- Plants, Animals, and Ecosystems
- What’s at stake?
- Learn more
- Mountain ecosystem
- Water temperature for your plants
- Temperature extremes: Effect on plant growth and development
- Plant Growth and Overcrowdingby Science Made Simple
- Botany and Plant Growth Projects, Overcrowding
- The Effect of Temperature on the Rate of Photosynthesis
Plants, Animals, and Ecosystems
Most plants and animals live in areas with very specific climate conditions, such as temperature and rainfall patterns, that enable them to thrive. Any change in the climate of an area can affect the plants and animals living there, as well as the makeup of the entire ecosystem. Some species are already responding to a warmer climate by moving to cooler locations. For example, some North American animals and plants are moving farther north or to higher elevations to find suitable places to live. Climate change also alters the life cycles of plants and animals. For example, as temperatures get warmer, many plants are starting to grow and bloom earlier in the spring and survive longer into the fall. Some animals are waking from hibernation sooner or migrating at different times, too.
What’s at stake?
As the Earth gets warmer, plants and animals that need to live in cold places, like on mountaintops or in the Arctic, might not have a suitable place to live. If the Earth keeps getting warmer, up to one–fourth of all the plants and animals on Earth could become extinct within 100 years. Every plant and animal plays a role in the ecosystem (for example, as a source of food, a predator, a pollinator, a source of shelter), so losing one species can affect many others.
- What can people do about it?
Just like people, plants and animals will have to adapt to climate change. Many types of birds in North America are already migrating further north as the temperature warms. People can help these animals adapt by protecting and preserving their habitats.
Coral reefs are created in shallow tropical waters by millions of tiny animals called corals. Each coral makes a skeleton for itself, and over time, these skeletons build up to create coral reefs, which provide habitat for lots of fish and other ocean creatures. Warmer water has already caused coral bleaching (a type of damage to corals) in many parts of the world. By 2050, live corals could become rare in tropical and sub-tropical reefs due to the combined effects of warmer water and increased ocean acidity caused by more carbon dioxide in the atmosphere. The loss of coral reefs will reduce habitats for many other sea creatures, and it will disrupt the food web that connects all the living things in the ocean.
- What can people do about it?
To help give coral reefs a better chance of surviving the effects of climate change, swimmers, boaters, and divers should treat these fragile ecosystems with care. People can also support groups working to protect coral reefs.
- Take an expedition to the Arctic to learn more about how climate change will affect wildlife that depends on sea ice.
- Take an expedition to Australia’s Great Barrier Reef to learn more about how climate change threatens coral reefs.
- Check out Climate Change Wildlife and Wildlands: A Toolkit for Formal and Informal Educators to explore the effects of climate change on wildlife in 11 different parts of the United States.
- Find out more about how people can help plants, animals, and ecosystems deal with climate change.
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Mountain environments have different climates from the surrounding lowlands, and hence the vegetation differs as well. The differences in climate result from two principal causes: altitude and relief. (For more information see climate: Climatic classification: World distribution of major climatic types: Highland climates.) Altitude affects climate because atmospheric temperature drops with increasing altitude by about 0.5 to 0.6 °C (0.9 to 1.1 °F) per 100 metres (328 feet). The relief of mountains affects climate because they stand in the path of wind systems and force air to rise over them. As the air rises it cools, leading to higher precipitation on windward mountain slopes (orographic precipitation); as it descends leeward slopes it becomes warmer and relative humidity falls, reducing the likelihood of precipitation and creating areas of drier climate (rain shadows).
While these general principles apply to all mountains, particular mountain climates vary. For instance, mountains in desert regions receive little rain because the air is almost always too dry to permit precipitation under any conditions—e.g., the Ahaggar Mountains in southern Algeria in the middle of the Sahara. Latitude also can affect mountain climates. On mountains in equatorial regions winter and summer are nonexistent, although temperatures at high altitude are low. Above about 3,500 metres frost may form any night of the year, but in the middle of every day temperatures warm substantially beneath the nearly vertical tropical sun, thus producing a local climate of “winter every night and spring every day.” For example, at an altitude of 4,760 metres in Peru, temperatures range from an average minimum of about −2 °C (28 °F) to average maximum values of 5 to 8 °C (41 to 46 °F) in every month of the year.
