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by Rebecca Nesbit
Invasive species can have a negative effect on our native species, competing with them for food, eating them, and bringing diseases. Some well known examples in the UK are the grey squirrel, rhododendrons, the harlequin ladybird and Japanese knotweed. Global transport and a changing climate mean the risk of invasive species is increasing, with potential devastating effects. The forestry industry, for example, is particularly vulnerable to the threat of insect pests eating trees.
Knowing this, scientists are keen to predict which areas are under threat of invasion by specific species. These predictions are based on the assumption that a species will colonise areas with the same conditions as its native range. A 2012 paper in Science investigated whether this is true for 50 species of invasive plant – do they occupy the same ‘niche’ in their new range as their native range?
North America and Europe inhabit similar latitudes and hence have similar climatic conditions, so it isn’t surprising that they are vulnerable to the invasion of species from each other. This paper focuses on species invasions on these two continents. Although the invasive species we are familiar with have colonised the UK, Europe is actually a ‘net exporter of invasive species’. Historically there are many examples of Europeans settling on other continents. The spread of people out of Europe has often caused the spread of invasive species.
The paper reports there was little evidence that species invading new areas changed the niche they inhabited. The authors suggested that where, occasionally, plants do invade a new niche the reasons can include hybridisation with a native species or relative freedom from predators that were limiting their distribution in their native ranges.
Having found that species stay in the same conditions in their new range, the authors conclude that it is reasonable to base computer models on the current conditions on which a species are found. This is true both for models predicting the spread of invasive species introduced into new geographical areas and those predicting how species will respond to climate change.
Petitpierre, B., Kueffer, C., Broennimann, O., Randin, C., Daehler, C., & Guisan, A. (2012). Climatic Niche Shifts Are Rare Among Terrestrial Plant Invaders Science, 335 (6074), 1344-1348 DOI: 10.1126/science.1215933
by Rebecca Nesbit
Last night I went to a thought-provoking lecture by Nobel Laureate Professor Elinor Ostrom. She described climate change as a ‘global bad’ and expressed concerns about the chances of reaching a global solution in time. The solutions, she suggested, have to operate on lots of different scales, and she was persuasive in her arguments. In her discussions of how we can encourage people to alter their behaviour to tackle climate change she drew on examples ranging from Police services to fishermen.
The EU fisheries are in a pretty poor state, with widespread fish declines, and trying to make the same rules for the Mediterranean and the Baltic may not by possible. In Maine, however, management by the fishing community in each separate cove has been very successful. The government is supportive of this small-scale management as well as having its own rules.
The large scale is still important; there’s no point in tough regulations in one area if all that happens is that fishermen move elsewhere. It’s not just regulation that we’re talking about: large-scale organisations can share knowledge and resources, for example to help address climate change.
Something else she touched on is finding ways to regulate each other, so that people are deterred from acting selfishly not just by risk of punishment by the authorities but by shaming each other. My last blog post discussed American forests, and Professor Ostrom explained there’s no evidence that large government-protected forests are in better condition. Forests where users monitor each other, however, are doing very well.
She gave an example again from the fishermen in Maine. When they catch a pregnant lobster they throw it back (delicately so the eggs don’t fall off). But first they cut a notch off her tail. Anyone landing a lobster with a notch in their tail can be easily identified as having broken the rules where others have upheld them. This matches the results from social experiments she had performed in the lab: in cooperative games people were much more likely to act for the public good if they could communicate with each other.
She also shared a great tip: when you have a shower you turn the cold tap on because the hot water is too hot. So turn down the water temperature! Having no idea about anything domestic or practical I haven’t a clue how easy this is, but it sounds logical…
The lecture was organised by AAAS, publishers of Science, and took place in the Royal Society which has regular interesting events. Let me know if you fancy going to any and maybe we can catch up.
by Rebecca Nesbit
When a plant photosynthesises it takes carbon dioxide from the air and, combining it with water, produces sugar and oxygen. The sugars produced are used as energy and to make new materials as the plant grows. In this way carbon from the air is converted into carbon stored in plants. For this reason forests act as ‘carbon sinks’.
In this way, USA forests offset about 15% of the country’s carbon emissions from fossil fuel combustion.
If a forest is left to its own devices, carbon dioxide is removed from the air as plants grow and released back into the atmosphere when dead wood decays. But in reality many forests are managed for wood production. The wood is removed from the forest and used for furniture, doors, building etc.
So the wood in our houses stores carbon which was removed from the atmosphere when the plant photosynthesised. Understanding this can help forest management.
In the mid 20th century wood production was high so the amount of carbon stored in harvested wood products was increasing. However, when this wood is disposed of it decays on the landfill site and releases carbon dioxide. In the Northern USA the stock of carbon contained in wood products is actually declining because more wood is being discarded than produced.
