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Sunfleck
Sunflecks are brief increases in solar irradiance that occur in understories of an ecosystem when sunlight is able to directly reach the ground. They are caused by either wind moving branches and/or leaves in the canopy or as the sun moves during the day. Although each sunfleck only last for seconds or minutes at a time, they can be responsible more than 80% of the photons that reach plants in the understory, and up to 35% of carbon fixation. This makes them important sources of energy for plants in the understory of forests. The amount of energy that a sunfleck provides depends on their duration, size and shape and the intensity of photosynthetically active radiation Photosynthetically active radiation (PAR) designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds more o ... (PAR), which itself depends on the arrangement of vegetation in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Irradiance
Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m2) in SI units. Solar irradiance is often integrated over a given time period in order to report the radiant energy emitted into the surrounding environment (joule per square metre, J/m2) during that time period. This integrated solar irradiance is called solar irradiation, solar exposure, solar insolation, or insolation. Irradiance may be measured in space or at the Earth's surface after atmospheric absorption and scattering. Irradiance in space is a function of distance from the Sun, the solar cycle, and cross-cycle changes.Michael Boxwell, ''Solar Electricity Handbook: A Simple, Practical Guide to Solar Energy'' (2012), p. 41–42. Irradiance on the Earth's surface additionally depends on the tilt of the measuring surface, the hei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Understory
In forestry and ecology, understory (American English), or understorey (Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the forest canopy without penetrating it to any great extent, but above the forest floor. Only a small percentage of light penetrates the canopy so understory vegetation is generally shade-tolerant. The understory typically consists of trees stunted through lack of light, other small trees with low light requirements, saplings, shrubs, vines and undergrowth. Small trees such as holly and dogwood are understory specialists. In temperate deciduous forests, many understory plants start into growth earlier in the year than the canopy trees, to make use of the greater availability of light at that particular time of year. A gap in the canopy caused by the death of a tree stimulates the potential emergent trees into competitive growth as they grow upwards to fill the gap. These trees tend to have straight trunks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photon
A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they always move at the speed of light in vacuum, (or about ). The photon belongs to the class of bosons. As with other elementary particles, photons are best explained by quantum mechanics and exhibit wave–particle duality, their behavior featuring properties of both waves and particles. The modern photon concept originated during the first two decades of the 20th century with the work of Albert Einstein, who built upon the research of Max Planck. While trying to explain how matter and electromagnetic radiation could be in thermal equilibrium with one another, Planck proposed that the energy stored within a material object should be regarded as composed of an integer number of discrete, equal-sized parts. To explain the photoelectric effect, Eins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Fixation
Biological carbon fixation or сarbon assimilation is the process by which inorganic carbon (particularly in the form of carbon dioxide) is converted to organic compounds by living organisms. The compounds are then used to store energy and as structure for other biomolecules. Carbon is primarily fixed through photosynthesis, but some organisms use a process called chemosynthesis in the absence of sunlight. Organisms that grow by fixing carbon are called autotrophs, which include photoautotrophs (which use sunlight), and lithoautotrophs (which use inorganic oxidation). Heterotrophs are not themselves capable of carbon fixation but are able to grow by consuming the carbon fixed by autotrophs or other heterotrophs. "Fixed carbon", "reduced carbon", and "organic carbon" may all be used interchangeably to refer to various organic compounds. Chemosynthesis is carbon fixation driven by chemical energy, rather than from sunlight. Sulfur- and hydrogen-oxidizing bacteria often use the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photosynthetically Active Radiation
Photosynthetically active radiation (PAR) designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds more or less with the range of light visible to the human eye. Photons at shorter wavelengths tend to be so energetic that they can be damaging to cells and tissues, but are mostly filtered out by the ozone layer in the stratosphere. Photons at longer wavelengths do not carry enough energy to allow photosynthesis to take place. Other living organisms, such as cyanobacteria, purple bacteria, and heliobacteria, can exploit solar light in slightly extended spectral regions, such as the near-infrared. These bacteria live in environments such as the bottom of stagnant ponds, sediment and ocean depths. Because of their pigments, they form colorful mats of green, red and purple. Chlorophyll, the most abundant plant pigment, is most efficient in capt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
