The Berry Fiends have been hard at work this entire semester on a discovery lab that attempts to determine more about one of the most invasive species in the Southern Ohio region, Lonicera maackii, better known as the Amur honeysuckle. Long before L. maackii began its overthrow of American plant species, Chinese gardeners used it in their gardens, and it intrigued visiting Europeans and inhabitants of the West because it was a novel and unique plant species (Luken and Thieret, 1996). Visitors from the West took the plant back overseas and introduced into the region of North America where it now grows prolifically. This hardy little plant was once considered a beautiful and fragrant addition to any home garden, until it began overtaking other important species, and growing wildly out of its intended boundaries. Fretting home horticulturists than began to worry that perhaps the honeysuckle would be far more difficult to extinguish than it was to institute. Several studies have been conducted to determine how much of the forest plant population has been overrun by honeysuckle, and one particular study conducted in the Oxford region by T. Hutchinson and J. Vankat, concluded that the plant spreads fastest in areas that are already densely populated by it. (1996). For all of the sweetness of its horn shaped flowers, the honeysuckle is a detriment to the surrounding plant populations. Its presence in an area undoubtedly means the end for indigenous plants that aren't as hearty or do not have the adaptations to beat the honeysuckle out for light and shade in the environment that they share.
Honeysuckle is quite abundant in all regions of the Miami woods area, and though decorated with fragrant white and yellow blossoms during the summer, as the winter deepens it begins the process of producing red berry type fruit for distribution of its seeds. It is approximately six feet in height, with dark green elliptical leaves. The berries remain on the shrub until January, unless birds eat them all before then. The seeds are ingested by the birds and dispersed in this manner. (Luken and Thieret, 1996) This lab focused on the berries due to the fact that they have been relatively unstudied by past botanists, and have not been studied in recent years by any first year NS students. The distribution of the honeysuckle plant through out the woods was the second part of the lab. The hypotheses that follow were formed through the collective brainstorming of the scientists involved in this study, as a means of defining what exactly leads to the honeysuckle being so resilient and able to exist anywhere. Obviously the honeysuckle's reproductive methods must be well sited to the climate and habitat of Oxford forests, so it was decided that an appropriate focus for the lab could involve the mechanism by which the plant reproduces.
The main problem being addressed in this experimental procedure for the first part of the lab is what effect differences in growing conditions have on honeysuckle berry production and ripeness. It is thought that the temperature and the location of the honeysuckle (either in direct sunlight or in shade) have significant effects on its productivity and rate of berry formation. It is also hypothesized that larger plants tend to produce more, and that plant size and abundance will be reflective of the environment in which it lives (be it sunny or shaded, crowded or sparse).
Our hypothesis for the second section of the lab relates to whether or not they the honeysuckle plants cluster together and were prolific in groups, or whether they were found more often by themselves growing heartily without competition from other plants. Our hypothesis was that there is a definite distribution pattern in which the plants are more often clumped together and singular plants don’t fare as well.
The lab proposes to accomplish the following things:
1. Collect honeysuckle berries and record data for berries size and quantity and then compare the data using statistics.
2. Through statistical correlation, determine which factors have most significant influence in the honeysuckle berries and which have little influence.
3. Become more proficient in field collection and sampling techniques.
4. Utilize STATVIEW and become more familiar with its workings.
5. Determine the factors that relate to fruit production (i.e. height and sunlight), and also affect the bigger picture of overall land distribution.
6. Determine the factors that relate to the growth distribution (i.e. clusters or by itself) and the characteristics (height, trunk circumference, and, height of first branch) in order to understand the way in which the honeysuckle grows.
This project is relevant to the larger issues of where and when it is appropriate to the measures against what J. Luken refers to as "biological pollution". The honeysuckle is in some ways an evolutionary marvel. Its leaves are out before other competing plants in the spring and loses its leaves latest in the fall, its berries are well designed for small animal consumption, it is amazingly resistant to cold, and it can grow well in shade and even better in sunlight. To get to the root of this issue, to really look into what can be done to allow cohabitation of the honeysuckle with the other surrounding plant species, it was necessary to complete research on the topic. This project speaks to that in a focused and organized way.
The first part of the lab consists of taking samples of honeysuckle trees in order to understand the differences in fruit production. On three different dates (9/24, 10/8, and 10/28) samples were taken from varying trees, one in the shade and one in the shade. The tree was then divided into sections. These sections include the top, middle, and bottom. In these sections one branch is chosen at random. This branch is then divided in half or equal sections. These sections are referred to as "interior" or "exterior" depending on the location of the berries. The berries closer to the middle of the tree were labeled interior and the ones on the outer part of the tree, exterior. As the berries are picked they are stored in plastic vies that are labeled according to their section. On all of the test dates the temperature was taken in order to relate the fruit production and ripeness to the temperature.
