1.
Populus tremuloides
–
Populus tremuloides is a deciduous tree native to cooler areas of North America, one of several species referred to by the common name aspen. It is commonly called quaking aspen, trembling aspen, American aspen, Quakies, mountain or golden aspen, trembling poplar, white poplar, popple, the trees have tall trunks, up to 25 meters tall, with smooth pale bark, scarred with black. The glossy green leaves, dull beneath, become golden to yellow, rarely red, the species often propagates through its roots to form large groves originating from a shared system of rhizomes. Populus tremuloides is the most widely distributed tree in North America and it is the defining species of the aspen parkland biome in the Prairie Provinces of Canada and extreme northwest Minnesota. The quaking or trembling of the leaves that is referred to in the names is due to the flexible flattened petioles. The specific epithet, tremuloides, evokes this trembling behavior and can be translated as like tremula. Some species of Populus have petioles flattened partially along their length, while the aspens and some other poplars have them flattened from side to side along the entire length of the petiole. Quaking aspen is a tall, fast growing tree, usually 20–25 m at maturity, with a trunk 20 to 80 cm in diameter, the bark is relatively smooth, colored greenish-white to gray, and is marked by thick black horizontal scars and prominent black knots. Parallel vertical scars are tell-tale signs of elk, which strip off bark with their front teeth. The leaves on trees are nearly round, 4–8 centimeters in diameter with small rounded teeth. Young trees and root sprouts have much larger nearly triangular leaves, aspens are dioecious, with separate male and female clones. The quaking aspen is the State Tree of Utah, quaking aspen occurs across Canada in all provinces and territories, with the possible exception of Nunavut. It occurs at low elevations as far south as northern Nebraska, in the western United States, this tree rarely survives at elevations lower than 1,500 feet due to hot summers experienced below that elevation, and is generally found at 5, 000–12,000 feet. It grows at altitudes as far south as Guanajuato, Mexico. Quaking aspen grows in a variety of climatic conditions. January and July average temperatures range from −30 °C and 16 °C in the Alaska Interior to −3 °C and 23 °C in Fort Wayne, average annual precipitation ranges from 1,020 mm in Gander, Newfoundland and Labrador to as little as 180 mm in the Alaska Interior. The southern limit of the range roughly follows the 24 °C mean July isotherm. Shrub-like dwarf clones exist in environments too cold and dry to be hospitable to full-size trees
2.
Tree
–
In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are usable as lumber or plants above a specified height. Trees are not a group but include a variety of plant species that have independently evolved a woody trunk. In looser senses, the palms, the tree ferns, bananas. Trees tend to be long-lived, some reaching several thousand years old, the tallest known tree, a coast redwood named Hyperion, stands 115.6 m high. Trees have been in existence for 370 million years and it is estimated that there are just over 3 trillion mature trees in the world. A tree typically has many secondary branches supported clear of the ground by the trunk and this trunk typically contains woody tissue for strength, and vascular tissue to carry materials from one part of the tree to another. For most trees it is surrounded by a layer of bark which serves as a protective barrier, below the ground, the roots branch and spread out widely, they serve to anchor the tree and extract moisture and nutrients from the soil. Above ground, the divide into smaller branches and shoots. The shoots typically bear leaves, which light energy and convert it into sugars by photosynthesis, providing the food for the trees growth. Flowers and fruit may also be present, but some trees, such as conifers, instead have pollen cones and seed cones, others, such as tree ferns, trees play a significant role in reducing erosion and moderating the climate. They remove carbon dioxide from the atmosphere and store large quantities of carbon in their tissues, trees and forests provide a habitat for many species of animals and plants. Tropical rainforests are one of the most biodiverse habitats in the world, trees provide shade and shelter, timber for construction, fuel for cooking and heating, and fruit for food as well as having many other uses. In parts of the world, forests are shrinking as trees are cleared to increase the amount of available for agriculture. Because of their longevity and usefulness, trees have always revered, with sacred groves in various cultures. Although tree is a term of common parlance, there is no universally recognised precise definition of what a tree is, either botanically or in common language. In its broadest sense, a tree is any plant with the form of an elongated stem, or trunk. Trees are also defined by height, with smaller plants from 0.5 to 10 m being called shrubs
3.
