Ecology

Wildlife

Among the small number of bird (e.g., ptarmigan) and mammal (e.g.,arctic hare, arctic fox, musk ox) species that reside year-round on the tundra one commonly finds: Morphological adaptations: large, compact bodies; a thick insulating cover of feathers or fur; pelage and plumage that turns white in winter and brown in the summer. Physiological adaptations: ability to accumulate thick deposits of fat during the short growing season. Fat acts as insulation and as a store of energy for use during the winter, when animal species remain active. Population adaptations: cyclical fluctuations in population size; best seen perhaps in the lemming, a small rodent which is the major herbivore in the tundra's simple food chain. Predator populations and plant populations respond in kind to the peaks and crashes of the herbivore populations.

Mutualism

An association between organisms of two different species in which each member benefits. Some examples include: 1. tick bird and rhino 2. legumes and nitrogen fixing bacteria 3. E. coli and humans

Organism

An individual form of life, such as a plant, animal, bacterium, protist, or fungus; a body made up of organs, organelles, or other parts that work together to carry on the various processes of life.

Two Patterns of Population Growth

1. logistic 2. exponential

Community

A group of plants and animals living and interacting with one another in a specific region under relatively similar environmental conditions. The region occupied by a group of interacting organisms. It is a biotic community meaning living organisms only.

Commensalism

A symbiotic relationship between two organisms of different species in which one derives some benefit while the other is unaffected. Example: barnacle and whale

Predator/Prey Relationship

All animals must eat to survive. With predators always on the lookout for a meal, prey must constantly avoid being eaten. Any adaptation the prey uses adds to its chances of survival for the species. Some adaptations are defense mechanisms which can give the prey an advantage against enemies.

Population

All the organisms that constitute a specific group, found in a specified habitat, and that can interbreed.

Biomes

Biomes can be classified into one of 5 categories categories: Tundra, Taiga, Tropical Rain Forest, Desert, Deciduous/Temperate Forests.

Ecological Succession

Changes occur because each community that establishes itself changes the environment, making it more unfavorable for itself and more favorable for the community that is to succeed it.

Producers

autotrophs/ primary trophic level with the greatest biomass. At this level the plants absorb sunlight and convert it to chemical energy (glucose) via photosynthesis.

Carnivores

feed on herbivores and other heterotrophic organisms

Hervibores

feed on primary producers that utilize the sun for energy

Secondary Consumers

heterotrophs/ carnivores. This is the third trophic level with the smallest amount of biomass. Similar to primary consumers only a small amount of energy is transferred (energy loss) tertiary consumer - birds final consumer - hawk

Primary Consumers

heterotrophs/ herbivores. This is the second trophic level with less biomass than the last level. Primary consumers eat plants and derive energy from glucose. However these consumers have large energy losses from metabolism. Only a small amount of energy is transferred to the next level.

The biosphere

is the part of the Earth and its atmosphere in which living organisms have the potential to exist. The biosphere is comprised of the living organisms and their surrounding environment. In other words, the biosphere may be thought of as a conglomeration of all the portions of the planet that support life: the atmosphere, the lithosphere, and the hydrosphere.

Exponential

no limiting factors; characteristic of bacteria in a lab provided with all nutrients and ample space to grow; typically not the growth pattern followed in nature.

Primary Producers

obtain their energy from the sun or chemical sources and utilize inorganic compounds from the environment to make organic compounds.1

Sunlight:

primary source of energy

Detrivores

scavengers (ex. Vultures) / decomposers (ex fungi and bacteria). This group lives on dead organic matter. They consume organic matter derived from many trophic levels.

logistic

sigmoidal (S shaped) curve; occurs more often in nature; K = carrying capacity, the environment can only support a certain number of living things because of limited resources (water, food)

Omnivores

this group eats both plants and animals

Desert

Desert areas are rarely devoid of life. Instead, they abound with wonderfully adapted plants and animals that have evolved various mechanisms for tolerating or avoiding the extremes of aridity and temperature that might be encountered in their environment. Climate. The desert is typified by arid climates that average less than 10 inches of precipitation a year. Potential evaporation exceeds precipitation in the annual water budget. Furthermore, rainfall is highly localized and relatively unpredictable in terms of when it will occur, although usually there are seasons of highest probability for precipitation. Annual variation in total precipitation may also be great. Temperatures are also variable. They may exceed 100° F on summer afternoons, but dip by 20-30 degrees or more at night. Winters are cool to cold: "hot deserts" rarely experience frost; "cold deserts" may have prolonged periods of below freezing temperatures and snowfall. Vegetation. Shrubs are the dominant growthform of deserts. They may be evergreen or deciduous; typically have small leaves; and frequently have spines or thorns and/or aromatic oils. Shallow but extensive root systems procure rainwater from well beyond the canopy of the shrub whenever it does rain. Water is not entirely lacking in the desert environment and several other growthforms represent strategies to reach water or to store water.