A recent paper in Carbon Balance and Management states that American forest managers don’t have the information they need to meet national goals for managing climate change. The authors found that when information about wood production from a particular forest is available this helps guide management practices, and they suggest how such information can guide management decisions across the US.
So the wood in your house is a carbon sink, but of course your house is probably built on land that was once forest – a greater carbon sink than your furniture – and is full of electrical appliances powered by fossil fuels. But we need houses, and management must be based on what we need from forests not just on the carbon balance. Another trade off between needs and climate change.
Stockmann, K., Anderson, N., Skog, K., Healey, S., Loeffler, D., Jones, G., & Morrison, J. (2012). Estimates of carbon stored in harvested wood products from the United States Forest Service Northern Region, 1906-2010. Carbon Balance and Management, 7 (1) DOI: 10.1186/1750-0680-7-1
by Rebecca Nesbit
As many of you know I have just returned from a fabulous trip to São Tomé and Príncipe (highly recommended) and following my adventures I always like to share a bit of what I’ve learnt.
Much of what people eat in São Tomé and Príncipe comes from the forest. When our driver joined us on walks he was always lagging behind and filling his bag with food: coconuts, bits of a climber which adds flavour to soup, land snails… Collecting meat, however, seemed to be a task mainly reserved for children. Boys were often seen with a collection of elastic bands round their wrists, ready for emergency repairs to their catapults. Birds are their main targets, and they’re pretty good at catching them.
This abundance of free food means most people are well fed, but seeing endemic birds floppy in someone’s hands ready for the cooking pot and knowing that the spectacular Dwarf Olive Ibis is in danger of being hunted to extinction can be hard to deal with. To us this is putting valuable wildlife at risk; to them it is a tasty meal.
All we could do when we saw this going on was dream up education schemes or tourism projects that would mean the birds were more valuable alive. I also begrudge hunting less when I think of all the ways in which the food I eat damages wildlife in more subtle ways.
While I was away I read an article in New Scientist about how widespread corruption is and, while most of us see ourselves as honest, we are very easily corrupted. It quoted experiments showing we are happier to do corrupt acts if we are more detached from them. One example was a gambling experiment where participants had the chance to cheat. Cheating was more common when people played with chips which could be exchanged for money than when they played directly with money. The same applies when you instruct someone else to do a corrupt act rather than doing it yourself.
I couldn’t help but see the parallel with wildlife. It was very clear for me to see the link with killing a wild bird to eat it and the species becoming endangered. But with my own food I don’t do the dirty work. When I eat bread I’m detached from the habitat that was destroyed to make way for farmland, or the carbon footprint involved in the growing, transporting and making etc etc. If, when I eat fish, it was me who threw back the bycatch or saw fish numbers dwindling, would I eat it so readily?
Maybe this is one of the reasons why environmentally conscious people such as me continue doing things that threaten biodiversity: we’re sufficiently detached from the problems we cause.
If anyone has any ideas how to tackle this problem I’d love to hear them.
I’ve written another blog post about our trip for the Society of Biology’s blog.
By Rebecca Nesbit
Happy New Year! Last year I blogged about the challenges and promises of second-generation biofuels (those made from agricultural by-products such as straw or from woody plants such as poplar). If these crops are going to be a relatively cheap and sustainable alternative to fossil fuels, we will have to think seriously about genetic modification.
Rice is one of the most important food resources in the world. Its cultivation means about 800 million metric tons of rice straw is also produced annually, which is normally burned or decayed in the field. Getting rid of the straw in this way produces greenhouse gasses such as methane. But what if we could use straw, currently a polluting by-product, as a source of energy?
Woody plants, including the inedible part of food crops, get their strength from lignin and cellulose. Cellulose is basically lots of glucose molecules joined together, so a perfect energy source. But the problem is how to turn it into ethanol to use as biofuel.
The process currently relies on enzymes from bacteria or fungi, but it is extremely expensive. If these enzymes could be produced by GM plants rather than by micro-organisms, the production of ethanol would be cheaper and quicker.
Scientists from Taiwan genetically modified rice plants to contain a gene from a bacteria which produces an enzyme that breaks down cellulose. The enzyme they chose has the advantage that it works best at high temperatures, and doesn’t work well to break down cellulose in conditions found in the field.
They managed to produce rice straw with high levels of the enzyme in it, so with potential to increase the efficiency of biofuel production. The enzyme remains stable in the straw long after the rice has been harvested, and becomes active at higher temperatures.
By choosing an enzyme that only breaks down cellulose at high temperatures, this shouldn’t stop the plant growing normally. However, they found some evidence that the genetically modified plants were shorter, so more experiments are needed to work out whether adding the gene for the enzyme disrupts the growth of the rice.
