No seeds, no fruit, no fungi - November!

It's been an odd year in the UK (and elsewhere) - an unusually warm early spring, then a cold, wet early spring and summer and a very variable autumn with frosts and warm periods. Unsurprisingly, this has seriously impacted some of the UK's wildlife negatively. For example, the Big Butterfly Count found declines in many common species, with 11 of the 21 target species decreasing in abundance by more than a third since 2011. There are a number of reasons - low temperatures clearly affect cold-blooded groups such as insects, which in turn reduces the food available for insectivores such as birds and bats. Plant growth is also affected by cold and water-logging, so less sugar is produced, fruit growth is reduced (and what does grow may be affected by moulds and blights and fall early or rot on the plant), leading to less seed production - bad for plant reproduction and seed-feeders such as many winter birds. This is already having visible effects as more unusual species appear in gardens - so, it is even more important to keep bird-feeders full. Poor fruit/seed growth in Scandinavia has already meant that at least a couple of thousand waxwings have flow across the North Sea to NE Britain. There are also less obvious effects. For example, the reduced sugar production means that ectomycorrhizal (externally root-associated) fungi grow poorly despite the damp conditions.

However, not all is doom and gloom. Some species have taken advantage of warm late summer and autumn temperatures to grow and breed - I have certainly seen late bird-nesting activity, and while in south Devon last week (the SW is the warmest part of the country), while some trees were losing their leaves, others were budding as seen here.

Hazel coming into bud in mid-November in south Devon

Late flowering has provided at least some extended nectar availability (apart from ivy which is always a winter source) as seen here where a small Panurgus calcaratus bee is feeding on a yellow composite flower, again in mid-November. Found in a band across SE England it is also known all round the SW coast as you can see on the map here; clearly a species needing warm temperatures as it is absent further north.

Panurgus calcaratus feeding on a yellow composite flower in warm sunny mid-November conditions in south Devon

Warm damp autumn weather has meant that some fungi have done well eventually, such as those living on damp deadwood and leaf-litter, while in our new garden pond, the pond-skaters have bred very successfully and are highly active. Slugs and snails have also had an excellent year, though this is not popular with gardeners and allotment-holders, not to mention those of us with old houses that have little holes where slugs can gain access in the middkle of the night...

Overall, there are sadly probably more wildlife losers than winners, but what does the future hold? Well, nothing is certain, but an important study by Overland et al. (2012) does give some indications. Firstly, as many people have suggested, it isn't just 2012 when the summer has been cold and wet - this is a pattern that seems to have begun in 2007 when there was what appears to be a sustained shift in early summer Arctic winds. This change is linked to increased North American atmospheric blocking which ultimately leads to the southward movement of the jet stream that has been mentioned in TV weather forecasts. The study also looked at why this has happened and has unsurprisingly concluded that climate change is a likely candidate - in particular the melting of Arctic ice (particularly around Greenland, remembering that Greenland is politically European but geographically North American) which highlights the potential connectivity between Arctic climate and mid-latitude weather i.e. the Arctic heats up, the UK gets bad summers.

This is of course an ongoing story - research is undoubtedly ongoing to finesse some of the findings and explanations. As an academic, I find this fascinating but as someone interested in wildlife and environmental issues, I also find it deeply troubling, especially when the UK government seems to be trying to pull back from its low-carbon committments. However, I'll stop there lest the Ecology Spot becomes my political ranting zone!

Reference

Overland, J. E., Francis, J. A., Hanna, E. & Wang, M. (2012). The recent shift in early summer Arctic atmospheric circulation, Geophysical Research Letters 39, L19804 (6pp.)