By contrast, mountains at temperate latitudes have strongly marked seasons. Above the tree line during the summer season, temperatures high enough for plant growth occur for only about 100 days, but this period may be virtually frost-free even at night. During the long winter, however, temperatures may remain below freezing day and night. Snow accumulation and the phenomena this type of precipitation may cause, such as avalanching, are important ecological factors in temperate but not tropical mountain regions.
Microclimate variations are also important in mountain regions, with different aspects of steep slopes exhibiting contrasting conditions due to variations in precipitation and solar energy receipt. In temperate regions mountain slopes facing the Equator—southward in the Northern Hemisphere and northward in the Southern Hemisphere—are significantly warmer than opposite slopes. This can directly and indirectly influence the vegetation; the length of time snow remains on the ground into spring affects when vegetation will emerge, and this in turn affects the land’s utility for grazing. Even in the tropics, aspect-related climate and vegetation contrasts occur, in spite of the midday vertical position of the sun. In New Guinea, for example, slopes facing east are warmer and drier and support certain plants at higher altitudes than slopes facing west, because the prevailing pattern of clear, sunny mornings and cloudy afternoons affects the amount of solar energy received by these contrasting aspects.
Mountain soils are usually shallow at higher altitudes, partly because the soil has been scraped off by the ice caps that formed on most high mountains throughout the world during the last glacial interval that ended about 10,000 years ago. Soils are generally poor in nutrients important to plants, especially nitrogen. Rapid erosion of loose materials is also common and is exacerbated by frost heaving, steep slopes, and, in temperate regions, substantial runoff of meltwater in spring. Soil is virtually absent on rocky peaks and ridges. However, because of the cool, wet climate, many mountain areas accumulate peat, which creates local deep, wet, acidic soils. In volcanic regions tephra (erupted ash) may also contribute to soil depth and fertility.
Considering the wide geographic extent of mountains and their resultant geologic and climatic variability, it is remarkable that they exhibit such a clear overall pattern in vegetation. The major structural feature of vegetation on mountains in all regions—except in very dry or very cold places—is tree line. (This characteristic is sometimes called timberline or forest limit, although strictly speaking the former term refers to the uppermost reaches that commercial-size timber trees attain and the latter term refers to a closed forest.) Above a critical level, which may vary between slopes on the same mountain and which is much higher on mountains at lower latitude, the climate becomes too harsh to permit tree growth; beyond that level grows alpine vegetation, dominated by herbaceous plants, such as grasses and forbs, or by low shrubs.
In general, the altitude at which the tree line occurs is determined by that at which the mean temperature in the warmest month approximates 10 °C (50 °F), provided moisture is not a limiting factor. This is not precisely the case under all circumstances, however; for example, in some tropical regions that have a yearlong growing season, forests can grow in conditions slightly cooler than this. Nevertheless, the value holds true in most regions, especially in the temperate zones. It reflects a fundamental requirement for a sufficient level of photosynthesis to occur to support the growth of tree trunks.
A relatively narrow belt of intermediate or mixed vegetation—the subalpine—usually exists between the forests below and the alpine vegetation above. In the subalpine of temperate mountains, stunted, usually infertile individuals of various tree species survive, despite blasts of windblown snow, frost damage, and desiccation. These deformed shrub-size trees are called krummholz.
Although the overall pattern in which forest gives way to alpine vegetation is common to mountains at all latitudes, the factors responsible for it are not the same in all places. In temperate-zone mountains, the brevity of the growing season is of paramount importance because tree shoot tissues that have had insufficient time to harden before growth ceases and winter conditions begin may die when frozen. Other factors that damage or kill shoots or entire trees in winter in this region at temperate latitudes include the abrasion of buds by windblown snow crystals, desiccation of shoots just above the snowpack where they are exposed to direct and snow-reflected solar radiation—especially late in winter as the sun angle rises—and infection of shoots beneath the snow by snow fungus. Freezing injury to roots may also occur if the insulating layer of snow is blown from the ground surface.
