Author(s): Zainab Qazalbash
Mentor(s): Dr. Changwoo Ahm, Ecology and Sustainability
AbstractWetlands are one of the most productive and biologically diverse habitats, serving several ecosystem services such as carbon sequestration, nutrient cycling, water quality improvement, flood protection, erosion control, and recreation. Wetland soil, which is also known as hydric soil, promotes biogeochemical processes that result in the accumulation of organic matter in the soil. Soil color can be an indicator of soil processes and can be an important tool in delineating wetlands, determining a soil’s ability to sequester carbon (via organic matter accumulation) and its redox potential. Mesocosms are excellent research tools that allow for the analysis of soil properties in created wetlands. Ahn Wetland Mesocosm Compound located at George Mason University contains 40 wetland mesocosms which can be used to study the effects of different variables such as plant diversity and fertilization on wetland soil. This study analyzed the effects of fertilization and plant diversity on the soil color of wetland mesocosms, and we predicted that the soil of planted and fertilized mesocosm will be darker in color due to higher organic matter. Our results could not prove a difference in soil lightness (i.e., L value) between unfertilized and fertilized or planted and unplanted wetland mesocosms, but this study has helped in further understanding of the use of the Nix Pro color sensor and its related applications in determining the state of soil color. Further studies are necessary to couple the results of the NIX pro color sensor and lab analysis of soil organic carbon (SOC) from the wetland soils.
Audio TranscriptHi everyone. My name is Zainab Qazalbash, and I am a senior Biology major. This semester my ecology and sustainability class has been conducting research with Dr. Ahn in his wetland mesocosm compound where we analyze soil color of the wetland mesocosms using NIX pro color sensor.
If you are wondering what a mesocosm is, it is a combination of two words, “meso” means medium and “cosm” means world. It is an outdoor experimental system that examines the natural environment under controlled conditions. The Ahn Wetland Mesocosm Compound (AWMC) is located at campus drive on Fairfax campus of George Mason University. It has 40 wetland mesocosms and it provides a means of conducting ecosystem-level experiments under controlled and repeatable conditions. It is designed to study the effects of different variables such as plant diversity and fertilization on wetland soil. The color of wetland soil, which is also known as hydric soil, can tell a lot about the soil’s organic matter. Usually, darker color indicates a higher level of soil organic matter.
Here are a few pictures of our wetland mesocosms. To study the effects of plant diversity on the soil in a wetland these mesocosms were planted with 0-4 species of plants and some of the mesocosms also received fertilizer treatment. Over the course of several years, unplanned mesocosms were occupied by invasive species such as cattail. As you can see here, on the right-hand side, this mesocosm was initially unplanted but now is dominated by cattail.
We have hypothesized that fertilized and planted mesocosms should display darker soil color due to the high content of organic matter. Fertilizer should aid the growth of plants which should add to the organic component of the soil in the wetland mesocosm. Plant diversity should also lead to darker soil color as a diverse vegetative community could enhance nutrient cycling, and increase productivity and carbon storage potential of the soil.
We analyzed the top two inches of the mesocosm soil in the replicates 5 through NIX Pro color sensor. Figure 5 is a picture of what NIX pro color sensor looks like. You place it directly on the sample and it sends you the color variables to your app and you can see several color variables such as L, A, B, X, Y, Z. For our study we used the L variable which means lightness, where the lower number represents the darker soil color.
This graph represents the comparison between the fertilized and unfertilized mesocosms L values. The fertilized mesocosms had lower L values and the unfertilized mesocosms had higher L values. As mentioned before, lower L values mean darker soil color so this study supports our hypothesis which suggested that fertilized mesocosms should have lighter soil color. However, when we performed a T-test we found that P-value was 0.2 so no significant difference was found between the soil color for fertilized versus unfertilized mesocosm soils.
