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What happens when you take a deciduous tree and place it in a climate controlled greenhouse?

What happens when you take a deciduous tree and place it in a climate controlled greenhouse?


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The greenhouse would have stable level of light, (matched with day/night wavelength brightness changes like outside the greenhouse), humidity and temperature.

Do certain processes in the tree not trigger? Does this harm the organism, and are there changes in life expectancy?


It harms the trees, seasonal chemistry in the plant is reduced and weakened they have tried growing apples and decidious fruit trees at the equator and they have to treat them chemically to help them stay stronger:

http://www.actahort.org/books/49/49_14.htm

the tropics have seasonal queues, and in a greenhouse with no temp and light change, the plant would be very disoriented, the critical glucose and leaf cycling would be very degraded, because plants have most of their queues from temps, water and sun.

http://www.madsci.org/posts/archives/2001-02/981072513.Bt.r.html

more infos


Pine trees one of biggest contributors to air pollution: Pine gases chemically transformed by free radicals

Pine trees are one of the biggest contributors to air pollution. They give off gases that react with airborne chemicals -- many of which are produced by human activity -- creating tiny, invisible particles that muddy the air. New research from a team led by Carnegie Mellon University's Neil Donahue shows that the biogenic particles formed from pine tree emissions are much more chemically interesting and dynamic than previously thought. The study provides the first experimental evidence that such compounds are chemically transformed by free radicals, the same compounds that age our skin, after they are first formed in the atmosphere.

These findings, published in the Proceedings of the National Academy of Sciences, can help make climate and air quality prediction models more accurate, and enable regulatory agencies to make more effective decisions as they consider strategies for improving air quality.

"We have been able to show conclusively that biogenics are chemically transformed in the atmosphere. They're not just static. They keep going, they keep changing and they keep growing," said Donahue, professor of chemistry, chemical engineering, engineering and public policy, and director of Carnegie Mellon's Center for Atmospheric Particle Studies. "Quite a few atmospheric models, which are commonly used to inform research and policy, have been assuming that that doesn't happen. What we really need to have in the models is an accurate representation of what's really going on in the atmosphere, and that's what this lets us do."

The air that we breathe is chock-full of particles called aerosols. These tiny liquid or solid particles come from hundreds of sources including trees, volcanoes, cars, trucks and wood fires. The small particles influence cloud formation and rainfall, and affect climate and human health. In the United States each year, 50,000 premature deaths from heart and lung disease are attributable to excess concentrations of aerosols, especially particles less than 2.5 micrometers in diameter.

"There's a very, very strong body of data that establishes that fine particles in the air we breathe have a significant bad effect on people. What is less well understood is how the size and chemical composition of those particles influences that effect," Donahue said.

What complicates matters is that the atmosphere is a highly oxidizing, highly reactive place, which means that aerosols are transformed very rapidly into particles that can have completely different chemical compositions. Donahue and colleagues in the Center for Atmospheric Particle Studies were the first to describe the chemical processes involving free radicals that transform aerosols emitted by human-made sources like diesel exhaust. But this mechanism didn't explain what happens to natural compounds when they enter the atmosphere.

"It was too aggressive and made too much stuff, so the modelers simply turned off biogenic aging entirely. This seemed a little extreme," Donahue said. He suspected that the biogenic particles would age too, but in a different way.

Donahue, together with colleagues in Germany, Sweden, Denmark and Switzerland, set out to test this hypothesis using fake atmospheres called smog chambers, which contain several cubic meters of air in an enclosed space in the laboratory. They fed alpha-pinene, an aerosol released by pine trees, and ozone into the smog chambers and then added hydroxyl (OH) radicals, which are naturally occurring, highly reactive molecules that drive reactions with other chemicals present in the air. The researchers gathered data from four different smog chambers and fed it into a computer model that they developed. They discovered that OH ages the particles, altering their properties and concentrations and producing three times more particulate matter than what was originally released into the atmosphere.

"The most intriguing part is that humans may influence the way that chemistry plays out," Donahue said. "The trees emit the stuff, but since human activity changes the chemistry taking place in the atmosphere, those changes can affect the amount and properties of the natural aerosols. There is a lot of evidence that, even when organic gases come from natural sources, the aerosol levels that come from them are controlled by human activity. Our work shows one of the ways this can happen."

In addition to Carnegie Mellon, the authors include researchers from the Karlsruhe Institute of Technology, the Forschungszentrum Jülich, and the Johannes Gutenberg University, Germany the University of Gothenberg, Sweden the University of Copenhagen, Denmark and the Paul Scherrer Institute, Switzerland.


What we do Justdiggit

Global warming is moving in fast. Our Earth is drying up.

Our job is to reverse it, and we have one decade. We know that we have to keep the global temperature increase below 2°C , to stop irreversible damage to the planet that sustains us. We need to act together and we need to act fast.

The Place: Africa

In Africa, 3.9 million ha of forests are lost each year, and 65% of land is affected by degradation.

This results in increasing water and food scarcity, poverty, loss of biodiversity. Worldwide, there are 2 billion ha of restorable land. Africa has the largest restoration potential of all continents on our beautiful planet, with the opportunity to protect and bring back biodiversity to some of the world’s most precious ecosystems.

The Solution: Nature

Luckily, we can turn things around!

