According to a report in the Times, planting trees in 23,000 hectares a year for the next 40 years would result in just an extra 4% of land for trees, bringing a total of 16% forest in Britain.
In flood plains and upland areas such as Cumbria, where extreme rainfall and flooding is already a reality, there is a need for new forestry to capture rainfall and lessen the flood risk.
Trees in city and town centres would help to mitigate expected higher temperatures, while new woods along rivers will provide shade and help to protect aquatic eco-systems.
Professor Sir David Read, chairman of the study, told The Times that one of the crucial findings of the report was the importance of woods in river catchment areas.
"Trees intercept rainfall and retain water, and one of the problems we are seeing now in the Lake District is (that) there is nothing to stop the water running off the hills," he said.
"We must look again at the contribution of forestry in the uplands and returning them in the direction they once were before we deforested them," he added.
In order to achieve this sylvan future, however, the professor said that Britain must accept the introduction of non-native species to replace native trees.
His scenario envisages many new woodlands for the South of England that would not only capture carbon emissions but that would also be used as an energy crop to reduce the use of fossil fuels.
These woods would comprise willow and poplar, and more mixed deciduous forests of sycamore, ash and birch.

The Scottish landscape would continue to be dominated by conifers, Read suggested, while in Wales there would be a mixture of new broadleaf and conifer plantations. 
According to professor Read, "By increasing our tree cover we can lock up carbon directly. By using more wood for fuel and construction materials we can make savings by using less gas, oil and coal, and by substituting sustainably produced timber for less climate-friendly materials."
"While so many emission-reduction measures have negative connotations, tree planting can be a win, win, win solution: people love trees, we benefit from them in so many different ways, and now we know they could play a significant part in reducing the UK's CO2 emissions," he said.
Nature and extent of UK forest cover

Woodland is the natural climax vegetation over much of the UK. Indeed, the greater part of the UK was historically covered with woodland until large-scale forest clearances instigated by human activities began around 5000 years ago.
 
Perhaps 90% of the UK's forest cover has been lost over the past 5000 years; forests and woodlands today make up about 10% of the land surface (around 2.7 million hectares). The percentages of forest cover in each UK country are: England 7%; Scotland 15%; Wales 12%; Northern Ireland 6%.
 
A significant proportion of UK woodland and forest is owned by the state, in the form of the Forestry Commission in England, Scotland and Wales, and the Forest Service in Northern Ireland. These woodlands are generally managed solely for timber production, or for conservation-based timber production. The remainder are either privately-owned or are owned by other state agencies (e.g. the Ministry of Defence) or Non-Governmental Organisations (NGOs) such as the National Trust or the RSPB
 
Most UK woodlands have been established relatively recently on sites which have not been wooded for a long time. Around 15% of UK woodlands (1.5% of total land area) are ancient in origin (i.e. have been continually wooded since at least 1600 AD).
 
However, the vast majority of this ancient woodland has at some point been subject to some form of traditional management such as coppicing, felling and grazing. In more recent times, many ancient woods were planted with non-native species for forestry purposes, meaning that although woodland cover on such sites has been continuous since 1600, the character of the woodland has been completely altered from its original state. Ancient woodlands can therefore be divided into semi-natural stands (composed mainly of trees and shrubs native to the site) and plantations of predominantly introduced species (usually conifers).
 
The most important woods for biodiversity at a national level are notified as Sites of Special Scientific Interest (SSSIs) in England, Wales and Scotland (under the 1981 Wildlife & Countryside Act), and Areas of Special Scientific Interest (ASSIs) in Northern Ireland (under the 1985 Nature Conservation and Amenity Lands (Northern Ireland) Order). An additional designation indicating areas of European importance is provided by the Special Area for Conservation (SAC) designation under the European Union Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Flora and Fauna. All SACs are, or will be, designated as SSSIs / ASSIs.
 http://www.dnaindia.com/scitech/report_planting-forests-across-britain-will-reduce-co2-emissions_1316227