Chapter 4 Managing ecosystems and biodiversity Flashcards
The world’s ecosystems are essential for the survival and well-being of people everywhere in the world. The emphasis in this section is on understanding the energy transfers that sustain the biodiversity of the world’s ecosystems and how we can best manage these ecosystems to conserve that biodiversity. (19 cards)
** Terrestial biomes**
A terrestrial biome is a land region on the earth’s surface covered by biological communities that group under the same climatic patterns like rainfall and temperature. Temperature and precipitation or rainfall are the main driving factors determining the terrestrial biome type. These biomes are land regions with their ecosystems dependent on common climatic patterns
World’s Major Terrestial biomes in terms of climate, soil type and vegatation
Terrestrial biomes are forests, grassland, desert, and tundra.
Forest
- three types of tree ecosystems: tropical, temperate, and taiga or boreal forests.
- When warm and wet, tropical forests are called rainforests, while dry and cool conditions result in deciduous forests.
- characterized by thick canopy and tall or short trees.
- Temperate forests are found in regions that have mid-range temperatures and all four seasons.
- Taiga or boreal forests are the ones that have cold, dry winters and short, cool, wet summers.
Grassland
- Grasslands are land regions that do not have trees but only grass vegetation.It is of two types: temperate and tropical.
- Tropical Savannas are characterized by hot temperatures with tall grass and scattered short trees. They have limited rainfall or precipitation.
- Temperate grasslands have shorter grass. They are also classified as pampas, steppe, prairie, and savanna.
Desert Biomes
- They are dry regions that hardly have any vegetation, and if there is, they are adapted specially to suit the dry climate with the least rainfall to access water for survival.
- The deserts have hot days and cold nights with extreme summers and winters.
- There are three types of deserts – hot, cold, and coastal deserts.
Tundra
- Tundra is a polar desert and is entirely covered with snow throughout the year, with the depth of snow forming as a part of the layer of soil called permafrost.
- The vegetation is seen as short herbs to shrubs or grass only during the summer.
- Tundra regions are found only in the earth’s polar regions and are cold year-round.
- Alpine and arctic tundra are the two common types of tundra regions
Define Succession, Primary and Secondary succession, Climax Community
- Succession is a series of progressive changes in the composition of an ecological community over time.
- In primary succession, newly exposed or newly formed rock is colonized by living things for the first time.
- In secondary succession, an area previously occupied by living things is disturbed—disrupted—then recolonized following the disturbance.
- Climax community: A stable community in its final stage of ecological succession.
Characteristics of primary and secondary succession from pioneer species through intermediate states to a climax community
Relative timeline: Represents a timeline of life on earth from the origin of the earth. The geological timescale divides the earth’s history into three main eras i.e. Paleozoic, Mesozoic and Coenozoic eras which are divided into periods.
Starting Point
Soil Pioneer species - group of species that are the first to colonize a new habitat created by a previous disturbancewhich include lichens, mosses, fungi, and microorganisms such as bacteria—reproduce and grow quickly, enabling them to take advantage of the resources in a barren environment before larger competitors arrive
Gross Primary Productivity
- Gross primary productivity is the amount of carbon fixed during photosynthesis by all producers in the ecosystem.
- Producers such as plants use some of this energy for metabolism/cellular respiration and some for growth (building tissues)
Net Primary Productivity
- Net primary productivity, or NPP, is gross primary productivity minus the rate of energy loss to metabolism and maintenance.
- it is the rate at which energy is stored as biomass by plants or other primary producers and made available to the consumers in the ecosystem
Ecosystem Productivity
- The rate of production of biomass for an ecosystem
* - Productivity can be defined for any trophic level or other group, and it may take units of either energy or biomass. There are two basic types of productivity: gross and net.
Efficiency of Energy Transfer between trophic levels
- Energy can pass from one trophic level to the next when organic molecules from an organism’s body are eaten by another organism.
- The transfer of energy between trophic levels is not usually very efficient. On average, only about 10% of the energy stored as biomass in one trophic level (e.g., primary producers) gets stored as biomass in the next trophic level (e.g., primary consumers).
- net productivity usually drops by a factor of ten from one trophic level to the next
Why is energy transfer inefficient?
- Not all the organisms at a lower trophic level get eaten by those at a higher trophic level.
- Some molecules in the bodies of organisms that do get eaten are not digestible by predators and are lost in the predators’ feces (poop). The dead organisms and feces become dinner for decomposers.
- The energy-carrying molecules that do get absorbed by predators, some are used in cellular respiration (instead of being stored as biomass).
Ecological Pyramids (3 Types)
Numbers, Biomas and Energy
Energy Pyramids
- Energy pyramids represent energy flow through trophic levels. An energy pyramid usually shows rates of energy flow through trophic levels, not absolute amounts of energy stored. It can have energy units, such as kcal/m2/yrkcal/m2/yrstart text, k, c, a, l, slash, m, end text, squared, start text, slash, y, r, end text, or biomass units, such as g/m2/yrg/m2/yrstart text, g, slash, m, end text, squared, start text, slash, y, r, end text..
- Energy pyramids are always upright, that is, narrower at each successive level (unless organisms enter the ecosystem from elsewhere). This pattern reflects the laws of thermodynamics, which tell us that new energy can’t be created, and that some must be converted to a not-useful form (heat) in each transfer.
Biomass Pyramids
These pyramids represent the amount of energy that’s stored in living tissue at the different trophic levels. (Unlike energy pyramids, biomass pyramids show how much biomass is present in a level, not the rate at which it’s added.)
Numbers pyramids
Numbers pyramids show how many individual organisms there are in each trophic level. They can be upright, inverted, or kind of lumpy, depending on the ecosystem.
Key points on Energy Transfer
- Primary producers, which are usually plants and other photosynthesizers, are the gateway through which energy enters food webs.
Productivity is the rate at which energy is added to the bodies of a group of organisms, such as primary producers, in the form of biomass. Gross productivity is the overall rate of energy capture. Net productivity is lower: it’s gross productivity adjusted for the energy used by the organisms in respiration/metabolism, so it reflects the amount of energy stored as biomass. - Energy transfer between trophic levels is not very efficient. Only 10% of the net productivity of one level ends up as net productivity at the next level.
- Ecological pyramids are visual representations of energy flow, biomass accumulation, and number of individuals at different trophic levels.
Native Species and Invasive Speciaes
- Native: a species that originated and developed in its surrounding habitat and has adapted to living in that particular environment.
- **Invasive: **is an organism that is not indigenous, or native, to a particular area. Invasive species can cause great economic and environmental harm
