Death Valley National Park is a remarkable place. The park is just east of the Sierra Nevada mountain range, placing it within a severe rain shadow. Rain shadows are areas of extreme aridity caused by winds from the Pacific Ocean moving eastward across the landscape. These oceanic winds contain large amounts of moisture, but are forced to drop this moisture in the form of rain or snow as they climb the western side of the mountains. This is why the western slopes of the Sierra Nevadas are lushly forested.
Once these oceanic winds reach the eastern side of the mountains, they have lost nearly all of the moisture they received from the ocean. As they descend the eastern slopes of the Sierras, these winds now pull moisture from the atmosphere. The rain shadow effect intensifies as elevation continues to drop, with dry eastern forests giving way to desert scrub and badlands.
Death Valley's Badwater Basin sits at 282 feet below sea level, the lowest elevation in North America. Remarkably, less than 150 miles away sits Mount Whitney, the king of the Sierras; at 14,494 feet, it is the tallest mountain in the contiguous United States. This incredible elevational shift gives Death Valley one of the most dramatic rain shadows anywhere in the world. On average, the region receives less than 2 inches of annual rain. This sparse rain comes primarily in the winter, leaving the region bone dry for the majority of the year.
It's tempting to think that such extreme conditions would severely limit Death Valley's biodiversity, but this profound water scarcity has been met with remarkable adaptations by native flora and fauna. In fact, despite their reputation as inhospitable and "empty" lands, California's deserts boast 420 species of birds, 96 mammals, 63 reptiles, 16 amphibians, and over 1800 plant species. You could spend your life hiking nothing but deserts and still not experience the complete diversity of life contained within them.
I visited Death Valley in April 2016 in hopes of encountering some of this diversity. I was on my way down to San Diego to visit my sister, who was due to have her baby any day. I entered Death Valley from the Nevada side. From there, I crossed over Daylight Pass in California and cut westward across the park as the highway took me upwards of 4,000 feet and at times below sea level.
I took this detour through Death Valley because the region was experiencing a rare phenomenon. At roughly 10-year intervals, Death Valley is inundated with winter rains tied to the El Niño weather event. That year, Death Valley experienced 3 inches of rain in one 5-hour period. The rains were so intense that I had to change my route through the park; the road near Badwater Basin had been destroyed by the rain!
Rain events like this do more than pummel parched asphalt; they awaken dormant seeds. You see, sometimes an area is only habitable for a few months every decade. That doesn’t mean the area can't be habitat, as long as the organisms living there can somehow avoid the extreme conditions. In the case of Death Valley’s diverse community of wildflowers, many only get to see the light of day after these intense rains. Seeds lying dormant for years finally germinate (begin to sprout) when rain penetrates deep enough into the hard desert soils. The processes stimulated by the rain are continued by rising temperatures and increasing daylight, so that by springtime, long-buried seeds finally have their day in the sun. By the time I arrived in April 2016, I had already missed a great deal of that year's superbloom. That spring, an explosion of life colored the typically barren landscapes as wildflowers blanketed the ground. By the start of the summer, every flower would succumb to the punishing heat, winds and aridity.
This brief window of life-giving time is critical for these wildflowers. Intense competition ensues as the vast arrays of flowers attract numerous pollinators. Successfully pollinated flowers are able to produce an abundance of seeds which, like their parents, will likely remain dormant until the next significant rain event. While there are always a sparse number of wildflowers that bloom in Death Valley every spring, most seeds do not germinate until spring conditions are absolutely perfect.
By the time I had arrived in Death Valley in April, most of the low-elevation wildflowers had already reseeded the soil and perished. The flowers you see here are from high-elevation areas in the park, where temperatures were a tad more forgiving.
I left Death Valley determined to return for the next superbloom. I hope to be better prepared so I can experience the splendor of the low-elevation wildflowers. As it happens, baby Nathan was born just before I entered the park that day. If he enjoys nature like his uncle, I hope to take him with me when I try this trip again.
Stay tuned for my next post, where we'll look more at the importance of seasonal timing, or phenology, in Death Valley.
Barbour, Michael; Pavlik, Brucel Drysdale, Frank; and Lindstrom, Susan. 1993. California’s Changing Landscapes: Diversity and Conservation of California Vegetation. A publication of the California Native Plant Society. Pages 7-10.
National Park Service. Death Valley National Park. 2016. Best Wildflower Bloom in a Decade. https://www.nps.gov/deva/learn/news/wildlowers-2016.htm
National Park Service. Death Valley National Park. 2016. Wildflowers. https://www.nps.gov/deva/learn/nature/wildflowers.htm#weatherandblooming
University of California, Merced. Yosemite and Sequoia Field Stations. 2019. Climate of the Sierra Nevada. http://snrs.ucmerced.edu/natural-history/climate
Jacob Ewald. April 2nd, 2016. Death Valley National Park.