What is a spatial layer?

A spatial layer is an image which contains regular, gridded data over a specific geographical area, such as the continent of Australia. These spatial layers can be/are often used for contextual visualisation, data extraction and ecological modelling. All spatial layers in the ALA are classified using a three-level hierarchy. The first level has two distinct types of layers: “environmental” and “contextual”. 

Environmental layers are usually comprised of a regular spatial grid where the value for a grid cell is a continuous value - for example, a layer of mean annual temperature in degrees centigrade of terrestrial Australia. Environmental layers in the Spatial Portal are included because they are thought by experts to influence the distribution of organisms. For example, mean annual temperature is known to affect the distribution of most species. 

Figure 1. An example of an environment climate layer showing annual mean precipitation (bioclimatic variable 12), visualized in the spatial portal. Colour gradient red to light blue. Red = high rainfall, blue = low rainfall. White = no data.

Contextual layers are usually comprised of polygons where each polygon represents a region of interest; for example, a layer showing the boundaries of the Australian States and Territories. These contextual layers can provide an interpretation of the distribution of species and help with the management of species or areas. For example, we can determine how species are represented across Australia’s reserve network, or see which species are most common in different Local Government Areas (LGAs pictured in Figure 2). 

Figure 2 An example of a contextual political layer showing Local government areas PSMA 2018. Colours are in alphabetical order, blue = government areas starting with “A”, dark red = government areas starting with “Y”.  

Classification levels two and three provide a concise summary of what type of information the layer contains. For example, in Figure 1 showing mean annual precipitation, this layer is classified as “Climate – precipitation” to denote what kind of climate data the user can expect. In contrast, the local government areas layer is classified as simply “Political” with no further classification. 

Accessing and using spatial layers  

Spatial layers can be accessed and used in several different ways. You can visualise the layers through the spatial portal in a point-and-click fashion. Check out our support articles about using the spatial portal here. If you would like to use spatial layers for modelling purposes we recommend visiting EcoCommons, as the ALA spatial portal will be predominately used for data visualisations.  

If you’d like to download spatial information with occurrence record data, you can do this in two main ways: 

1. Using the ALA occurrence record search: you can download species occurrence records and customise it further to include environmental and contextual layer information at the point of each occurrence record. Go check out our Downloading ALA data help article for more information on how to perform this download.
2. From galah: using the R (and soon Python) programming language, you can download occurrence record data and, similarly to a customised download from the ALA website, you can customise your download and append relevant spatial information. We recommend the galah vignette for more information on getting started with galah.  

 
 
ALA criteria for managing spatial layers

For a layer to be indexed by the ALA it must meet the below conceptual and technical criteria:  

Conceptual requirements

• Layers must have multiple, demonstrable uses, being valuable or critical for a single application is not sufficient for layer inclusion.  
  • Layers can be stored on the geoserver for contractual reasons (e.g. to support specific projects) but this does not mean they will be publicly visible. 
• All layers from a dataset must be included; we will not display a subset of the associated layers. 
• New datasets shouldn’t duplicate existing datasets. I.e. We don’t support large numbers of very similar layers, such as conceptually similar versions of ecosystem classifications, and we do not maintain old versions of updated layers.  
  • Please note this condition can be waived if there are strong reasons why both ‘versions’ are needed. 

• Layers will not be included for the sole reason that they are useful for modelling. 
  • Instead, layers should be maintained that support data filtering and discovery (particularly for biocache), and/or visualisation (spatial portal). 
  • If you require advanced modelling, we recommend EcoCommons.
• Taxon-specific layers are not included.
  • Biogeographic classifications of Australian flora or fauna datasets will not be stored.
  • Broad vegetation classifications (‘ecosystems’) may be included assuming they meet the other criteria.

• The dataset must have a clear licence, attribution/acknowledgement and link to original source.  
  There must be a reliable, active maintainer – preferably an institution – that will continue to post updates, &/or respond to comments or feedback. 
• The dataset must be of a scale relevant to a large area of Australia:
  • The dataset should be high resolution (coarse-scale data is comparatively easy to analyse on users’ own systems making it invaluable for the ALA to store).
  • Large spatial extent (ideally national, but not smaller than state- or territory-wide); anything smaller and a user can upload the data themselves.