CORE SERVICES
Our Core Competencies
Tree Survey specialise in the detailed assessments and management of large tree populations.
Our key areas of expertise are as follows:
A preliminary tree assessment (PTA) is a comprehensive survey or assessment of trees within a designated site or parcel of land. These reports are often used in the earliest stages of development planning, prior to the development application (DA) or detailed design. The preliminary tree assessment provides base data and information to guide the layout of the development, including opportunities to retain existing trees.
The first stage of a preliminary tree assessment comprises numbering, tagging, and collecting data for each tree within the site. The second stage of the preliminary tree assessment consists of using the data collected on site in conjunction with a site survey plan to compile a report. General information for each individual tree will include:
- Identification: Allocated number and botanical name.
- Dimensions: Tree height, canopy spread, and trunk diameter at breast height (DBH)
- Condition: Tree health, structure, and age class.
- Significance: Tree significance, useful life expectancy, and priority for retention.
- Protection zones: Tree protection zone (TPZ) and structural root zone (SRZ).
Our preliminary tree assessment report includes a tree location plan prepared using ArcGIS or AutoCAD software. The tree location plan shows the identifying number and location of each tree, the extent of the tree protection zone, and will be colour coded to reflect the retention value of each individual tree (low, medium, and high priority for retention).
A geographic information system (GIS) is a conceptualized framework that provides the ability to capture and analyse spatial and geographic data. GIS applications (or GIS apps) are computer-based tools that allow the user to create interactive queries (user-created searches), store and edit spatial and non-spatial data, analyse spatial information output, and visually share the results of these operations by presenting them as maps.
Tree Survey are experts in GIS, and we use this method for almost all of our projects. Examples of how we apply GIS include but are not limited to:
- Identifying tree locations spatially.
- Generating tree protection zones (TPZ) and structural roots zones (SRZ).
- Overlaying surveys, site plans, proposed roads, utilities, and buildings on tree plans.
- Digitising and analysing development impacts (construction footprints and disturbance footprints).
A tree survey (TS) is a comprehensive assessment of a specified tree population. A tree survey is typically undertaken with the aim of providing base data on the existing tree population to assist in the management and future planning around those trees. The extent of data and key attributes collected for each tree is driven by the overall scope of the project in consultation with the client(s) and relevant stakeholders. Base data or key attributes for each individual tree will typically include:
- Identification: Allocated number and botanical name.
- Dimensions: Tree height, canopy spread, and trunk diameter at breast height (DBH)
- Spatial location: Northing and easting or latitude and longitude of the tree location.
The first stage of a Tree Survey requires the precise and meticulous collection of tree data and spatial locations. When the tree data is collected and analysed, it can be utilised in many different ways:
- Annual mortality adjustments.
- Avian habitat suitability.
- Building energy effects.
- Canopy cover calculations and projections.
- Carbon sequestration and storage.
- Cost-benefit analysis.
- Diversity indices and relative performance.
- Extreme event impacts for weather and pests.
- Golf course management and maintenance.
- Hydrology effects (avoided run-off, interception, transpiration).
- Leaf area and biomass.
- Local government street tree databases.
- Pest risk analysis.
- Planning and design of suburbs and precincts.
- Pollution removal and human health impacts.
- Species condition and distribution.
- Species importance values.
- Tree bio-emissions.
- Tree maintenance and management plans.
- Tree planting inputs.
- Tree pollution removal and human health impacts.
- Ultraviolet radiation (UV) tree effects.
Arboricultural Impact Assessments (AIA)
An arboricultural impact assessment (AIA) is a detailed and comprehensive report that reflects the potential impacts of development on trees within and adjacent to a proposed development site. The assessment provides detailed information on the impact of building, infrastructure, stormwater drainage, and landscape construction on the trees within and adjacent to the proposed footprint. The arboricultural impact assessment will identify any trees that may need to be removed and trees that can be successfully retained. General information for each individual tree will include:
- Identification: Allocated number and botanical name.
- Dimensions: Tree height, canopy spread, and trunk diameter at breast height (DBH)
- Condition: Tree health, structure, and age class.
- Significance: Tree significance, useful life expectancy, and priority for retention.
- Protection zones: Tree protection zone (TPZ) and structural root zone (SRZ).
- Impacts: Any conflict between the development footprint and the tree protection zone.
The arboricultural impact assessment report will include recommendations for site-specific tree-sensitive construction methods and other measures which may mitigate the likely impacts of the works. Our reports include two (2) sets of professional drawings prepared using ArcGIS or AutoCAD software. The first set of drawings displays the identifying number and location of each tree, the extent of the tree protection zone (TPZ), and structural root zone (SRZ) and will be colour coded to reflect any conflict between the development footprint and the protection zone of each individual tree (no encroachment, minor encroachment, major encroachment). The second sets of drawings provide details of tree protection. These plans comprise of colour-coded diagrams showing which trees are proposed to be retained and removed, the location and type of tree protection that is required and any site-specific tree protection mitigations.
TREE PROTECTION PLAN (TPP)
A tree protection plan (TPP) generally follows the arboricultural impact assessment (AIA). The tree protection plan provides details on tree protection mitigations for trees that are proposed to be retained (as determined by the arboricultural impact assessment). The tree protection plan is usually included as a component of the arboricultural impact assessment but may also be supplied as a standalone document.
Our tree protection plans include detailed drawings that are prepared using AutoCAD or ArcGIS drafting software. The general information that is typically included in a tree protection plan includes, but is not limited to:
- The location of each tree, and its identifying number.
- Colour-coded diagrams showing which trees are proposed to be retained and removed.
