Back to the Table of Contents

3.2 Ecosystem Units

Figure 3.3

Symbology for Ecosystem Units

Figure 3.4

Example ecosystem map of Dog Creek

3.2.1 Site series Site series is the first component of an ecosystem unit. A list of two-letter codes for all site series currently defined is provided on the TEM website (see Appendix B). Site series codes are unique within a subzone/variant (see Figure 3.5). Generally in forested ecosystems, the first letter of the code refers to the tree species. In all other cases, the codes represent the common names of dominant and/or indicator species.

Figure 3.5

RIC and Ministry of Forests site series codes

Unclassified site units

Additional site series will be developed as inventory and classification of the province continues. These will be for areas that were not well sampled in the initial BEC program, or for particular kinds of ecosystems like grasslands, non-forested wetlands, parkland, and alpine areas. New site series for a particular area must be accepted by the Regional Ecologist of the Ministry of Forests, Forest Sciences Section, before being mapped.

In many projects, plant communities which cannot be identified by the existing site series will be encountered. At the level of sampling being conducted, however, it may not be possible to classify them rigorously through the BEC system. In these cases (e.g., non-forested communities, such as meadows and alpine, as well as high-elevation subalpine forested communities), a more generalized classification will need to be developed for mapping purposes. Broader units will be defined using dominant species and general landscape type (e.g., Mountain-heather-Partridgefoot subalpine meadow). Regional Ecologists of the Ministry of Forests should be consulted for help in defining these units. The new units will be added to the Provincial Site Series Mapping Codes and Typical Environmental Conditions, located on the TEM website (see Appendix B), to ensure correlation between mapping projects.

Combining site series

In some subzones, site series have been defined that may be difficult to distinguish one from another through aerial photograph interpretation. In such cases, the code for the most common site series expected on a particular kind of site should be used, and any other site series that may be defined within the ecosystem unit indicated in the map legend. If actual field sampling allows for confirmation of the site series for specific polygons, then the mapper should indicate in the attribute database part of the "Comments" field that a sample or inspection has been done for that component of the map unit, and that the ecosystem component is confirmed as one or the other site series.

Non-vegetated, sparsely vegetated, and anthropogenic site units

Units that occur in the landscape but are not defined site series, such as rock outcrops, cliffs, talus, urban/suburban areas, cultivated fields, and water bodies, are also mapped using a two-letter code. Standardized codes and definitions for these are listed in Table 3.1, as are site modifiers and structural stages. Some units, such as lakes (LA), will not have site modifiers or structural stages. If a site series code occurs that is the same as one of the codes below, the site series code takes precedence and a new code must be used for the non-vegetated, sparsely vegetated, or anthropogenic unit.

Table 3.1

Codes and definitions for non-vegetated, sparsely vegetated, and anthropogenic units

Code	Ecosystem Unit	Definition	Common Modifiers	Structural Stage
AL	Alkaline Pond	A body of fresh water with a pH greater than 7 and a depth less than 2 m.1	not applicable	not applicable
BA	Barren	Land devoid of vegetation due to extreme climatic or edaphic conditions.1	k, r, w	1
BE	Beach	The area that expresses sorted sediments reworked in recent time by wave action. It may be formed at the edge of fresh or salt water bodies.2	not applicable	1
BF	Blockfields, Blockslopes, Blockstreams	Level or gently sloping areas that are covered with moderately sized or large, angular blocks of rock derived from the underlying bedrock or drift by weathering and/or frost heave, and that have not undergone any significant downslope movement.1	k, r, w	1
CA	Canal	An artificial watercourse created for transport, drainage, and/or irrigation purposes	not applicable	not applicable
CB	Cutbank	A part of a road corridor or river course situated upslope of the road or river, which is created by excavation and/or erosion of the hillside.2	k, w	1