After each collection was taken, the test tubes containing the sections were divided according to the ripeness of the berries. There were five berry ripeness categories, which consisted of green unripe, small purple, large purple, small red, and large red or fully ripe. Division of the berries into these separate sections is a qualitative analysis that consists of observing the berries and then classifying them based on similar appearances. The green unripe berries are the tiniest ones, hard and completely or almost completely green. Small purple berries range in size from the size of a green berry to two or three times the size. Large purple berries are extremely full and appear dark purple, often times with purple stripes traversing them longitudinally. Small red berries have the characteristic fire-engine color of ripe honeysuckle berries, but are the same size or a bit larger than small purple. If the berry is really full and ripe, and much larger than its surrounding berries, it is classified as a large red. After dividing the berries, each one was weighed with an electronic gram scale. The weight of the berry in grams, and the section the berry is classified under (top-exterior, middle-interior, etc.) are recorded. This is done for all of the sections of the trees in both the sun and the shade. The information is then entered into STATVIEW. By entering the information, graphs and probability can be done. After figuring the statistics, it is possible to evaluate the results.
In order to understand the significance of this data six different test were done. These tests are as follows:
1. Comparing the amounts of berries produced for each plant for each day based on area of growth on plant.
In other words, a histogram and a chart of descriptive statistics (mean, median, standard deviation etc.) must be prepared for each tree that compares the amount of berries from each section (Top/ Interior, Top/Exterior, Middle/ Interior, Middle/Exterior, Bottom/ Interior, Bottom/Exterior). The group is trying to discover what patterns emerge in production based on where the berries are produced on the plant (the differences in sun, shade and temp will not be relevant).
2. Comparing the differences in overall number of berries produced per plant based on sun or shade.
The group will be expected to do a comparison of the amounts of berries produced in all of the shade plants vs. all of the sun plants. A histogram, an Anova (large scale P-value test) and descriptive stats will be created.
3. Differences in overall plant production based on temperature.
The plants will be compared from all three collections, grouped by sun or shade, to determine if there is an increase in berry production due to a decrease in temperatures over the six-week period. A histogram for each plant that shows amount of berries vs. temperature, an Anova test comparing all the plants in the sun and one comparing those in the shade and descriptive stats will be needed.
4. Comparing berry ripeness from section to section per plant.
This part will attempt to show trends in the ripeness of berries based on where they are located on the plant (same sections as above). Each plant will be analyzed individually, with a histogram and descriptive statistics for each of the six plants.
5. Comparing the ripeness based on sun/ shade differences.
For each day, the plants will be compared against each other to determine if patterns emerge concerning ripeness of berries, and the amount of ripeness of each berry. These comparisons can then be extended if necessary to encompass differences in all six plants. Anova tests can be done to compare all plants to one another to see if shade plants produce consistently fewer berries than sun plants.
6. Comparison of berry ripeness based on range in temperature. For these tests, all shade plants will be compared to one another, and all sun plants will be compared to one another, to see if ripening patterns occur as the temperature decreases. Histograms that compare ripeness level and amounts to temperature differences will be necessary, as will the Anova test and descriptive statistics.
All of these Statistical tests can be extended, but for simplification purposes, and to get data that can be easily correlated and compared, it would be best to focus only on the tests mentioned above. By taking the previous statistics and creating new statistics from a new berry collection the class can help determine the results. The class will better understand and be able to see the relation of berry growth to climactic influences.
We found that our sampling technique was very efficient and accurate. By contemplating the testing method several times, a method was produced. The first idea was to take random berries off different branches and different parts of the tree. This method was not accurate because it was very unlikely that it would actually be due to chance alone and that it would actually represent the different parts of the tree. By taking samples from every section of the tree, including interior or exterior, it would insure that we had berries from every part of the tree.
The idea to collect all the berries of the entire tree was considered but the task would have taken too long. It would be an overflow of information. The technique used, allowed us to have a method that was consistent. Each time someone would take samples it was guaranteed that the method would be the same. By taking the whole branch we were also able to get an accurate idea of the different sizes and ripeness variation throughout the tree. By taking samples every two weeks for six weeks, we experienced a notable change in temperature. This allowed for more accuracy in that the test was not just one time and there were several different trees to show how the honeysuckle tree differs in growth. The variety in testing and our testing techniques show that the sampling we took really represented the way honeysuckle actually grow. By looking at the temperature, the relationship to temperature and honeysuckle growth can be seen. The height can also be related to the growth of the tree. This allows us to consider different variables that effect the growth and that might have influence accuracy in our sampling.
