combining our raw concentration data with depth adjusted Allnutt. 1982-a. Comparative ecology of plankton communities in estimates of water body volume. In conjunction with loading seven oasis lakes. Journal of Plankton Research, 4(2), 271-286. estimates, we will then estimate nutrient residence times, to Parker, B.C., G.M. Simmons, Jr., R.A. Wharton, Jr., K.G. Seaburg, and gain some sense of nitrogen and phosphorus dynamics in these F.G. Love. 1982-b. Removal of organic and inorganic matter from lakes. Antarctic lakes by aerial escape of blue-green algal mats. Journal of Work in the future will center on modeling of diffusion pro- Phycology, 18, 72-78. Rast, W., and G.F. cesses for nutrients within the lakes. Specifically, we will be Lee. 1978. Summary analysis of the North American (U.S. Portion) OFCD eutrophication project: Nutrient loading—lake response looking at the rate of diffusion of ammonia into the upper waters relationships and trophic state indices. (U.S. EPA. EPA-G0013-78-008.) of Lake Fryxell and its conversion to available (and limiting) Corvallis, Oregon: Corvallis Environmental Research Laboratory. nitrate. This will permit comparison of internal versus external Simmons, G.M., Jr., B.C. Parker, F.C.T. Allnutt, D.P. Brown, D.D. loading and will further aid in determining why this lake is Cathey, and K.G. Seaburg. 1980. Ecosystem comparison of oasis more productive than its oligotrophic neighbor, Lake Hoare. lakes and soils. Antarctic Journal of the U.S., 14(5), 181-183. We wish to thank George Simmons and his students for their Strickland, J.D.H., and T.R. Parsons. 1972. A practical handbook of sea- assistance and companionship in the field; and VXE-6 for effi- water analysis. (Bulletin 167 second edition.) Ottawa, Canada: Fish- cient logistics support. We gratefully acknowledge the support eries Research Board of Canada. of National Science Foundation grant DPP 81-17644. Toni, T., N. Yamagata, N. Shyu, S. Murata, T. Hashimoto, 0. Mat- subaya, and H. Sakai. 1975. Geochemical Aspects of the McMurdo Saline Lakes with special emphasis on the distribution of nutrient matters. In T. Toni (Ed.), Geochemical and Geophysical Studies of Dry Valleys, Victoria References Land, . (Mem. Spec. Issue 4.) Tokyo: National Institute of Polar Research. APHA. 1975. Standard methods for the examination of water and wastewater. Vincent, W. 1981. Production strategies in Antarctic inland waters: PHG (14th ed.) Washington, D.C.: American Public Health Association. to plankton eco-physiology in a permanently ice covered lake. Ecolo- Elston, D.P., and S. L. Bressler. 1981. Magnetic stratigraphy of DVDP drill gy, 62(5), 1215-1224. cores and late Cenozoic history of Taylor Valley, Trans-Antarctic Vollenweider, R.A. 1968. Scientific fundamentals of the eutrophication of Mountains, Antarctica. In L.D. McGinnis (Ed.), Dry Valley Drilling lakes and flowing waters, with particular reference to nitrogen and phos- Project. Washington, D.C.: American Geophysical Union. phorus as factors in eutrophication. (Technical DAS/CSI/68.27.) Paris, Parker, B. C., G. M. Simmons, Jr., K. G. Seabung, D. D. Cathey, and F.C.T. France: Organization for Economic Cooperation and Development.

