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Sagebrush

12 Mar
Sagebrush.

Its aroma is almost an aphrodisiac.

It is the timeless scent of an ancient organism
that evolved with the sand and deserts
of the Great Basin.

Many of the Artemesia spp. are very aromatic; their leaves lush with terpenoids. These aromatic lipids are volatile and will relinquish their scents when leaf cells are crushed, or even under the right weather conditions.

Adding to the symphony of volatile compounds are the three isoprene rings that build the  sesquiterpenoids; lactones that repel herbivory, invite the sagebrush checkerspot butterfly to lay their eggs, and gall midges to build galls to house their nymphs.

But they also attract humans that cherish the yin and yang of their leaves and scent. The silver hairs, the trichomes, on the leaf surfaces that catch the sun and dew; the aroma they impart when crushed between fingers, the scent when scattered upon a fire.

In a harsh land where sun and sand cover the earth,

in the shadow of the mountains,
sagebrush provides shade for sage grouse,
structure for fly nymphs,
caterpillar homes,
and an aroma that
sits
and
waits
between the fingers
of the Ancient Ones.
Sagebrush,
all Artemesias,
are my spiritual plants.
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The Grandfather Rock and its children

15 Sep

Summer has been busy with family and work on the refuge. A four-day weekend was welcomed, especially by the lake. I took advantage of some down time and brought my sketch book with me, finishing a sketch started a year ago while hiking around Fish Lake on Steens Mountain in southeast Oregon.

A windy and chilly day at nearly 8,00 feet, but every day on Steens Mountain is glorious. The wind whipped the deeper water surface only the middle of the lake. The group of poplars on the opposite shore were home to a nesting pair of ospreys. Watching the immature siblings practice their hunting, kiting, and diving skills was an immense thrill. One of the adults interrupted them to demonstrate how it’s done. After the adult rose from the water with a fish, it shook the water off its feathers, flew to an aspen tree branch with its meal, and seemed to taunt the offspring by standing on its fish while glaring at them.

I sat on a bare spot of ground next to the water and sketched two pages. A section of the lake and two plants near me. I watched and listened. I finished the lake sketch just now. It’s as if I was there, right now.

I remember, and still feel the peace there.

Steens Mountain is a Grandfather Rock. It has many, many stories to tell if one is willing to listen. And many Children live on its skin: elk, hawks, mule deer, coyotes, badgers, butterflies, lichen, mosses, sagebrush, pines, aspens, and so many more. When visiting, listening, and being respectful, you will learn many stories, like sitting at the feet or in the lap of a Great Grandfather.

When I am there,
I am just a Child,
eager to learn the stories.

Sagebrush Galls: Medusa!

16 May

“How galling!! The audacity of this insect making a home in me!”

True; no matter how one organism looks at it, it’s annoying. The word ‘gall’ originates from Middle English (~ 900 A.D) and refers to bile, the bitter fluid from the gall bladder. The figurative word ‘galling’ refers to irritating, offensive, audacity and very annoying behavior.  But how did an abnormal plant growth acquire the same name, gall?

We may never know.

As a child roaming the woods and wild fields, I would often collect tree and shrub leaves and twigs that had protruding bumps in a variety of shapes.  I wondered what these odd shapes were, but it never occurred to me that they might be injurious to the plant, or even malicious at all. Nor did I know then how they were formed.

One day while wandering in the field I found a particularly large growth on the stem of a shrub. Pulling out my magic little ‘looking glass’ (pocket magnifier), I watched half a dozen little translucent bugs crawl out of the ball-shaped growth. In a short time, these bugs acquired color and their wings unfolded away from their bodies. I wondered if the abnormal-looking ball of green was a home for these bugs, and only much later did I learn they were called ‘galls’. And from then on, anytime a person uses the word ‘gall’ or ‘galling’, all I can think of are these appropriated plant cells that serve as a home for small insects.

Five decades later and I’m still fascinated by galls!

Here in the high desert of the Great Basin, galls are common on sagebrush, the most dominant plant. What surprises me is the morphological variety of these galls: the colors, shapes and sizes. So, like the child I was (and probably still am), I have been collecting samples to take back with me, as well as photographing them.

What are galls, anyway?

Galls are an abnormal plant growth induced by various parasitic organisms (1), usually insects. These latter galls will be the focus of a series of posts here as I find examples.

Galls serve as ‘incubators’ for developing insects where they gain nutrition and protection from environmental conditions and predators. Some galls are colorful and easily distinguished from the other plant material. Some are wooly, some round and colorful like tiny plums, some are lobed, and others have spiky protuberances.

