Dead heat and June Gloom: connecting California’s disparate summer climates

It’s July. Areas of the northern hemisphere that receive summertime rain are experiencing the height of the growing season, and ecologists, conservationists, and land managers make their summertime hay by vigorously pursuing field activities while plants and critters are at their most active. Mosquitos thrive, fish jump, and prairie grasses grow taller by the minute. But summer is not the prime growing season everywhere in the world.

In southern California grasslands, which enjoy a Mediterranean climate, the growing season ended months ago for most annual plants. The prime time for ecologists to botanize has past; our hills are now a lustrous gold, spring’s crop of annual grasses and forbs long since senesced. The summer dormancy observed in California’s grasslands can also be observed in its deserts. Holding the record for the hottest place on Earth at 134° F, Death Valley’s summers are definitely not the region’s “growing season” (except if you are talking about the growth of heat-seeking tourists, perhaps).

As the desert heats up in the summertime, something interesting happens. Warm air rises and creates pockets of low pressure, drawing air from the coastal areas to the west. A strong high pressure system over the ocean can allow moist, cool marine air to drift onshore, and before you know it the coast is socked in: foggy days, fleeting glimpses of late afternoon sun, and infuriating flight delays are legendary summer realities along the California coast. Who hasn’t heard the quip (erroneously attributed to Mark Twain), “the coldest winter I ever spent was a summer in San Francisco”?  This condition is called June Gloom, despite the fact that coastal areas can be overcast, misty, or downright foggy much of late spring and early summer, not just in June alone. So, while the desert experiences temperatures in the 120’s, the coast can be a damp and chilly 65° F.

Whole ecosystems have evolved to cope with these disparate summer climates. Along the foggy coast, 20-40% of the total water used by redwoods comes from fog input (as opposed to rain), and for other maritime chaparral plants and some lichens, fog is the primary source of water in the dry season. Also, people in other arid yet foggy areas have developed ingenious ways of capturing the moisture from the air to use as drinking and irrigation water. Outside of the fog belt, summer dormancy and other strategies of heat and drought avoidance allow plants to survive the hot, dry conditions that characterize California’s inland areas and deserts.

Despite the mercury-bursting temperatures, this is the time of year that I choose to visit a site less than 25 miles from the hottest place on Earth. I go to monitor several properties along the Amargosa River, which flows through the Mojave Desert to terminate in Death Valley when enough rain occurs in the winter. When I visit, the river is a clear, narrow stream rather than a raging, flood-swollen torrent. The summer gives me a chance to appreciate the river as a true riparian oasis—an area providing habitat for fish, plants, and hundreds of bird species. The site seems unreal, surrounded by a vast desert shimmering in triple-digit heat. It is not the heat itself, but the miracle of respite from the heat, that draws me to this place each summer.

And if I get too hot, I can always drive to the beach.

Gone to the dogs: conservation’s star canines

My introduction to working with dogs came fifteen years ago, on the tall grass prairie of Kansas. With the assistance of two very willing Australian Shepherds and one more restrained Samoyed, the dogs’ owner and I designed and carried out an experiment to test how far canines could smell, and how their prodigious noses might be affected by changes in environmental conditions such as air temperature, wind speed, and relative humidity.

As it turned out, the dogs were able to pick up and alert us smell-challenged humans to the scent of a standard odor attractant pill up to 1 kilometer away if the winds were gentle, temperatures mild, and the relative humidity was high. While this finding alone was amazing (I could only smell the stinky pill if it was within an arm’s length of my nose), what our study implied was even more interesting.

You see, we were using the dogs as models for their wild cousins – Canis latrans, the coyote, to better understand the population dynamics of coyotes on the prairie, and large predator ecology of the region more generally. To study coyote population sizes at the time, wildlife ecologists typically set out an odor attractant, surrounded it with spread-out sand, and then came back later to record coyote tracks in the sand. But this method didn’t provide a good estimate for how large of an area is sampled. The question remained: from how far away could coyotes smell the odor of the attractant pill? Because coyotes are wild animals, designing a method to allow us to judge their ability to smell would have been difficult. Domesticated and agility trained dogs (with otherwise normal smelling capabilities for dogs) provide a rough approximation of what coyotes might be observing, thereby opening a window between humans and the wild, and giving us some insight into the coyote’s sensory world.

Photo by Ted Van Pelt. Used under a Flickr Creative Commons License.

The ability of dogs to smell better than humans is legendary, and their ability to be trained to alert humans when they pick up a particular scent has allowed people to harness their sensory capability for a variety of purposes. In The Sign of Four, Sherlock Holmes prefers the help of a dog named Toby to “that of the whole detective force in London”. Dogs have also been trained to sniff out leaky gas lines underground, explosives, narcotics in the luggage of drug traffickers, even the onset of a seizure or cancer cells in the human body. The use of dogs in conservation is more recent, but no less potent. Examples include the ability to detect the unique scent of rare plants or the traces of small animals (such as salamanders) that are difficult for people to find easily.

While the methods used by predator ecologists to track larger animals have changed significantly in the past two decades due to advances in radio and GPS technologies, for a visually-focused species such as humans, dogs are still a huge boon. Until we all have Star-Trek tricorders that can mimic a dog’s capabilities, Man’s Best Friend is also our best bet for tracking scents. Kept on leash and properly trained, dogs can be one of conservation’s best friends, too.

