1. Effects of forest composition on soil nutrient concentration
Joe Persico
2018
Effects of forest composition on soil nutrient concentration
File type: pptx
Size: 8.15 MB
Keywords: Soil, essential nutrients, forest composition
Joe Persico
Winter Ecology 2018

2. Introduction
Nitrogen and phosphorus are known as the essential soil nutrients for plant growth
The concentrations of these nutrients and the processes behind them can impact a place like Niwot Ridge drastically
Differences in soils, plant species, and microbial activity can all have impacts on these concentrations
Biologists have found that certain bacteria can increase a plants uptake of soil nutrients and that increasing this uptake can increase plant growth at up to 70% (Egamberdiyeva et al., 2007)
Nitrogen can stimulate plant growth and photosynthesis in the presence of high atmospheric CO2 (Lloyd et al., 1996)
Nitrogen boosts photosynthesis, phosphorus can help plants build new tissue, As Niwot Ridge changes, warming and increase CO2 this will affect the landscape, introduce studies, as atmospheric CO2 increases will plant growth thrive?

3. Introduction
Question: How do the differences in forest composition (species/litter) affect the concentrations of nitrates and phosphorus (essential nutrients) in mountain soils? Purpose: Differences in soil nutrient levels due to differences forest composition and litter composition may affect the success of plants during growing season. These processes may give us insight into how the forest community might change in the future.

4. Introduce sites

5. Subalpine fir and Engelmann spruce
Sites
Subalpine
Elevation
~3033 meters (near C1)
Dominant species
Subalpine fir and Engelmann spruce
Soil
Covered with ice layer
Clumpy and moist but frozen
Almost no litter cover
Higher root density at surface
Diversity
Relatively high diversity, common species include subalpine fir, Engelmann spruce, quaking aspen, lodgepole pine

6. Lodgepole pine dominates this area almost completely
Sites
Lodgepole
Elevation
~2865 meters
(east of Marr Lab)
Dominant species
Lodgepole pine dominates this area almost completely
Soil
Rocky
Unfrozen
Relatively dry
Covered in litter
Diversity
Very low
Dominated by lodgepole pine

7. Methods
Located sites with different species compositions and elevations and chose three test sites within each area
Gathered soil samples and samples of any litter on top
Took measurements of soil temperature, snowpack depth, elevation, coordinates etc.
Took samples back and examined composition of both soil and litter
Used soil test kits to test for nitrate, phosphorus, and pH
Used thermometer probe
Mention frozen layer
Procedures for test kit are in the test kit
Kept soil in plastic bags frozen

8. Results p= .03755 se= (+/-) 1.44 se= (+/-) 0.8333
Introduce results and explain each graph, Ratio x:2 is ratio in comparison to site #2

9. Results
Connection between species and nutrient ratios/concentrations and correlation between phosphorus and pH

10. Discussion/Conclusion
Significant difference between the ratios of P:N at each location
Lodgepole stand show much higher nitrate concentration relative to phosphorus
Phosphorous and pH seem to have a correlation between them p=
There is a significant difference in ratios of P:N at each location with the first location having a much higher relative concentration of phosphorous. Along with this there is a correlation between the concentration of phosphorous and the soil pH value. Soil pH has been shown to correlate with nutrient uptake, more basic soils are harder for plants to take in nutrients so this may be the balancing effect.

11. Discussion/ Conclusion
Physical weathering of rocky soils in the subalpine may be the reason for higher phosphorous levels in this location (Filipelli, 2008)
Phosphorous is released through the weathering of rocks and the high root density in soils at the site may have something to do with this
Phosphorous can promote the growth of flowering plants and small shrubbery thrives off of it
Based on research, nitrogen tends to have higher concentration than phosphorous (Egamberdiyeva et al., 2007)
Physical soil differences between sites and how this may affect it,
more small shrubbery and more diverse plants in the subalpine compared to lodgepole,
Phosphorus promotes root strength and hardiness, helping small plants establish
measuring only nitrate gave a skewed view of the relative concentrations of nitrogen vs. phosphorus

12. Future studies
Taking more samples at each site and adding a site above tree-line
Looking at the summer growing season and comparing that to winter nutrient concentration
More accurate soil testing and a wider range of tests
These processes will be very important with climate change
Changes in temperature, CO2, and precipitation may change the distribution of nutrients
Changing these controls will change the way the forest is structured
This experiment should be looking at a yearly cycle with more data points
Introduce ideas to make this experiment better in the future, explain how these processes are important when looking into the future with climate change and it implications
As forests change with climate change these concentrations will be different and the cycles will change

13. References
Lloyd, J., and G. D. Farquhar. “The CO 2 Dependence of Photosynthesis, Plant Growth Responses to Elevated Atmospheric CO 2 Concentrations and Their Interaction with Soil Nutrient Status. I. General Principles and Forest Ecosystems.” Functional Ecology, vol. 10, no. 1, 1996, p. 4., doi: /
Egamberdiyeva, Dilfuza. “The Effect of Plant Growth Promoting Bacteria on Growth and Nutrient Uptake of Maize in Two Different Soils.” Applied Soil Ecology, vol. 36, no. 2-3, 2007, pp. 184–189., doi: /j.apsoil
Filippelli, G. M. “The Global Phosphorus Cycle: Past, Present, and Future.” Elements, vol. 4, no. 2, 2008, pp. 89–95., doi: /gselements