Gall-inducing insects are usually species-specific and sometimes tissue-specific on the plants they parasitize. Galls can be found on leaves, stems, shoots, flowers and roots. Combined with gall morphology, these traits will often help to identify which insect is associated with them. However, identifying the insects inside will be the confirmation.

These insects manipulate and exploit the chemistry and physiology of plant tissue to their own benefit and development. Accordingly, galls act as physiological sinks for mobilized plant resources, mostly as nutrition for larvae. Fungi sometimes grow on the interior of the gall surface on which the larvae feed.

Like little houses, galls physically serve as protection from the sun, wind, rain and snow. In fact, because the gall-forming insects control gall formation so well, galls are commonly referred to as their extended phenotype. However, several predatory insects have also adapted to this system by inserting their own larvae inside galls. Then a battle for who eats whom ensues until maturation of one or both species. It’s not uncommon to have more than one species of insect emerge from a gall, but only one of those species induces galls.

Protection is one explanation for the high levels of compounds, such as phenolics and tanins, found in many galls. This is considered a defensive gall trait, protecting the gall against natural enemies outside. Thus, in addition to serving as a nutrition sink and physical protection, some galls have a natural chemical defense.

Sagebrush gall midges

Like any plant, it’s an insect-eat-leaf world out there for sagebrush. Of the 237 species of insects that are associates of sagebrush, 42 are gall-forming insects. Of those, the most predominant are Cecidomiidae, or gall midges. They are a small family of tiny flies that are associated with gall induction.

The most abundant gall midges found on sagebrush are of the Rhopalomyia genus. Although there are 32 species, not all may be present in the same location and area. A recent study suggests that land use or local abiotic conditions may greatly influence the diversity of gall midges.

The adult midges lay eggs in the sagebrush stem tissue. The eggs hatch and the larva secrete saliva into the plant. Compounds in the saliva alter the growth of the injured plant cells and the tissue produces a swelling, or gall, around the young insects. However, the size, shape and color of the developing gall are typically specific to the gall midge species. On the other hand, one species unusually induces a wide range of gall morphologies.

Medusa Galls

During a recent camping trip on Steens Mountain in SE Oregon (and bordering the Refuge), I found many specimens of Medusa galls (Rhopalomyia medusa) on Big Sagebrush (Artemesia tridentate). As seen in the photograph, these galls are composed of numerous leaf-like structures. Looking at the long miniature leafy structures, it’s easy to see how this gall was called “Medusa”.

Medusa Gall on Big sagebrush

The galls develop in October and rest during the winter. They reach full size in the following spring and adult midge flies emerge in April or May. When I was there, May 9-11, the galls were intact with no sign of emergent flies. Considering the elevation (7,300 feet) where I was hiking, patches of snow were common and the climate was barely spring-like.

Authors of a study (2) sampled arthropod diversity on sagebrush in two ecosystems, one surrounded by dryland agriculture and the other area protected from agriculture and significant human use. Their data suggests that diversity of gall midges is highly variable with the dynamics of arthropod-sagebrush interactions and the sagebrush ecosystem. Interestingly, R. medusa was one of a few species that served as an indicator species in low human impact sagebrush habitats. A good description of where I found the many specimens on Steens Mnt.

So, do these galls negatively affect the sagebrush? We will examine that question in a later post!

1. Some bacteria species can also cause galls. This was my first introduction to galls in undergraduate university. Crown gall (Rhizobium radiobacter, formerly known as Agrobacterium tumefaciens) is the textbook and lab example used in plant pathology and lab classes. It is also a common tool to teach Koch’s Postulates. Soil bacterium inserts a small segment of DNA (T-DNA) from a plasmid and into the plant cell. This DNA encodes for genes that produce a plant hormone, auxin (indole-3-acetic acid), via a special pathway that is not used in most plants. Thus the plant has no molecular means of regulating the production of the exocrine hormone. The T-DNA also signals extra production of a group of plant hormones called cytokines, which are involved in cell division. These hormones are responsible for the tumor-like growth of plant tissue and form the galls.

2. Sanford, M.P., Huntly, N.J. 2010. Seasonal patterns of arthropod diversity and abundance on Big sagebrush, Artemisia tridentata.  Western North American Naturalist, 70(1): 67-76.

Northern Great Basin, Round Two

5 Apr

Example of igneous rock from volcanic deposits of ash, later terraformed by rifting, faulting and moving water.

No matter where I go in this open country, the high desert of the northern Great Basin finds me smiling inside and out.

