Desert Plant Relationships

Mutualistic relationship of young desert plants and nurse plants. By: Anthony J. Johnston
University of Arizona Abstract- The project being presented is on the association of desert plant life with nurse plants. It is said that desert plant life such as C. Gigantea, Ferocactus Wislizeni, and Ambrosia Deltoidea, associate themselves with other large nurse plants for protection, and other resources. Results showed that there was no random association of this hypothesis; therefore the null hypothesis is rejected.
Introduction- Plants such as C Gigantea, Ferocactus Wislizeni, Ambrosia Deltoidea, often associate themselves with nurse plants. Nurse plants are larger plants; typically with a canopy, providing other smaller plants with an establishment
The group picked an area to walk in a straight line making sure that it would not interfere with any other group’s straight line to prevent collecting the same data. Each member of every group spread out 5 meters from each of their own group members still making sure not to intersect with another group. In a line, the group moved forward in a straight line, counting the numbers of each juvenile C Gigantea, Ferocactus Wislizeni, and Ambrosia Deltoidea that were associated with nurse plants and those that were not. We determined whether each species was juvenile or not by measuring each to see whether it was 30’ or under. For each one found the group members recorded it down tallying them all up as they went along. All the groups came together comparing and sharing data to get total numbers of each species. One group calculated the percent coverage, which would then be used to calculate the chi squared ((obs.-exp.) ^2/ exp.)
Results- C Gigantea observed in association with nurse plants (53) added to the total number of C Gigantea observed that were not in association with nurse plants (38) got us the total observed, which is 91. Preforming the chi squared test resulted in that there is not random association among C. Gigantea and nurse
In each one of the categories of species you can see clearly that each by preforming chi squared end up with 1 degree of freedom and each of the probabilities on the chi squared distribution chart. As each number rises in the degree of freedom and the probability you know that you’re null hypothesis or the random distribution of desert plant animals is becoming less likely to be true. Therefore that means that the evidence is supporting the alternative hypothesis. This type of mutualism between the C. Gigantea, Ferocactus Wislizeni, Ambrosia Deltoidea and the nurse plants like the Palo Verde tree is a perfect example of how an ecosystem works. (Ecology) The distribution of organisms is a defining feature of how and ecosystem actually works. A relationship of this kind provides many benefits such as “increased nutrients, lower summer soil temperatures, reduced evapotranspiration, and protection from animals” (Tally D Drenzer, Coleen M. Garrity (2003) “Saguaro Distribution under Nurse Plants in Arizona’s Sonoran Desert: Directional and Microclimate Influences pg. 1). “Many saguaros perish from freezing winter temperatures and from desiccation in the summer when only saguaros under a nurse survive” (T. D. Drenzer; Volume 65, Issue 1, April 2006, Pages 46–61, Plant facilitation in extreme environments: The non-random distribution of saguaro cacti (Carnegiea gigantea)