We do not inherit the
earth from our ancestors,
we borrow it from
our children.
- Native American Wisdom

Monitoring Saguaros at the Park

Saguaro National Park was established to protect one of the nation's most unique habitats -- a relatively unspoiled portion of the Sonoran Desert, and arguably, one of the densest saguaro forests in the world.  To fulfill its mission of protecting its namesake plant, the park undertakes regular efforts to monitor the health and status of these giant cacti, and to try to better understand the complex ecological interrelationships that govern the health and character of saguaro stands.  Extrapolation from saguaro census data taken in 2020 estimates that there are approximately 2,066,281 saguaro cacti at Saguaro National Park- 460,478 at the Rincon Mountain District and 1,605,803 at the Tucson Mountain District. This is an increase of over 100,000 from the 2010 Saguaro Census results.

Interpreting the results is complicated because the saguaro population changes slowly. Saguaros are slow-growing plants that can live more than 150 years but, conditions need to be perfect for new saguaros to germinate. The real value of the 10-year Census is the insight it provides about long-term changes over many decades-- some plots have been monitored since the 1940s. The major findings from the 2020 Census are -- 1) The park's saguaro population is large, growing and healthy. A surge of young saguaros that germinated in the late 1960s through the mid 1990s are thriving. They are growing under "nurse trees" and are not yet visible on the landscape; 2) Fewer young saguaros survived and entered the population in the mid-1990s. This slow-down was caused by the lack of ideal conditions for germination and continued through the mid-2000s; 3) More very small saguaros (less than 15 years old) were found. The 1-2 inch saguaros were found in foothill and rocky areas of both districts; 4) Saguaros are impacted by the effects of climate change. Saguaros germinate and grow faster during cooler and wetter periods. High temperatures and drought do not allow for germination and cause saguaros to grow more slowly and bloom earlier in the spring; 5) Increased protection of saguaros and efforts to control invasive buffelgrass are working. Since the 1990s saguaros have received greater protection and removal of invasive plants have allowed more saguaros to grow and germinate. 

Through the Adopt a Saguaro funds, Friends of Saguaro was able to support the 2020 Saguaro Census. The large, high-profile study is conducted every ten years and provides a count of how many saguaros are in park while collecting vital information on their long-term health and vitality. Click here to learn more about the census.

You can support the park's saguaro monitoring efforts by donating to the Friends of Saguaro Adopt a Saguaro program.  All proceeds are dedicated to provide a reliable revenue stream for continued saguaro research and protection activities -- as we attempt to ensure the conservation of the iconic symbol of the American southwest.