Species Diversity Comparison North and South Slopes Betasso Preserve: Species Diversity Comparison North and South Slopes Lisa Brandt Vegetation Ecology Summer Semester 2015 University of Colorado Mountain Research Station Lisa Brandt. July 23rd, 2015. Betasso Preserve:Species Diversity Comparison North and South Slopes. Key words: Betasso Preserve, Comparison, Species Diversity.

Background Betasso Preserve Vegetation diversity Diverse landscapes Vegetation diversity North and South slopes Differences in vegetation What influences diversity between slopes? I observed that the slope dominated by Ponderosa pines faced north; Douglas pines dominated the south slope. The Ponderosa pines seemed to prefer a drier, more open habitat, with a moderate slope. Douglas firs, by contrast, grew in a shadier, cooler climate, on a much steeper slope. Contrast in understory vegetation-tall grasses, small flowers, cacti on the open area; leafy, herbaceous species in closed area, with an abundance of litter. Canopy cover was more dense on slope where Douglas firs grew.

Introduction Species diversity Environmental factors influence changes Changes occur across communities Environmental factors influence changes Slope Aspect Overstory South-facing slopes warmer, drier. (Warren, 2008) North-facing slopes cooler, more moisture Overstory influences light availability. Muller, Neufeld, and Young (as cited in Gilliam, 2007) Why is species diversity interesting? The steepness of slope affects water retention, drainage. Aspect influences amount of moisture received by community. Overstory determining factor in amount of sunlight understory receives. Other factors include soil, temperature, land-use history, human disturbances.

Question/Hypothesis I wanted to know if there is a significant difference in species diversity between north and south-facing slopes. Which slope has greater diversity? Null hypothesis There will be no difference in diversity between the two slopes Hypothesis There will be significant difference in diversity between slopes.

Methods Two sites were chosen Two different methods used Northeast-facing slope South-facing slope Two different methods used Daubenmire (for herbaceous understory) Canopy App (for woody overstory) Data collection Three separate zones chosen at main sites Three Daubenmire plots laid out in each zone Number of individual species counted Tree canopy measured as percent cover I chose these slopes due to difference in slope, and vegetation. I used Daubenmire plots to sample the number of individual species at each site. Each species was counted by stem. The number of plots used at each site helped to reduce psudoreplication, and give a truer estimate of the number of species at each site. Total of eighteen plots. A snapshot of the tree canopy at each plot was taken with the app, which then calculated the percent cover.

Results T-test species variation (H values) The p value is < 0.05, which means it is insignificant. 55% chance observed species richness occurred through a more random circumstance than what I was looking for. Richness not significantly different, but not very similar. Error may have occurred in calculation for the standard error for the south site.

Species Variation (E Values) Insignificant p value of 0.298031. Definite unevenness in species variation between sites. Error may have occurred in calculating standard error for south site.

Canopy Average Average means of canopies An average of means was done across the means for canopy cover for both sites, total of six means. The average mean for the north site was higher than the south site, indicating denser canopy cover at that site.

Jaccard Index of Similarity Similarity in species low Only 1 shared species Difference in composition South slope Ponderosa pines Tall grasses, succulents Small flowers North slope Douglas firs Low-growing, broad leaf species Low-growing shrubs Jaccard index used to determine similarities in species between slopes. Similar(not significant) species richness and evenness, different composition.The results indicate I may have to reject my original hypothesis, stating the diversity would be greater on the north-facing slope.

Discussion Difference in diversity between slopes insignificant Similar (not significant) richness, evenness Alternate hypothesis needs to be rejected Results indicate slope, canopy impact community Composition different Different zones chosen for comparison within sites More plots, sites needed for more accurate picture Northeast slope: Low-growing, broadleaf vegetation, low-growing shrubs, short grasses. Steep slope. North aspect-moisture from mountains, less sunlight. South slope:Tall grasses,succulents,small flowers. South aspect-more sunlight, more wind, less moisture.

Conclusion Other factors need to be studied Few studies include role of land use history, human disturbances. (Murphy, et al 2015) How do humans influence diversity? Questions?

References 1. Gilliam, Frank S. 2007. The ecological significance of the herbaceous layer in temperate forest ecosystems. Bioscience 57(10): 845-858. doi:10.1641/B571007 2. Murphy et al. 2015. Species associations structured by environment and land- use history promote beta-diversity in a temperate forest. Ecology 96: 705-715. http://dx.doi.org/10.1890/14-0695.1 3. Warren, Robert T. 2008. Mechanisms driving understory evergreen herb herb distributions across slope aspects as derived from landscape position. Plant Ecology 198 (2): 297-308. http://www.jstor.org/stable/40305553