Studies of communities of the Island; Dream Island; Gossler Islands; Joubin Islands; Argen- tine Islands; Almirante Brown Station (Argentina); and Bryde Antarctic Peninsula near Palmer Island. Sampling of plant communities and their environment Station including some climatic variables and disturbance continued at each site; many plots were permanently marked or revisited. Samples of vascular , , and lichens from many V. KOMARKOVA additional localities along the Antarctic Peninsula were ob- tained from Sally and Jerome Poncet, owners of the French Institute of Arctic and Alpine Research and yacht Damien II (homeport, La Rochelle) who discovered the Department of Environmental, Organismic, and new southernmost locality of the two native antarctic vascular Population Biology plants Desv. and quitensis University of Colorado (Kunth) Bard. on Terra Firma Islands at 62°42S in Marguerite Boulder, Colorado 80309 Bay on 16 February 1984. Both plants were growing vigorously and reproduced well there in 1984 so that they could probably occur farther south if suitable habitats were available (cf. Smith Field operations started on 14 December 1983 and were con- 1982). Altogether, twenty-four new localities of vascular plants cluded on 25 March 1984; Stan Scott and Miho Toi worked as (14 for D. antarctica, 2 for C. quitensis, and 8 for both species) field assistants during the entire time. Arthur Harbor opera- were reported (Komarkova, S. Poncet, and J. Poncet in prepara- lions were again supported from Palmer Station and the Ant- tion) which brings the list of known localities in arctic Peninsula operations by RIv Hero. Two sites were visited the Antarctic Peninsula area to 116 (figure 1). Damien II, with six with the French yacht fMurr (homeport, Brest). seasons of experience in the waters of the Antarctic Pensinula, The following sites were sampled during the 1983-1984 sum- proved very efficient at work requiring frequent landings in mer: Anchorage and Horseshoe Islands; Goudier Island; Minot shallow waters near shore such as studies of plant or bird Point, Cape Claude, Metchnikoff Point, and Buls Bay on Bra- distributions; it is available for charter for research purposes. bant Island; Melchior Islands; Spigot Peak on Danco Coast; The most complete environmental monitoring was carried Keller Point, Point Thomas, Fildes Peninsula, Suffield Point, out on the Stepping Stcne Island, Arthur Harbor area (64°S). Demay Point, and Point Durant on King George Island, and Plant and soil temperatures, soil moisture, photosynthetically Ardley Island, South Shetland Islands; Santos Peak, Leith Cove active radiation, wind speed, and precipitation were recorded and Spring Point on Danco Coast: Quinton and Giard Points, by a Campbell Scientific model CR21 micrologger and air tem- Cape Monaco, Biscoe Point, point north of Biscoe Point, and perature and relative humidity were recorded by a hygrother- several islands and points in Arthur Harbor area on Anvers mograph. Plant and soil temperature and soil moisture probes 180 ANTARCTIC JOURNAL 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). Full circle indicates the presence of both species, left half-full circle the presence of D. antarctica, and right halt-full circle the presence of C. quitensis. The localities are grouped in the three least glaciated areas: South Shetland Islands, area between Cierva Point and Cape Garcia, and Marguerite Bay. D. antarctica alone occurs in 58 percent of localities and C. quitensis alone in 3 percent of localities; both species occur in 39 percent of localities. This reflects the consider- ably wider ecological range of D. antarctica. The distribution of vascular 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 and plant growth were observed at regular intervals. Two periods of soil drought developed at the Deschampsia site (figure 2). The first 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 soil drought periods (figure 3). Greatest die-back occurred on north- facing rock ledges and other topographically high sites with shallow soil. The die-back due to desiccation occurred also on Biscoe Point in the vicinity of Arthur Harbor, but not at Point Thomas, King

wiq George Island (62°S), at the ecological optimum of the two

0 .A

25 I S 15 22 29 5 12 19 re 4 II 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 (dashed line). Soil moisture was measured with Delmhorst model 221 gypsum soil moisture blocks. Due to the nature of the polynomials used to convert the 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 the times at which 1 millimeter of water was collected. Two periods of soil drought developed, in each case after 11 days of no precipitation, between 15 and 19 January and 6 and 7 February 1984 on the Deschampsia site. The soil drought was associated with die-back of the monitored Deschampsia 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 vascular plants in the Antarctic Peninsula area. During the soil droughts on Stepping Stone Island, the longest period with no precipitation lasted only 5 days on Point Thomas. Apparently, near their southern limits, vascular plants are not only stressed by lower mean annual temperature (- 4°C in the Anvers Island area vs. -3°C in the South Shetland Islands; Reynolds 1981), but also by significantly greater environmental fluctuations of the more continental climate in the south. The recorded soil drought documents only one of several hypothesized events which may produce large patches of dead plants which occur in the southern stands; for example, plants may also be killed by freeze up or, in topographically low positions, by persist- ing snow or water logging (Komarkova, Scott, and Toi in preparation). This research was supported by National Science Foundation grant DPP 82-01047. I would like to thank Captain P.J. Lenie, the crews of the iIv Hero and U.S. Coast Guard boat Sea 3, and the Palmer 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 native Figure 3. D. antarctica tussock (left, 8 centimeters in diameter) vascular plants Deschampsia antarctica Desv. and Colobanthus quitensis which died back during the first period of soil drought on Stepping (Kunth) Barti.: A new southernmost locality on Terra Firma Islands, Stone Island between 16 and 19 January 1984. The light (rusty Marguerite Bay, and other localities in the Antarctic Peninsula area. brown) color of the tussock on the left contrasts with the dark green Komarkova, V., S. Scott and M. Toi. In preparation. Summer die-back color of the tussocks in a small depression on the right side of the due to desiccation of Deschampsia antarctica Desv. and Colobanthus photograph. The amount of current dead phytomass reached 50-90 quitensis (Kunth) Bard. on the largest Stepping Stone Island, Arthur percent in the rusty brown plants; Inflorescences died only in plants Harbor, Anvers Island, Antarctic Pensinula. with the highest current dead percentage. Only very few live leaves Reynolds, J.M. 1981. The distribution of mean annual temperatures in appeared at the time the photograph was taken (25 February 1984). the Antarctic Peninsula. British Antarctic Survey Bulletin, 54, 123-133. The recovery of tussocks and cushions, which died back less, was Smith, R.I.L. 1982. Farthest south and highest occurrences of vascular faster; few tussocks and cushions did not recover at all In 1984. plants in the Antarctic. Polar Record, 21, 170-173.

182 ANTARCTIC JOURNAL