i-Tree Planting v2.0.2 palm tree CO2 estimate changes

[azelaya]

An i-Tree Planting user in CA questioned very high carbon sequestration estimates for palm trees over 40years. Tall fast growing species such as Bangalow palm (Archontophoenix cunninghamiana) and California palm (Washingtonia filifera) were generating estimates over 30k of CO2 seq. and Queen palm (Arecastrum romanzoffianum) was generating 18k lbs. of CO2 seq over 40years.

i-Tree applications have been limited in estimating ecosystem services for palms due to the lack of palm specific research and equations available and integrated in i-Tree over the years. As a result, online applications like i-Tree Planting used a palm growth equation which was based on averaging of 65 growth equations available in i-Tree Eco, but none of the equations cover palm-like trees or plants in the Liliopsida class. This produced very high estimates particularly for large, fast growing palm trees that had high max height at maturity settings in the underlying model databases.

As an interim fix, a palm equation used in i-Tree Eco previously was applied in the planting calculator which produced CO2 sequestration estimates for palms that were at the low end of known literature ranges. As a result, the palm trees mentioned above are now producing significantly lower estimates in the planting calculator - less than 200lbs of CO2 seq. over 40yrs.

If future versions of i-Tree, Dr. Nowak from the USFS has identified palm specific species equations which will be integrated with updated growth estimates and palm specific ratio adjustments for palm below ground biomass, palm percentage of dry weight and palm leaf carbon content. These adjustments and updates are anticipated in the summer of 2020.