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Biogeoclimatic Ecosystem Classificationa Natural System for Ecosystem-Based
Land Management1
Donald S. McLennan 2
Abstract-This paper puts forward the thesis that, in order to
produce useful ecological inventory approaches that satisfy the
requirement for integration at different scales and between different ecosystem components, the integration of ecosystem properties must occur as a fundamental component of the map units, i.e.,
as a part of the classification system. Other ecosystem components
can be related to the integrated ecosystem classification following
delineation of the basic ecosystem units. This presentation demonstrates this approach using Biogeoclimatic Ecosystem Classification (Pojar et al. 1987) concepts in three watersheds in coastal
British Columbia.
The approach ofthe Biogeoclimatic Ecosystem Classification is to
utilize phyto-sociological concepts to interpret and classify ecosystems. Plant community-derived ecosystem classes are then related
to physical environmental components based on detailed field
descriptions of site and soil properties. In this way the integration
of the complex of environmental factors is interpreted for three
fundamental properties---climate, soil moisture, and soil nutrients.
Using this approach, biologically-significant boundaries in regional
and local ecological gradients can be identified and used to link the
classification to the landscape. The same approach is used to derive
classes for ecosystem succession with the site classification. In
British Columbia, regional (Biogeoclimatic Zones, Subzones, and
Variants), local (Site Associations, Site Series and Site Types), and
chronological (Seral Associations) scale ecosystems have been classified within a hierarchical framework. The result is a natural
(taxonomic) classification that can be interpreted for a wide range
of purposes, including wildlife capability and suitability, forest
productivity (site index), forest health, soil conservation, riparian
management, and biodiversity inventory.
This presentation demonstrates the Biogeoclimatic Ecosystem
Classification approach to ecosystem inventory by reporting on the
Greater Vancouver Regional District Ecosystem Inventory presently being carried out in three 20,000 ha watersheds that provide
drinking water to the city of Vancouver, Canada. The project has
been ongoing for about 5 years, and has involved a team of scientists
including a hydrologist, terrain scientist, ecologist, forest inventory
specialist, forest health specialist, and forest fire specialist. Complete, inter-related inventories of these watersheds have been
completed and maps will show interpretations derived from the
different ecosystem components. The inventory is linked to a landscape model, which as a number of inter-related components,
including sediment recruitment and delivery, landslides and soil
erosion, forest succession, forest pests, and forest fire hazard. The
Ipaper presented at the North American Science Symposium: Toward a
Unified Framework for Inventorying and Monitoring Forest Ecosystem
Resources, Guadalajara, Mexico, November 1-6, 1998.
2Donald S. McLennan is President, Oikos Ecological Services Ltd., 3855 2nd
Avenue, PO Box 985, Smithers, British Columbia, Canada. VOJ 2NO. Phone:
(250) 847-1946; Fax: (250) 847-1948; e-mail: oikdon@bulkley.net; webpage:
www.hiway16.comloikos
USDA Forest Service Proceedings RMRS-P-12. 1999
model is being used in conjunction with the ecological inventory to
compare the impacts on water quality and biodiversity of three
different management options over a 200 year planning horizon.
The model and inventory is used to compare, for the three management approaches, water quality impacts (changes in annual fine
sediment delivery to the reservoir) of potential watershed disturbances, including a large fire and a major insect outbreak. Future
work involves determining the applicability of the model for deriving global warming effects, and the long term impacts of air
pollution on water quality and ecosystem resources.
Resumen-Este articulo sostiene la tesis que para producir
inventarios ecol6gicos utiles que satisfagan los requerimientos para
la integraci6n a diferentes escalas y entre diferentes componentes
de los ecosistemas, la integraci6n de las propiedades de los ecosistemas debe ocurrir como un componente fundamental de las unidades
mapeadas, es decir, como una parte del sistema de clasificaci6n.
Otros componentes del ecosistema pueden ser relacionados como un
sistema de clasificaci6n integrado, siguiendo la delineaci6n de las
unidades basicas del ecosistema. La presentaci6n demuestra este
enfoque usando los conceptos de la clasificaci6n biogeoclimatica de
los ecosistemas (Pojar et al. 1987) En tres cuencas de la costa de
Columbia Britanica.
