ELC (FeatureServer)

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Service Description: Polygon layer displaying Toronto and Region Conservation Authority (TRCA) ecological land classification (ELC) data. TRCA's Terrestrial Monitoring and Inventory Group utilizes a variety of data collection methods in order to gain an understanding of the natural system at different scales. The methods have been chosen to complement each other and provide a more complete picture of all the components of the natural system; this provides the information basis for further data analysis and interpretation that will eventually assist land planning decisions and action. ELC is collected on an annual basis in various locations by biologists.

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ELC_trca (0)

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The standard data collection protocol for TRCA since 2001 has been based on parts of the Ecological Land Classification System, or ELC, for Southern Ontario, developed by the Ontario Ministry of Natural Resources (Lee et al., 1998). The ELC method classifies the landscape using an organizational framework of a nested hierarchy of scale. The broadest scale is the ELC Community Class (e.g. Forest), and the most detailed is Vegetation Type (e.g. dry-fresh sugar maple forest). A full ELC survey to the level of vegetation type is a very detailed and time-consuming process. The TRCA protocol for surveying vegetation communities strikes a balance between giving enough detail to provide meaningful descriptions of vegetation communities and the constraints of time and funding. For example, resources are unlikely to be available to pursue detailed soil analysis (as outlined in the ELC field guide) in every patch surveyed in the TRCA jurisdiction, especially in the baseline phase. A code from the ELC system is assigned to each polygon. For reference, a list of communities with their codes, scores, and descriptions is carried into the field by the surveyor. Additional vegetation types described by the TRCA since 2000 that are not found in the ELC field guide are included in this reference list.

