bio presentation

Coast Live Oaks and English Ivy

Our research is on the relationship between two species in Arroyo Seco: coast live oaks-a native tree specie, and english ivy-an introduced specie that was introduced to the United States in the 1800s. We hypothesized the ivy have a exploitation relationship with the coast live oaks from the observation of the two species where the ivy benefits and the oaks is harmed. Our reasoning for our hypothesis is that ivy plant is bad for the coast live oaks because of the competition for the sunlight. Since ivy is known for its ability to climb to the top, and in order to acquire sunlight, and not able to support itself, the ivy has to climb on the coast live Oaks. Without climbing, it becomes impossible for the ivy to survive as it would require the light of the sun to help in the process of the photosynthesis. Consequently, the coast live oaks has to compete with the Ivy to obtain for the sunlight. We will first take a look at the ecological research of our two species.

        The scientific name of the Native Live Oak is Quercus agrifolia, which means field-leaved oak. The oak is also commonly known as California live oak and coast live oak. According to Natureserve ranking system the Quercus agrifolia is at a G5. This rating shows the Native live oak is common, abundant and secure in its status. The native live oak thrives in environments near the coast of California, usually within 60 miles of the Pacific Ocean. The oak prefers well-drained soil, mild winter conditions and can withstand the hot, rainless summers. According to (Gale, 1998) the oak is intolerant to shade and requires sunlight. The native live oak is considered to be one of the most important habitats for birds, small mammals, and other species. Along with other small animals the scrub jay and California ground squirrel rely on the acorns for food. Feral pigs and pocket gophers indicated by (McIntire, 1990) eat the roots from the oak as the main food in their diet. The Cooper’s hawk uses the tree as a home. The one species that completely relies on the native live oak is the California oak moth caterpillar (Phryganidia californica.) The caterpillar eats the fallen leaves off the trees, their only source of food. The caterpillars also fertilize the oak offering benefits for both the oak and caterpillar. The growth of the native live oak is four to eight feet tall. The oak has a strong root system with roots growing deep into the ground and also growing horizontal as well. This complex root system allows for the oak to absorb moisture during periods of drought. The leaves vary in size permitting the outer leaves to protect the smaller ones. The smaller leaves are able to produce photosynthesis more efficiently. Most of the acorns produced are dropped in the Fall, however ( Goulden, 1996) offers the native live oak holds most of its seeds (acorns) longer than other California oaks, some remain until Spring.  One of the most important adaptations to the native live oak is its ability to survive fire. The oaks thick bark keeps the inside safe, allowing the oak to withstand the fire. Even in extreme fire conditions where a tree is burned down the complex root system below the soil is safe supporting the production of new sprouts.

        Our group decided to study the non-native species which is known as Ivy, which is Commonly known as English ivy but scientifically identified as Hedera Helix. English ivy plant the Hedera Helix is a ground cover plant that spread horizontally and reaches to a height of about eight inches. The plant is also climbing plants and they can climb with a certain tree to a height of about fifty inches in which they add weight to the trees, making them more vulnerable to storm. These plants bear flowers that are greenish which are always evergreen and so they are foliage plants (Palmer, 2002).  The ivy plant usually do well in soils that are not neither fertile nor infertile or in other word, they do well in moderate soil. Sunny conditions also favors its growth meaning where these plants grow sun should be throughout but the soils must be moist and can’t do well in calcium areas (Headley, 1990). Deciduous forests and coastal climates are the original habitats for this English ivy (Palmer, 2002). Ivy plants are climbing trees and spread its branches and twigs thus affecting some plants since will prevent sun from reaching the ground and also prevents water vapor from the ground to penetrate and so photosynthesis of other plants that may grow along these plants will not take place effectively. This vine should be grown in well-drained soils and under shade and under tree plants that forms canopies. Some trees for example elms, oaks and other tree species are affected by this English ivy since its leaves produce a very dangerous pathogen that have side effect on those plants (Boersma, 2006). The English ivy plant Hedera helix was first introduced in 1727 in Europe, western Asia and countries that were colonized by European in northern Africa (Osborne, 1984) .It then spread to United States due to increase in demand in its market as a valuable plant for ground covering. This evergreen vine is widespread in western Washington.

        After doing some researches on the both plants, we discovered that the two species indeed have a exploitation relationship where the ivy benefits and the coast live oaks is harmed as we hypothesized. But why the oaks are harmed is different from our hypothesis of competition and sunlight. The ivy benefits by being able to grow high up in the tree to obtain sunlight. According to the American Ivy Society, the ivy growth doesn’t deny the tree sunlight needed for healthy growth. However, ivy growth will provide other invasive species like insects and rodents as home to grow, which can lead to infestations and damage to the coast live oaks. Furthermore, the Ivy can steal nutrients and water from trees it wraps around, and can accelerate tree rot by holding moisture close to the tree trunk. The ivy can also make the oaks more vulnerable to storm by adding weight to the oaks. In addition, the ivy produce a pathogen that weakens and kills the oaks. Hence, Ivy growth is not only non-beneficial but harmful for the Coast Live Oaks.

        Lastly, our group think that the Ivy should be removed from the coast live oaks because of it’s potential danger. Although the coast live oaks is in a secured and safe status, the coast live oaks with ivy can be in a dangerous spot with a natural disaster such as storm and tornado. Other than that, the present of ivys can be a threat to many plant species due to its nature to oushadow the other species and prevent them from making food from photosynthesis. However, it is hard to remove the Ivy completely due to English ivy is an aggressive invader and it can grow easily. Nonetheless, removal of ivy from live oak trunks is possible, but it only takes time.

       

References

Palmer C. (2002). English Ivy. Wheaton, IL: Tyndale House.

Hedera helix (English ivy). (n.d.).

Boersma, P. D., Reichard, S. H., & N., V. B. (2006). Invasive species in the Pacific Northwest. Seattle, WA: University of Washington Press.

Osborne, L. S., Chase, A. R., & Henley, R. W. (1984). English Ivy. Apopka, FL: University of Florida, IFAS, Agricultural Research Center-Apopka.

UC Berkeley (2002, December 9). Fact Sheet: Sudden Oak Death. Retrieved February 1, 2016 from,http://nature.berkeley.edu/garbelotto/english/factsheet.php

Wilken, D and Burgher, J (2000, September 18). Coast Live Oak. Retrieved February 1, 2016 from,http://plants.usda.gov/plantguide/pdf/cs_quag.pdf (Links to an external site.)