Transcript Forest and Range Ecology

Outline
•Discuss definitions and components of range and
forest ecosystems
•Introduction to biological organization
•How and why do we classify organisms?
•What is a species? Why do we need to identify them?
•Interaction with environment: variability within species
•Examples
Definitions of range:
•‘Those areas of the world, which by reason of
physical limitations, low and erratic precipitation,
rough topography, poor drainage, or cold
temperatures, are unsuitable for cultivation and which
are a source of forage for free-ranging native and
domestic animals, as well as a source of wood
products, water and forest wildlife'. (Stoddart et al.
1975).
Society for Range Management:
•Vegetation is predominantly grasses, graminoids,
forbs or shrubs; managed as a natural ecosystem.
•If plants are introduced they are managed similarly.
•Rangelands include natural grasslands, savannas,
shrublands, many deserts, tundras, alpine
communities, marshes, and meadows.
Forest:
• Area of 0.5-1 Ha, 10-30% tree canopy cover,
trees >2-5 m at maturity
• 10% stocked by trees, and not subject to uses
preventing normal tree regeneration (eg. Heavy
grazing, mowing)
• “Area managed for production of timber and other
forest products, or maintained as wooded
vegetation for such indirect benefits as protection
of catchment areas or recreation”. (Lund 1998)
Range management:
Rangeland management is ‘the science and art of
optimizing the returns from rangelands in
combinations that are most desired by and
suitable to society through the manipulation of the
range ecosystem’
(Stoddart et al. 1975)
Range management:
Applies knowledge from range science and practical
experience.
• Protection and improvement of resources (ie
sustainability).
• Optimum production of goods and services.
• “The overriding goal is rangeland resource
rehabilitation, protection, and management for
multiple objectives including biological diversity,
preservation, and sustainable development for
people." (Heady and Child 1994)
Components of Ecosystems
• Abiotic:
• Biotic:
Processes of Ecosystems
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Carbon fixation (productivity)
Nutrient cycling
Water cycling
Energy transfer between trophic levels
Materials transport (erosion, deposition)
Decomposition (cycling)
Forests
• What processes, components, services
are important in forests?
Rangeland
• What processes, components, services
are important in rangelands?
Classifying Biotic components
• How do we classify organisms?
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Trophic levels (ecosystem roles)
Life form (e.g. plant growth forms)
Life history (e.g. length of life)
Phylogeny (evolutionary relationships)
Taxonomy
Classifying Biotic components
• Why do we classify organisms?
– To understand ecosystem functioning
– To understand relationship of organisms to
environment and each other, and predict
responses.
Species
• What is a species?
– Many definitions (25 +)
– Some definitions based on characteristics of
organsims, some based on reproduction,
some based on phylogenetic descent.
– 3 main ideas:
• Morphological
• Biological (BSC)
• Evolutionary/phylogenetic
Species Concepts
• Morphological: group of animals or plants
sharing one or more distinct characters.
• Biological: Similar natural populations that are
reproductively isolated from other populations.
• Phylogenetic: a cluster of individuals with a
common evolutionary ancestry. “Units of
evolution”.
Species Concepts
• Species definition combines morphology,
breeding, and habitat.
• Taxonomic species: combines mainly
morphology and BSC. Somewhat
arbitrary and distinctions are not clear.
• Composed of “ecologically important
subunits”? Or is variation continuous?
(ecotypes or ecoclines)
Species Concepts
“A species is a group of individuals, which,
in the sum total of their attributes,
resemble each other to a degree usually
accepted as specific, the exact degree
being ultimately determined by the more
or less arbitrary judgement of
taxonomists”
Why are species important?
Why are species important?
• We consider that “species” respond as units to
environmental conditions (=ecotypes?).
• Considered to be “units of evolution” – stage
where biological discontinuity takes place.
• “Specieshood” related to genetic and ecological
differences (even if not perfectly). Species
richness =simple measure of biological diversity.
• Endangered species: populations with distinct
characteristics (ecological, reproductive, and
morphological). In danger of extinction, are
different enough from similar groups to warrant
salvage.
Species in range and forest
ecology
Species in range and forest
ecology
• May use species-based measures to
assess health, identify potential land uses,
predict habitat quality,etc.
• Species composition related to community
characteristics.
• Economically important species (e.g.
timber trees, good forage species)
Species in range and forest
ecology: summary
• “Species” difficult to precisely define.
• All definitions are somewhat arbitrary.
• Variation in response to environment within given
species.
• We need and want to classify organisms, so
“species” still used.
• Even though imperfect, taxonomic species ID can
and is for assessing ecosystem characteristics,
understanding community dynamics, and making
management decisions.
Species in range and forest
ecology: summary
Variation in species (ch. 3)
• Substantial variation within taxonomic species:
heritable, adaptive characters (Turesson)
• e.g. hawkweed in Sweden (ecotypes):
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Three habitats (woodland, field, dune)
Differ in traits: habit, leave shape, dormancy
Traits maintained when grown in greenhouse
All groups interfertile
• Similar experiment in California (Clausen et al
1940).
Variation in species
• “common gardens” at Stanford, Mather (Midelevation Sierra Nevada), and Timberline (3000m
elevation)
• Grew 60 different species collected from a range
of sites from coast to eastern slopes
• Potentilla glandulosa ecotypes (subspecies) differ
in growth form, frost and disease and survival in
different gardens (see textbook Ch. 3)
Variation in species
• Additional examples: readings
– Saltgrass frost tolerance: Crop Science 43:2142-2147
– Norway Spruce altitudinal ecotypes: Functional
Ecology 12:573-590
Subspecies or different
species?
• Pinus contorta – three subspecies. Contorta not fire
adapted (shore pine). Latifolia (rocky mountain lodgepole)
fire dependent; dominance in landscape and proportion
serotinous cones related to fire frequency. Murrayana
(sierra lodgepole) fire sensitive, but early after-fire
coloniser. Not serotinous.
• Pinus ponderosa and Pinus jeffreyi. Differ in resin
chemistry and habitat (elevation). Are sympatric at midelevation, and hybridize.
• Ord’s kangaroo rat in Alberta – hibernate. Don’t hibernate
anywhere else. Is this peripheral population worth saving
as a distinct taxon?