Grassland (Prairie, Steppe)Places near the middle of Asia and North America
do not get enough rain to grow trees. Rainier areas have tallgrass prairies, and drier places have
shortgrass steppes. Most grasses make masses of roots
to gather water; decaying roots make soils dark and fertile.
Grazing animals are common; fires occur in dry times. EndFragment
TundraPlaces around the Arctic Ocean have long summer days,
but the sun never rises very far above the horizon.
It doesn’t get very warm, and the soil stays frozen. These conditions support a cover of cold-tolerant plants,
flowers that grow and make seed within a few weeks,
and animals that migrate in during the short summer. EndFragment
Tropical and Rainshadow DesertPlaces get very little rain if they are near the Tropic lines
or are surrounded by high mountains. These conditions support plants that are adapted to survive
in dry, rocky, and salty soil. Some plants (like cactus)
can store water. Others can grow quickly, flower, and
make seed in just a few weeks after a rare rain.
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[endif]EndFragment
Boreal Forest (Taiga)Places up near the Arctic Circle in Asia and North America
have long, cold winters and short summers. These conditions support slow-growing needle-leaf trees
(called evergreen because some needles stay all winter).
Fallen needles add acid to the thin, cold soil,
making it even less fertile for other plants.EndFragment
Deciduous ForestPlaces 35-40 degrees of latitude away from the equator
near the east coasts of continents have rainy summers
and cool winters, usually with some snow. These conditions support a cover of deciduous trees,
like oak, birch, and maple, with leaves that change color
and fall to the ground before winter comes. EndFragment
Equatorial RainforestMost places near the equator have high temperatures
and plenty of rainy days in every month of the year.These conditions favor the growth of dense forests
with a wide variety of fast-growing trees and birds,
monkeys, snakes, other animals that live in trees,
and many insects (which often carry diseases). EndFragment
Chaparral (Maquis, Garrigue)Places 35-40 degrees of latitude away from the equator
near the west coasts of continents have hot, dry summers
and cool, rainy winters. Dry-season fires are common. These conditions support a cover of low trees and shrubs
that are able to tolerate fires, along with other plants
that can grow back quickly after the fires.EndFragment
Grassland
Chaparral
Desert
with clickable maps, presentations, videos, chapters and activities
Savanna
Rainforest
Tundra
The movements of plant nutrients
(calcium, magnesium, phosphorus, etc.)
in different biomes of the world
are controlled mainly by climate
Click on the labels on this map
to see the nutrient cycle
for each major biome.
Boreal Forest
Deciduous
Forest
Tropical SavannaMost places between the equator and the Tropic lines
are hot all year, with rainy summers and dry “winters.”These conditions favor grasses, shrubs, and small trees.
The number and size of trees depends on the length
of the rainy season and the frequency of fires.
Large herds of grazing animals are also common. EndFragment
Grassland Both
Tiaga
Grassland
Deciduous Color
Chaparral Both
Chaparral
Desert Color
Rainshadow Both
Deciduous Both
Savanna Color
Desert Both
Rainshadow Color
Savanna Both
Mountains
Savanna
CLEAR
MAP
Latitudes
Rainshadow Desert
Tropic Lines
Tundra
Continent Green
Tundra Both
Deciduous Forest
Continent Tan
Tundra Color
Rainforest Color
Equator
Tiaga Color
Rainforest Both
Tiaga Both
Rainforest
Grassland Color
Chaparral Color
Year 2 Totals:
Year 3 Totals:
Year 4 Totals:
Year 5 Totals:
Soil
Totals After 1 Year
Biomass
Soil Biomass Litter
Litter
amount
0
Rainin
Decay
percent
Rockin
Calculate
ENTER the TRANSFER RULES between the parts of the system
ENTER the STARTING AMOUNTS in each part of the system
Leach
Runoff
Uptake
Fallout
Hover over any arrow on this diagram
to see how these climate conditions
influence the movement of nutrients
between parts of this ecosystem.
Return To
World Map
Loss in runoff – small to medium. The soil is thin and rocky; it cannot absorb much water, so there is some runoff.
