Science Buddies: "Ask an Expert"

im a sophomore in high school and i was just wondering if anyone had any ideas to help or to advise me what i should do for my experiment.
I will build 10 rectangular wooden boxes (9”x12” and 5 inches tall) that will hold 4 different kinds of extremely hardy and drought resistant plants that have been determined by my mentor to be able to survive the temperatures of a roof. Four were chosen and they are as follows, Self Heal – Prunella vulgaris, Beach Strawberry – Fragaria chiloesis, Sea Pink – Armeria maritime ssp. californica, and Stonecrop – Sedum spathulifolium. These plants act as a “roof” on the box. Additionally, I will also build a box with composition shingle on top, which is found on many houses today, and an empty box with no roofing on it or soil on top, both of which will act as part of my control group. (A diagram of what the boxes will be composed of and look like is attached to the proposal.) These plants are very readily available at almost any nursery or garden store and are relatively cheap to purchase. Fragaria chiloensis is an evergreen flowering plant, Prunella vulgaris is an alternative medicinal plant, Sedum spathulifolium is a succulent, and Armeria maritime ssp. californica is a rockery plant that is often found on coastlines. Out of the 8 boxes with plants in them, four will have 1 type of plant species per box and the other four will have a combination of the plants. For comparison, I will be using plants a, b, c, and d. In the eight out of ten boxes that have plants in them, I will have one box with plant a, another with plant b, plant c in another, and finally plant d in another. Then I would have plants A, B, & C, A, B &D, B, C & D, and D, A & C in the remaining 4 boxes.
The boxes will promote plant growth but prevent the plants from growing into the roof which will consist of an impermeable layer of plastic, stopping the plants from growing into the roof, and rocks and soil to help drainage and prevent root rot. Similar boxes have been used by Heather Farms nursery staff in local community projects.
I will place each of these boxes on top of my roof in an area that will receive both shade and direct sun throughout the day. I will also drill a small hole in each box in order to take the temperatures of the inside of each box with a probe thermometer, and after the temperature is taken I will put a dowel inside of the box in order to stop loss of heat, which would destroy the integrity of the experiment. Additional recordings will include the ambient air temperature, the surface temperature of the boxes, and the temperature of the roof. I will then compare the data collected between each box as well as to the air temperature of each of the control boxes and present a chart with the findings. I will take the temperatures once at 7 am, 4 pm, and 7 pm every day for two months. And I am planning to start the experiment during the months of October and November. Each day, I will water the plants in order to help the plants grow, and I will water them at the end of every day after I have taken the 7 PM temperature reading, and I will give each plant 12 oz of water and will use MiracleGro® fertilizer mixed with the water once weekly.

and the box i will build will be build like this

plant
soil
rocks
layer of plastic (as the impermeable layer)
layer of wood
then air space (to take the temperature in)
then the bottom of the box

any suggestions?
thanks

Hi there,

It sounds as if you have your experiment fairly well planned out. I do have some questions, though.

What are you trying to measure? Is your question "Which plant makes the best roof material?" If that's your question, what determines the "best" material? Are you looking for temperature stability inside the box, or ability of the plant to withstand the conditions on your roof?

I'm also not sure I understand your reason for combining plants in some of the boxes. I think you might be better off doing replicates (multiple boxes with the same plant), to make sure that you don't lose results due to one particular plant dying. Can you explain why you wanted to combine the plants?

Also, what kinds of suggestions were you looking for? Did you want us to comment on your experimental design, or suggest other variables to measure?

Please post with more information, and I'll try to help you!

Heather

thanks for those suggestions. i am planning to measure the temperature between the two layers of wood as i described in the previous post. the box will be like as though there is actually a box inside the other box. but the plants that i will put up in boxes on my roof will be drought resistent, and strong enough to last up there and im trying to compare them to each other to see which plant is the "best" at cooling or warming the inside of the box/"house."

well the reason for making combinations is becaues when i did research on places that have green roofs, one was the california academy of sciences and they used 9 types of plants on their roof and i wanted to see whether it was a good or bad idea to use a variety of plants.

tahnks for your help

Based on your description, I really do think you should do multiple replicates for each plant (at least 3 each - 12 boxes total). It will be very difficult to interpret your data for the mixed-plant treatments. Having single plants per box, and multiple boxes per plant, will allow you to easily interpret your data and even do statistics.

Keep us posted as your project progresses!

Heather