1. Do Saguaros Grow Older in Higher Elevations?
Erin Benjamin
Brian Block

2. Elevation Effect on Saguaro Growth
Importance
- Saguaros are losing habitat
- Humans are developing further into the desert
- Conservation
- To improve knowledge on how and where to conserve the saguaro species

3. Elevation Effect on Saguaro Growth
Hypothesis: Saguaros Grow Better at Higher Elevation
Criteria to be Measured
Number of Arms
Older Saguaros Have a Greater Number of Arms

4. Elevation Effect on Saguaro Growth
Background
- Saguaros have a slow growth rate
- Saguaros have a shallow root system and are less able to tolerate extended periods of drought
- Saguaros are not frost resistant
- The older a saguaro the more arms (Saguaros over 200 years old routinely have 5 or more arms)

5. Elevation Effect on Saguaro Growth
Background - Environmental Variables
- The higher the elevation the cooler the temperature
- The lower the elevation the lower the amount of moisture in the air
- The higher the elevation the stronger the intensity of the sun
- The higher the elevation the colder the winters and the higher the chance of saguaro death
- The higher the elevation the more rain the monsoon season brings

6. Elevation Effect on Saguaro Growth
Methods
Two Investigators Examined 200 Saguaros and Counted Arms in Separate Geographic Locations
Locations Examined
Apache Junction Elevation 1758 Feet
Catalina Foothills Elevation 2559 Feet
Data Compiled and Evaluated

7. Catalina Foothills Elevation 2559 Feet

8. Apache Junction Elevation 1758 Feet

10. Results Catalina Foothills 6% of cacti observed had 10 arms or more
Apache Junction 38% of cacti observed had 10 arms or more
Based on Hypothesis there is a greater percentage of older saguaros at lower elevation examined

11. Saguaros grow better at lower elevations
Results
Reject Hypothesis
Create New Hypothesis
Saguaros grow better at lower elevations

12. Overview Cooler temperatures effect growth rate
The intensity of the sun effects saguaros growth
Colder winters lead to saguaro death

13. Study Limitations Data compiled from different regions
Only one investigator counted saguaros with no arms
Uncontrolled variables
- Death rates
- Disease
- Rainfall
- Animal and human impact

14. Thank You