Photo credit: Eco Business
Researchers have established that extreme heat can alter the atmospheric chemistry unfavourably for plants, and certainly reduce crop yields. Image: Shutterstock
Plants’ heat response means fiercer heatwaves
Asia faces more extreme heat by mid-century as some plant species react unexpectedly to rising average temperatures, new research shows.
Tomorrow’s heat waves could be even hotter than climate scientists have so far predicted. Maximum temperatures across the Asian continent from Europe to China could be 3°C to 5°C higher than previous estimates – because the forests and grasslands will respond in a different way.
Australian scientists report in the journal Scientific Reports that they looked at the forecasts made by the Intergovernmental Panel on Climate Change under the notorious “business-as-usual” scenario, in which the world’s nations go on burning ever more fossil fuels, to release ever more greenhouse gases.
The average global temperatures will rise steadily – but this rise will be accompanied by ever greater and more frequent extremes of heat.
But then Jatin Kala of Murdoch University in Perth, Western Australia, and colleagues factored in the responses of the plants to rising temperatures.
They looked at data from 314 species of plant from 54 research field sites. In particular, they investigated stomatas, tiny pores on the leaves through which plants absorb carbon dioxide and shed water to the atmosphere.
Read the full story: Eco Business
Research finds water loss from plants a factor in heatwaves
by Tim Howard
WATER loss from vegetation could play a key role in the intensity of heatwaves around the world Australian researchers have found.
The research, published in Nature Scientific Reports, investigated why the projected temperature increases are more than half the change forecast by the IPCC under the business-as-usual model.
“We often underestimate the role of vegetation in extreme temperature events as it has not been included in enough detail in climate models up until this point,” said lead author Dr Jatin Kala from Murdoch University.
“These more detailed results are confronting but they help explain why many climate models have consistently underestimated the increase in the intensity of heatwaves and the rise in maximum temperatures when compared to observations.”
The research predicts heatwaves from Europe to China are likely to be more intense and result in maximum temperatures that are 3°C to 5°C warmer than previously estimated by the middle of the century – all because of the way plants on the ground respond to carbon dioxide in the atmosphere.
The biggest temperature changes were projected to occur over needleleaf forests, tundra and agricultural land used to grow crops.
To get their results the researchers looked at data from 314 plant species across 56 field sites. In particular, they investigated stomata, small pores on plant leaves that take in carbon dioxide and lose water to the atmosphere.
Previously, most climate models assumed all plants trade water for carbon in the exactly same way, ignoring experimental evidence showing considerable variation among plant types. By not accounting for these differences, models have likely over-estimated the amount of water lost to the atmosphere in some regions.
If plants release less water there is more warming and a consequent increase in heat wave intensity.
The study is unique because, for the first time, it used the best available observations to characterise different plants water-use strategies within a global climate model.
Read the full article: Daily Examiner
Heatwave surprise: Plants’ response will make events more intense than thought
Heatwaves in the northern hemisphere may become as much as 5 degrees warmer than previously estimated by mid-century because plants’ response to higher carbon dioxide levels has been miscalculated, according to new research by Australian scientists.
As atmospheric levels of the greenhouse gas increase, plant stomata – the tiny pores on leaves that open to take in CO2 and let out water vapour – won’t need to open as much.
“There’s less water vapour being lost so you have a net warming effect,” said Jatin Kala, a lecturer from Murdoch University and lead author of the paper that was published Monday inNature Scientific Reports.
“During a heatwave, it makes it a lot worse” not to have that evaporative cooling effect, he said.
The researchers used data from 314 plant species across 56 field sites to examine how plants responded. Existing climate models had assumed all plants would trade water for carbon in exactly the same way.
Needle-leaf forests, tundra and agricultural land used for crops would likely suffer the biggest temperature increases. Heatwaves from Europe to China were likely to become 3-5 degrees hotter than the already higher base expected from global warming, Dr Kala said.
Read the full article: Sydney Morning Herald
Photo credit: Google
Study of leaf pores may help scientists predict climate
by Auckland University (2015)
in Scoop Sci-Tech
A major global research project to help build better climate models is using data collected from plants at 56 sites around the world including kauri trees at Auckland’s Waitakere Ranges.
Data for the project was crowd-sourced from scientists in 15 countries. Samples were taken from the leaf pores – or stomata – of 314 plant species in different regions of the globe, from wild Arctic tundra to tropical rain forests.
Leaf pores of plants are highly responsive to environmental conditions such as humidity and soil moisture. Plants use stomata to control water loss and the intake of carbon during photosynthesis.
