Скачать презентацию Boreal forest v Biophysical environments v Biotic interactions Скачать презентацию Boreal forest v Biophysical environments v Biotic interactions

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Boreal forest v Biophysical environments v Biotic interactions v Fire regimes & post-fire succession Boreal forest v Biophysical environments v Biotic interactions v Fire regimes & post-fire succession v Floodplain succession & paludification v Forest clearance and succession v Climate change: natural & anthropogenic

Boreal forest biome ------- Scandinavia 70% Russia 70% Alaska 50% Canada Fairbanks Pr. Albert Boreal forest biome ------- Scandinavia 70% Russia 70% Alaska 50% Canada Fairbanks Pr. Albert Chicoutimi Kapuskasing Note latitudinal variation

Mean monthly temperature J F M A M J J A S O N Mean monthly temperature J F M A M J J A S O N D

Monthly precipitation (mm) Monthly precipitation (mm)

Mean annual snowfall (mm) Bo re al fo re st zo n e Mean annual snowfall (mm) Bo re al fo re st zo n e

Boreal forest and permafrost distribution -2. 8° Mean annual temperature 0. 6° 0. 7° Boreal forest and permafrost distribution -2. 8° Mean annual temperature 0. 6° 0. 7° 3. 0° Discontinuous permafrost limit ~ -2°C

Jan tree growth July 120 150 Mean location Polar Front 30 pollen/seed viability Mean Jan tree growth July 120 150 Mean location Polar Front 30 pollen/seed viability Mean #d >10°C 240 Mean #d <0°C Boreal forest patchy discontinuous Tundra continuous Permafrost

Boreal forest-environment interactions Biota Climate Physical template Soil Boreal forest-environment interactions Biota Climate Physical template Soil

The boreal forest biome in Canada “T Bo aig re a a” lf or The boreal forest biome in Canada “T Bo aig re a a” lf or e st

Trees of the N. American boreal forest Evergreens Deciduous Trees of the N. American boreal forest Evergreens Deciduous

Boreal forest vegetation types (North America) Boreal forest vegetation types (North America)

Forest structure Boreal forest spruce/birch/pine forest mosaic Taiga spruce-lichen woodland Forest structure Boreal forest spruce/birch/pine forest mosaic Taiga spruce-lichen woodland

Boreal forest soils Underlain by coarse-textured deposits or bedrock. Well-drained, warm fairly rapidly in Boreal forest soils Underlain by coarse-textured deposits or bedrock. Well-drained, warm fairly rapidly in summer, more rapid breakdown of organics, strongly -leached, acidic, low nutrient availability. 100 Bf gleysols, cryosols % cover O Ae Underlain by fine-textured deposits / permafrost. Poorlydrained, cold in summer; little microbial activity, slow breakdown of organics, low nutrient availability. Podzols, Cg regosols 0 south boreal forest north taiga O BC

Forest community segregation in the boreal forest black spruce tamarack white spruce birch-aspenbalsam fir Forest community segregation in the boreal forest black spruce tamarack white spruce birch-aspenbalsam fir jack pine mosses site: wet soil: gleys active: thin (<0. 3 m) layer organic thick layer mesic dry podzols thick (>2 m) (or no permafrost) thin

Biomass and productivity black spruce white spruce paper birch aspen poplar Biomass and productivity black spruce white spruce paper birch aspen poplar

Nutrient cycling and storage (nitrogen) black spruce white spruce paper birch aspen poplar Nutrient cycling and storage (nitrogen) black spruce white spruce paper birch aspen poplar

Herbivory and boreal forest dynamics Moose population Nitrogen mineralization Browse biomass Wolf population enhancements Herbivory and boreal forest dynamics Moose population Nitrogen mineralization Browse biomass Wolf population enhancements phytotoxins soil microbiota reductions

Insect outbreaks (e. g. spruce budworm; Siberian silkworm) Climate (early summer drought) Insect populations Insect outbreaks (e. g. spruce budworm; Siberian silkworm) Climate (early summer drought) Insect populations (larvae) Fire hazard Forest structure* and biomass *suitable host trees (e. g. balsam fir for spruce budworm) enhancements reductions

Fire regime Fire cycle • Natural fire cycle averages 50 -200 years • Length Fire regime Fire cycle • Natural fire cycle averages 50 -200 years • Length of the cycle controlled by moisture balance • Most fires small (~70% in AK & YK <5 ha). • Severe fires can cover 200, 000 ha. • Most boreal forests equally flammable regardless of age (after first decade).

Forest fire weather zones Forest fire weather zones

Precipitation and wildfire frequency Precip. Fire RI Precipitation and wildfire frequency Precip. Fire RI

Fire regime Fire intensity • Most tree species are not fire resistant. Thick bark Fire regime Fire intensity • Most tree species are not fire resistant. Thick bark protects pines. • Tendency of fire to crown dependent on tree canopy architecture and understorey vegetation. Crown fires common in spruce and pine forests, rare in deciduous forests.

Fire resistance: protective role of tree bark paper birch black spruce resistance jack pine Fire resistance: protective role of tree bark paper birch black spruce resistance jack pine

Fire regime Post-fire regeneration • Many trees dependent on recurring fires. • Post-fire reproduction Fire regime Post-fire regeneration • Many trees dependent on recurring fires. • Post-fire reproduction by means of: light, wind-dispersed seeds (e. g. birches, poplars) serotinous or semiserotinous cones (e. g. jack pine, black spruce) stump sprouting or suckering (aspen, paper birch)

Post-fire regeneration from suckers from serotinous cones Post-fire regeneration from suckers from serotinous cones

Fire succession no Fire succession no

Birch (Betula papyrifera) forest with spruce (Picea sp. ) understorey on mesic site Birch (Betula papyrifera) forest with spruce (Picea sp. ) understorey on mesic site

Fire regime Fire severity • Removal of the canopy and surface organic layer increases Fire regime Fire severity • Removal of the canopy and surface organic layer increases surface energy receipt. Thickness of active layer may increase substantially for first few years following fire. • Nutrients in surface mat and soil released by fire (N and P increase most in moderately burned areas).

