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Meeting report Frost and frogs to heatwaves and hawthorn – weatherand climate impacts on flora and fauna in the UK

Weather – Septem

ber 2012, Vol. 67, No. 9

The study of phenology, of how the sea-sonal variations in climate impact upon plant and animal lifecycles, has been of interest to scientists for many centuries. Indeed, the longest phenological record dates from 801 to 2012 and details the tim-ings of cherry blossom flowering in Japan, whilst datasets in the UK have given us a wealth of information for assessing the immediate impacts of climate change.

The meeting, on 26  May, was hosted by the London Wetlands Centre at Barnes and was opened by Paul Hardaker (then the chief executive of the RMetS); he commented on the importance of weather and climate indi-cators to phenology.

The first presentation was given by the meeting’s organizer, Pete Inness (University of Reading), who explained that an early interest in weather lore led him to a study of phenology. He demonstrated the acces-sibility of phenological records using the Nature’s Calendar open source survey, pro-vided by the Woodland Trust, and noted that animal behaviour tends to be an indica-tion of the current weather whereas plant growth is an indication of the weather of the recent past.

The works of the Marsham family who collected data on 20 species for 27 spring events from 1736 to 1958 were commended at the start of the Margary Lecture given by Albert Phillimore (Edinburgh University). Extensive phenological datasets have been amassed from these and other citizen sci-entists, allowing the environmental cues that plants and animals use that determine phenology to be inferred. An important question is: how does phenology react to temperature and climate change? From two case studies (frog spawning and orange-tipped butterfly interactions with host plants) it was concluded that species made up of locally-adapted populations (frogs in Cornwall) were probably most at risk from an altered climate because they do not have a northward-moving gene pool; there was no evidence for geographic variation. It was envisaged that this work would be extended to examine the consequences of maladap-tion, with further study of the effects of sustained temperature change.

A large standardised dataset of 25 532 rates of phenological change for 726 terres-trial, freshwater and marine taxa from the UK was compiled and used by Stephen Thackeray (Centre for Ecology & Hydrology) in order to

determine if the rates of phenological change were similar across all tropical regions, if rates were increasing and if the decadal average rates varied over the regions. This introduced the idea of tropic mismatching: the timing of resources avail-able could become displaced from the tim-ing of demand for those resources. Alarmingly, this study showed different phenological change for different environments and among organisms at different levels of the food chain: slower from secondary consum-ers than their prey. It was thought this would have a knock-on effect for our native species of birds, such as the pied flycatcher as it would not be able to catch the bugs needed to feed its young if their two life cycles were no longer in synchronisation. It was noted that most spring and summer events now occur earlier in the year and the average rate of change has accelerated with warming.

Eileen Rees (Wildfowl and Wetlands Trust) used case studies of pinkfooted and bar-nacle geese to explain how prevailing weather conditions and climate patterns regulate migratory and breeding cycles in high-latitude avian species. Whilst the birds showed the hereditary traits of early or late arrival, due to site experience or breeding status, the migration pattern was found to be proportional to the amount of daylight only. Satellite tracking revealed that these geese were far more likely to fly with a tailwind, which increased their survival rate, rather than heading into a headwind as they could then become lost at sea. They were more likely to make the arduous crossing over the North Sea when winds were light. The study found that sea-water cover, temperature, visibility, precipitation, fog and the wintering site were not impor-tant to the birds during their migration. The weather was the same at wintering and destination sites for the pinkfooted geese yet different for the barnacle geese. Using a normalised difference vegetation index to determine the onset of spring, it was found that pinkfooted geese would more easily adapt to a warmer spring than would barnacle geese, as it showed a cor-relation in arrival time of the pinkfooted geese with the expectation of the weather being the same at their wintering site. As the barnacle geese did not use the onset of spring to regulate the timing of their migration it was thought that they would not adapt well.

The impact of climate change on the avian community was explored by James Pearce-Higgins (British Trust for Ornithology) who used long-term data to explore how climate fluctuations can affect the survival and breeding of UK bird species. The decline and later increase in the blackbird popula-tion from the mid 1950s, reaching a low in 1995, was taken as an example of a fluctuat-ing population, its survival depending on the mortality rates of both adults and young. Several examples of known climato-logical indicators were cited, including the survival of crane flies, robin, goldfinch, great spotted woodpecker and grey partridge, showing that some well-loved garden birds may benefit from climate change. It was concluded that in the UK there is a negative correlation in avian species between habitat specialisation and the number of birds, so that climate change is bad for specialists and good for more common birds.

Phenological-adaption strategies and novel data collection methods for manage-ment of woodlands were discussed by Matt Wilkinson (Forest Research). In the summer a forest is a net CO2 sink whereas in the win-ter it is a net CO2 source, switching between the two on the day of budburst. A flux tower measured the turbulence within the bound-ary layer and from this was inferred the CO2 flux to which it was proportional. This recorded daily data to find the day of switch-ing from a net source to a net sink in any given year. Digital cameras mounted on the tower and facing downwards measured the relative green component of the image. The same system was developed to process images from 16 000 webcams worldwide thus creating a global network to determine, and track changes in, the onset of summer.

One theme that was evident through the meeting was the increasing awareness of science to biological mismatch and the plight of avian species in the UK due to cli-mate change. Large datasets of phenologi-cal records and advances in satellite imagery and image processing are allowing a more global phenological perspective to come to the foreground.

Correspondence to: Thomas Webb

University of Reading

t.webb@pgr.reading.ac.uk

© Royal Meteorological Society, 2012

DOI: 10.1002/wea.1979