ELC Attribute Descriptions
Field Name	Description
OBJECTID	Number uniquely generated for each polygon entry in Arcmap. A new set of numbers is generated each time a new layer is created in Arcmap.
POLY_NO	Number of the ELC community polygon assigned by field staff to manage observations in the field. Used for reference and internal purposes.
DATE	Date the ELC community was collected/observed.
OBSERVER	Name of biologist who recorded the observation.
CPYDENSITY	Canopy Density – A measure of how closed or open the canopy (tallest vegetation) cover is within the community. Estimate based on following cover ranges (<10%, 10-25%, 25-35%, 35-60%, >60%).
BLOCK	Alphabetical value indicating major separated habitat units within a site, usually delineated by major roads bisecting natural cover.
CANOPYSP1	Seven-character flora code of the most prevalent species within the canopy.
CPYDOM1	Ranking of prevalence for the species identified in CANOPSP1 within the canopy.
CPYSP1_STA	ELC species modifier for CANOPYSP1 – provides additional information about relative abundance, identification, or condition of species. This and all ELC species modifiers are described in TRCA (2025): Addendum 2-ELC Species Modifiers.
CANOPYSP2	Seven-character flora code of the second most prevalent species within the canopy.
CPYDOM2	Ranking of prevalence the species identified in CANOPYSP2 within the canopy.
CPYSP2_STA	ELC species modifier for CANOPYSP2.
CANOPYSP3	Seven-character flora code of the third most prevalent species within the canopy.
CPYDOM3	Ranking of prevalence for the species identified in CANOPYSP3 within the canopy.
CPYSP3_STA	ELC species modifier for CANOPYSP3.
CANOPYSP4	Seven-character flora code of the fourth most prevalent species within the canopy.
CPYDOM4	Ranking of prevalence for the species identified in CANOPYSP4 within the canopy.
CPYSP4_STA	ELC species modifier for CANOPYSP4.
MDLDENSITY	Midstory Density – A measure of how closed or open the midstory vegetation cover is within the community. Estimate based on following cover ranges (<10%, 10-25%, 25-35%, 35-60%, >60%).
MIDDLESP1	Seven-character flora code of the most prevalent species within the middle canopy.
MDLDOM1	Ranking of prevalence for the species identified in MIDDLESP1 within the midstory.
MDLSP1_STA	ELC species modifier for MIDDLESP1.
MIDDLESP2	Seven-character flora code of the second most prevalent species within the midstory.
MDLDOM2	Ranking of prevalence for the species identified in MIDDLESP2 within the midstory.
MDLSP2_STA	ELC species modifier for MIDDLESP2.
MIDDLESP3	Seven-character flora code of the third most prevalent species within the midstory.
MDLDOM3	Ranking of prevalence for the species identified in MIDDLESP3 within the midstory.
MDLSP3_STA	ELC species modifier for MIDDLESP3.
MIDDLESP4	Seven-character flora code of the fourth most prevalent species within the midstory.
MDLDOM4	Ranking of prevalence for the species identified in MIDDLESP4 within the midstory.
MDLSP4_STA	ELC species modifier for MIDDLESP4.
LWRDENSITY	Lower (Understory) Density - A measure of how closed or open the understory vegetation cover is within the community. Estimate based on following cover ranges (<10%, 10-25%, 25-35%, 35-60%, >60%).
LOWERSP1	Seven-character flora code of the most prevalent species within the understory.
LWRDOM1	Ranking of prevalence the species identified in LOWERSP1 within the understory.
LWRSP1_STA	ELC species modifier for LOWERSP1.
LOWERSP2	Seven-character flora code of the second most prevalent species within the understory.
LWRDOM2	Ranking of prevalence for the species identified in LOWERSP2 within the understory.
LWRSP2_STA	ELC species modifier for LOWERSP2.
LOWERSP3	Seven-character flora code of the third most prevalent species within the understory.
LWRDOM3	Ranking of prevalence for the species identified in LOWERSP3 within the understory.
LWRSP3_STA	ELC species modifier for LOWERSP3.
LOWERSP4	Seven-character flora code of the fourth most prevalent species within the understory.
LWRDOM4	Ranking of prevalence for the species identified in LOWERSP3 within the understory.
LWRSP4_STA	ELC species modifier for LOWERSP4.
GNDDENSITY	Ground Layer Density – A measure of how closed or open the forest floor vegetation cover is within the community. Estimate based on following cover ranges (<10%, 10-25%, 25-35%, 35-60%, >60%).
GROUNDSP1	Seven-character flora code of the most prevalent species within the ground level.
GNDDOM1	Ranking of prevalence for the species identified in GROUNDSP1 within the ground level.
GNDSP1_STA	ELC species modifier for GROUNDSP1.
GROUNDSP2	Seven-character flora code of the second most prevalent species within the ground level.
GNDDOM2	Ranking of prevalence for the species identified in GROUNDSP2 within the ground level.
GNDSP2_STA	ELC species modifier for GROUNDSP2.
GROUNDSP3	Seven-character flora code of the third most prevalent species within the ground level.
GNDDOM3	Ranking of prevalence for the species identified in GROUNDSP3 within the ground level.
GNDSP3_STA	ELC species modifier for GROUNDSP3.
GROUNDSP4	Seven-character flora code of the fourth most prevalent species within the ground level.
GNDDOM4	Ranking of prevalence for the species identified in GROUNDSP4 within the ground level.
