Author: whimit13

Mitchell white
5/30/2018
Plants in motion

Hypothesis: Air pollution causes serious effects on plants therefore a plants stomatal density should be lower on plants that are subjected to air pollution because of the abundance of CO2 in its surroundings.

The purpose of this research project is to find the effects of every day pollutants. In our case we recorded data on cars and tobacco smoke and their influence on the plants around us. In our first experiment I studied the effects of car pollution on the Mahonia nervosa, better known as the Dull Oregon grape. I had taken six plant samples from the Evergreen State College parking lot C and six plant samples from the forest near the campus. My research partner studied the effects of tobacco smoke on plants and he took twelve from the smoking section and six from the forest. In order for us to see the effects we performed a simple lab to test the stomatal density of each plant. This was done by taking clear nail polish and covering the underside of the leaf. Once the nail polish had finished drying we took a large clear piece of tape and stuck it to the dry nail polish and peeled it off the plant leaving a clear imprint of the underside of the leaf. We then put each one of the samples under the microscope and counted the number of stomata in the field of view under the (400X) magnification and then we calculated the number of stomata per mm2. (Here is a quick video on how to do this for yourself https://youtu.be/fuYdzgSjZqg). As my hypothesis states I predict that the forest samples will have more stomata per leaf due to the findings of Josep Penuelas and Roser Matamala the authors of the Journal of Experimental Botany https://doi.org/10.1093/jxb/41.9.1119 their findings proved that plants that are exposed to more CO2 have s fewer stomatal density. A link my original word document that contains all the photos and graphs in a more organized format (view in print layout format not read mode). Stomatal Density project mitchell white

Samples from parking lot C at the Evergreen State College near the motorbike area were collected. These plants had been subjected to car and motorbike emissions on a daily basis. We also took samples from the designated smoking area on campus and then we took a control plant from the forest in between the organic garden and the college campus all three of which were taken from a shaded area at roughly the same altitude. We tested the stomatal density of the third leaf in off of branches that were between 10 and 12” off the ground, and discovered that there was a significant difference in the stomatal density of the polluted plants compared to the control plant. In those of the polluted plant the average stomatal density calculated out to be around 105 per (mm2) and those of the non-polluted ranged to about 125 per (mm2) proving my hypothesis correct that CO2 do affect plants stomatal density (but more plant samples are required and controlled environments are needed to test the effects of each type molecule in the air to see what is truly causing the plants stomata to lower and to fully prove my hypothesis on whether CO2 is the main factor).
Many experiments and tests are needed to complete the validity of the hypothesis. For example several different factors are needed to expand a further understating on how pollution affects the plants. The testing of several different species of plant and testing in several different locations where plants could be subjected to different levels of air pollution are needed to fully understand how it affects plants as a whole and not how just one specific plant reacts to pollution. Some sources of error could include variations in type of air pollution such as diesel emissions, gas emissions, cigarette/cigar smoke (O3, SO2, NOx, H2S etc…), how healthy they plant is, how often its watered, elevation, the effects of insects and animals in the surrounding area causing damage to the leafs and the amount of sunlight the plant gets would all be factors.
These are some results of a similar experiment that Derek conducted where the air pollution was cigarette/cigar smoke instead of car emissions. The results of both these experiments further proves that the original hypothesis was correct because the data collected from the smoking section shows that the stomatal density of those plants took a serious loss in stomata. (P=.000000007)

We then compared our data together but we used two different methods of stomata collection I had used the method where I would search each leaf for the largest cluster of stomata. My partner Derek used the method where he would choose the exact same location on every leaf and collect the number of stomata.

In a study conducted by Acsess (Alliance of crop, soil, and Environmental Science Societies) L. H. Allen Jr. wrote “Gaseous pollutants (O3, SO2, NOx, H2S) affect plants adversely primarily by entry through the stomata. An example calculation showed that reduction in stomatal conductance by doubled CO2 could potentially reduce the effects of ambient O3 and SO2 by 15%. However, information on the interaction of CO2 and air pollutants is scanty. (Allen Jr.)”
https://dl.sciencesocieties.org/publications/jeq/abstracts/19/1/JEQ0190010015

So overall our research is showing us that there is a very clear cause and effect of car emission and cigarette smoke on plants but the underlying fact is that more research is needed to complete our final analysis to figure out the full on cause that air pollutants have on plants. There was one very interesting thing that we discovered while conducting our research. When we had applied the nail polish to Mahonia nervosa we found that the samples from the forest had turned brown in the locations where we had painted the nail polish on and the samples from the parking lot and smokers section remained unchanged. We do not know what had caused this but found it quite interesting and would hope to do more research to find the cause of this occurrence.

References:
JOSEP PEÑUELAS, ROSER MATAMALA; Changes in N and S Leaf Content, Stomatal Density and Specific Leaf Area of 14 Plant Species during the Last Three Centuries of CO2 Increase, Journal of Experimental Botany, Volume 41, Issue 9, 1 September 1990, Pages 1119–1124, https://doi.org/10.1093/jxb/41.9.1119

Allen, L. H. 1990. Plant Responses to Rising Carbon Dioxide and Potential Interactions with Air Pollutants. J. Environ. Qual. 19:15-34. doi:10.2134/jeq1990.00472425001900010002x

Franks, Peter J., and David J. Beerling. “Maximum Leaf Conductance Driven by CO2 Effects on Stomatal Size and Density over Geologic Time.” PNAS, National Academy of Sciences, 23 June 2009, www.pnas.org/content/106/25/10343.full.

