All posts by Sara F

Research Example #5: The Effects of Conifer Encroachment and Overstory Structure on Fuels and Fire in an Oak Woodland Landscape

 

Engber, Eamon A.,  J.M. Varner, III, Leonel A. Arguello, and Neil G. Sugihara

A study conducted in the Bald Hills of Redwood National Park, California, USA, looked at the influence of overstory structure on fire intensity and fuels in oak dominated woodlands and savannas. Three sites that were prioritized for prescribed burns in 2008 and 2009 were the burn sites for the study. Site one had been burned five times since 1991, while sites two and three had been burned three times since then. It is important to note that grazing has also taken place on this land, sites one and two were grazed up until 1980, and site three was grazed until the year 1991, the year that particular site was added to Redwood National Park. Burn units were systematically split up into five categories of grassland, oak savanna, oak cluster, oak woodland, and invaded woodland based on their probable fuel structure and composition. Plots were then randomly selected for analysis. Fuels were sampled in four grades of leaf litter, woody material, combined live and dead herbaceous material, and shrub surface fuels.

Sampling of sites one and two were done in August of 2008, while sampling for site three was done in August of 2009. No sites were re-sampled. Prescribed burns were administered by Redwood National Park managers in the autumn of 2008. Sites one and two were burned in the autumn of 2008, however site three, which was scheduled to be burned in the autumn of 2009, could not be burned due to poor weather conditions.

Data needed for this study was behavioral because the forest ecologists were determining how encroachment of conifers affected the forest floor. This is just observing the tree’s behavior. Data was analyzed by running ANOVA tests on all of the different elements of the study. The largest differences in fuelbed were between grasslands and invaded woodlands, at opposite ends of the spectrum. Grasslands had heavier herbaceous mass and lower fuel moisture, while invaded woodlands were just the opposite. The invaded woodland sites had much more woody fuel, and lower herbaceous mass, resulting in lower community flammability. This suggests greater overstory shading and development of forest floors with denser woody material is somewhat responsible for less frequent fire.
Engber, Eamon A.,  J.M. Varner, III, Leonel A. Arguello, and Neil G. Sugihara. “The Effects of Conifer Encroachment and Overstory Structure on Fuels and Fire in an Oak Woodland Landscape.” Fire Ecology 7.2 (2011): 32-50. Agricola. Web. 22 Mar. 2017.

Prescribed fire mortality of Sierra Nevada mixed conifer tree species: effects of crown damage and forest floor combustion

Scott L. Stephens and Mark A. Finney

A total of 1025 trees were analyzed in a study of white fir, sugar pine, ponderosa pine, black oak, incense-cedar, and giant sequoia. These trees were analyzed to find out how they would be affected by a prescribed fire. Indicators that were measured included the diameter of the tree (DBH), the percent of the crown that was scorched, along with the height it was scorched at, and the amount of the forest floor that was consumed by the fire. It was found that these indicators were not significant for predicting the death of black oak. The indicators did conclude however that death rates were lower for giant sequoia, incense-cedar, and ponderosa pine than the other species measured. It was also found that consumption of life on the forest floor is a good indicator of morality in most species.

Data needed for this study was behavioral because the forest ecologists were determining how oaks and other species responded in levels of morality to a disturbance in surroundings. This is simply observing the tree’s behavior, but can be confusing because you are not testing human subjects. Data was collected by measuring four indicators of the tree’s overall health. Data was analyzed by running regression models for four different species, although there was no pre-burn data for the forest floor of the giant sequoias measured.

Stephens, Scott L., and Mark A. Finney. “Prescribed fire mortality of Sierra Nevada mixed conifer tree species: effects of crown damage and forest floor combustion.” Forest Ecology and Management 162.2 (2002): 261-271.

Enhancing community based forest resource management vital to local livelihoods in the Lower part of Mekong Basin

sydney.edu.au/mekong/documents/current_projects/mli_partnerinit_nuolkkuexchange_proposal_jan06.pdf

This research proposal is called Enhancing community based forest resource management vital to local livelihoods in the Lower part of Mekong Basin and was conducted by Somsy Gnophanxay, Lamphoun Phanvongsa, and Dr. Buapun Promphakping.