Applying nature-based solutions to restore vegetation is the key to bringing down rising global temperatures. Plants and trees are the air conditioning of our planet: they remove carbon from the air and cool the surrounding area. Also, regreening and restoring degraded land positively impacts water and food security, biodiversity and creates a better life for millions of people and animals.

What we need to do, is to bring back nature and restore the planet’s balance. That is why we’ve partnered with the United Nations Environmental Programme, who declared 2021-2030 as the Decade on Ecosystem Restoration . Together we can make African land green, lush and cool by 2030.


Types of Stem Cuttings

The four main types of stem cuttings are herbaceous, softwood, semi-hardwood, and hardwood. These terms reflect the growth stage of the stock plant, which is one of the most important factors influencing whether or not cuttings will root. Calendar dates are useful only as guidelines. Refer to Table 1 for more information on the best time to root stem cuttings of particular ornamental plants.

Table 1. Optimum stage of tissue (wood) maturity for rooting stem cuttings of selected woody ornamentals.
Common Name Scientific Name Type of Cutting (SW = softwood, SH = semi-hardwood, HW = hardwood)
Evergreen Plants
Abelia Abelia spp. SH, HW
Arborvitae, American Thuja occidentalis SH, HW
Arborvitae, Oriental Platycladus orientalis SW
Azalea (evergreen & semi-evergreen) Rhododendron spp. SH
Barberry, Mentor Berberis x mentorensis SH
Barberry, Japanese Berberis thunbergii SH, HW
Barberry, wintergreen Berberis julianae SH
Boxwood, littleleaf Buxus microphylla SH, HW
Boxwood, common Buxus sempervirens SH, HW
Camelia Camelia spp. SW, SH, HW
Ceanothus Ceanothus spp. SW, SH, HW
Cedar Cedrus spp. SH, HW
Chamaecyparis False cypress Chamaecyparis spp. SH, HW
Cotoneaster Cotoneaster spp. SW, SH
Cryptomeria, Japanese Cryptomeria japonica SH
Daphne Daphne spp. SH
Elaeagnus, thorny Elaeagnus pungens SH
English ivy Hedera helix SH, HW
Euonymus Euonymus spp. SH
Fir Abies spp. SW, HW
Gardenia Cape jasmine Gardenia jasminoides SW, SH
Heath Erica spp. SW, SH
Hemlock Tsuga spp. SW, SH, HW
Holly, Chinese Ilex cornuta SH, HW
Holly, Foster's Ilex x attenuata 'Fosteri' SH
Holly, American Ilex opaca SH
Holly, Yaupon Ilex vomitoria SH, HW
Holly, English Ilex aquifolium SH
Holly, Japanese Ilex crenata SH, HW
Jasmine Jasminum spp. SH
Juniper, creeping Juniperus horizontalis SH, HW
Juniper, Chinese Juniperus Chinensis SH, HW
Juniper, shore Juniperus conferta SH, HW
Leyland cypress x Cupressocyparis leylandii SH, HW
Magnolia Mahonia spp. SH
Oleander Nerium oleander SH
Osmanthus, holly Osmanthus heterophyllus Sh, HW
Photinia Photinia spp. SH, HW
Pine, Mugo Pinus mugo SH
Pine, Eastern white Pinus strobus HW
Pittosporum Pittosporum spp. SH
Podocarpus Podocarpus spp. SH
Privet Ligustrunum spp. SW, SH, HW
Pyracantha Firethorn Pyracantha spp. SH
Rhododendron Rhododendron spp. SH, HW
Spruce Picea spp. SW, HW
Viburnum Viburnum spp. SW, HW
Yew Taxus spp. SH, HW
Common Name Scientific Name Type of Cutting (SW = softwood, SH = semi-hardwood, HW = hardwood)
Deciduous Trees
Azalea (deciduous) Rhododendron spp. SW
Basswood American linden Tilia americana SW
Birch Betula spp. SW
Bittersweet Celastrus spp. SW, SH, HW
Blueberry Vaccinium spp. SW, HW
Broom Cytisus spp. SW, HW
Callery pear Pyrus calleryana SH
Catalpa Catalpa spp. SW
Clematis Clematis spp. SW, SH
Crabapple Malus app. SW, SH
Crape myrtle Lagerstroemia indica SH
Cherry, flowering Prunus spp. SW, SH
Dawn redwood Metasequoia glyptostroboides SW, SH
Deutzia Deutzia spp. SW, HW
Dogwood Cornus spp. SW, SH
Elderberry Sambucus spp. SW
Elm Ulmus spp. SW
Euonymus Euonymus spp. HW
Forsythia Forsythia spp. SW, SH, HW
Fringe tree Chioanthus spp. SW
Ginkgo, Maidenhair tree Ginkgo biloba SW
Goldenrain tree Koelreuteria spp. SW
Hibiscus, Chinese Hibiscus rosa-sinensis SW, SH
Honey locust Gleditsia triacanthos HW
Honeysuckle Lonicera spp. SW, HW
Hydrangea Hydrangea spp. SW, HW
Ivy, Boston Parthenocussus tricuspidata SW, HW
Larch Larix spp. SW
Lilac Syringa spp. SW
Maple Acer spp. SW, SH
Mock orange Philadelphus spp. SW, HW
Mulberry Morus spp. SW
Poplar Aspen Cottonwood Populus spp. SW, HW
Poplar, Yellow Tulip tree Tulip poplar Liriodendron tulipfera SH
Quince, flowering Chaenomeles spp. SH
Redbud Cercis spp. SW
Rose of Sharon Shrub-althea Hibiscus syriacus SW, HW
Rose Rosa spp. SW, SH, HW
Russian olive Elaeagnus angustifolia HW
Serviceberry Amelanchier spp. SW
Smoke tree Cotinus coggygria SW
Spirea Spiraea spp. SW
St. Johnswort Hypericum spp. SW
Sumac Rhus spp. SW
Sweet gum Liquidambar styraciflua SW
Trumpet creeper Campsis spp. SW, SH, HW
Virginia creeper Parthenocissus quinquefolia SW, HW
Weigela Weigela spp. SW, HW
Willow Salix app. SW, SH, HW
Wisteria Wisteria spp. SW

