Download The grassland biome - Whitman Middle School

What is grassland?
The grassland biome
Grasslands are characterized as lands
dominated by grasses rather than large shrubs
or trees. In the Miocene and Pliocene Epochs,
which spanned a period of about 25 million
years, mountains rose in western North
America and created a continental climate
favorable to grasslands. Ancient forests
declined and grasslands became widespread.
Following the Pleistocene Ice Ages, grasslands
expanded in range as hotter and drier climates
prevailed worldwide.
A grassland west of Coalinga, California.
Source: http://www.ucmp.berkeley.edu/exhibits/biomes/grasslands.php
2.
Savanna
Savanna is grassland with scattered individual trees. Savannas of one sort or another cover
almost half the surface of Africa (about five million square miles, generally central Africa) and
large areas of Australia, South America, and India. Climate is the most important factor in
creating a savanna. Savannas are always found in warm or hot climates where the annual rainfall
is from about 50.8 to 127 cm (20-50 inches) per year. It is crucial that the rainfall is
concentrated in six or eight months of the year, followed by a long period of drought when fires
can occur. If the rain were well distributed throughout the year, many such areas would become
tropical forest.
In Africa, a heavy concentration of elephants in protected parkland have created a savanna by
eating leaves and twigs and breaking off the branches, smashing the trunks and stripping the
bark of trees. Elephants can convert a dense woodland into an open grassland in a short period of
time. Annual fires then maintain the area as a savanna.
Savanna has both a dry and a rainy season. Seasonal fires
play a vital role in the savanna's biodiversity. In October, a
series of violent thunderstorms, followed by a strong drying
wind, signals the beginning of the dry season. Fire is
prevalent around January, at the height of the dry season.
Fires in savannas are often caused by poachers who want to
clear away dead grass to make it easier to see their prey.
The fires do not devastate the community. Most of the
Savanna in the Samburu Game Preserve,
animals killed by the fires are insects with short life spans. A
Kenya.
fire is a feast for some animals, such as birds that come to
sites of fires to eat grasshoppers, stick insects, beetles,
mice, and lizards that are killed or driven out by the fire. Underground holes and crevices provide
a safe refuge for small creatures. Larger animals are usually able to run fast enough to escape
the fire. Although the dry stems and leaves of grasses are consumed by fire, the grasses' deep
roots remain unharmed. These roots, with all their starch reserves, are ready to send up new
growth when the soil becomes more moist.
A fire leaves scorched earth covered with a fine layer of powdery black ash in its wake. During
March, violent thunderstorms occur again, this time heralding the rainy season. When the rains
come, savanna bunch grasses grow vigorously. Some of the larger grasses grow an inch or more
in 24 hours. The savannas experiences a surge of new life at this time. For example, many
antelope calves are born. With so much grass to feed on, mothers have plenty of milk. Calves die
if the rains fail to come.
Other animals (which do not all occur in the same savanna) include giraffes, zebras, buffaloes,
kangaroos, mice, moles, gophers, ground squirrels, snakes, worms, termites, beetles, lions,
leopards, hyenas, and elephants.
There are also some environmental concerns regarding savannas such as poaching, overgrazing,
and clearing of the land for crops.
Source: http://www.ucmp.berkeley.edu/exhibits/biomes/grasslands.php
Kangaroo Rat
http://www.worldbookonline.com/student/article?id=ar294780&st=kangaro
o+rat
Animal Guide: Giant Kangaroo Rat
Giant Kangaroo Rat (Dipodomys ingens)

Type: Mammal

Family: Heteromyidae

Habitat: Sandy, arid grasslands

Location: Western central California

Diet: Seeds and grains

Average lifespan in the wild: 9.8 years

Size: Head and body 6-7.8 in (15-20 cm); tail 7-8.5 in (18-21.5 cm)