GNDSP4_STA	ELC species modifier for GROUNDSP4.
AGECLASS	Age classification of the ELC community. Derived from successional and chronological age for treed communities only. The five potential age classes are: Pioneer, Young, Mid-Aged, Mature, and Old Growth. Interpretations for these age classes can be found in TRCA (2023): Terrestrial Biological Inventory Data Collection Protocol Update 2023 (Table 2).
ELCCODE1	4–7-character code describing the ELC community. Complete list of codes and descriptions can be found in TRCA (2025): Addendum 3-Vegetation Communities Field Reference List, based on Lee et al. (1998).
INCLUSION1	4–7-character ELC code describing distinct ELC subunit too small to map within the larger ELC community. If present.
INCL1SP1	Seven-character flora code of the most prevalent species within the inclusion (INCLUSION1).
INCL1SP2	Seven-character flora code of the second most prevalent species within the inclusion (INCLUSION1).
INCLUSION2	4–7-character ELC code describing distinct ELC subunit too small to map within the larger ELC community. If present.
INCL2SP1	Seven-character flora code of the most prevalent species within the inclusion (INCLUSION2).
INCL2SP2	Seven-character flora code of the second most prevalent species within the inclusion (INCLUSION2).
COMPLEX1	4–7-character ELC code describing distinct ELC subunit forming interspersed secondary network within the larger ELC community. If present.
COMP1SP1	Seven-character flora code of the most prevalent species within the complex (COMPLEX1).
COMP1SP2	Seven-character flora code of the second most prevalent species within the complex (COMPLEX1).
COMPLEX2	4–7-character ELC code describing distinct ELC subunit existing within the larger ELC community. If present.
COMP2SP1	Seven-character flora code of the most prevalent species within the complex (COMPLEX2).
COMP2SP2	Seven-character flora code of the second most prevalent species within the complex (COMPLEX2).
TRAIL_TRMP	This can result from pedestrians, mountain bikes, and/or off-leash dogs. Urban forest patches with heavy trampling have virtually no ground layer, except scattered exotics such as garlic mustard. Severity for this and all other disturbances below are discussed in TRCA (2023).
BROWSING	Presence of herbivory from deer, geese, or other non-domesticated fauna.
GRAZING	Presence/severity of herbivory from cattle or other livestock.
EXOTICS	Presence/severity of the exotic species present in a community, including all layers.
LOG_CUT	Presence/severity of mechanical clearing of the canopy, including opening of the forest for landscaping purposes.
FLOODING	Presence/severity of periodic or permanent flooding conditions, storm-water flooding including scouring, flattened and muddy vegetation and silt deposits.
BEAVER_ACT	Presence/severity of beaver activity.
TRASH_DMP	Presence/severity of litter, illegal dumping, fire-pits, and crude construction.
FILL_SDMT	Presence/severity of soil removal, dumping of fill, or excavation within the community.
Tree Dieback/Decline	Presence/severity of major, widespread tree decline or death from insect outbreak, disease, poisoning, or flooding.
Storm Damage	Presence/severity of sudden tree blow down or breakage due to storm events (usually multiple trees affected in a similar time frame).
Yard Waste	Presence/severity of organic debris dumped from adjacent properties (potted plants, grass and hedge clippings, including potentially live invasive material).
VERNAL_PL	Vernal pool – presence or absence of ephemeral ponds.
Groundwater Seepage	Presence or absence of groundwater seepage as evidenced by springs, indicator species or iron precipitates.
ORG_HOR	Organic horizon: depth of organic material present along soil profile (cm).
ORG_TEX	Soil texture of organic horizon.
AHOR_DEPTH	Depth of A Horizon (cm).
AHOR_TEX	Soil texture of the A Horizon.
BHOR_DEPTH	Depth of B Horizon (cm).
BHOR_TEX	Soil texture of the B Horizon.
DEPTH_MOTT	Depth to mottles (cm).
DEPTH_GLEY	Depth to gley (cm).
DEPTH_K	Depth to carbonates (cm); an indication of C horizon.
EFFECT_TEX	Effective texture.
MOIST_REG	Moisture regime.
DEPTH_AUG	Total depth augured (cm).
COMMENTS	Additional comments.
ELC_CODE	4–7-character code describing the ELC community. Complete list of codes and descriptions can be found in TRCA (2025): Addendum 3-Vegetation Communities Field Reference List, based on Lee et al. (1998).
ELC_NAME	Common name of the Ecological Land Classification community.
Score_date	Date the L-Rank was calculated.
ELC_Local_Rank	ELC Local Concern Score (L-Rank). Definition and interpretation for this and all score components can be found in TRCA (2024): Scoring and Ranking TRCA's Vegetation Communities, Flora, and Fauna Species.
Local_Occurrence	Local Occurrence score. Average of Local Distribution and Area Score.
Local_Distribution	Local Distribution Score.
Area_Score	Area Score.
Geo_Physical_Requirements	Geophysical Score.
Quality	Score of “100” indicates that ELC code is complete and in current usage. Score of “0” indicates that ELC code is incomplete or invalid.
Shape_Length	Length of the ELC community perimeter (m).
Shape_Area	Area of the ELC community in square metres.

Last updated: September 2025

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