Impact of Convex and Concave Slopes on Alpine Vegetation

1. Effects of Convex and Concave slopes on Vegetation Characteristics Joe Persico

2. Introduction/Background • Question: How could convex and concave slopes (both north and south) affect vegetation and soil characteristics in the high alpine? • This may change the way that water flows from snowmelt and drainage and can help us understand the dynamics of this ecosystem (Aandahl, 1949) • Looking at north and south facing slopes as well to • affects the landscape on a larger scale • J.E Pinder III worked in Lassen Volcanic National Park

3. Site Description #1 • Just above cable gate near our alpine field day site. • South west of Niwot Mountain • South facing slope with both a concave and convex section • Just above treeline • Mostly small herbaceous vegetation with some willows and Krummholz • Slope aspect: 150° S-SE • Slope Angle: 9° • Coordinates: 40°03'04.0"N 105°35'04.7"W

4. Site Description #2 • Above Cable Gate and over Niwot Ridge • Northwest facing slope • Northwest of Niwot Mountain and just below • Just above treeline with small Krummholz creeping in • Concave and convex sections of the slope • Mostly small herbaceous vegetation with some Krummholz and willows • Slope Aspect: 320° N-NW • Slope Angle: 6-8° • Coordinates: 40°03'13.9"N 105°34'38.0"W

5. Methods • Walked past cable gate a south facing and north facing slope with concave and convex sections • Each convex or concave section set a 30m transect perpendicular to the aspect of the slope • Record the angle and distance to center for concave and convex slopes • Each transect had 3 Daubenmire plots • Small sample of soil at each site at depth 10cm was taken • Line intercept method was also used along each transect within each plot • Steps repeated along transects on our North facing slope • Data recorded and analyzed Anova-with replication and chi-squared

6. Results/Figures

7. Results/Figures

8. Results/Figures

9. Results/Figures

10. Conclusions • Significant difference in moss and lichen frequency between concave and convex slopes • Graminoids do not show a significant difference in frequency • Obvious differences in cover type • Observationally more barren on convex slopes • Not much difference between north and south facing • Soils showed little differences (dry vs. wet) • Steepness and angle create differences

11. Conclusions and Discussion • Percent cover shows significant difference in terms of moss and lichen • Also shows significant difference in graminoid cover between convex and concave • More water loving plants reside in concave landscapes (Bridge and Johnson, 2009) • Wind rain and other disturbances discourage plants from colonizing in convex slopes • Concave have more protection from stressors (Gilbert, 1909) • Affects water runoff and fire patterns in the alpine regions (Pinder, et al., 1997) • Soils are drier and more prone to runoff on convex slopes

13. Works cited • Sakai, A. & Ohsawa, “Vegetation pattern and microtopography on a landslide scar of Mt Kiyosumi, central Japan.” M. Ecol. Res. (1993) 8: Issue 1 pp.47-56. https://doi.org/10.1007/BF02348606 • Aandahl, Andrew R. “The Characterization of Slope Positions and Their Influence on the Total Nitrogen Content of a Few Virgin Soils of Western Iowa1.” Soil Science Society of America Journal, vol. 13, no. C, (1949) p. 449., doi:10.2136/sssaj1949.036159950013000c0081x. • Bridge, S.r.j. and E.a. Johnson. “Geomorphic Principles of Terrain Organization and Vegetation Gradients.” Journal of Vegetation Science, vol. 11, no. 1, (2000) pp. 57–70., doi:10.2307/3236776. • Iii, J. E. Pinder, G. C. Kroh, J. D. White and A. M. Basham May, “The Relationships between Vegetation Type and Topography in Lassen Volcanic National Park.” Plant Ecology Formerly `Vegetation', vol. 131, no. 1, (1997) pp. 17–29., doi:10.1023/a:1009792123571. • Gilbert, G. K. “The Convexity of Hilltops.” The Journal of Geology, vol. 17, no. 4, (1909) pp. 344–350., doi:10.1086/621620.