Weight: 3-6.3 oz (93-195 g)
Giant kangaroo rats are aptly named—they bound across California grasslands with their elongated hind legs and feet. Their long tail
is used for balance, and their short neck and large, flattened head help giant kangaroo rats travel almost exclusively via bipedal
motion. The erratic path of their powerful jumps and top speeds of almost 10 feet per second makes them very hard for predators to
catch.
Giant kangaroo rats live alone in underground burrows on sandy slopes. Inside each borrow
they keep a large cache of seeds and grains. The rats are nocturnal, coming out every night after
sunset to gather more seeds and grains into large expandable pouches in their cheeks to carry
back to the burrow. Any seeds or grains that are not completely dried are buried outside the
burrow under a thin layer of sand and left to dry before adding to the food hoard. Foraging trips
are short. Giant kangaroo rats are very territorial and never leave their den for very long, usually
only a total of 15 minutes per day.
Even though giant kangaroo rats are a solitary species, individuals do communicate with each
other using scent as well as foot thumping, a behavior in which the rats hit their hind feet
against the ground repeatedly. An array of specific signals are used, from single, short thumps,
to long, elaborate “footrolls” that can average over 100 drums at 18 drums per second. Foot
drumming helps identify neighbors, establish territory, and communicate mating status. Giant
kangaroo rats will also approach snakes and foot thump at the predators in an attempt to drive
them away.
Giant kangaroo rats are a critically endangered species, restricted to a small area in western
central California that is only about 2 percent the size of its former range. Urban and agricultural
development in California has caused massive habitat fragmentation, which means the
remaining populations will probably become genetically isolated. However, giant kangaroo rats
are listed as a state and federal endangered species, and protected lands and policies are in
effect to help save the species.
Did you know: Giant kangaroo rats have the most concentrated urine of any North American
mammal. Their kidneys are so efficient that they do not need to drink—they get enough water
from the seeds they eat.
Photo by George Harrison, U.S. Fish and Wildlife Service
Source: http://www.pbs.org/wnet/nature/interactives-extras/animal-guides/animal-guide-giant-kangaroo-rat/2196/
Giant Kangaroo Rat Defending Territory – a 30 second video
http://www.arkive.org/giant-kangaroo-rat/dipodomys-ingens/video06.html
Source: http://www.exploringnature.org/graphics/mammals/kangaroo_rat_diagram.jpg
Giant Kangaroo Rat Range
Source : http://www.sibr.com/mammals/M106Range.gif
California
Counting Rats from Space
The Nature Conservancy is working with University of California Berkeley researchers
and partners at Carrizo Plain National Monument to count and map giant kangaroo
rat populations using satellite remote sensing data.
Giant kangaroo rats are the keystone species of Carrizo Plain. A keystone species is
like the centerstone in an arch — even though it’s one small stone, it keeps the whole thing
standing up.
And when a keystone species is in trouble, the rest of the ecosystem soon will be, too.
That’s why keeping track of this endangered rodent is so critical. Scientists and resource
managers base important land management decisions on the size and distribution of
each year’s kangaroo rat population, says Conservancy ecologist Scott Butterfield.
Nature’s Lawnmower
The giant kangaroo rat, found only in Central California, is nature’s lawnmower, clipping
the grass and creating the preferred low-profile habitat — short, low-to-the-ground plants —
of other endangered San Joaquin Valley species, including the kit fox, blunt-nosed leopard
lizard and antelope squirrel.
About the size of an orange with a tail twice as long as
its body, kangaroo rats clip the grasses around their manyroomed burrows or “precincts.”
They then pile up the grass clippings in neat, near-perfect
circles at the entrance of their burrow, waiting for the grass seeds to cure in the sun before
storing them.
A benefit of these mini-compost piles of clippings is an enriched soil. Plants,
particularly the California jewelflower, can be three to five times more productive when
growing where the stacks have been.
As Butterfield says, “The giant kangaroo rat is the ecosystem engineer of the Carrizo Plain,
clipping the grass, creating the burrows and enriching the soil that provides the conditions
necessary to support a full suite of endangered species.”
Counting Giant Kangaroo Rats – the Hard Way
In the past, the Bureau of Land Management tried estimating the kangaroo rat population by
trapping them across the Carrizo Plain. This proved too expensive, time consuming and
difficult to accomplish each year across their 150,000-acre habitat.
Next, the Department of Fish and Game tried estimating the extent of giant kangaroo rats
across the Carrizo Plain by conducting aerial surveys. Most years it’s easy to spot a giant
kangaroo rat precinct, even from the air, by the almost perfect circles they create while
clipping.
But this approach also had its shortcomings.
“While these efforts produced important information about population distribution, the
resulting hand drawn maps were not precise enough to allow annual management
decisions to be made,” says Butterfield.
When there’s a lot of grass and not a lot of kangaroo rats, managers must decide whether to
bring in cattle for grazing or do a prescribed burn in order to achieve the low-profile habitat
that the rats maintain.
“Plus," continues Butterfield, "the process was too dependent upon the skills of each
surveyor — making it nearly impossible to accurately repeat the process year after year.”
Satellite Imagery of Giant Kangaroo Rat Populations
Each dot represents one "precinct" or home. Because the rats live alone, each dot
also represents one rat.
Satellite Data Makes It Faster, Better
Enter satellite remote sensing data. Butterfield says
using satellite imagery allows giant kangaroo
rat precincts and their population extent to be
mapped accurately across the Carrizo Plain each year in a precise, quantifiable, repeatable,
fast and cost-efficient way.
To map kangaroo rat precincts, images are taken in spring before the kangaroo rats begin
clipping and again in summer when their work is done and their grass piles are complete.
Butterfield says that by using satellite remote sensing data scientists can more accurately
predict the distribution of kangaroo rats and increase our understanding of the crucial role
they play in their environment.
This information is of paramount importance as we try to understand what impact
climate change might have on the environment.
“We can begin to track their response to change," says Butterfield. "If the giant kangaroo
rats begin to have trouble, other species will, too. This data will help us know more about
the effects that climate change might have to other threatened and endangered species at
the Carrizo Plain.”
February 26, 2011
Source: http://www.nature.org/ourinitiatives/regions/northamerica/unitedstates/california/explore/counting-ratsfrom-space.xml
Source : http://thomphelps.files.wordpress.com/2009/07/snaring_kangaroo_rat_web.jpg?w=490