Introduction

The identification and protection of rare vegetation communities within a planning area is important. Frequently these areas support numerous provincially or regionally rare species. Many plant and animals species depend on rare vegetation communities because they provide critical habitat found nowhere else. On a larger scale, they serve to maintain overall biodiversity; on a smaller scale, they contribute to healthy wildlife populations in the planning area.

While some of these communities have never been common in Ontario, many others have been lost or severely degraded, particularly in southern Ontario. The program and the efforts of researchers and naturalists have helped to identify many of the rare vegetation communities in Ontario. Planning authorities across southern Ontario, using the provincial ELC approach, can further help to identify and then protect these important natural areas.

ELC and the vegetation communities of Ontario

The vegetation communities of Ontario can be surveyed and classified using a process called Ecological Land Classification (ELC). The ELC is the process of arranging or ordering information about land units to better understand their similarities and relationships. The goal of the provincial ELC program is to establish a comprehensive and consistent province-wide approach for ecosystem description, classification, mapping, and data collection. It helps to identify recurring ecological patterns on the landscape to reduce complex natural variation to a reasonable number of meaningful ecosystem units. The ELC framework is being designed to facilitate key conservation, planning, and ecosystem management objectives, at various site to landscape scales of resolution. It will provide community descriptions and sampling methodologies for identifying and mapping valuable natural heritage features and areas. This will help municipalities to meet their obligations under the new system of planning in Ontario as outlined in Policy 2.3 in the Provincial Policy Statement.

The vegetation communities identified by the ELC process are developed through extensive collection and statistical analysis of primarily field data. To date, a complete range of forest communities for northern and central Ontario, and wetland communities for the northwestern part of the province have been identified. In southern Ontario, the ELC is still being developed, but during the interim, existing data have been used to develop a preliminary ecological land classification for southern Ontario. This classification is described in a 1998 publication entitled Ecological Land Classification for Southern Ontario: First Approximation and its Application.

Organization and brief explanation of the ELC framework

There are 6 levels to the ELC arranged in a hierarchy. They are explained in the manual Ecological Land Classification for Southern Ontario: First Approximation and Its Application and vegetation and environmental characteristics are listed for each one. From the largest to the smallest scale they are:

  1. Site Region. The ELC for Southern Ontario applies to Site Regions 6E and 7E.
  2. System: Aquatic, Wetland, Terrestrial. The manual provides a key to determine the type of System.
  3. Community Class. Ultimately the division of Community Classes is based on recurring patterns in plant species associations that have shared physiognomic characteristics, substrate type, geology, and meso- and microclimate, as well as other ecological factors.
  4. Community Series. These units are normally visible and consistently recognizable on aerial photographs or from a combination of maps, aerial photograph interpretation, and other remote sensing techniques. Community Series are the lowest level in the ELC that can be identified without a site visit. They are distinguished based on the type of vegetation cover or the plant form that characterizes the community. Generally, they are identified based on whether the community has open, shrub, or treed vegetation cover, as well as whether the plant form is deciduous, coniferous, or mixed.
  5. Ecosite. This landscape unit represents recurring vegetation and soil types. The manual provides a key to determine the type of Ecosite.
  6. Vegetation Type. This is the finest level of resolution in the ELC hierarchy. Vegetation Types are recurring patterns found in plant species assemblages associated with a particular Ecosite. They are generated by grouping plant communities that are most similar together, based entirely on the plant species composition.

The Ontario Ministry of Natural Resources, Credit Valley Conservation Authority and a private consultant have developed a description framework, field sampling methods, an integrated database, and a manual that might be useful to southern municipalities interested in identifying and describing the vegetation communities within their jurisdiction. The following information is provided below to help municipalities identify and map vegetation communities, especially those that may be rare.

Rare vegetation communities

The ultimate objective is to identify and accurately map the rare vegetation communities found in the planning area. The methods outlined below can be used to identify and map the ELC units at a variety of scales. The list of rare vegetation communities for Site Regions 6E and 7E are listed in Appendix M. A planning authority may wish first to classify all of the land within its jurisdiction and later focus on the rare communities, or it may decide to concentrate only on the rare vegetation communities.

