Pausas et al. (2009) said that wildfires have shaped plants and their defenses against fire before humans emerged. With that said wildfires play a key role in ecosystem conservation. The effects of fires biodiversity have not been as completely studied as many believe. Some species of plants in the Southern California Chaparral depend on fire to increase the rate of germination in a burned area. Other plants in the Southern California Chaparral rely on the wind or animals to bring their seeds into a burned area to germinate. The Orange County Fire Authority Board of Directors, Freeway Complex Fire After Action Report (2009) detailed about the fire being investigated. The fire which is being investigated is the Freeway Complex Fire which started on November 15, 2008 and was contained on November 19, 2008. The Fire affected the following cities of Southern California: Anaheim, Brea, Corona, Chino Hills, Diamond Bar, and Yorba Linda. The hypothesis being tested is there will be a statistical difference in the number of specific plant species and there Importance Value when compared to a burned and unburned area.
Methods and Materials
The area selected to collect data was for this experiment was a location in Diamond Bar, California along the Brea Ridge Motorway; along a 400 meter portion of the Freeway Complex Fire. The data was collected on October 9, 2009 starting at 10:00 am till 2:00pm and October 23, 2009 at 9:30 am till 4:30 pm. The method used to collect the data was point-quarter sampling. There were a total of ten transect. Five at 100 meter intervals, measured with a 100 meter transect tape, which went into the burn area. Then another five at 100 meter intervals, measured with a 100 meter transect tape, which went into the unburned area. Each transect was 100 meter and measured with a 100 meter transect tape. Data was then collected in 20 meter points along the transect tape. Each point represented the center of the measurement area. Then from the center, a compass was used to define four quadrants (Northwest, Northeast, Southwest, and Southeast). In each quadrant the closest plant’s stem or clump of stem’s to the center of the point was measured (point to plant) and recorded using a 30 meter transect tape. The diameter of the plant was then measured using a 30 meter transect tape. Finally the species of the plant was recorded. This process was repeated for each transect.
All data was then transferred to MS Excel (Microsoft Corporation, Redmond, Washington). The data was first statistically analyzed using the Simpson’s Diversity Index:
Where n equals the total number of a particular species, and N equals the total number of all species. The value D ranges between 0 and 1; 1 represents infinite diversity and 0 represents no diversity.
The data was then manipulated algebraically to determine Importance Value (IV) as referenced by Krebs. (2001) IV is the sum of the Relative Density, Relative Frequency, and Relative Coverage. Then all IV were analyzed using an ANOVA: Single Factor to determine significant difference in IV.
The following plants were found in both the burned area and unburned area were: Lotus scoparius (Deerweed), Rhus integrifolia (Lemonade Berry), Phacelia cicutaria (Caterpillar Phacelia), Salvia mellifera (Black Sage), Toxicodendron diversilobum (Poisonoak), and Gnaphalium canescens (Fragrant Everlasting), Adenostoma fasciculatum (Chamise), Malosma laurina (Laurel Sumac), Wyethia ovate (Southern Mule Ears), Eremocarpus setigerus (Turkey Mullein), Baccharis salicifolia (Mule's Fat). The study found there was a significant difference in plant species and their population when compared to an area that had burned approximately one year ago to date; using the Simpsons Diversity Index (D = 0.89968). Figure-1 shows the Diversity of plant populations in the burned area compared to the unburned area.
There is a significant difference in number of plant species when compared to an area that had burned approximately one year ago to date; using the Simpsons Diversity Index (D
The six species of plants that had the highest frequency were: Deerweed, Lemonade Berry
, Caterpillar Phacelia, Black Sage, Poison Oak, and Fragrant Everlasting. The mean Importance Value (IV) for Deerweed in the burned area was 1.055 ± 0.203 (±SEM, N=5) compared to the mean IV of Deerweed in the unburned areas was 0.035 ±0.035 (±SEM, N=5). The mean IV for Lemonade Berry in the burned area was 0.161 ±0.068 (±SEM, N=5), compared to the mean IV of Lemonade Berry in the unburned area was 1.204 ± 0.291 (±SEM, N=5). The mean IV of Caterpillar Phacelia found in the burned area was 0.285 ± 0.153 (±SEM, N=5), compared to the mean IV of Caterpillar Phacelia in the unburned area was 0.0464 ± 0.046 (±SEM, N=5). The mean IV of Black sage found in the burn area was 0.550 ± 0.155 (±SEM, N=5), compared to the mean IV of Black Sage found in the unburned area was 0.055 ± 0.034 (±SEM, N=5). The mean IV for Poison Oak in the Burned area was 0.084 ± 0.053 (±SEM, N=5), compared to the mean IV of Poison Oak found in the unburned area was 0.245 ± 0.181 (±SEM, N=5). The mean IV of Fragrant Everlasting found in the burned area was 0.210 ± 0.183 (±SEM, N=5), compared to the mean IV of Fragrant Everlasting found in the unburned area was 0.710 ± 0.219 (±SEM, N=5).
There was a statistical difference in IV’s of all the species of plants found in the burned area compared to the same species of plants found in the unburned area (p=8.677x10-9, ANOVA). Upon running the Bonferroni correction, the difference was between the IV of Lemonade Berry in the burned versus the unburned area (5.24%). There was also a difference in IV of Deerweed in the burned versus the unburned area (5.13%). Figure-2 represents the difference in IV of the six most frequently found plants in the burned area when compared to the plants found in the unburned area.
Mean Importance Values (IV) with standard error of species found in a burned area compared to species found in an unburned area (N=5).There was a statistical difference in IV’s of the all species found in the burned area compared to the all species found in the unburned area (p=8.677x10-9
Lloret et al. (1991) researched Rhus integrifolia (Lemonade Berry) and found that the majority of the recovery of this plant in the burned chaparral was due to Peromyscus californicus and Neotoma fuscipes. The animals would eat the fruit of the Lemonade Berry and then while in the burned chaparral would release the fecal waste, transporting the seeds of the Lemonade Berry into the burned area so it has the possibility of germinating. Lemonade Berry bares its fruit in spring and well into summer. This could account for the relatively low Importance Value of Lemonade Berry plants found in the burned area; considering they have had one growing season to recover.
Montalvo and Ellstrand (2000) researched how to advance the growth and spread of Lotus scoparius (Deerweed). There data suggest that success rates will be higher if genetically or environmentally similar populations are used to supply seeds for restoration and post-fire seeding of specific sites. With their research this may account for the Deerweed having the highest IV, when ranked, in the burned area when compared to the rest of the species found in the Burned area.
Keeley (1991) found that heat plus charred wood had a synergistic effect on percentage of germination of Phacelia cicutaria (Caterpillar Phacelia), over charred wood alone. Although there was not a statistical difference in IV of Caterpillar Phacelia; this may account for why there was more Caterpillar Phacelia found in the burned than unburned area. This was also the case with another research project. Monroe et al. (1991) researched two shrub species native to Southern California which showed different germination patterns in relation to fire intensity. Adenostoma had enhanced germination in the control burn; however, as fire intensity increased, germination decreased. In contrast, while Ceanothus was also stimulated by the heat of the control burn, it had a significantly much greater germination as fire intensity increased in the treatment, decreasing only in the most intense treatment (controlled burn).
A special thanks to Nicole Barret who assisted in collecting data and entering data into MS Excel.
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