Deciduous Temperate Forests

Found especially in eastern North America and is known for the turning of the colors of its leaves to brilliant reds, oranges, and golds in autumn. The shortening days of fall stimulate the plants to withdraw chlorophyll from their leaves, allowing a brief but beautiful display of other pigments before the leaves are shed completely and plants enter an extended period of dormancy. Climate: Associated with warmer continental and humid subtropical climates. There is an approximately 6 month growing season. The 20 to 60 inches of precipitation is distributed evenly throughout the year. The non-growing season is due to temperature-induced drought during the cold winters. Vegetation: Many of the same genera. Included among these genera are Quercus (oak), Acer (maple), Fagus (beech), Castanea (chestnut), Carya (hickory), Ulmus (elm), Tilia (basswood or linden), Juglans (walnut), and Liquidamber (sweet gum). Different species of these genera occur on each continent. Wildlife: Either mast-eaters (nut and acorn feeders) or omnivores. Mammals show adaptations to an arboreal life; a few hibernate during the winter months. North American herbivores include white-tail deer, gray squirrel, and chipmunk. Omnivores include raccoon, opossum, skunk, and black bear. Carnivores have been largely eliminated through the deliberate effort of humans but should include timber wolves, mountain lions, and bobcats. The coyote, native to the western grasslands and deserts, has recently dispersed east and taken over the niche of its departed cousin, the timber wolf. Resident bird species also tend to be seed-eaters or omnivores.

Energy levels

In a food chain, energy moves in a linear fashion from producers through consumers. Energy is captured by primary producers and transferred to higher trophic levels. At each transfer, only a fraction of the energy is passed on and much is lost. These losses appear in the form of heat and in inefficiencies in processing and assimilating energy. Thus, the total available energy declines as one moves up trophic levels in a food chain. This places a limit on the number of trophic levels that can exist. At some point, there is too little energy available to sustain further transfers.

Ecosystem

Involves the interaction of living (biotic) communities and the non-living (abiotic) factors in their environment (biomes).

Parasitism

The relationship between two organisms in which one organism benefits from the other at the other's expense. The damage incurred by the other organism, however, is usually not fatal. Example: tapeworm and human

Carbon Facts

Life on Earth is carbon-based. Carbon is a lively element that readily combines with other elements to make organic compounds. A relatively large percentage of our body is made up of carbon. Some of the carbon in your body was a part of living plants only a few months ago. Through photosynthesis, plants make carbohydrates (chemical compounds made of carbon, oxygen and hydrogen) that animals then eat for food. Humans can accumulate carbon from plants directly or indirectly by eating plants or the animals that consumed plants. Some components of the carbon cycle are very fast; however, the rock-forming part and the coal-petroleum-natural gas part take millions of years. Sediments are the largest reservoirs of carbon in the ocean; however, this source of carbon is not accessible to life. On land, forests are the largest reservoirs of carbon, comprising up to 80% of the aboveground carbon. Most of it is in the tissues of trees. Russia and the Amazon basin together hold about 45% of the world's forest carbon. Living organisms are crucial to the carbon cycle.

Nitrogen Facts

Nitrogen is one of the most abundant elements on Earth. 79% of Earth's atmosphere is nitrogen in gas form. No living cell can exist without nitrogen. But, organisms cannot use nitrogen in gas form. Multicellular life (plants, animals and fungi) depend almost entirely on bacteria to obtain (or "fix") nitrogen from the air and transform it into a chemical form that plants can use. -Some of these talented bacteria live symbiotically with legumes such as beans, which take nitrogen out of the air in soils. -Other bacteria live freely in the soil, processing manures and urine, and also helping to decompose dead plants and animals. -A third kind of bacteria lives in the soil and changes "fixed" nitrogen (a hydrogen compound) into nitrates (oxygen compounds), which plants can use. Without these nitrifying bacteria, agricultural fertilizers do not work. In the ocean, cyanobacteria fix nitrogen for marine life. Plants assimilate nitrogen from soil, and with it create amino acids and proteins. Animals get nitrogen from eating plants or from eating other animals.

Primary vs. Secondary Succession

Primary succession: occurs where no previous organisms existed. An example would be a new island that formed as a result of volcanic activity. Secondary succession: occurs where the existing community is removed (e.g. fire).

Desert Wildlife

Reptiles with their waterproof skin, production of uric acid instead of urine, hard-shelled eggs, and ability to gain body heat directly from the sun and to retreat to shade or underground to avoid heat are exceptionally well adapted to drylands. Most animals are nocturnal when the temperature is lower.