Code	Ecosystem Unit	Definition	Common Modifiers	Structural Stage
CF	Cultivated Field	A flat or gently rolling, non-forested, open area that is subject to human agricultural practices (including plowing, fertilization and non-native crop production) which often result in long-term soil and vegetation changes.	not applicable	1, 2, 3
CL	Cliff	A steep, vertical or overhanging rock face.3	q, z	1
CO	Cultivated Orchard	An agricultural area composed of single or multiple tree species planted in rows. Pruning maintains low, bushy trees.	not applicable	3
CV	Cultivated Vineyard	An agricultural area composed of single or multiple species of grapes planted in rows, usually supported on wood or wire trellises.	not applicable	3
ES	Exposed Soil	Any area of exposed soil that is not included in any of the other definitions. It includes areas of recent disturbance, such as mud slides, debris torrents, avalanches, and human-made disturbances (e.g., pipeline rights-of-way) where vegetation cover is less than 5%.2	k, r, w	1
GB	Gravel Bar	An elongated landform generated by waves and currents and usually running parallel to the shore. It is composed of unconsolidated small rounded cobbles, pebbles, stones, and sand.	not applicable	1
GC	Golf Course	Flat to gently rolling grass-covered throughways and open areas set out for the playing of golf. The fairways are usually separated by isolated rows or patches of trees, shrubs and small bodies of water (forested areas and water bodies to be mapped as separate units).	not applicable	2-7
GL	Glacier	A mass of perennial snow and ice with definite lateral limits. It typically flows in a particular direction.2	not applicable	not applicable
GP	Gravel Pit	An area exposed through the removal of sand and gravel.2	k,w	1
LA	Lake	A naturally occurring static body of water, greater than 2 m deep in some portion. The boundary for the lake is the natural high water mark.2	not applicable	not applicable
LB	Lava Bed	An area where molten rock has flowed from a volcano or fissure and cooled to form solidified rock.2	k, r, w	1

Code	Ecosystem Unit	Definition	Common Modifiers	Structural Stage
MI	Mine	An unvegetated area used for the extraction of mineral ore and other materials.1	not applicable	1
MO	Moraine	An unvegetated landform consisting of unstratified glacial drift that is usually till and taking a variety of shapes, ranging from plains to mounds and ridges that are initial forms independent of underlying bedrock or older materials.4	k, w	1
MS	Rubbly Mine Spoils	Discarded overburden or waste rock moved so that ore can be extracted in a mining operation.2	not applicable	1
MU	Mudflat Sediment	Flat plain-like areas dominated by fine-textured sediments. These areas are found in association with freshwater, saltwater or estuarine bays (at low tide), lakes, ponds, rivers and streams.2	not applicable	1
OW	Shallow Open Water	A wetland composed of permanent shallow open water and lacking extensive emergent plant cover. The water is less than 2 m deep. (If vegetated, these units should developed into site series groups for interpretation.)	not applicable	not applicable
PD	Pond	A small body of water greater than 2 m deep, but not large enough to be classified as a lake (e.g., less than 50 ha).	not applicable	not applicable
PG	Patterned Ground	An unvegetated land surface with a distinctive arrangement of stones or microtopography due to the effects of ground freezing and seasonal frost.1	not applicable	1
PS	Permanent Snow	Snow or ice that is not part of a glacier but is found during summer months on the landscape.2	not applicable	not applicable
RE	Reservoir	An artificial basin created by the impoundment of water behind a human-made structure such as a dam, berm, dyke, or wall.2	not applicable	not applicable
RG	Rock Glacier	A tongue-shaped or lobate, ridged accumulation of angular fragments containing interstitial ice. These areas, which move slowly downslope, are morphologically similar to glaciers.1	k, w	1
RI	River	A watercourse formed when water flows between continuous, definable banks. The flow may be intermittent or perennial. An area that has an ephemeral flow and no channel with definable banks is not considered a river.2	not applicable	not applicable

Code	Ecosystem Unit	Definition	Common Modifiers	Structural Stage
RM	Reclaimed Mine	A mined area that has plant communities composed of a mixture of agronomic or native grasses, forbs, and shrubs.	k, r, w	1, 2, 3
RN	Railway Surface	A roadbed with fixed rails for possibly single or multiple rail lines.2	not applicable	not applicable
RO	Rock Outcrop	A gentle to steep, bedrock escarpment or outcropping, with little soil development and sparse vegetative cover.	k, r, w	1
RP	Road Surface	An area cleared and compacted for the purpose of transporting goods and services by vehicles.2	not applicable	not applicable
RR	Rural	Any area in which residences and other human developments are scattered and intermingled with forest, range, farm land, and native vegetation or cultivated crops. (Forested areas and cultivated fields should be mapped as separate units.)1	not applicable	not applicable
RU	Rubble	Rubble is common on the ground surface in and adjacent to alpine areas, on ridgetops, gentle slopes and flat areas due to the effects of frost heaving.2, 4	k, r, w	1
SW	Saltwater	Any body of water that contains salt or is considered to be salty.2	not applicable	not applicable
TA	Talus	Angular rock fragments of any size accumulated at the foot of steep rock slopes as a result of successive rock falls. It is a type of colluvium.2, 4	k, r, w	1
TS	Mine Tailings	Solid waste materials directly produced in the mining and milling of ore.2	not applicable	1
UR	Urban/ Suburban	An area in which residences and other human developments form an almost continuous covering of the landscape. These areas include cities and towns, subdivisions, commercial and industrial parks, and similar developments both inside and outside city limits. (Forested areas, such as parks, should be mapped as separated units.)1	not applicable	not applicable