In the tropics, these phenomena are not experienced. Snowfall is not restricted to a single winter season, and when it occurs it usually melts quickly. Snow therefore does not accumulate as a thick, continuous cover except at altitudes above the upper limit of most plant life. For example, in Venezuela the tree line lies below 4,000 metres, even where there has been no human disturbance, but virtually permanent snowpatches are not encountered until about 5,000 metres, where no vascular plants survive. Tree line in tropical regions is a consequence of low maximum temperatures throughout the year. However, the microclimate near the ground is warmer, allowing prostrate shrubs to grow at altitudes well above the highest trees.
Water temperature for your plants
When watering your plants, it is essential to use water at the right temperature. This is because the roots of your plants are very sensitive to extremes of temperature. Using water that is too hot or too cold can put your plant under stress and cause damage.
The optimum temperature for roots to absorb water and nutrients is around 68°F. At that temperature, the water in the substrate still contains a lot of oxygen, and it is also exactly the right temperature to trigger the pump mechanism in the roots. At lower temperatures, the pump mechanism will not work as effectively, while at higher temperatures the plant is less able to take up oxygen from the water. Additionally, higher temperatures and a lack of oxygen can cause an increase in harmful moulds (such as Pythium) and bacteria, and all the problems that associated with those.
So it’s very important to maintain the right temperature in your substrate. Unfortunately, you can’t regulate the temperature of the substrate through watering. To do that, you would need to use extremely hot or cold water, and as we mentioned, that would put the plant under stress; and in any case, a quarter of an hour later, the temperature in the substrate would be back to what it was before watering.
Read also: How to grow hydro: 10 rules of thumb on watering plants
Temperature extremes: Effect on plant growth and development
Temperature is a primary factor affecting the rate of plant development. Warmer temperatures expected with climate change and the potential for more extreme temperature events will impact plant productivity. Pollination is one of the most sensitive phenological stages to temperature extremes across all species and during this developmental stage temperature extremes would greatly affect production. Few adaptation strategies are available to cope with temperature extremes at this developmental stage other than to select for plants which shed pollen during the cooler periods of the day or are indeterminate so flowering occurs over a longer period of the growing season. In controlled environment studies, warm temperatures increased the rate of phenological development; however, there was no effect on leaf area or vegetative biomass compared to normal temperatures. The major impact of warmer temperatures was during the reproductive stage of development and in all cases grain yield in maize was significantly reduced by as much as 80−90% from a normal temperature regime. Temperature effects are increased by water deficits and excess soil water demonstrating that understanding the interaction of temperature and water will be needed to develop more effective adaptation strategies to offset the impacts of greater temperature extreme events associated with a changing climate.
Plant Growth and Overcrowdingby Science Made Simple
Botany and Plant Growth Projects, Overcrowding
11. Does crowding affect plant growth?
Determine the effects of growing plants close together vs. growing plants farther apart.
Materials: 6 medium-sized pots, 10 bean seeds, potting soil, water, ruler, large measuring cup, desk lamp, pencil.
- Fill all pots with an equal amount of potting soil. Be sure that the soil has been dampened with water.
- Using a pencil, make 5 holes about 2 centimeters (cm) deep in the soil of one pot.
- Place seeds in each hole making sure that they are spaced relatively close but equal distance from each other within the pot.
- Place the remaining 5 seeds, 1 in each of the remaining 5 pots, about 2 cm deep.
- Cover the seeds with soil.
- Place all the pots underneath a large desk lamp so that each pot receives full light. Be sure to water each plant as needed.
- The seeds will germinate in about 7 days, and you will be able to begin making stem measurements. Take measurements for 14 days. Note the difference in stem length for each plant and write down your observations.
Results: What differences did you observe between seedlings that were crowded and those that were not? (color of leaves, length of stems, etc.) What caused those differences?
12. Roots Restrictions
Does the amount of room a plant has for roots make a difference in how big a plant will grow, regardless of how much fertilizer the plant is given?
Plant seeds in a variety of different-sized containers using vermiculite or other soil-less material, so you will be able to give each plant a measured amount of fertilizer. Or plant a number of plants in the same size containers and vary the amount of fertilizer and see what happens. Be sure to use small enough containers so that root growth really will be constricted.
Effect of Mulch
13. Does Colored Mulch Affect Soil Temperature?
To determine if different colored plastic (or mulch) on the soil surface affects the temperature of soil.
Materials: Digital thermometer; potting soil; 8 pots; colored mulch in black, white, and red; window sill with full sun; tape. For the colored mulch, you can use different paint colors to paint black plastic, or you might use different colored plastic bags or mulch from the store.