Populus
–
Populus is a genus of 25–35 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar /ˈpɒp. lər/, aspen, in the September 2006 issue of Science Magazine, the Joint Genome Institute announced that the western balsam poplar was the first tree whose full DNA code had been determined by DNA sequencing. The genus has a genetic diversity, and can grow from 15–50 m tall. The shoots are stout, with the terminal bud present, leaf size is very variable even on a single tree, typically with small leaves on side shoots, and very large leaves on strong-growing lead shoots. The leaves often turn bright gold to yellow before they fall during autumn, the flowers are mostly dioecious and appear in early spring before the leaves. They are borne in long, drooping, sessile or pedunculate catkins produced from buds formed in the axils of the leaves of the previous year. The flowers are each seated in a disk which is borne on the base of a scale which is itself attached to the rachis of the catkin. The scales are obovate, lobed, and fringed, membranous, hairy or smooth, the female flower also has no calyx or corolla, and comprises a single-celled ovary seated in a cup-shaped disk. The style is short, with two to four stigmata, variously lobed, and numerous ovules, pollination is by wind, with the female catkins lengthening considerably between pollination and maturity. Poplars of the section are often wetlands or riparian trees. The aspens are among the most important boreal broadleaf trees, Poplars and aspens are important food plants for the larvae of a large number of Lepidoptera species. Pleurotus populinus, the oyster mushroom, is found exclusively on dead wood of Populus trees in North America. The genus Populus has traditionally divided into six sections on the basis of leaf and flower characters. Recent genetic studies have supported this, confirming some previously suspected reticulate evolution due to past hybridisation and introgression events between the groups. Some species had differing relationships indicated by their nuclear DNA and chloroplast DNA sequences and they have the advantage of growing to a very large size at a rapid pace. Almost all poplars take root readily from cuttings or where broken branches lie on the ground, trees with fastigiate branching are particularly popular, and are widely grown across Europe and southwest Asia. Common poplar varieties are, G48 w22 The trees are grown from kalam or cuttings, harvested annually in January and February, most commonly used to make plywood, Yamuna Nagar in Haryana state has a large plywood industry reliant upon poplar. It is graded according to known as over, under
4.
Deciduous
–
In a more general sense, deciduous means the dropping of a part that is no longer needed or falling away after its purpose is finished. In plants it is the result of natural processes, in botany and horticulture, deciduous plants, including trees, shrubs and herbaceous perennials, are those that lose all of their leaves for part of the year. In some cases leaf loss coincides with winter—namely in temperate or polar climates, in other parts of the world, including tropical, subtropical, and arid regions, plants lose their leaves during the dry season or other seasons, depending on variations in rainfall. The converse of deciduous is coniferous, where foliage is shed on a different schedule from deciduous trees, plants that are intermediate may be called semi-deciduous, they lose old foliage as new growth begins. Other plants are semi-evergreen and lose their leaves before the growing season. Many deciduous plants flower during the period when they are leafless, the absence of leaves improves wind transmission of pollen for wind-pollinated plants and increases the visibility of the flowers to insects in insect-pollinated plants. This strategy is not without risks, as the flowers can be damaged by frost or, in dry season regions, leaf drop or abscission involves complex physiological signals and changes within plants. The process of photosynthesis steadily degrades the supply of chlorophylls in foliage, the brightest leaf colors are produced when days grow short and nights are cool, but remain above freezing. These other pigments include carotenoids that are yellow, brown, anthocyanin pigments produce red and purple colors, though they are not always present in the leaves. Rather, they are produced in the foliage in late summer, parts of the world that have showy displays of bright autumn colors are limited to locations where days become short and nights are cool. In other parts of the world, the leaves of deciduous trees simply fall off without turning the bright colors produced from the accumulation of anthocyanin pigments, the beginnings of leaf drop starts when an abscission layer is formed between the leaf petiole and the stem. This layer is formed in the spring during active new growth of the leaf, the cells are sensitive to a plant hormone called auxin that is produced by the leaf and other parts of the plant. The elongation of cells break the connection between the different cell layers, allowing the leaf to break away from the plant. It also forms a layer that seals the break, so the plant does not lose sap, in the spring, these proteins are used as a nitrogen source during the growth of new leaves or flowers. Plants with deciduous foliage have advantages and disadvantages compared to plants with evergreen foliage, evergreens suffer greater water loss during the winter and they also can experience greater predation pressure, especially when small. Losing leaves in winter may reduce damage from insects, repairing leaves, removing leaves also reduces cavitation which can damage xylem vessels in plants. This then allows deciduous plants to have xylem vessels with larger diameters, the deciduous characteristic has developed repeatedly among woody plants. Trees include maple, many oaks and nothofagus, elm, aspen, Deciduous shrubs include honeysuckle, viburnum, and many others
5.