Este enfoque utiliza conceptos fitosociol6gicos para interpretar y
clasificar los ecosistemas. Las comunidades vegetales clasificadas
se relacionan a los componentes ambientales fisicos basados en
descripciones detalladas de campo. En esta forma la integraci6n del
complejo ambiental se interpreta por tres propiedades fundament ales: clima, humedad del suelo y nutrientes del suelo. Usando este
enfoque los limites biol6gicamente significativos en gradientes
ecol6gicos regionales 0 locales pueden ser identificados y us ados
para la clasificaci6n del paisaje. El mismo enfoque se utiliza para
derivar clases sucesionales con la clasificaci6n de sitios. Las escalas
del ecosistema han sido clasificado de manerajerarquica en Columbia Britlinica: regionales (zonas y subzonas biogeoclimaticas), locales (asociaciones de sitio, series de sitio y tipos de sitio) y cronologias
(asociaciones serales).
El resultado es una clasificaci6n natural (taxon6mica) que puede
ser interpretada para una amplia gama de prop6sitos, incluyendo
capacidad de vida silvestre y sostenibilidad, productividad forestal
(indice de sitio), salud del bosque, conservaci6n del suelo, manejo de
areas riparias e inventarios de biodiversidad.
Esta presentaci6n demuestra el enfoque de la clasificaci6n
biogeoclimatica de los ecosistemas al inventario de los ecosistemas
del mayor distrito regional de Vancouver, llevandose a cabo en tres
cuencas que abarcan 20 000 ha, las cuales proporcionan agua
potable ala ciudad de vancouver. El proyecto ha sido continuado por
aproximadamente 5 a:iios, y ha involucrado un equipo de cientificos
incluyendo un hidr610go, un edafologo, un ec610go, un especialista de
inventarios forestales, un pat610go forestal y un especialista en
incendios forestales. Inventarios completos de estas cuencas han
319
sido mapeados y mostraran las interpretaeiones derivadas de los
diferentes eomponentes de los ecosistemas. El inventario esta ligado
a un modelo del paisaje, el eual tiene un nu.mero de eomponentes
inter-relaeionados, incluyendo reclutamiento de sedimentos, erosi6n delsuelo, sucesi6n forestal, plagas forestales e ineendios forestales. El modelo esta siendo usado en eonjunei6n con el inventario
eeo16gieo para eomparar los impaetos de la ealidad del agua y la
biodiversidad de tres diferentes opeiones de manejo sobre un horizonte de planeaei6n de 200 anos.
Sustainable land management requires an ecosystembased system for ecosystem inventory, for describing ecosystem processes, and for developing effective management
approaches that account for a wide range of extractive and
non-extractive values. A fundamental prerequisite for a
useful ecosystem-based land management system should be
its ability to integrate physiography, surficial materials,
soils, vegetation and animal ecosystem components in a
meaningful manner that identifies important ecosystem
processes. This report shows how the Biogeoclimatic Ecosystem Classification achieves these objectives.
BEC is an ecosystem-based land management system
that has been developed over the last 50 years in British
Columbia, and has been used for a range of resource applications. This report outlines the historical development of
BEC, explains the theory and methods employed by the
system, describes Terrestrial Ecosystem Mapping, and reviews applications of BEC. The report emphasizes that the
unique value of BEC is its ability to provide ecosystem
integration as an integral component of the classification
approach. BEC links physiographic and biological ecosystem components and integrates them to provide a powerful
tool for ecosystem-based land management.
Development of Biogeoclimatic
Ecosystem Classif~cation _ _ __
Biogeoclimatic Ecosystem Classification (BEC) is a system of classification developed and widely used by land
managers in British Columbia, Canada. The scientific foundations of BEC are grounded in the research of Vladamir
Krajina and his graduate students at the University of
British Columbia. Between 1949 and 1975 Dr. Krajina and
his students carried out the original descriptions of forest
ecosystems across the diverse physiographic and climatic
regions of British Columbia. In 1975 the approach was
adopted by the British Columbia Forest Service, and, between 1975 and 1985, what had been a principally academic
system was translated into operational methodologies that
are now applied by technical and professional land managers across the province. These are described in a series of
regional ecosystem guides that specifically describe all
sub zones and site series in each of British Columbia's six
administrative forest regions.