Herbaceous cuttings are made from non-woody, herbaceous plants such as coleus, chrysanthemums, and dahlia. A 3- to 5-inch piece of stem is cut from the parent plant. The leaves on the lower one-third to one-half of the stem are removed. A high percentage of the cuttings root, and they do so quickly.

Softwood cuttings are prepared from soft, succulent, new growth of woody plants, just as it begins to harden (mature). Shoots are suitable for making softwood cuttings when they can be snapped easily when bent and when they still have a gradation of leaf size (oldest leaves are mature while newest leaves are still small). For most woody plants, this stage occurs in May, June, or July. The soft shoots are quite tender, and extra care must be taken to keep them from drying out. The extra effort pays off, because they root quickly.

Semi-hardwood cuttings are usually prepared from partially mature wood of the current season&rsquos growth, just after a flush of growth. This type of cutting normally is made from mid-July to early fall. The wood is reasonably firm and the leaves of mature size. Many broadleaf evergreen shrubs and some conifers are propagated by this method.

Hardwood cuttings are taken from dormant, mature stems in late fall, winter, or early spring. Plants generally are fully dormant with no obvious signs of active growth. The wood is firm and does not bend easily. Hardwood cuttings are used most often for deciduous shrubs but can be used for many evergreens. Examples of plants propagated at the hardwood stage include forsythia, privet, fig, grape, and spirea.

The three types of hardwood cuttings are straight, mallet, and heel (Figure 3). A straight cutting is the most commonly used stem cutting. Mallet and heel cuttings are used for plants that might otherwise be more difficult to root. For the heel cutting, a small section of older wood is included at the base of the cutting. For the mallet cutting, an entire section of older stem wood is included.

Figure 3. The three types of hardwood cuttings are straight, mallet, and heel.


The facts

Natural climate solutions are at the heart of Conservation International’s work. These are actions that conserve, restore or improve the use or management of ecosystems while maintaining their capacity to absorb and store carbon from the atmosphere. Nature could get us at least 30 percent of the way to solving the climate crisis, while also providing a host of additional benefits — filtering fresh water, providing breathable air — that other approaches to climate change don’t offer.

Even better: Nature can do this today — for free.


Conifers naturally shed needles in summer and fall

CORVALLIS, Ore. – Watching trees turn bewitching shades of orange, red and yellow is part of the magic of autumn, but seeing the needles on conifers fade to yellow and fall to the ground can be unnerving.

Such botanical behavior is natural, said Paul Ries, urban forestry specialist for the Oregon State University Extension Service. Evergreen conifers shed needles just as deciduous trees lose leaves it just happens over a longer period of time.

“The difference is that with deciduous trees they do it all at once in a shorter time span,” he said. “Evergreen conifers shed needles from summer through fall. And those that fall are only a fraction of the total needles.”

Depending on the species, it can take anywhere from two to seven years for a conifer to lose and grow all its needles.

“When you look at a conifer, yes, it’s technically evergreen because it’s always green,” Ries said. “But you’re not looking at the same needles all the time. They shed the oldest needles every year. People think they’re not in good health. But in reality they’re just going through the normal cycle.”

The outermost needles are the newest, so those dropping are in the interior and less likely to be noticed. If other areas of the tree are turning yellow, then it’s time to get advice from your local Extension office or a certified arborist. In the past two years, large numbers of Oregonians have watched some of their conifers – largely Douglas-firs – turn brown and sometimes die. That damage, Ries said, is the result of drought and also a problem that should be referred to experts.

A few conifers do lose all their needles in one year, namely western larch (Larix occidentalis), dawn redwood (Metasequoia glyptostroboides) and bald cypress (Taxodium distichum). So if you see one of these trees without needles in winter, no need to worry.

If all this talk about conifers is making you feel like adding one to your landscape, fall is a fine time to plant one. Fall and winter rains will keep the tree watered and give it a good start. But before you take a trip to the nursery and plunk down your money, Ries said to do some homework first and choose the right tree for the right place.

“One call I often get is from people worrying about trees too close to the foundation of their house,” he said. “The rule of thumb is if you have a small tree like a vine maple or Japanese maple, it’s OK close to the house. A large-growing tree like an oak should be at least 20 feet from the foundation.”

Get help choosing a tree, with Extension’s free app designed for iOS and Android tablets called Selecting, Planting and Caring for a New Tree, co-authored by Ries. A downloadable publication is available for those without tablets.


