The impacts of climate change and air pollution are particularly difficult to identify with a high degree of confidence. One of the main reasons for this is that climate and air pollution are rarely measured at sites where biodiversity is monitored so potential relationships can only be assessed by using interpolated national data. These interpolated values can be reliable in some circumstances (for example nitrogen dioxide deposition or temperature in flat terrain) but can be very unreliable in others (for example ammonia deposition or precipitation in sites with varied topography). The effect of uncritically.