¹ Dunster and Dunster (1996)
² Resources Inventory Committee (1997a)
³ Sinnemann (1992)
⁴ Howes and Kenk (1997)

3.2.2 Site modifiers

Each site series within the Ministry of Forests biogeoclimatic ecosystem classification has been described by a "typical" set of environmental conditions focusing specifically on important site, soils, and terrain characteristics (see Provincial Site Series Mapping Codes and Typical Environmental Conditions TEM website in Appendix B). The variation within some site series may be well described by the typical conditions; for others, the typical conditions may describe only one possible set. In TEM, site modifiers (presented in Table 3.2) are used to describe these atypical conditions for each ecosystem. Site modifiers provide additional descriptors for an ecosystem, and, if applicable, are displayed as the second component of an ecosystem unit.

Table 3.2

Site modifiers for atypical conditions

Code

Criteria

Topography

a	active floodplain1 - the site series occurs on an active fluvial floodplain (level or very gently sloping surface bordering a river that has been formed by river erosion and deposition), where evidence of active sedimentation and deposition is present.
g	gullying1 occurring - the site series occurs within a gully, indicating a certain amount of variation from the typical, or the site series has gullying throughout the area being delineated.
h	hummocky1 terrain (optional modifier) - the site series occurs on hummocky terrain, suggesting a certain amount of variability. Commonly, hummocky conditions are indicated by the terrain surface expression but occasionally they occur in a situation not described by terrain features.
j	gentle slope - the site series occurs on gently sloping topography (less than 25% in the interior, less than 35% in the CWH, CDF, and MH zones).
k	cool aspect - the site series occurs on cool, northerly or easterly aspects (285o-135o), on moderately steep slopes (25%-100% slope in the interior and 35%-100% slope in the CWH, CDF and MH zones).
n	fan1 - the site series occurs on a fluvial fan (most common), or on a colluvial fan or cone.

Code	Criteria
q	very steep cool aspect - the site series occurs on very steep slopes (greater than 100% slope) with cool, northerly or easterly aspects (285o-135o).
r	ridge1(optional modifier) - the site series occurs throughout an area of ridged terrain, or it occurs on a ridge crest.
t	terrace1 - the site series occurs on a fluvial or glaciofluvial terrace, lacustrine terrace, or rock cut terrace
w	warm aspect - the site series occurs on warm, southerly or westerly aspects (135o-285o), on moderately steep slopes (25%-100% slope in the interior and 35%-100% slope in the CWH, CDF and MH zones)
z	very steep warm aspect - the site series occurs on very steep slopes (greater than 100%) on warm, southerly or westerly aspects (135o-285o).

Moisture

x

drier than typical (optional modifier) - describes part of the range of conditions for circummesic ecosystems with a wide range of soil moisture regimes or significantly different site conditions. For example, SBSmc2/01 (Sxw-Huckleberry) has three site phases described, and the submesic phase can be labeled with the "drier than average" modifier (e.g., SBx). This code should be applied only after consultation with the Regional Ecologist.

y

moister than typical (optional modifier) - describes part of the range of conditions for circummesic ecosystems with a wide range of soil moisture regimes or significantly different site conditions. For example, SBSmk1/06 (Sb-Huckleberry-Spirea) is "typically" described as submesic to mesic. When this site series is found on subhygric or hygric sites, the "y" modifier is used (e.g., BHy). This code should be applied only after consultation with the Regional Ecologist.

