combining our raw concentration data with depth adjustedestimates of water body volume. In conjunction with loadingestimates, we will then estimate nutrient residence times, togain some sense of nitrogen and phosphorus dynamics in theselakes.

Work in the future will center on modeling of diffusion pro-cesses for nutrients within the lakes. Specifically, we will belooking at the rate of diffusion of ammonia into the upper watersof Lake Fryxell and its conversion to available (and limiting)nitrate. This will permit comparison of internal versus externalloading and will further aid in determining why this lake ismore productive than its oligotrophic neighbor, Lake Hoare.

We wish to thank George Simmons and his students for theirassistance and companionship in the field; and VXE-6 for effi-cient logistics support. We gratefully acknowledge the supportof National Science Foundation grant DPP 81-17644.

References

APHA. 1975. Standard methods for the examination of water and wastewater.(14th ed.) Washington, D.C.: American Public Health Association.

Elston, D.P., and S. L. Bressler. 1981. Magnetic stratigraphy of DVDP drillcores and late Cenozoic history of Taylor Valley, Trans-AntarcticMountains, Antarctica. In L.D. McGinnis (Ed.), Dry Valley DrillingProject. Washington, D.C.: American Geophysical Union.

Parker, B. C., G. M. Simmons, Jr., K. G. Seabung, D. D. Cathey, and F.C.T.

Allnutt. 1982-a. Comparative ecology of plankton communities inseven Antarctic oasis lakes. Journal of Plankton Research, 4(2), 271-286.

Parker, B.C., G.M. Simmons, Jr., R.A. Wharton, Jr., K.G. Seaburg, andF.G. Love. 1982-b. Removal of organic and inorganic matter fromAntarctic lakes by aerial escape of blue-green algal mats. Journal ofPhycology, 18, 72-78.

Rast, W., and G.F. Lee. 1978. Summary analysis of the North American(U.S. Portion) OFCD eutrophication project: Nutrient loading—lake responserelationships and trophic state indices. (U.S. EPA. EPA-G0013-78-008.)Corvallis, Oregon: Corvallis Environmental Research Laboratory.

Simmons, G.M., Jr., B.C. Parker, F.C.T. Allnutt, D.P. Brown, D.D.Cathey, and K.G. Seaburg. 1980. Ecosystem comparison of oasislakes and soils. Antarctic Journal of the U.S., 14(5), 181-183.

Strickland, J.D.H., and T.R. Parsons. 1972. A practical handbook of sea-water analysis. (Bulletin 167 second edition.) Ottawa, Canada: Fish-eries Research Board of Canada.

Toni, T., N. Yamagata, N. Shyu, S. Murata, T. Hashimoto, 0. Mat-subaya, and H. Sakai. 1975. Geochemical Aspects of the McMurdo SalineLakes with special emphasis on the distribution of nutrient matters. In T.Toni (Ed.), Geochemical and Geophysical Studies of Dry Valleys, VictoriaLand, Antarctica. (Mem. Spec. Issue 4.) Tokyo: National Institute ofPolar Research.

Vincent, W. 1981. Production strategies in Antarctic inland waters: PHGto plankton eco-physiology in a permanently ice covered lake. Ecolo-gy, 62(5), 1215-1224.

Vollenweider, R.A. 1968. Scientific fundamentals of the eutrophication oflakes and flowing waters, with particular reference to nitrogen and phos-phorus as factors in eutrophication. (Technical DAS/CSI/68.27.) Paris,France: Organization for Economic Cooperation and Development.

Studies of plant communities of theAntarctic Peninsula near Palmer

Station

V. KOMARKOVA

Institute of Arctic and Alpine Research andDepartment of Environmental, Organismic, and

Population BiologyUniversity of Colorado

Boulder, Colorado 80309

Field operations started on 14 December 1983 and were con-cluded on 25 March 1984; Stan Scott and Miho Toi worked asfield assistants during the entire time. Arthur Harbor opera-lions were again supported from Palmer Station and the Ant-arctic Peninsula operations by RIv Hero. Two sites were visitedwith the French yacht f'Murr (homeport, Brest).

