RELATIONSHIP BETWEEN TOPOGRAPHY, VEGETATION, AND SOILS INNORTHEASTERN CALIFORNIA

R. Earl Storie 1

Introduction

During the progress of the Soil Sur-vey of the Alturas Area, Modoc County, Cali-fornia, in 1931 (l), certain types of nativevegetation were noted to have a more or lessdefinite soil or land type correlation. Thekind and distribution of the native vegeta-tion was noted to depend to a considerable ex-tent on soil differences such as drainage,salinity, lime content, etc. The correlationof native vegetation with soil salinity isparticularly valuable information to have asan aid in soil conservation and land utiliza-tion work, as well as of interest to ecolo-gists, foresters, geographers, and otherscientists. Considerable work has been doneby members of the Bureau of Plant Industry onthe indicator significance of natural vegeta-tion. Kearney (2) in Utah, and Shantz (4) inthe southwestern desert region, in particular,have pointed out the relationships existingbetween the type of natural vegetation andtopography, soil texture, soil moisture con-tent and the salinity or alkalinity of soils.Russell (3) outlined and defined severaltypes of land surface in Surprise Valley andpointed out certain relationships existingbetween the different land forms and thedrainage and vegetational covers. Since thecompletion of detailed soil studies in thisregion we are able to go still further inthis type of study and bring in the soil re-lationship.

The profile presented here shows atypical cross section of the northeasternpart of California from a point near theModoc-Siskiyou county line across the Devil'sGardens; the Pit River drainage; the WarnerMountains; the Surprise Valley; -and into thenorthwestern part of Nevada (Figure l). Thepart east of the Warner Mountains representsconditions characteristic of the northwesternGreat Basin, while the territory to the westis typical of the northwest intermountainlava region. Being a grazing area a largepart of the natural vegetation remains undis-turbed, therefore soil-vegetation figures are

significant. In addition this cross sectionis representative of conditions existing else-where in southeastern Oregon and northwesternNevada. The total distance represented bythis profile is about eighty miles.

Climate

The climate of this region is charac-terized by cool wet winters and warm dry sum-mers. The valleys and lower plateau have asemi-arid type of climate with the average an-nual rainfall ranging from about ten to nine-teen inches, while the mountains have a high-er rainfall and considerable snow. From theeastern crest of the Warner Mountains therainfall drops off very rapidly, probablyfrom a maximum of about forty inches to aslow as six or eight inches on the Nevada des-ert, all within a distance of about eightmiles. The native vegetation reflects thisdifference as one progresses from the dark-brown pine and fir-covered soils in the Warn-er Mountains down to the light-colored cal-careous greasewood-covered soils of the Nevadadesert. Russell (3) classes the climate asa borderline between the cold Steppe and theWinter rainfall type of microthermal climate.

Physiography and Relief/

As indicated on the profile (Figure 2)this region has an elevation of about 4,000to 7,000 feet above sea level. The lavaplateau (Land Type F2) has an elevation ofabout 5,000 feet, the Pit River Valley an ele-vation of about 4,500 to 4,600 feet, theWarner Mountains paralleling the Nevada lineoccur at an elevation of 5,000 to 7,000 feetand Surprise Valley located east of the Warn-er Mountains has an elevation between 4,500and 4,900 feet. Pit River rises in the Warn-er Mountains and cuts through the lava pla-teau of northeastern California flowing westinto the Sacramento River. As indicated onthe sketch map there are a number of dry lake

University of California, Berkeley, California.

567

568 SOIL SCIENCE SOCIETY PROCEEDINGS 1937

OREGON

Figure 1. Sketch map of northeastern California showing location of profile.

beds which may fill with water in wet years.During dry years they are usually dry. Carry-ing a high content of alkali there is no veg-etation. The largest of these is Goose Lakewhich is located on the line between Cali-fornia and Nevada.

In the land cla-ssification used inthis paper A is used to indicate valley oralluvial fan land; B designates basin orbasin-like land; C_ designates low terraceland; I) indicates higher terrace land; E des-ignates upland that may be considered agri-cultural; and F designates the steeper orshallow upland areas that are non-arable.These broader divisions are set up on the ba-sis of land form or topographic distinctions.Various land subtypes are indicated as Ax , A2,A3, etc. These are set up on the basis pri-marily of soil differences.

The following discussion sets forththe relationship existing between the topogra-phy, the soils and the native vegetation inthis region.

Valley or Alluvial Lands; (A)

The brown alluvial fan soils (Ax) arewell drained and alkali free. Surprise grav-elly sandy loam,, fine sandy loam, loam andclay loam are the dominating soil types. They

originally carried a sage cover but becauseof their high agricultural value have beencleared and are practically all cropped atthe present time. A considerable acreage ofalfalfa is grown on this type of land.

The dark-colored alluvial fan orflood plain soils (A2 and A3) occur on theflood plains along the Pit and other streamsof the region or at the lower edge of thealluvial fans where there is considerableseepage from higher land. These areas aregrasslands, being used as meadows-with irri-gation throughout the summer. Grasses con-sist largely of blue joint, Nevada bluegrassand other water-loving grasses. The soilsare of high organic content and .have a rela-tively high water table. The soil types arePit loam, mucky loam, clay loam and clay.These soils are usually free of harmful ac-cumulations of alkali.

