File:Contributions from the Botanical Laboratory, vol. 9 (1892) (20499981338).jpg

Title: Contributions from the Botanical Laboratory, vol. 9
Identifier: contributionsfro09univ (find matches)
Year: 1892 (1890s)
Authors: University of Pennsylvania. Botanical Laboratory
Subjects: Botany; Botany
Publisher: Philadelphia : University of Pennsylvania Press
Contributing Library: Penn State University
Digitizing Sponsor: Lyrasis Members and Sloan Foundation

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1' h 1 I 380 Vegetation of some Southern Provinces of Soviet Russia Zone VII. Subalpine (1700 m.). Above Gvileti lies a subalpine region of great interest and beauty (1700- 2200 m.). Small trees, chief among which is the birch, alternate with flower- covered meadows bounded above by Rhododendron and alpine pastures. At Gvileti, Betula mddeana climbs to 2400 m. and gets down to 1700 m., occurring, therefore, in both the alpine and subalpine regions (PI. XX, Phot. 7). The more typical birch of the alpine zone is Betula pubescens, I am not quite certain in regard to a third kind of birch, B, pubescens var. raddeana, occurring at Gvileti. It appears to differ from both the pubescens and raddeana species and therefore was identified as a third form, though it may be identical with one or the other of the two species after which it is named. An interesting tree, of which I saw only one specimen in these higher mountain valleys, is the maple, Acer trautvetteri, which was growing at 2000 m. Radde says that this species may reach the tree line. Here at Gvileti it is near the tree line, but I never found it there in the Minor Caucasus, where it is very abundant, occurring just below the open subalpine woods of birch. Sorbus aucuparia begins to make its appearance at 1600 m., getting up into the alpine region at 2400 m. (PL XX, Phot. 7). This small tree is of very wide distribution in the mountains of the Soviet Union from the Crimea to Eastern Turkestan. It is a companion to the birch. Whether to regard the two as alpine or subalpine is purely a matter of defining the limits of these zones in that particular region where we happen to be at the time. In the Crimea, neither of these two high altitude trees plays a prominent part in the plant life of the mountains, they occur only sparingly, while in the Minor (South) Caucasus (Bakuriani) they grow in great abundance, form the tree line, and on certain slopes occur at high altitudes to the exclusion of all other arboreal forms. Usually, the tree line of birch and Sorbus makes a convenient upper limit of the subalpine zone, but where meadows of tall, showy, subalpine plants, such as Scabiosa, Del- phinium, Cephalaria and Epilobium, grow above the birches, then, naturally, we cannot regard the latter as delimiting the alpine and subalpine flora; furthermore, where the birches get so far above the fields of herbaceous succulents as to mingle with Rhododendron, as here at Gvileti, they become alpine, for their associates are not only Rhododendron but such other truly alpine forms as Antennaria and Sibbaldia. One other tree occurring here at 2000 m., though not abundantly, is Salix caucasica. The trail at Gvileti, with Mount Kasbek and its glacier constantly in view, rises but little above 2000 m. before it descends again to go into the rocky gorge at the head of which is the terminus of the glacier. The trail reaches its highest point in a field of flowers of great luxuriance and beauty. This sub- alpine meadow extends from 2000 to 2200 m., and is almost entirely covered with a tall rank growth of herbaceous plants: very little grass is visible, and lOURNAL OF ECOLOGY Vol. XIX, Plate XIX
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Phot. 4. Phragmites communis at Gvileti.

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