ACCORDING to a new NASA study, published this week in Nature Climate Change, higher levels of atmospheric carbon dioxide are likely to increase water-use efficiency in crops, and could potentially mitigate yield losses associated with other effects of climate change.
Though the researchers behind the study acknowledge that ongoing climate change is likely to lead to extremes in temperatures and water scarcity for most areas, the latest research suggests crops might react to higher levels of atmospheric CO2 in two beneficial ways.
Firstly, crop yields could rise as plants increase the rate of photosynthesis, speeding up growth. Secondly, they could use less water through pores in plants’ leaves, which open to collect carbon dioxide and release water vapour – as concentrations of CO2 increase, the pores don’t open as widely.
Commenting on the new research findings, Delphine Deryng from NASA’s Goddard Institute said earlier assessments have focused on the impacts of CO2 on yield. However, the wider scope of the NASA study, which looked at different effects, a range of crops and several global regions, made for some interesting findings.
The researchets used a range of simulations to look at changes in yield and evapotranspiration (plants’ water loss to the atmosphere) for wheat, maize, soybean and rice crops. Deryng and her co-authors assessed the crops based on yield produced per unit of water, which is a common measurement for assessing crop water-use efficiency. She said this approach will be `Critical to anticipating future agricultural water demands.’
The researchers also examined the impacts of different climate change scenarios – some keeping atmospheric CO2 levels at year 2000 levels, others in which concentrations of carbon dioxide double by the year 2080 (a ‘business as usual’ scenario, in which emissions aren’t tackled).
Their results showed yield losses for all four crops grown at 2000 levels of atmospheric CO2, due to higher temperatures and drier conditions. However, all four crops fared better under the ‘business as usual scenario’ due to increased photosynthesis and crop water productivity partially offsetting other impacts of climate change.
For wheat and soybean crops, this increase in photosynthesis and water retention offset yield losses – In Europe and North America, wheat yields could even see increases – though rice crops would be slightly affected and maize crops could be expected to fare poorly. The researchers said maize would perform worse in the higher-0O2 scenario because the plant is already more efficient at using carbon dioxide.
The results also varied by region; maize yields could be expected to fall by 15% in areas that rely on irrigation and 8 percent in rain-fed systems under the `business as usual’ scenario, and by 21% for irrigated maize and 26% for rain-fed maize at 2000 levels.
A similar pattern was observed for rain-fed wheat in hotter, drier regions like Southern Africa and India, which the researchers again put down to more available CO2 for photosynthesis and better water retention to offset increases in temperature.
Cynthia Rosenzweig cautioned: “The uncertainty of carbon dioxide effects are greater in arid regions because experiments have been carried out mostly in temperate legions of the northern hemisphere. We need field observations in these drier regions in order to validate and further improve our models”
The NASA researchers acknowledged that their study didn’t look at some potentially important factors, such as crop nutrition, which could affect the results as imbalances between available nitrogen and carbon could affect crop health. Even so, they said their observations contribute to work looking at growing in a hotter, drier planet.
Conservation groups don’t like ‘unpalatable truth’
THE FARMERS’ Union of Wales has warned that conservation bodies have their heads in the sand over the devastating impact badgers have had on hedgehog numbers, and are doing conservation a great disservice by scapegoating farmers.
The State of British Hedgehogs 2018 report released on February 7 by the British Hedgehog Preservation Society and the People’s Trust for Endangered Species estimates that hedgehog numbers have halved since the beginning of the century, and places the lion’s share of the blame on intensive farming.
However, world leading hedgehog expert Dr Pat Morris, author of The New Hedgehog Book, wrote in his 2006 book “The implications [of high badger population densities] for hedgehog survival are serious…ignoring the issue or pretending that badgers exist only by harmless drinking of rainwater doesn’t help at all.”
A survey of badger numbers between November 2011 and March 2013 found that badger numbers in England and Wales have increased by between 70% and 105% in the past 25 years.
“Dr Morris is named in the State of British Hedgehogs 2018 report as the instigator of the first survey of hedgehogs based on animals killed on roads, but no mention is made of his concerns regarding high badger numbers having such a devastating impact on hedgehogs.
The issue is dismissed and swept under the carpet, despite overwhelming scientific evidence of the impact of badger predation, while farmers are effectively singled out as being to blame,” said FUW President Glyn Roberts.
A 2014 peer reviewed study of hedgehog numbers in ten 100km2 areas where badgers were culled in England found that “…counts of hedgehogs more than doubled over a 5-year period from the start of badger culling, whereas hedgehog counts did not change where there was no badger culling.”
Mr Roberts said: “Of course there are areas where intensive farming has had a detrimental impact on hedgehog numbers, but it is simply wrong to paint the whole of the UK as being like that – the fall in hedgehog numbers has in fact coincided with farmers planting more hedges.”
Mr Roberts added that this view was backed up by the RSPB, who said that losses of managed hedges appear to have halted in the mid-1990s, while the net length of hedges in the UK was stable or increasing.
The British Hedgehog Preservation Society and the People’s Trust for Endangered Species report said it was planning to engage with the farming community to ‘stem the alarming decline of our country hedgehogs’.
