Planet Earth Notes Tuesday April 1 2014 Clicker questions Growth rate is A difference between birth and death Components of life history of populations Offspring age at reproduction Natural selection Favors genotypes with high fitness Grasslands Grass supports the whole ecosystem Most dominant plant on earth Cannot kill it example weeds Found on every continent except Antarctica In every region north to the tropics Excellent food source besides for us bc there is too much cellulose For herbivores and insects Highly adaptive Spring rains summer drought snow ice Quick regeneration time Parts of grass Leaf blade outside Ligule middle Sheath bottom Grass adaptations Protective sheath at ground level Grow from the base not the tip Deep roots 4 11 ft deep advantage is finding water during a drought unique ability prevent grazing animals from pulling roots out of the ground Narrow leaves minimize water loss Soft stems allow plants to bend not break in the wind Grass is very resilient Animal adaptations Cryptic coloration is the way to adapt because there are no places to hide so much blend in with environment Wide paws able to burrow underground to create housing May wander long distances to find food and evade predators Adapted to dry windy conditions Trophic Cascade is another word for the food web Clicker question All grasslands are the same everywhere T F False Three Types of Grasslands Temperate grasslands that are influenced by winter Prairie s and steppes Located in temperate regions Tropical Savanna Located in tropical regions Tundra Located near the north pole Temperate Grasslands South America more towards the Atlantic Stable for long periods of time Intermittent rainfall 10 to 20 inches per year drought is common Natural fires are common Fertilize soils absorb heat in winter No trees due to Drought and fire Grazing herbivores Prairie Usually humid Nutrient rich soils Densely covered with grasses Simple food web Primary consumer grasses Secondary consumer herbivores Predators Simple Food Web Vegetation Herbivores Eat vegetation Carnivores Eat animals including insects Steppe Always located near mountains They block rain Very drought prone Drier than the prairies Grass is much shorter and less dense because there is less evaporation Populated by the same types of animals but some different species Herbivores and carnivores Soil is less rich Tropical Savanna Southern hemisphere More rain than the temperate grasslands 50 inches per year Severe extended drought Cuts down in amount of trees that can grow Tundra Cold windy very short growing season Soil is mostly saturated because of melting snow and ice Major carbon sink Everything we burn sinks there Low biodiversity because of the cold weather and long cold seasons In terms of animals insects and plants Nesting ground for many birds DVD Notes Grass covers a quarter of all the lands of the earth Mongolian gazelle gather once a year because they have their young Nearly all of them give birth within 10 days Safest way to have young but impossible to avoid predators Only thing to hide from predators in is grass Without trees eagles have to nest directly on the ground and they are exposed Gazelles face the danger of moving to new pastures and leaving the rest behind them Grass is almost indestructible because it grows from a protective part that grows at the base of its stems Able to prepare and reproduce rapidly and feeds more wildlife than any other plant Take 5 hours to pass overhead because the flock is so large Red billed quelea 2 million wildebest in African savannahs grass manages to grow in the bitter conditions of the artic temperatures rise and the grass that was dormant grows and the artic is green artic tundra size of Australia Snow geese 5 million birds fly to the tundra Touch down into their artic circle which are their traditional breeding grounds Mates are in short supply and disputes can be vicious For a short period the tundra is ideal and there are fewer predators and the grass grows rapidly Not many predators so most of the time geese are safe to nest on the ground The predator that feeds on geese is an artic fox Impossible to sneak up unnoticed stashes the eggs she does obtain since the geese are only there for a short period time Bigger predators in the south of the tundra wolves Caribou travel 30 miles a day can cover 2000 during the summer months Wolves will starve if they don t find the caribou but hard to locate prey that never stops traveling Caribou needs new pasture which is what drives the migration Scares the pack and singles out the young