EndFragment
Uptake from soil – small. The sun may still be up at midnight, but it doesn’t get very high up. Soil stays cold; plants grow slowly.
EndFragment
What Does
This All Mean?
Loss by leaching – very small. In permafrost (frozen subsoil), very little water can seep down through the soil.
EndFragment
Input from rocks – very small. Chemical processes go very slowly in places that are so cold that the subsoil stays frozen.
EndFragment
Fallout from biomass – medium/high. Grazing animals quickly eat most of the plant growth every year, and return the nutrients to the litter.
EndFragment
Input from rain – small. Cold air cannot hold much water; small amounts of rain or snow can’t bring much nutrient in.
EndFragment
Decay from litter – very slow. Decay micro-organisms work very slowly in the cold soil, which is frozen most of the year.
EndFragment
Input from rain – small/medium. Every raindrop or snowflake forms around a tiny bit of dust or salt. Input is small where rain can fall only during the short summer.
EndFragment
Return to
World Map
Loss in runoff – small. Runoff-causing storms are rare during the short summer. Melting snow in the spring can take some nutrients away.
EndFragment
Boreal Forest
Uptake from soil – small/medium.Plants cannot grow very fast in places where winters are long and very cold.
EndFragment
Loss by leaching – small. Very little water can seep down when the soil is frozen in winter; The summer is too cool and short for much leaching to occur.
EndFragment
Fallout from biomass – medium. The trees are called evergreen because needles stay on all winter, but some break, fall off, or are eaten.
EndFragment
Input from rocks – small. Chemical processes go very slowly in places with long, cold winters and soil that is often frozen.
EndFragment
Decay from litter – very small. Micro-organisms work very slowly where the ground is usually cold, and winter snow melts very slowly.
EndFragment
Input from rain – medium. Every raindrop condenses around a tiny bit of dust or salt.Rainfall here is generally lower than in the equatorial rainforest.
EndFragment
Uptake from soil – medium. Trees grow about half of the year, so they generally take up about half as many nutrients as in the equatorial rainforest.
EndFragment
Loss in runoff – medium. Water from spring snowmelt and summer thunderstorms can run downhill to streams and eventually to the ocean.
EndFragment
Fallout from biomass – medium. The trees are called deciduous, because their leaves turn color and fall before winter comes.
EndFragment
Decay from litter – medium. With hot summer and cold winter, and a medium amount of rain what else should we expect?!
EndFragment
Input from rocks – medium.With hot summers and cool winters, the average annual temperature is between the hot rainforest and the cold boreal forest.
EndFragment
Loss by leaching – medium. Water seeps down through soil in spring and fall, when the trees do not have a full set of leaves.
EndFragment
Loss in runoff – small. Grasses tend to absorb all of the available water. Runoff is likely only if a storm comes soon after a fire.
EndFragment
Uptake from soil – small/medium. Grasses can grow quickly after occasional rains, BUT they do not take as much nutrient as trees can in a rainier climate.
EndFragment
Return To
World Map
Fallout from biomass – large.A large percentage of biomass goes to the litter each year, either through grazing animals or fires in spring or late summer.
EndFragment
Decay from litter – medium. Grassland soils are thick and dark, because they have a large amount of partly decomposed grass roots.
EndFragment
Input from rocks – small/medium. Chemical processes go slowly because the ground is usually dry and winters can be cold.
EndFragment
Loss by leaching – small.The dense masses of grass roots are able to capture nearly all of the water that the soil has in this semi-arid climate.
EndFragment
Input from rain – small. Every raindrop condenses around a tiny bit of dust or salt. Grasslands occur in places that do not get enough rain for trees.
EndFragment
Decay from litter – medium. Worms and soil microorganisms become active in the warm soil when it gets rain in early winter.
EndFragment
Input from rocks – small. Chemical processes go slowly where summers are very dry and winters are rainy but cool.
EndFragment
Loss by leaching – small/medium. Plants can take up much of the water that comes in the winter rains. Some can seep down through soil and carry nutrients away.
EndFragment
Input from rain – small. Every raindrop condenses around a tiny bit of dust or salt. Winter is the rainy season, BUT cool air does not hold much water.
