Global Biogeography グローバル生物地理学

Global Biogeography　グローバル生物地理学
Fur seals on a rock, Western Cape Province, Republic of South Africa.
Exploitation of the Low-Latitude Rainforest Ecosystem
EYE ON GLOBAL CHANGE
The rainforest ecosystem, home of
the world's most diverse collection of
plants and animals, is threatened by
deforestation and conversion to
cropland and rangeland.
熱帯雨林
どこにあるか
・南アメリカ
・東南アジア
・アフリカ
生物多様性
・genetic reservoir of many species
熱帯雨林の利用
・slash-and burn method 焼き畑
・現代の利用は？
なぜ、熱帯林
1：熱帯多雨林、2：熱帯・亜熱帯の半常緑樹林、2a：熱帯・亜熱帯のサバンナ・低木林など、3：
熱帯・亜熱帯の砂漠・半砂漠、4：冬雨地帯の半緑硬葉樹林、5：暖温帯常緑広葉樹林、6：冷温
帯夏緑広葉樹林、7：温帯草原（ステップ、プレーリー、パンパ）、7a：寒冷な冬をもつ砂漠・半砂
漠（チベットを含む）、8：北半球の北方針葉樹林（タイガ）、9：ツンドラ、10：アルプスなどの高山
植生　（林一六、「植生地理学」、原図はWalter,1968）
焼き畑農業　slash-and-burn agriculture
熱帯林の破壊－どうすれば止められるか
1990
2000
土地被覆変化と
私たちの暮らし
Natural Vegetation　自然植生
Natural vegetation is a plant cover that develops with little or no human
interference.
⇔　human-influenced vegetation
Most of the Earth's land surface is influenced subtly or strongly
by human activities, including clearing for agriculture and grazing,
fire suppression, and introduction of alien plants and animals.
The great Yellowstone fire
After the burn(left) and Ten years later(right)
潜在植生、自然植生、原生林、二次林
［植生図］　地表の植生の分布を地図上に描き分けた図
日本全体の植生図は多くの場合、4つの植生帯として描かれる。
①常緑広葉樹林帯（シイ・カシ林）
②冷温帯夏緑広葉樹林（ブナ・ミズナラ林）
③北方針葉樹林（エゾマツ林、シラビソ林）
④暖温帯夏緑広葉樹林（ナラ・シデ林）
⇒［原植生図］　日本列島に人間の作用がほとんど加わっていなかった時
代の植生を現代の知識で復元
⇒［推定極相図］現在のある地域に人間の作用を全く加えず、充分長い時
間(200年くらい）自然条件に放置しておいた場合に成立するであろう植生
［現存植生図］　図を描く時点で現実に分布している植生や耕地、市街地
などを忠実に地図の上に描いたもの
［潜在自然植生図］　潜在自然植生（Tuxen,1956)とは、「現在の気候およ
び土壌条件下において人間の干渉なしに遷移が完成した時に成立する
植生構造」。この推定された植生を地図上に描いた図。
潜在自然植生図≒推定極相図
(林一六著、「植生地理学」、大明堂）
［自然林］　人間が植栽した林以外のすべての林を指し、伐採した林
や火入れをした林でも、そこから自然に回復した林はすべて自然林
［一次林（原生林）］　自然林のうち、過去一度も人為の加わらない森
林。極相に達した一次林と遷移の途中相のものがある。
［二次林］　過去に幾度か人為の加わった林を指す。
日本列島の潜在植生（右）と二次林
の分布（杉谷ほか著、「風景のなかの
自然地理」、古今書院）
Human activities Deforestation and desertification
Deforestation
- Frontier forest
- Degraded forest (large, mostly virgin forest)
- Frontier forest 8,000 years ago
Clear cutting
Wood gathering
Desertification
- Very high
- High
- Moderate
- Low
Slash-and-burn
気候学的に必然的に
存在する砂漠
＜峻別＞
人により荒廃した
半乾燥地域
Overgrazing
STRUCTURE AND LIFE-FORM OF PLANTS
The biogeographer is less connected with individual species and more
interested in plant cover as a whole.
木より森
Life-form of the plant – its physical structure, size, and shape.
Layers of a beech-maple-hemlock forest
Maple(カエデ), hemlock(ツガ), Beech(ブナ), Ash(トネリコ)
Tropical Rain Forest
Profile showing mature (ends) and building phases of the
lowland evergreen dipterocarp rain forest at Belalong, Brunei.
(Whitmore,Tropical Rain Forest)
Terrestrial Ecosystems –
The Biomes
Biogeographers recognize
five principal biomes.
Formation classes are
subdivisions of biomes
based on vegetation
structure and life-form.