Overview of the System
Biogeoclimatic Ecosystem Classification (BEC) is described
as a natural, wholistic ecosystem classification approach.
320
BEC is a natural system because classification is based on
the essential properties that characterize ecosystems - climate, soil moisture and soil nutrients. This is in contrast to
interpretative classifications that classify landscape units
for particular purposes, such as for interpreting forest productivity or wildlife habitat attributes for a particular animal species. Because it is a natural cla~sification system, it
is very useful for developing a range of interpretations, all
of which will have a basis in an integrated ecosystem
classification.
BEC is an wholistic system because it uses interpretations
of plant indicator species distributions to integrate the
complex of environmental factors that interact at a range of
scales to produce a complex mosaic of ecosystems across the
landscape. More specifically, phytosociological analysis of
plant communities in specific kinds of ecosystems is used as
a bioindicator to produce specific interpretations of climate,
soil moisture, and soil nutrients. BEC uses phytosociological
principles to identify biologically-meaningful segments of
the landscape at three levels - regional, local, and chronological (Table 1).
The Regional Level
Regional ecosystems are biogeoclimatic zones, subzones
and variants, and represent geographic areas with relatively uniform regional climates. The classification of
biogeoclimatic subzones is determined by phytosociological
analysis of mature plant communities on zonal sites. Zonal
sites are characterized by having a moderate slope without
a significant aspect effect, have medium-textured, moderate
to deep soils without a high component of coarse fragments,
and are medium in terms of the availability of moisture and
nutrients. Sites with these characteristics are expected to
provide the best bioindication of regional climatic effects,
and differences revealed by phytosociological analysis of
mature and old forest plant communities on zonal sites are
interpreted to reflect biologically significant segments of
the regional climatic gradients.
The Local Level
The local ecosystem level identifies site series, site associations, and site types to provide a classification of ecologically-equivalent sites within regional climates, i.e., within
biogeoclimatic sub zones and variants. As for the regional
level, the classification of site series at the local level is
developed using phytosociological analysis of mature and
old forest plant communities to identify biologically-significant segments of mesoscale soil moisture and soil nutrient
gradients. The site series classified within a subzone or
variant are organized on an edatopic grid with relative soil
moisture regime (0-8) on the Y axis, and relative soil nutrient regime (very poor, poor, medium, rich, and very rich) on
the X axis. In this way the site series for a sampled ecosystem
can be determined regardless of successional stage of the
ecosystem using site quality analysis (see Site Description
and Identification), which identifies soil moisture-soil nutrient regime combinations.
Site series may occur on a range of landforms and landscape positions, but the effect of compensating factors will
USDA Forest Service Proceedings RMRS-P-12. 1999
result in ecological equivalence, as expressed by membership in the same plant association in the mature and old
forest successional stage. For example, a site with coarse
soils and constant seepage at the base of a long slope may be
identified as having the same site quality as a level site with
fine textured soils and fluctuating water table. These two
sites, although morphologically distinct, would be included
in the same site series, but identified as unique site types.
Thus site series are divided into site types to account for
differences in site morphological features.
The ecological equivalence of site series implies a similar
vegetation potential within classification units. Thus it is
expected that, for a given site series, similar plant communities will develop over time as forest succession proceeds.
As a result, the site series classification provides a meaningful ecological template for describing and predicting ecosystem succession (see The Chronological Level).
Another important aspect of the site series classification
is that ecosystems included within the same site series will
have similar productivity. This is well demonstrated by the
close correlation that has been demonstrated between site
series and the site index of the commercial tree species
(FRBCIMOF 1997). This correlation is presently being used
to adjust growth and yield estimates for operational tenures
in British Columbia. The close correlation between site
series and site index suggests that the site series classifica-
tion of BEC is successful in dividing the landscape into
ecologically equivalent segments.
The Chronological Level
The third level of classifica tion in BEC is the chronological
level and, in general, very little work has been carried out for
this component of the classification. Klinka et al. (1987)
demonstrated the application of the approach for successional forest ecosystems in Coastal British Columbia. Seral
associations of seral deciduous ecosystems in north western
British Columbia were described by Oikos (1998e). Seral
associations are classified by phytosociological analysis of
seral ecosystems along forest successional chronosequences.