What happens when you take a deciduous tree and place it in a climate controlled greenhouse? - Biology

"Ecological succession" is the observed process of change in the species structure of an ecological community over time. Within any community some species may become less abundant over some time interval, or they may even vanish from the ecosystem altogether. Similarly, over some time interval, other species within the community may become more abundant, or new species may even invade into the community from adjacent ecosystems. This observed change over time in what is living in a particular ecosystem is "ecological succession".

Why does "ecological succession" occur?

Every species has a set of environmental conditions under which it will grow and reproduce most optimally. In a given ecosystem, and under that ecosystem's set of environmental conditions, those species that can grow the most efficiently and produce the most viable offspring will become the most abundant organisms. As long as the ecosystem's set of environmental conditions remains constant, those species optimally adapted to those conditions will flourish. The "engine" of succession, the cause of ecosystem change, is the impact of established species have upon their own environments. A consequence of living is the sometimes subtle and sometimes overt alteration of one's own environment. The original environment may have been optimal for the first species of plant or animal, but the newly altered environment is often optimal for some other species of plant or animal. Under the changed conditions of the environment, the previously dominant species may fail and another species may become ascendant.

Ecological succession may also occur when the conditions of an environment suddenly and drastically change. A forest fires, wind storms, and human activities like agriculture all greatly alter the conditions of an environment. These massive forces may also destroy species and thus alter the dynamics of the ecological community triggering a scramble for dominance among the species still present.

Are there examples of "ecological succession" on the Nature Trail?

Succession is one of the major themes of our Nature Trail. It is possible to observe both the on-going process of succession and the consequences of past succession events at almost any point along the trail. The rise and the decline of numerous species within our various communities illustrates both of the types of motive forces of succession: the impact of an established species to change a site's environmental conditions, and the impact of large external forces to suddenly alter the environmental nature of a site. Both of these forces necessarily select for new species to become ascendant and possibly dominant within the ecosystem.

Some specific examples of observable succession include:
1. The growth of hardwood trees (including ash, poplar and oak) within the red pine planting area. The consequence of this hardwood tree growth is the increased shading and subsequent mortality of the sun loving red pines by the shade tolerant hardwood seedlings. The shaded forest floor conditions generated by the pines prohibits the growth of sun-loving pine seedlings and allows the growth of the hardwoods. The consequence of the growth of the hardwoods is the decline and senescence of the pine forest. (Observe the dead pine trees that have fallen. Observe the young hardwoods growing up beneath the still living pines).
2. The raspberry thickets growing in the sun lit forest sections beneath the gaps in the canopy generated by wind-thrown trees. Raspberry plants require sunlight to grow and thrive. Beneath the dense shade canopy particularly of the red pines but also beneath the dense stands of oaks, there is not sufficient sunlight for the raspberry's survival. However, in any place in which there has been a tree fall the raspberry canes have proliferated into dense thickets. You may observe this successional consequence of macro-ecosystem change within the red pine stand and all along the more open sections of the trail. Within these raspberry thickets, by the way, are dense growths of hardwood seedlings. The raspberry plants are generating a protected "nursery" for these seedlings and are preventing a major browser of tree seedlings (the white tailed deer) from eating and destroying the young trees. By providing these trees a shaded haven in which to grow the raspberry plants are setting up the future tree canopy which will extensively shade the future forest floor and consequently prevent the future growth of more raspberry plants!
3. The succession "garden" plot. This plot was established in April, 2000 (please see the series of photographs on the "Succession Garden Plot" page). The initial plant community that was established within the boundaries of this plot was made up of those species that could tolerate the periodic mowing that "controlled" this "grass" ecosystem. Soon, though, other plant species became established as a consequence of the removal of the stress of mowing. Over time, the increased shading of the soil surface and the increased moisture retention of the undisturbed soil-litter interface allowed an even greater diversity of plants to grow and thrive in the Succession Garden. Eventually, taller, woody plants became established which shaded out the sun-loving weed community. In the coming years we expect tree seedlings to grow up within the Succession Garden and slowly establish a new section of the forest.

How are humans affected by ecological succession?

Ecological succession is a force of nature. Ecosystems, because of the internal species dynamics and external forces mentioned above, are in a constant process of change and re-structuring. To appreciate how ecological succession affects humans and also to begin to appreciate the incredible time and monetary cost of ecological succession, one only has to visualize a freshly tilled garden plot. Clearing the land for the garden and preparing the soil for planting represents a major external event that radically re-structures and disrupts a previously stabilized ecosystem. The disturbed ecosystem will immediately begin a process of ecological succession. Plant species adapted to the sunny conditions and the broken soil will rapidly invade the site and will become quickly and densely established. These invading plants are what we call "weeds". Now "weeds" have very important ecological roles and functions (see, for example, the "Winter Birds" discussion), but weeds also compete with the garden plants for nutrients, water and physical space. If left unattended, a garden will quickly become a weed patch in which the weakly competitive garden plants are choked out and destroyed by the robustly productive weeds. A gardener's only course of action is to spend a great deal of time and energy weeding the garden. This energy input is directly proportional to the "energy" inherent in the force of ecological succession. If you extrapolate this very small scale scenario to all of the agricultural fields and systems on Earth and visualize all of the activities of all of the farmers and gardeners who are growing our foods, you begin to get an idea of the immense cost in terms of time, fuel, herbicides and pesticides that humans pay every growing season because of the force of ecological succession.

