Productivity in Two Different Biomes
THE OLDEST AND MOST COMPLEX LAND-BASED ECOSYSTEM ON OUR PLANET – THE TROPICAL RAINFOREST
Tropical Rainforests are known for their complexity of interrelationships between plants and animals. Only about 1% of the light that is received at the uppermost canopy reaches the ground. Nearly all plants depend on sunlight for energy requirements as sunlight is converted into chemical energy in the form of carbohydrates through the process of photosynthesis. The ground level is therefore primarily composed of decomposing plant matter rather than living plants. Plants with similar structures belong to a specific synusia; the synusiae of a Tropical Rainforest include mechanically independent forms, which contain a supportive stem structure, saprophytes, which are plants, fungi, or microorganisms that live on dead or decomposing matter, and mechanically dependent species such as climbers and stranglers. The various-sized trees form canopies. The only chance for saplings to grow into maturity is the removal of overhanging vegetation or death or damage by wind to larger trees.
Tropical Rainforests support the greatest number of species compared to any other biome on the planet. The high species diversity is brought about by warm temperatures and year-round rainfall – the average yearly rainfall is 100 inches – that ultimately allow for optimal growth. The high number of plant species can thus support a high number of animal species. The warm, wet conditions result in rapid decomposition and any nutrients that are present within the soil are used by the quickly growing plants, causing the soil to be left poor in nutrient content. Nutrients, however, continue to cycle through the ecosystem as long as no damage is inflicted.
Gross Primary Productivity (GPP) is the total amount of organic matter synthesized by producers per unit area in unit time. Gross Primary Productivity refers to the total productivity including the energy that will ultimately be used for respiration, which is a chemical process in which energy is released from food substances such as glucose. Net Primary Productivity (NPP) is the total amount of energy converted from solar energy to chemical energy with the subtraction of the energy used for respiration. Net Primary Productivity is affected by temperature, water availability, carbon dioxide, and nutrients, all of which are abiotic factors. In Tropical Rainforests, water, sunlight, and high temperatures are consistent and a dense concentration of plants is present, causing both the GPP and NPP to be very high. So, high levels of productivity increase biomass.
WHAT COVERS NEARLY 20% OF OUR PLANET’S SURFACE AREA? THAT’S RIGHT! DESERTS DO!
“Kamel” (CC BY-NC-SA 2.0) by Astrid Kopp
A desert is often defined as any large, extremely dry area containing sparse vegetation that receives less than ten inches of average annual rainfall. Trees are few in number and the herbaceous plants that are present provide little ground cover. In some cases, extreme aridity causes deserts to be nearly completely devoid of plants. The low humidity, few bodies of water, and little vegetation absorb nearly all of the sunlight, heating the air at the soil’s surface. As the sun sets, however, nearly all of the heat present above and within the soil is released into the atmosphere, lowering the temperature drastically.
Many desert species have adapted behavioural techniques to avoid extreme heat. Many, particularly mammals and reptiles, are crepuscular – they are only active at dusk and dawn. Others are nocturnal, seeking protection under the surface of the soil or sand, often blocking their burrows to prevent the entrance of hot air. The Round-Tailed Ground Squirrel, for example, is a diurnal mammal that hibernates during the hottest portions of the summer as well as during winter. In regards to the dissipation of heat, bird species often gape open-mouthed while quickly moving the throat region to evaporate water from mouth cavities while dark-colored vultures urinate on their legs to cool by evaporation. Other organisms have large ears or have pale feathers, fur, scales, or skin. Desert plants conserve water through deep and shallow-spreading roots, a reduced number of stomata, rolled leaves, waxy leaf cuticles, succulent tissue, and spines. The stomata are often open at night – reversed stomatal rhythm.
Gross Primary Productivity and Net Primary Productivity are typically very low. Increases in productivity depend on nutrient distribution and the presence of moisture, which naturally allows for vegetation to grow before extreme arid conditions resume. The most fertile soil is often located beneath ground cover as shrub roots absorb nutrients and deposit them as plant litter on the surface, allowing for decomposition. The litter that is blown by the wind also allows for patchy, fertile areas to develop and thus increase productivity. So, depending on the amount of rainfall and nutrient distribution within a desert, certain areas may cause a larger GPP and NPP than others. Overall, the productivity of deserts is the lowest of all the biomes.
Questions for Readers:
(1) How does a Tropical Rainforest differentiate from a Desert? In your response, include your knowledge of the structure of these biomes and the organisms (with reference to their adaptations) that inhabit them.)
(2) What are the proper definitions of Gross Primary Productivity and Net Primary Productivity? Why are these indicators important?
(3) Why do Tropical Rainforests and Deserts have the productivity levels they do?
(4) Can human influences – positive or negative – impact productivity within any biome? Provide your opinion with justification using real-world examples.
CITATIONS
- All the Biomes. Digital image. Wikipedia – The Free Encyclopedia. Wikimedia Foundation, Inc., n.d. Web. 03 Nov. 2016. <https://upload.wikimedia.org/wikipedia/commons/thumb/e/e4/Vegetation.png/1280px-Vegetation.png>.
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Anderson, Joshua. “Biomes: Desert, Tropical Rainforest, Savanna, Coral Reefs & More.” Study.com. N.p., n.d. Web. 01 Nov. 2016. <http://study.com/academy/lesson/biomes-desert-tropical-rainforest-savanna-coral-reefs-more.html>.