Lenticel
–
It functions as a pore, providing a pathway for the direct exchange of gases between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gases. The name lenticel, pronounced with an, derives from its lenticular shape, the shape of lenticels is one of the characteristics used for tree identification. Lenticel formation usually begins beneath stomatal complexes during primary growth preceding the development of the first periderm, lenticels are found as raised circular, oval, or elongated areas on stems and roots. As stems and roots mature lenticel development continues in the new periderm, lenticels are also found in pneumatophorous roots. Lenticels are also present on many fruits, quite noticeably on many apples, “Lenticel breakdown” is a global skin disorder of apples in which lenticels develop dark 1–8 mm diameter pits shortly after processing and packing. It is most common on the variety, particularly the ‘Royal Gala’, and also occurs in ‘Fuji’, ‘Granny Smith’, ‘Golden Delicious’. It is more common in regions, and is thought to be related to relative humidity. The effect can be mitigated by spraying the fruit with lipophilic coatings prior to harvest, lenticels are also present on potato tubers. Raven, Peter H. Ray F. Evert, Susan E. Eichorn
6.
Stoma
–
In botany, a stoma, also called a stomate, is a pore, found in the epidermis of leaves, stems, and other organs, that is used to control gas exchange. The pore is bordered by a pair of specialized cells known as guard cells that are responsible for regulating the size of the stomatal opening. The term is used collectively to refer to the entire stomatal complex, consisting of the paired guard cells and the pore itself. Air enters the plant through these openings by gaseous diffusion, and contains carbon dioxide and oxygen, oxygen produced as a by-product of photosynthesis diffuses out to the atmosphere through these same openings. Also, water vapor is released into the atmosphere through these pores in a process called transpiration, stomata are present in the sporophyte generation of all land plant groups except liverworts. Dicotyledons usually have more stomata on the lower epidermis than the upper epidermis, monocotyledons, on the other hand, usually have the same number of stomata on the two epidermes. In plants with floating leaves, stomata may be only on the upper epidermis. Most tree species have leaves only on the lower surface, size varies across species, with end-to-end lengths ranging from 10 to 80 µm and width ranging from a few to 50 µm. Carbon dioxide, a key reactant in photosynthesis, is present in the atmosphere at a concentration of about 400 ppm, most plants require the stomata to be open during daytime. The air spaces in the leaf are saturated with water vapour, which exits the leaf through the stomata, therefore, plants cannot gain carbon dioxide without simultaneously losing water vapour. Ordinarily, carbon dioxide is fixed to ribulose-1, 5-bisphosphate by the enzyme RuBisCO in mesophyll cells exposed directly to the air spaces inside the leaf. For both of these reasons, RuBisCo needs high carbon dioxide concentrations, which means wide stomatal apertures and, as a consequence, narrower stomatal apertures can be used in conjunction with an intermediary molecule with a high carbon dioxide affinity, PEPcase. Retrieving the products of carbon fixation from PEPCase is in an energy-intensive process, a group of mostly desert plants called CAM plants open their stomata at night, use PEPcarboxylase to fix carbon dioxide and store the products in large vacuoles. The following day, they close their stomata and release the carbon dioxide fixed the previous night into the presence of RuBisCO and this saturates RuBisCO with carbon dioxide, allowing minimal photorespiration. This approach, however, is limited by the capacity to store fixed carbon in the vacuoles. It is not entirely certain how these responses work, however, the basic mechanism involves regulation of osmotic pressure. When conditions are conducive to stomatal opening, a proton pump drives protons from the guard cells and this means that the cells electrical potential becomes increasingly negative. The negative potential opens potassium voltage-gated channels and so an uptake of ions occurs
7.