The following sites were sampled during the 1983-1984 sum-mer: Anchorage and Horseshoe Islands; Goudier Island; MinotPoint, Cape Claude, Metchnikoff Point, and Buls Bay on Bra-bant Island; Melchior Islands; Spigot Peak on Danco Coast;Keller Point, Point Thomas, Fildes Peninsula, Suffield Point,Demay Point, and Point Durant on King George Island, andArdley Island, South Shetland Islands; Santos Peak, Leith Coveand Spring Point on Danco Coast: Quinton and Giard Points,Cape Monaco, Biscoe Point, point north of Biscoe Point, andseveral islands and points in Arthur Harbor area on Anvers

Island; Dream Island; Gossler Islands; Joubin Islands; Argen-tine Islands; Almirante Brown Station (Argentina); and BrydeIsland. Sampling of plant communities and their environmentincluding some climatic variables and disturbance continued ateach site; many plots were permanently marked or revisited.

Samples of vascular plants, mosses, and lichens from manyadditional localities along the Antarctic Peninsula were ob-tained from Sally and Jerome Poncet, owners of the Frenchyacht Damien II (homeport, La Rochelle) who discovered thenew southernmost locality of the two native antarctic vascularplants Deschampsia antarctica Desv. and Colobanthus quitensis(Kunth) Bard. on Terra Firma Islands at 62°42'S in MargueriteBay on 16 February 1984. Both plants were growing vigorouslyand reproduced well there in 1984 so that they could probablyoccur farther south if suitable habitats were available (cf. Smith1982). Altogether, twenty-four new localities of vascular plants(14 for D. antarctica, 2 for C. quitensis, and 8 for both species)were reported (Komarkova, S. Poncet, and J . Poncet in prepara-tion) which brings the list of known vascular plant localities inthe Antarctic Peninsula area to 116 (figure 1). Damien II, with sixseasons of experience in the waters of the Antarctic Pensinula,proved very efficient at work requiring frequent landings inshallow waters near shore such as studies of plant or birddistributions; it is available for charter for research purposes.

The most complete environmental monitoring was carriedout on the Stepping Stcne Island, Arthur Harbor area (64°S).Plant and soil temperatures, soil moisture, photosyntheticallyactive radiation, wind speed, and precipitation were recordedby a Campbell Scientific model CR21 micrologger and air tem-perature and relative humidity were recorded by a hygrother-mograph. Plant and soil temperature and soil moisture probes

180 ANTARCTIC JOURNAL

wiq

0.A

Figure 1. Localities of Deschampsia antarctica Desv. and Cob-banthus quitensis (Kunth) Barti. in the Antarctic Peninsula area,Including the localities listed by Greene and Holtom (1971). Fullcircle indicates the presence of both species, left half-full circle thepresence of D. antarctica, and right halt-full circle the presence of C.quitensis. The localities are grouped in the three least glaciatedareas: South Shetland Islands, area between Cierva Point and CapeGarcia, and Marguerite Bay. D. antarctica alone occurs in 58 percentof localities and C. quitensis alone in 3 percent of localities; bothspecies occur in 39 percent of localities. This reflects the consider-ably wider ecological range of D. antarctica. The distribution ofvascular plants within ice-free areas may be determined, for exam-ple, by the radiation receipts of the habitat, geologic substrate,exposure to winds and storms, recent glacier movements, topogra-phy, altitude, and by the animal and human disturbance(Komarkova, S. Poncet, and J. Poncet in preparation).

were located in adjacent Deschampsia- and Colobanthus-domi-nated communities where phenological changes and leaf andplant growth were observed at regular intervals. Two periods ofsoil drought developed at the Deschampsia site (figure 2). Thefirst drought occurred during a period of intensive leaf growth,and was not associated with exceptional air relative humidity,vapor pressure deficit, or wind speed. Die-back of both De-

schampsia and Colobanthus plants was observed, after both soildrought periods (figure 3). Greatest die-back occurred on north-facing rock ledges and other topographically high sites withshallow soil.

