London: Garden City?

LondonGardenCity
LondonGardenCity

This pioneering study, London: Garden City?, was a partnership project between GiGL, London Wildlife Trust and the Greater London Authority. It was funded by a legacy grant from the Wildlife Trusts.

The report reveals that London’s gardens are changing from green to grey.

Vegetated land in the capital’s gardens has been lost at a rate of two and a half Hyde Parks per year, driven by garden design and maintenance choices. Hard surfacing – including decking and paving – increased by over 25 per cent in the 100 month study period.

Download “London: Garden City?”

Summary report – outlines our key findings and conclusions.

Full report – details the full research project.

Frequently Asked Questions

Why did you carry out this research?

In 2008, GiGL and London Wildlife Trust were active members of London Biodiversity Partnership (since disbanded) and involved in the delivery of biodiversity and habitat action plans, including for private gardens. We had a good shared knowledge of the key habitats in London but there was a crucial gap in data for gardens – their coverage and general structure.

The emergence of high-quality aerial photographs and digital mapping made the task of gathering this data feasible. GiGL proposed a data-led project should address the evidence deficiency and so a partnership was formed.

Resources were secured to carry out the research to:
a) investigate the quantity and coverage of gardens across London,
b) investigate what features gardens broadly consisted of, and,
c) to determine whether we could detect any changes between two periods in time. (Similar work has been carried out in respect of other habitats).

The Greater London Authority supported the project, being particularly interested in how garden quantity and coverage might relate to the influence of planning policy on in-fill development.

Why were these data-sets used, and not those more recent?

The research began at the end of 2008. At that time, the most accurate aerial photographs and mapping available were from 2006-08. The earliest period for which equivalent photographs were available from 1998-9.

The accuracy of the underlying data was key to ensuring a high degree of confidence in the results.

We recognise that further investigation of data from later years would help us to determine where the trends are going.

Did the research look at the same gardens, in the years 1998-9 and 2006-7?

Yes, from a randomly stratified sample of 1,292 plots. The samples covered all boroughs and were chosen as representative areas. Changes were extrapolated from these samples to an estimate for London as a whole.

What confidence do you have in the results?

An indication of the variation in the data is provided by the standard error of the mean of the values that were summed to give the various estimates of total land cover area. These standard errors varied from 2% to 4% of the mean for the main land cover categories. Our confidence in the precision of the various estimates would be of this order, which is why the findings are reported to two significant figures, or the nearest percentage point.

It is more standard to report main findings with their confidence intervals. However, the various biases and the great amount of skew in the distribution of garden sizes made this a technically difficult task, which is why the above indication is provided instead.

100 months isn’t a commonly used timeframe; why was this?

We were confined by the available data-sets, which were on average 8.5 years apart, which is approximately 100 months.

Are some areas of London subject to greater changes than others?

This was not investigated. The gardens looked at were anonymous in their location, although we ensured that there was a consistent spread across London in every borough. However, we recognise that there would be value in investigating this further. Investigation of how changes relate to size of garden and age of housing, if resources permitted, would also be of interest.

Was consideration given – in the analysis of the recorded changes – of the impacts of TV garden makeover programmes?

No direct relationship was investigated of any environmental, cultural or legislative influence that might affect garden design and management. We looked purely at the physical changes within the gardens. However, in trying to understand what might have influenced these changes, the research team were aware of issues such as garden fashions, the influence of TV programmes, and the impacts of controlled parking zones. We have subsequently been made aware that the study period coincided with the broadcast of TV garden makeover programmes. This was entirely coincidental.

Is there a relationship between the changes in gardens and tenure?

This was not investigated. It would have been difficult to research this without further resources, as it ownership is difficult to determine without extensive ground-truthing. The research specifically excluded the gardens and grounds of housing estates (private and social).

For more information about gardening for wildlife, visit www.wildlondon.org.uk