Soil

c	coarse-textured soils2 - the site series occurs on soils with a coarse texture, including sand and loamy sand; and also sandy loam, loam, and sandy clay loam with greater than 70% coarse fragment volume.
d	deep soil - the site series occurs on soils greater than 100 cm to bedrock
f	fine-textured soils2 - the site series occurs on soils with a fine texture including silt and silt loam with less than 20% coarse fragment volume; and clay, silty clay, silty clay loam, clay loam, sandy clay and heavy clay with with less than 35% coarse fragment volume.
m	medium-textured soils - the site series occurs on soils with a medium texture, including sandy loam, loam and sandy clay loam with less than 70% coarse fragment volume; silt loam and silt with more than 20% coarse fragment volume; and clay, silty clay, silty clay loam, clay loam, sandy clay and heavy clay with more than 35% coarse fragment volume.
p	peaty material - the site series occurs on deep organics or a peaty surface (15-60 cm)3 over mineral materials (e.g., on organic materials of sedge, sphagnum, or decomposed wood).
s	shallow soils - the site series occurs where soils are considered to be shallow to bedrock (20-100 cm).
v	very shallow soils - the site series occurs where soils are considered to be very shallow to bedrock (less than 20 cm).

¹ Howes and Kenk 1997
² Soil textures have been grouped specifically for the purposes of ecosystem mapping.
³ Canada Soils Survey Committee, 1987

Figure 3.6

Use of site modifiers in mapping site series

3.2.3 Vegetation developmental units

Structural stage numbers (Table 3.3) must be indicated for each ecosystem unit (including non-forested units) except as noted in Table 3.1. Additional substages are used to further differentiate structural stages 1 through 3 according to life form, layers and relative cover of individual strata. Substages 1a, 1b and 2a-d should be used if photo interpretation is possible, otherwise, stage 1 and 2 should be used. Substages 3a, and 3b should be used for permanent shrub communities (e.g., krummholz), and for detailed mapping projects where this differentiation is required for interpretations. Structural stages and substages are described in Table 3.3.

Table 3.3

Structural stages and codes1

Structural Stage

Description

Post-disturbance stages or environmentally induced structural development

1 Sparse/bryoid2	Initial stages of primary and secondary succession; bryophytes and lichens often dominant, can be up to 100%; time since disturbance less than 20 years for normal forest succession, may be prolonged (50-100+ years) where there is little or no soil development (bedrock, boulder fields); total shrub and herb cover less than 20%; total tree layer cover less than 10%.
Substages 1a Sparse2	Less than 10% vegetation cover;
1b Bryoid2	Bryophyte- and lichen-dominated communities (greater than 1/2 of total vegetation cover).

Stand initiation stages or environmentally induced structural development

2 Herb2

Early successional stage or herbaceous communities maintained by environmental conditions or disturbance (e.g., snow fields, avalanche tracks, wetlands, grasslands, flooding, intensive grazing, intense fire damage); dominated by herbs (forbs, graminoids, ferns); some invading or residual shrubs and trees may be present; tree layer cover less than 10%, shrub layer cover less than or equal to 20% or less than 1/3 of total cover, herb-layer cover greater than 20%, or greater than or equal to 1/3 of total cover; time since disturbance less than 20 years for normal forest succession; many herbaceous communities are perpetually maintained in this stage.

Substages

2a Forb-dominated2	Herbaceous communities dominated (greater than 1/2 of the total herb cover) by non-graminoid herbs, including ferns.
2b Graminoid-dominated2	Herbaceous communities dominated (greater than 1/2 of the total herb cover) by grasses, sedges, reeds, and rushes.
2c Aquatic2	Herbaceous communities dominated (greater than 1/2 of the total herb cover) by floating or submerged aquatic plants; does not include sedges growing in marshes with standing water (which are classed as 2b).
2d Dwarf shrub2	Communities dominated (greater than 1/2 of the total herb cover) by dwarf woody species such as Phyllodoce empetriformis, Cassiope mertensiana, Cassiope tetragona, Arctostaphylos arctica, Salix reticulata, and Rhododendron lapponicum. (See list of dwarf shrubs assigned to the herb layer in the Field Manual for Describing Terrestrial Ecosystems).

3 Shrub/Herb3

Early successional stage or shrub communities maintained by environmental conditions or disturbance (e.g., snow fields, avalanche tracks, wetlands, grasslands, flooding, intensive grazing, intense fire damage); dominated by shrubby vegetation; seedlings and advance regeneration may be abundant; tree layer cover less than 10%, shrub layer cover greater than 20% or greater than or equal to 1/3 of total cover.

