Therefore, soil structure the particle size of soil components , soil pH, and soil nutrient content play an important role in the distribution of plants.
Animals obtain inorganic nutrients from the food they consume. Therefore, animal distributions are related to the distribution of what they eat. In some cases, animals will follow their food resource as it moves through the environment. Jack pine cones : The mature cones of the jack pine Pinus banksiana open only when exposed to high temperatures, such as during a forest fire. A fire will probably kill most vegetation, so a seedling that germinates after a fire is more likely to receive ample sunlight than one that germinates under normal conditions.
Some abiotic factors, such as oxygen, are important in aquatic ecosystems as well as terrestrial environments. Terrestrial animals obtain oxygen from the air they breathe.
Oxygen availability can be an issue for organisms living at very high elevations, where there are fewer molecules of oxygen in the air. In aquatic systems, the concentration of dissolved oxygen is related to water temperature and the speed at which the water moves. Cold water has more dissolved oxygen than warmer water. In addition, salinity, water current, and tide can be important abiotic factors in aquatic ecosystems.
Wind can be an important abiotic factor because it influences the rate of evaporation and transpiration. Fire is another terrestrial factor that can be an important agent of disturbance in terrestrial ecosystems.
Some organisms are adapted to fire and, thus, require the high heat associated with fire to complete a part of their life cycle.
For example, the jack pine, a coniferous tree, requires heat from fire for its seed cones to open. Through the burning of pine needles, fire adds nitrogen to the soil and limits competition by destroying undergrowth.
The two most important abiotic factors affecting plant primary productivity in an ecosystem are temperature and moisture. Temperature and moisture are important influences on plant production primary productivity and the amount of organic matter available as food net primary productivity. Primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide.
It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through chemosynthesis, which uses the oxidation or reduction of chemical compounds as its source of energy. Almost all life on earth is directly or indirectly reliant on primary production. The organisms responsible for primary production, known as primary producers or autotrophs, form the base of the food chain.
In terrestrial eco-regions, these are mainly plants, while in aquatic eco-regions, they are mainly algae. Net primary productivity is an estimation of all of the organic matter available as food. It is calculated as the total amount of carbon fixed per year minus the amount that is oxidized during cellular respiration.
In terrestrial environments, net primary productivity is estimated by measuring the aboveground biomass per unit area, which is the total mass of living plants, excluding roots. This means that a large percentage of plant biomass which exists underground is not included in this measurement. Net primary productivity is an important variable when considering differences in biomes. Very productive biomes have a high level of aboveground biomass. Annual biomass production is directly related to the abiotic components of the environment.
Environments with the greatest amount of biomass have conditions in which photosynthesis, plant growth, and the resulting net primary productivity are optimized.
The climate of these areas is warm and wet. Photosynthesis can proceed at a high rate, enzymes can work most efficiently, and stomata can remain open without the risk of excessive transpiration.
Together, these factors lead to the maximal amount of carbon dioxide CO 2 moving into the plant, resulting in high biomass production. The aboveground biomass produces several important resources for other living things, including habitat and food. Conversely, dry and cold environments have lower photosynthetic rates and, therefore, less biomass. The animal communities living there will also be affected by the decrease in available food. Primary productivity and biomass production : The magnitude and distribution of global primary production varies between biomes.
However, warm and wet climates have the greatest amount of annual biomass production. Privacy Policy. Skip to main content. Ecology and the Biosphere. Search for:. Biogeography Biogeography is an ecological field of interest that focuses on the distribution of organisms and the abiotic factors that affect them. Learning Objectives Explain the role of biogeography in the analysis of species distribution. Key Takeaways Key Points The composition of plant and animal communities change as abiotic factors, which include temperature and altitude, start to vary.
Some species exist only in specific geographical areas while others can thrive in a variety of areas; however, no single species can be found everywhere in the world.
