PLEASE DO NOT RETIE

FROM FILES

PNW-103 April 1969

INFLUENCE OF SITK4 ALDER ON SOIL FORMATION ANDMICROBIOLOGICAL SUCCESSION ON A LANDSLIDE

OF ALPINE ORIGIN AT MOUNT RAINIER

by

W. B. Bollen, Principal Soil MicrobiologistK. C. Lu, Microbiologist

J. M. Trappe, Principal Mycologistand

R. F. Tarrant, Principal Soil Scientist

ABSTRACT

A Sitka alder seedling, growing on 5-year-old avalanchedebris below Mount Rainier, led to increased soil carbon andnitrogen and increased microbial populations over a 3-yearperiod. Over 5 years, avalanche debris decreased in pH frommoderately alkaline to slightly acid, and the "soil" surfacehad become somewhat more consolidated.

The debris and rock, deposited below Emmons Glacier by the 1963avalanche from Little Tahoma Peak, was first sampled in October 1965for chemical and microbial analysis. 1" The samples were extremely lowin available nutrients and numbers of micro-organisms as compared withsamples from under a clump of Sitka alder (Alnus sinuata (Reg.) Rybd.)on an adjacent terminal moraine disgorged by the glacier in 1897.Although only meager amounts of carbon and nitrogen were present inthe top 8 inches of the 2-year-old avalanche material, correspondingvalues for the moraine soil indicated appreciable organic matter fromthe Sitka alder and its associated mosses and lichens.

1! Bolin, W. B., Lu, K. C., Trappe, J. M., Tarrant, R. F., andFranklin, J. F. Primary microbiological succession on a landslide ofalpine origin at Mount Rainier. Pacific Northwest Forest & Range Exp.

Sta. U.S.D.A. Forest Serv. Res. Note PNW-50, 7 pp., illus, 1967.

We intend to follow development of soil and microbiological suc-cession on the Little Tahoma deposit. To plan timing of the next majorsampling, we collected interim soil samples in September 1968, nearly5 years after original deposit (fig. 1). Methods were the same as in1965 and sampling sites were comparable, though fewer. In addition,three subsamples, later composited, were taken from immediately aroundthe roots of a 3-year-old Sitka alder that had become established sincethe 1965 sampling on the new "soil" about 10 meters southwest of theadjacent terminal moraine. This alder had a nodule cluster 3 centi-meters in diameter at its root collar. Soil samples were collected,prepared, and analyzed by the methods previously described.±I

Results show a striking increase of total carbon, nitrogen (ob-tained by the Kjeldahl method), ammonium, and, to a minor degree,nitrate under the young alder (table 1). Molds, mostly Penicillium sp.,.were much more numerous near the seedling roots, and numbers of bac-teria and percent of Streptomyces sp. were nearly double those foundin the sample taken about 5 feet from the alder seedling. Comparedwith 1965 samples of unvegetated debris, this material outside theinfluence of alder contained twice as much Kjeldahl nitrogen and someammonium and nitrate nitrogen not detected previously.

During the 3 years betweensamplings, the pH decreased by twounits. From moderately alkalinein 1965, the material changed toslightly acidic in 1968, a drop in

2! See footnote 1.

/4/

1

2

4--,

3

pH that can be attributed to intensive leaching. UgoliniV found asimilar but less rapid change of alkaline, uncolonized, unweatheredglacial till in Alaska; under contiguous 17-year-old alder (A. incana(L.) Moench), the pH dropped to 6.8. Alder, in addition to enrichingrocky debris with organic matter and nitrogen, depletes it of carbonatesand progressively acidifies it.

The mechanical analyses are not readily interpretable because theavalanche material was extremely heterogeneous. However, in 1968 therewas indication of decrease in amount of the coarsest material (+20 mesh)and increase in the next two smaller sizes. It was also evident thatthe avalanche surface was more compacted than in 1965. Progressivetextural differences in soil developing on till have been ascribed byUgoliniA/ to surface washing, frost mixing, and mechanical segregationas well as to variations in the original parent material. In the caseof the Little Tahoma avalanche, a factor contributing further to theproportional increase in fine materials was deposition from adjacentmoraines and pumice deposits by strong winds which sweep the slopes ofMount Rainier (fig. 2).