Because plants trade water for carbon, the data is important to understanding the carbon and water exchange between plants and the atmosphere. These water and carbon cycles are fundamental to a better understanding of how the Earth’s climate might be changing.
School of Biological Sciences lecturer Dr Cate Macinnis-Ng, who took part in the study, says it was good to see New Zealand data being included in the project.
“We contributed data from kauri trees growing in the Waitakere Ranges and it’s fantastic to see New Zealand being included is such a big global project,” she says.
“We sometimes get left out because of our small size. But so many of New Zealand’s plants are found nowhere else so it’s important our ecosystems are represented in climate models.”
Overall the study found that plants use water wisely, indicating that plants have adapted their water-use strategies to their environments.
Global Warming and Stomatal Complex Types
by Abdulrahaman A. A., Oladele F. A. (2008)
in Ethnobotanical Leaflets 12: 553-556. 2008.
In relation with this, plants that possessed stomata with many subsidiary cells (e.g. tetracytic and anomocytic types) will play an important role in reducing greenhouse gases especially carbondioxide. To proof this fact, Obiremi and Oladele (2001) and Oyeleke et al (2004) studied the relationship between the stomatal complex types and transpiration rate in some selected Citrus species and some afforestation tree species respectively.
In both studies, stomatal complex types with many subsidiary cells transpired higher than those with less number. This translates to mean that the latter opens faster to allow carbon dioxide to enter the leaves and water vapour to escape to the atmosphere via the stomatal openings than the former. More over the other aspect of stomatal opening that favour water loss to the atmosphere (i.e. encouraging high rate of transpiration) is also advantageous by humidifying the atmospheric air.
However, to achieve reasonable atmospheric purification, plants with hypostomatic nature of the leaves (i.e. stomata being found or located on the abaxial surface only), lower frequency of stomata with many subsidiary cells (e.g. anisocytic, tetracytic and anomocytic), higher frequency of stomata with frequency of stomata with little subsidiary cells (e.g. cyclic, paracytic and diacytic), less heterogeneous composition of stomatal complex types, less stomatal density and index (i.e. less distribution of stomata on the surface of leaves), and lastly, probably occurrence of trichome (Figures 9 – 11) may be more suitable for afforestation in dry locations. Plants with opposite conditions of the above stomatal features may be more suitable for afforestation in wet environments. These conditions had earlier identified by Oyeleke et al. (2004) and AbdulRahaman and Oladele (2003; 2004).
Read the full story: Ethnobotanical Leaflets
Photo credit: Ethnoleaflets
Stomata of Amaranthus
Global Warming and Stomatal Complex Types
by Abdulrahaman A. A., Oladele F. A. (2008)
in Ethnobotanical Leaflets 12: 553-56. 2008
World leaders, public health specialists, engineers, atmospheric chemists, hydrologists, quantum physicists, mathematicians, botanists, zoologists, have all being striving to stop further release of more greenhouse gases into the atmosphere, and in the occurrence of these gases, they are trying to purifying or cleansing them. One of the cleaners or purifiers that can be employed is stomata. Figures 1 to 8 showed different types of stomatal complex systems in some species of Amaranthus. Stomata are microscopic openings or pores located majorly on the abaxial or lower, and adaxial or upper surfaces of leaves of plants. Though sometimes, stomata are present on the stems, petioles and sepals but in very small number.
Meanwhile, plants have the ability to absorb carbondioxide for carbonxylation and subsequently for production of carbohydrates (especially by the tuberous plants) and for production of woods and fibres (by trees) through photosynthesis. Photosynthesis is the major process by which plants produced carbohydrates, and the major ingredient in this process is carbondioxide. Unfortunately, carbondioxide is one of the greenhouse gases (other examples include methane [CH4], nitrous oxide [N2O], fluorinated gases – hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride). The accumulation of these gases in the atmosphere strengthened the greenhouse effect, which occurs when the heat produced by the sun’s rays entering the atmosphere is retained, causing global warming. Some greenhouse gases such as carbondioxide occur naturally and are emitted to the atmosphere through natural processes and human activities. Other greenhouse gases (e.g. fluorinated gases) are created and emitted solely through human activities. About 99% carbondioxide used in photosynthesis is absorbed through stomata (lenticels and cuticles also absorb carbondioxide to lesser extent). Earlier studies by Carr and Carr (1990), Obiremi and Oladele (2001) and Oyeleke et al. (2004) had confirmed that the more the subsidiary cells surrounding the guard cells, the faster the opening of the stoma (i.e. pore between the two guard cells) and vice versa.
Read the full article: Ethnoleaflets