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abundant active dunes adapted adenophylla advancing dune advancing lee slope Agropyrum altitude Ammophila Ammophila dune Andropogon Arctostaphylos Artemisia basswood basswood dunes beach dunes Beaver island bluffs buried Cakile Calamagrostis Canadensis chiefly Cnicus coast common complex coniferous forests Corispermum Cornus cottonwood cottonwood dune dune advances dune flora dune formation Dune Park dune-complex dune-formers Elymus Elymus Canadensis embryonic dunes encroach established dunes exposed extensive foreground fossil beaches germinate Glen Haven grass gravel grow growth heath herbs hydrophytic hydrophytic beach Juniperus Juniperus communis Lake Michigan leeward less longifolia lower beach mesophytic middle beach North Manitou island northward oak dunes perched dunes pine plant societies plant species Prunus region river bottom Salix sand dunes seen shore shown in fig shrubs soil south end steep terraces tion topographic forms trees undrained swamps upper beach vegetative propagation wandering dunes water level willows wind wind-sweep windward slopes xerophytic zone
Page 119 - WILLKOMM, M.: Die Strand- und Steppengebiete der iberischen Halbinsel und deren Vegetation.
Page 110 - There are all gradations between a simple moving dune and a moving landscape ; the latter may be called a dune-complex. The complex is a restless maze, advancing as a whole in one direction, but with individual portions advancing in all directions. It shows all stages of dune development and is forever changing.
Page 19 - ... important function which dune plants perform for other plants is in the contribution of organic food materials to the soil. The oxidation or removal of decaying vegetation is so complete on the newer dunes that the accumulation of humus is not important. On the more established dunes the mold becomes deeper and deeper, and, after the lapse of centuries, the sandy soil beneath may become buried so deeply that a mesophytic flora is able to establish itself where once there lived the tenants of...
Page 3 - The ecologist employs the methods of physiography, regarding the flora of a pond or swamp or hillside not as a changeless landscape feature, but rather as a panorama, never twice alike. The ecologist, then, must study the order of succession of the plant societies in the development of a region, and he must endeavor to discover the laws which govern the panoramic changes. Ecology, therefore, is a study in dynamics.
Page 102 - Any dune may become rejuvenated if the physical conditions are favorable, but the 375 great majority of rejuvenated dunes are developed from established coniferous dunes ; hence this type is discussed in connection with the evergreen series. The coniferous forests that develop on the windward slopes near the lake are peculiarly subject to destruction. The slightest change in the physical conditions is often sufficient to bring about the destruction of a FIG. 24. — Beginnings of a heath on a fossil...
Page 59 - In some places it is so thick and green as to look almost like a field of grain from a distance ; yet even here, the luxuriant growth is only in the protected places, and none at all is found in the most exposed situations. The reasons for the scanty plant life on the exposed portions of the dune-complex are not far to seek. First of all it is not due to the scarcity of water in the soil. Even after a long period of drought in summer, the sand is cool and moist at a short distance below the surface....
Page 118 - KURTZ, F.: Bericht über zwei Reisen zum Gebiet des oberen Rio Salado (Cordillera de Mendoza), ausgeführt in den Jahren 1891-1893. Verhandl. Bot. Ver. Prov. Brandenburg 35 : 95. 1893. LAMB, FH: The sand dunes of the Pacific coast. The Forester 3:94. 1897LITWINOW, DJ: Ob okskoi florje w Moskowskoi gubernii. Material)' k posnaniju fauny i flory Rossijskoi Imperii.
Page 22 - ... discarded and his article taken as the basis of the presentation of the subject. From the ecologic sub-divisions worked out by Dr. Cowles, the following have been selected as fairly representing characteristic conditions in the area considered. I. THE LOWER BEACH. "The lower beach has been defined as the zone of land washed by the waves of summer storms. It might also be defined as that portion of the beach which is devoid of vegetation.
Page 112 - Coniferous forests also occur on sterile barrens and in bottoms, where the conditions are also unfavorable for deciduous forests. A slight change in the physical conditions may bring about the rejuvenation of the coniferous dunes, because of their exposed situation. Rejuvenation commonly begins by the formation of a wind-sweep; the vegetation on either hand is forced to succumb to sand-blast action and gravity.
Page 27 - The protective influence exerted by piles of debris is finely shown on the beach at North Manitou island. The upper beach along the south shore of the lake is usually very sandy and comparatively free from driftwood, while the North Manitou beaches are composed chiefly of gravel and shingle with heaps of driftwood piled about in the greatest confusion. The North Manitou flora is one of marked luxuriance, compared with the more southern type, and many mesophytic species are able to get a foothold...