The likelihood is that there is a range of events causing impacts on the hedgehog population. Certain types of pesticides affect the hedgehog’s food chain, while larger and more open fields with less substantial hedgerows might also contribute to hedgehog predation and decline. The increased use of road vehicles is a certain factor, as is urban and suburban spread. Unusually, domestic pets are not a major hazard for hedgehog populations.
In rural Wales, however, the dramatic explosion in badger populations cannot be ignored as a significant factor in driving the decline of hedgehog numbers.
In the early-2000s, an investigation was carried out by the Small Mammal Specialist Group into patterns in hedgehog and badger populations across hundreds of square kilometres of rural southwest England and the midlands. One important finding was that hedgehogs appeared to be absent from large swathes of pastoral grasslands where they are thought to have once been commonplace. The group surveyed hedgehogs in a number of areas which were geographically and ecologically similar, but with different levels of badger culling.
Hedgehog numbers in suburban areas doubled during the five years of badger culling, and remained static in areas without culling. This demonstrated for the first time that badger predation is a strong limiting factor for hedgehog populations in these particular habitats.
Until the mid to late 20th century, heavy persecution of badgers kept them at low numbers. The Badgers Act of 1973 introduced protections, enhanced by the 1992 Protection of Badgers Act. Consequently surveys published in January 2014 revealed that in the 25 years since the first survey in 1985-88, the number of badger social groups in England has doubled to around 71,600.
In pasture-dominated and mixed agricultural landscapes, and in some suburban habitats, badgers thrive with have plentiful denning opportunities and abundant food resources. The largest increases in the density of badger social groups have occurred in the landscapes that dominate southern, western and eastern England. These are also the areas where hedgehog declines are likely to be most severe.
While nobody is suggesting that badgers be culled to improve biodiversity and give hedgehogs a chance of re-establishing themselves, the refusal to acknowledge evidence which they find inconvenient suggests that the weight that can be given to the Hedgehog Survey is questionable.
Glyn Roberts suggested that those ignoring the evidence were simply unprepared to face the truth about natural predation: “By sweeping under the carpet the unpalatable truth that badgers eat hedgehogs, and that the doubling in badger numbers has had a catastrophic impact on hedgehog numbers, and scapegoating farmers by highlighting outdated ideas about hedge removal, conservation bodies are doing a huge disservice to hedgehogs and conservation.
“In fact, they are doing exactly what Dr Pat Morris warned of in his Hedgehog Book – burying their heads in the sand by pretending increased badger numbers are not a major threat to hedgehog survival.”
Charities benefit from breakfast fundraising
THE EQUIVALENT of a year’s farm income (£13,000) has been raised by the Farmers’ Union of Wales, for its charitable causes – Alzheimer’s Society Cymru and The Farming Community Network.
Speaking about the success of the FUW’s farmhouse breakfast week at the end of January, Union President Glyn Roberts said: “Our staff, members and wonderful volunteers have done an incredible job in raising what is the equivalent of a year’s farm income for many farms in Wales for our chosen charities.
“Farming communities are close-knit communities and this shows what can be achieved when we all come together, with a common goal. Through these events, where we all sat around the kitchen table to talk and share our thoughts about #FarmingMatters, we’ve strengthened ongoing and permanent relationships and established new ones.
“The money we have raised in our rural communities will go towards helping others in our communities – we must never forget that our communities are the engine room of people powered change and also that this strength of community has the power to hold governments to account.”
FMD plans tested
GOVERNMENT departments around the UK are set to carry out simulation exercises to test contingency plans for dealing with any future outbreak of foot-and-mouth disease.
Exercise Blackthorn involved the Animal and Plant Health Agency, the Department for Environment, Food and Rural Affairs (DEFRA), Scottish Government, Welsh Government and the Department of Agriculture, Environment and Rural Affairs in Northern Ireland are set to test their current state of readiness over the next few months.
The EU Directive 2003/85/EC requires Member States to exercise their contingency plans either:
- twice within a five year period; or
- during “the five year period after the outbreak of a major epizootic disease has been effectively controlled and eradicated.”
The first simulation exercise took place on Thursday, February 8, with a further table-top exercise on March 8 followed by a real-time exercise on April 25 and 26 April.
Exercise Blackthorn will end on June 7 with a final table-top exercise. UK chief veterinary officer Nigel Gibbens said regular testing of contingency plans was an important part of making sure the authorities can respond to outbreaks.
“Exercises like this provide an opportunity for teams across government and industry to engage and to learn lessons in a controlled and safe environment,” he said.
“The risk of foot-and-mouth disease arriving in the UK is low but ever present. Government monitors disease outbreaks and incidence around the world assessing risk for the UK and taking action to mitigate risk where possible.”
After being free of FMD since 1968, Great Britain suffered a return of the disease in 2001. The entire outbreak lasted for 221 days and had a devastating impact on the farming industry, rural community and the wider economy across the UK. The UK was officially declared disease free on 22 January 2002.
An exercise evaluation report will be published in the autumn.
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