1. Environmental Studies with an emphasis in Biology
Sex Distribution and Energy Allocation of Dioecious Juniperus virginiana Along an Environmental Gradient.
Taylor Sloey
Undergraduate Thesis
Environmental Studies with an emphasis in Biology

2. I. Background
II. Introduction
III. Materials and Methods
IV. Results
V. Discussion
VI. Conclusion

3. Eastern Red Cedar (Juniperus virginiana)
I. Background
Eastern Red Cedar (Juniperus virginiana)
+ Abundance and Distribution Across United States (Fowels, 1965, Boyce, 1954)
+ Essential Environmental Nutrients
+ Dioecious plants
- Fertilization
- Energy allocation to seed production
Seed production more costly
More limited in nutrient poor/ stressful environments
(Meagher, 1981)
Seed production less costly
Less limited in nutrient poor/ stressful environments

4. I. Background
Environmental Gradient
A productivity gradient due to the richness of essential elements and nutrients (Adkinson and Gleeson, 2004)
+ Nutrient Availability
- Carbon, Nitrogen, Phosphorous
+ Solar Availability
- Shading and Crowding, Daytime
+ Water Availability
+ Effect of Ground Slope
+ Energy Tradeoff
-Growth vs. Reproduction

5. Canyon at Cedar Point Biological Research Station in Ogallala, NE
II. Introduction
Canyon at Cedar Point Biological Research Station in Ogallala, NE
Presumed nutrient and element variance of canyon. N N
Desiccating Sunlight
Steeper Slope N N N E N W N N N N N N N N N N N

6. Presumed Sex Distribution
II. Introduction
Presumed Sex Distribution
Biased sex ratios can result under manipulation of essential resources (Guillon and Raquin, 2002). N N N N N E N W N N N N N N N N N N N

7. Hypothesis
There is a correlation between distribution of sexes and nutrient availability and environmental elements. This will be made evidenced by a lower frequency of female individuals in environmentally poor areas. Also, females will have smaller average diameters on average than males.
Quantified by Nitrogen and Carbon ratios in:
1. Plant tissue- which indicate both nutrient limitation and nitrogen saturation experienced by that individual (Tessier and Raynal, 2003).
2. Soil samples- which indicate environmental nutrient availability to the individual.

8. III. Materials and Methods Initial Sample:
6 transects 20m across expanding from East to West hillsides
987 trees individually numbered and tagged
Data Collected: Location in transect, sex, aspect, degree of ground slope, diameter at six inches above ground.
Quadrat
Transect
East Hilltop Valley West Hilltop

9. III. Materials and Methods

10. III. Materials and Methods
Subset Selection
101 trees equally representative of sex, side, and location.
Data Collected
Soil & Leaf Tissue
- Dried
- Pulverized
- Processed in CHNSO Elemental Combustion Analyzer
Analyzed for carbon and nitrogen

11. IV. Results
•General Environmental Gradient Qualities
•Variation in Diameter Along an Environmental Gradient in Relation to Sex
• Distribution of Sexes Along an Environmental Gradient
• Variation in Leaf Nutrients of Each Sex Along an Environmental Gradient
• Variation in Soil Nutrients of Each Sex Along an Environmental Gradient

12. I
IV. Results
•General Environmental Gradient Qualities

13. IV. Results
•General Environmental Gradient Qualities

14. IV. Results
•Variation in Diameter Along an Environmental Gradient in Relation to Sex
Features of importance to diameter: aspect, transect, side*sex
Transect

15. Trees have not been aged.I
IV. Results
•Variation in Diameter Along an Environmental Gradient in Relation to Sex
IMPORTANT!
Trees have not been aged.

16. IV. Results
• Distribution of Sexes Along an Environmental Gradient
EAST: The sexes grew at relatively equal frequencies.
WEST: Dominated by males relative to females.
East F M
West F M

17. IV. Results
•Variation in Leaf Nutrients of Each Sex Along an Environmental Gradient

18. IV. Results
•Variation in Leaf Nutrients of Each Sex Along an Environmental Gradient

19. IV. Results
•Variation in Leaf Nutrients of Each Sex Along an Environmental Gradient

20. IV. Results
•Variation in Leaf Nutrients of Each Sex Along an Environmental Gradient
Difference of carbon in leaf tissue did not differ greatly enough to be biologically significant to the trees’ growth or survival.

