ACIMS Element Occurrences

Overview

An Element Occurrence (EO) is an area of land or water where an Element is or was present on the landscape. Alberta Conservation Information Management System (ACIMS) EOs are a spatial dataset. EOs should have conservation value as evidenced by potential continued presence or regular reoccurrence at this location. The EO concept is part of NatureServe methodology. This methodology is used throughout the NatureServe network, and EOs are created based on the Element Occurrence Data Standard.

Following a consistent methodology is beneficial to conservation planning, since it facilitates status ranking and data comparison between jurisdictions.

ACIMS only collects and processes data for Tracked Elements to create EOs.

Element Occurrences

Occurrence versus observation

Observations are the raw data collected during field surveys or associated with biological specimens. These observations can be used to create EOs, if they meet the criteria in the Element Occurrence Data Standard. Observations may represent an ephemeral event (for example, a bird flying overhead) that does not represent potential continued presence or reoccurrence at a location and would not be candidates to be added to an EO.

EO specifications and Separation Distance

In the ideal case EOs should represent independent units, or populations, of an Element. Thus, EOs can be created from multiple observations, including repeated observations at the same site, or observations recorded within the same spatial area.

Multiple factors are relevant to determining if observations should be combined into a single EO or split into multiple EOs, these include:

• dispersal characteristics of the Element
• distance between observations (Separation Distance)
• habitat or landscape characteristics between observations

EO specifications have been developed for ecological communities, species groups and some individual species. These specifications are used to guide EO creation when possible.

• Animal EO Specifications
• Plant EO Specifications
• Ecological EO Specifications

Locational uncertainty

ACIMS receives various types of observation data to be processed into EOs. In many cases the extent of the observation (for example, boundary of a rare plant patch) has not been rigorously mapped. Additionally, there is often some uncertainty between the recorded location and the true location of an observation, due to equipment used, survey techniques, and other factors.

ACIMS follows NatureServe methodology to incorporate this uncertainty into the EO data provided through ACIMS data products. In most cases, observations are buffered to create final EO shapes that reflect the uncertainty in the data.

For more information, see NatureServe documentation on Locational Uncertainty Type and Locational Uncertainty Distance.

Non-sensitive Element Occurrences

Non-sensitive EOs are occurrences of species or communities that are rare (or of conservation concern) and for which there are no restrictions regarding public access to location data.

Sensitive Element Occurrences

Sensitive EOs are occurrences of species that are rare (or of conservation concern) but in these cases the precise location details cannot be distributed without due cause. In most cases these locations are not freely available because the species are legally listed (for example, under Schedule 1 of the Species at Risk Act) or are of particular concern to the Alberta government

The publicly available spatial data for Sensitive EOs simply shows the Alberta Township Survey townships that overlap those Sensitive features.

It is important to recognize the term ‘Sensitive’ applies only to the spatial data. It is not to be confused with the Alberta General Status Rank designation of Sensitive or with a specific subnational conservation status rank (S-Ranks) that is applied to a species or community. The term sensitive does not imply any assessment of viability of the occurrence in question and is not an evaluation of how susceptible the occurrence may be to disturbance.

For information about requesting Sensitive data, see the ‘Supplemental data requests’ section on Access ACIMS data.