Stand structural stages (Table 2) describe ecologicallysignificant changes in stand structural characteristics along
the continuum of stand developmen t from stand ini tia tion to
old forest, following the general approach proposed by
Hamilton (1988) and Oliver and Larson (1990). Stand structural stages are not defined floristically, as are other BEC
classification units, but are intended to classify the main
stand development processes that occur over the course of
forest succession. Two stand structural stages will often
incorporate a single seral association, especially during the
middle stages of stand development.
Table 1.-0verview of the three levels of the Biogeoclimatic Ecosystem Classification system, showing approach to classification, ecosystem
identification, and ecosystem mapping.
Level
Objective
Classification
Identification
Mapping
Regional
classification of
regional climates
Subzones are delineated by
vegetation classification of
mature ecosystems on
zonal sites 1 ; subzones are
agglomerated into Zones,
and divided into Variants.
Subzones are identified by
the evaluation of those plant
indicator species that identify
the zonal plant association in
mature zonal ecosystems.
Subzone boundaries are
mapped based on ground
evaluations that describe
and compare climatic
indicator species in mature
zonal ecosystems along
climatic gradients.
Local
classification of
ecologically
equivalent sites
within regional
climates
Site Series are delineated
by vegetation classification
of mature ecosystems on
azonal sites2 . A site series
is a group of sites within a
regional climate (subzone or
variant) with a similar vegetation potential. Site series
are agglomerated into Site
Associations where they occur
in different subzones, and
divided into Site Types where
they differ in landform and/or
physical characteristics within
subzones.
Site series are identified
through site quality analysis.
This involves two parallel
evaluations: an interpretation
of plant indicator species and
an evaluation of site and soil
factors. These two evaluations
are compared to evaluate site
quality and determine site series.
Site series mapping is the core
of ecosystem mapping and is
carried out on air photos by
inferring site series from an
integrationof surficial materials,
geomorphic processes, mesoscale slope position, and
vegetation characteristics.
Chronological
classification
of successional
ecosystems
within site
series
Seral Associations are delineated
by vegetation classification of
successional ecosystems along
a chronosequence. Seral associations usually include more than
one structural stage (see Table 2).
Seral associations are identified
by the evaluation of those plant
indicator species that ·identify
the seral association.
Mapping is carried out as
a component of ecosystem
mapping by evaluating plant
community characteristics
for a site series polygon.
1 zonal sites are a subset of mesic sites, and are characterized by having a moderate slope without a significant aspect effect, medium textured, deep soils without
a high component of coarse fragments; in mountainous areas they are located in middle mesoslope positions,
2azonal sites include all sites not defines as zonal
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321
Table 2a.-8tand structural stages used in Terrestrial Ecosystem Mapping (RIC 1998) to describe changes in stand characteristics along the
forest successional continuum.
Stand Structural Stages
Code
Structural Stage
Definition
Non-vegetated Sparse
Initial stages in primary or secondary succession. Little or no residual vegetation except for bryophytes
and lichens. <20 years since disturbance for normal forest succession; may be prolonged (50-100 yrs+)
where there is little or no soil development.
1a
Non-vegetated
less than 5% total cover of vegetation;
1b
Sparse
less than 10% cover of vascular plants;
1c
Bryoid
bryophyte and lichen dominated communities >50% cover; shrub and herb cover <20%; tree cover <10%.
2
Herb
Early successional stage or self maintained structure due to environmental conditions or disturbance
(e.g., avalanche tracks, wetlands and grasslands); dominated by herbaceous vegetation. Tree cover
<10%, shrub cover <20; time since disturbance <20 yrs for normal forest succession. Includes 2a forbdominated, 2b graminoid dominated, 2c aquatic, 2d dwarf shrubs.
3
Shrub
Early successional stage or disclimax / climax communities dominated by shrubby vegetation <10m
tall. Seedlings and advance regeneration may be abundant. Tree cover <10%, shrub cover >25%. Time
since disturbance <20 yrs for normal forest succession.
3a
Low Shrub
Shrubby vegetation <2 m tall.
3b
Tall Shrub
Shrubby vegetation 2-10 m tall.
