Estimation of Carbon Equestration Loss by Tree Removal in Trail Segment 9

by Pauline Seeales using https://mytree.itreetools.org/#/location

Detailed explanatory notes on the next page

PART ONE - POSSIBLE REPLACEMENT TREES

Ten year old Street Tree

180 Walnut Ave

PART TWO - EXISTING TREES REMOVED FOR THE ULTIMATE TRAIL

Trail trees Native total number

Native Sig/Her

Native Smaller

Non-Native Total

Non-Nat Smaller

TOTAL CO2

Number of new trees needed for immediate carbon neutrality

Number needed for carbon equality after 5 years - estimate

( estimating average CO2 absorption at 5 years = 15 lbs)

THIS WOULD BE SLIGHTLY OVER a 4:1 RATIO

Note (added 4/18/23)

emissions increase of less the 10,000 tons CO2 is NOT consdiered significant by CEQA

But this tree cutting exceeds that PER YEAR!

Explanation of assumptions used

The website i-Tree calculates individual tree carbon sequestration based on

tree diameter at 4.5 feet height - abbreviated as DBH

Any shading by buildings

Using the DBH numbers in the EIR table 3.3-8 I calcalated a tree in each size category

Per the table Significant are >20"DBH, Heritage > 14" DBH

For the combined category Sig and Heritage I used DBH = 18"

For the smaller trees I used DBH=10"

The species are an estimation based on local knowledge but have a relatively small effect

I simply averaged the CO2 numbers for the species listed

It there are more Eucalyptus and less others this would increase the current sequestration

For the potential replacement trees I visited a local nursery and found trees 8-10ft tall

Tree condition - assumed excellent for replacements and good for existing trees

Assumed no significant shading by buildings

Since the estimation of replacement trees for immediate Carbon Neutrality was very high ~9000

I estimated the replacement carbon sequestration after 5 years

Even that indicated a needed mitigation ratio of 4:1

Obviously this is not a professional evaluation -

but I doubt that a more detailed expert analysis would yield signifigantly different results

If anyone has a detailed breakout of major trees species and the approx. % of each in each size category

I'd love to modify the sheet in use that information

Pauline Seales