There are clear environmental benefits to using agricultural waste as a replacement for fossil fuels and to making the process of biofuel production more efficient. But is genetic modification a viable, sensible, or even essential option? As always, I’ll be interested to hear your views.
Chou, H., Dai, Z., Hsieh, C., & Ku, M. (2011). High level expression of Acidothermus cellulolyticus beta-1, 4-endoglucanase in transgenic rice enhances the hydrolysis of its straw by cultured cow gastric fluid Biotechnology for Biofuels, 4 (1) DOI: 10.1186/1754-6834-4-58
The Government is proposing to susidise bioenergy projects as it tries to meet renewable energy targets. Its plans, according to the RSPB, are potentially damaging to habitats and do not deliver necessary reductions in greenhouse gas emissions.
By 12th Jauary, the RSPB are asking people to send a letter or email urging the Government to stop subsidies to large-scale energy-only plants. The details of what the problem is, what to say, and where to post it to can be found here. This campaign is by no means anti-biofuel, it is just anti the proposals as they stand.
I’ve just written – it shouldn’t take long!
by Rebecca Nesbit
Each year, 7.2 million tonnes of fisheries catch gets thrown away as bycatch, including fish, turtles and birds.
Modifying fishing gear is a popular way of reducing this, and to a large extent it can often be effective. However, suitable modifications aren’t always possible, so preventing fishing in certain areas can be the only way to solve the problem. As I’ve blogged before, this brings its own challenges.
A recent paper in PLoS looked at options of biodiversity ‘off-setting’ for seabirds caught as bycatch, much in the same way that carbon offsetting is popular for plane travel. It’s widely acknowledged that this isn’t a long-term solution, but in the short term it may be possible to save more birds by putting money into conservation schemes than it would be by modifying equipment or creating exclusion zones.
Tuna and squid fishing in particular leads to a bycatch of albatross, petrels, and shearwaters which get caught on the hooks of longlines. However, these birds often face a far greater danger in their breeding grounds from invasive mammals, particularly rats and feral cats, which have decimated many seabird colonies. The problem is so severe that most vertebrate extinctions over the past six centuries have been caused by invasive mammals.
To test the idea of biodiversity offsets, this paper uses the example of the tuna fishery which stretches along the east coast of Australia. The main victims here are flesh-footed shearwaters. Possible solutions include only laying lines at night and weighting the lines so they sink out of reach more quickly. These have helped but they can’t eliminate bycatch, and they’re expensive, potentially dangerous to use, and hard to enforce. The authors point out that “like world peace, bycatch elimination cannot be achieved over night”.
The shearwaters are also facing threats in their island breeding colonies, including habitat loss, ingestion of plastic, and predation by rats.
Hopefully, better technical solutions to reducing bycatch will be available in a few years time, so rather than implement what we currently have available, it’s perhaps better to look to other conservation measures to give the shearwater population ‘breathing space’ until a real solution is found. Eradication of rats would benefit the whole island ecosystem, not just the shearwaters. In the example of the flesh-footed shearwaters, eradicating invasive rodents is at least 10 times more cost effective than closing areas of sea to fishing.
The way I see it is that, if I was given a pot of money to save seabirds I would spend it on saving the most birds possible. So if the fishing industry has money to use for conservation maybe it is best put to use on islands not boats. However, biodiversity offsets should be a way of saving more birds, not of saving money.
Another interpretation is, of course, that we shouldn’t eat tuna. It’s delicious, and I do miss it…
Pascoe S, Wilcox C, & Donlan CJ (2011). Biodiversity offsets: a cost-effective interim solution to seabird bycatch in fisheries? PloS one, 6 (10) PMID: 22039422
by Rebecca Nesbit
Foreign adventures often get me thinking, and things I’ve learnt can inspire interesting discussions in real life and on our blog. I have just returned from a trip to Gibraltar and southern Spain – great food, friends and birding. Some of these friends are from the Gibraltar Ornithological and Natural History Society, and this post was inspired by our discussions.
We are all intending to dedicate our careers to protecting biodiversity, and at GONHS they are doing some great work. But when we got onto the question of ‘why’ it emerged that my ultimate motivations were different to some of my friends’. ‘It’s intrinsically valuable’ ‘I protect biodiversity for its own sake’ ‘We messed it up, it’s our duty to protect it’ were arguments put forward, but actually rather different to mine yet are equally valid.
I protect biodiversity for people. We benefit in so many ways: directly from enjoyment (and this isn’t to be underestimated – being around nature has major health benefits), and indirectly from services such as pollination and water purification.
I’m also interested in the wellbeing of other animals who have some kind of ability to feel ‘happiness’. The line is fuzzy and we will never understand exactly what this means, but the point is that my views are about happiness and not necessarily about humans.