The second part of the lab involved required the class to participate. We divided the class into three groups, each of which were defined a section of the forest to sample and map. The groups split up and with a member of the Berry Fiends to a pre-ordained honeysuckle testing sight. These sights were plotted at random by a member of this lab group in which a rectangle of three by five meters was marked of using the pink marking tape. These plots were chosen at random in a wooded area. Three plots were in the sun and three in the shade in order to see the relationship between the distribution and the condition.
After each group was assigned to a plot the group they were given a hand out that provide a map of the plot, conditions to look for, and questions about each plot. Within the rectangle, the experimenters were required to count every honeysuckle plant, and mark the number of plants found on their corresponding locations on the map. Every tree was measured, and the chart that was comprised of the height of each tree, the circumference of the base of the plant, and its relative location (i.e. singular or in a group).
Preliminary results from the attached data sheets and statistical calculations indicated a correlation between the variables that were expected. The honeysuckle plant in the sun produced far more berries than the shaded plant. It was possible to tell from observing the plant that the sunlight is large growth determinant. The leaves grew towards the light, and certain branches protruded in different directions straining to find the light. The top branches had the most berries in both plants, and on the shade plants the bottom branches had very little berries. The abundance of berries on the plant in the sun varied from section to section within the tree. The first tree was very thick with branches growing all around it. The top of this tree had the largest quantity of fully ripe berries. The middle sector had the most berries, but not as large a percentage of ripe ones as the top. The bottom of the sun plant did produce some fruit, but there were more berries in the exterior section than the interior.
The shade plant grew differently than the sun plant. The shade plant grew upward, searching for sun whereas the sun plant was more spherical. There were few branches on the bottom, and the branches started growing farther up. The tree had few berries especially lower down on the plant. The very bottom of the plant was almost berryless and the leaves appeared to be dying.
For the second collections the correlation between sun and more ripeness was found again. Also the second time, the berries were riper overall, with some of the largest berries being close to twice the size of the berries from the previous collection. Berry production was also found to have increased after the second sampling. The group thinks that this is most directly related to the gradual decrease in temperature experienced in the last two weeks. The second sample was similar to the first in that the berries tended to grow more abundantly in the sun, and at the top of the plant. This is demonstrated in the attached graphs.
In the third collection some interesting observations were made. The first and most important observation was the significant decrease in the number of berries. Also, the berries in this collection were riper overall. However, this does not mean that the weight increased. In fact, the third collection produced the smallest berries. This could be due the fact that over time plants loose their berries in preparation for the next year. Also, the extreme variation in temperature and amount of sunlight could have had a significant affect on when the plant looses these berries. Another very interesting observation was that the plant had almost twice as many berries growing in the shade as opposed to the sun.
After examining each individual collection, we can make overall conclusions about our lab findings. Even though we found out earlier that the third collection produced more berries in the shade, statistics show that there were almost twice as many berries found in the sun. In the beginning there was a significant difference in the weight of the berries based on their location in either the sun or the shade with the shade berries having a lower mean weight. However, the mean weights on the second collection were almost equal, and from there the berries in both the sun and the shade decreased in weight almost evenly. The second collection also produced almost twice as many berries as the first collection, and three times as many as the third. Berry location on the plant also had an effect on its size. In the sun, berries that were found in the top exterior of the plant tended to be the largest whereas the berries in the bottom interior were the smallest. Plants however, that were located solely in the shade had somewhat different characteristics. These plants produced their largest berries on the bottom exterior of the plant, with the smallest berries were still located in the bottom interior. We feel that the berries at the top exterior of the plant in the sun were larger because they received more sunlight, and the berries in the bottom interior were smaller because the lack thereof. As for the shade plants producing larger berries and the bottom exterior, we propose one solution. The plant receives nutrients from the soil, and instead of having to exert, and waste all the energy in producing berries at the top of the plant, instead it produces the berries at the first possible chance; the bottom. The reason the sun plant can produce large berries at the top is because it receives enough energy from the sun in order to do so, the plant in the shade however doesn’t receive any sunlight and therefore can’t do this.
The group also looked at p-values:
1. When the total mean weights were compared by date, the p values were all greater than .05. This shows that all three collections could have come from same population, and there was not significant increase in total mean weight. At every collection the total mean remained about .13 grams. (this does take into account the differences between sun and shade). When berry weights were graphed it was also shown that most of the berries fell between the weights of .07 and .15 grams.
