Major survey of tree population in Lewes

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More than a quarter of Lewes enjoys tree canopy cover, research has revealed.

It has been measured as part of the Friends of Lewes’s Urban Arboretum project.

Using a United States Forest Service (USFS) application called i-tree Canopy it is estimated that Lewes has approximately 26 per cent tree canopy cover.

Trees provide many benefits. These include shade during the hot summer months; the interception of pollutants; carbon sequestration and absorption; rainwater interception, slowing the rate water enters main drainage systems; and a vital habitat for many species.

In addition, and perhaps more importantly to most people, they provide beauty particularly in urban areas.

It is the tree canopy which provides the benefits and the greater the area covered by tree canopy the greater the benefits.

How does the Lewes figure compare with other towns and cities? There have only been a few comparable studies carried out in the UK but the county town stands top of an embryonic league table above Exeter (23 per cent), London (22), Walsall (17.3), Edinburgh (17), Eastbourne (15.9), Wrexham (13), Telford (12.5) and Torbay (11.8).

However, tree populations are dynamic. Trees age and die and while they can be conserved they cannot be preserved. Any tree population needs replenishing if it is to maintain the level of benefits it provides.

This replenishment, in urban areas, is largely through the intervention of people managing existing trees and planting new ones. What to plant where, and the contribution of new planting to the overall tree population, are questions it is difficult to answer without appropriate baseline information.

The Lewes Urban Arboretum project is launching an initiative this summer which will answer some if not all of these questions.

Using another USFS tool called i-tree Eco, a full survey of Lewes’s trees will take place with data collection and management being carried out by students from Plumpton College.

The project involves the surveying of 220 randomly selected 11-metre radius plots across the Lewes town area, whether they fall on public or private land. These plots will be visited by the data collection teams and the leaf biomass and other factors assessed using recognised protocols. The data collected is then coupled with pollution and weather data for final analysis. The project will be approaching home and land owners in advance to seek their permission for the surveys.

The outcome is an assessment of the Lewes tree population giving information on species mix, age range and the amount of space available for new planting, as well as the environmental measures mentioned earlier.