§ Mr. BakerTo ask the Secretary of State for the Environment, Transport and the Regions what research his Department has(a) commissioned and (b) evaluated 7W in relation to the damage caused to native (i) oak and (ii) ash trees arising from (a) air pollution and (b) climate change. [15685]
§ Angela EagleAn annual survey of woodland tree condition in the UK is carried out on behalf of my Department. While there was evidence of decline in the health of woodland oak over the period 1989 to 1993, this trend has been reversed during the past four years. Previous analysis for this survey has indicated that air pollution, such as acid deposition and low level ozone, could account for only a small proportion of the observed changes in tree health. Other stresses, including climatic factors, such as drought stress, are thought to be of much greater significance. Ash, which grows on lime-rich soils, is not susceptible to damage from acid deposition.
Other research and monitoring, commissioned by my Department into the health of non-woodland trees, however, does show that both native ash and oak have experienced damage in recent years, probably due to drought stress. It is too early to say whether recent warm, dry years are a part of a long-term climate change, but they give an indication of the kind of damage which could, in future, become more prevalent.