How Sapflow Measure proved the effectiveness of trees in a SuDS scheme

A SuDS Scheme was established in North Street, Keighley in Yorkshire for the purpose of providing drainage to a road widening project to create additional 356sq.m on North Street. The SuDS scheme comprised of a number of Acer campestre “Streetwise” (Field Maple) established in GreenBlue Urban tree pits with stormwater runoff fed directly off the road and into the pits interestingly, without any connection to the mains drainage. It was calculated that 7128 litres (7.128cu.m) of water capacity would be needed. Total water storage was calculated at 30.18cu.m priory to secondary infiltration which would be ample for a 1/30 year event over a period of 3 1/2 hours. Actually no issues have been raised as to flooding or puddling of the carriageway along with minimal maintenance! The issue was raised as to whether the stormwater runoff with associated pollutants such as hydrocarbons and heavy metals would affect tree health and limit growth. It was proposed therefore to carry out a Tree Vigour Assessment (Tva) using ICT Sapflow technology by IROS ARB. The Sapflow measurement technology allows us to gain actual real time data on the present moisture levels arising in the tree xylem using heat pulse measure with microprobes. The actual raw data is then processed to provide measurements across the annulus of live sapwood. The measure is then compared with Vapour Pressure Deficit and using the Tva ration algorithm (see www.https://www.iros-uk.com/tree-health-and-vigour-assessment/) we are able to provide a contextual vigour assessment. In this case at Keighley the results were astonishing and demonstrated a Tva ratio of 10.53 which is very high. The result of this was to confirm absolutely that the trees far from being hindered in any way, were growing with remarkable vigour, demonstrating absolutely that the species of trees used were an excellent selection for SuDS systems. This is a very good example of the value of Sapflow Measure Assessment and this service is available for North of England and North Wales and would be of great interest to Landscape Architects and Contractors particularly for assessing vigour of recently established Feature trees in property developments.

For more information on How Sapflow Measure proved the effectiveness of trees in a SuDS scheme talk to Iros Arboriculture Ltd