In the Coronado National Forest Onamia Pope August 23, 2000
Calcareous rock is associated with distinct vegetation Other studies have correlated limestone with specific vegetation, however few studies have been done in Arizona The ocotillo appears to dominate vegetation with the presence of limestone
Is there a correlation between the presence of limestone and the abundance of ocotillo? If there is a correlation, what physical and chemical properties of limestone can explain these differences?
The site was located in the Coronado National Forest The area chosen was designed to eliminate other variable that could alter vegetation community The area had little environmental disturbance
Quantitative samples were taken from twenty-three, 25(m2) quadrants A major rock type for each quadrant was identified. The number of each dominant species of vegetation was counted. The percent of cover of rock, grasses and fairy duster was estimate by visual observation.
Latitude and Longitude data was collected using GPS Data were analyzed using chi-square statistical test and histograms
Significance level for limestone occurring with Ocotillo(.0005), Agave(.006). Significance level for limestone occurring without Fishhook cactus (.012). Non-significant results for mesquite and prickly pear occurring with limestone. No new information when tests were expanded to include limestone, granite and shale. Chi-squared test results
Differences observed in the dominance of the ocotillo are a result of physiological requirements Calcareous soils represent a more arid habitat The fine texture of limestone allows it to hold more water Limestone and granite alter the pH of the soil
Calcareous soil is a determinate of vegetation This project is in its infancy stages many factors that were not studied can cause the vegetation present. More data needs to be collected to determine over a greater time period in order to determine the effects of time on vegetation Clearly rocks are the most important thing in this world.