Southwest Season Tracker campaign

Greetings! Your reports of leafing, flowering, and fruiting of southwest shrubs continue to roll in! Your observations will be used to verify predicted dates of the start and end of the growing season based on an ongoing study of plant phenology at the Jornada Experimental Range . At the Jornada, researchers are seeing ripe fruits on honey mesquite. Read on to find out what your fellow observers are reporting for evergreen and drought-deciduous shrubs across the Southwest.

Honey Mesquite ( Prosopis glandulosa ) ripe fruits, Photo: Ruben Baca

What you are reporting so far this year

Observers have reported on southwest shrubs at 47 sites so far this year, up from 42 sites at the time of our last message. Is your site on the map?

Sites reporting on southwest shrubs in 2019. Colors correspond to species names across the top; darker colors indicate more observations made for that site. Green outlines indicate more than one species observed.

We have 17 Local Phenology Programs (LPPs) submitting data on southwest shrubs this year. The LPPs submitting the most data so far this year continue to be Joshua Tree National Park in CA , PHENOMET Bajada in NM , and McDowell Sonoran Conservancy Phenology Trails in Scottsdale, AZ . We also have 20 individual observers who are submitting data. Thank you for your efforts!

Summer means fruiting time for many species of southwest plants. Some of our Southwest Season Trackers species, such as honey mesquite and creosote bush, have multiple periods of fruiting or fruit at different times in different parts of the Southwest. Other species, such as soaptree yucca, fruit only during certain times of the year. The phenology calendar below shows when observers across the Southwest reported a "yes" for the life cycle stage for that species (represented by the colored bars) or a "no" (represented by the gray bars).

Taking a closer look at your observations of honey mesquite fruiting in New Mexico, we can see that you reported fruits starting in May, and ripe fruits starting in June. The peak in number of plants with ripe fruits started in August.

If we compare your reports of honey mesquite fruiting in New Mexico to reports in California, we can see fruiting started about a month earlier in California, while you reported ripe fruits at approximately the same time.

Your reports of creosote bush from Arizona show a high proportion of creosote bush with fruits since the beginning of year, and a peak in ripe fruits at the end of June.

You reported fruits on soaptree yucca in Arizona starting in mid-May, with a peak in July. Last year, you reported fruits in June, with a peak in October.

A question to ponder... Why do you think soaptree yuccas have a limited flowering and fruiting window, while other species like creosote bush and honey mesquite have more flexible flowering and fruiting times? We'll answer that in our next message!

Earn your Southwest Season Tracker badge! You can earn this badge by observing a Southwest Season Tracker species once a week for six separate weeks in the same year. See it on your Observation Deck . Thank you for your contributions to this important project!

Contact Erin Posthumus erin@usanpn.org 520-621-1670 bio

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