Elephant Ears Essay

Testing the Growth Rate of Elephant Ears (Colocasia esculenta) and Irises (Iris versicolor)

INTRODUCTION

Global change is taking place every day; therefore, it is important to understand how human activities and behavior alters the biodiversity and functions of ecosystems. Alien species is a stimulator of major changes in ecosystems (Vila et al. 2011). An invasive species, is a non-native plant, animal, or fungus that moves to a new ecosystem in a foreign environment. Invasive ecology explores how the invasive species affect the economic, environmental, and human health on the new environment. For example, invasive ecology studies how an invasive species tends to crowd out and sometimes replace a native species (Richardson and Pysek 2008).

Community ecology studies the interactions between coexisting populations (add citation). Since it can be difficult for scientist to initially determine if a species invasive or non-invasive, they need to intensely study the species.
Colocasia esculenta, wild taro or elephant ear, is an invasive plant because it is known to disrupt native plant communities and then displace the native plant species (Figure 1). It is a fast growing plant with a tendency to spread if the conditions are favorable. They grow best in areas with high rainfall and warm temperatures in freshwater wetlands and sometimes in dry lowland environments. Taro has been founded naturalized in the Galapagos Islands, in different parts of Africa, and in the Canary Islands. Since Taro is considered the fifth most consumed vegetable worldwide, it has been transported around the world; thus, favoring the plants dispersal outside cultivable or gardened areas. The movement of the vegetative fragments is one of the primary ways elephant ears spread. Elephant ears have become invasive to many southern states including, Louisiana, Texas, Florida, Georgia, Mississippi, and Hawaii (Garcia-De-Lomas 2012; BREC Bluebonnet Swamp Nature Center, personal communication: Kikuta et al. 1938).
In Louisiana elephant ears are beginning to feed into the process of waterways disappearing. Not only do the elephant ears out-compete many native species, they also are beginning to modify the habitats. The elephant ears provide no food for the bayou inhabitants, meaning they are continuing to grow down the stream with no natural process of removal. Since there is nothing eating the elephant ears, they begin to narrow the stream, which results in a modified habitat (Tuhus 2009). Many techniques such as pulling the plants or cutting the plants out, freezing the plants, finding a native plant to crowd them out, and herbicide have been used to try to wipe elephant ears out; however, none of these have been proven effective since the elephant ears are continuing to grow (BREC Bluebonnet Swamp Nature Center, personal communication: Kikuta et al. 1938).
Iris versicolor, plant native to Louisiana, is normally used as a beautiful display; however, the root masses of the iris provide good shoreline protection (Figure 2). Normally, they are found in marshes, swamps, along shorelines, and in forested wetlands and are native to Canada, the lower forty-right states, and St. Pierre and Miquelon, France. When living in an environment full of moisture and good soil organic levels, the plant thrives without any commercial fertilizer. As of now, there is nothing that has a negative impact on the species. (USDA 2016).
The purpose of our project in the class is to compare invasive species to a native species.

Since elephant ears are extremely invasive in freshwater wetlands including in Louisiana, the overall question of our experiment is to see how we can manage elephant ear and what native species can resist them. The answer our class specially is looking for is if irises resist elephant ears. Overall, we hope to gain knowledge on how to control elephant ears. The experiment was set up to address the purpose by pairing up the species in 3 different combinations, EE EI and II, in three replicates to see their interactions with each other. Each group has a single barrier type, which would be one of the following: no barrier, root separate barrier or foliage separate barrier. The purpose of the barriers is an experimental control to observe if it makes a difference on the growth of the plants and the purpose of the root weights and stem weights are for finding the growth rate of each plant. The alternative hypothesis is that elephant ears will have an effect on the growth rate of the Iris and the null hypothesis is elephant ears will not have an effect on the growth rate of the iris. Through all the information taught this semester, the EI treatment, Iris grown with the elephant ears, will have a smaller growth rate than II treatment, the iris that are growing

together.

MATERIALS AND METHODS
The two plants in the experiment are the invasive elephant ears and the native irises. The materials needed were elephant ears, irises, soil, fertilizer, spoon, measuring tape, pen, popsicle sticks, pots, water, and barriers. Each group was given a single barrier type, which was either no barrier, above barrier, or below barrier. Depending on your specific barrier, there was a chance of more materials needed. The extra materials needed for the above ground barrier were cardboard and hardware cloth strips; the extra materials needed for the below ground barrier were bamboo stakes and chicken wire strips.
On February 2, 2016, each group began setting up their experiment by pairing up the species. The three pairings were: elephant ear with elephant ear, EE; iris with iris, II; or elephant ear with iris, EI. First, the elephant ears and the irises were washed off and then trimmed where the stems would be same height. Next, initial measurements were taken of the stem length and the total weight. Then, the plant pairs were planted in pots that were filled with soil a little over half way. Each plant in each pot was labeled using a popsicle stick. The way they were labeled was with the section number, group ID, treatment, and plot number on the stick. After the plants were labeled, fertilizer was sprinkled over the soil. Depending on the barrier type there could be one more step before going into the green house. Once in the green house, the plants were placed into a trays and then the trays were filled with 6 centimeter of water. The process of watering the plants, which was filling the tray with 6 centimeters of water was completed every Monday, Wednesday, and Friday.
On March 1, 2016, the second collection of data was recorded and then about a month later on April 12, 2016, the final measurements were taken. These final measurements included stem length in pot, stem length from korm, korm weight, stem weight with no leaves, and stem weight with leaves. The growth in each treatment was found by dividing the final data collection by the initial data collection. These measurements were then inserted into excel and an ANOVA test was run to analyze the results of the data collected.