Unit of competency details

AHCARB501A - Assess trees (Release 1)


Usage recommendation:
Is superseded by AHCARB601 - Examine and assess treesThis unit is not equivalent to AHCARB501A Assess trees 26/Jun/2016
Supersedes RTF5018A - Assess trees09/Jun/2011

ReleaseRelease date
1 1 (this release) 10/Jun/2011


SchemeCodeClassification value
ASCED Module/Unit of Competency Field of Education Identifier 050301 Horticulture  

Classification history

SchemeCodeClassification valueStart dateEnd date
ASCED Module/Unit of Competency Field of Education Identifier 050301 Horticulture  04/Nov/2011 
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Modification History

Not Applicable

Unit Descriptor

Unit descriptor 

This unit covers the process of assessing trees to make recommendations on tree health and condition and defines the standard required to consult with clients and provide a service to assess the health of trees; inspect and assess trees for general condition and diseases; diagnose and determine treatment protocols; record assessment data; assess trees for identification of defects and assess risk of harm; document data and recommendations in an assessment report; and maintain assessment data records.

Application of the Unit

Application of the unit 

This unit applies to the job role of a consulting arborist in the provision of professional services in evaluation of tree pathology and structural tree problems in a wide range of amenity trees and sites in urban and regional settings and to the production of professional documentation to inform and advise a client.

Licensing/Regulatory Information

Not Applicable


Prerequisite units 

Employability Skills Information

Employability skills 

This unit contains employability skills.

Elements and Performance Criteria Pre-Content

Not Applicable

Elements and Performance Criteria



1. Determine tree survey program requirements

1.1. Scope of survey is identified in line with client needs and statutory requirements.

1.2. All current data research relevant to survey requirements is identified, sourced and recorded.

1.3. Processes for data capture are documented.

1.4. Methods of recording assessment data are prepared.

1.5. Equipment for tree assessment is checked and prepared for use.

2. Inspect and assess trees

2.1. Trees are assessed to determine their identification, location, health, growth habit, structure and stability.

2.2. Consideration is given to the tree's age, condition, habitats, wind loading, distribution of foliage, wound size and potential impacts of proposed recommendations.

2.3. Tree locations are identified from a plan according to the size and extent of the project and according to common industry practice.

2.4. Testing equipment is used, where required, to determine age, decay, disease and scope of tree problems.

2.5. Individual trees are assessed and, where required, their value calculated and recorded.

2.6. Observed indications of disease are diagnosed and results recorded.

3. Assess risk of harm

3.1. Trees are assessed to determine their identification of defects.

3.2. Trees are assessed to determine their risk potential and suitable controls are recommended to the client or organisation.

3.3. Hazardous trees are assessed to determine their risk of harm.

3.4. Risk controls are documented and recommended to the client or organisation.

4. Compile a tree assessment report

4.1. Diagnosis of any tree problem relevant to the scope of survey is documented.

4.2. Specific recommendations of remedial action for tree problems are provided and recorded.

4.3. Identification of hazardous trees, recommendations for appropriate remedial actions and appropriate risk controls are recommended and documented, and applied.

4.4. Tree assessment report incorporates all relevant data from the survey in line with client needs.

4.5. Survey and assessment data are stored and maintained as part of professional practice.

4.6. Client is informed and advised of the content and implications of the report and a copy is presented.

Required Skills and Knowledge


This section describes the skills and knowledge required for this unit.

Required skills 

  • identify trees
  • locate trees from a survey plan
  • assess tree health, identify defects, structural issues
  • assess individual trees and groups of trees
  • identify hazards and assess risk potential
  • assess the risk of harm associated with a tree
  • diagnose diseases and health issues
  • use testing equipment
  • analyse assessment and testing results
  • determine management/treatment protocols
  • exhibit professional work practices
  • capture assessment data
  • maintain data records
  • value trees
  • use literacy skills to fulfil job roles as required by the organisation. The level of skill may range from reading and understanding documentation to completion of written reports
  • use oral communication skills/language competence to fulfil the job role as specified by the organisation, including questioning, active listening, asking for clarification, negotiating solutions and responding to a range of views
  • use numeracy skills to estimate, calculate and record complex workplace measures
  • use interpersonal skills to work with others and relate to people from a range of cultural, social and religious backgrounds and with a range of physical and mental abilities.

Required knowledge 

  • identification of a wide range of trees common within the region
  • methods of tree assessment, including the visual tree assessment (VTA) method
  • methods for the detection of decay and structural defects in trees
  • causes of instability, decay, damage and stress in trees
  • interpretation of results from assessment and testing
  • tree physiology and pathology
  • principles of tree selection
  • methods of tree protection
  • methods of determining tree heights
  • application of current tree valuation formulae
  • provision of expert witness statements
  • legal requirements relating to development and existing structures
  • local tree protection and preservation laws
  • low risk arboricultural work practices
  • AS 4373-2007 Pruning of amenity trees
  • relevant codes of practice.

Evidence Guide


The evidence guide provides advice on assessment and must be read in conjunction with the performance criteria, required skills and knowledge, range statement and the Assessment Guidelines for the Training Package.

Overview of assessment 

Critical aspects for assessment and evidence required to demonstrate competency in this unit 

The evidence required to demonstrate competency in this unit must be relevant to workplace operations and satisfy holistically all of the requirements of the performance criteria and required skills and knowledge and include achievement of the following:

  • consult with clients and provide a service to assess the health of trees
  • inspect and assess trees for general condition and diseases
  • diagnose and determine treatment protocols
  • record assessment data
  • assess trees for identification of defects and assess risk of harm
  • document data and recommendations in an assessment report
  • maintain assessment data records.

Context of and specific resources for assessment 

Competency requires the application of work practices under work conditions. Selection and use of resources for some worksites may differ due to the regional or enterprise circumstances.

Range Statement


The range statement relates to the unit of competency as a whole.

Trees may include:

  • all species of trees and woody tree-like vegetation forms.

Assessment may include:

  • forensic investigation and analysis of data and observation resulting in a judgment.

Assessment reports may include:

  • visual tree assessments (VTA)
  • tree audits
  • development applications
  • health assessment
  • management reports
  • biodiversity assessments
  • expert witness statements.

Unit Sector(s)

Unit sector 


Co-requisite units

Co-requisite units 

Competency field

Competency field