropics.

I am now based at the University of Adelaide (since 2008) and have a vibrant research lab where we apply our quantitative skills to everything from conservation ecology, climate change, energy provision, human population trends, ecosystem services, sustainable agriculture, human health, palaeoecology, carbon-based conservation initiatives and restoration techniques. How long have you worked in tropical forest conservation and in what geographies? What is the focus of your work? 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 »

Quantity, but not quality – slow recovery of disturbed tropical forests

8 11 2013

tropical regrowthIt is a sobering statistic that most of the world’s tropical forests are not ‘primary’ – that is, those that have not suffered some alteration or disturbance from humans (previously logged, cleared for agriculture, burned, etc.).

Today I highlight a really cool paper that confirms this, plus adds some juicy (and disturbing – pun intended – detail). The paper by Phil Martin and colleagues just published in Proceedings of the Royal Society B came to my attention through various channels – not least of which was their citation of one of our previous papers ;-), as well as a blog post by Phil himself. I was so impressed with it that I made my first Faculty of 1000 Prime recommendation1 of the paper (which should appear shortly).

As we did in 2011 (to which Phil refers as our “soon-to-be-classic work” – thanks!), Martin and colleagues amassed a stunning number of papers investigating the species composition of disturbed and primary forests from around the tropics. Using meta-analysis, they matched disturbed and undisturbed sites, recording the following statistics: Read the rest of this entry »

Improving the Roundtable on Sustainable Palm Oil

23 11 2012

RSPO – don’t be guilty of this

Laurance & Pimm organise another excellent tropical conservation open-letter initiative. This follows our 2010 paper (Improving the performance of the Roundtable on Sustainable Oil Palm for nature conservation) in Conservation Biology.

Scientists Statement on the Roundtable on Sustainable Palm Oil’s Draft Revised Principles and Criteria for Public Consultation – November 2012

As leading scientists with prominent academic and research institutions around the world, we write to encourage the Roundtable on Sustainable Palm Oil (RSPO) to use this review of the RSPO Principles and Criteria as an opportunity to ensure that RSPO-certified sustainable palm oil is grown in a manner that protects tropical forests and the health of our planet. We applaud the RSPO for having strong social and environmental standards, but palm oil cannot be considered sustainable without also having greenhouse gas standards. Nor can it be considered sustainable if it drives species to extinction.

Tropical forests are critical ecosystems that must be conserved. They are home to millions of plant and animal species, are essential for local water-cycling, and store vast amounts of carbon. When they are cleared, biodiversity is lost and the carbon is released into the atmosphere as carbon dioxide, a greenhouse gas that drives climate change.

Moreover, tropical areas with peat soils store even larger amounts of carbon and when water is drained and the soils exposed, carbon is released into the atmosphere for several decades, driving climate changei. In addition, peat exposed to water in drainage canals may decay anaerobically, producing methane – a greenhouse more potent than carbon dioxide.

Palm oil production continues to increase in the tropics, and in some cases that production is directly driving tropical deforestation and the destruction of peatlandsii. Given the large carbon footprint and irreparable biodiversity loss such palm oil production cannot be considered sustainable. Read the rest of this entry »

Protected areas work, but only when you put in the effort

15 11 2012

Apologies for the delay in getting this latest post out. If you read my last one, you’ll know that I’ve been in the United Kingdom for the last week. I’m writing this entry in the train down from York to Heathrow, from which I’ll shortly begin the gruelling 30-hour trip home to Adelaide.

Eight days on the other side of the planet is a bit of a cyclonic trip, but I can honestly say that it was entirely worth it. My first port of call was London where I attended the Zoological Society of London’s Protected Areas Symposium, which is the main topic on which I’ll elaborate shortly.

But I also visited my friend and colleague, Dr. Kate Parr at the University of Liverpool, where I also had the pleasure of talking with Rob Marrs and Mike Begon. Liverpool was also where I first observed the habits of a peculiar, yet extremely common species – the greater flabby, orange-skinned, mini-skirted, black-eyed scouser. Fascinating.

I then had the privilege and serendipitous indulgence of visiting the beautiful and quaint city of York where I gave another talk to the Environment Department at the University of York. My host, Dr. Kate Arnold was simply lovely, and I got to speak with a host of other very clever people including Callum Roberts, Phil Platts, Andy Marshall and Murray Rudd. Between the chats and real ales, mushy peas, pork pies and visits to the Minster, I was in north English heaven.

Enough of the cultural compliments – the title of this post was the take-home message of the ZSL symposium. There I gave a 25-minute talk summarising our recent paper on the performance of tropical protected areas around the globe, and added a few extra analyses in the process. One interesting result that was missing from the original paper was the country-level characteristics that explain variation in protected area ‘health’ (as we defined it in the Nature paper). After looking at a number of potential drives, including per-capita wealth, governance quality, environmental performance, human population density and the proportion of high conservation-value protected areas (IUCN Ia, Ib, II and IV categories), it came out that at least at that coarse country scale that only the proportion of high conservation-value protected areas explained any additional variation in health. In other words, the more category Ia, Ib, II and IV protected areas a country has (relative to the total), the better their protected areas do on average (and remember, we’re talking largely about developing and tropical nations here). Read the rest of this entry »


Get every new post delivered to your Inbox.

Join 6,168 other followers

%d bloggers like this: