Scioly Ecology 2018: Desert and Grassland

xerocoles

animals that can live in deserts

erg

sand dune region

largest desert in the world

antarctica - 5.5M square miles

also largest cold desert

xerophytes

desert plants

map of deserts

plus antarctica and arctic?

area of earth w/ desert

1/5 of earth's land

hottest temp ever

54C in death valley and also in kuwait

desert defn

less than 10in (25cm) of rain per year

where do grasslands form

in areas where too little precip for forest but too much for true desert

aridity index

A = P/PET = average annual precip/potential evapotranspiration

<0.05 = hyperarid

0.05-0.20 = arid

0.20-0.50 = semiarid

generalizations about grassland plant species

grasses of multiple species and genera but mostly dominated by a few species

most with rhizomes (underground spreading stems that send up shoots and nodes and store starches up to 1/2 of biomass); wind pollination; perennial bunchgrasses

will grow back after fire, grazing, wind, extreme temp

temperatures in grasslands

huge range from seasons often deep into the negs in winter (more to north), over 100 in summers

grassland precipitation

6-40in (15-100cm)

grassland precipitation season

scattered thunderstorms in summer but most rain/snow in winter and cooler times

grassland soils

mollisols (basic, hummus rich, dark, productive, Ca/Mg)

mollisols are most common soil type in US (21.5%) and 7% of ice free land worldwide

found in W great plains and scattered rest of west

grassland growing season

typically 120-200 days

grasslands topography

flat, some rolling hills, steep canyons

grasslands fire

frequent due to summer thunderstorms

necessary to maintain ecosystem and keep back trees and shrubs, grasses have survival mechs

grasslands fauna

grazing animals like deer, elk, bison in large herds

songbirds and small burrowing mammals very common

tallgrass prairie

usually around 1-3m (3-9ft), deep roots, nearest eastern deciduous forests

precip around 25-40in (65-100cm), usually around 34in

Tallgrass prairie problems

most plowed and planted w/ wheat/corn; increased drainage and runoff reduces moister areas

Tallgrass prairie plants

Big bluestem (image), sand bluestem, indian grass, slough grass, switchgrass

mixed grass prairie

usually under 4ft (1.3m) in height; usually around 3ft

precip around 14-25in (35-65cm)

mixed with taller grasses growing in slightly wetter areas and shorter ones in drier areas

mixed grass prairie species

little bluestem grass, june grass, needle grass, dropseed grass, wheatgrass, wild rye

mixed grass prairie problems

almost entirely planted over with crops such as corn and soybean

shortgrass prairie

nearest to western deserts, cover most area of the 3 groups in N america; mostly W of latitude 100W

most less than 20in (50cm), usually below 1ft; fewer forbs because lower rain favor grasses; can't grow bigger bc no water

precip usually around 14-10in (25-35cm)

also called 'the plains'

shortgrass prairie problems

some takeover for irrigated corn and crops; mostly just overgrazed for cattle, fenced from native grazers, invasives on ranges

shortgrass prairies species

buffalo grass, galleta grass, needle grass, grama grass, penn sedge

bunchgrass prairie

also called palouse prairie (near palouse river in WA)

found in plains N of great basin, colorado, UT, CA, WY, MT

bunchgrass prairie species

purple needlegrass, sagebrush, bluebunch wheatgrass

bunchgrass vs. typical plains grass

bunchgrass sends up new shoots from its base forming a clump

Most prairie grasses have mat-like roots that spread and produce new shoots spread out from one another

characteristics of grassland grazers

wide set eyes, large herds, camoflage and speed, good vision,

characteristics of grassland birds

lots of them (lots of songbirds)

strong fliers due to high winds, nest in tall grasses,

characteristics of small grassland mammals

many in colonies, many burrow, many hop for visibility

desert soils

aridisols (parent material with buildups of minerals that would usually be leached like calcium carbonate)

SW and great basin; 8% of US, 12% world

some entisols (indistinguishable from parent material in W)

very little hummus but high in nutrients

grassland history

during pleistocene/miocene (50-3.5MYA) mountains in N amer make grassland climate more favorable

after pleistocene ice ages, drier/warmer climate expand grasslands

savanna

tropical grassland with few uniformly dispersed trees that aren't dense enough to form a closed canopy

savanna reqs

20-50in of rain concentrated in 6-8 months followed by long hot drought where fires are common; average daily temp never drop below 64F

types of savanna

climactic savannas - classic all rain in one season and fire and drought maintain in rest of year

edaphic savannas - thin or clay soils that inhibit tropical forest growth

derrived savannas - human or elephant deforestation creates critical mass of grass to burn away tree sprouts

savanna plants

generally has a dominant grass or few grass/forb species and scattered deciduous trees

grasses: includes elephant grass which is like 10ft

trees: acacia, baobab, candelabra

savanna seasons

winter is dry starting October with strong winds, little rains, few lightning

summer is wet

savanna fires

during winter dry season

small animals in burrow, big out run, insects die, grades burn but roots ok

savanna problems

desertification, clearing for farming, poaching, overgrazing

grassland problems

clearance for farming/grazing, species disruption (poaching and overhunting/invasives), hunting

savanna locations

brazillian horn highlands, venezualan campos, sahel (lot thicker than shown), E africa and S africa, parts of india and SE asia; N australia