Studying an area where a species is not found is also of importance to ecologists in determining unique patterns of species distribution. As with animals, plant species can also be either endemic, usually found in isolated land masses, or generalists, found in many regions.
Key Terms biogeography : the study of the geographical distribution of living things generalist : species which can thrive in a wide variety of environmental conditions endemic : unique to a particular area or region; not found in other places. Energy Sources The availability of energy and nutrient sources affects species distribution and their adaptation to land or aquatic habitats. Learning Objectives Assess how energy availability affects species distribution within an ecosystem.
Key Takeaways Key Points In land habitats, plant adaptations include life cycles that are dependent on the availability of light; for example, species will flower or grow at varying times to ensure they capture enough available light suitable to their needs.
In aquatic ecosystems, species growth and distribution are adapted to deal with the sometimes-limited availability of light due to its absorption by water, plants, suspended particles, microorganisms, and water depth.
Ocean upwelling and spring and fall turnovers are important processes regulating the distribution of nutrients in an aquatic ecosystems. Nutrient availability is connected to the energy needs of organisms in aquatic ecosystems since sequestered energy is reused by living organisms from dead ones.
Key Terms ephemeral : lasting for a short period of time upwelling : the oceanographic phenomenon that occurs when strong, usually seasonal, winds push water away from the coast, bringing cold, nutrient-rich deep waters up to the surface thermocline : a layer within a body of water or air where the temperature changes rapidly with depth.
Temperature and Water Temperature and water are important abiotic factors that affect species distribution. Learning Objectives Describe species adaptations to temperature fluctuations and the availability of water. Key Takeaways Key Points Temperature is a factor that influences species distribution because organisms must either maintain a specific internal temperature or inhabit an environment that will keep the body within a temperature range that supports their metabolism.
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Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Microbial Ecology Marine Biodiversity Advanced search. Skip to main content Thank you for visiting nature. Download PDF. Subjects Biogeography Climate-change ecology Microbial ecology Population dynamics. Abstract Habitat availability and environmental preferences of species are among the most important factors in determining the success of dispersal processes and therefore in shaping the distribution of protists.
Introduction General biogeographic patterns of free-living protists are still a subject of debate. Database The number of colonies from each species in each sample was recorded in a database, also containing microhabitat type and spatial coordinates of the localities. Figure 1. Full size image. Results Maxent Variables selected for each species model and their relative contributions are shown in Table 1.
Table 1 Results of the maxent environmental niche models Full size table. Figure 2. Figure 3. Similar conditions occur on the west coast of continents in the Atlantic and Indian Oceans.
These regions are the primary source of mixing between warmer surface waters and colder deep waters, which ordinarily remain separate. The upwelling of nutrient-rich water contributes to the unusually high biological productivity of the coastal waters in these regions.
Figure 4: Upwelling As the trade winds blow warm surface waters away from the west coast of continents, cold, nutrient-rich water is drawn to the surface. Just as Earth's rotation creates the prevailing winds, it creates surface currents within the oceans. Under the influence of the trade winds, surface waters near the equator flow from east to west. As in the atmosphere, the Coriolis force causes water to be deflected away from the equator northward in the Northern Hemisphere, southward in the Southern Hemisphere.
This Coriolis Effect sets up a rotational convection within the oceans, and currents typically flow in a clockwise rotation in the Northern Hemisphere and in a counter-clockwise direction in the Southern Hemisphere. As it reaches the poles, the water cools and sinks. Prevailing winds in northern and southern latitudes help to create cold-water surface currents that flow back toward the equator along the west coast of continents.
Surface waters freeze as they reach the arctic waters of the North Atlantic. The freezing process removes water molecules, but not salt, from the ocean. The result is an increase in the salinity of ocean waters.
This process sets up a large, slow, deep-water "conveyor belt" that transports water along the ocean floor to Antarctica then through the Indian, Pacific, and eventually Atlantic oceans. The combination of oceanic and atmospheric circulation drives global climate by redistributing heat and moisture. Areas located near the tropics remain warm and relatively wet throughout the year.
