Where in the world to invest in plant conservation

31 05 2010


It’s been a good few weeks with many of our papers coming out online early – for example, I highlighted one last week on ecosystem function breakdown from global warming.

Although this has been out for a few weeks, our new paper lead by PhD candidate Xingli Giam (formerly of National University of Singapore, recently completed Australian Endeavour Scholar, now at Princeton University and all-round up-and-coming research star), and with contributions from Hugh “Vascular” Tan and Navjot Sodhi of National University of Singapore and me, is entitled Future habitat loss and the conservation of plant biodiversity (just published online in Biological Conservation).

This one is a bit of a complicated one, so let me walk you through it.

Plants not only represent a huge component of global biodiversity (~320 000 species), they represent the ‘habitats’ in which animals live and provide the major source of nutrients to food webs. They also provide most of our food and other materials essential for human existence. Basically we’d be screwed without them.

Because so many of the world’s biomes are severely threatened now because of massive habitat loss, degradation, over-exploitation, invasive species, extinction synergies and climate change, we need to maximise our efficiency in protecting what’s left. While global prioritisation schemes have a fruitful scientific history since Myers & colleagues’ classic paper (see Biodiversity Hotspots), there are a number of problems that plague the concept and its implementation. Read the rest of this entry »

The biodiversity extinction numbers game

4 01 2010

© Ferahgo the Assassin

Not an easy task, measuring extinction. For the most part, we must use techniques to estimate extinction rates because, well, it’s just bloody difficult to observe when (and where) the last few individuals in a population finally kark it. Even Fagan & Holmes’ exhaustive search of extinction time series only came up with 12 populations – not really a lot to go on. It’s also nearly impossible to observe species going extinct if they haven’t even been identified yet (and yes, probably still the majority of the world’s species – mainly small, microscopic or subsurface species – have yet to be identified).

So conservation biologists do other things to get a handle on the rates, relying mainly on the species-area relationship (SAR), projecting from threatened species lists, modelling co-extinctions (if a ‘host’ species goes extinct, then its obligate symbiont must also) or projecting declining species distributions from climate envelope models.

But of course, these are all estimates and difficult to validate. Enter a nice little review article recently published online in Biodiversity and Conservation by Nigel Stork entitled Re-assessing current extinction rates which looks at the state of the art and how the predictions mesh with the empirical data. Suffice it to say, there is a mismatch.

Stork writes that the ‘average’ estimate of losing about 100 species per day has hardly any empirical support (not surprising); only about 1200 extinctions have been recorded in the last 400 years. So why is this the case?

As mentioned above, it’s difficult to observe true extinction because of the sampling issue (the rarer the individuals, the more difficult it is to find them). He does cite some other problems too – the ‘living dead‘ concept where species linger on for decades, perhaps longer, even though their essential habitat has been destroyed, forest regrowth buffering some species that would have otherwise been predicted to go extinct under SAR models, and differing extinction proneness among species (I’ve blogged on this before).

Of course, we could just all be just a pack of doomsday wankers vainly predicting the end of the world ;-)

Well, I think not – if anything, Stork concludes that it’s all probably worse than we currently predict because of extinction synergies (see previous post about this concept) and the mounting impact of rapid global climate change. If anything, the “100 species/day” estimate could look like a utopian ideal in a few hundred years. I do disagree with Stork on one issue though – he claims that deforestation isn’t probably as bad as we make it out. I’d say the opposite (see here, here & here) – we know so little of how tropical forests in particular function that I dare say we’ve only just started measuring the tip of the iceberg.

CJA Bradshaw

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This post was chosen as an Editor's Selection for ResearchBlogging.org

ResearchBlogging.orgStork, N. (2009). Re-assessing current extinction rates Biodiversity and Conservation DOI: 10.1007/s10531-009-9761-9

Save the biggest (and closest) ones

12 11 2008

© somapsychedelica

© somapsychedelica

A paper we recently wrote and published in Biological Conservation entitled Using biogeographical patterns of endemic land snails to improve conservation planning for limestone karsts lead by my colleague Reuben Clements of WWF has recently been highlighted at Mongabay.com. Our main result was that following the basic tenets of the theory of island biogeography, the largest, least-isolated limestone karsts in South East Asia (biologically rich limestone outcrops formed millions of years ago by the deposition of calcareous marine organisms) have the greatest proportion of endemic land snails (a surrogate taxon for uniqueness among other species). I’ll let Rhett at Mongabay.com do the rest (see original post):

Researchers have devised a scientific methodology for prioritizing conservation of limestone karsts, biologically-rich outcroppings found in Southeast Asia and other parts of the world. The findings are significant because karsts – formed millions of years ago by sea life – are increasingly threatened by mining and other development.