- The extent of the Tree Protection Zone (TPZ) and Structural Root Zone (SRZ).
- The location and type of tree protection that is required. This may include tree protection fencing, trunk and branch protection, or ground protection.
- Site-specific tree protection mitigations, including locations for non-destructive excavation (NDE) or where the arborist may need to supervise works.
The tree protection plan typically includes details on any inspections, monitoring, or certification that may be required prior to construction, during construction, or after construction has been completed.
Project Arborist Services
The project arborist is responsible for carrying out the inspections, supervision, monitoring, and certification of trees during a development project. Details of the project arborist are often required to be submitted to the consent authority prior to construction.
There are various stages in the development process (from site acquisition to completion) where the AQF level 5 project arborist is required to monitor or provide certification (a written statement of compliance). Three key stages of the development are outlined below:
- Pre-construction: A pre-construction meeting should be attended by the site manager, the project arborist, and contractors to introduce the tree protection plan and its requirements. Fencing and other protection measures are to be installed in compliance with conditions of consent and as detailed in the tree protection plan. Once the tree protection measures have been installed, they must be certified by the AQF level 5 project arborist.
- Construction: The project arborist will generally be required to undertake monthly site inspections to monitor and record the ongoing health and condition of the trees during construction. The project arborist will also be required to supervise and certify any work carried out within the tree protection zone (TPZ). If there is non-compliance with tree protection measures or if trees have been damaged, a time frame for compliance and remedial works should be specified by the AQF level 5 project arborist. The determining authority may need to be notified of non-compliance issues.
- Post-construction: Practical completion assumes that all construction and landscaping works are finished. At practical completion, all remaining tree protection measures (such as tree protection fencing, trunk protection, and ground protection) should be removed. Following the final inspection and the completion of any remedial works, the project arborist should certify (as appropriate) that the completed works have been carried out in compliance with the approved plans and specifications for tree protection. Certification should include a statement on the condition of the retained trees, details of any deviations from the approved tree protection measures, and their impacts on trees.
TREE RISK ASSESSMENTS (TRA)
A tree risk assessment (TRA) is a detailed analysis of the risk posed by a single tree or group of trees within a specific site. Tree risk assessments are often carried out at schools, universities, holiday resorts, parks, and other public spaces where trees have the potential to cause harm to the persons who occupy that space. There are three components to calculating the risk posed by a tree:
- Target: The persons, property, or asset at risk and the likelihood of that target being present/impacted in the event of partial or whole tree failure.
- Size: The size of the tree or branch most likely to impact the target. The size of the failure determines the likely force exerted upon impact.
- Probability: The likelihood of a failure occurring within the assessment period based on the structure and condition of the tree.
The first stage of a tree risk assessment comprises a visual tree assessment of all trees within the site. The visual tree assessment comprises a walkover risk assessment in accordance with the Quantified Tree Risk Assessment (QTRA) method. Where the walkover risk assessment identifies conditions or defects that present an increased risk of tree failure, the identified tree will be assessed using the full QTRA method and a stage one Visual Tree Assessment (VTA) as formulated by Mattheck & Breloer (1994).
Trees identified as posing an increased risk of harm are spatial located, tagged, and allocated an identification number. Following the site inspection, a comprehensive report is prepared to detail the overall structure of each identified tree, the subsequent likelihood of tree failure, and the potential risk of harm posed by that individual tree. General information for each individual tree will include:
- Identification: Allocated number and botanical name.
- Dimensions: Tree height, canopy spread, and trunk diameter at breast height (DBH)
- Condition: Tree health, structure, age class, and any significant/visible defects.
- Risk: Risk of harm, risk rating, and mitigation actions.
Our tree risk assessment includes management/mitigation options to reduce or eliminate the risk posed by each of the identified trees and a tree location plan prepared using AutoCAD or ArcGIS drafting software. The tree location plan displays the location of each identified tree, their allocated number, and risk rating. A photo of each identified tree is provided and included in the report to allow for identification and verification purposes.
TREE DATABASE
A tree database or register is a means to store, retrieve, display, sort, and summarise data (information) that relate to tree assets. This can be an important and useful tool to assist and the planning, management, and maintenance of large tree populations. Our expertise in geographic information systems (GIS) allows us to create, manage and maintain large data sets with extreme precision and attention to detail.
Examples of how a tree database information can be displayed and utilised are listed below:
- Identifying tree locations spatially.
- Generating and displaying tree protection zones (TPZ) and structural roots zones (SRZ).
- Color-coding tree populations based on age class or useful life expectancy (ULE).
- Filtering tree populations based on genus or species.
- Filtering tree populations based on risk rating or priority for the next cycle of tree inspections.
TREE MANAGEMENT PLAN (TMP)
A tree management plan (TMP) is a comprehensive survey or assessment of trees within a designated site or parcel of land. These reports are often used to guide the future use, management, and maintenance of a site. The tree management plan provides base data and information, including the existing health and condition of the trees and any risks that the trees may pose. General information for each individual tree will include:
- Identification:Allocated number and botanical name.
- Dimensions: Tree height, canopy spread, and trunk diameter at breast height (DBH)
- Protection zones: Tree protection zone (TPZ) and structural root zone (SRZ).
- Significance: Tree significance, useful life expectancy, and priority for retention.
- Condition: Tree health, structure, age class, and any significant/visible defects.
- Risk: Risk of harm, risk rating, and mitigation actions.
The tree management plan will include a tree retention value plan. This plan will show the number and location of each tree, the extent of the tree protection zone and will be colour coded to reflect the retention value of each individual tree (low, medium, and high priority for retention). The report will also provide management/mitigation options to reduce or eliminate the risk posed by each of the identified trees.