Structural Stage

Description

Substages 3a Low shrub3	Communities dominated by shrub layer vegetation less than 2 m tall; may be perpetuated indefinitely by environmental conditions or repeated disturbance; seedlings and advance regeneration may be abundant; time since disturbance less than 20 years for normal forest succession.
3b Tall shrub3	Communities dominated by shrub layer vegetation that are 2-10 m tall; may be perpetuated indefinitely by environmental conditions or repeated disturbance; seedlings and advance regeneration may be abundant; time since disturbance less than 40 years for normal forest succession.

Stem exclusion stages

4 Pole/Sapling4

Trees greater than 10 m tall, typically densely stocked, have overtopped shrub and herb layers; younger stands are vigorous (usually greater than 10-15 years old); older stagnated stands (up to 100 years old) are also included; self-thinning and vertical structure not yet evident in the canopy - this often occurs by age 30 in vigorous broadleaf stands, which are generally younger than coniferous stands at the same structural stage; time since disturbance is usually less than 40 years for normal forest succession; up to 100+ years for dense (5000-15 000+ stems per hectare) stagnant stands.

5 Young Forest4

Self-thinning has become evident and the forest canopy has begun differentiation into distinct layers (dominant, main canopy, and overtopped); vigorous growth and a more open stand than in the pole/sapling stage; time since disturbance is generally 40-80 years but may begin as early as age 30, depending on tree species and ecological conditions.

Understory reinitiation stage

6 Mature Forest4

Trees established after the last disturbance have matured; a second cycle of shade tolerant trees may have become established; understories become well developed as the canopy opens up; time since disturbance is generally 80-140 years for biogeoclimatic group A5 and 80-250 years for group B.6

Old-growth stage

7 Old Forest4

Old, structurally complex stands composed mainly of shade-tolerant and regenerating tree species, although older seral and long-lived trees from a disturbance such as fire may still dominate the upper canopy; snags and coarse woody debris in all stages of decomposition typical, as are patchy understories; understories may include tree species uncommon in the canopy, due to inherent limitations of these species under the given conditions; time since disturbance generally greater than 140 years for biogeoclimatic group A5 and greater than 250 years for group B.6

1	In the assessment of structural stage, structural features and age criteria should be considered together. Broadleaf stands will generally be younger than coniferous stands belonging to the same structural stage.
2	Substages 1a, 1b and 2a-d should be used if photo interpretation is possible, otherwise, stage 1 and 2 should be used.
3	Substages 3a and 3b may, for example, include very old krummholz less than 2 m tall and very old, low productivity stands (e.g., bog woodlands) less than 10 m tall, respectively. Stage 3, without additional substages, should be used for regenerating forest communities that are herb or shrub dominated, including shrub layers consisting of only 10-20% tree species, and undergoing normal succession toward climax forest (e.g., recent cut-over areas or burned areas).
4	Structural stages 4-7 will typically be estimated from a combination of attributes based on forest inventory maps and aerial photography. In addition to structural stage designation, actual age for forested units can be estimated and included as an attribute in the database, if required.
5	Biogeoclimatic Group A includes BWBSdk, BWBSmw, BWBSwk, BWBSvk, ESSFdc, ESSFdk, ESSFdv, ESSFxc, ICHdk, ICHdw, ICHmk1, ICHmk2, ICHmw3, MS (all subzones), SBPS (all subzones), SBSdh, SBSdk, SBSdw, SBSmc, SBSmh, SBSmk, SBSmm, SBSmw, SBSwk1 (on plateau), and SBSwk3
6	Biogeoclimatic Group B includes all other biogeoclimatic units (see Appendix C)

Structural stage modifiers (optional attribute) are used when required for further differentiation of structural stages 3 to 7. These modifiers describe five stand structure types based on the relative development of overstory, intermediate, and suppressed crown classes (Table 3.4, Figure 3.7).

Table 3.4

Structural stage modifiers1 and codes2

Modifier

Description

s	single storied	Closed forest stand dominated by the overstory crown class (dominant and co-dominant trees); intermediate and suppressed trees account for less than 20% of all crown classes combined3; advance regeneration in the understory is generally sparse.
t	two storied	Closed forest stand co-dominated by distinct overstory and intermediate crown classes; the suppressed crown class is lacking or accounts for less than 20% of all crown classes combined3; advance regeneration is variable.
m	multistoried	Closed forest stand with all crown classes well represented; each of the intermediate and suppressed classes account for greater than 20% of all crown classes combined3; advance regeneration is variable
i	irregular	Forest stand with very open overstory and intermediate crown classes (totaling less than 30% cover), and well-developed suppressed crown class; advance regeneration is variable.
h	shelterwood	Forest stand with very open overstory (less than 20% cover) and well-developed suppressed crown class and/or advance regeneration in the understory; intermediate crown class is generally absent.