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Average Temperature of Biomes. Digital image. The Desert Biome(s). N.p., n.d. Web. 03 Nov. 2016. <http://w3.marietta.edu/~biol/biomes/images/woodland/whittaker_v2.jpg>.
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“Desert Animal Survival.” DesertUSA. N.p., n.d. Web. 03 Nov. 2016. <http://www.desertusa.com/survive.html>.
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Haneef, Deena T Kochunni Jazir. “Difference between Gross Primary Productivity and Net Primary Productivity.” Major Differences. N.p., n.d. Web. 01 Nov. 2016. <http://www.majordifferences.com/2013/02/difference-between-gross-primary.html#.WBhKEOErJE4>.
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“Productivity.” Rainforest Conservation Fund. N.p., n.d. Web. 01 Nov. 2016. <http://www.rainforestconservation.org/rainforest-primer/rainforest-primer-table-of-contents/g-rainforest-ecology/4-productivity/>.
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“Rainforest Animals List – Information, Facts, & Pictures.” Active Wild. N.p., 04 Oct. 2016. Web. 01 Nov. 2016. <http://www.activewild.com/rainforest-animals-list/>.
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Smith, Jeremy. “Population and Community Development and Structure.” Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 03 Nov. 2016. <https://www.britannica.com/science/desert/Population-and-community-development-and-structure#ref589178>.
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Smith, Jeremy. “Tropical Rainforest – Population and Community Development and Structure.” Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 01 Nov. 2016. <https://www.britannica.com/science/tropical-rainforest/Population-and-community-development-and-structure#ref588852>.
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“Tropical Rainforest Plants List, Information, Pictures, & Facts.” Active Wild. N.p., 03 Dec. 2015. Web. 01 Nov. 2016. <http://www.activewild.com/tropical-rainforest-plants-list/>.
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“What Is a Desert?” DesertUSA. N.p., n.d. Web. 03 Nov. 2016. <http://www.desertusa.com/desert.html>.
Another key biome are the “Grasslands”
Location: north of the Tropic of Cancer and south of the Tropic of Capricorn
major grasslands include the veldts of Africa, pampas of South America, steppes of Euroasia and the plains of North America
Description: Include large rolling terrains of grass, herbs and flowers. Can support few trees and sustain grasses all year round.
Temperature: Hot summers and cold winters. Typically over 37°C in Summer and as cold as -40°C in the Winter
Precipitation: Between 25cm and 89cm of annual rainfall. The amount of precipitation determines the height of the grass, more rainfall results in higher grasses.
Example:
Hydrothermal vents:
What is a hydrothermal vent?
A hydrothermal vent forms a location where seawater meets magma. These venting black smokers emit small particles that are created when the heat of the magma meets the cold water. These particles are known as sulfide minerals. Hydrothermal fluid temperatures can reach 400°C. They are basically like hot springs on the ocean floors.
Hydrothermal vents are mostly found next to spreading ridges and convergent plates boundaries and therefore are underwater volcanoes.
example: Galapagos islands
ecosystem:
primary producer: chemosynthetic bacteria
primary consumer: crabs, worms, snails, and tube worms
secondary consumer: squid and octopuses
sources:
“Hydrothermal Vent Microbial Ecosystems – Boundless Open Textbook.” Boundless. N.p., n.d. Web. 07 Dec. 2016.
Society, National Geographic. “Deep Sea Hydrothermal Vents.” National Geographic Society. N.p., 2013. Web. 07 Dec. 2016.
Tropical Coral Reef:
Located between 30°north and south of the Equator where the water temperature never gets below 16°c
Primary producers: phytoplankton
Primary consumers: Parrotfish
secondary consumers: Barracuda
The Temperate Deciduous Forest
The forest has a specific temperature, annual precipitation and biodiversity. The biome is commonly characterised by a mixture of broad-leaf deciduous, and coniferous trees, along with with deer, and other fauna.
Annually, the temperate deciduous forest receives 750 to 1,500 mm of rain per year. This is due to the mid level latitude, allowing for the presence of rain while not in overwhelming quantities. This position in the globe also is a cause for the temperature, which ranges from -30°C to 30° on average with a yearly average of 10°C. These factors together make it possible for the specific flora to thrive there. It is seen in the United states, China, Japan, Canada, Europe, and a select portion of Australia.
The range of the biome is what helps for there to be such a large range of species diversity. There are many examples of different species for every tier or level in the ecosystem. In the first level, the producers, there are Maple trees for example. They are very common and loose there leaves in the winter. A second tier or primary consumer could be a cottontail rabbit. They burrow around and mostly eat wild grasses and berries, aka producers. A third tier animal would be a red fox, as it would eat prey on the rabbits and consume them for energy. After that would be a few possibilities for the final tier, such as a coyote. The coyote would prey on both the fox and the rabbit and therefore be the final tier level because no other species would predate upon it.
Tundras are among Earth’s coldest, harshest biomes. Tundra ecosystems are treeless regions found in the Arctic and on the tops of mountains, where the climate is cold and windy and rainfall is scant. Tundra lands are snow-covered for much of the year, until summer brings a burst of wildflowers. Mountain goats, sheep, marmots, and birds live in mountain, or alpine, tundra and feed on the low-lying plants and insects. Hardy flora like cushion plants survive on these mountain plains by growing in rock depressions where it is warmer and they are sheltered from the wind.