21. IV. Results
• Variation in Soil Nutrients of Each Sex Along an Environmental Gradient

22. IV. Results
• Variation in Soil Nutrients of Each Sex Along an Environmental Gradient

23. IV. Results
• Variation in Soil Nutrients of Each Sex Along an Environmental Gradient

24. IV. Results
•Variation in Soil Nutrients of Each Sex Along an Environmental Gradient
Difference of carbon in soil did not differ greatly enough to be biologically significant to the trees’ growth or survival.

25. V. Discussion
•Main Results
In accordance with the hypothesis: Female trees exhibited slightly higher nitrogen levels in leaf tissue on average. Although the difference was slight, and likely not biologically significant.
Position in the canyon transect appeared to be a larger influence on sex ratio and diameter than nitrogen or carbon.

26. V. Discussion
•Variation in Diameter Along Gradient in Relation to Sex
+ Female on West > Females on East.
• Assuming the West was not as desiccating as the East, it appears females can allocate more energy to vegetative growth in less stressful environments.
+ Males on East > Females on East
• Females struggle to allocate energy to vegetative growth under stressful environments.
+ Males on the West < Males on East.
This could be a result of spatial crowding.
Note: Trees have not yet been aged.

27. V. Discussion
•Distribution of Sexes Along an Environmental Gradient
Side of the canyon appeared to have most influence.
East = Sexes occurred at equal frequency
West = Males occurred at higher frequency
• Perhaps females are limited on the West due to the steeper slope and nutrient leaching.
• Males may outnumber females as they are better competitors. E W N

28. V. Discussion
•Variation in Leaf Nutrients of Each Sex Along an Environmental Gradient
• Higher levels of nitrogen in leaf tissue indicate the plant’s access to essential nutrients and ability to assimilate nitrogen for growth.
• Females had slightly higher levels of N in tissue compared to males, in correspondence with the hypothesis, however, this was not a significant difference.
• Carbon level was slightly higher in males, indicating that males may be able to allocate more carbon to non-reproductive growth. However, this was not a significant difference.
• N and C levels were slightly higher in trees on the East than the West. While this is not a significant difference, it may be due to nutrient leaching.

29. V. Discussion
•Variation in Soil of Each Sex Along an Environmental Gradient
• Higher levels of C and N in soil indicate nutrient rich areas.
• C and N in soil did not differ significantly between sexes or side of canyon.
• Therefore, soil nutrients did not influence sex ratios.

30. Hypotheses: VI. Conclusion
• The survival and fecundity of female Juniperus virginiana is lower in relatively nutrient poor environments. Not Supported
• Males had a larger average trunk diameter than females Supported (on East side), trees were not aged.
The fact that female trees were larger on the West side of the canyon supports the notion that stress, more specifically, water stress, may be affecting female growth on the more desiccate East side.
• Side of canyon appeared to influence sex distribution more than any other factor.
• Future Application….

31. Edna and William Linder Fund
Special Thanks to…
Dr. Diana Pilson
Dr. Sabrina Russo
Dr. Jean Knops
Dr. David Gosselin
Sara Yendra
Jake Arneson
UNL UCARE
J. Ve. Srb Memorial Fund
Edna and William Linder Fund

32. Works Cited:
Adkinson, Greg P., and Scott K. Gleeson Forest Understory Vegetation along a Productivity Gradient. Journal of the Torrey Botanical Society, Vol. 131, No.1, pp
Boyce, S.G The Salt Spray Community. Ecological Monographs Vol. 24, pp
Fowells, H.A Silvics of Forest Trees of the United States. USDA Forest Service, Agr. Handbook No. 271, pp U.S. Govt. Printing Office, Washington, D.C.
Guillon, Jean-Michel, and Christian Raquin Environmental Sex Determination in the Genus Equisetum: Sugars Induced Male Sex Expression in Cultured Gametophytes. International Journal of Plant Sciences, Vol. 163, No.5, pp
Meagher, T.R Population biology of Chamaelirium luteum, a dioecious lily. II. Mechanisms governing sex ratios. Evolution 35:
Tessier, Jack T., and Dudley J Raynal State University of New York College of Environmental Science and Forestry. Journal of Applied Ecology. Vol.40, pp