2. When total mean weights were compared by sub-location on the plant, the comparisons which proved to be statistically significant (thereby the most likely to have come from different populations and to show a marked disparity between values) were top-interior vs. bottom-interior, top-exterior vs. middle-exterior, top-exterior vs. bottom-interior, (a result that was expected and proved our hypothesis that sun is the most important factor in berry ripening) top-exterior vs. bottom-exterior, middle-interior vs. bottom-interior, and middle-exterior vs. bottom-interior.
Comparisons for the second part of the lab turned out as expected as far as p-values. There was definitely a difference between the mean height of the first branch in sun plants vs. shade plants. A p-value of .0258 proved that there was a significant difference between mean heights in the shade vs. mean heights in the sun.
The group would however like to point out the error involved in our lab. First of all human error is a key factor in any scientific experiment. Human error could have occurred in a number of different places in this lab. The number of berries could have been miscounted, we could have forgotten to hit tare on the scale when measuring the berries, we could have had miscalculations, and we could have misinterpreted the data and graphs. Also temperature could have had a strong affect on our findings. In the last few weeks, Oxford Ohio saw a series of days with record-breaking temperatures uncommon to this time of year. This could have caused the honeysuckle plant to behave in strange ways thus skewing our data. Also, there were times in which our berries were stored in a draw for a day or two. This short period of time could have caused the berries to dry out, or even get smashed in the drawer.
As a group, we decided to display our results through line graphs, tables, and histograms. The graphs provide a quick reference and simple analysis of the data where the tables provide statistical calculations, and values for written interpretation. The major graphs that we decided to use are the ones we felt best represented and described what we were trying to discover. It should be noted however that we considered and analyzed each and every graph.
The Contributions of Fellow Class Members:
a. The Decomposition of Birch Leaves in Different Environments-In this experiment, this group gathered 50 leaves to test the ratio of leaves fallen per day. The group also gathered 25 leaves in three different stages. The stages were not very clear in the lab reports. This group is testing the hypothesis of whether or not the degree of decay affected the weight of the leaf.
b. Types of Sediment Distribution in Pfeffer Park Stream- This group's procedure is to come up with 3-5 environments and to take 5 samples form each environment. The group is measuring the weight, size, volume of water, velocity, and depth. They are taking a cross-section of the stream as well.
c. Effects of Acid Rain on Tombstones- This group is comparing the two graveyards in Oxford, Oh and the weather conditions in each one. They are using the method of compass orientation to measure the position of the graveyard determined by the wind location (N, S, E, W), They are using a Deterioration scale to measure the decay from the different eras. The pH's history is being taken to determine the effectiveness of acid rain from the 19th century to now. The group will also be meeting with other Oxford cemetery staffs in order to discuss depths of the engravings comparing older engravings to newer ones.
d. Effects of Acid in Limestone- This group's main equation is HCl and H20. They will be testing both calcite and limestone in order to have more beneficial results. The group is taking 40 total acid samples and 125 calcite samples. The group is going to monitor the acid and the interaction with rock. Group members observed that limestone, being a base would have to be neutralized over time.
e. Water Striders "Oh Jesus Bugs"- This group collected 20 spiders and observed them. Some of the bugs were found to have white stomachs, which is significant to the lab. Each specimen was also weighed and measured.
Discussion and Conclusions:
Now that the Berry Fiends have reached the end of the semester, there are many results for varying parts of this lab for which conclusions must be drawn. The first, main issue that must be addressed is how our results prove or disprove our hypotheses. When the lab originally began, the main hypothesis we focused on involved which external factors had the greatest effect on production and ripeness of honeysuckle berries. The Berry Fiends hypothesized that the plants which received large amounts of sun would produce more berries and that the berries would ripen faster. The fiends also hypothesized that as the winter closed in, there would be a significant increase of the ripening of the berries to prepare for the reproductive season. The results were completely tabulated, plants were compared based on their locations, and berry ripeness and abundances were compared based on sublocations. This allowed for a greater ability to correlate the data and make an analysis.
The first, main conclusion that we can draw from this lab is that sunlight is a significant factor in the production and ripening of honeysuckle berries. When the weights of berries were compared from sublocation to sublocation, there was an astounding difference in mean weight between berries located in the top-exterior and sunnier portions of the bush as compared to berries growing in the bottom-interior and therefore shadiest portion of the bush. As was also shown in results, plants located in the sun produced twice as many berries as plants located in the shade. All in all, sun was deemed the most influential factor in the growth and reproduction of honeysuckle berries and plants.
From these results, we can raise a couple of questions. First, why is the sun such an important factor in berry production? Next, how do honeysuckle plants that receive much less sun still survive as well as they do? The first question has a pretty simple answer. Light is a critical part of the photosynthesis process, and without it plants could not produce the food that they need to grow and propagate. It only serves to reason then that plant that receives more sunlight would be the most successful.