My first immersion in the high desert here in southeast Oregon was in 2010 when I spent two weeks living off the back of a 350cc motorcycle. It’s springy high suspension and knobby tires allowed me to travel in the backcountry. Most nights were spent in a small tent and warm sleeping bag, under a dark sky bejeweled with bright stars that couldn’t be found where I was living in Texas during that time in my life. From dust to snow and freezing rain to hot dry sunshine; from owls screeching overhead to a silence that roared in your head, it was all memorable.

I didn’t want to leave.

The transition from the Cascade mountains with giant scaly pine trees to the dry deserts was transforming. Standing on an outcrop, a memorable scene stretched below. Black volcanic seams and outcrops meandered through a gray-green carpet dominated with sagebrush. Ribbons of blue streams whose edges bristled with willows tickled that instinctive draw towards water. Occasional water-filled basins reflected the white clouds overhead, while dry playas were ground-clouds of dried white salt or lime.

Every time I come here I am reminded of similarities with my beloved Big Bend desert in southwest Texas. The high desert here shares geological and climatic features with the northern Chihuahuan desert, albeit colder in winter and less hot in summer. Topographical features here, typical of Basin and Range*, can be suddenly dramatic or gentle. Here are also the ‘big open skies’ that endear Big Bend to many people. Magnificent sunrises and sunsets are never boring here. And the clouds, from daily cotton balls to dramatic forms imparted by storms are continual award-winning players on the atmospheric stage.

Yet this is a kinder and gentler Big Bend; few thorny plants to grab and bite you, an astringent and intoxicating scent of sagebrush, and more recent volcanism. The most compelling feature for me is its presence of water. This is a land where land and water meet. It is a juxtaposition of water and dry climate and land. Consequently, the diversity and population numbers of wildlife outnumbers those found in Big Bend. Life here, and its interaction within the variety of ecosystems, is never boring. This overlap of water and land can’t be found in such intensity and variety in Big Bend.

Marshes fed by snow melt and crucial for migrant and summer nesting birds on the Pacific Flyway. MNWR.

Last summer was my introduction to Malheur National Wildlife Refuge and the surrounding area. This spring and summer will be like jumping in with both feet and getting my hands and feet dirty. Thus far, my first week has been quite rewarding. And I promise to post more about this region during months to come.

* For a primer on the geography of the northern Great Basin, see an earlier post from last summer (2014). Another post describes more local geography of the Harney Basin.

High Desert & Great Basin. Part 2

24 Aug

“Cataclysmic transformations such as moving continents, lava inundations, freezing Ice Ages, and apocalyptic floods exterminated entire plant and animal communities while successive new life forms adapted. Relative to these expansive epochs, human life spans seem but mere seconds in duration. This myopic snapshot of our current familiar environment with its modern species can foster an inaccurate perception of unchanging surroundings. But the fossil records tell us otherwise.” – Alan St. John, author of Oregon’s Dry Side.

Climate change is not a stranger to the Pacific Northwest. With two mountain ranges that run north and south, modern residents and visitors can experience the coastal fog or cool and temperate summers and winters in Oregon’s Willamette River valley between the Coastal and Cascade mountain ranges. On the east side of the higher peaks of the Cascades, and in the rainshadow of these same mountains, lies central and eastern Oregon. Here, springtime is later, summers more hot and dry, and winters cold and snowy. Yet a common denominator throughout the state is water, just in varying volumes and persistence. Water is not a stranger to even the most arid regions of modern Oregon.

Not only did Oregon’s terrain change and shift numerous times, so did the climate. Fossils from eastern and central Oregon, especially from the John Day River area, reveal the climatic conditions and the flora and fauna that lived in the area beginning 55 million years ago (mya). After a long period (~10 my) following global decimation by a planet-wide catastrophe in the Paleocene , life began to repopulate the entire continent. The Pacific Northwest became a lush subtropical region dominated by forests. Small mammals that survived in small pockets during the catastrophe began diversifying into a multitude of forms.

Conditions shifted again, possibly due to another global catastrophe,  some 34 mya to a cooler and drier temperate climate. Grasslands replaced subtropical forests and animals more suited to grazing dominated, as did their predators. This cooling trend continued on into the Pleistocene and culminated in the Ice Age.

Climate in the Pacific Northwest shifted again 10-12 thousand years ago back to more temperate conditions. The ecosystems we see now are the results of this shift. This long and active changing geological and climatic history has left its marks on the land and the life that lives on it.

Harney Lake in early August.

