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for the garden
desert gardening basics
mother nature’s rhythms
Mother Nature’s Rhythms
September, 2014, Page 142
Photo by Art Holeman
How climate affects your garden
If you notice that Texas ranger shrubs burst with purple blooms during periods of high humidity, or welcome monarch butterflies refueling on your milkweeds during their fall migration to Mexico, congratulations—you are an amateur phenologist!
What Is Phenology?
Phenology is the study of natural phenomena that recur periodically, and in particular, how such events relate to climatic conditions and seasonal weather changes. Arizonans have a front-row seat to world-famous phenological events, such as the spring wildflower displays that carpet the desert. However, observant residents note that our most spectacular wildflower shows occur only in years that receive consistent fall and winter rain.
Precipitation, as well as sunlight and temperature, are major factors influencing nature’s intricately timed events calendar. Less famous than our wildflowers, toad-like Couch’s spadefoot (
) depends entirely on summer monsoons to reproduce. These amphibians remain underground most of the year. As soon as the rains begin, they dig out and hop to a puddle, working fast to mate and produce the next generation before the water dries up.
Migrating birds time their flights north to warmer climes in relation to the amount of available sunlight. At the end of summer, the cues reverse as less sunlight and cooler temperatures signal that it is time to fly south. Seasoned gardeners understand that all variables of precipitation, sunlight and temperature influence their plants’ growth.
Why It Matters
As average annual temperatures gradually increase, and precipitation levels decrease, long-standing natural cycles may be influenced. Theresa M. Crimmins, PhD, Partnerships & Outreach Coordinator, at the USA National Phenology Network Coordinating Office in Tucson, describes some examples that they are observing. “Although there is great variability, when we experience less autumn or winter rain, we tend to see earlier flowering in saguaro and later flowering in herbaceous perennials, such as Parry’s penstemon, caliche globe mallow, Indian paintbrush, and shrubs like pink fairy duster,” says Crimmins. “If we continue to experience warmer, drier fall and winter conditions, then we may begin to see impacts on the pollinators that depend on these plants being in flower at a certain time of year.”
You can help researchers study these impacts by watching what is happening with plants and creatures in your landscape or neighborhood and entering your observations into an online database. Many such opportunities exist for citizen-science participation, so seek out programs studying your favorite creatures and plants. The programs provide specifics on what to observe and how to record it. Check out these sites as a starting point:
Nature’s Notebook, USA National Phenology Network (
): Observations can be recorded on a mobile app for smart phones.
Arizona Audubon (
): Collaborating with Nature’s Notebook, they are observing pollinating bees, butterflies and hummingbirds common to Phoenix’s Rio Salado Habitat Restoration Area.
Monarch Butterfly Journey North (
): Record your first sightings of eggs, larva, adults and milkweeds.
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