These researchers planned to establish more efficient ways for professors in Laos and Thailand to conduct research and fieldwork with students to improve the Mekong Learning Initiative. They planned to do this to improve forest health in Laos and Thailand because forest degradation in both countries is a large concern.

The research proposal is set up in an odd way, the researchers didn’t have a question, but rather objectives and expected results. Although they called this a research proposal, and they went through with this plan, it’s not a traditional research proposal because it’s missing so many things. With the lack of their research question, they don’t have a specific type of data they set out to collect, and from there the entire project gets disorganized. The first thing the do in the proposal is define where the data collection site will be, Step 5 in the design to data analysis. After this they set up their structure for methods and implementation, which again is not as clear as it should be. The writers of this proposal spend a lot of time discussing the background of forest degradation in Thailand and Laos for how uncentered their project is. Reading the background made me think there was going to be a lot more focus on environmental issues rather than researching how people can better understand this through collaborative learning. Although it can be inferred from reading the entire proposal, the data type or collection method is not outlined in any clear way. This proposal clearly has a lot of room for improvement and hopefully this example of a not so thorough research proposal can help students to design much clearer versions of their own research in the future.

Research Exercise #2: Restoration release of overtopped Oregon white oak increases 10-year growth and acorn production

Warren D. Devine, Constance A. Harrington

In the Willamette Valley area of the Cascade mountain range in the Pacific Northwest region of the United States there have been high levels of encroachment of Douglas-fir (Pseudotsuga menziesii) on Oregon white oak (Quercus garryana). These savanna and woodland areas were historically kept-up by frequent burns, usually caused by humans for many reasons. Oaks typically need direct sunlight to photosynthesize, so encroachment of Douglas-firs that have been overtopping oaks has caused oaks to live in suppression for decades, which hinders biodiversity, lifespan of the oaks, and the amount of acorns they produce. This study looks at how oaks respond over ten years to the invasion of Douglas-firs being removed. There were four different methods of release measured: Full release, or full removal of douglas firs in a plot, half release, thin only, and control in which there was no removal. Growth of oaks in plots where full removal of Douglas-firs was done was significantly greater than in plots where other treatments were done. Acorn production was also handily influenced by full removal of Douglas-firs, however, height and crown area growth was not influenced. Acorn production in thinned and half released plots also improved, but not as high as full release areas. Treatments indicated that removal of encroaching fir trees highly influenced oaks to grow rapidly and oaks showed no negative effects due to a dramatic change in environment.

Data needed for this study was behavioral because the forest ecologists were determining how oaks responded in growth to a change in surroundings. This is simply observing the tree’s behavior, but can be confusing because you are not testing human subjects. Data was collected by measuring plots that had 18 oak trees each with a wide range of DBH (diameter at breast height) with varying degrees of suppression. Data was analysed by a generalized, randomized, complete-block design analysis of variance (ANOVA) model. The experimental unit was the center oak of the plot.

Devine, W. D., & Harrington, C. A. (2013). Restoration release of overtopped Oregon white oak increases 10-year growth and acorn production. Forest Ecology & Management, 29187-95. doi:10.1016/j.foreco.2012.10.053

Research Exercise #1: Post-Fire Recovery of Acorn Production by Four Oak Species in Southern Ridge Sandhill Association in South-Central Florida

Post-Fire Recovery of Acorn Production by Four Oak Species in Southern Ridge Sandhill Association in South-Central Florida

Warren G. Abrahamson and James N. Layne

Two components of research were done in this study. Both the amount of stems that grew acorns and the number of acorns produced were examined. Four types of oaks were being tested, two white oak species, and two red oak species. Counts of both of these were taken yearly from 1969 to 1998 on two 2.7 hectare plots. The prescribed burn took place in May of 1993 on one of the plots. Both species of white oak produced acorns the year after the fire, although not as many as years before the fire, although five years after the fire, began producing more acorns than years before the fire. Red oak species took 3-4 years to begin producing acorns again, although there were no remarkable differences after they began producing again. The amount of acorns produced along with the timing of production both have the potential to heavily influence the biodiversity of the area because birds, mammals and insects which eat the acorns are all affected as well as the species they interact with.