In temperate regions, variation in solar input drives seasonal changes. In the Northern Hemisphere where land masses are more concentrated, these seasons can involve pronounced changes in temperature. In the Southern Hemisphere where large land masses are located nearer to the equator and the majority of Earth's surface is covered with water, seasonal cycles revolve around the presence and absence of precipitation rather than major swings in temperature.
Global climate patterns are dynamic: They are continually changing in response to solar radiation, atmospheric greenhouse gas concentrations, and other climate forcing factors. Among the more predictable of these changes are cyclical changes in solar radiation reaching the poles. These cycles, first described by Milutin Milankovitch , involve Earth's orbit, tilt, and the precession of the equinoxes.
Earth's elliptical orbit around the sun shifts under the gravitational pull of other planets in our solar system. In a ,year cycle, the orbit shifts from one that is nearly circular to one that is elongated, pulling the planet further from its energy source Figure 5A. Earth's tilt relative to its orbit changes in a 41,year cycle from Finally, the axis north-south orientation of the Earth wobbles over time.
This 23,year precession of the equinoxes changes the orientation of the planet relative to its location in orbit Figure 5C. When all three Milankovitch cycles reinforce each other, they alter solar input and influence oceanic and atmospheric circulation patterns. This can lead to regular periods of cooling and glaciation. Figure 5: Milankovitch cycles A High eccentricity in Earth's orbit takes it further away from the sun.
B The degree of Earth's tilt relative to its plane of orbit changes the degree of warming in the polar regions.
C Precession of the equinoxes occurs as Earth wobbles on its axis. All three cycles can influence warming and cooling periods by altering the amount of solar radiation that reaches Earth. Periods of cooling can be intensified through albedo; the presence of snow and ice reflects incident sunlight and heat, which serves to further cool the planet.
In this way, glaciers and polar ice caps continue to grow during periods when incident sunlight is low. As more water becomes locked up as ice, the surface level of oceans drops, which can alter oceanic circulation patterns.
In addition, movement of continental land masses through the processes of plate tectonics can shift the flow of water, altering ocean currents and circulation patterns. As Earth's precession and tilt increase polar exposure to sunlight, rapid melting events can occur. Freed from the grip of ice, soils thaw and previously frozen vegetation decays, releasing both carbon dioxide and methane gas — two noted greenhouse gases — into the atmosphere.
Increases in carbon dioxide and methane in the atmosphere help to further warm the earth, and these gases are thought to have contributed to historical rapid warming events.
The current distribution of plants and animals reflects historical changes in both global climatic conditions and the location of land masses. During cold periods, when much of the land was covered in snow and ice, the amount of land available for terrestrial organisms to inhabit decreased, increasing competition for resources. As the ice retreated during warming events, organisms migrated to fill newly-available areas, and many species flourished under the new environmental conditions.
Over time, organisms evolved adaptations that better enabled them to exploit their new surroundings. Some of those adaptations persist in their modern-day descendants. While climatic conditions were changing, so were the locations of large land masses as they shifted under the influence of magma currents beneath the crust. Continental collisions built mountain ranges and widening rifts became seas, both of which served to create barriers to organismal dispersal, restricting the ability of organisms to migrate.
Restricted to smaller areas, organisms evolved traits that best suited them to the environmental conditions of their continent and region. Today we recognize six biogeographic realms — Nearctic, Palearctic, Neotropical, Ethiopian, Oriental, and Australian — in which animals exhibit features distinctive to that region Figure 6. Realms that have experienced barriers to dispersal for longer periods of time contain animals with more distinctive traits.
One of the best examples of this can be seen in the marsupial mammals of the Australian Region, which has a long history of isolation from other continents. Figure 6: Biogeographic realms Variation in climate and presence of barriers to dispersal has led to six major realms of organisms. The realms are not clearly delineated, rather species mix along boundaries.
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