Northern Great Basin

The Great Basin’s northern region lies in Southeastern Oregon between the dramatic upthrusts of fault blocks and in sunken basins. Surrounded by miles of dry steppe vegetation zones are many ancient inland seas and lakes. What was once teeming with wading animals, lush tropical trees,and ancient birds are now sun-scorched basins. These dessicated lakebeds with alkaline and sandy soils are the only true deserts of Oregon.

Because the term ‘desert’ is a wide classification of regions that have an annual moisture deficit, such areas can be further categorized as semi-arid or arid. A semi-arid region is a climatic area that receives precipitation less than the combined potential of evapo-transpiration (combination of transpiration via plants and evaporation*), although not extremely. An arid region has a severe lack of available water and where the evapo-transpiration rate significantly exceeds annual precipitation to the extent that normal growth and function of all life is impaired or limited.

Although most of central and eastern Oregon is considered semi-arid, a ‘true’ desert is an area where vegetation is exceedingly sparse and rainfall is also very rare and infrequent. Interspersed amongst the semi-arid steppe lands of the northern Great Basin are isolated lakebeds (playas) that lie within double rainshadows. Precipitation is usually less frequent due to the barriers of the Cascade mountains to the west and tall block fault mountains to the east. Some of these playas may be simply expanses of sand or cracked alkali-encrusted soil, or they may hold seasonal water.

Thriving Watersheds

As the climate warmed, melting glaciers of the Ice Age formed giant pluvial lakes covering much of the Great Basin while rivers carved deep canyons and gorges. Temporary connections between rivers and the lakes may have permitted fish to migrate from the rivers. But, as the climate warmed, the inland lakes dwindled or dried completely. Many of these reservoirs became shallow lakes with feeder streams and fish populations were trapped, where some evolved into unique species.

Most of these basins are closed systems that retain water with no outlfow to external bodies of water. Instead, precipitation draining from higher ranges seasonally feed marshes and playas where they may be seasonally or permanently wet depending on annual evaporation and the presence of springs.

Seasonal and annual water levels depend on a variety  of factors: winter snow pack, rate of snow melt, cycles of drought and rains, and summer temperatures. Typically, water in drainage basins either flows out into larger water bodies or diffuses through permeable rock. However, water in many of the playas in the Great Basin leaves only by evaporation and seepage. Thus the bottom of such basins become salt lakes or salt pan.

Buena Vista marshlands of Malheur National Wildlife Refuge.

Harney Basin: High Desert and Wetlands

At the most northeast corner of the Great Basin region and in Oregon is Harney Basin. Covering 1,490 square miles, it is the watershed of Malheur and Harney Lakes. Both are not true lakes, but playas once divided by a sand dune. Before the sand dune was breached by settlers in the early 1900’s, the Malheur Lake was a freshwater lake, while Harney Lake was saline-alkaline.

The basin receives an average of 6 inches of rain per year, but the surrounding mountains may have 15 inches of precipitation. Both playas receive water from streams originating within the basin in the surrounding mountains, including the Silvies River from the north and the Donner und Blitzen River (often called the Blitzen River) from the south. The watershed of the latter river is the Steens Mountain, which stretches some 50 miles north to south and attains an elevation of 9,733 feet at the summit.

The Harney Basin is considered a part of the larger High Desert Wetlands ecoregion, which consists of high desert lakes and surrounding wetlands. These marshes and seasonal reservoirs provide critical habitat for nesting and migratory birds as well as associated upland birds and mammals. Both Harney and Malheur lakes cycle between open water in wetter years and marshes in drier years. The wetlands around Malheur Lake and the Blitzen River form a wetlands oasis in the basin and has served as habitat for many migratory bird species since before human presence in the Basin.

Malheur Lake and most of the Blitzen River valley are now included in and managed by Malheur National Wildlife Refuge. Each year as many as 320 species of birds and 58 species of mammals can be found in the refuge. Among these, Malheur serves as a Pacific Flyway stop for the Northern Pintail duck and Tundra Swan, Lesser and Greater Sandhill Crane, Snow Goose and Ross’ Goose. Ducks, grebes, pelicans, terns, and trumpeter swans are drawn to the numerous ponds, marshes and lakes. Many raptors, including Peregrine falcons, also call the Refuge home.

This juxtaposition of high desert and watershed with its rich wildlife is indeed a jewel and gem. And one I am grateful to experience this summer.

“Unaccustomed to the desert, we may literally overlook what is directly in front of us. A true irony: not being able to see the desert for lack of trees.” – Alan St. John, author of Oregon’s Dry Side.

 

* Potential evapo-transpiration is the amount of water that would be evaporated and transpired if there was sufficient water available.

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