4
Pole / Sapling
Trees> 10m tall, have overtopped shrub and herb layers and stands are typically dense; younger
stands are vigorous, older pole-sapling stages composed of dense, stagnated stands (<1 00 yrs) are
included in this stage. This stage persists until self-thinning and canopy differentiation becomes
evident. Time since last disturbance < yrs for normal forest succession.
5
Young Forest
Self-thinning has become evident and the forest canopy has begun differentiation into distinct layers
(dominant, main canopy, and overtopped). 40-80 yrs since last disturbance.
6
Mature Forest
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. 80-140 yrs
since last disturbance.
7
Old Forest
Old, structurally complex stands comprised mainly of shade tolerant and regenerating tree species,
although older seral remnants may still dominate the upper canopy; standing snags and rotting logs on
the ground are typical and understories are patchy. Time since last disturbance> 140 yrs for these
subzones.
Table 2b.-Modifiers used in Terrestrial Ecosystem mapping (RIC 1998) to describe variations in stand structural stages.
Code
s
Definition
Modifier
Single-storied
Closed forest stand dominated by dominant and co-dominant trees; advance regeneration generally sparse.
two-storied
Closed forest stand dominated by distinct overstay and intermediate crown classes; suppressed crown class is
lacking or <20% of all crown classes combined.
multistoried
Closed forest stand with all crown classes represented.
irregular
Forest stand with very open overstory and intermediate crown classes (totaling <30% cover), with well
developed suppressed crown class; advance regeneration variable.
s
shelterwood
Forest stand with very open understory «20% cover) with well developed suppressed crown class and/or
advanced regeneration in the understory. Intermediate crown class generally absent.
v
veterans
Scattered old trees which have remained intact after a natural disturbance such as fire, but account for less then
10% cover.
residuals
Scattered trees of any size remaining intact after forest harvesting, but account for less than 10% cover.
m
Site Description and
Identification
Identification of biogeoc1imatic subzone, site series, and
structural stage requires a field description of site, soil and
vegetation characteristics of an ecosystem. Plots are 400 m 2
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and are selected to represent uniform forest ecosystems, i.e.,
areas uniform in vegetation composition and structure, and
in soil and site properties. Information recorded on site, soil
and vegetation within the plot is listed in Table 3. Soil
classification follows esse (1998). Information is recorded
on an Ecosystem Field Form, and procedures and protocols
to describe and record ecosystem properties is summarized
USDA Forest Service Proceedings RMRS-P-12. 1999
Table 3.-List of site, soil, and vegetation information collected for completing an ecosystem field plot. * indicates data collected for
Ground Inspection Plots used for Terrestrial Ecosystem Mapping.
Site
biogeoclimatic Unit *
site series *
moisture regime *
nutrient regime *
successional stage
structural stage *
site disturbance
elevation *
slope *
aspect *
mesoslope position *
surtacetopography
exposure type
surtace substrate %
UTM coordinates
Forest Region
Air Photo No.
Mapsheet No.
Notes
Soil
terrain texture *
surticial material *
terrain surtace expression *
Geomorphologic processes *
soil classification *
humus form classification *
rooting depth
water source
seepage water depth*
drainage class
flooding regime
humus form strata (hfs) depths
hfs fabrics
hfs structures
hfs root size and abundance
hfs consistence
hfs structure
von Post decomposition
mineral soil (ms) horizon/layer
ms depths
ms textures
ms coarse fragment %s
ms roots
comments on mottling, clay films,
effervescence, horizon porosity
soil profile diagram
notes as required
in BCMOELPIBCMOF (1998). Data from field forms are
entered into VENUS (1998) software for tabulation, synthesis, and analysis as required.
Assessments of site quality, i.e., of soil moisture and
nutrient regime, is based on two separate lines of evidence
- site and soil properties, and plant indicator analysis.
Combinations of site and soil factors are combined in keys to
interpret soil moisture and- nutrient regime. For example,
soil texture, depth and coarse fragment content, as well as
mesoslope position and the presence of a water table or
mottling are the most important indicators of soil moisture
regime. Humus form classification (Green et al1993), soil
texture, colour and coarse fragment lithology are the main
indicators of soil nutrient regime. Soil moisture and nutrient
regime can also be assessed from indicator plant analysis
CKrajina and Klinka 1985) when sites are not overly disturbed. Even in early successional communities, many plants
that remain from the previous disturbance, and those that
colonize the sites following disturbance will have indicator
value for climate, soil moisture, or soil nutrients. To make a
final determination of site quality the two lines of evidence
are compared and site series determined. Codes are also
available for describing whether the site represents the
central concept of the site series or whether it is transitional
to an adjacent site series.
