Ecology - Terrestrial Ecosystems

Science Olympiad Division C

Desertification

Desertification is the process in which a region becomes arid. It is primarily driven by climate change in the modern world; Conversion of rangeland, rain-fed cropland, or irrigated cropland to desert-like land, with a drop of agricultural productivity of 10% or more

The importance of plants

Without soil and plants the land becomes desert-like and unable to support life; this process is called desertification. It is very difficult- often impossible, in fact-to restore desertified land

Desert

Biome in which evaporation exceeds precipitation and the average amount of precipitation is less than 25 centimeters a year. Such areas have little vegetation or have widely spaced, mostly low vegetation

Biodiversity

Variety of different species (species diversity), genetic variability among individuals within a species (genetic diversity), variety of ecosystems (ecological diversity), and functions such as energy flow and matter cycling needed for the survival of a species and biological communities

Types of biodiversity

Genetic Biodiversity, Species Biodiversity, and Ecological Biodiversity

Genetic Biodiversity

the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species.

Species Biodiversity

the number of different species that are represented in a given community. The effective number of species refers to the number of equally abundant species needed to obtain the same mean proportional species abundance as that observed in the dataset of interest.

Ecological Biodiversity

the diversity of ecosystems, natural communities, and habitats. In essence, it's the variety of ways that species interact with each other and their environment.

Selection

In the context of evolution, certain traits or alleles of a species may be subject to selection. Under selection, individuals with advantageous or "adaptive" traits tend to be more successful than their peers reproductively--meaning they contribute more offspring to the succeeding generation than others do

Natural selection

The differential survival and reproduction of organisms with genetic characteristics that enable them to better utilize environmental resources

Stabilizing selection

Stabilizing selection is a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait

Disruptive selection

Disruptive selection is a type of natural selection that simultaneously favors individuals at both extremes of the distribution. When disruptive selection operates, individuals at the extremes contribute more offspring than those in the center, producing two peaks in the distribution of a particular trait

Directional selection

In population genetics, directional selection occurs when natural selection favors a single allele and therefore allele frequency continuously shift in one direction

Artificial selection

The process in which breeders choose the variants to be used to produce succeeding generations

Grassland

Biome found in regions where moderate annual average precipitation (25-76 cm) is enough to support the growth of grass and small plants but not enough to support large stands of trees

Taiga biome importance

Filters millions of liters of water

It stores large amounts of carbon

Produces oxygen

It rebuilds soils and restores nutrients

Bogs and marshes provides habitats for large numbers of species from fish to birds

Differences between arctic tundra biome and alpine tundra biome

Because alpine tundra only exists on mountains, the soil is always very well drained, as opposed to the often soggy soil of arctic tundra.

Alpine tundra exists because of high altitude, this means that the biome can exist at many different altitudes, so long as there are mountains. This means that alpine tundra that is farther south may receive much more solar radiation than arctic tundra which leads to greater evaporation rates.

As global warming continues, the biomes are shifting. Organisms in arctic tundra can generally migrate north to find the conditions they are adapted to. However organisms that live in alpine tundra are trapped on 'islands' of suitable habitat. They are adapted to a tundra climate and can not effectively compete with organisms in habitats lower down on the mountains. This traps the organisms on their mountains and does not allow them to migrate to other mountains. As global warming progresses, these organisms are pushed higher up onto their mountains. In some cases, the mountains may not extend any higher, and organisms are pushed to local extinction.

Alpine tundra generally has a lower oxygen concentration due to the thinning of the atmosphere as you rise in altitude.

Deciduous forests biome importance

Reduce erosion from the trees stabilizing the soil, provide habitat and food for many animals including migratory birds from the Tundra. The forests aid in maintaining biodiversity, regulating local climate, and producing oxygen. This helps to stabilize weather patterns as well as diminish the effects of greenhouse gas release into the atmosphere. The trees regulate watershed volume to reduce water, while the no one serves as a large water and air filter. As a result, the forest indirectly regulates stream flow and temperature. It aids in nutrient cycling and soil formation and creates a healthier soil for the plants that live in it.