Zeng, Eddy Y. “A New Page for Environmental Pollution.” Environmental Pollution, vol. 204, 2015, pp. 1984–1990., doi:10.1016/j.envpol.2015.06.003.

Sucharov, Lance, and C. A. Brebbia. Urban Transport IX: Urban Transport and the Environment in the 21st Century. WIT, 2003.

parking lot collection area

brown spots found on forest samples after nail polish was applied

parking lot samples

forest samples

Panorama of forest collection location

stomata view under (400x) magnification

The mysteries behind crown shyness

First off what is crown shyness? Crown shyness is an phenomenon in where the leaves and branches of one tree don’t touch those of other trees. This includes trees of the same species. According to the Forest Research Institute of Malaysia some of the possible reasons behind this include that for example, if one tree were to get sick with some sort of virus or an infestation of some type of insect or

animal, this type of phenomenon would become some sort of defense mechanism to prevent the spread or contracting of any of these harmful organisms. Another reason scientist speculate is that this phenomenon occurs is that the branches could harm themselves or one of its nearby trees. This could be caused by the branches blowing in the wind and hitting one anther or by one of the trees shading the other and stunting its growth. The final theory is that plants can feel when they are getting to close to one another, they do this by sight. In the book What a Plant Knows, Daniel Chamovitz discusses that plants can see certain types

of light such as bright and dark tones. So when the plant sees that its being shaded by a nearby tree, the plants halts their growing process the prevent them from out shading one another. Unfortunately none of these theory’s have been scientifically proven so their could be many other reasons why the plants would do this, but until then the mystery remains unsolved.

Chamovitz, Daniel. What a Plant Knows: a Field Guide to the Senses. Scientific American/Farrar, Straus and Giroux, 2017.

Cleaning the air with plants.

With the current state of the world today we know a lot of things about pollutants and how they are affecting our planet. But how many people know about the pollutants that are affecting us in our own homes. As you know humans consume oxygen and produce carbon dioxide in order to breath, but did you know that it would only take you 4 days to die from Co2 toxicity if you lived in a sealed 10ft x 15ft x8ft tall room (the average two person college dorm is

roughly 14ft x 15ft x 10ft tall). On top of that many people don’t know that they have other toxic chemicals floating around their homes, like trichloroethylene which evaporates into the air very quickly commonly used for dry cleaning and degreasing. Xylene and benzene both found in tobacco smoke, ammonia found in window cleaners and floor waxes, formaldehyde found in paper bags, wax papers, and napkins which are all commonly found in homes are extremely toxic. But with proper ventilation many of these toxins are prevented from accumulating to cause serious heath affects, but that doesn’t mean their still not there. So how do you get rid of them? Well one simple and easy solution would be plants. In a study formed by NASA made back in 1989 to figure out what plants would be best to take up in space shuttles to help produce oxygen and reduce toxin in the air of the shuttle; they discovered that not only do plants clean the air by use of photosynthesis (where the plant takes Co2 sunlight and water and creates sugar for energy while releasing O2 from the water) but plants also take in the harmful chemicals that we may be breathing in. The plant does this by absorbing the toxins through its pores or stoma then is transferred to the roots where a particular fungi in the soil attaches its self to the roots of the plants and absorbs the toxins. NASA then went to further research which plant would be most effective at cleaning the air. They chose plants that would flourish in reduced sunlight allowing them to photosynthesize well in house

hold light. They then took a list of plants and placed them in an air tight room to see the percentage of chemicals reduced in the room over a set period of time. In their final study they found that the English Ive was one of the most effective plants along with aloe vera, ficus and peace lilies. For their full study and analysis go here: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930073077.pdf

and a updated final analysis with pictures can be found here:  https://www.boredpanda.com/best-air-filtering-houseplants-nasa/

Soil Vs Hydroponics VS Aquaponics

The battle between what method is the best, and the short answer is… it depends. Before we dive in to which one is best, lets see what the differences are between the three. First we have soil which is an ideal combination for growing plants because it consists of sand silt and clay with some compost or fertilizer mixed in. Second we have hydroponics, which is a more modern style of farming widely popular for people living in city’s because of its compact and mess free set up. There are many different types of hydroponics, but a basic hydroponic is constructed by setting up a medium size tube where you connect a water pump, and drain system to a reservoir so that you have water consistently flowing through the tube. You then start by drilling holes in the top and drooping the roots of the plant in the opening then finishing off by adding liquid plant food and other essential nutrients.

Finally we have aquaponics which is very similar to hydroponics, but instead of using flowing water you grow your plant on top of a fish tank. Where the roots of the plants are submerged inside the fish tank and the fish provides all the nutrients the plant needs to survive.

Now that you have a basic understanding, which one is the best out of the three? Well in terms of best the hydroponics and aquaponics are certainly best in how much they grow, due to the plants ability to have water and nutrients at all times. The aquaponics method is best in terms of its cost effectiveness and the lack of time needed to take care of the plants, simply because all you need to do is feed the fish and top off the water every once in awhile and the rest takes care of its self. But in terms of quality the soil has both aquaponics and hydroponics beat. Over all any of these methods will work great for any type of growing

Rauscher, Frank. “Soil vs. Hydroponics: What Method Grows the Best Plants?” Maximum Yield – Your Modern Growing Resource, Maximum Yield Inc., 1 Aug. 2017, www.maximumyield.com/soil-vs-hydroponics-what-method-grows-the-best-plants/2/3428.

Patterson, Susan. “Which Soil Is Best for Plant Growth?” LoveToKnow, LoveToKnow Corp, garden.lovetoknow.com/wiki/Which_Soil_Is_Best_for_Plant_Growth.