Does ecological succession ever stop?

There is a concept in ecological succession called the "climax" community. The climax community represents a stable end product of the successional sequence. In the climate and landscape region of the Nature Trail, this climax community is the "Oak-Poplar Forest" subdivision of the Deciduous Forest Biome. An established Oak-Poplar Forest will maintain itself for a very long period of time. Its apparent species structure and composition will not appreciably change over observable time. To this degree, we could say that ecological succession has "stopped". We must recognize, however, that any ecosystem, no matter how inherently stable and persistent, could be subject to massive external disruptive forces (like fires and storms) that could re-set and re-trigger the successional process. As long as these random and potentially catastrophic events are possible, it is not absolutely accurate to say that succession has stopped. Also, over long periods of time ("geological time") the climate conditions and other fundamental aspects of an ecosystem change. These geological time scale changes are not observable in our "ecological" time, but their fundamental existence and historical reality cannot be disputed. No ecosystem, then, has existed or will exist unchanged or unchanging over a geological time scale.

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Trees and Carbon Dioxide: What Is the True Connection?

It’s not hard to find wacky ideas about science on the internet — bizarre concepts that stand out because they are so far removed from reality. However, when popular ideas about science are very nearly correct — but not quite — such subtle errors can be hard to spot. A fascinating example involves our popular explanations for the relationship between trees and carbon dioxide. It’s not that these popular explanations are completely wrong — in fact they are mostly correct — and yet the limitations of some of these models can lead to erroneous conclusions.

Below are six common mental models that we often use to explain the connection between trees and carbon dioxide. Many of us have been exposed to more than one of these concepts, although we might rely on a single model as our principal mental framework for the topic. All six of these models can be found in educational materials and on the internet. As we examine these six ideas, it may be useful for you to consider which model most closely aligns with what you have been taught.

The common thread among these models is that “trees absorb carbon dioxide”. This concept has recently grown quite popular — because forests help offset some of the human-caused increase in atmospheric carbon dioxide. In other words, there is a connection between forests — especially tropical rainforests — and global climate change. If we can slow down or reverse the worldwide reduction in the number of trees, then this will help to slow the increase in atmospheric CO2. But what does it really mean when we say “trees absorb carbon dioxide”? Each of the six mental models provides a concise — but different — explanation of what this phrase means.

By using the term “mental model”, we can focus on what happens in the mind of a person who learns and interprets a concept. This mental model might not exactly match what the author of the learning material had intended — in part because the learner is likely to “connect the dots”, drawing conclusions that are not explicitly stated in the learning material.

The first three models listed below are the simplest — which makes them quite popular — but they are also the mostly likely to lead to scientific misconceptions. The final three models are better at avoiding such misconceptions, but even these models can be slightly misleading if used in isolation. Therefore the strongest mental framework is a combination of models 4, 5, and 6:

Model 1 — Trees filter carbon dioxide from the air.

This mental model equates trees to an air filtration system, filtering out carbon dioxide and other “bad” substances from the air. Unlike some of the other models, this model offers no explanation as to what happens to the CO2 that has been removed. This can lead to the misconception that the extracted CO2 is completely destroyed. (Note: Any variation of this model that specifically mentions storing carbon dioxide is actually Model 2.)

One advantage of this model is that it is so easy to understand — and it is certainly true that trees remove carbon dioxide from the air, although the mechanism is different from that of a filtration system. However, there are two principal weaknesses to this model:

1) By failing to acknowledge that trees store massive amounts of carbon, this model suggests that the only harm in cutting down trees is that there are fewer trees to filter out carbon dioxide. There is no suggestion that destroying a forest can release huge amounts of carbon dioxide back into the atmosphere.

2) This model avoids the question of “Why do trees do this? What’s in it for the trees?” This oversight sharply limits the value of the model — because answering this question opens the door to several important insights about the relationship between trees and CO2.

Another weakness, common to all of the first three models, is the implication that trees are the only green plants that remove carbon dioxide from the air.

Model 2 — Trees absorb and store carbon dioxide.

This mental model equates a tree to a giant sponge that sops up carbon dioxide from the air. The underlying idea is that trees constantly absorb and store CO2.

Like Model 1, this model is very easy to understand — which is certainly an advantage. A second advantage is the acknowledgment that the carbon dioxide is not magically eliminated. And a third advantage is the implication that carbon dioxide will return to the atmosphere if the tree is destroyed.

Even though Model 2 is better than Model 1, it still has several weaknesses:

1) Like Model 1, this model avoids the question of “Why do trees do this? What’s in it for the trees?” Again this oversight sharply limits the value of the model.

2) It is just plain wrong to say that trees “store carbon dioxide”. Trees use carbon dioxide — they don’t store it. What is true is that a tree contains a large quantity of carbon-based compounds. In other words, a tree converts carbon dioxide into other carbon-based chemical compounds that are useful to the tree. The great mass of a tree consists primarily of just two things: carbon-based compounds (also called organic compounds) and water.

However, a tree does not actually store most of those organic molecules — at least not in the popular sense of the word “store”, which implies that unused material has been set aside for possible later use. On the contrary, most of those molecules have been turned into wood or leaves or other essential parts of the tree.

