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Notes 2/4

– First midterm: Tuesday 2/15/10

• Less than 2 weeks from Today

Tree-Ring Dating Activity: Due Today

---returned on Tuesday

• BOOKS O’ DAY-- today

Forest Shreve Joseph Krutch Ed Abbey

Southwest Desert

• What is a desert?

• World deserts and why

• North American Deserts

• Sonoran Desert

– Plant life form diversity

– Ethnobotany

• Van Dyke (1901): “Deserts … are the breathing spaces of the West and should be preserved forever.”

• http://web.bio.ed.ac.uk/research/groups/jdeacon/desbiome/

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• If evaporation:precipitation >....:….. desert

– Tucson: ….:1

– Yuma: 30:1

– Sahara: 600:1

– North slope Alaska: …..:1, maybe

• Causes of evaporation:

– High solar radiation

– Dry wind

• Tucson is a desert, ………. not.

What is a desert?

• Precipitation is …………..

– High year-to-year ………….

– Lower the mean, higher the variability

• Huge ………………. variation

– Diurnal swings: 50° F, especially

during dry winter days.

Weather of a Desert?

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Atacama Kalahari Great Sandy

……………………. deserts---- Painted Desert, AZ

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Desert Plant Adaptations

Food/Water Storage--In stems

--deep bulbs

Food/Water ConservationSpines NOT leaves

Small leaves/shedding

Waxy bark/leaves

Food/Water CapturePhotosynthetic bark

Shallow roots (cactii)

Deep roots (trees)

(Structure)

Desert Plant Adaptations(………….

)Dormancy

(sometimes

years)

Short life cycles

--annuals/perennials

……………..

--nurse trees

The sun goes down, and nightfall bringsAll manner of night-flying things

The screech owl and the nectar bats,Nighthawks showing off like acrobats

Waggin, 1969. U of Arizona press

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Chomp!!

Forrest Shreve

• 1878 (Maryland) –

1950 (Tucson)

• Plant ecologist,

Jamaica, NY

• 1908: arrived in

Tucson

• Traveled

everywhere, always

observing

Tumamoc Hill

• T.O.: Horned

Lizard

• By “A” Mt.

• 869 acres,

“protected”

• Unique: to

study deserts

• Tucson gem

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Shreve’s Desert Plant Life Forms (25)

• ………, ………. ephemerals (wildflowers)

• Leaf succulent perennial (agave)

• Plant succulent

– Unbranched (barrels)

– Tall (……………….)

• Plant not …………….

– Specialized stems (ocotillo)

– Stems ………. (palo verde)

– Leaves small (mesquite, ironwood)

Great Basin

Mojave

Chihuahuan

Sonoran

Great Basin Desert190,000 sq. miles

(most northerly, largest)

Elevation: 3000-6000’

Moisture: ………. (even)

(4-8in)

Temp: ……

Plants:

One layer

Few forms

---………….

--rabbitbrush

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Mohave Desert

22,000 sq. miles

(smallest)

Elevation: 2500-6000’

Moisture: ………. dominant

(<5in)

Temp: ……....

Plants:

1-1/2 layers

Few forms

---…………….

Chihuahuan Desert

140,000 sq. mi

(most southerly)

Elevation: 1000-4000’

Moisture: ……… dominant

(3-12in)

Temp: …….

Plants:

One layer

Few forms--……….

--cholla

cactus

Sonoran Desert

100,000 sq. miles

(most diverse)

Elevation: 1000-3500’

Moisture: ………….l

(5-13in)

Temp: ……….

Plants:

……… Layers

Many Forms:

--…………..

--Mesquite--Agave

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Desert Comparison

S

Warm Cold

Bi-

modal

Uni-

modal

Temperature

P

r

e

c

ip

i

t

a

ti

o

n

…………..

……….(winter)

………..

…..

………..(summer)

The gecko said, “I fail to seeWhy people think you look like me

I wish they’d take a better lookSo I won’t so often be mistook.”

C. Waggin, 1969. U of Arizona Press

• Most interesting desert in the world

because of vegetation (McGinnies)

• Most …………..of ANY desert in world

• 2000 species of plants

• 550 species of vertebrates

• Unknown thousands invertebrate species

– 1000? bee species

– ???? beetle species.

Sonoran Desert Biodiversity

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Native Food Stuffs Enough?

• ……………. dependency

• Food storage?

• Can be supplemented with wild meat

• …………food might be nice supplement

– What about ……………..

– Caliche

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