Remote methods such as aerial photograph interpretation, can normally be used to reliably identify vegetation communities to the Community Series level of the ELC hierarchy. However most rare vegetation communities (see Appendix J) have been identified at the Vegetation Type level, the finest scale in the ELC hierarchy. Field investigations are required to reliably identify both the Vegetation Types and Ecosites as information must be collected on soil and site conditions, as well as specific indicator vegetation species.

The identification of the Community Series can be an important first step in the screening process to identify rare vegetation communities because it can indicate where there is a high probability of finding a rare Vegetation Type and where field investigations should be focused. For example, the identification of the Tallgrass Savannah Community Series will indicate the presence of rare vegetation communities because all of the Vegetation Types under this Community Series are rare (see Appendix J). In other situations the identification of the Community Series will not readily indicate the location of the rare vegetation Types. For example, there are 27 Thicket Swamp Types under the Thicket Swamp Community Series (see Appendix J). Of these, 7 Vegetation Types are considered rare (i.e. S1 to S3). Two of them, Paw-paw Mineral Thicket Swamp and Huckleberry Organic Thicket Swamp (only found in one location) are very rare (i.e. S1).

It requires considerable botanical knowledge to identify some of these Vegetation Types, comprised of such species as Buttonbush, Southern Arrow-wood and Spicebush. However, knowing the distribution and preferred habitat of species (see Appendix G) can make it easier. Also lists of species that often are included in wetland evaluations, natural area inventories, site management plans, and consultant reports may assist in locating some of these species and rare vegetation communities.

Many, but not all rare vegetation communities have already been identified and mapped (see Appendix M). The information in Appendix M provides general locations of rare vegetation communities and can be used to identify areas where there may be additional examples of these communities.

Limitations of the ELC

The ELC is becoming the accepted framework for natural community description in Ontario and rare vegetation communities for Site Regions 6E and 7E have been identified and described based on the Ecological Land Classification for Southern Ontario: First Approximation and Its Application. However, there are some challenges when using the ELC and they are outlined below.

  • At the present time, the ELC for Southern Ontario and the 1998 OMNR manual only apply to Site Regions 6E and 7E, an area roughly enclosed by the Ontario-Quebec border, along the north shores of Lake Ontario and Lake Erie, up the eastern shoreline of Lake Huron to the tip of the Bruce Peninsula, around Georgian Bay to Midland, and eastward through Orillia, Marmora, to Arnprior. See Figure 2-1 (site regions). This area does not include Manitoulin Island.
  • The ELC for southern Ontario, based on new data collection and analysis, has only been completed for forest land. However, it will be expanded to include wetlands. In the interim, the first approximation provides an excellent source of information.
  • It can be difficult to determine whether a vegetation community is rare and some communities do not fit easily into the ELC description. Often this is because most natural communities in southern Ontario have been disturbed either directly or indirectly by people. Many communities may have some species that are indicators of a potentially rare community (e.g., some prairie grasses) but lack other key species. Or they may be comprised of a few indicator species and many invasive, exotic species. The site might have once supported a relatively pristine community, but become somewhat degraded or otherwise altered due to changes in land use. Sometimes difficult decisions are required to determine the status of these communities. As a general rule, they should be based on the rarity of the remnant community and the efforts required to restore it. There are a growing number of examples of successful tall-grass prairie restoration projects and remnants of other rare vegetation communities could be restored as well.
  • It can be difficult to accurately map small vegetation communities. A minimum polygon size of 0.5 hectare is a feasible mapping unit for applying the ELC at a scale of 1:10,000. A polygon is a discrete and unique area outlined on a map or aerial photograph that contains more or less homogeneous environmental and vegetation characteristics. A hand-held GPS unit might help to accurately locate some small communities.
  • Effective application of the ELC for Southern Ontario requires skilled field workers with a good knowledge of plants and soil characteristics. Some vegetation communities are quite difficult to describe because they are complex or disturbed to varying degrees.
  • Training of field staff (e.g., instruction on aerial photograph interpretation, soil description, ELC field sampling methodology) might be required if the municipality would prefer to develop in-house knowledge and familiarity with the ELC.
  • Aerial photograph interpretation is a skill that takes considerable practice to develop. Also the planning authority cannot assume that private consultants have this skill.
  • Application of the ELC is potentially expensive because of the volume of information that must be collected during field visits. Field investigations will usually be required to find rare vegetation communities, thus increasing overall costs. Even while working at the landscape scale, a very brief site reconnaissance may be advisable to verify initial community typing obtained from aerial photographs, confirm boundaries, become familiar with the level of variation found within the community,
  • or to check unusual features. This limited ground-truthing allows the photograph interpreter to develop a finer appreciation of the differences between the photograph and the communities on the ground.