This graph is representing the comparison between planted and unplanted mesocosms we see that the unplanted mesocosms had lower L value which means darker soil color and the planted mesocosms had higher earlier which means lighter soil color. This does not support our original hypothesis which stated that the unplanted mesocosms should have higher L value and less darkness in its soil. When we performed at Test our P-value was 0.9 so no significant difference between the soil color darkness was observed between planted and unplanted mesocosms
This study has helped understand the potential for use of NIX Pro color sensor in environmental monitoring and assessment. Additional studies are necessary to couple the results of NIX Pro color sensor and lab analysis of soil organic carbon from the wetland soils. It would also be interesting to see the color and carbon relationship between wetland soils under different variables such as fertilization and plant diversity for wetland soils. I would like to thank Dr. Changwoo Ahn for letting me do research in his wetland mesocosm compound and Dr. Stephanie Schmidt for her enormous support throughout my research. Thank you for listening and have a nice day.
If you are wondering what a mesocosm is, it is a combination of two words, “meso” means medium and “cosm” means world. It is an outdoor experimental system that examines the natural environment under controlled conditions. The Ahn Wetland Mesocosm Compound (AWMC) is located at campus drive on Fairfax campus of George Mason University. It has 40 wetland mesocosms and it provides a means of conducting ecosystem-level experiments under controlled and repeatable conditions. It is designed to study the effects of different variables such as plant diversity and fertilization on wetland soil. The color of wetland soil, which is also known as hydric soil, can tell a lot about the soil’s organic matter. Usually, darker color indicates a higher level of soil organic matter.
Here are a few pictures of our wetland mesocosms. To study the effects of plant diversity on the soil in a wetland these mesocosms were planted with 0-4 species of plants and some of the mesocosms also received fertilizer treatment. Over the course of several years, unplanned mesocosms were occupied by invasive species such as cattail. As you can see here, on the right-hand side, this mesocosm was initially unplanted but now is dominated by cattail.
We have hypothesized that fertilized and planted mesocosms should display darker soil color due to the high content of organic matter. Fertilizer should aid the growth of plants which should add to the organic component of the soil in the wetland mesocosm. Plant diversity should also lead to darker soil color as a diverse vegetative community could enhance nutrient cycling, and increase productivity and carbon storage potential of the soil.
We analyzed the top two inches of the mesocosm soil in the replicates 5 through NIX Pro color sensor. Figure 5 is a picture of what NIX pro color sensor looks like. You place it directly on the sample and it sends you the color variables to your app and you can see several color variables such as L, A, B, X, Y, Z. For our study we used the L variable which means lightness, where the lower number represents the darker soil color.
This graph represents the comparison between the fertilized and unfertilized mesocosms L values. The fertilized mesocosms had lower L values and the unfertilized mesocosms had higher L values. As mentioned before, lower L values mean darker soil color so this study supports our hypothesis which suggested that fertilized mesocosms should have lighter soil color. However, when we performed a T-test we found that P-value was 0.2 so no significant difference was found between the soil color for fertilized versus unfertilized mesocosm soils.
This graph is representing the comparison between planted and unplanted mesocosms we see that the unplanted mesocosms had lower L value which means darker soil color and the planted mesocosms had higher earlier which means lighter soil color. This does not support our original hypothesis which stated that the unplanted mesocosms should have higher L value and less darkness in its soil. When we performed at Test our P-value was 0.9 so no significant difference between the soil color darkness was observed between planted and unplanted mesocosms
This study has helped understand the potential for use of NIX Pro color sensor in environmental monitoring and assessment. Additional studies are necessary to couple the results of NIX Pro color sensor and lab analysis of soil organic carbon from the wetland soils. It would also be interesting to see the color and carbon relationship between wetland soils under different variables such as fertilization and plant diversity for wetland soils. I would like to thank Dr. Changwoo Ahn for letting me do research in his wetland mesocosm compound and Dr. Stephanie Schmidt for her enormous support throughout my research. Thank you for listening and have a nice day.