Rhizome
–
In botany and dendrology, a rhizome is a modified subterranean stem of a plant that is usually found underground, often sending out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks and rootstocks, Rhizomes develop from axillary buds and are diageotropic or grow perpendicular to the force of gravity. The rhizome also retains the ability to new shoots to grow upwards. If a rhizome is separated into pieces, each piece may be able to rise to a new plant. The plant uses the rhizome to store starches, proteins, and these nutrients become useful for the plant when new shoots must be formed or when the plant dies back for the winter. This is a known as vegetative reproduction and is used by farmers and gardeners to propagate certain plants. This also allows for lateral spread of grasses like bamboo and bunch grasses, examples of plants that are propagated this way include hops, asparagus, ginger, irises, Lily of the Valley, cannas, and sympodial orchids. Some rhizomes which are used directly in cooking include ginger, turmeric, galangal, stored rhizomes are subject to bacterial and fungal infections, making them unsuitable for replanting and greatly diminishing stocks. However, rhizomes can also be produced artificially from tissue cultures, the ability to easily grow rhizomes from tissue cultures leads to better stocks for replanting and greater yields. The plant hormones ethylene and jasmonic acid have found to help induce and regulate the growth of rhizomes. Ethylene that was applied externally was found to affect internal ethylene levels, knowledge of how to use these hormones to induce rhizome growth could help farmers and biologists producing plants grown from rhizomes more easily cultivate and grow better plants. The poplars are an example of trees that propagate using a rhizome, the Pando colony in Utah is a famous example, which has been living for about 80,000 years. In general, rhizomes have short internodes, they send out roots from the bottom of the nodes, a stem tuber is a thickened part of a rhizome or stolon that has been enlarged for use as a storage organ. In general, a tuber is high in starch, for example, the common potato, the term tuber is often used imprecisely, and is sometimes applied to plants with rhizomes. Some plants have rhizomes that grow above ground or that lie at the surface, including some Iris species. Rhizomes generally form a layer, but in Giant Horsetails. Many rhizomes have culinary value, and some, such as zheergen, are consumed raw. Aspen Corm Mycorrhiza Media related to Rhizomes at Wikimedia Commons
8.
Root
–
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. Roots can also be aerial or aerating, that is growing up above the ground or especially above water, furthermore, a stem normally occurring below ground is not exceptional either. Therefore, the root is best defined as the non-leaf, non-nodes bearing parts of the plants body, however, important internal structural differences between stems and roots exist. The fossil record of roots – or rather, infilled voids where roots rotted after death – spans back to the late Silurian and their identification is difficult, because casts and molds of roots are so similar in appearance to animal burrows. They can be discriminated using a range of features, the first root that comes from a plant is called the radicle. In response to the concentration of nutrients, roots also synthesise cytokinin, Roots often function in storage of food and nutrients. The roots of most vascular plant species enter into symbiosis with fungi to form mycorrhizae. In its simplest form, the root architecture refers to the spatial configuration of a plant’s root system. This system can be complex and is dependent upon multiple factors such as the species of the plant itself, the composition of the soil. The configuration of root systems serves to support the plant, compete with other plants. Roots grow to specific conditions, which, if changed, can impede a plants growth. For example, a system that has developed in dry soil may not be as efficient in flooded soil, yet plants are able to adapt to other changes in the environment. Root architecture plays the important role of providing a supply of nutrients and water as well as anchorage. The main terms used to classify the architecture of a system are, Branch magnitude. Root angle, the angle of a lateral root’s base around the parent root’s circumference, the angle of a lateral root from its parent root. Link radius, the diameter of a root, all components of the root architecture are regulated through a complex interaction between genetic responses and responses due to environmental stimuli. These developmental stimuli are categorised as intrinsic, the genetic and nutritional influences, or extrinsic, the main hormones and respective pathways responsible for root architecture development include, Auxin – Auxin promotes root initiation, root emergence and primary root elongation. Cytokinins – Cytokinins regulate root apical meristem size and promote lateral root elongation, gibberellins – Together with ethylene they promote crown primordia growth and elongation
9.