Succession schematic Succession schematic

Floodplain succession, Alaska Floodplain succession, Alaska

Floodplain succession ( pioneer phase) Floodplain succession ( pioneer phase)

Floodplain succession ( pioneer phase) white spruce Balsam poplar herbs Floodplain succession ( pioneer phase) white spruce Balsam poplar herbs

Floodplain succession (climax phase) mature white spruce on scroll bars Floodplain succession (climax phase) mature white spruce on scroll bars

Floodplain succession, NE BC Floodplain succession, NE BC

Influence of forest cover on soil temperature Influence of forest cover on soil temperature

In the absence of disturbance paludification may occur • Moss-organic layers > 5 cm In the absence of disturbance paludification may occur • Moss-organic layers > 5 cm thick preclude spruce regeneration from seed. • Spruce stands may reproduce vegetatively by layering (regrowth of low branches buried in the moss-organic mat). • If moss-organic layer continue to increase in depth, paludification (bog-formation) may occur. In W. Siberia ~1/3 of the taiga is forested bog.

Paludification: a double feedback loop soil water table Sphagnum nutrient uptake Sphagnum moss growth Paludification: a double feedback loop soil water table Sphagnum nutrient uptake Sphagnum moss growth ironpan formation soil acidity enhancements peat development tree growth reductions

Sphagnum bog formation Sphagnum bog formation

Effects of successional paludification of boreal forest soils (in western Québec) Data: Simard et Effects of successional paludification of boreal forest soils (in western Québec) Data: Simard et al. , 2007. Ecological Applications 17, 1619 -163

Effects of paludification on forest timber production Left: stand opens up over time, and Effects of paludification on forest timber production Left: stand opens up over time, and Right: wood production declines (especially in stands >200 -yr old) Data: Simard et al. , 2007. Ecological Applications 17, 1619 -163

Forest clearance in NW Europe Forest clearance in NW Europe

Farm clearance-abandonment cycle (data from New England) Farm clearance-abandonment cycle (data from New England)

Wood production areas Wood production areas

Effects of harvesting on forest cover in accessed areas of boreal forest poplars % Effects of harvesting on forest cover in accessed areas of boreal forest poplars % change balsam fir pine spruce birch other

North American vegetation at the Last Glacial Maximum (18 000 14 C yr BP North American vegetation at the Last Glacial Maximum (18 000 14 C yr BP = 20 000 yrs BP)

Postglacial migration of the boreal forest plant community from pollen evidence Pollen Viewer http: Postglacial migration of the boreal forest plant community from pollen evidence Pollen Viewer http: //www. ncdc. noaa. gov/paleo/pollen/viewer/webviewer. html

LGM and Late Glacial distribution of boreal and mixed forest from pollen evidence Boreal LGM and Late Glacial distribution of boreal and mixed forest from pollen evidence Boreal = dark green Mixed forest = light green No analogue Overpeck et al. , 1992. Geology 20, 1071 -1074

Ranges, clades and postglacial migrations of New World tree squirrels (T = Tamiasciurus) Douglas Ranges, clades and postglacial migrations of New World tree squirrels (T = Tamiasciurus) Douglas squirrel T. douglasii ? eastern clade ? Red squirrel T. hudsonicus SW clade “T. mearnsii” Simplified from data in Abrogast et al. , 2001. J. Mammalogy 82, 302 -319

Range, fossil sites and inferred postglacial migration of American marten Martes americana varieties: americana Range, fossil sites and inferred postglacial migration of American marten Martes americana varieties: americana and caurina • fossils Stone et al. , 2002. Molecular Ecology 11, 2049– 2063

Sphyrapicus (sapsuckers) Dendroica (warblers) Vermivora (warblers) Passerella (warblers) Vireo (vireos) Empidonax (flycatchers) Opopornis (warblers) Sphyrapicus (sapsuckers) Dendroica (warblers) Vermivora (warblers) Passerella (warblers) Vireo (vireos) Empidonax (flycatchers) Opopornis (warblers) “Superspecies” complexes of boreal forest birds: note repetitive distribution patterns Poecile (chickadees) Weir and Schluter, 2004. Proc. Roy. Soc. London B, 217, 1881 -1887.

Cladogram of boreal bird superspecies Map shows ice cover at LGM and approximate distribution Cladogram of boreal bird superspecies Map shows ice cover at LGM and approximate distribution of boreal forest glacial refugia cold d 18 O Clock for DNA cladogram = 2. 2% change in DNA per Ma palaeotemperature warm Ma (BP) 2. 0 1. 5 1. 0 0. 5 0. 0 Weir and Schluter, 2004. Proc. Roy. Soc. London B, 217, 1881 -1887.

ADVANCE = north; RETREAT = south ADVANCE = north; RETREAT = south

Changes in the boreal forest margin in southern Sweden since 1250 BC Changes in the boreal forest margin in southern Sweden since 1250 BC

Global climate change and the boreal forest: growth fire frequency paludification ? Global climate change and the boreal forest: growth fire frequency paludification ?