3) This model implies that any carbon dioxide “absorbed” by the tree remains locked away until the tree dies. (Some educational materials explicitly make this point, even though it is wrong.) In fact there are several mechanisms by which carbon dioxide is returned to the air even while the tree is alive — including the metabolism of sugars by plant cells, and the annual shedding of leaves by deciduous trees.

4) This model ignores the role of other plants in removing carbon dioxide from the air. It’s not just trees that do it! In fact, some non-forest ecosystems — such as peat bogs — are extremely good at removing carbon dioxide from the air.

Despite the weaknesses of this model, a person who learns this model will realize that destroying a forest has two negative effects connected to carbon dioxide. First, there are fewer trees to remove carbon dioxide from the air. And second, destroying a forest tends to release a lot of carbon dioxide into the atmosphere in a short period of time.

Model 3 — Forests are the lungs of the planet.

This mental model equates forests — especially tropical forests — to a set of lungs, allowing the planet to “breathe”. The idea is that a forest “purifies” the air by absorbing carbon dioxide and releasing oxygen. On a literal level, this is the opposite of what lungs actually do. Lungs take in “fresh” air and exhale the “stale” air — partially depleted of oxygen, but enriched in carbon dioxide. However, because the lung model is clearly a metaphor, it is easy to understand that trees do the opposite of what animal lungs do. Thus there is an implied balance between the forests of the world and the animals of the world. In fact, many educational materials contain graphics that illustrate such a balance.

The main strength of this model is its emphasis on gas exchange — the exchange of carbon dioxide and oxygen — which is an important concept. But if a forest has the equivalent of lungs, then where are these lungs? The answer is that most of the gas exchange occurs in the leaves. Pores on the surface of each leaf allow gases to move in and out. During the day, carbon dioxide enters through these pores, and oxygen escapes. This is consistent with the “reverse lungs” concept. But at night the opposite happens — oxygen enters through the pores, and carbon dioxide escapes — a phenomenon that Model 3 does not explain, or even acknowledge.

Despite the helpful emphasis on gas exchange, this model has several weaknesses:

1) Like Models 1 and 2, this model (in its simplest, most common form) avoids the question of “Why do trees do this? What’s in it for the trees?” A child who has been taught this model might answer this question by saying “Because people and animals need oxygen.” This answer confuses a benefit with a reason.

2) Like Model 1, the simplest version of this model fails to acknowledge that trees store massive amounts of carbon. There is no suggestion that cutting down a forest can release a huge amount of carbon dioxide back into the atmosphere.

3) Furthermore, by failing to explain what happens to the carbon, this model can promote the misconception that carbon dioxide is completely eliminated by conversion to oxygen.

4) This model diverts much of the attention away from the reduction of atmospheric carbon dioxide, shifting the attention to the production of oxygen. Indeed, some websites and educational materials suggest that if the world’s forests were to be cut down, then we would soon run out of oxygen to breathe. (“Forests are the lungs of the earth. If we destroy them, we destroy ourselves!”) Destroying the world’s forests would indeed be catastrophic, but it would not result in our suffocating.

5) Like the first two models, this model also undervalues the role of non-forest ecosystems in reducing atmospheric CO2.

Model 4 — Green plants use sunlight to convert CO2 and water into sugar.

This mental model explains the essence of photosynthesis quite succinctly. Unlike the first three models, this model provides a reason that plants remove carbon dioxide from air — to produce sugar. It also explains what happens to the carbon — it becomes part of the sugar (C6H12O6). This model also implies how green plants benefit from the process — they can use the sugar.

This model usually mentions that oxygen is given off as a waste product of photosynthesis. CO2 and water contain more oxygen atoms than are needed to make sugar, so the excess oxygen is released as a gas. That’s the reason that green plants give off oxygen — not because animals and humans need it. In fact, when early green plants began to pump oxygen into the atmosphere, the gas poisoned much of the existing life on earth — killing it off, but paving the way for the later evolution of oxygen-dependent creatures.

This simple mental model of photosynthesis — that green plants use sunlight to convert CO2 and water into sugar — provides a great foundation for understanding the relationship between trees and carbon dioxide. However, this model is incomplete without a second mental model that explains what happens to all that sugar. The simplest such model (although incomplete) is that the sugar produced by photosynthesis serves as food for the plant. This is a crucial concept. Every living cell needs energy to survive — and for most plant and animals cells, this energy is delivered as sugar. Therefore the sugar produced in the leaves of a plant must be transported to all the living cells in the plant — particularly the roots.

Once you fully grasp these two ideas — that every plant cell needs food in the form of sugar, and that a living plant must move sugar to where it is needed — it makes perfect sense that most land-based green plants have an internal water-based transport system. In fact there are two distinct transport systems. One system moves sugar water down from the leaves to the roots, and the other system moves mineral water up from the roots to the leaves.

So why do plant cells need energy? Cells use the chemical energy of sugar to drive the normal metabolic processes that keep the plant alive. When the cells use this energy, the sugar reverts to carbon dioxide and water — although oxygen is also consumed in the process.

The upshot is that every cell in a plant constantly consumes oxygen and gives off carbon dioxide — just as animal cells do. However, when the sun is shining, the chloroplasts in the leaves and other green surfaces do just the opposite — and they do it at a much faster rate. Thus, during the day, green plants are net consumers of carbon dioxide and net producers of oxygen. But at night, when photosynthesis shuts down, it is just the opposite.