Derived savanna

much of the world's savanna is actually tropical forests that were cleared by people and then animals and fire maintained the grasses

veldts

grasslands of South Africa

puszta

grasslands of Hungary

temperate grasslands definition

clearly defined hot summer and cold Winters

temperate grasslands distribution

plains of US, pampas in Argentina, eurasian steppes from ukraine through balkash, mongolia and manchuria area, turkey

rainfall in temperate grasslands

moderate: 20-35in per year (more rain is taller grass)

mostly late spring early Summer

temperate grasslands soil

mollisols dark and Rich

savanna soils

rich ish but often leached

temperate grasslands fire

there is some fire in the drought season in fall or summer, but not as much or as important as savannas

temperate grasslands seasons

very hot summer and cold winter

rains in late spring and early Summer and drought for the rest of the year

trees in temperate grasslands

some riparian but basically nonexistent in actual grass unlike savanna

temperate grasslands Max and min temperatures

max over 100f min like -40

temperate grasslands problems

destruction for farming and grazing

steppe rain

10-20in in winter (30-50cm)

steppe problems

wheat and grazing destroying it, salinization from irrigation

desert fires

uncommon, most of the time there isn't enough vegetation

flash flooding mechs

earth is hard baked so all the water just runs off immediately after it falls

desert types

hot and dry

cold

coastal

semiarid

hot and dry desert

little rain but varies

mean temps 20-25C; often over 40C; can drop into -C

plants w/ thick cuticle and sometimes CAM; small animals (lizards mostly)

include major N amer deserts of mojave-chihuahua-sonoran-great basin, sahara, australia

semiarid desert

cooler (20-25 in summer, 10C at night, cooler winters); precip varies but more dew and condensation

gravelly in hills with hardpan bottoms

plants are larger shrubs like creosote; brickelbrush; somewhat more animals (small mammals)

cent asia, great basin, montana

precip in deserts

under 25cm; most in cool winter; precip varies but always low

coastal deserts

cool (15-20C in summers) summers and moderate winters; very little precip, often years between

atacama and namib

very dry adapted animals and plants

cold deserts

cold (below freezing winter, 20C in summer); higher precip (15-25cm) mostly as snow in winter; moister

higher elev great basin, antarctica/arctic

silty soil

the sun and deserts

lack of moisture means 90% of solar radiation hits ground vs. 40% in humid/tropical

bajada

alluvial fans merge into a gradual slope from mountains in desert to base

different names for grasslands

pampas, prairies, meadows, steppes, savannas, veldt,

largest intact savanna

N australia

list savanna types

tropical, temperate, mediterranean, montane, flooded

tropical savanna

synonymous with typical savanna

temperate savanna

sketchy term to describe any temperate grassland with sparse trees and shrubs

mediterranean savanna

savannas in mediterranean climates with interspersed trees (med, socal)

ie: oak savannas

flooded savannas

usually tropical savannas that are flooded part of the year like the pantanel or the okavango

alpine savanna

or montane savanna; found above the tree line high up in equitorial areas, elsewhere is just alpine grassland; same as alpine tundra?

alpine grassland

found above the treeline or polar direction from treeline but not in permafrost

mostly tussock fescue grasses where temperature never tops 50F in summer

drops 6.5C for every thousand feet up of 3 degrees?

successional grasslands

grasslands maintained by fire and grazing and disturbances that would otherwise be taken over by trees and shrubs

temperate vs. savanna

mostly by distance from equator (savanna usually between tropic of capricorn and cancer)

savannas have trees and shrubs while temperate typically little to none

climate: rains and temps

savanna woodland

tree canopy covers >50% of area

savanna parkland

20-50% of area is covered by tree/shrub canopy

savanna grassland

<20% of the area is covered by trees/shrubs

prairie

name given to US grasslands

california grasslands

used to be sagebrush steppes in owens valley and NE and stipa pulchra (purple needlegrass) bunchgrasslands through central and Socal

bunchgrasses disappeared

steppe

refers to european grasslands; treeless entirely; dry (30-50cm); drought common, feather grasses dominant (feathery flowers, mostly stipa); cold winter, moderate summers where they get most of rain; grasses die back in august and don't revive until spring

steppe climate

dry (30-50cm); drought common summer-autumn; precipitation distributed with rain in summer and some snow in winter but dries out fast in summer rains

cold winters below freezing for 5 months; moderate summers up to around 70's (F)

steppe plants

dominated by feather grasses (stipa sp); fescue (festuca), oats (avena), sedges (carex), bluegrass (poa bulbosa), tulips (tulipia), sagebrushes (artemisia)

forest steppe

where the steppe meets the northern boreal forests in a transition zone where trees more and more dense as north; N of meadow steppe

meadow steppe

moister climate; more sedges and feathergrasses (needlegrasses/stipa), often used for livestock

south of forest steppe, north of dry steppe

Dry steppe

ground is dry most of the time because rainfall less than amount that can evaporate; mostly shorter feathergrasses/needlegrasses and fescues

merges with desert to south and meadow steppe to north

types of steppe

forest steppe: as steppe merges with taiga to north

meadow steppe: wetter steppe S of forest steppe

Dry steppe: drier steppe merging into deserts

pampas

south american grasslands in rio de la plata region, Uru and Arg mostly

pampas climate

warm summer about 30C and cool winter around 15C; rain varies from 20-40in

sterile pampa

dry plain that can give way to deserts; found to western portion up towards andes; salty soil; dominant plants are thornbrushes (ie: chanal); rain around 20in

eastern pampas

wetter side closer to sea around 30-40in precip; very productive ag land; dominated by pampas grass (same one invasive in CA), few forbs inbetween but pretty dominant; high fire frequency kills most trees except ombu

veld

extends high into mountains; mostly in E S africa and lesotho; rain 20-40in

types of veld

high veld towards central in high elevation areas

bushveld is dry savanna-like

cape middle veld is to west of high veld in the middle of S africa

sweet veldt is areas with <25in rain where grasses retain nutrients through winter

sour veld is wetter areas where pull in water during winter dry season

veld plants

dominated by red oat grass; bermuda grass, others; mostly taken over by crops like corn now