Wildfire
–
A wildfire or wildland fire is a fire in an area of combustible vegetation that occurs in the countryside or rural area. Fossil charcoal indicates that wildfires began soon after the appearance of terrestrial plants 420 million years ago, wildfire’s occurrence throughout the history of terrestrial life invites conjecture that fire must have had pronounced evolutionary effects on most ecosystems flora and fauna. Earth is an intrinsically flammable planet owing to its cover of vegetation, seasonally dry climates, atmospheric oxygen, widespread lightning. Wildfires can be characterised in terms of the cause of ignition, their properties, the combustible material present. Wildfires can cause damage to property and human life, but they have beneficial effects on native vegetation, animals. Many plant species depend on the effects of fire for growth, however, wildfire in ecosystems where wildfire is uncommon or where non-native vegetation has encroached may have negative ecological effects. Wildfire behaviour and severity result from the combination of such as available fuels, physical setting. Strategies of wildfire prevention, detection and suppression have varied over the years, one common and inexpensive technique is controlled burning, permitting or even igniting smaller fires to minimise the amount of flammable material available for a potential wildfire. Vegetation may be burned periodically to maintain species diversity and frequent burning of surface fuels limits fuel accumulation. Wildland fire use is the cheapest and most ecologically appropriate policy for many forests, fuels may also be removed by logging, but fuels treatments and thinning have no effect on severe fire behaviour. Wildfires can also be started in communities experiencing shifting cultivation, where land is cleared quickly and farmed until the soil loses fertility, forested areas cleared by logging encourage the dominance of flammable grasses, and abandoned logging roads overgrown by vegetation may act as fire corridors. The most common cause of wildfires throughout the world. In Canada and northwest China, for example, lightning operates as the source of ignition. In other parts of the world, human involvement is a major contributor, in China and in the Mediterranean Basin, human carelessness is a major cause of wildfires. In the United States and Australia, the source of wildfires can be traced both to lightning strikes and to human activities. Coal seam fires burn in the thousands around the world, such as those in Burning Mountain, New South Wales, Centralia, Pennsylvania and they can also flare up unexpectedly and ignite nearby flammable material. The spread of wildfires based on the flammable material present, its vertical arrangement and moisture content. Fuel arrangement and density is governed in part by topography, as land shape determines factors such as available sunlight, overall, fire types can be generally characterized by their fuels as follows, Ground fires are fed by subterranean roots, duff and other buried organic matter
10.
Reforestation
–
Reforestation is the natural or intentional restocking of existing forests and woodlands that have been depleted, usually through deforestation. Sometimes the term re-afforestation is used to distinguish between the original forest cover and the later re-growth of forest to an area, forestation is the establishment of forest growth on areas that either had forest or lacked it. Special tools, e. g. tree planting bars, are used to make planting of trees easier and faster, a debated issue in managed reforestation is whether or not the succeeding forest will have the same biodiversity as the original forest. If the forest is replaced with one species of tree and all other vegetation is prevented from growing back. However, most reforestation involves the planting of different seedlots of seedlings taken from the area, another important factor is the natural regeneration of a wide variety of plant and animal species that can occur on a clear cut. In some areas the suppression of forest fires for hundreds of years has resulted in large single aged, the logging of small clear cuts and/or prescribed burning, actually increases the biodiversity in these areas by creating a greater variety of tree stand ages and species. Reforestation need not be used for recovery of accidentally destroyed forests. In some countries, such as Finland, many of the forests are managed by the products and pulp. In such an arrangement, like other crops, trees are planted to replace those that have been cut, in such circumstances, the industry can cut the trees in a way to allow easier reforestation. The wood products industry systematically replaces many of the trees it cuts, for example, in 2010, Weyerhaeuser reported planting 50 million seedlings. However replanting an old-growth forest with a plantation is not replacing the old with the characteristics in the new. In just 20 years, a plantation in Costa Rica can produce up to about 400 m³ of wood per hectare. As the natural forests of Asia become more scarce or difficult to obtain. Other species such as mahogany grow more slowly than teak in Tropical America but are extremely valuable. Faster growers include pine, eucalyptus, and Gmelina, the reestablishment of forests is not just simple tree planting. Forests are made up of a community of species and they build dead organic matter into soils over time, a major tree-planting program could enhance the local climate and reduce the demands of burning large amounts of fossil fuels for cooling in the summer. Forests are an important part of the carbon cycle because trees. By removing this greenhouse gas from the air, forests function as terrestrial carbon sinks, at any time, forests account for as much as double the amount of carbon in the atmosphere
11.