Model 4 is therefore a powerful concept that is closely connected to several important details. But even if you remember all of these details, there is a crucial concept that is missing — the key concept underlying Model 5.

Model 5 — Green plants create biomass animals and decomposers break it down.

The concept missing from Model 4 is that much of the sugar produced by green plants is not used to provide energy to the cells of the plant. Instead, the sugar is converted into other organic compounds that are useful to the plant. A surprisingly wide range of compounds are produced, including starches, fats, proteins, and many other classes of molecules. Some of these compounds, such as starches and fats, require nothing more than the atoms already present in sugar — carbon, hydrogen, and oxygen. But some compounds (such as proteins) require additional atoms (such as nitrogen) that arrive via the mineral water sent up from the roots. This wide range of molecules serves many different purposes in the life of a plant.

However, a very high percentage of the sugar is simply converted into cellulose — or in the case of woody plants, cellulose and lignin. These are the structural materials that give a plant its shape and allow it to stand upright. (Lignin, which is much stiffer than cellulose, is the compound that makes woody plants “woody”.) Therefore the dry mass of a woody plant is composed primarily of cellulose and lignin, and the dry mass of an herbaceous (non-woody) plant is usually composed primarily of cellulose. Humans cannot digest cellulose or lignin, so we tend to eat the parts of plants where the digestible compounds — such as sugars, starches, fats, and proteins — have been concentrated.

Biomass is any material that consists either of living tissue, or tissue that had once been living. In a forest ecosystem, most of the biomass consists of living trees or dead remnants of trees, such as the leaf litter on the forest floor. Some of the biomass is underground, including tree roots, fungus, other microorganisms, and the myriad little critters that live in the soil.

One component of biomass is water — embedded in living or dead tissue. But the rest of the biomass consists almost entirely of energy-rich carbon-based compounds. For that reason, dried biomass is flammable, and can be used as fuel. The most obvious example is firewood, but any dried plant material tends to burn easily. This fact reveals a key detail: that cellulose and lignin contain a lot of stored chemical energy. This energy was originally captured from sunlight and stored in sugar molecules that were later converted to other high-energy molecules. In fact, all the carbon-based compounds in a plant are high-energy, and this energy can be traced back to sugar created by photosynthesis.

The upshot is that green plants are the only organisms that can create biomass — because these are the only organisms that can use the energy of sunlight to manufacture sugar. (There is a minor exception for organisms that use the chemical energy of deep-sea hydrothermal vents.) Animals, like plants, can convert certain high-energy compounds into other high-energy compounds, but in doing so there is always a loss in biomass. In other words, when an animal eats biomass — plant or animal tissue — a small part of that biomass is often incorporated into the body of the animal, becoming muscle or other tissue. But a larger part of that biomass is simply metabolized for its energy. And a far larger part of the eaten biomass is wasted — especially if the animal is incapable of digesting cellulose. The key point here is that in a typical ecosystem, such as a forest or grassland, all of the biomass is originally created by plants.

When discussing the biomass of an ecosystem, it is helpful to consider how dense the biomass is. This can be expressed, for example, as tons of biomass per acre (or in metric tons per hectare). Not surprisingly, forests tend to have the densest biomass figures — especially tropical forests — because so much biomass is locked up in woody tree trunks, branches, and roots.

Model 6 — The forests of the world are a huge carbon sink.

Because all biomass consists of carbon-rich compounds — and the carbon in these compounds originated as atmospheric CO2 captured by green plants to create sugar — forests can be viewed as a major carbon sink. A “carbon sink” is anything that absorbs large amounts of carbon dioxide from the atmosphere, retaining the carbon in one form or another.

Of course, this is a two-way street — because carbon can move in either direction. The biomass of a forest becomes CO2 again whenever any of the following processes occur:

  • Sugars are metabolized by plant or animal cells in order to access the stored energy.
  • Dead biomass, such as fallen leaves or downed trees, decomposes into simpler compounds. (Decomposer organisms play a key role, consuming some of the stored energy while breaking down the organic compounds.)
  • Fire races through a forest, burning the dead forest litter — and in the case of a crown fire, then also consuming parts of living trees.

In a typical forest, far more carbon is captured than is released — although the amount varies according to the type of forest, the age of the forest, and other factors.

Because trees can be very large, it seems intuitive that a forest would store more carbon per acre than any other type of ecosystem. But is that really true? If you only consider the above-ground storage of carbon, then the tropical rainforests of the world are the clear winners in terms of carbon mass. Forests in temperate climates also store a lot of carbon, but less than tropical forests.

However, if you consider the organic carbon stored in soils, then the picture becomes more complicated. There are extensive areas of peatlands in the world, where the density of carbon storage is as great as in tropical forests. However, much of this carbon is stored in a thick blanket of peaty soil, not in living vegetation. The acidic, waterlogged soils prevent fallen organic matter from decomposing, so it builds up over a long period of time. Peatlands are especially common in the far north — such as Canada, Russia, Scandinavia, and Alaska — but the tropics also contain significant areas of peatland.

