Report of the scientific results of the voyage of S.Y. "Scotia" during the years 1902, 1903, and 1904, under the leadership of William S. Bruce

Field: Earth and Planetary Sciences (Physical Sciences)

Ill 5 almnd.int in tin->outh.and winter temp, ratines, at least in the outermost south polar nonius, ne^leeting for the moment comparative latitudes, are not more m than in the nitrth.Tin-real explanation is pr<>liul>ly to be found in the short and inadequate Antarctic Mimmer, with its remarkably low temperatures.Thus, for example, at the South Orkneys, in 60 44' S., the mean <>f the summer months (I>eeeml>er, January, and February) is liarely -'J-F., and in no month does the mean rise to 33 F., while the ni--aii of the warmest day in 1903-04 was only 377 K. ; at Snow Hill Island, LouisPhilippe Laud (64* 24' S.), the mean of the warmest month (January) was found to be only 30'38 e R, while at Cape Adare, Victoria Land, in 71" 18' S., the summer mean is 30 '4 F.At 77 50' S., 166 44' E., in MoMurdo Sound, the Discovei-y found that the mean summer temperature was 2P4 F., and the mean of the warmest month, December, , 1 1 .;r.These temperatures may be compared with those of the Arctic regions.Thus at Spit.-liergen (79 53' N.) the mean temperature of July (the corresponding month to January in the south) is as high as 41 '5 F., while in Franz Josef Land, in over 80 N., it is not lower than 35'G F. in the same month.The mean of the Spitsbergen summer (June, July, and August) is 37'1, contrasted with the corresponding mean given above iic South Orkneys, scarcely 32 F. Examples could thus be multiplied, but all would lirinjr out the same important point that while the Arctic summer mean is well above 32" F., the Antarctic summer mean is practically always lielow.This remarkably cold Antarctic summer acts in two ways upon plant life : firstly, the winter snow lies late on the ground all the later as the summer is a cloudy and somewhat sunless period, and December is well advanced before the majority of available sites are laid bare, while m February the winter again begins 1 ; secondly, and this is the chief reason, it is doubtful if a flowering plant could obtain the requisite amount of heat needed for its various life functions even to reach the flowering stage, while the maturation of its fruit would be next to impossible.In fact, one could with much truth say that the Antarctic summer is but an astronomical conception : those who have experienced it know well how little reality it has.Doubtless, then, in this want of a season of growth lies a quite adequate explanation of the poverty of the south polar vegetation, but I think that there is also another adverse influence at work.Even supposing that a species did obtain a footing on Antarctica, as is not impossible in the lands nearest Fuegia, considering the narrowness of Drake Strait, its continued existence would be at once menaced by the presence of the myriads of penguins which occupy almost ev.\\ bare spot of ground during the nesting and breeding season.There is no parallel in the north t-i these penguins and the power they would have in destroying any vegetable 1 Contrast thU with tin-north, where, for example, at the northern part of the east court, of Greenland, the land is clear of now from May or early June until September, date* which would corroipond in the tooth to ; nber to March.life.Almost every spot where a plant might obtain a hold is covered with these birds in the proportion of at least one to a square yard, and nothing escapes their insatiable curiosity or fails to be examined with their beaks, while in a few weeks' time such a rookery is in an indescribable state of filth, being entirely covered with several inches of mud and manure through which the penguins are incessantly tramping hither and thither ; circumstances which would render plant life quite out of the question.It is true that here and there one finds a small expanse even as much as an acre I have once seen of moss-covered rocks which by successive years' growth are covered with 6 to 8 inches of vegetable soil, but these are spots much less accessible from the sea, and are very seldom suitable for rookeries which is, of course, the sole condition under which this continuous growth of moss from year to year could continue.In such spots one might look, though in vain, for flowering plants, and perhaps in consequence conclude that the influence of the penguins, though potentially inimical to vegetable life, has never cause to operate, at least against flowering plants.But it must be noted that these moss formations, though