Fertilisers can make plants sicker

25 01 2017

sick-plantLast year we reported experimental evidence that the dilution effect was the phenomenon by which greater biodiversity imparts disease resistance in plant communities. Our latest paper shows the mechanism underlying this.

In my ongoing collaboration with the crack team of plant community ecologists led by Shurong Zhou at Fudan University in Shanghai, we have now shown that nitrogen-based fertilisers — in addition to causing soil damage and environmental problems from run-off — reduce a plant community’s resistance to fungal diseases.

This means that prolonged use of artificial fertilisers can lead to the extinction of the most resistant plant species in a community, meaning that the remaining species are in fact more susceptible to diseases.

Continuing the experimental field trials in alpine meadows of the Tibetan Plateau, we tested the biodiversity resilience of an isolated  plant community to increasing concentrations of nitrogenous fertilisers. In this diverse and pristine ecosystem, we have finally established that extended fertilisation of soils not only alters the structure of natural plant communities, it also exacerbates pathogen emergence and transmission. Read the rest of this entry »

Inexorable rise of human population pressures in Africa

31 08 2016
© Nick Brandt

© Nick Brandt

I’ve been a bit mad preparing for an upcoming conference, so I haven’t had a lot of time lately to blog about interesting developments in the conservation world. However, it struck me today that my preparations provide ideal material for a post about the future of Africa’s biodiversity.

I’ve been lucky enough to be invited to the University of Pretoria Mammal Research Unit‘s 50th Anniversary Celebration conference to be held from 12-16 September this year in Kruger National Park. Not only will this be my first time to Africa (I know — it has taken me far too long), the conference will itself be in one of the world’s best-known protected areas.

While decidedly fortunate to be invited, I am a bit intimidated by the line-up of big brains that will be attending, and of the fact that I know next to bugger all about African mammals (in a conservation science sense, of course). Still, apparently my insight as an outsider and ‘global’ thinker might be useful, so I’ve been hard at it the last few weeks planning my talk and doing some rather interesting analyses. I want to share some of these with you now beforehand, although I won’t likely give away the big prize until after I return to Australia.

I’ve been asked to talk about human population pressures on (southern) African mammal species, which might seem simple enough until you start to delve into the complexities of just how human populations affect wildlife. It’s simply from the perspective that human changes to the environment (e.g., deforestation, agricultural expansion, hunting, climate change, etc.) do cause species to dwindle and become extinct faster than they otherwise would (hence the entire field of conservation science). However, it’s another thing entirely to attempt to predict what might happen decades or centuries down the track. Read the rest of this entry »

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 »

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 CB.com readers. Read the rest of this entry »

Seven signs your country has an environmental problem

29 04 2013

1. It’s almost always hazy – and not just in the cities. The particulate matter pollution makes even sunny days appear like it’s about to rain. To add insult to injury, almost every advertisement with anything to do with ‘outside’ pictures a pristinely blue sky and copious sunshine, without the hint of grey. When stepping off the aeroplane, the distinct taste of tar hits the back of your throat.

2. You can’t drink the water from the tap – not anywhere. In fact, you can’t even brush your teeth with it or risk getting some nasty intestinal parasite.

3. You can’t plant trees fast enough because the frequency of landslips kills hundreds of people yearly.

4. While catching a taxi from the airport, the driver plays a continuous loop of birds singing, because most residents never hear those sounds.

5. You have an economy in over-drive, and yet you still think of yourself as ‘developing’.

6. Emerging infectious disease jumping from livestock to humans is now a near-regular occurrence, with new and weird diseases that threaten to become human pandemics and mutating with alarming speed popping up everywhere. Read the rest of this entry »

Individuals a population to conserve make

28 11 2012
Unique in its genus, the saiga antelope inhabits the steppes and semi-desert environments in two sub-species split between Kazakhstan (Saiga tatarica tatarica, ~ 80% of the individuals) and Mongolia (Saiga tatarica mongolica). Locals hunt them for their meat and the (attributed) medicinal properties of male horns. Like many ungulates, the population is sensitive to winter severity and summer drought (which signal seasonal migrations of herds up to 1000 individuals). But illegal poaching has reduced the species from > 1 million in the 1970s to ~ 50000 currently (see RT video). The species has gone extinct in China and Ukraine, and has been IUCN “Critically Endangered” from 2002. The photo shows a male in The Centre for Wild Animals, Kalmykia, Russia (courtesy of Pavel Sorokin).

