Transcript Lecture 1 Thursday Jan. 4, 2001

BIOLOGY 3404F
EVOLUTION OF PLANTS
Fall 2008
Lecture 10
Thursday October 23
Chapter 16, The Bryophytes
Part II
WHERE?
• From Arctic to Antarctic and everywhere in between,
abundant in moist tropics, and a few occur in deserts.
• Like lichens, they wet rapidly but dry out much more
rapidly.
• Some can survive desiccated for months or years and
can survive extreme temperatures when dry, but rapid
drying or extreme temperatures when wet can be
damaging.
WHERE II
• Epiliths (= saxicolous), epiphytes (= corticolous if on
bark, epiphyllous on leaves), on soil (= terrestrial), or
aquatic, but not marine
• Like lichens, are largely independent of substrate for
nutrients, but may have some substrate specificity
because of pH or other chemistry, or microclimate.
• Tend to be found in moist environments, bathed in
surface water, because of aquatic fertilization
Bryophyte ecology and nutrition
• Bryophytes, like lichens, may take in nutrients
through “leafy” tissues of thallus, in addition to
uptake through rhizoids and (in a few) via symbiosis
with Glomeromycota
• Because of this, they are sensitive to the
environments where they live: some prefer acidic
sites, others basic or calcium-rich sites; some are
pollution intolerant, others tolerant
• Saxicolous, corticolous, epiphyllous, …
Economic Importance of Bryophytes
I. Liverworts and hornworts: not much! (but many contain Nfixing cyanobacteria, important in ecosystem nutrient
availability; some are mycorrhizal with Glomeromycota)
II. SPHAGNIDAE: "economic" importance
• 1. Important in hydrodynamics of large areas of especially
northern hemisphere - bogs and “muskeg”.
• 2. Sphagnum dressings, in medicine, shoes and diapers
• III. Other mosses, various other uses
BOG FORMATION
• a) open pond, slow-moving stream: margins with
floating aquatics, especially Carex spp. with roots
anchored in Sphagnum
• b) Sphagnum builds above (growth) and below
(death and deposition) water-line; enables margin to
grow inwards
• c) increased Sphagnum growth allows colonization
of mat by bog shrubs, and eventually conifers such as
black spruce & tamarack
Bog Formation II
• 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 upward, water is trapped, and
trees are drowned, so open Sphagnum bog cycles with forest
SPHAGNUM ION-EXCHANGE
MECHANISM
• Metal2+ + 2HA ---> MA+ + A- + 2H+
• Gives off H+, lowering pH and eliminating
competing mosses (and many vascular
plants)
• Metal ions can be displaced by shaking in
H+ (e.g., dilute HCl) to assay metal content
BOG SIDE-BENEFITS
a)
b)
Bog fossils
PEAT (1.5m = 6,000y): for fuel and
horticulture
c) Conservation aspects: exploitations and
emissions
d) Carbon sink – unless climate warms!
Sphagnum dressings, in medicine, shoes
and diapers
• Absorbs 16-20 X dry weight in water (cotton 4-6); comfortable;
mildly antiseptic (vs diaper rash, gangrene)
• Sphagnum dressing used greatly in wars: Russo-Japanese (19045); WW I (both sides). Millions of dressings made by thousands of
volunteers
a) crude sphagnum collected, partially air-dried, cleaned of debris, and
sorted.
b) wrapped in sewn gauze
c) sterilized before use by autoclaving or with antiseptics
d) preferred species was S. papillosum; also used were S. palustre, S.
imbricatum & S. magellanicum
From Prince Rupert Public Library
III. Other Mosses, Other Uses:
1. Housing
2. Boat-building
3. Fibre for baskets
4. Bedding and pillows
5. Cultivation
6. Mosses as living mulch in nurseries and
orchards
7. Problem mosses in lawns and roofs