Infestations describe where areas of wilding conifer are located and what their nature is. Over the course of time we can measure how they change as a result of the control activities we conduct.

What are infestations?

Infestations are the stands of wild pines being targeted by the National Wilding Conifer Control Programme. A stand is defined as a homogenous community of trees sufficiently uniform in composition, structure, age and size class distribution, spatial arrangement, site quality, condition, or location to distinguish it from adjacent communities.

Infestations are a crucial feature in the wilding conifer programme as they describe where the conifers are located, what their nature is, and over the course of time we can measure how they change as a result of control activities.

Infestations are characterised by their extent, represented in the WCIS as a polygon shape, and a common set of attributes for that extent, including:

  • Name
  • Target revisit date
  • Species
  • Coning Trees
  • Cultivated
  • Overall percentage cover (Override)
  • Trees under 0.5m
  • Trees 0.5m-2m
  • Trees 2m-5m
  • Trees above 5m
  • Total Trees
  • AOO ha
  • EOO ha
  • Overall percentage cover

Each attribute is covered in more detail in the ‘Infestation attributes’ section below.

Infestations are represented as red polygons in the Wilding Conifer Information System.

How do I define the boundaries of an infestation?

The boundaries of an infestation should be defined by an area of homogenous features. In other words the trees within the boundaries of an infestation should be the same species while also exhibiting a similar density and size class.

This is not a simple task and the boundary where homogenous features end is not typically clear cut and easily represented. As such, a degree of subjective interpretation is required to make the best possible judgement of an infestation’s boundaries.

As a first priority, each infestation needs to be a single species. Where there are multiple species in an area a separate infestation shape must be created (although the area of the shape can be the same, and therefore overlapping) as each species requires a new set of attributes captured.

Figure 1: Spatial view showing two infestations that exist in the same space, with the same shape

As a second priority, each infestation should have a similar density pattern and size class. For example a dense forest of a particular species of old trees can be represented as a single infestation. An area of spread that has recently developed from this dense forest, that is categorised by low density and predominantly saplings, should be represented as a separate infestation.

Figure 2: Spatial view showing multiple infestations with contiguous borders, each with a set of attributes based on a homogenous density and size class of the trees within.

How do I record the extent of an infestation?

The first part of representing infestations in the system is to record their extent by creating a polygon. There are a number of methods available to map the extent of an infestation, including:

Shp and Gpx files (Data Importer Application)

The extent of an infestation can be recorded using a tracking tool which captures a shp or gpx file of the path, or points you have visited while out on site.

The WCIS provides functionality to import a shp or gpx file, using the Data Importer application, and create an infestation polygon from the imported shape, using the Data Maintenance application.

Shp and gpx files can also be imported from your local systems using the Data Importer application. This could be useful where you have existing shapes in your own GPS system that you wish to use as the basis for infestations in the WCIS.

See Data Importer Application for guidance on importing data

Mobile Application

The shape of an infestation can be captured on-site using the Mobile Application. The Mobile Application offers two key methods for defining the shape of an infestation:

Path TrackingPath tracking involves using the Mobile Application’s tracking function to periodically note your geo-location and record a point. When you decide to stop tracking the points captured will form a polygon that defines the extent of the infestation. This could be useful where you are flying a helicopter over an area, or travelling around the extent of an infestation on the ground. It could also be an easy way to form a crude draft shape that can be later refined back in the office.
Manual creationThe manual create function in the Mobile Application allows users to draw the boundaries of the infestation by clicking points on the map to add vertices. When finished the points will connect and create a polygon shape.

See Mobile Application for guidance on creating data

The Mobile Application can be downloaded for free from the App Store for Apple products or the Play Store for Android products.

Pen and Paper (Data Maintenance Application)

It may be most practical to make note of the infestation extent on paper, either by drawing on a map or describing in a notebook where the boundaries geographically lie.

The Data Maintenance Application provides functionality for a user back in the office to interpret your hand drawn notes/maps and create an infestation polygon. This would be done using the create function.

See Data Maintenance Application for guidance on creating data

The Data Maintenance Application also provides a function to upload a scanned map, align it to the topo basemap and convert the hand drawn extents into an infestation feature.

See Data Maintenance Application for guidance on using plans

Aerial photography (Data Maintenance Application)

Aerial photography is a great way to capture a large area of infestation. The photos can be interpreted by a user back in the office and converted into infestation polygons using the create function in the Data Maintenance web application.

See Data Maintenance Application for guidance on creating data

How do I record the attributes of an infestation?

As detailed above we need to describe our infestation by entering a common set of attributes. There are several methods available to record the attributes of an infestation.

Pen and paper (Data Maintenance Application)

Similar to recording the extent of an infestation, it may be most practical to simply record the infestation attributes using pen and paper. The notes you have taken would then be interpreted by a user back in the office and entered into the WCIS using the infestation web form that appears in the Data Maintenance Application after creating an infestation shape via the create function.