Sowing
–
Sowing is the process of planting seeds. An area or object that has had seeds planted will be described as being sowed, among the major field crops, oats, wheat, and rye are sown, grasses and legumes are seeded and maize and soybeans are planted. In sowing, little if any soil is placed over the seeds, more precisely, seeds can be generally sown into the soil by maintaining a planting depth of about 2-3 times the size of the seed. This method is better, as more light may fall on the seedlings as they come out. Symmetrical grid pattern – using the pattern described in The Garden of Cyrus. Hand sowing or is the process of casting handfuls of seed over prepared ground, usually, a drag or harrow is employed to incorporate the seed into the soil. Though labor-intensive for any but small areas, this method is used in some situations. Practice is required to sow evenly and at the desired rate, a hand seeder can be used for sowing, though it is less of a help than it is for the smaller seeds of grasses and legumes. Hand sowing may be combined with pre-sowing in seed trays and this allows the plants to come to strength indoors during cold periods. In agriculture, most seed is now using a seed drill. The drill also places the seed at a distance below the soil. The standard design uses a fluted feed metering system, which is volumetric in nature, rows are typically about 10–30 cm apart, depending on the crop species and growing conditions. Several row opener types are used depending on type and local tradition. Grain drills are most often drawn by tractors, but can also be pulled by horses, pickup trucks are sometimes used, since little draft is required. A seed rate of about 100 kg of seed per hectare is typical, though rates vary depending on crop species, soil conditions. Excessive rates can cause the crop to lodge, while too thin a rate will result in poor utilisation of the land, competition with weeds and a reduction in the yield. The seed is left uncovered at the surface of the soil before germinating and therefore exposed to the prevailing climate. Before sowing, certain seeds first require a treatment prior to the sowing process and this treatment may be seed scarification, stratification, seed soaking or seed cleaning with cold water
12.
Climate change
–
Climate change is a change in the statistical distribution of weather patterns when that change lasts for an extended period of time. Climate change may refer to a change in weather conditions. Climate change is caused by such as biotic processes, variations in solar radiation received by Earth, plate tectonics. Certain human activities have also identified as significant causes of recent climate change. Scientists actively work to understand past and future climate by using observations, more recent data are provided by the instrumental record. The most general definition of change is a change in the statistical properties of the climate system when considered over long periods of time. Accordingly, fluctuations over periods shorter than a few decades, such as El Niño, the term climate change is often used to refer specifically to anthropogenic climate change. Anthropogenic climate change is caused by activity, as opposed to changes in climate that may have resulted as part of Earths natural processes. In this sense, especially in the context of environmental policy, within scientific journals, global warming refers to surface temperature increases while climate change includes global warming and everything else that increasing greenhouse gas levels affect. A related term is climatic change, in 1966, the World Meteorological Organization proposed the term climatic change to encompass all forms of climatic variability on time-scales longer than 10 years, regardless of cause. Change was a given and climatic was used as an adjective to describe this kind of change, when it was realized that human activities had a potential to drastically alter the climate, the term climate change replaced climatic change as the dominant term to reflect an anthropogenic cause. Climate change was incorporated in the title of the Intergovernmental Panel on Climate Change, Climate change, used as a noun, became an issue rather than the technical description of changing weather. On the broadest scale, the rate at which energy is received from the Sun and this energy is distributed around the globe by winds, ocean currents, and other mechanisms to affect the climates of different regions. Factors that can shape climate are called climate forcings or forcing mechanisms, there are a variety of climate change feedbacks that can either amplify or diminish the initial forcing. Some parts of the system, such as the oceans and ice caps, respond more slowly in reaction to climate forcings. There are also key factors which when exceeded can produce rapid change. Forcing mechanisms can be internal or external. Internal forcing mechanisms are natural processes within the system itself
.JPG)
