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Biological proxies. Plants as indicators of terrestrial environments. Tissue/organs: Support --> wood (tree rings) Photosynthetic --> leaf anatomy (stomata) Reproductive --> pollen, (cones) seeds Detritus --> charcoal. Dendroclimatology: basics. - PowerPoint PPT Presentation
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Biological proxies
Plants as indicators of terrestrial environments
Tissue/organs:Support --> wood (tree rings)
Photosynthetic --> leaf anatomy (stomata)
Reproductive --> pollen, (cones) seeds
Detritus --> charcoal
Dendroclimatology:basics
• Plants are responsive to variations in the ambient physical environment;
• Response is expressed by variations in growth, reproductive effort, etc.;
• Growth response is recorded in woody (nontropical) trees by variations in the thickness of annual rings;
• The environmental stimuli can be revealed by analyzing ring widths of living or fossil trees from sensitive sites.
Environment - site interactions
temperature-sensitive
annual ringsbark
drought-sensitive
complacent
Tree rings as proxies
Measuringtree ringwidths
Tree ring records, N. Eurasia (AD 0 - 2000)
Spatial patterns:
the megadrought of 1863 in
the USA
Reconstructing fire history from scars
and wounds
Fire history sites, SW USA
Constructing regional
fire histories
Tree rings and volcanismdust veil
‘frost ring’
e.g. LaMarche and Hirschboeck, 1984, Nature 307, 121-126
narrow/frost rings recorderuptions in spring/summer only?
Hemispheric analysesof tree ring density reveal
annual and spatial variations in climate
[Northern hemisphere; AD 1815-1817]
“The year without a summer”
Eruption ofTambora continues
Palynology: pollen proxies
• Plants produce morphologically distinctive pollen grains.
• Pollen “rain” is representative of the local plant community (apart from non-anemophilous spp.).
• Pollen grains are extremely resistant to decay in anoxic conditions (e.g. lake sediments, peat bogs, wetland soils).
• Pre-existing plant communities can be reconstructed by sampling fossil assemblages in these sedimentaryarchives.
• Palaeoclimates can be derived from the ecological ranges of the constituent species.
Pollen morphology I
Pollen morphology II
Pollen typesPinus
Tsuga
Poaceae
Achillea
Tsuga occidentalis range limits % isopolls
Species range, pollen rain and environment
-20 -10 0 10 20 30
Temperature (°C)
Ann.Jan.
July
Precipitation (mm)
Ann.Jan.
July
1 10 100 1000 10000
Relative pollen %
and summer
temperature (Yukon)
Pollen capture by lakes
EXTRA-LOCAL(20 TO SEVERAL
HUNDREDMETRES
FROM LAKE)
LOCAL(<20 METRES FROM LAKE)
0 100 200 300 1000
REGIONAL(UP TO SEVERAL HUNDREDKILOMETRES FROM LAKE)
LAKE DIAMETER (M)
% T
OTA
L P
OLLEN
100
0
Pollen representation (‘R-value’: Inuvik area)
“Over” “Equal” “Under”
alder 11.8 juniper 1.0 spruce 0.5sage 5.0 willow 0.6 larch 0.2grass 3.4 poplar 0.6 heaths 0.1birch 3.0sedge 2.2 R = 1;
pollen production =species abundance in vegetation
Pine pollen percentage vs. influx (Rogers Lake, Connecticut)
0
2000
4000
6000
8000
10000
12000
14000
Rad
iocarb
on
yrs
BP
% of total Influx (‘000 grains/cm2/yr)
0 20 40 60 0 10 20
L
ate
H
olo
cen
e G
lacia
l
Pine needles(regionalpattern)
Plant macrofossilsas proxies
Stomatal patterns
Monocots (linear) Dicots (random)
Stomatal density and [CO2]
Reconstructed atmospheric CO2
levels from 300 Ma to PD
Charcoal influx
(mm2 cm-2 yr-1), Lake
Francis, Abitibi, Québec
http://www.consecol.or
g/vol2/iss2/art6
Local fires
Regional fires(background)
Insect proxies (e.g. Coleoptera [beetles])
1. Fossil extraction (washing [solvents include kerosene] & sieving). 2. Taxon ID: morphology, microsculpture & genitalia (X100)
head capsule
pronotum
elytra(singular=
elytron)
Beetles in UK
“Devensian”
deposits (=OIS 2/3)
A-C = thermophil
es
D-G = tundra /alpines
H = cosmopolit
anspecies
(after Coope)
barren = full glacial
Modern ranges of cold-tolerant beetles from UK Devensian deposits
Modern ranges of thermophile beetles from UK Devensian deposits
Devensian exotica(periglacial deposits)
“interglacial refuge”
Terr
est
rial sh
elly
invert
ebra
tes
Terrestrial vertebrates
Alan Griffiths; discoverer of
fossil bear bones, QCI, from ~15 ka BP
(map of LateGlacial
vertebrate fossil finds)
Photos: Vancouver Sun
Packrat middens
Neotoma cinerea
fossil extractionsampling a midden
midden site (Colorado)
Packrat middens:sample
sites
(BC)
Pinus edulis:distribution records in US SW from packrat middens