Vegetation of Amchitka Island, Aleutian Islands, Alaska

DESCRIPTION OF THE ISLAND AND ITS VEGETATION 2 1
meadows. Isolated colonies of Sphagnum, com-
monly 8. capilZaceum and 8. subsecundt6m, occur in
small water-filled depressions in the Enzpetmn~
heath. Typically, this community is best developed
in seepage channels or broader areas of gentle slope
(fig. 16), where sbands composed largely of several
species of Sphagnum limit the invasion of other
plants.
b. Philonotis-Parnassia community (1012).
Soil : Bog; type P, ; pH, 6.5-6.8. Water pH, 6.3-
7.0. Requirement for the development of this com-
munity appears to be a saturated inorganic sub-
strate of very gentle slope through which water
moves. The water is less acid than that of
Sphagnum bogs. The largest observed community
of this type is on sandy soil below the large spring
near Mnkarius Ray, where an almost unbroken mat
of Philonotis covers an area of a hectare or more.
Characteristic species : Philonotis americana and
Parnussia kotaebuei.
Other species : Amblystegium serpens, Carex kel-
loggii, C. Zyngbynei, Cerustium fontanum subsp.
triviale, Dicranella heteromalla, D. subulata, Epilo-
bium sertulatum, Juncus triglumis subsp. albescens,
Jungermnnia sphaerocarpa, Limosella aquutica,
Lophoaia cf. groenlundica, Lupinus nootkatemis,
Platanthera convallariaefolia, P. dilatata, Pogo-
natum urnigemm, Pottia heimii, Saxifraga pz~nc-
tata subsp. insularis, and Veronica serpyllifolia
subsp. humifusa.
Scapania-Nardia-Marsupella community (101).
Soil : Bog ; type P2 ; pH, 6.1-6.8. Although small
colonies of each of the characteristic species occur
in wet areas of the E7npetrum heath, these three liv-
erworts commonly form a distinctive community
that occupies drainage channels and wet areas only
at altitudes above 400 feet. These species also gmw
in the snow-bed community, but there they have
different vascular-plant associates. The brownish
red to bright red of the Scupalzia and Marsupella
and the bright green of the Nardia make the corn-
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/
R~URF, 16.-Spring iss~uing from the margin of a large soligenous I munity conspicuous, even at a distance. The satubog
in a broad valley near Cyril Cove. A wet sedgemeadow rated organic mat formed by this community is as
community is in the foreground, and a Sphagnum bog community
is in the center and background of the picture. At
the time this photograph was made, water temperature in the
spring was 3.3"C, and under the ice of nearby pooh, 0.7"C;
air temperature was -2.3"C. Photographed February 10, 1968.
much as 20 cm thick.
Characteristic species : Scapania paludosa, Nardia
scalaris, and JIarsupelZa emarginata.
Other species: Anthelia juluaea, Aulacomnium
palustre, Bra~h~thecium asperrirnum, Dicranella
Characteristic species : Sphagnum teres, S. sguarrosum,
8. magellan?~mrn, X. compactum, X. pupillosum,
and S. girqensohnii.
Other species: Aulacomnium palustre, Brachytheoium
aspem'rnum, Calypogeia sphagnicola,
Carex anthornantha, C. lyngbyaei, C. pluriflora,
palustris, ~repnnocladus reuolvens, Lycopodium
annotinurn subsp. annotinum, L. sa6inae f o Zium
var. sitcheme, Oncophorz~s u~ahbnbergii, Phihnotis
forttuna, and Smifraga punctata subsp.
insular-is.
6. MARSH EABITAT
Dieranurn amgusturn, Drepanocladus revo7ven3, A marsh on this island can be distinguished from a
Eriophorurn russeo7urn subsp. rufescens, d4nium bog during any season of the year by its abundance of
pseudopunctatum, Philonotis americana, Pingui- sedges and forbs, whereas a bog has a preponderance
cula vulgaris subsp. macrocerus, Plantago ma&- of bryophytes. If the substrate of a marsh is stirred
tima subsp. jumoides, Eiccardia Zatifrons, up, even in winter, it gives off a strong odor of hydrogen
Selagimlla selaginoides, and Siphula ceratites. sulfide. The substrate of a bog however, is virtually
odorless. Probably chemical compounds in the bryophytes
of bogs inhibit the production of hydrogen
sulfide by bacteria.
a. Wet sedge-meadow community (1M21).
Soil: Bog and Half Bog; type 0 ; pH, 5.9-6.2.
Water pH, - 6.3. This is the most abundant com-
munity in the marsh habitat and occurs typically
at the borders of lakes (figs. 8, 17), but it also