- Fill pots with equal amounts of soil. Place 2 uncovered pots on the window sill where there is full sun.
- Cover 2 pots with black plastic, 2 pots with white plastic, and 2 pots with red plastic. Make sure the plastic covers the top of the pot, and tape it to the pot.
- Place these pots on the window sill.
- In 24 hours, record your first temperature measurements. You can do this by sticking the temperature probe in the drainage hole of the pot. For 10 days, record the temperatures for each pot in the morning and afternoon. Note the differences in temperature among the colors, and record observations.
Results: Which pot had the highest soil temperature? What color kept the soil the coolest? Why do you think that some mulch colors make the soil hotter or cooler? How does this affect plant growth (see project 14)?
14. Does Colored Mulch Affect the Growth Rate of a Plant?
To determine if colored plastic (mulch) will affect the stem length of plants.
Materials: Materials: 8 pots; 8 bean seeds; colored plastic in red, black, and white; ruler; water; toothpicks; greenhouse or window that receives full sun; tape; potting soil; pencil; small cup.
- Fill pots with equal amounts of potting soil. Make a hole about 2 cm long in each pot using a pencil, and place 1 seed in each pot.
- Cover seed with loose soil. Mark where you planted the seed with a toothpick.
- Cut plastic in pieces large enough to cover each pot. Cut a smaller hole in the center of the plastic and cover pot with the plastic. Be sure the smaller hole in the center is where your toothpick is so the seed is exposed to light.
- Take the toothpicks out after you have taped the plastic to the pot. Do this twice for each of the colors. You will have 2 red, 2 black, 2 white, and 2 uncovered.
- After the seeds have emerged through the soil (about 5 days), take stem measurements. Measure the stems in each pot for 14 days.
- Do not forget to water your plants during the experiment. About every other day, use a small cup and pour a small amount of water in each hole where the plant is growing. Note the differences in height among the plants grown over different colored plastic.
Results: Which plastic helped produce the longest stem length? Which plant had the shortest stem length? What do you think this tells us about how a plant uses reflected light?
Have you ever put a plant by heater and the plant died or you put a plant in the garage in winter and it never sprouted? Have you ever wondered which temperature a plant grows best in?
This experiment is to find out in which plants grow best.
This report contains information on Seed Germination, Seed Dormancy, Root (botany) and Stems and Leaves.
Germination dose not take place unless the seed is in a good environment the main keys for growing a plant are adequate water and oxygen and also sunlight. Different kinds of plant germinate at different temperatures. Some plants require more sunlight to germinate then others. During germination, water diffuses though the seed coats into the embryo, which has been almost completely dry during the period of dormancy. With the absorption of oxygen by the seed, energy is made available for growth. From the time of germination until the plant is completely independent of food stored in the seed, the plant is known as a seedling.
Seed Dormancy is when a seed has fallen form the parent plant before they are able to germinate. Lack of viability of seed is often confused with seed dormancy. Many seeds require a so-called resting period after the have fallen from there parent plant. In some plants, chemical changes take place during the resting period that make the seed ready for germination. Still other seeds have extremely tough seed coats that must soften or decay before water and oxygen can enter the seed to take part in the growth of the embryo, or before the growing embryo is capable of bursting through the seed coat.
The first root of the plant, known as the radicle, elongates during germination of the seed and forms the primary root. Roots that branch from the primary root are called secondary roots. In many plants the primary root is known as a taproot because it is much larger than secondary roots and penetrates deeper into the soil. Some plants having taproots cannot be transplanted easily, for breaking the taproot may result in the loss of most of the root system and cause the death of the plant.
Stems and Leaves
Stems usually are above ground, grow upward, and bear leaves, which are attached in a regular pattern at nodes along the stem. The portions of the stem between nodes are called internodes. Growing plants give rise to new leaves, which surround and protect the stem tip, before they expand. Stems are more variable in external appearance and internal structure than roots, but they also consist of three tissue systems and have several features in common.
Leaves are the primary photosynthetic organs of most plants. They usually are flattened blades that consist, internally, mostly of parenchyma tissue called the mesophyll, which is made up of loosely arranged cells with spaces between them. The spaces are filled with air, from which the cells absorb carbon dioxide and into they expel oxygen. The leaf blade is connected to the stem though a narrowed portion called the petiole, or stalk, which consists mostly of vascular tissue.