The die-back due to desiccation occurred also on Biscoe Pointin the vicinity of Arthur Harbor, but not at Point Thomas, KingGeorge Island (62°S), at the ecological optimum of the two

25 I S 15 2229 5 12 19 re4II

December I January I February I March

Figure 2. Daily maximum soil moisture at 1 centimeter below the surface in the root zone of D. antarctica (solid line and C. quitensis (dashedline). Soil moisture was measured with Delmhorst model 221 gypsum soil moisture blocks. Due to the nature of the polynomials used to convertthe volt output into bars, the range of calculated values is limited to 0.1-15.0 bars even if some voltages indicated values in excess of 15.0 bars(arrows). Precipitation was measured by a Sierra-Misco model 2501 tipping bucket rain gauge recording the number of pulses indicating thetimes at which 1 millimeter of water was collected. Two periods of soil drought developed, in each case after 11 days of no precipitation, between15 and 19 January and 6 and 7 February 1984 on the Deschampsia site. The soil drought was associated with die-back of the monitoredDeschampsia tussock. The monitored Colobanthus cushion did not die-back during the drought while some nearby cushions did; apparently,very small differences in the distribution of moist soil layers and of roots decided whether the plants experienced soil drought or not.

1984 REVIEW 181

Figure 3. D. antarctica tussock (left, 8 centimeters in diameter)which died back during the first period of soil drought on SteppingStone Island between 16 and 19 January 1984. The light (rustybrown) color of the tussock on the left contrasts with the dark greencolor of the tussocks in a small depression on the right side of thephotograph. The amount of current dead phytomass reached 50-90percent in the rusty brown plants; Inflorescences died only in plantswith the highest current dead percentage. Only very few live leavesappeared at the time the photograph was taken (25 February 1984).The recovery of tussocks and cushions, which died back less, wasfaster; few tussocks and cushions did not recover at all In 1984.

vascular plants in the Antarctic Peninsula area. During the soildroughts on Stepping Stone Island, the longest period with noprecipitation lasted only 5 days on Point Thomas. Apparently,near their southern limits, vascular plants are not only stressedby lower mean annual temperature (- 4°C in the Anvers Islandarea vs. -3°C in the South Shetland Islands; Reynolds 1981),but also by significantly greater environmental fluctuations ofthe more continental climate in the south. The recorded soildrought documents only one of several hypothesized eventswhich may produce large patches of dead plants which occurin the southern stands; for example, plants may also be killedby freeze up or, in topographically low positions, by persist-ing snow or water logging (Komarkova, Scott, and Toi inpreparation).

This research was supported by National Science Foundationgrant DPP 82-01047. I would like to thank Captain P.J. Lenie, thecrews of the iIv Hero and U.S. Coast Guard boat Sea 3, and thePalmer Station personnel for their great support.

References

Greene, D.M., and A. Holtom. 1971. Studies in Colobanthus quitensis(Kunth) Bard. and Deschampsia antarctica Desv. III. Distribution, hab-itats, and performance in the Antarctic botanical zone. British Ant-arctic Survey Bulletin, 26, 1-29.

Komarkova, V., S. Poncet, and J . Poncet. In preparation. Two nativevascular plants Deschampsia antarctica Desv. and Colobanthus quitensis(Kunth) Barti.: A new southernmost locality on Terra Firma Islands,Marguerite Bay, and other localities in the Antarctic Peninsula area.

Komarkova, V., S. Scott and M. Toi. In preparation. Summer die-backdue to desiccation of Deschampsia antarctica Desv. and Colobanthusquitensis (Kunth) Bard. on the largest Stepping Stone Island, ArthurHarbor, Anvers Island, Antarctic Pensinula.

Reynolds, J.M. 1981. The distribution of mean annual temperatures inthe Antarctic Peninsula. British Antarctic Survey Bulletin, 54, 123-133.

Smith, R.I.L. 1982. Farthest south and highest occurrences of vascularplants in the Antarctic. Polar Record, 21, 170-173.

182 ANTARCTIC JOURNAL