Survey of Tree Variation and Type in Maritime Forests. Amy Dobson. Andrea King. Dr. Melear. Science Ed 506

Transcription

1 Survey of Variation and Type in Maritime Forests Amy Dobson Andrea King Dr. Melear Science Ed 506 Mini-term 2006

2 Abstract Significant interest in the variation and type of tree species in maritime forests was the impetus for the study. The study focused on the species of tree and the overall health of the tree species in transects along the coast of Ossabaw Island, Georgia. Researchers hypothesized that most prevalent and healthy tree species would be pine. Data was collected by organizing the start and end point into transects. After walking for ten minutes researchers would determine the data point and record the variation, type, and health of the tree species present in an approximate 100 yard line from the shore. Palm trees had the highest average health rating at 3.7, followed by the pines at 3.3, and finally the oak trees at 2.7. Palm trees were also the most prevalent species of tree. Future research could help discover the reasons for the prevalence and health of species observed.

3 Introduction The purpose of this study was to survey the type, variation, and health of trees in a maritime forest. The study was conducted on Ossabaw Island, Georgia. Researchers were interested in completing a survey of the tree type, variation, and health because of prior observations during walks on the island. Some tree types appeared to be more prevalent on different parts of the island. Also, when walking toward the south end of the island more dead trees were found. The goal was to discover what types of trees grew in what types of environments on the island. Researchers hypothesized that the most prevalent and healthy species of tree would be pine. Previous research on tree type, variation, and health in a coastal environment is scarce. Information and research on maritime forests is also very limited. However, research on various topics involving maritime forests has been written. First, let us define a maritime forest. A maritime forest is a forest dominated by pine and located on the mainland side of a barrier beach or island. These forests are located in or around the range of salt spray. These forests experience a large amount of change in a small amount of time. Conner et al (2005) describe the effects of natural disasters on maritime forests located in South Carolina. Bulls Island is a barrier island in South Carolina which was affected by hurricane Hugo in Researchers examined number for pine, palm, and oak trees in 1991 and used data from before the hurricane. The main tree species experienced change in different ways. Pine trees were almost wiped out by the hurricane, oak trees experienced a one third decline, and palms nearly doubled their numbers. Some factors that may have contributed to selective tree type are discussed. species on Bulls Island were the same found on Ossabaw Island and indicated the resilience of maritime forests.

4 More proof of the resilience of maritime forests is found in Rego et al (1991) s research concerning succession. The under story of the maritime forest was the focus of this study and researchers determined major species cover and frequency. Fires are integral to conifer development, but may harm other maritime forest species. In this study researchers found that the forest rapidly recovers from fires. Another finding was that diversity was almost unaffected. This explains why areas of the island may appear to have burned recently but species that live beneath recover quickly. One area of the island was a clearing that appeared to have recently burned. Underneath the dead trees the ground cover did not appear to be damaged by fire. This is another example of how the environment of a maritime forest can change quickly and the resilience of the forest. The maritime forest is composed of three main species of tree; the palm, pine, and oak. These forests are located in areas that are constantly changing, but the forests are adept at changing and surviving. In this study a survey of the main species and their health was the central focus.

5 Materials and Methods The materials used in this study were pen, pencil, and paper. These instruments were used to gather raw data including tree species and health. A digital camera was also used to visually capture the ten data points. The raw data was then transformed to an Excel file which was then analyzed using the ANOVA test. Researchers began at a prescribed point (an instructor s tent). Then researchers walked south for ten minutes. At each ten minute increment the type and health of the trees observed in approximately a 100 yard area were recorded. At each data point pictures of the area were taken. After ten data points were recorded the data was complete.

6 Results The tree health that was recorded as VH (very healthy), MH (medium health), PH (poor health), and dead were translated into a numerical value one through four with four being very healthy and one indicating a dead tree. The average health of each tree type was determined for each interval (1-10) and is illustrated in Graph 1. [For a break-down of individual data at each interval see the appendix]. Graph 1: health by type and interval number. Health by Interval Health Oak Palm Pine Interval Next the average health of each tree type was determined using all of the interval data. The oak trees had an average health value of 2.7, the palm trees were 3.7, and the pine were calculated at 3.3. The ANOVA test was used to determine if the difference in these averages was of any statistical significance. It was found to be significant with a p-value of Graph 2 represents the differences in average overall health by tree type.