This report explained about seed germination. The term seed germination is applied to the resumption of the growth of the seed embryo after the period of dormancy. This report also talks about seed dormancy, which is when a seed has fallen form the parent plant before they are able to germinate. This report also talks about root (botany). Which tells about the roots of the plants. This report also talks about stems and leaves. Stems are usually above ground, grow upward and bear leaves. Leaves are primary photosynthetic organs of most plants.
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The Effect of Temperature on the Rate of Photosynthesis
Photosynthesis defines the process by which plants and some bacteria manufacture glucose. Scientists summarize the process as follows: using sunlight, carbon dioxide + water = glucose + oxygen. The process occurs within special structures called chloroplasts located in the cells of leaves. Optimum photosynthetic rates lead to the removal of greater amounts of carbon dioxide from the local atmosphere, producing greater amounts of glucose. Since glucose levels within plants are difficult to measure, scientists utilize the amount of carbon dioxide assimilation or its release as a means to measure photosynthetic rates. During the night, for example, or when conditions are not prime, plants release carbon dioxide. Maximum photosynthetic rates vary between plant species, but crops such as maize can achieve carbon dioxide assimilation rates as high as 0.075 ounce per cubic foot per hour, or 100 milligrams per decimeter per hour. To achieve optimum growth of some plants, farmers keep them in greenhouses that regulate conditions such as humidity and temperature. There are three temperature regimes over which the rate of photosynthesis changes.
Prof Andreas Oschlies is head of the marine biogeochemical modelling group and speaker of the Collaborative Research Centre SFB 754 at the Helmholtz Centre for Ocean Research Kiel (GEOMAR) and Kiel University, Prof Peter Brandt is professor of physical oceanography at GEOMAR and Kiel University, and Dr Lothar Stramma and Dr Sunke Schmidtko are senior scientists in the physical oceanography group at GEOMAR.
Direct measurements show the amount of oxygen in the global oceans has decreased by around 2% over the past 50 years.
Climate change is thought to be a principal cause of this “deoxygenation”, affecting how much oxygen seawater can hold and the circulation patterns that carry oxygen-rich water to the deeper ocean.
In a new review paper, published in Nature Geoscience, we assess the scientific literature on the direct and indirect impacts of rising global temperatures on ocean oxygen levels, and the threat this poses to marine life.
Our findings show that climate models underestimate deoxygenation to date, but project that it will continue and accelerate. Improving understanding on the processes involved and expanding data collection will help reduce the uncertainties in models and, hence, produce more robust projections.
Dangers of deoxygenation
At the ocean surface, oxygen is supplied through air-sea gas exchange and from photosynthesising marine plants. For the rest of the oceans, the distribution of oxygen is, therefore, governed by a delicate balance of supply from the surface via circulation and mixing and consumption by marine life through respiration.
Across the global oceans today, there are various pockets with low or no oxygen – including parts of the tropical oceans off California, Peru and Namibia and the subsurface waters of the Arabian Sea.
“Oxygen minimum zones” are a natural phenomenon, caused by the combined action of sluggish ocean circulation and the decomposition of organic matter sinking out of productive surface areas often associated with ocean upwelling regions.
The oxygen levels in these zones are low enough to be lethal to most marine life. Low oxygen regions can also release nitrous oxide (N2O) – a potent greenhouse gas – into the atmosphere.
Research suggests that these low-oxygen regions are expanding, which could have “dramatic” biological, ecological, economic and climatic consequences.
And the risk of deoxygenation is not just limited to these specific zones. Reducing oxygen levels is occurring at all oxygen concentrations in all ocean basins and affects a growing number of coastal regions.
Role of global warming
While the oxygen dissolved in seawater only amounts to around 0.6% of what the atmosphere contains, it is nevertheless essential for all higher forms of marine life. In addition, the respiration of organisms continuously consumes oxygen essentially everywhere in the ocean.
The most recent and comprehensive analysis of oxygen changes in the global oceans suggests there has been an average 2% decline since 1960.
As the maps below indicate, deoxygenation varies considerably across the oceans. They show gains (blue shading) and losses (red) in oxygen in the ocean down to 1,200 metres (upper map) and beyond (lower). The largest declines in oxygen have predominantly occurred along the equator and in the Arctic.