The second question, however, bodes some thinking. Honeysuckle, being an invasive species makes use of all of its available resources to grow and survive. Though the shaded honeysuckle does not receive enough light to grow as tall and wide as those in the sun, it still receives water, air, and nutrients from the soil that allow it to complete its life processes even in densely shaded portions of the forest. There is still some sunlight in these areas, and the honeysuckle has become extremely efficient in using the light made available to it. This allows it to grow in areas where other plant species might not survive re-enforcing its invasiveness.
The next issue of this lab that needs investigation is whether or not decreasing temperatures effect the ripening and production of the berries. It was thought by the lab group, that as winter drew near and the outside air drew cooler, the berries would accelerate in their ripening. This was, without a doubt, found to be the case.
The berries did complete their ripening process as the fall months waned. By mid-November, though no more collections were taken at that time, it was observed that no more unripe berries existed anywhere. All berries were full and ripe. Because honeysuckle berries, as we’ve learned through our research (J. Luken 1996 p 18-24), rely on being ingested and then redistributed by forest creatures it serves to reason that the berries would be fully ripe before the majority of the forest creatures went into hibernation or migrated south for the winter. The rich, red color that signifies the berry’s ripeness most likely serves as an indicator to the forest species that the berries are ready for consumption. In this way, the berries ensure that they will be ingested and passed through the digestive tract of the animal and deposited in another location. This allows for the honeysuckle species to distribute themselves over a large area of the forest, also leading to their invasiveness.
Though we at first concerned ourselves only with differences in ripeness and production of berries due to temperature and amounts of sunlight, eventually, we began to wonder how sunlight truly effected the overall plant growth and the amount of plants found in a certain area. After completing the second part of our lab and analyzing our new data, plants were found to be more densely packed in areas of sunlight. From this, we concluded that each plant sprouted additional trunks because of the large amount of sunlight they received. These plants were also taller, fuller, and more prolific than the sparse clumps of short plants found in the shaded areas. This coincides with research done by J. Luken and L. Kuddes in which they concluded that:
“Research on trees suggests that conditions of full sun include greater degrees of branching, greater horizontal expansion, and thus a multi-layered leaf display; shaded conditions induce greater vertical growth, less branching, and thus induced leaf position of a mono-layer in the forest understory”
It is possible that other factors played a role in why certain areas of plants were so densely populated with tall, healthy honeysuckles such as soil nutrient content, water availability, and lack of competing species. These aspects would all be suitable for further consideration in future labs.
The article “Landscape Structure and Spread of the Exotic Shrub Lonicera Maackii in the Southwestern Ohio Forest,” by T. Hitchinson and J. Vankat, found that honeysuckles tend to grow in dense clumps as opposed to sparse individual plants. However, in the forest behind Boyd Hall, lots of small isolated patches of honeysuckle were found, leading to the conclusion that perhaps the honeysuckle grows anywhere its seeds are distributed.
Perhaps the reason that Hitchinson and Vankat found that honeysuckles are most likely to grow in large, dense groups is that when the berries fall to the ground surrounding an existing plant, they most likely take root and grow in the same area as the mother plant. This leads to the tendency for honeysuckles to grow in clumps because, quite simply, they grow anywhere that their berries fall. Honeysuckles are not finicky in their growing habits and were found both in large masses as well as small, separate patches. This is one of the keys to their invasiveness!
Of course, in the true spirit of interdisciplinary science, it is necessary to determine where our work coincides and contrasts with the work of others. There has been a significant amount of research on the various growing patterns of honeysuckle, but as far as we know, we are the first to study the production and ripening patterns of honeysuckle berries. Although our project was perhaps not as extensive as those performed by J. Luken, L. Kuddes, J. Vankat, K. Woods, and others. It is clear that our research speaks to an interesting question that has never been fully explored. Much fretting and worry about the invasiveness of honeysuckle has occurred in the labs of horticulturists in our area and across the world. Perhaps by beginning this lab and synthesizing the data, another student in a later year will be encouraged to continue the hunt for knowledge about new ways to contain the honeysuckle or arrest its development.
Indeed, even the triumphant Berry Fiends will leave this project with some questions unanswered. For instance, what kind of chemicals would be needed to kill the honeysuckle without harming surrounding plant species? Also, which forest creatures are the most responsible for distributing the honeysuckels? What is the actual range of honeysuckle? In what countries does it not grow and why? How will it be possible in the future to prevent honeysuckle from invading these countries? Is there any place that the honeysuckle would not be suited f
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