Is there a relationship between Saguaro Height and Arm Growth?

Background Info  In Saguaro National Park, for example, saguaros begin to grow arms at about 65 to 75 years of age. Since the flowers grow at the ends of the main trunk and arms, additional arms allow the saguaro to produce extra flowers.

Where, How, Why?  Where do saguaros grow?  Saguaros, Carnegiea gigantea, grow in most parts of the sonoran desert. They are generally found growing between sea level and 4,000 ft. of elevation.

How do Saguaros Grow?  Saguaros are very Slow growing. They usually grow about ” in the first 8 years of life.  Saguaros arms or branches typically begin to appear around years of age.  They begin to grow flowers at about 35 years old.

Why are Saguaros Pleated?  The roots of a saguaro grow in a radial fashion.  During rainfall, the roots will absorb as much water as possible.  To accommodate this large influx of water, the pleats expand like an accordion.Conversely, the pleats contract in dryer weather.  Saguaros can weigh up to 6 tons!

Baby Saguaros  For the best chance of survival, saguaro seedlings need the protective cover of a "nurse plant". The shade and additional moisture under the nurse plant is crucial to the survival of young saguaros.

More Info …  While most saguaro cacti grow in a typical fashion, a few individuals will grow in an atypical form known as a cristate or “ crested saguaro ”. These bizarre looking forms often grow as a crest, but may also take other shapes such as balls or simply grotesque blobs.

Hypothesis  Our hypothesis is:  That Saguaros above 10 feet will have at least one arm growth.

Null Hypothesis  Our null hypothesis:  A null hypothesis will result if it is determined using Chi Square values that there is no relationship between saguaro height and arm growth.

Data Collection  We collected 100 samples of data in the Sonoran desert and found the following:  For saguaros about 10 feet tall-  64 had arms  36 had no arms

Data Interpretation  We used the Chi Square statistical test and our calculations to determine if there was a null and an alternative hypothesis.

Results Table 1: Correlation between Saguaro Arm Growth and Saguaro Height Degree of Freedom= 1 P= 0.05 = 3.84 Saguaro Cactus (appx. 10ft tall) ObservedExpected (Observed/ Expected) 2 Expected Calculations Associated (with arms) 6750 (67-50) 2 /67= /67= = X 2 = 13.1 Non- associated (w/o arms) 3350 (33/50) 2 / 33= /33= = X 2 = 13.1

Results Explanation  It is shown that X 2 equals Since the X 2 value exceeds the critical value in column P= 0.05, which is 3.84, one can see that there is a significant correlation between Saguaro arm growth and the height of Saguaros.

Conclusion  We Reject our null hypothesis which was determined using X 2. Because the X 2 value of 13.1 is greater than the critical value, then there is a relationship between Saguaro height and arm growth.  We accept our alternative hypothesis.