Oxygen change in the ocean. Observational estimate of the 50yr (1960 to 2010) oxygen change in the upper (0-1,200m) and deep (1,200m – sea floor) ocean in micromole per kilogram per decade (µmol/kg/decade). Data are taken from Schmidtko et al. (2017). Lines indicate boundaries of oxygen minimum zones with less than 80 µmol/kg of oxygen anywhere within the water column (dash-dotted), less than 40 µmol/kg (dashed) and less than 20 µmol/kg (solid). Modified from: Oschlies, et al. (2018)
Research shows that human-caused global warming is the principal cause of marine oxygen loss. Humans also play an additional role through the input of nutrients to the oceans in coastal regions, though the individual processes at play are not straightforward to disentangle.
Warming affects the ocean and its dissolved oxygen content in several ways. Among other things, it influences the solubility of oxygen in the water. The warmer the water, the less gas that can dissolve in it.
Until now, this process mainly affected the upper few hundred meters of the oceans, which have been in contact with the atmosphere most recently. This effect explains up to 20% of the total marine oxygen loss so far and about 50% of that in the upper 1,000 metres of the oceans.
In addition, warming alters patterns of global ocean circulation, which affects the mixing of oxygen-rich surface waters with deeper oxygen-poor water. It also changes how quickly organisms metabolise and respire, which affects consumption of marine oxygen.
Finally, there are indirect impacts of warming on upper-ocean nutrient supply and subsequent production and downward export of organic matter available for respiration throughout the ocean.
In general, climate model simulations underestimate the scale of the observed deoxygenation. As the chart below shows, the global models used in the fifth assessment report of the Intergovernmental Panel on Climate Change (IPCC) on average simulate only one third of the 2% decline.
This discrepancy between observational estimates and models needs to be resolved to ensure reliable model projections of deoxygenation into the future.
Simulated evolution of the models of the fifth assessment report of the IPCC with an average 0.6% decline during the 50-year period 1960-2010 (after Bopp et al., 2013). The observational estimate for the period by Schmidtko et al. (2017) amounts to 2%.
While the decreased solubility of oxygen in warming seawater is generally well represented in models, improvements are needed to better capture the other impacts of rising temperatures.
For example, a surprising result of our analysis is the large estimated oxygen loss in regions of the deep ocean below 1200 metres in depth, particularly in the Southern Ocean, the Arctic and the tropical Pacific.
Yet models do generally not reproduce these deep-ocean oxygen changes. Resolving these limitations requires a better understanding of the physical processes involved, which – in turn – means expanding the coverage of direct measurements.
Biogeochemical feedbacks that can lead to accelerated oxygen loss, such as the release of phosphorus and iron from sediments beneath oxygen-free waters, are also not accounted for in most models today and may explain part of why they underestimate the deoxygenation to date.
Finally, improvements are needed to help models describe the complex system of surface and deep currents that supplies oxygen to the deeper ocean.
Ocean oxygen loss is increasingly being recognised as a major threat to marine ecosystems and shifting habitat conditions in many parts of the global ocean.
Deoxygenation feedbacks on climate via the production of potent greenhouse gases such as N2O and methane under low-oxygen conditions become more likely in a warmer climate. Therefore, it is essential to resolve the discrepancy between observations and models, which are ultimately required for reliable projections into the future.
To close these gaps, we recommend more intensive and internationally-coordinated ocean observations. We need multidisciplinary process studies to better understand the delicate balance of oxygenation and oxygen consumption in the dynamically changing oceans.
Research projects like our Kiel-based Collaborative Research Centre SFB 754 Climate-Biogeochemistry Interactions in the Tropical Ocean and international initiatives such as the Global Ocean Oxygen Network are helpful in moving the field forward.
An improvement of the models in terms of the ocean oxygen budget would have another advantage: oxygen is an ideal parameter for calibrating models that calculate the uptake of CO2 by the ocean. Thus, at the same time, we would improve our knowledge of the carbon cycle.
Sharelines from this story
- Guest post: How global warming is causing ocean oxygen levels to fall
- Oxygen levels in the global oceans have dropped 2% in 50 years – and climate change is the main cause
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