EndFragment
Loss in runoff – medium. Winter rains are gentle, BUT cool air can’t evaporate much water. This leaves more water to run off, especially after a fire.
EndFragment
Uptake from soil – small. Plant growth is limited by lack of water in summer and the cooler temperatures and lower sun in winter.
EndFragment
Fallout from biomass – medium. Grazing animals take nutrients from biomass and transfer them to the ground. Fires at the end of the dry summer do the same.
EndFragment
Uptake from soil – small.Plants cannot grow fast in places where there is very little water in the soil
EndFragment
Loss by leaching – very small. Water rarely seeps downward in desert soils, because plants take in most of the water after rare rainstorms.
EndFragment
Fallout from biomass – small In some deserts, plants have thorns to protect from animals. Fallout is larger where the plants grow rapidly, make seed, and die.
EndFragment
Decay from litter – medium/large. Micro-organisms work slowly where the soil is really dry, but hungry animals can eat dead leaves quickly.
EndFragment
Input from rocks – small. Chemical processes go very slowly in places with short rainy seasons that do not bring much water.
EndFragment
Loss in runoff – small. Rain is rare in a desert, but when storms do occur the intense rain can sometimes cause flash floods.
EndFragment
Input from rain – very small. Every raindrop condenses around a tiny bit of dust or salt. Input from rain is small in places that do not get much rain!
EndFragment
Loss in runoff – medium. Storms often bring rain faster than the ground can absorb it during the rainy summer, BUT runoff stops during the dry season.
EndFragment
Input from rain – medium. Every raindrop condenses around a tiny bit of dust or salt. Rain brings nutrients in only during a few summer months.
EndFragment
Uptake from soil – medium.Plants can grow rapidly in the summer rainy season, but they usually stop growing during the long dry season.
EndFragment
Loss by leaching – small/ medium. Water seeps down through the soil only when the soil is full of water in the last few months of the rainy season.
EndFragment
Fallout from biomass – medium. Some plants lose their leaves after the rainy season ends. Others are burned in fires that happen in the dry season.
EndFragment
Decay from litter – medium. Worms and soil micro-organisms can eat leaves and dead animals only during the rainy season.
EndFragment
Input from rocks – medium. Chemical processes go fast during the hot and rainy summer, but much slower in the dry “winter.”
EndFragment
Decay from litter – large.
Soil micro-organisms can consume
dead leaves, branches, or animals
quickly in a hot and rainy climate.EndFragment
Loss in runoff – large.
Equatorial storms often bring rain
faster than the soil can absorb it. When water flows off the land,
it takes nutrients with it.EndFragment
Loss by leaching – large.
Rainforests have plenty of water
- seeping down through the soil,
- dissolving nutrients, and
- carrying them away.EndFragment
Input from rain – large.
Every raindrop condenses
around a tiny bit of dust or salt. Storms bring plenty of nutrients into this ecosystem every month.EndFragment
Input from rocks – large.
Chemical processes go rapidly
where temperatures are high
and there is plenty of water.EndFragment
Fallout from biomass – small/medium.
This area has no cold or dry season
to make all the leaves change color
and fall down to the ground.EndFragment
Uptake from soil – very large.
Plants can grow rapidly
where temperatures are high
and rain falls in every month.
.EndFragment
Graphically Representing
the Nutrient Cycle
This is the kind of diagram that often appears in textbooks.
It identifies three general areas where nutrients can be “stored” in an ecosystem
- the soil (all the loose material that can be reached by plant roots)
- the biomass (living plants and animals), and
- the litter (fallen leaves, branches, dead animals, and other recently dead
or partly decayed organic matter).
These storage areas might be called boxes, compartments, residence areas,
or other names, depending on who wrote the textbook.
The storage areas are connected by a number of flows
(shown by arrows, and also called pathways, transfers, movements, or links).
This kind of diagram is useful as background, but it misses an important point:
The amounts in each box and the volume of each flow are different
in different parts of the world. Climate – temperature and precipitation – is the main cause for these differences.
The next page will have an interactive world map.
Click on any of the eight biomes to see what the nutrient cycle looks like there.
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