How to apply ELC tools and techniques to identify rare vegetation communities for land use planning

The following table provides a brief summary of how the ELC might be applied at both the larger landscape scale and the smaller site scale to achieve several important objectives. The tools and techniques, as well as explanations of them and the ELC terminology (e.g., landform, slope position, vegetation form and cover) and Description Framework are fully explained in the manual Ecological Land Classification for Southern Ontario: First Approximation and Its Application. Also included in the manual are examples of the ELC Field Sampling Methods and Data Cards.

Table L-1: How to apply ELC tools and techniques to identify rare vegetation communities
Objective Landscape scale Site scale
Delineation of the boundaries of potentially rare vegetation communities
  • use aerial photographs, topographical, physiographic, soils &/or other maps & any other pertinent information (e.g., Arnup & Racey 1996 for details on how to interpret aerial photographs) to discern prominent landforms, slope position, drainage pattern, & vegetation form & cover to help to delineate the natural ecological or anthropogenic boundaries of potentially rare vegetation communities
  • same as for landscape scale but also will also include gathering additional information in the field to help further determine boundaries of the rare community
  • look for additional communities within the site based primarily on changes in site conditions & vegetation and delineate their natural or anthropogenic boundaries
Field survey of potentially rare vegetation communities
  • select one or more potentially rare communities identified from the sources above
  • from this list, first visit those with the greatest potential to exhibit rarity for the planning area & use the ELC Field Sampling Methods & Data Cards to collect the necessary data to describe & classify them according to the ELC
  • where necessary, refine earlier interpretations conducted before this field survey
  • conduct more intensive field investigations of priority sites &/or sites for which more information is required
  • collect detailed site & vegetation data for each of these sites using the ELC Field Sampling & Data Cards
Description of potentially rare vegetation communities
  • use the ELC Description Framework to describe the environmental, physical, historical, & vegetation conditions found on the site
  • use other sources of information to help to complete the Description Framework
  • same as for landscape scale but necessarily includes more information collected during site visits
Classification of potentially rare vegetation communities
  • use the information & data documented above to classify the site to the Community Class & Community Series levels in the ELC
  • use the ELC Keys & Community Tables to assign ELC units to the site
  • Note: only Community Class & Community Series level classifications can be achieved without a site visit
  • use information & data documented above to classify the site to Community Class, Community Series, Ecosite, & Vegetation Type levels in the ELC
  • use the ELC Keys & Community Tables to assign ELC units to the site
  • Note: only by using field data can a site be classified according to all the levels in the ELC
Mapping of potentially rare vegetation communities
  • boundaries of rare communities & their corresponding classifications can be mapped by
    1. manually transcribing the boundaries to hard-copy maps or
    2. digitization into Geographical Information Systems (GIS) for digital mapping
  • mapping is to the Community Class or Community Series level in the ELC
  • same as for the landscape scale, however mapping can be done to the Community Class, Community Series, Ecosite, & Vegetation Type level in the ELC

Basic equipment required to identify and map rare vegetation communities

The following list describes basic equipment required to identify and map rare vegetation communities.

