2. Adaptations of Plants to High Elevation Flashcards
What does “alpine” mean?
“white” or ”snow-covered” (latin)
“alp”, “alb”, “alpo” (indo-germanic, basques)
What is the definition of alpine vegetation?
Any low stature vegetation above the climatic tree-line
worldwide
What is the definition of alpine plant?
Plants that are almost exclusively found in the alpine zone
What are the altitudinal vegetation zone?
Lowland, Submontane: forest and bush organized by species composition
Montane: montane forest >5 m high
Upper Montane: montane forest 2-5 m high
TREELINE
Subalpine: shrubs and trees 0.5 - 2 m high
Alpine: herbs, shrubs, <0.5 m high, rosette plants
UPPER LIMIT OF VASCULAR PLANTS
Nival and subnival: Only cryptograms
What are vascular plants?
- Plants that distribute water and minerals throughout their body
- Have true roots, leaves and stem
- Can acquire larger size than non-vascular plants
ex. Examples of life-forms: shrubs, grasses, forbs, ferns (mostly perennial)
What is the highest known occurrence of vascular plants?
6400 m, collected during 1935 and 1952 Mount Everest expeditions
(Saussurea gnaphalodes, Lepidostemon everestianus)
Plants derive energy from what?
Photosynthesis
How does photosynthesis work?
carbon dioxide + water —light–> sugar + oxygen
- Green plants use light energy to convert carbon dioxide and water into sugar and oxygen.
- Sugars produced in photosynthesis are converted into biomolecules that make up the dry weight (biomass) of a plant.
What are chloroplasts (in cells)?
sites of photosynthesis, contain chlorophyll - a pigment that is essential to photosynthesis. Located in leaves (and stems) of plants.
What specific light wavelength does photosynthesis occur at?
400-700 nm (visible light)
Ultraviolet light, specifically UV-B (280-320nm), penetrates through the stratosphere and has what kind of effect on photosynthesis?
A damaging effect: its higher energy content can destroy biological tissue and DNA.
What is high UV-B irradiation?
- UV-B intensity decreases with latitude
- UV-B intensity increases with altitude (but clouds can counteract this)
The alpine environment does not exist but some frequent features are…
- High UV radiation
- Reduced mean temperature (low-temperature extremes)
- High-temperature fluctuations
- Windy
- Short growing season
- Precipitation often as snow
- Shallow soils
- Low water and nutrient avaliability
What plants need: Liquid water
Availability at high altitudes: ?
Limiting (not readily available)
What plants need: Light
Availability at high altitudes: ?
Limiting (à long snow cover, clouds)
What plants need: Warmth
Availability at high altitudes: ?
Limiting
What plants need: Nutrients
Availability at high altitudes: ?
Limiting
What plants need: p(CO2) partial pressure of cardon dioxide
Availability at high altitudes: ?
Decreases (but higher than historically)
à Global warming, Körner (2002)
What is a limiting factor?
An environmental factor that restraints abundance, growth and
dispersal in organisms
What is an adaptation to high UV-B irradiation
- Dense hairiness
- Thick epidermis (outer leaf layer) with beneficial compounds
- Some alpine plants build anthocyanins to avoid damage by UV-B light
- : Epidermis (outer leaf layer) absorbs a lot of UV light in alpine plants. : Effect possibly due to extractable compounds in epidermis (Extract contained flavonoids, lipids, cuticular waxes)
Example of a species with dense hairness?
Leontopodium nivale
What are anthocyanins?
water soluble pigments (red, purple, blue)
Example of a species that uses anthocyanins?
Oxyria digyna, Mountain sorrel
Adaptation to cold temperature?
- Alpine plants have a flexible photosynthesis: it operates near maximum over a wide temperature range.
- Photosynthesis is mostly limited by low light (quantum flux density) in high-altitude conditions, not temperature!
Adaptation to a short growing season?
Short growing seasons means few pollinator encounters! Prolonged flowering to compensate for rare pollinator visits
Adaptation to low nutrients (and low water availability)?
Many alpine plants invest in below-ground rather than in above-ground biomass. They also have a finer root structure and form often a symbiosis with mycorrhizae (symbiotic fungi).
Adaptation to strong winds?
- Tolerance: Low stature, appressed to ground. Flexible stem
- Avoidance: Colonization of windless microsites
Adaptation to dry conditions?
Growth features that we otherwise see in deserts:
- Succulence
- Waxy leaf surface
- Hairiness
Example of a plant which adapts to short growing season?
Silene acaulis, moss campion
Example of plant with high tolerance to high winds?
Leuseleuria procumbens
Example of plant that can store water in leaf and stems
Succulent plant: Sempervivum montanum
Adaptation through growth forms?
- Cushion plants
- Herbaceous rosette-forming plants
- Graminoids (grasses, sedges) often tussock-forming
What are cushion plants?
Cushion form in alpine plants is a genetically inherited form
– not the results of harsh conditions
- Avoidance of wind andlow extreme temperatures
- Possibly also a way to trap nutrients: keep dead biomass from being blown away
- But danger of overheating
What are herbaceous rosette-forming plants?
- Avoidance of wind and extreme low temperatures
- Decoupling from atmospheric temperatures
What are graminoids (grasses, sedges)
- Flexible stems and leaves: wind tolerance
- Avoidance of low temperatures
- Microclimate regulation
- Nutrient trapping
“In Carex curvula, DNA analysis of clonal expansion suggests genet ages of several thousands of years.
- These plants may be functionally immortal.“
Example of a cushion plant
Silene acaulis, moss campion
Example of a herbaceous rosette-forming plants
Saxifraga paniculata, white mountain-saxifrage
Example of graminoids (grasses, sedges)
- Carex sempervirens, evergreen sedge
- Clonal growth of a fescue species, Andes,