7 Graph 2: Overall Average Health by Type Average Health by Type Average Health Avg. Health 0 Oak Palm Pine Type Next, the number of trees at each interval was examined and compared with the average tree health (not divided by type). Chart 1 and Graph 3 depict the respective number of trees and the average overall tree health at each interval. Chart 1: Average Health at Each Interval Interval of s Average Health Average

8 Graph 3: Average Health at Each Interval of s and Average Health at Each Interval 16 Average Health Rating and of s of s Health Interval

9 Discussion/Conclusions The success of any organism depends upon how well the organism is adapted to the environment in which it is located. The three tree types in this observational study were in the same environment (albeit slightly different at each of the 10 intervals). However, oaks, palms, and pines are different in some very fundamental ways. For example, root size and complexity, leaf structure, and bark structure to name a few. It is not surprising to find that, given such differences among the species, there would be a significant survival differential. The palm trees were found to have the highest average health rating at 3.7, followed by the pines at 3.3, and finally the oak trees at 2.7. Unfortunately, it was beyond the scope of this experiment to determine what caused the difference. Was it a difference in ability to withstand salinity? Could the palm trees fare better because of a shallower root system? Do the oak trees die off more frequently because there are more leaves to sustain? The intervals with more trees demonstrated a corresponding increase in overall tree health. This trend may provide cues as to which intervals were home to the more favorable conditions. As we walked from the campsite to the south beach the conditions varied. At the starting point (Helen s tent) there was a considerable grassy marsh that was between the ocean and the embankment. Counting always began at the embankment or first dry sand. Traveling further down toward the slough there were some areas where the sand dunes were quite high and others where there was not much evidence of a dune at all. It would be interesting to determine if a significant difference in salinity was present between the starting point and the last interval.

10 Bibliography Conner, W. H., Mixon, II, W. D., & Wood, G. W. (2005). Maritime forest habitat dynamics on Bulls Island, Cape Romain National Wildlife Refuge, SC, following Hurricane Hugo. Forest Ecology and Management. 215, Rego, F. C., Bunting, S. C., & da Silva, J. M. (1991). Changes in understory vegetation following prescribed fire in maritime pine forests. Forest Ecology and Management. 41,

11 Appendix Raw Data Start (Point 1): Sand dune then slough then land (Helen's tent) 1 Palm 4 2 Palm 4 3 Oak 4 4 Oak 4 5 Palm 4 Baby 6 Palm 4 Baby 7 Palm 4 8 Palm 4 9 Palm 4 10 Palm 4 11 Pine 4 12 Pine 4 13 Oak 4 14 Oak 4 Avg. 4 Point 2: Water in slough then sand dune then trees (Bone Yard) 1 Oak 3 2 Pine 3 3 Oak 3 4 Pine 2 5 Pine 2 6 Oak 1 7 Palm 1 8 Palm 1 Avg. 2 Point 3: Water in slough then sand dune then trees 1 Palm 4 Baby 2 Oak 4 3 Oak 4 4 Palm 4 5 Palm 4 6 Palm 4 Avg. 4

12 Point 4: Slough water then sand bar with pools of water left from high tide more sand and then trees 1 Oak 1 2 Palm 4 3 Palm 4 4 Pine 4 5 Palm 4 6 Pine 4 Avg. 3.5 Point 5: Slough then flat sand with first dead oak 1 Oak 1 2 Palm 4 3 Oak 3 4 Oak 4 5 Palm 4 Avg. 3.2 Point 6: Water with sand dune then trees 1 Oak 1 2 Oak 1 3 Palm 4 Baby 4 Pine 4 Baby 5 Oak 1 6 Pine 4 7 Oak 4 Avg. 2.7 Point 7: Water than sand dune then trees 1 Pine 1 2 Pine 1 3 Pine 3 4 Pine 3 5 Pine 4 6 Pine 4 7 Oak 4 Avg. 2.9

13 Point 8: Water then very flat sand dunes 1 Oak 4 2 Pine 2 3 Pine 2 4 Pine 4 5 Pine 4 6 Pine 4 Avg. 3.3 Point 9: Smaller distance between water and sand dune 1 Oak 3 2 Oak 3 Baby 3 Pine 4 Baby 4 Pine 4 5 Pine 4 Avg. 3.6 Point 10: Smaller distance from water- not really dunes just dry sand then trees 1 Oak 1 2 Oak 1 3 Pine 2 4 Oak 2 Baby 5 Pine 4 6 Pine 4 7 Pine 4 Avg. 2.6 Excel File Type and Health Oak Palm Pine Mean Mean 3.65 Mean Standard Error Standard Error Standard Error Median 3 Median 4 Median 4 Mode 4 Mode 4 Mode 4 Standard Deviation Standard Deviation Standard Deviation Sample Variance Sample Variance Sample Variance Kurtosis Skewness Kurtosis Kurtosis Skewness Skewness

14 Range 3 Range 3 Range 3 Minimum 1 Minimum 1 Minimum 1 Maximum 4 Maximum 4 Maximum 4 Sum 65 Sum 73 Sum 89 Count 24 Count 20 Count 27 Anova: Single Factor SUMMARY Groups Count Sum Average Variance Oak Palm Pine ANOVA Source of Variation SS df MS F P-value F crit Between Groups Within Groups Total