The long-term trend in agricultural subsidies within the EU has been away from production support towards agri-environmental and conservation schemes.
As well as reflecting perceived EU sensibilities, this also is a consequence of adopting a WTO-compliant approach and whether Brexit in fact happens or not, the trend is likely to continue. What is it worth? Putting a value on environmental benefits and conservation items such as trees, or wider social benefits derived from rural land is conceptually difficult.
For a more figures-based approach have a look at the article on Capital Asset Value for Amenity Trees (CAVAT) on the London Tree Officers Association website. This is a methodology developed initially by local authority tree officers, which provides a detailed valuation approach for assessing the value of trees, or the impact of damage to trees. Other methods are available, but this one is widespread. Some of the figures that can result from the application of this method are truly astonishing. This can come as an unpleasant surprise when applied to damaged trees in a rural context, but it is something that in reality will take on great prominence given the trend in subsidy focus.