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the largest population that an environment can support over a long period of time
scarce food, water, etc; when the population is greater than the carrying capacity, limiting factors will cause the population to shrink; due to limited resources, organisms sompete with each other, across and within species
a long-term change that takes place in two species because of close interactions with one another
a stable, mature community that undergoes little or no change in species over time
the breaking down of plant water by fungus and bacteria further add carbon to the environment
temperate deciduous forest
has plenty of rain; big seasonal differences; trees lose their leaves in the winter to conserve water; diverse plant and animal life
less seasonal differences than temperate forest; evergreen and needle trees; less diverse plant and animal life; few plants on the ground
tropical rain forest
much rain, little seasonal temperature variation; most diverse biome of all; poor soil
vegetation is mostly grass; many large plant-eating mammals live here; loads of large herbivores live here
hot, dry; plants have shallow root systems; animals are well-adapted (they store water, live at night, etc.)
consists of carbon dioxide in the air (which comes from animal respiration and the burning of fossil fuels) going through photosynthesis, respiration, and decomposition
when nitrogen in the air (most air is nitrogen, but most living things can't use it) goes through nitrogen fixation (turns it to bacteria), and then the bacteria break down dead organisms and put nitrogen back into the air
food web vs. food chain
the food web is more accurate than the food chain because with the food web, you can see multiple animals/plants that eat or are eaten by another, while the food chain just shows one organism eats one more, which eats another, which eats another, and so on
when things start to live where there was previously no life; consists of pioneer species adding levels of soil, moss growing and dyingonce the soil is deep enough, the dead moss adding soil, ferns replacing the moss, ferns are replaced by grasses, and when the soil is thick enough, small trees and eventually forests grow
example: lichens need little or no soil, but as they die, they add to the soil level
occurs when an existing community is destroyed by a natural disaster, or if a farmer stops growing crops (the difference is that soil already exists and the original community regrows); consists of grassy weeds growing, thicker weeds and more bushes grow, small needle trees grow, and then hardwoods grow
consists of weeds growing in the water, and as they die, soil is added (eventually the pond fills up); the pond becoming a wetland full of grasses and weeds; shallow rooted trees, such as pines, grow; hardwood trees, like oaks, grow slowly but taller, and eventually shade out the pine trees and form a hardwood forest (which is the most common climax community in PA)
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