Destroying peat bogs is as bad as destroying tropical forests, when viewed through the lens of preserving our major carbon sinks. Peat bogs are easily destroyed by draining away the water, which exposes the soil to air, allowing the organic matter to decompose. However, peatlands are not the only ecosystem with high levels of organic carbon in the soil — other examples include grasslands and mangrove swamps. In fact, worldwide there is more organic carbon in the top meter of soil than in all the above-ground biomass, including tropical forests.

Despite the crucial role of vegetation and soil as carbon sinks, they are not the only carbon sinks in the world. The ocean is also a major carbon sink, because carbon dioxide is soluble in water. In fact, there is far more carbon dioxide dissolved in the ocean than there is floating in the atmosphere. Therefore vegetation, soil, and oceans are the three major carbon sinks — but each is capable of returning carbon dioxide to the atmosphere, depending upon current conditions.

To round out this picture, it is also helpful to think about the former carbon sinks of the world, now locked away deep in the earth. There are two such former sinks:

1) Our fossil fuel reserves — oil, gas, and coal — are the remnants of ancient swamps in which large amounts of plant material accumulated without decomposing. This organic matter eventually became buried under deep layers of soil, which hardened into rock. This pool of carbon has been locked away for hundreds of millions of years — but now humans actively seek out these reserves to burn them as fuel, returning the carbon dioxide to the air.

2) The vast amounts of limestone in the earth’s crust are a result of carbon dioxide dissolving in the oceans. CO2 combines with water to form carbonate, which remains dissolved in the water. Many forms of sea life extract carbonate to produce shells, reefs, and other hard structures. Additional carbonate interacts with calcium that has weathered from continental rocks and washed into the ocean. Both of these processes result in a steady rain of calcium carbonate settling to the bottom of the ocean, forming thick layers of marl that eventually become limestone and related rocks. When limestone is processed to create cement, some of the carbon dioxide returns to the air.

We have now examined six popular mental models that attempt to explain the relationship between trees and carbon dioxide — each model consistent with the basic concept that trees remove carbon dioxide from the air:

1. Trees filter carbon dioxide from the air.

2. Trees absorb and store carbon dioxide.

3. Forests are the lungs of the planet.

4. Green plants use sunlight to convert CO2 and water into sugar.

5. Green plants create biomass animals and decomposers break it down.

6. The forests of the world are a huge carbon sink.

Each of these mental models can help the learner to draw useful insights. However, the first three models all have serious weaknesses — including a failure to address the reason that plants absorb carbon dioxide, and a tendency to produce scientific misconceptions. The final three models are far stronger, but each in isolation only paints part of the complete picture. When combined, these last three models can provide a powerful understanding of the relationship between trees and carbon dioxide.

Of course, the forests of the world provide far more benefits than just capturing carbon — and the wholesale destruction of forests does far more harm than just releasing carbon dioxide into the atmosphere. But with the current emphasis on trees as part of the solution for fighting the rising levels of atmospheric carbon dioxide, it is helpful to have a good understanding of the underlying scientific concepts.


Perhaps unsurprisingly grasslands do not store anywhere near as much carbon in their biomass as trees, due to much smaller size above and below ground. However, soils in grassland habitats are very important carbon sinks.

In total, grasslands store 343 gigatons of carbon in the vegetation and top one metre of soil. Sequestering an average of 0.5 gigatons per year. (5)

As with forests, the potential of a grassland to store carbon varies. In general the amount of carbon a grassland can store increases when there is a greater mix of different species. (6)

The majority of grasslands are used for grazing livestock such as cows or sheep (20 million km 2 ). The intensity at which this grazing is carried out affects how much carbon is stored in the soils. Lowering the amount of livestock on a grassland has been found to increase the amount of carbon sequestered.

Condition of the grasslands is also important, if grasslands become degraded they can start to lose carbon. In the past 30 years approximately 3.02 gigatons of carbon has been lost from grassland soils, either through degradation or land use change. (6)

The ability of a grassland soil to absorb carbon also depends on the microbial activity. Higher microbial activity leads to more carbon being absorbed. It can take a long time to restore this balance in the soil when converting other habitats such as arable cropland to grassland. (7)

This has led some authors to question the merit of converting croplands to grassland as a way of storing carbon and tackling climate change. (8) Studies have shown that this only alters the top section of the soils in the short to medium term. Especially if the new grassland is grazed with animals such as cattle which have other negative impacts on the environment such as methane emissions and fertilizer use.


CONCLUSION

Whew. Congratulations, you made it.

You now know that you basically have two options when growing trees from seed: The natural way, which often includes sowing the seeds in the autumn, or through “assisted” germination, which is initially done indoors.

Of course, the easiest way is just to sow outdoors in autumn and let nature take its course, but if you want to be serious about growing your trees, you’ll need to be familiar with both ways.

Once you plant your seedlings on your site, you start the development of fruiting plants ideally suited to your local area. This is a lifetime of work, but with great personal rewards.

If you have more questions, comments or feedback about how to grow trees from seeds, I would like to hear them.


Watch the video: Πέριβάλλον και Μέλλον - Μία ιστορία για την κλιματική αλλαγή (July 2022).


Comments:

  1. Forrest

    Should you tell it - a lie.

  2. Avshalom

    Rather amusing phrase

  3. Verney

    Question is, excellent communication

  4. Skelton

    well, nicho so ... well.



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