Data needed for this study is observational because the researchers are observing a behavior of a species before and after a variable is changed. Data gathering came from walking the grid of both the control plot (unburned) and the burned plot and counting each checkpoint tree for sufficiently developed acorns. Counting acorns on taller trees was almost certainly less accurate than most oaks, but a long bamboo pole was used to move branches around for visibility. Data analysis was all done by purely counting what had been produced compared to years before.  

Abrahamson, Warren G., and James N. Layne. “Post-Fire Recovery of Acorn Production by Four Oak Species in Southern Ridge Sandhill Association in South-Central Florida.” American Journal of Botany, vol. 89, no. 1, 2002, pp. 119–123. www.jstor.org/stable/4131345.

 

Journal Exercise #2: Influence of recent bark beetle outbreak on fire severity and postfire tree regeneration in montane Douglas-fir forests

Influence of recent bark beetle outbreak on fire severity and postfire tree regeneration in montane Douglas-fir forests

Brian J. Harvey, Daniel C. Donato, William H. Romme, and Monica G. Turner

This study was conducted to asses the impact bark beetles has on wildfires and how quickly they spread along with tree regeneration after the fire had occurred. These researchers looked at the Gunbarrel fire of 2008, which took out 27,000 hectares of Douglas-fir (pseudotsuga menzeisii) dominant wilderness. This area experienced a bark beetle outbreak 4-13 years before the fire occurred and the majority of the trees were dead or dying with their needles dropped. There were 85 plots sampled for stand structure pre-fire and severity of bark beetle outbreak. It was found that fire severity was directly correlated with topography and burning conditions. Regeneration of Douglas-firs after the fire was low with no tree seedlings in 65% of plots. Tree seedlings were abundant in plots with low fire severity that also had low outbreaks of bark beetles. There is no link between the severity of burn and outbreak of bark beetles, but together they have high disturbance level.

To answer these questions about Douglas-fir populations in lower mountainous regions, researchers had to use reports of acts, behaviors, and events because they are looking at the behaviors of species in relation to a disease and fire.

To conduct this study, 85 plots were sampled in the mid Rocky mountain eco-region. Plot samples began in 1995 to measure bark beetle outbreaks and peaked in the early 2000’s. Most trees (98.5%) were killed by bark beetles before the fire began. To sample plots, bark was tested from every tree taller than 1.4 m and analyzed using Spearman’s rank correlation test between each quantitative metric of fire severity and beetle-killed area in all plots.

Harvey, Brian J., et al. “Influence of recent bark beetle outbreak on fire severity and postfire tree regeneration in montane Douglas‐fir forests.” Ecology 94.11 (2013): 2475-2486.

Journal #1

Tree recruitment in relation to climate and fire in northern Mexico

Jed Meunier, Peter M. Brown, William Romme.

Over the past decades, forest structure in mountainous regions have changed due to factors such as anthropogenic disturbance, varying climate, species competition, and changes in the way we use land. This article looks closely at how fire, climate, and tree recruitment* interact with these factors in the Sierra San Luis mountains of northern Mexico. Researchers found that fires are closely related to wet-dry climate cycles where the climate will go through periods of drought and periods of wet conditions. The greatest times of tree recruitment were tied to a mid-century drought and low fire frequency and also in fireless periods with low precipitation levels.

To answer these questions about tree populations in northern Mexico, researchers had to use demographic data because they were describing characteristics of a population, although it was a forest population and trees rather than people were being described and analyzed through tree-coring.

This data was collected by sampling 30 plots among 3 sampling sites in Ponderosa Pine dominant wilderness which included pinyon pines and Chihuahua pines. Plot sizes ranged from .04 hectares to .37 hectares. Data analysis was completed using spatial analysis tools such as GIS.

From reading this study, I think the research was done quite well although there is a wide range of plot sizes. I wonder if the research would have been more consistent if they had sed the same plot measurement for each tested plot, however that does not take into account landscape changes that researchers likely had to deal with.

*recruitment occurs when juvenile organisms survive to be added to the population to a stage where organisms are settled.

MEUNIER, JED, PETER M. BROWN, and WILLIAM H. ROMME. “Tree Recruitment In Relation To Climate And Fire In Northern Mexico.” Ecology 95.1 (2014): 197-209