Keeping their cool: desert plants have a lot to teach us about climate change adaptation

Climate change isn’t new. The earth’s organisms have faced the “cope, adapt, or die” paradigm presented by changing climatic conditions since the inception of life on earth more than 3 billion years ago. Some species already live in extreme conditions (a topic demonstrated in the last blog post) – at the earth’s freezing poles in the dead of winter, at the apex of tropical mountain peaks that receive tens of meters of rainfall a year, and deep in the dry deserts that comprise a third of  the earth’s land area.

The plants and animals able to survive these extreme conditions may have something to teach us humans about climate change adaptation—especially when the organisms are incapable of crawling up to a cooler elevation or slithering into a deeper riverine pool to escape a heat wave. As a general rule, plants spend their lives rooted to a single spot on the earth. So they need to be able to withstand 365 days per year of whatever nature can dish out in terms of weather. Plants from hot deserts—such as the prickly cholla cactus—are no exception, and they have evolved a broad range of impressive strategies for coping with the hottest, driest climate in North America, where a years’ worth of rainfall may come in a single extreme event.

Optuntia sp. blooming in the Mojave Desert (copyright Sophie Parker 2008)

These desert denizens provide us with valuable insight into biological and physical adaptations that allow for survival on a hotter, drier planet that is subject to extreme events (as climate change experts are currently forecasting). In addition, deserts plants hold fascinating keys to longevity: the California deserts are home to both the world’s oldest tree—a Great Basin bristlecone pine (Pinus longaeva) between 5,062 and 5,063 years old—and “King Clone”, the oldest clonal colony of creosote bush (Larrea tridentata), which is estimated to be 11,700 years of age. From the perspective of climate change and adaptation, the ancient creosote clone is particularly intriguing, as the climate under which it originally germinated (at the tail end of the last ice age) was different from that in which it lives today.

What strategies allow desert plants to survive harsh conditions? Well, plants protect themselves from intense heat by producing smaller leaves (spines in cactus), by using water-saving methods of photosynthesis (such as Crassulacean acid metabolism), by growing protective hairs to deflect sunlight, or by producing thin leaves that cool down easily in a breeze or waxy leaves that prevent water loss. They can also capture moisture by having short roots that expand when it rains, or extremely long, fast-growing roots that can quickly tap into groundwater. Cacti contain flexible structures that allow their stems to expand and store extra water to use when it isn’t raining. Finally, plants have evolved the ability to delay germination and growth to coincide with water availability and mild temperatures, thereby avoiding the exposure of tender young seedlings to the harshest conditions.

You may be thinking at this point: these adaptations are great, but why should I care? Beyond their intrinsic beauty and their support of other desert species, plants have tangible benefits to offer society. Using biomimicry, scientists and engineers have begun to copy the strategies of animals and plants in nature in order to solve human problems. Desert plants may serve as particularly helpful guides as we attempt to adapt to a hotter and drier planet. We’ll have the best chance to learn from them if we protect the habitats where they are found.

Biodiversity Where You Least Expect It

Try this: close your eyes and conjure up an image of a “biodiverse ecosystem”.

What do you see? Perhaps a tropical rainforest, dewy vines glistening, howler monkeys calling through the trees, and butterflies flitting in the sun-dappled heat? Or maybe you pictured a coral reef, replete with white-tipped reef sharks, sea turtles, brain coral, and giant iridescent clams? Admittedly, tropical ecosystems in places such as Costa Rica and  Indonesia do contain a stunning array of macro-biodiversity– that is, larger plants and animals.

But what about the little guys? Microbes make up the vast majority of life on earth, and they are ubiquitous; a single teaspoon of your backyard soil may harbor millions of individual organisms and upwards of 100,000 unique microbial taxa. Bacteria are found in nearly every environment on earth, from the hottest hydrothermal vents at the bottom of the ocean to the coldest, iciest mountain peaks in the Andes. In fact, the search for “extremophile” microbes in some of the most physically and geochemically remote and harsh environments on earth has led to some fascinating discoveries, demonstrating that some microbial species can thrive under conditions that would quickly crush, desiccate, freeze, starve or asphyxiate most living things.

Because humans are relatively large organisms, it is easy for us to overlook the microscopic world. But here’s the irony: microbes make up a good deal of us! That’s right; 90% of cells in the human body are not human…they’re actually microbial! Our large body size and varied physical tissues provide microbes with a diversity of niches within and upon our bodies, and our microbial companions have adapted to live in them (see Figure 1). We’ve all heard of “germs” on the surface of our skin, and are familiar with the idea of bacterial, viral, and amoebic pathogens in the gut and elsewhere, but the flora and fauna of the human body is so much more interesting than these well-known examples… biologists are beginning to map and understand the human microbiome, and how our unique microbial flora can impact our health, and even our behavior.

Figure 1. Not just a human after all.

(photo credit: Valentin Loschinin under flicker creative commons)

You may be wondering at this point: why should I care about microbial biodiversity? Won’t it always be there? Well, unfortunately, the answer is not necessarily. Microbial biodiversity can be lost (both on humans and within the larger world) just as macro-biodiversity is lost, and this loss can have major impacts on human well-being and ecosystem health. One of the key lessons of conservation is that we are not separate from the ecology of life on Earth; we coexist in concert with it. Nothing brings this point home quite like the knowledge of an intricate, interconnected human body ecosystem: the biodiversity hotspot of you.