Five principle biomes
- forest biome
- savanna biome
- grassland biome
- desert biome
- tundra biome
群系　ある地域で一
番発達している植生
について、それを構
成している植物の方
(生育型)に着目して
植生を類型化
生物群系
バイオーム
照葉樹は？
Vegetation types and climates
BIOMES, FORMATION CLASSES, AND CLIMATE
A generalized world map of vegetation formation classes.
- Equatorial and tropical-zone
rainforests
- Monsoon forest, savanna
woodland, thorntree-tall
grass savanna
- Subtropical evergreen
forest
- Midlatitude decisuous forest
- Cold needleleaf forest and
coastal forest
- Sclerophyll vegetation
- Tall-grass prairie
- Short-grass prairie
- Semidesert
- Desert shurub and desert
- Ice, Ice sheet
Forest Biome
Six major formations:
- low-latitude rainforest
- monsoon forest
- subtropical evergreen forest
- midlatitude deciduous forest
- needleleaf forest
- sclerophyll forest
LOW-LATITUDE RAINFOREST
Rainforest layers
Low-latitude rainforests are
very diverse, containing large
numbers of plant and animal
species. Broadleaf evergreen
trees dominate the vegetation
cover. The rainforest climates
is wet all year or has a short
dry season.
a
World distribution of lowlatitude rainforest.
World distribution of
monsoon forest.
Monsoon forest is an open
cover of deciduous trees that
shed their leaves during a
pronounced dry season. It
occurs in the wet-dry tropical
climate, ranging from South
America to Africa and
southern Asia.
熱帯季節林
雨緑林
World distribution of
subtropical evergreen forest.
照葉樹林
The subtropical evergreen forest
includes both brpadleaf and
needleleaf types and is found in
moist subtropical climate regions
of southeastern North America
and Southeast Asia. Most of this
formation class has been lost to
cultivation.
MIDLATITUDE DECIDUOUS FOREST
Midlatitude deciduous forest
consists largely of trees that
drop their leaves during the
cold season. It is characteristic
of the marine west-coast and
moist continental climate.
東京大学秩父演習林
NEEDLELEAF
FOREST
Needleleaf forest
includes boreal and
coastal forest. Boreal
forest stretches across
the northern reaches
of North America and
Eurasia. Coastal forest
is restricted to the
coast ranges of the
Pacific Northwest
region.
SCLEROPHYLL FOREST
Sclerophyll forest is
dominated by low trees
with thick, leathery
leaves that are welladapted to the long
summer drought of the
Mediterranean climate.
Southern California's
chaparral, found on
coast-range slopes, is
a form of sclerophyll
scrub.
Sclerophyll 硬葉植物
（ｼﾞｰﾆｱｽ英和辞典）
強い乾生形態をした森林
-　硬葉樹が優先し、強い
耐乾性を示す森林
（植生地理学、林一六）
Chaparral
矮性カシの木の密林
（ｼﾞｰﾆｱｽ英和辞典）
Savanna and Grassland Biomes
SAVANNA BIOME
The savanna biome is adapted to a
strong wet-dry annual cycle. Grazing
by large mammals and periodic
burning in the dry season maintain the
openness of the savanna by
suppressing tree seedlings.
雨季と乾季が特徴
ITCZ(inter Tropical Convergence Zone)の通過
Savanna woodland
Thorntree-tall-grass savanna
雨季と乾季
1988年タンザニア
GRASSLAND BIOME
The grassland biome includes tallgrass prairie and short-grass
prairie(steppe). Tall-grass prairie
provides rich agricultural land suited
to cultivation and cropping. Shortgrass prairie occupies vast regions of
semidesert and its suited to grazing.
Steppe(short grass prairie)
Tall-grass prairie
Desert and Tundra Biomes
DESERT BIOME
The desert biome includes
semidesert and dry desert and
occupies the tropical, subtropical,
and midlatitude dry climate. Desert
plants vary widely in appearance
and in adaptation to the dry
environment.
Semidesert　半砂漠
Desert 砂漠
砂漠の景観
TUNDRA　BIOME
The tundra biome
includes low plants
that are adapted to
survival through a
harsh, cold winter.
They grow, bloom,
and set seed
during a short
summer thaw.
Clinate and Altitude Gradients
CLIMATE GRADIENTS AND BIOME TYPES
Mapping Global Land Cover by Satellite
衛星観測による全球植生図の作成が可能になったのは1980年代にNOAA/AVHRRによる
GVIが作成されてからで、1985年に最初の成果がでている。
Global land cover from MODIS
ALTITUDE GRADIENT
Altitude zones of vegetation near Grand Canyon, Arizona
高度に伴う植生帯および
農作物の変化

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