Transcript Biomes - geo-revision.net

Biomes
A distinct ecological community of plants and animals living together
in a particular climate is called a "biome.
The concept of an ecosystem
An ecosystem consists of the
biological community that occurs in
some locale, and the physical and
chemical factors that make up its
non-living or abiotic environment.
Ecosystems
Organisation within an ecosystem
population
community
habitat
niche
Population
Community
Habitat
Niche
A given animal or plant lives in a particular place, is active at
particular times and eats particular things, and these factors define
its ecological niche.
The environment is divided into millions of ecological niches, each of
which represents a potential 'home' for life. Animals and plants will
always try and take advantage of new opportunities, and so will
always attempt to make a 'home' in an empty niche.
In general, only one animal or plant can occupy a particular
ecological niche - when two organisms try to occupy the same niche
they will compete for the same resources, and one will always outcompete the other. However, when a niche becomes vacant - for
example when the species which occupied it becomes extinct - there
is a race to try and fill it. Mass extinctions open up a multitude of
niches, and there is an evolutionary explosion as animals and plants
adapt to fill the vacant 'homes'.
As the Earth's environment changes over time some niches may be
destroyed, driving the species which occupied them to extinction they literally lose their ecological home.
Physical factors
temperature
humidity
water
salinity
light
pH
soils
nutrients
Wind
temperature
The whale is normally seen in the deep northern Atlantic. Scientists have
said fluctuating ocean temperatures, predators, lack of food and even
sonar from ships can send whales into waters that are dangerous for the
mammals
humidity
water
salinity
Concentration of dissolved salts found in a sample of water. Measured
as the total amount of dissolved salts in parts per thousand. Seawater
has an average salinity of about 34 parts per thousand (ppt).
light
pH
Scale used to measure the alkalinity or acidity of a substance
through the determination of the concentration of hydrogen ions
in solution. A pH of 7.0 is neutral. Values below 7.0, to a
minimum of 0.0, indicate increasing acidity. Values above 7.0, to
a maximum of 14.0, indicate increasing alkalinity. Soil pH (a
measure of the acidity or alkalinity of the soil)ﾊ ﾊ･Soil pH is one
of the most important soil properties that affects the availability
of nutrients.
Macronutrients tend to be less available in soils with low pH.
Micronutrients tend to be less available in soils with high pH.
Lime can be added to the soil to make it less sour (acid) and
also supplies calcium and magnesium for plants to use. Lime
also raises the pH to the desired range of 6.0 to 6.5. In this pH
range, nutrients are more readily available to plants, and
microbial populations in the soil increase. Microbes convert
nitrogen and sulfur to forms that plants can use. Lime also
enhances the physical properties of the soil that promote water
and air movement.
soils
Soil Texture (the amount of sand, silt, clay, and organic matter
in the soil).
Soil texture affects how well nutrients and water are retained in
the soil. Clays and organic soils hold nutrients and water much
better than sandy soils. As water drains from sandy soils, it often
carries nutrients along with it. This condition is called leaching.
When nutrients leach into the soil, they are not available for
plants to use. An ideal soil contains equivalent portions of sand,
silt, clay, and organic matter. Soils across North Carolina vary in
their texture and nutrient content, which makes some soils more
productive than others. Sometimes, the nutrients that plants
need occur naturally in the soil. Othertimes, they must be added
to the soil as lime or fertilizer.
nutrients
Non-Mineral Nutrients
The Non-Mineral Nutrients are hydrogen (H), oxygen (O), & carbon (C).
These nutrients are found in the air and water.
In a process called photosynthesis, plants use energy from the sun to change c
carbon dioxide (CO2 - carbon and oxygen) and water (H2O- hydrogen and
oxygen) into starches and sugars. These starches and sugars are the plant's
food.
Photosynthesis means "making things with light"
The 13 mineral nutrients, which come from the soil, are dissolved in water and absorbed
through a plant's roots. There are not always enough of these nutrients in the soil for a
plant to grow healthy. This is why many farmers and gardeners use fertilizers to add the
nutrients to the soil.