Terrestrial Ecosystem Mapping _ _
Recently in British Columbia there has been an increased
emphasis on ecosystem mapping, primarily to meet the
requirements of the recently enacted Forest Practices Code
USDA Forest Service Proceedings RMRS-P-12. 1999
Vegetation
% cover of all trees, shrubs, herbs, and mosses growing on humus;
trees are estimated in 3 strata and shrubs in 2 strata; epiphytes and
plants growing on other substrates may also be identified
Act. Standards and protocols for Terrestrial Ecosystem
Mapping (TEM) have recently been developed and refined,
and are summarized in RIC (1998).
TEM involves the interpretation and integration of
landform, physiographic and vegetation features from
stereoscopic aerial photographs to delineate biogeoclimatic
subzone/variant and site series boundaries. In the first
step, landforms and surficial materials are defined using
the approach of bioterrain mapping (Howes and Kenk
1997). Terrestrial ecosystems within these units are then
outlined based on site series (soil moisture and soil nutrient
regimes), and stand structural stage. Ecosystem polygons
are seldom uniform in these features because of the scale of
variation in ecosystems across the landscape, in relation to
the scale of mapping. For this reason many ecosystem
polygons are 'complex' in that up to 3 different site seriesstand structural stage combinations may be recognized in a
polygon. The percentage cover of each of these components
is estimated and recorded in the ecosystem attribute data
base for all polygons. The ecosystem attribute data base
provides the basis for an ecological inventory that can be
displayed in whatever GIS formats are required. Digital
protocols and a data dictionary for terrain and ecosystem
data bases are described in RIC (1998).
Within the last few years, millions of hectares of operational forest tenures in British Columbia have had TEM
completed, mostly at a scale of 1:20,000 or 1:50,000. Most
TEM for operational applications has been carried out at
scale of 1;20,000 using 1: 15,000 air photographs. Polygon
density varies between 1,200 and 1,800 polygons per 1:20,000
map sheet. Minimum polygon area on 1:20,000 map sheets
is 1 ha and mean polygon size is between 8 and 12 ha.
323
The TEM approach integrates physical and biotic ecosystem components into a landscape summary that provides a
comprehensive inventory of ecosystem resources within
the area mapped. Underlying the ecosystem map is a map
of bioterrain that describes physiographic processes and
surficial materials, and which can be used to develop interpretations for terrain and soil management. The ecosystem
map can be used to develop interpretative maps for forest,
wildlife, and biodiversity management. Bioterrain linework is coincident with ecosystem linework in the TEM
product so that information from the two layers of information can be interpreted together. This integration provides a
comprehensive tool for ecosystem based land management
because it provides a direct link between the physical processes that determine many ecosystem properties, and the
biotic components of the ecosystems mapped.
Interpretations from BEC Units
and TEM _ _ _ _ _ _ _ _ __
It was stated above that BEC is a natural ecosystem
classification system from which interpretations can be
derived, as required by the land manager. TEM provides a
method for developing useful ecosystem maps that integrate
the physiographic and biologic components ofthe landscape.
Taken together a wide range of ecosystem-based interpretations are possible.
BEC was originally applied to the objectives of industrial
forest management and the first interpretations were developed to assist the forest manager. The six regional BEC
guides contain, for the different site series, site index estimates for the major tree species, predictions of the composition and intensity of the post-harvesting brush complex,
growth limiting factors, and regeneration considerations
such as tree species selection, slash burning guidelines, and
site preparation recommendations. More recently stocking
requirements have been adjusted to account for ecosystem
factors. Klinka et al. (199?) provided a comprehensive evaluation of silvicultural systems applicable to the different site
series.
Wildlife habitat capability and suitability rankings are
probably the most common set of interpretations presently
developed from TEM products. Algorithms for habitat suitability are based on a knowledge of present ecosystem
characteristics, while habitat capability models are based on
knowledge of how these habitat values will change with
ecosystem succession. Forage potential estimates can also
be reliably connected to site series and stand structural
stage combinations.
