Your Wildlife Gardening Gateway

Gardens, Wildlife and Climate Change

...bringing nature closer to home

By Steve Head                               Reviewed by Andrew Salisbury

 

This is a very important topic. While there is a consensus that human induced climate change is happening, its predicted effects on UK weather are full of uncertainties. The UKs climate and weather patterns will change and appear already to be changing.  We are commissioning a full review of how climate change could affect garden wildlife, this temporary page sets out some basic information pointers.

 
Expected climate change
Click the green button to see a more detailed summary of the latest scientific predictions.  All UK regions are expected to experience a rise in temperature, especially in summer, adding potentially more than 5C to daily maximum temperatures. In the winter, daily minimum could rise by about 4C , reducing the likelihood of frosts.   Across the year, predicted changes in rainfall (including snow and hail) are small, but with considerable increases in winter rain, and decreases in summer rain.  This could increase the frequency of seasonal droughts and flooding, and could have impacts on wetland habitats and their ecology. Cloud cover and relative humidity will both be reduced in the summer, increasing direct solar heating and the rate of water loss through evaporation.  Both will add to low summer rainfall to increase stress on plants.
Winners and losers. The southern European hummingbird hawk moth is increasingly seen in southern Britain , but the snow bunting which needs cold conditions may become extinct

Changes already visible

 

Flowering has become up to 13 days earlier, because of warmer springs, but reduction in winter chill has delayed the flowering of some plant species which need a cold snap to trigger flowering. Extreme weather events, like the 1976 drought which killed sycamore and beech, showed how climates change could affect trees.

 

Spawning and hatching are happening earlier in frogs, now even before Christmas in the south-west.  Overall frog and toad populations have declined, consistent with low summer rainfall in the period 2003-2006 (before recent red-leg disease)  - alongside habitat loss.

 

In the UK a wide-range of species have shifted their distributions northwards at the rate of some 10 - 25 km every decade.  The garden tiger moth is now uncommon in the south, but continues to survive in the north, apparently in response to warmer winters. Current warming probably contributed to the spread of bluetongue virus in UK sheep and cattle, as its biting midge vector is spreading north in Europe. Migratory insects are arriving with increasing frequency and new species, such as the tree bumblebee, are now resident in the UK, possibly associated with climate change.

 

Likely future effects on wildlife

 

The trends already visible will continue and become more prominent.  The best current review of likely effects on wildlife is the Terrestrial Biodiversity Climate Change Impacts Report Card 2012 -13, and the bulleted list below is based largely on this.

Climate change impacts on gardens

Gardeners will feel both positive and negative effects of climate change.  Reading University has produced a review Gardening in the Global Greenhouse which comes up with several broad conclusions:

There may be far fewer winters in the future when we will experience prolonged frost and snow, or these beautiful ice flowers formed on a garden pond.
Setting an example for future gardens when summer rainfall is less reliable, the Merton Beds at Oxford University Botanic Garden are an exciting mass of colour and form, using prairie adapted plants from around the world.

Gardens and conservation in a changed world

Gardens may have some important conservation roles under climate change.  They will be better maintained, in terms of protection from gales and drought, than the countryside and nature reserves, and their role in sustaining generalist species may become even greater.  Locally therefore, they will have a mitigating role for wildlife as well as people.

The enormous numbers of gardens, and the short distances between them, mean that they could become extremely significant stepping stones, or even corridors, for mobile species adapting by dispersing towards favourable habitat.  Gardens already contain a very large number of non-native Western Palaearctic plant species, and some of these may become significant as food plants for continental insect species migrating with the changed climatic conditions. 

There remains a concern that some species only currently surviving in gardens through winter protection, could become viable in the countryside, and a small fraction of these could become invasive.  Given however, that the whole pattern of species and communities in Britain will be deeply impacted, it is possible that some of these newly acclimitised species may have positive outcomes for the biodiversity of Britain in the future.

See also: Garden physical environment,      Gardens: Native and non-native species

 

The continental sub-species of the magnificent swallowtail butterfly, which has a far less fussy caterpillar than its extremely rare British variety, recently appears to be breeding in southern England, possibly assisted by climate change.