in many respects suitable for phanerogamic plant life, are yet always very late in losing their winter snow, and generally lie in sheltered places where wind-carried seeds would be little likely to arrive.That seeds of Fuegian species of phanerogams occasionally reach Graham Land and the adjacent South Shetland and South Orkney Islands is more than probable, considering the prevalence of winds from the north of west in that region : it is even possible, though far less likely, that wind-carried seeds from Kerguelen and Heard Islands occasionally alight on parts of the coasts of Wilkes Land.Most important in relation to the possible wind transport of Fuegian species to Antarctica is the discovery by Dr F. E. Fritsch of pollen grains of Podocarpus among the algae found in a patch of red snow in the South Orkneys.The nearest land from which these pollen grains could have come is southern South America, where several species of Podocarpus occur in Chili, some at high altitudes, and so more likely to have their pollen carried by the wind.I cannot suggest any way in which these pollen grains can have reached the South Orkneys other than by wind carriage, and their presence seems indisputable proof of the possibility of this occurring.In this relation it is noteworthy that Dr Fritsch believes " that the nature of some of the Antarctic freshwater plankton points to wind carriage over considerable distance, although the available data are not sufficient."The likelihood of the transport of seeds by birds is lessened by the fact of there being only one true land bird (Chionis alba] in the Antarctic, but it seems quite probable that seeds and spores are occasionally carried adhering to the feet and feathers of such wandering birds as the southern black-backed gull, the skua, and the giant petrel, which range from sub-antarctic to Antarctic lauds.Almost everywhere that snow-free land occurs on the coasts of Antarctica in summer, innumerable birds find nesting-places, and these are the places where or near where most of the vegetation occurs.As regards floating ice, I do not think that in the Antarctic it ever acts as an agency in the dispersal of species.I ili.it the c.inspieiiiiug absence of driftwood on Antar.ti,-!ii.that there is little likrliliiH.il of wave-carried seeds being stranded.' The contrast with the shont of MOM parts of tin-Antic regions is certainly great in thi> n-p.-ct.Numerous stretches of the coasts of Spitsbergen have almost the appearance of timber-yards willi their acres of timber-stacked beaches.During eight iths at tli.' Smith Orkneys we found only a single small piece of driftwood.But this absence of driftwood can \-explained on two grounds: firstly, to currents sweeping past rather than -inking the shores of Antarctica, except perhaps the north-west of Graham Land and the South Shetlands ; and, secondly, to an absence of driftwood in the waters of the Southern < trean.Most of the Arctic driftwood is brought down by the Siberian rivers and the Mackenzie River in flood.A large amount is thus swept into a confined sea.For the Southern Ocean there are no such sources of supply, while the little timber that is swept into the sea is negligible in that vast extent of water.Nor do I think that seeds and spores brought on driftwood and wreckage to Antarctic coasts would stand any chance of stranding on a locus favourable for growth, even supposing they had survived the voyage, and that is most unlikely.It is therefore not by reason of their isolation alone that the south polar regions have next to no phanerogamic vegetation, but because they are unsuited in one way or another to support it.If such a modest biological station, as I have advocated above, should be instituted, it would be a matter of extreme interest to attempt to cultivate on certain of the mossy oases various species of hardy Arctic plants, such as Papaver radio i tun i. Ranunculus sulphureus, Cerastium alpinum, Saxifraga uppositifolia, etc. etc., which all prosper and produce seed in Spitsbergen.*Dr Skottsberg, of the Swedish Antarctic Expedition, considers that the formidable Antarctic winds must be another unfavourable condition for higher plant life.*While fully admitting the strength of the winds that sweep over certain localities the greater part of the year, I do not think that they could have an inimical influence on any possible vegetation, partly because there are always certain sheltered spots, but largely because the Antarctic summer is a relatively calm period, while the winds of winter could of course have no prejudicial influence through the covering of snow.1