The mineral nutrients are divided into two groups:
macronutrients and micronutrients.
Macronutrients
Macronutrients can be broken into two more groups:
primary and secondary nutrients.
The primary nutrients are nitrogen (N), phosphorus (P), and potassium (K). These major
nutrients usually are lacking from the soil first because plants use large amounts for
their growth and survival.
The secondary nutrients are calcium (Ca), magnesium (Mg), and sulfur (S). There are
usually enough of these nutrients in the soil so fertilization is not always needed. Also,
large amounts of Calcium and Magnesium are added when lime is applied to acidic
soils. Sulfur is usually found in sufficient amounts from the slow decomposition of soil
organic matter, an important reason for not throwing out grass clippings and leaves.
Micronutrients
Micronutrients are those elements essential for plant growth which are needed in only
very small (micro) quantities . These elements are sometimes called minor elements or
trace elements, but use of the term micronutrient is encouraged by the American Society
of Agronomy and the Soil Science Society of America. The micronutrients are boron
(B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo) and zinc
(Zn). Recycling organic matter such as grass clippings and tree leaves is an excellent
way of providing micronutrients (as well as macronutrients) to growing plants.
wind
Relationships of living organisms








producers
consumers
food chains and webs
competition
predation
pollination
dispersal
vegetational succession
Producers
consumers
Consumers get their energy from the carbon bonds made by the producers. Another
word for a consumer is a heterotroph. Based on what they eat, we can distinguish
between 4 types of heterotrophs:
consumer
trophic level
food source
Herbivores
primary
plants
Carnivores
secondary or higher animals
Omnivores
all levels
Detritivores
---------------
plants & animals
detritus
competition
2 species compete for the same resource
if there is not enough to support both.
Examples: A Douglas Fir & Western
Hemlock grow together in the mixed
conifer forests of Oregon, competing for
minerals, water, and light. A scrub jay and
a gray squirrel compete for nuts and
seeds within the oak forest.
predation
A consumer feeds on another
consumer.
Examples: The cougar is a predator
of black-tailed deer. The great white
shark is a predator of harbor seals.
pollination
Pollination is an important step in the
reproduction of seed plants: the transfer of
pollen grains (male gametes) to the plant
carpel, the structure that contains the ovule
(female gamete).
dispersal
The movement of organisms from one
place to another is called dispersal.
Whirling Nut (Gyrocarpus)
Vegetational succession
SuccessionDirectional cumulative
change in the types plant species that
occupy a given area, through time.
Energy flows
photosynthesis
respiration
food chains
food webs
Energy Flow Through the Ecosystem
photosynthesis
respiration
Aerobic respiration is the release of energy from glucose or another organic
substrate in the presence of Oxygen. Strictly speaking aerobic means in air, but
it is the Oxygen in the air which is necessary for aerobic respiration. Anaerobic
respiration is in the absence of air.
Glucose + Oxygen = Carbon Dioxide + Water + Energy
Food chains
A food chain is the path of food from a given final consumer back to a producer. For
instance, a typical food chain in a field ecosystem might be:
grass ---> grasshopper --> mouse ---> snake ---> haw
Food webs
Nutrient cycling
carbon cycle
nitrogen cycle
carbon cycle
Nitrogen cycle
Biological Fixation
Legumes, a special group of plants, are able to make or "fix"
nitrogen. Special bacteria live on the roots of legumes. The bacteria
receive "food" in the form of carbohydrates from the plants. In return,
the bacteria use elemental nitrogen (N2) and change it to organic
forms of nitrogen that the plant can use.
Resource potential
biodiversity as a genetic resource
and as a food base
Biodiversity as a genetic resource
Wild varieties possess genetic
resistance to pests, therefore represent
a form of biological insurance.
Monocultures are susceptible to pest
attacks.
Many major drugs come from tropical
plants. Undiscovered drugs may be
found.
Biodiversity as food base
Plant species need to be maintained as
a potential source of food.