-L

-4-

3J Ugolini, F. C. Soil development and alder invasion in a re-

cently deglaciated area of Glacier Bay, Alaska. In Biology of alder,J. M. Trappe, J. F. Franklin, R. F. Tarrant, and G. M. Hansen (eds.).Northwest Sci. Ass. Fortieth Annu. Meeting,Symp. Proc.1967:115-140,illus. 1968.

4/ S ee footnote 3.

4

The influence of invading alder on soil formation in this rawavalanche deposit was strikingly shown by results from this interimsampling. It further confirms Mitchell's .V conclusions on the impor-tance of Sitka alder as a colonizer that builds nitrogen content andorganic matter of soils on recently glaciated terrain of coastalregions of Alaska.

5/Mitchell, W. W. On the ecology of Sitka alder in the subalpine

zone of south-central Alaska. In Biology of alder, J. M. Trappe,J. F. Franklin, R. F. Tarrant, and G. M. Hansen (eds.). Northwest Sci.Ass. Fortieth Annu. Meeting,Symp. Proc. 1967:45-56, illus. 1968.

5

Table 1.--Chemical, microbial, and mechanical analyses of samples fromLittle Tahoma avalanche deposits near adjacent moraine; oncvendry basis

percent.. 87.3 39.3 50.9

grams.. 94.0 649.0 469.0percent.. 10.6 8.7 9.9

8.7 6.7 6.7

parts per million.. (3/) 2.0 35.0parts per million.. (3/) <.1 <.1parts per million.. (3/) .9 1.5 percent.. .002 .004 .009

percent.. .049 .036 .057

25:1 9:1 6:1

.16 .40 20.550.0 95.0 100.00 3.0 0

37.5 92.5 182.016.0 17.0 33.0

27.74 15.64 16.4019.28 25.26 36.087.73 13.03 9.727.31 10.59 5.844.59 5.74 3.957.13 6.80 5.695.33 4.38 4.37

20.85 18.56 17.95

99.96 100.00 100.00

1965.

C:N ratio

Molds:Total thousands per gram..Penicillia percent..

Mucors percent..

Bacteria:Total thousands per gram..

Streptomyces percent..

Mechanical analysis (-10 mesh):

+20 percent..

+40 percent..

+60 percent..

+80 percent..

+100 percent..

+150 percent..

+200 percent..

-200 percent..

Total

lj Near lower edge of main deposit.9/ Location comparable to sample No. 2,3/ None detected.

Detritus

-10 Mesh

Water pHNitrogen:

NH4

NO2

NO3 Kjeldahl

Tötal carbon

1965sample 21/Sample analysis

1968

Sample 1, Sample 2, aroundaway from 3-year-oldalder?/alder roots

Figure 1.--The avalanche surface wasstill mostly unvegetated in 1968.Emmons Glacier and Little TahomaPeak, the source of the avalanche, are in the background.

Figure 2.--Dust and finesand are blown onto theavalanche surface fromadjacent moraines andpumice deposits by thestrong winds that fre-quently blow about Mount

4 Rainier.

-

3

A.

•

•••

I

A

!••••4•••••■••

ril .

.,.'4 ; . . '...:''. coly., „,

, (VA , r

t ,..i:::. ',.

c

•

•

11. own 0

r.

WARMING UP—Mt Rainier, tat peak in the Northwest, apparently is warm-ing up inside, scientists say. They point to a massive ice breakup on EmmonsGlacier. The mile-long area indicated by dotted line in photo above extends fromthe 10,000 to the 13,000 foot level on the 14,410 - foot slumbering volcano. AGeological Survey scientist says a change in heat within the peak may have caus-ed the shattering, first noticed in February. (AP)

IWnrid Famine

NEVfederacertaitblemsthe in(becat swatch(as Rai

Nev(coupleWashiihandlereciprsellingme, Idromecentramarks

FirA

broacto dlooksdecidcombpanieprodslarge

Th,minooccucomaarenow.onlyregaprier

ItleasrowregtconvieRerhasunfan-op