See Data Maintenance Application for guidance on creating data

Interpretation of aerial photography (Data Maintenance Application)

Similar to the pen and paper approach a user could interpret the attributes of an infestation from aerial photography while back in the office. The infestation web form that appears in the Data Maintenance Application after creating an infestation shape would be used to input the attributes.

See Data Maintenance Application for guidance on creating data

Mobile Application

The Mobile Application provides functionality to record the infestation attributes via an e-form after you have created a shape via the manual create or path tracking functions. In doing so you can directly enter the infestation attributes, while on-site, without needing to note down on paper.

The table below provides an explanation of each attribute you will need to collect for infestations.

See Mobile Application for guidance on creating data

Infestation attributes

The table below provides a description of each infestation field and how to go about collecting the data point.

FIELD NAME

DESCRIPTION

Name

Enter a self determined name for the infestation. You may wish to apply a naming convention to identify the location and species e.g. Cobb Valley North Douglas Fir

Target revisit date

Enter the date of data collection

Species

Enter the species of conifer. Select an option from the drop down list, you will see each option includes both the common name and scientific name of the species

Coning percentage

Enter an estimate for the percentage of trees that are coning

Cultivated

Enter ‘yes’ if the infestation is a cultivated plantation. Enter ‘no’ if the infestation is a wilding infestation

Overall Percentage Cover (Override)

Where it is impractical to count, or estimate, the number of trees in an infestation  there is an Overall Percentage Cover Override field (see below), which allows users to manually estimate the OPC

The following table provides guidance on estimating Overall Percentage Cover (OPC) using an estimated stems/ha

  • Match the size profile of the infestation to options below and estimate the stems/ha

Trees under 0.5m

Less than 0.5m tall

  • Typically less than 2cm diameter trunk at ground

Enter a count of each size class of tree found in the infestation.

The figures are used to calculate the Total tree count, AOO and Overall Percentage Cover.

If the trees cannot be counted (i.e. high density/too many trees) the Overall Percentage Cover can be manually entered, which will also calculate the AOO

Trees 0.5m-2m

Between 0.5m and 2m tall

  • Typically 2-5cm diameter at ground

Trees 2m-5m

Between 2m and 5m tall

  • Typically less than 20cm diameter at 1.4m high

Trees above 5m

Greater than 5m tall

  • Typically greater than 20cm diameter at 1.4m high

Total tree count

The sum of all tree counts above

Automatically calculated

AOO (Area of Occupancy)

The area within the EOO which is occupied by conifers, measured in ha

Automatically calculated

EOO (Extent of Occurrence)

The total area of the infestation polygon, measured in ha

Automatically calculated

Overall Percentage Cover

This is the percentage of canopy cover within the infestation’s area (i.e. AOO/EOO). The field is automatically calculated using the tree counts and a preset area for each tree size.

For example, an Overall Percentage Cover of 100% represents an infestation that has total canopy cover for the entire extent. An Overall Percentage Cover of 0.001% is likely a very sparse infestation with trees dotted infrequently across the landscape.

Comments

Enter any additional comments you wish to make

 

How and when do I edit the extent of an infestation?

Over time infestations will change. If left alone it is likely the area of infestation will continue to grow and increase in density. Conversely an effective control effort will see the area and density of an infestation reduce.

Survey operations should be periodically conducted (whether a stand alone exercise, or part of on-going control efforts) to reassess the nature of infestations that have been previously recorded. With the end result being a new understanding of the extent and attributes of the infestation at the current point in time. It is crucial that the changes identified are recorded in the system so that change over time can be analysed and used as a powerful message for the success of the programme.

Please use the scenarios below as a guide for when you should update the extent or attributes of an infestation.

The original infestation shape was inaccurate, or crudely drawn

Where an infestation was originally drawn to a low level of data quality (e.g. really high level and large scale), and we now have a better understanding of the extent of the infestation, the shape can be updated. This may involve reshaping the boundaries of the infestation, splitting the infestation into multiple infestations, cutting holes in the infestation, creating new infestations for different species, and so on.

Be sure to also carefully update the attributes of each infestation to accurately reflect their true nature.

See Data Maintenance Application for guidance on modifying data

The infestation was well defined and has now been controlled

Where an infestation has been well defined the shape of the infestation should not change. By preserving the shape of an infestation it becomes much easier to analyse the change over time, as the extent remains the same but the attributes will change.

After a control activity has been carried out the infestation should (hopefully!) reduce in density. This change should be represented by updating the infestation attributes – in particular the tree counts and overall percentage cover.

The infestation has spread beyond the extent of my original infestation

Where an infestation has now spread beyond its original extent the boundaries may be changed if the spread has a homogenous nature to the original extent. This can be done using the reshape function to move the polygon’s vertices to a new location.

However, if the spread is not of a homogenous nature to the original extent (e.g. low density saplings, compared to the original large dense infestation) then a new infestation should be created to represent the spread. As stated above, in the ‘How do I define the boundaries of an infestation’ section, infestations should be defined by areas of homogenous nature such as common density, size class and species.

Be sure to also carefully update the attributes of each infestation to accurately reflect their true nature.

Last Updated: 30 November 2017