Nitrogen Paths

The Nitrogen Cycle has two major beginnings and two major paths Nitrogen from air ---> soil nitrogen-fixing bacteria ----> nitrifying bacteria ----> plants ----->animals -----> decomposers Nitrogen from dead organisms ---> decomposers ----> nitrifying bacteria ----> plants You should also know that a little nitrogen is fixed by lightning, and that volcanoes release some nitrates: both are carried to soils by rain.

niche

The function and position of an organism/population within an ecological community. It includes where the organism/population lives, its diet, its food sources, its climatic factors and its reproductive method Organisms occupying the same niche will compete for limited resources and may result in displacement or extinction of one species.

Succession

The gradual and orderly process of ecosystem development brought about by changes in community composition and the production of a climax characteristic of a particular geographic region is known as succession.

Taiga

The taiga or boreal forest exists as a nearly continuous belt of coniferous trees across North America and Eurasia. Overlying formerly glaciated areas and areas of patchy permafrost on both continents, the forest is mosaic of successional and subclimax plant communities sensitive to varying environmental conditions. Taiga is the Russian name for this forest which covers so much of that country. However, the term is used in North America as well. Climate: The taiga corresponds with regions of subarctic and cold continental climate (Koeppen's Dfc, Dfd, and Dwd climate types). Long, severe winters (up to six months with mean temperatures below freezing) and short summers (50 to 100 frost-free days) are characteristic, as is a wide range of temperatures between the lows of winter and highs of summer. For example, Verkhoyansk, Russia, has recorded extremes of minus 90 ° F and plus 90 ° F. Mean annual precipitation is 15 to 20 inches, but low evaporation rates make this a humid climate. Vegetation: Needleleaf, coniferous (gymnosperm) trees are the dominant plants of the taiga biome. A very few species in four main genera are found: the evergreen spruce (Picea), fir (Abies), and pine (Pinus), and the deciduous larch or tamarack (Larix). In North America, one or two species of fir and one or two species of spruce are dominant. Across Scandanavia and western Russia the Scots pine is a common component of the taiga. Broadleaf deciduous trees and shrubs are members of early successional stages of both primary and secondary succession. Most common are alder (Alnus), birch (Betula), and aspen (Populus). Growthforms: The conical or spire-shaped needleleaf trees common to the taiga are adapted to the cold and the physiological drought of winter and to the short-growing season: Conical shape - promotes shedding of snow and prevents loss of branches. Needleleaf - narrowness reduces surface area through which water may be lost (transpired), especially during winter when the frozen ground prevents plants from replenishing their water supply. Evergreen habit - retention of foliage allows plants to photosynthesize as soon as temperatures permit in spring, rather than having to waste time in the short growing season merely growing leaves. Dark color - the dark green of spruce and fir needles helps the foliage absorb maximum heat from the sun and begin photosynthesis as early as possible.

Tropical Rain Forest

The tropical rainforest is earth's most complex biome in terms of both structure and species diversity. It occurs under optimal growing conditions: abundant precipitation and year round warmth. There is no annual rhythm to the forest; rather each species has evolved its own flowering and fruiting seasons. Sunlight is a major limiting factor. A variety of strategies have been successful in the struggle to reach light or to adapt to the low intensity of light beneath the canopy. Climate: Mean monthly temperatures are above 64 ° F; precipitation is often in excess of 100 inches a year. There is usually a brief season of reduced precipitation. In monsoonal areas, there is a real dry season, but that is more than compensated for with abundant precipitation the rest of the year. Wildlife: Great variety of plants and animal. Tropical species of trees frequently possess one or more of the following attributes not seen in trees of higher latitudes. Buttresses: many species have broad, woody flanges at the base of the trunk. Originally, it was believed that their role was to support the tree; now, it is believed that the buttresses channel the stem flow and its dissolved nutrients to the roots. Large leaves: The large leaf surface helps intercept light in the sun-dappled lower strata of the forest. Drip tips facilitate drainage of precipitation off the leaf to promote transpiration.

Distribution

The tundra biome is restricted to the high latitudes of the northern hemisphere in a belt around the Arctic Ocean. Many of its species, both plant and animal, have circumpolar distribution areas.

The Food Chain

Trophic levels are a way of identifying what kinds of food an organism uses. In food chains, the total number of trophic levels depends upon the location and number of different species. In general, the highest trophic level is occupied by adult animals with no predators of their own. For example, killer whales would occupy the highest trophic level in an antarctic food chain.

Tundra

Vegetation: lichens, mosses, sedges, perennial forbs, and dwarfed shrubs, (often heaths, but also birches and willows). Growthforms: typical are ground-hugging and other warmth-preserving forms including: rosettes and dwarf shrubs. Climate: extremely short growing season (6 to 10 weeks). long, cold, dark winters (6 to 10 months with mean monthly temperatures below 32° F or 0° C). low precipitation (less than five inches/year) coupled with strong, drying winds. Snowfall is actually advantageous to plant and animal life as it provides an insulating layer on the ground surface.