Lecture 12: Arctic Ecosystem Flashcards
(36 cards)
arctic general characteristics
- coldest biome above 66 N
- youngest biome
- slight overlap w boreal forest
- 20-25% earth surface
- variable ecosystems (top to bottom)
arctic characteristics: plants
- 1700 spp. of plant
- 400 spp of flowering plant
- huge diversity of mosses and lichens
challenges for plants in arctic:
- low temps and substantial variation (- to 20DC at bottom)
- low soil fertility
- drought conditions “polar deserts” (real and frost drought)
- short and late growing seasons (as u move further north, grow season gets shorter)
benefits to arctic life
- snow insulation (protection from winter cold)
- 24 hour daylight in summer (midnight sun)
are there seasons in the arctic??
yes, summer snow w some greens
winter = majority = snow
amount of ice covergae in arctic is important for
earths albedo
- increasing temps = less snow, less light reflected, more hitting earth, increased temps for earth
key adaptions for organisms in the arctic
few “unique” adaptions
- many based on avoidance rather then trus adaptions
adaptions specifically to plants: low stature and dense growth forms
- traps air and insulates the plant
- leaves at 90DC to sun can be 15 DC warmer
- protection from wind/ice blast
- covered by snow in the winter
- e.g. Silene acaulis
Arctic plant adaptions for growth:
• Low / dense growth forms • Rapid response to spring • Physiological activity at low temperatures • Freeze tolerance
adaptions specifically to plants: prostrate plants
also known as amt-forming plants
- especially in high arctic
adaptions specifically to plants: prostate plants & low stature and dense growth forms + organic matter
maintains organic matter better
adaptions specifically to plants: dwarfism
Salix polaris is a willow tree but v close and low to floor
low growth habitats also found in other biomes =
polar and desert (Arizona)
start of growing period in arctic =
spring, have to act fast at the beginning
low dense growth form examples
- prostrate plants
- low stature and dense growth forms
plants response to spring:
rapid bud burst soon after or even during snow melt o maximise growing season
- issue: false signal?
adaptions specifically to plants: maintain physiological activity at low temperatures
- plants are adapted to photosynthesise at low temperature
- allows growth in early spring
- max growth even in a cool summer
maintaining physiological activity examples
lichens (rlly good example)
- lichen abundance and diversity INCREASES at higher latitudes (in contrast to vascular plants)
- can photosynthesise at -5 DC
adaptions specifically to plants: low nutrient availability means that tissue production is
tissue production is costly
- mainly long lived perennial plants
- reabsorb nutrients from dying leaves and root (litter produced = poor in nutrients)
- slow growing
- low nutrient conc in leaves
- lots of investment in roots
adaptions specifically to plants: lots of investment in roots
- root:shoot biomass ratio is on average 6:1
- not deep, just lots of shallow roots
- roots live longer than leaves
- BECAUSE of low nutrient availability
LOW nutrients availability: N fixing legumes, parasitic plants, insectivorous plants
common to gain nutrients
arctic plants and stress avoidance
LOW nutirents = LOW stress tolerance
- N deficiency inhibits the protein synthesis necessary to recover from photochemical damage
- bryophyte = top section is non-photosynthetic just a sunscreen to protect bottom
arctic plants and solar tracking
common
- arctic poppy
- at 83 DC north
arctic plants and desiccation resistance
- despite snow, summer precipitation is low
- ADAPTIONS:
- – cushion, prostate & dwarf growth helps reduce water loss
- slow growth demands less water
- leaf adaptations (similar to that in deserts) i.e. rolled leaves
