Introducing the “Derived Root-system Radius” – An attempt at an evidence-supported-calculation for calculation of buffer zone size in respect of Ancient Semi-natural Woodland, Ancient Trees & Veteran Trees

Abstract

ABSTRACTGovernmental Standing Advice in England recommends a minimum 15 m buffer zone from Ancient Semi-natural Woodland (ASNW), or potentially longer distances for Ancient Trees (AT) and Veteran Trees (VT). This “one-size-fits-all” approach does not account for differences in the biology of individual tree species, or the environmental niches they occupy. The effective capillary range of trees further suggests that in some situations the Standing Advice potentially underestimates the zone of water influence. On the basis of published data linking root area to canopy spread, the estimated root areas of trees in a field sample (n = 112) were defined as the Derived Root-system Radius (DRSR). These results were significantly different from distances recommended within the Standing Advice, which might, therefore, be inadequate to safeguard the full extent of the roots in the greater proportion of the field study samples. In the case of AT and VT, the sensible approach will be to also anticipate any reduction in canopy area by applying both the diameter approach of the Standing Advice, and the DRSR, and adopting the greatest buffer zone.