Land Type A4 consists of a rim ofyoung alluvial soils lying a few feet abovethe river flood plain. The native vegetationis saltgrass and rabbit bush. These soilscan be classed as belonging to the solonchakor saline group. They present distinct prob-lems from the standpoint of use. In thisregion their best use appears to be utilizingthe present vegetation for pasture. Severaldifferent soil types fall in this group withthose of gray color predominating.

RELATIONSHIP BETWEEN TOPOGRAPHY, VEGETATION, AND SOILS 569

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Light-colored recent or young al-luvial soils (As) occupy the alluvial fansbordering the eastern edge of Surprise Valleyin Nevada. These soils are usually of fairlyhigh lime content. Occurring in an area oflow rainfall (five to eight inches) there isvery little vegetation except scattered des-ert sage. They have very little value evenfor grazing. If water was available for ir-rigation these soils would probably be ofvalue for alfalfa and other crops adapted tothese climatic conditions.

Basin or Basin-Like Land: (B)

Types B! and B2 have light-colored al-kali soils. The soils in type B, are saline(solonchak) and are barren or support agreasewood (Sarcobatus vermiculatus) , orbushy samphire (Allenrolfea occidentalis) cov-er. Lahontan fine sandy loam and Canby siltyclay loam soil types fall in this classifica-tion. Type BU occasionally has a littlegrazing value from the saltgrass but is prac-tically worthless for any agricultural usedue to the deflocculated nature of the soilsand the high alkali content.

The alkali lake beds are classed underB3. The soils are of gray or light-gray col-or, high in alkali and barren of any vegeta-tion.

Terrace or Lower Bench Land: (C)

Smooth terraces border the Pit RiverValley, Big Valley. and other valleys in thisregion which have dull brown, well-drainedsoils of semi-mature age with heavy subsoilsresting on a consolidated hard pan-like sub-stratum. The dominant vegetation is aagewith some short grasses. Due to its favora-ble topography some of this type of land hasbeen brought under cultivation but because ofits shallowness and low water-holding capaci-ty the results have not been very promising.The best use of this type of land appears tobe pasture.

Medium textured soils of the Bieber,Antelope and 'Gould series are indicated as Cifwhile the higher stonier types are indicatedas C2. Surface and subsoils are of neutralor slightly acid reaction.

Higher Terrace or Bench Land: (D)

A series of old lake delta benchesoccur at an elevation of about 5,000 feet

570 SOIL SCIENCE SOCIETY PROCEEDINGS 1937

above sea level. These bordered old prehis-toric Lake Lahontan and now occupy a positionabout 300 to 400 feet above the level of thealkali lakes in Surprise Valley. Similar oldLake Lahontan terraces occur further south inCalifornia and Nevada along the eastern footslopes of the Sierra Nevada. The soils onthese terraces are of brown or dark-browncolor, of semi-mature age and well drained.They support a native cover of sage and somegrass and are utilized chiefly for grazing.If irrigated this type of land would be adap-ted to a fairly wide range of crops.

Upland; (E)

Nearly all the upland soils of thisregion are developed on basic igneous bed-rock. Land Type E± consists of .the smootherareas, made up of brown, dark-brown or red-dish-brown soils, .neutral to slightly acidin reaction, and usually classed with theGleason loam or clay loam. This type wasoriginally covered with pine and fir timber.These soils are utilized to some extent fordry-land farming. Yields have not been highdue to low rainfall. There has been someovergrazing and erosion on this type of land,therefore it presents some conservation prob-lems. Type E2 consists of upland soils thatare stony and occupy steeper topography.These soils also have a pine or fir cover.Being steeper they are less apt to be tilledalthough much of the timber has been cut.

Non-Arable Upland: (F)

In this category are classed steep orshallow upland soils. Under FI (Rough moun-tainous land) are the steeper phases of theGleason, Aiken or Lassen series. This is typ-ical timberland. Good stands of yellow pineand fir occur on this type of land.

A lava plateau covers considerablearea in this region (Land Type Fg ). This hasa juniper and sage cover with some shortgrasses. Soils are classed as Lassen stonyclay. These soils are of dark chocolate-brown color, of neutral reaction, but have acalcareous reaction overlying the lava bed-rock. The surface is generally smooth. Thistype of land is used for graz-ing purposessince it carries some grass cover.

Summary

The following indicator significance

of natural vegetation is exhibited in north-eastern California where a cross section ofabout eighty miles in length gives condi-tions characteristic of both the northwesternGreat Basin and the northwest intermountainlava regions.

The brown well-drained alluvial fansoils originally had a cover of sage. Theyare nearly all farmed at the present time.The darker colored flood plain soils have anexcellent cover of water-loving grasseswhich are irrigated throughout the summer andconstitute excellent pasture and hay land.The moister valley soils have a rim of salinesoils which have a native cover of saltgrassor rabbit bush.

Alkali land in the basins have light-colored soils which carry a cover of alkali-indicating plants. Alkali lake beds arebarren of vegetation.

The lower terrace land has predomi-nately dark brown well-drained soils havingdense subsoils upon which the dominant vege-tation is sage.

The old lake delta benches have darkbrown well-drained soils with a giant sagecover.

The rolling upland has brown to red-dish-brown well-drained soils on which thenative cover is pine or fir timber.

The lava plateau has a juniper andsage cover.