Lecture 7 (pt2) - Bryophytes

Question 1

when were bryophytes first found

Answer 1

• First fossils found in Devonian (origin in Silurian or Ordovician)
  
  • Oldest fossil is a liverwort (Pallavicinites) -> from upper Devonian (370 MYA)
  • Fossilized spores in tetrads evidence for plant life on lands preserved in 440-470 million year old
  • Oldest moss is Carboniferous (300 MYA) -> Muscites
  • Best fossil mosses are Protosphagnales from Permian (280 MYA) in Russia

Question 2

where are bryophytes found

Answer 2

• From pole to pole -> Arctic to Antarctica and in between
  ○ Abundant in moist tropics
  ○ Few in deserts
• Epiliths (=saxicolous) = on leaves
• Epiphytes (=corticolous on bark, epiphyllous on leaves) = on tree bark
• On soil (= terrestrial)
• Aquatic but not marine
• Like lichens -> independent of substrate for nutrients, some have substrate specificity (pH/chemistry/microclimate - grow depending on environment)
• Moist environments, bathed in surface water because of aquatic fertilization -> for sperm to swim in free water to get to egg

Question 3

behaviour of bryophytes in wet and dry

Answer 3

• Like lichens -> wet quickly but dry out
  ○ Some can survive desiccation for months/years
  § Survive extreme temp when dry
  § Damaging at extreme temps when wet though

Question 4

frozen solid moss

Answer 4

○ If have liquid moisture they are active and become photosynthetic and can reproduce rapidly
○ Hydrate -> have sex -> meiosis -> spores while there are good conditions are gets frozen off and has to finish next year
When dry or frozen they are suspended - can survive in difficult environment

Question 5

bryophyte ecology and nutrition

Answer 5

• Take in nutrients through “leafy” tissues of thallus and through rhizoids and few via symbiosis with Glomerocycota
  ○ So, they are sensitive to the environment they live in
  § Acidic/basic/Ca sites
• Pollution tolerant/intolerant

Question 6

economic importance of bryophytes

Answer 6

1. Liverworts and hornworts
   a. Not much
   b. Many contain N-fixing cyanobacteria, important in ecosystem nutrient availability
2. Sphagnidae
   a. Hydrodynamics in northern hemisphere - bogs and “muskeg”
   b. Sphagnum dressings, in medicine, shoes and diapers

Question 7

bog formation

Answer 7

A. Open pond, slow moving stream
a. Margins with floating aquatics
b. Roots anchored in
B. Sphagnum builds above (growth) and below (death and deposition) water-liine; enables margin to grow inwards
C. Increased Sphagnum growth allows colonization of mat by bog shrubs, conifers (black spruce, tamarack)
D. Continued encroachment of water surface by floating bog mat may eventually cover surface if disturbance is slight - waves or stream-flow erode edges
E. Amelioration of water table by increased Sphagnum mat away from water-line allows development of forest; hummocks may have white pine or white birch
F. In permafrost areas, forest lowers summer temperature of forest floor, permafrost moves upwards, water is trapped, trees drowned, open Sphagnum bog cycles with forest

Question 8

sphagnum io-exchange mechanism

Answer 8

• Metal2+ + 2HA -> MA+ + A- +2H+
• Gives off H+, lowering pH and eliminating competing mosses and vascular plants
• Metal ions can be displaced by shaking in H+ to assay metal content

Question 9

bog side benefits

Answer 9

A. Formation of bog fossils
B. PEAT for heating fuel and horticulture - non renewing resource
C. Conservation aspects: exploitations and emissions
D. Carbon sink - unless climate warms - fungi decomposing stuff so C in the atmosphere

Question 10

Sphagnum dressings

Answer 10

in medicine, shoes and diapers
- Absorbs 16-20 X dry weight in water , comfortable, mildly antiseptic
Use in wars as dressings

Question 11

other moss uses

Answer 11

1. Housing
   a. Anti fire
   
   2. Boat-building
   3. Fibre for baskets
   4. Bedding and pillows
   5. Cultivation
   6. Mosses as living mulch in nurseries and orchards
      a. Moss gardens
      
      7. Problem mosses in lawns and roofs