I am intrigued to hear the views of more people so I have devised some questions, and hope the discussion will continue in comments at the bottom. If you have received this by email you need to go to the blog to tick your answers to my questions: http://thesciencesays.southernfriedscience.com/biodiversity-questions
It’s also a good chance to share some photos – hover the mouse over these to name the species.
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by Rebecca Nesbit
In many parts of the world, pastoralists lose the grazing they rely upon when they are evicted by forestry agencies, often planting exotic trees. Herders rely on fodder trees in particular because their deep root systems ensure they provide feed even in the dry season. This means that even herders who are allowed to remain on the land have had an important resource replaced with non-native species.
In Northern Pakistan large slopes were planted with exotic trees to overcome deforestation and land degradation caused by over grazing. However, the species weren’t chosen to meet the needs of herders, who lost a resource they relied upon.
As a result, the average herd size owned by each landless pastoralist decreased from 340 to 140 goats and sheep. A quarter of herders gave up their flocks altogether and looked for work. Anyone who owned land on the hillside, however, benefitted because they could sell wood as fuel.
Although the trees are planted to stabilise the overgrazed hillside, they inadvertently cause overgrazing elsewhere. The exotic trees are no good as fodder, and this forces herders to spend more time at both upland and lowland grazing areas, which leads to overgrazing there.
A 2011 paper published by scientists from Switzerland and the University of Central Asia looked at alternatives. They showed that indigenous tree and shrub species have great potential to sustain the pastoral system. The authors identify a range of native species that will provide fodder and shade at different altitudes. These would be viable alternatives to the exotic tree plantations of current afforestation programmes.
As well as damaging the livelihoods of pastoralists and leading to overgrazing elsewhere, planting of exotic trees has led to social tensions as different groups compete for resources. By providing an essential resource, native fodder trees should help stabilise social relationships among landowners, sedentary farming tenants, and landless herders. Promoting these trees can also enhance food security for communities in the mountain valleys of Northern Pakistan.
Shrinking grazing areas are detrimental to the mountain environment and to the livelihoods of local communities. This paper gives hope for improved management techniques which could reduce the effect of shrinking grazing. Happy herders, happy sheep.
Inam-ur-Rahim, Daniel Maselli, Henri Rueff and Urs Wiesmann (2011) Indigenous fodder trees can increase grazing accessibility for landless and mobile pastoralists in northern Pakistan Pastoralism: Research, Policy and Practice, doi:10.1186/2041-7136-1-2
by Rebecca Nesbit
In the race to achieve fuel security and to reduce our reliance on fossil fuels, the US has rapidly increased the volume of bioethanol it produces, from 6.2 billion litres/year in 2000 to 50 billion in 2010. Ethanol has the advantage that it can be mixed with petrol so cars need no conversion. However, most of this growth in ethanol has been from first generation corn ethanol, produced through fermentation. First generation biofuels have the major drawback that they are energy intensive to produce, which can counteract any reduction in green house gas emissions. Also, there is a raging food vs fuel argument surrounding biofuels made from food crops.
To overcome some of these problems, research is taking place into second generation biofuels, made from materials such as forestry wastes, grasses, wastepaper etc. These can be converted into liquid fuel, normally using enzymes. But pre-treatment steps are needed to make the enzymes more effective, and options include grinding, adding acid, steaming, or treatment with fungi. Many of these, however, haven’t made it out of the lab. A paper available this month from Biotechnology for Biofuels predicted trade-offs between different pre-treatment steps for commercial ethanol production from grass straw.
For the same amount of straw put in, using dilute acid, dilute alkali or hot water as pre-treatments produced similar quantities of ethanol. Steam explosion pre-treatment was slightly less effective so yielded less ethanol.
Costs of the plant were highest for alkali pre-treatment, and similar for the other three options, with steam being the lowest. The ethanol production costs varied by a few cents per litre ($0.84 per litre for dilute acid, $0.89 for dilute alkali, $0.81 for hot water and $0.86 for steam explosion). Water use also varied – the thirstiest treatment actually being alkali not water.
They concluded that ethanol price and energy use were highly dependent on the pre-treatment technology, demonstrating the importance of addressing the tradeoffs in costs and environmental impacts of different aspects of the pre-treatment.
New technologies are set to make bioethanol more efficient and less energy intensive to produce, which in turn reduces its environmental impact. Biofuels made with current technologies may give biofuels a bad name, but as technologies making second generation biofuels viable move beyond the lab, their environmental impact will reduce. And there don’t seem to be many viable options available for feeding our cars, so research such as this can shape our future fuel supply.
Deepak Kumar and Ganti S Murthy (2011) Impact of pretreatment and downstream processing technologies on economics and energy use in cellulosic ethanol production
Biotechnology for Biofuels, 4:27 doi:10.1186/1754-6834-4-27
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