CAVAT - 5 Steps

CAVAT - Full Method

CAVAT - Quick Method

Street tree in Buckhurst Hill, Essex

CAVAT - 5 Steps

 

There are 5 steps with associated variables in the CAVAT full method, these are:

 

1)      Step 1: Basic value – unit value x size

 

2)      Step 2: CTI value – location, in terms of population and accessibility.

 

3)      Step 3: Functional value – functional status.

 

4)      Step 4: Adjusted value – amenity and appropriateness.

 

5)      Step 5: Full value – safe life expectancy.

 

The 5 steps are explained fully in the CAVAT Users’ Guide, see LTOA.org.uk.  In summary:

 

1        Step 1: Basic value – gives the replacement value of the tree based on its size alone.

 

2        Step 2: CTI value – adjusts the basic value in terms of the local population density and the tree’s relative accessibility to public view and enjoyment.

 

3        Step 3: Functional value – modifies the CTI value in terms of how functional the tree is, in terms of its health and the percentage of the crown that is present, as against a notional, complete tree of the same DBH.  The functional value is reduced therefore if the tree has a low health status, or has been reduced in crown size or density.

 

4        Step 4: Adjusted value – adjusts the functional value of the tree to reflect its actual performance in its particular situation, as against a notional average tree.  This takes into account the fact that nursery gate prices of trees will reflect factors such as relative difficulty of production that are unrelated to actual performance.

 

5        Step 5: Full value – finally, to express the full CAVAT value, an allowance is made for safe life expectancy.  This follows the approach of Safe Useful Life Expectancy, developed by Jeremy Barrell, but in a way developed specifically by the author to give a robust adjustment within CAVAT.

 

Oak trees line a boundary fence
Beech tree in Epping Forest

CAVAT - Full Method

 

The CAVAT full method is employed to value individual trees, for example when a detailed valuation is required for comparative purposes, or for compensation purposes, or in relation to a subsidence event.

Oak trees at St Mary's Church, Buckhurst Hill, Essex
Oak tree Theydon Bois Green, Essex

CAVAT - Quick Method

The CAVAT Quick Method is designed to give public authorities the information necessary to manage their trees as public assets.  The measurements and judgements necessary to calculate the CAVAT value of the stock as a whole will generally be collected as part of a survey of the general tree stock, but it might be done by extrapolation from a smaller sample.  The CAVAT value may be calculated across a town or borough as a whole, or for a discreet area, such as a neighbourhood, street or park.  The CAVAT quick method will express a value that can be used in relation to asset value management for trees (AVMT).

Chris Neilan measuring the girth of a tree