1	Adapted from Weetman et al. (1990). Stand structure types and crown classes are further described and illustrated in Figure 3.7.
2	Structural stage modifiers should be used as in the following examples: 5s for young forest stage with single-storied structure or 7m for old forest with multistoried structure. The only structural stage modifier, other than single storied, generally applicable to structural stage 3 is "h" (for shelterwood). This can be used to describe recently regenerated stands with a very open overstory (less than 20% cover of mature trees or vets) and a (usually dense) understory of seedlings and saplings.
3	Based on either basal area or percent cover estimates.

Figure 3.7

Structural stage modifiers

Stand composition modifiers (optional attribute) are used as required for further differentiation of structural stages 3 to 7. These modifiers differentiate coniferous, broadleaf, and mixed stands (Table 3.5).

Table 3.5	Stand composition modifiers1, 2 and codes
Modifier		Description

C	coniferous	Greater than 3/4 of total tree layer cover3 is coniferous
B	broadleaf	Greater than 3/4 of total tree layer cover3 is broadleaf
M	mixed	Neither coniferous or broadleaf account for greater than 3/4 of total tree layer cover3

1	Adapted from RIC, 1997a
2	Stand composition modifiers should be used as in the following examples: 6C for mature forest of coniferous composition, 7mM for old forest with multistoried structure and mixed composition, 3bC for tall shrub community dominated by coniferous saplings.
3	Stand composition modifiers emphasize overstory and intermediate tree layers, since these are the most visible on aerial photographs.

Seral community types¹ (optional attribute)

Seral community types (Table 3.6) are an optional ecosystem attribute that should only be used in mapping where project objectives and survey intensity level warrant this level of detail. For instance, if seral floristic differences are relevant (as, for example, in the assessment of forage species or competing vegetation complexes) a floristic classification of seral community types may be required in a mapping project. A description of seral plant communities is useful for determining where the current plant community falls on the scale between early seral and potential natural community climax for any community type. (Province of BC, 1995b).

Given lack of data on seral ecosystems, there is not a current standard list of seral community types for the province. Therefore, classification and mapping of seral community types must be approved by the Regional Ecologist during a mapping project. This will help to ensure some degree of standardization and correlation of seral units as they are proposed. A list of currently used seral community types and their codes is being maintained with the Provincial Site Series Mapping Codes and Typical Environmental Conditions on the TEM website (see Appendix B). Seral community types are named using two or three typical or dominant species (e.g., trembling aspen-creamy peavine), and are given a two-letter lower-case code (e.g., ap).

1	We limit the term "seral" here to the developmental stages of an ecological succession not including the climax community (Lincoln et al., 1982). We recognize that, in the ecological literature, climax communities are also technically considered part of the sere.

Table 3.6

Example seral community types for the BWBSmw2

Seral Community Code

Seral Community Name (DeLong, 1988)

ap	At - creamy peavine
ak	At - kinnikinnick
as	At - soopolallie
la	At - Labrador tea
ab	At - black twinberry
ao	At - oak fern
ac	Ac - cow parsnip

3.2.4

Alternate methods for assigning site modifiers and structural stage

Site modifiers are usually estimated from air photographs. However, an alternative to interpreting these attributes is to model them from existing digital data sources. For example, TRIM data can be used to determine aspect modifiers and terrain attributes could be used to assign certain other site modifiers. Modelling is acceptable if it provides results similar to air photo interpretation.

Similarly, structural stage, structural stage modifiers, and stand composition modifiers are usually estimated from air photos. Alternatively, the forest cover database (specifically the age, species composition, and stocking criteria) is a useful source of information for assigning these attributes. In fact, it should be possible, using this database in combination with some field verification, to model structural stage for a given study area and assign structural stage to ecosystem polygons using GIS programming algorithms. Modelling of a dynamic attribute such as structural stage may better facilitate future updates from the forest cover mapping. However, modelling requires expertise and software that may not be readily available to all mapping contractors. Where modelling of structural stage is used, it may be preferable for interpretations to keep it as a separate layer within the GIS.

3.2.5 Naming ecosystem units

[Back to TOC] [Previous] [Next]