In British Columbia the Conservation Data Centre has
identified over 200 ecosystems it considers to be rare or
endangered, and have used the site series concept to describe these special ecosystems. Following a coarse filter
approach to bi9diversity conservation, it is now being proposed that these ecosystems be protected from harvesting or
other development. BEC and TEM are well suited to identifying and mapping these sites (Oikos 1998a,b), and for
developing reliable strategies that do not threaten the ecological processes that maintain them (Oikos 1998a,c). TEM
products provide an inventory of rare ecosystems in the
area mapped. BEC concepts of ecological process are also
324
important for developing effective management approaches
for rare plant and animal species (Oikos 1998d).
BEC is also usefully applied to management and restoration of riparian ecosystems. Site series classifications of
riparian ecosystems provide a framework for understanding
ecosystem processes such as flooding duration and frequency, natural successional processes) the impacts of the
disturbance, and feasible restoration approaches (McLennan
and Johnson 1997).
BECtrEM products provide an ecologically relevant template for developing landscape level models and for integrating additional landscape information. This is well demonstrated by GVRD Watershed Group (1998), where a forest
succession model was developed that predicted forest changes
over the next 200 years. The forest succession submodel was
included as a component of a watershed level model and was
integrated with hydrologic (sediment delivery), terrain stability, fire hazard, and forest pest hazard submodels. The
watershed model is being used by watershed managers to
compare the impacts to water quality and biodiversity from
three potential watershed management approaches, from a
large fire, and form a large forest insect outbreak. The
effectiveness of the BEC system in this application is its
direct link between biological and physiographic landscape
components, and its ability to predict plant community
composition in a forest succession model that uses
biogeoclimatic sites series as a base polygon unit.
Although BEC and TEM were developed using forested
ecosystems in British Columbia, the approach is applicable
to other temperate forest, grassland, and alpine/arctic ecosystems. Oikos (1996) demonstrated the transferability of
BEC and TEM concepts to assess potential impacts of a
mining project in the central arctic. Site series specific to the
project area were described, mapped, and interpreted for a
range of applications including rare plant communities,
grizzly bear forage potential, spring and fall caribou foraging, air quality impact indicator values, and summer and
winter trafficability rankings.
In that the BEC system is a natural classification, many
other interpretations are also possible. Examples include
rangeland and wetland management, suburbanlruralland
development, recreation planning, stakeholder analysis, and
environmental impact analysis. In all cases BEC provides
an ecosystem basis for sustainable land management
and development.
Summary and Conclusions
The Biogeoclimatic Ecosystem Classification System, together with Terrestrial Ecosystem Mapping, provides a
powerful tool for ecosystem-based land and landscape management. This effectiveness is based in a number of important aspects of the system.
1. BEC is wholistic in that it uses floristic analysis and
plant indicator species analysis to interpret the complex of
environmental factors that determine ecosystem characteristics. This analysis and integration of environmental factors reduces ecosystem complexity by relating ecosystem
properties to three major variables-regional climate, soil
moisture, and soil nutrients.
USDA Forest Service Proceedings RMRS-P-12. 1999
2. The concept of ecological equivalence means that site
series are identified that have the same vegetation potential
and ecosystem productivity. This provides a very useful
template for predicting forest successional development and
growth and yield estimates.
3. A range of ecological information is collected in the
course of sample plot analysis and this data provides a
comprehensive ecological inventory for developing interpretative algorithms. Additional information not listed in Table
3 can also be collected in sample plots as required.
4. As a component of site diagnosis, the ecosystem processes that determine ecosystem productivity and other
characteristics are assessed and recorded. Ecosystem-based
land management requires an understanding of these ecosystem processes in order to develop effective and sustainable policies.
As a result of these fundamental components of the system, BEC has the potential to provide solutions to a range of
land management issues, including certification of industrial forest operations, biodiversity conservation, riparian
area management and restoration, management of ecosystems and their processes in parks, wilderness and other
conservation areas, and management of municipal water
supply areas. The success ofBEC in all of these applications
is a result of the integration of ecosystem components that is
inherent in the classification units themselves. This kind of
wholistic, natural system is mandatory for developing ecosystem-based, sustainable land management policies.
References ____________________
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