  • Maps, especially topographical, physiographical, soils, and Ontario Basic Mapping (OBM). Ontario Basic Mapping (OBM) is available in hard copy and digital format for all of southern Ontario at a scale of 1:10,000. It has become the standard for much of the natural areas mapping being carried out.
  • Aerial photographs. Aerial photography varies considerably in scale, format, resolution, date, and seasonal coverage. However it forms the basis of most of the community mapping that is prepared. Aerial photographs available from the OMNR are mostly at 1:10,000. However if the planning authority wishes to use their own photos, it is suggested that they use those with a scale of 1:8,000 to facilitate interpretation. Also summer photography can be useful for the delineation of forested communities, if the expertise is available to differentiate species in the canopy of trees in full leaf. Spring photography would make areas of conifer and hardwoods, as well as waterbodies, woodland ponds, and flooded lands easier to see.
  • A pocket stereoscope (2X magnification) is used for aerial photograph interpretation.
  • Fine point technical pens (0.35 mm) are used to transcribe community boundaries directly onto the aerial photographs. Their ink can be erased.
  • Although the manual Ecological Land Classification for Southern Ontario: First Approximation and Its Application was designed to produce an ecological land classification of communities for southern Ontario, it can be useful for identifying rare vegetation communities as well. It provides a description of the site, vegetation, and community characteristics that need to be sampled on a site, for the detailed description, identification, and classification of ecological land units in southern Ontario. It also provides details on how to sample characteristics, and a set of standardized data cards that can be used to record the collected information.
  • A soil auger or Oakfield Tube to sample soils.
  • Field guides for vascular plants to aid in plant identification.
  • A plant press for collecting plants that require future identification.
  • A Wedge Prism with a 2X prism factor to determine forest stand composition and basal area.
  • Copies of information/data collection forms: ELC Community Description & Classification; ELC Stand & Soil Characteristics; ELC Plant Species List; ELC Management/Disturbance; and ELC Wildlife forms (sample copies are included in Ecological Land Classification for Southern Ontario: First Approximation and Its Application).
  • There are several ways to transfer community boundaries interpreted from aerial photographs, to the OBMs. Boundaries can be drawn on mylar overlays placed on top of aerial photographs. The overlays are then transferred to the OBMs and boundaries can be traced onto the maps. This method is not recommended because of the discrepancy of scales between photographs and OBMs. They can also be transferred mechanically using a Sketchmaster. A Sketchmaster is one of the more common reflection instruments used for manually transferring information from single vertical aerial photographs to maps of a different scale. Boundaries can also be electronically transferred through digitization directly from ortho-rectified aerial photographs (i.e. photographs that have been corrected for distortion). Increasingly, digital aerial photographs on compact discs are being used, providing benefits such as the ability to change scales, and store line files.
  • A dot grid and planimeter are used to calculate land cover area and percentage cover.

Information that must be collected

Data collection during field investigations is critical to accurate identification and mapping of potentially rare vegetation communities. But due to budget and time constraints, staffing expertise, time of year or other variables, it is not always possible to collect all the information outlined in the manual Ecological Land Classification for Southern Ontario: First Approximation and Its Application. Nevertheless, the following information should always be collected during a site visit to a potentially rare community.

  • In forests and woodlands, forest stand characteristics; for other communities, the dominant species of vegetation. A small glass Wedge Prism is used to determine the forest stand composition and basal area of the site. Information about the vegetation composition of a site is mandatory for site classification.
  • Soil characteristics. A soil auger or Oakfield tube is used to sample a soil core to ultimately determine soil texture, depth of organic layer, depth to bedrock, soil moisture, and soil drainage regime of the polygon. This information is also of fundamental importance to the classification system. For example, sugar maple-beech may be a common forest cover type within the planning area, but if it is found on very shallow (e.g., less than 15 cm) sandy soils, it might represent a rare vegetation community.
  • Location of the site and its boundary. This is required for accurate mapping (and protection) of the potentially rare vegetation community.