Using data from 43 karsts across Peninsular Malaysia and Sabah, authors led by Reuben Clements of WWF-Malaysia reported that larger karsts support greater numbers of endemic snails – a proxy for biological uniqueness among other species – making them a priority for protection.

“Larger areas tend to have greater habitat diversity, which enables them so support a higher number of unique species.” said Clements, species conservation manager for WWF-Malaysia.

With a variety of habitats including sinkholes, caves, cliffs, and underground rivers, and separated from other outcroppings by lowland areas, karsts support high levels of endemism among insects, snails, fish, plants, bats and other small mammals. Animals that inhabit karsts provide humans with important services including pest control, pollination, and a sustainable source of income (swiftlet nests used for bird nest soup, a Chinese delicacy, are found in karst caves). But karsts are increasingly under threat, especially from mining for cement and marble. An earlier study by Clements showed that limestone quarrying is increasing in Southeast Asia by 5.7 percent a year – the highest rate in the world – to fuel the region’s construction boom. The biodiversity of karsts – especially among animals that move to surrounding areas to feed – is also at risk from destruction of adjacent ecosystems, often by loggers or for agriculture.

Clements says the new study, which is published in the November issue of the journal Biological Conservation, will help set conservation priorities for karsts.

“The protection of karsts has been mainly ad hoc and they are usually spared from quarrying by virtue of being situated within state and national parks, or if they possess some form of aesthetic or cultural value,” he said. “Taking Peninsular Malaysia for example, our results suggest that we should set aside larger karsts on both sides of the Titiwangsa mountain range for protection if we want to maximize the conservation of endemic species. Protecting karsts on one side of the mountain chain is not enough.”

“With our findings, we hope that governments would reconsider issuing mining concessions for larger karsts as they tend to be more biologically important,” Clements said.

Tropical Conservation Biology

8 09 2008

An obvious personal plug – but I’m allowed to do that on my own blog ;-)

I’d like to introduce a (relatively) new textbook that my colleagues, Navjot Sodhi and Barry Brook, and I wrote and published last year with Blackwell (now Wiley-Blackwell) Scientific Publishing – Tropical Conservation Biology.

We’re rather proud of this book because it was a timely summary and assessment of the scientific evidence for the degree of devastation facing tropical biodiversity today and in the future. I’ve summarised some of the main issues in a previous post covering a paper we have ‘in press’ that was born of the text book, but obviously the book is a far more detailed account of the problems facing the tropics.

This introductory textbook examines diminishing terrestrial and aquatic habitats in the tropics, covering a broad range of topics including the fate of the coral reefs; the impact of agriculture, urbanisation, and logging on habitat depletion; and the effects of fire on plants and animal survival.

One of the highlights of the book is that each chapter (see below) Includes case studies and interviews with prominent conservation scientists to help situate key concepts in a real world context: Norman Myers (Chapter 1), Gretchen Daily (Chapter 2), William Laurance (Chapter 3), Mark Cochrane (Chapter 4), Daniel Simberloff (Chapter 5), Bruce Campbell (Chapter 6), Daniel Pauly (Chapter 7), Stephen Schneider (Chapter 8), Stuart Pimm (Chapter 9) and Peter Raven (Chapter 10). These biographies are followed by a brief set of questions and answers that focus on some of the most pertinent and pressing issues in tropical conservation biology today. It is our intention that readers of Tropical Conservation Biology will benefit from the knowledge and be inspired by the passion of these renowned conservation experts.


  1. Chapter 1: Diminishing habitats in regions of high biodiversity. We report on the loss of tropical habitats across the tropics (e.g., deforestation rates). We also highlight the drivers of habitat loss such as human population expansion. Finally, we identify the areas in immediate need of conservation action by elucidating the concept of biodiversity hotspots. Read the rest of this entry »

Classics: Island Biogeography

19 08 2008

‘Classics’ is a category of posts highlighting research that has made a real difference to biodiversity conservation. All posts in this category will be permanently displayed on the Classics page of ConservationBytes.com

cimage_4c1402ed91-thumbbMacArthur, R.H. & Wilson, E.O. (1967). The Theory of Island Biogeography. Princeton University Press, Princeton, NJ

Although this classic book was written before the discipline of conservation biology really kicked off, it has to be one of the more influential in terms of reserve design and the estimation of extinction rates. The original theory was proposed as a determinant of total species richness on islands as a function of island size. Put (almost too) simply the bigger the island, the more species it contains. This ultimately lead to the branch of biogeography/conservation biology that applied ‘species-area’ relationships to habitat fragments to extrapolate total species number and more importantly (in the context of the extinction crisis), estimate rates of species loss. The species-area literature is a hot-bed of critique and polemic, yet no one can deny that this seminal book really kicked off the idea that reduced and fragmented areas are bad for biodiversity. We wouldn’t have nature reserves today if it wasn’t for this simple, yet brilliant piece of work.

CJA Bradshaw

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