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 »

Transition from the Anthropocene to the Minicene

24 09 2016
Going, going ...

Going, going … © CJA Bradshaw

I’ve just returned from a life-changing trip to South Africa, not just because it was my first time to the continent, but also because it has redefined my perspective on the megafauna extinctions of the late Quaternary. I was there primarily to attend the University of Pretoria’s Mammal Research Institute 50thAnniversary Celebration conference.

As I reported in my last post, the poaching rates in one of the larger, best-funded national parks in southern Africa (the Kruger) are inconceivably high, such that for at least the two species of rhino there (black and white), their future persistence probability is dwindling with each passing week. African elephants are probably not far behind.

As one who has studied the megafauna extinctions in the Holarctic, Australia and South America over the last 50,000 years, the trip to Kruger was like stepping back into the Pleistocene. I’ve always dreamed of walking up to a grazing herd of mammoths, woolly rhinos or Diprotodon, but of course, that’s impossible. What is entirely possible though is driving up to a herd of 6-tonne elephants and watching them behave naturally. In the Kruger anyway, you become almost blasé about seeing yet another group of these impressive beasts as you try to get that rare glimpse of a leopard, wild dogs or sable antelope (missed the two former, but saw the latter). Read the rest of this entry »

Cartoon guide to biodiversity loss XXXVIII

25 08 2016

Another six biodiversity cartoons for your midday chuckle & groan. There’s even one in there that takes the mickey out of some of my own research (see if you can figure out which one). See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

Read the rest of this entry »

Rich and stable communities most vulnerable to change

16 08 2016

networkI’ve just read an interesting new study that was sent to me by the lead author, Giovanni Strona. Published the other day in Nature Communications, Strona & Lafferty’s article entitled Environmental change makes robust ecological networks fragile describes how ecological communities (≈ networks) become more susceptible to rapid environmental changes depending on how long they’ve had to evolve and develop under stable conditions.

Using the Avida Digital Evolution Platform (a free, open-source scientific software platform for doing virtual experiments with self-replicating and evolving computer programs), they programmed evolving host-parasite pairs in a virtual community to examine how co-extinction rate (i.e., extinctions arising in dependent species — in this case, parasites living off of hosts) varied as a function of the complexity of the interactions between species.

Starting from a single ancestor digital organism, the authors let evolve several artificial life communities for hundred thousands generation under different, stable environmental settings. Such communities included both free-living digital organisms and ‘parasite’ programs capable of stealing their hosts’ memory. Throughout generations, both hosts and parasites diversified, and their interactions became more complex. Read the rest of this entry »

Australia pisses away the little water it has

9 05 2016

cow_drinking_australia_dryWater, water nowhere, with little left to drink.

Australians are superlative natural resource wasters, but living in the driest inhabited continent on the planet, you’d think we’d be precious about our water use.

You’d be wrong.

On the contrary, Australia has a huge water footprint (defined as “the total volume of freshwater that is used to produce the goods and services consumed by the people of the nation”). For internal domestic use (i.e., not including agricultural and industrial uses, or water imported directly or within other goods), Australians use about 341000 litres per person per year (data from 1997–2001), which is six times the global average of 57000 litres per person per year (1).

Agricultural production is one of the chief consumers of freshwater around the world. For example, the global average virtual water content of rice (paddy) is 2.29 million litres/tonne produced, and for wheat it is 1.33 litres/tonne. Growing crops for biofuel in particular has a huge water footprint — depending on the crop in question, it takes an average of 1400–20000 litres of water to produce just one litre of biofuel (2). If an agricultural product comes from livestock — say, meat, leather, or wool — the water content is typically much higher because of the feed required to keep the animal alive. For example, it takes about three years to raise beef cattle to slaughtering age, with an average of 200 kg of boneless beef produced per animal. This requires about 1,300 kg of grains, 7200 kg of pasture or hay, and 31000 litres of water for drinking and cleaning. This means that the total amount of water required to produce 1 kg of beef is about 15340 litres (1). For Australia, which has over 20 million or so cattle at any one moment, the water footprint alone should at least be cause for concern the next time you tuck into a steak dinner. Read the rest of this entry »

One-two carbon punch of defaunation

30 04 2016

1-2 punchI’ve just read a well-planned and lateral-thinking paper in Nature Communications that I think readers of CB.com ought to appreciate. The study is a simulation of a complex ecosystem service that would be nigh impossible to examine experimentally. Being a self-diagnosed fanatic of simulation studies for just such purposes, I took particular delight in the results.

In many ways, the results of the paper by Osuri and colleagues are intuitive, but that should never be a reason to avoid empirical demonstration of a suspected phenomenon because intuition rarely equals fact. The idea itself is straightforward, but takes more than a few logical steps to describe: Read the rest of this entry »

Shadow of ignorance veiling society despite more science communication

19 04 2016

imagesI’ve been thinking about this post for a while, but it wasn’t until having some long, deep chats today with staff and students at Simon Fraser University‘s Department of Biological Sciences (with a particular hat-tip to the lovely Nick Dulvy, Isabelle Côté & John Reynolds) that the full idea began to take shape in my brain. It seems my presentation was a two-way street: I think I taught a few people some things, and they taught me something back. Nice.

There’s no question at all that science communication has never before been so widespread and of such high quality. More and more scientists and science students are now blogging, tweeting and generally engaging the world about their science findings. There is also an increasing number of professional science communication associations out there, and a growing population of professional science communicators. It is possibly the best time in history to be involved in the generation and/or communication of scientific results.

Why then is the public appreciation, acceptance and understanding of science declining? It really doesn’t make much sense if you merely consider that there has never been more good science ‘out there’ in the media — both social and traditional. For the source literature itself, there has never before been as many scientific journals, articles and even scientists writing. Read the rest of this entry »