In a planet approaching 7 billion people, individual identity for most of us goes largely unnoticed by the rest. However, individuals are important because each can promote changes at different scales of social organisation, from families through to associations, suburbs and countries. This is not only true for the human species, but for any species (1).

It is less than two decades since many ecologists started pondering the ways of applying the understanding of how individuals behave to the conservation of species (2-9), which some now refer to as ‘conservation behaviour’ (10, 11). The nexus seems straightforward. The decisions a bear or a shrimp make daily to feed, mate, move or shelter (i.e., their behaviour) affect their fitness (survival + fertility). Therefore, the sum of those decisions across all individuals in a population or species matters to the core themes handled by conservation biology for ensuring long-term population viability (12), i.e., counteracting anthropogenic impacts, and (with the distinction introduced by Cawley, 13) reversing population decline and avoiding population extinction.

To use behaviour in conservation implies that we can modify the behaviour of individuals to their own benefit (and mostly, to the species’ benefit) or define behavioural metrics that can be used as indicators of population threats. A main research area dealing with behavioural modification is that of anti-predator training of captive individuals prior to re-introduction. Laden with nuances, those training programs have yielded contrasting results across species, and have only tested a few instances of ‘success’ after release into the wild (14). For example, captive black-tailed prairie dogs (Cynomys ludovicianus) exposed to stuffed hawks, caged ferrets and rattlesnakes had higher post-release survival than untrained individuals in the grasslands of the North American Great Plains (15). A clear example of a threat metric is aberrant behaviour triggered by hunting. Eleanor Milner-Gulland et al. (16) have reported a 46 % reduction in fertility rates in the saiga antelope (Saiga tatarica) in Russia from 1993-2002. This species forms harems consisting of one alpha male and 12 to 30 females. Local communities have long hunted this species, but illegal poaching for horned males from the early 1990s (17) ultimately led to harems with a female surplus (with an average sex ratio up to 100 females per male!). In them, only a few dominant females seem to reproduce because they engage in aggressive displays that dissuade other females from accessing the males. Read the rest of this entry »

Empty seas coming to a shore near you

12 07 2012

Last week I had the pleasure of entertaining some old friends and colleagues for a writing workshop in Adelaide (don’t worry – they all came from southern Australia locations, so no massive carbon footprints for overseas travel). I’m happy to report it was a productive (and epicurean) week, but that’s not really the point of today’s post.

One of those participants was long-time colleague, Dr. Rik Buckworth. Rik and I first met in Darwin back in the early 2000s when he was lead fisheries scientist for Northern Territory Fisheries; this collaboration and friendship blossomed into an ARC Linkage Project (with Dr. Mark Meekan of AIMS) on shark fisheries (see some of the scientific outputs from that here, here, here and here). Rik has since moved to CSIRO in Brisbane, but keeps a hand in NT fisheries’ affairs. Incidentally, Rik trained under one of the most well-known fisheries modellers in the world – Carl Walters – when he did his PhD at the University of British Columbia back in the early 1990s.

During our workshop, Rik pointed out a paper he had co-authored back in 2009 in Reviews in Fish Biology and Fisheries that had completely escaped my attention – it’s a frightening and apocalyptic view of the Australasian marine tropics that seems to confirm our predictions about northern Australia’s marine future. Just take a look at the following two figures from their paper (Elasmobranchs in southern Indonesian fisheries: the fisheries, the status of the stocks and management options): Read the rest of this entry »