Great Basin Naturalist Volume 36 Number 3 Article 1 9-30-1976 A taxonomic and ecologic study of the riverbottom forest on St. Mary River, Lee Creek, and Belly River in southwestern Alberta, Canada Robert K. Shaw Cardston, Alberta, Canada Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation Shaw, Robert K. (1976) "A taxonomic and ecologic study of the riverbottom forest on St. Mary River, Lee Creek, and Belly River in southwestern Alberta, Canada," Great Basin Naturalist: Vol. 36 : No. 3 , Article 1. Available at: https://scholarsarchive.byu.edu/gbn/vol36/iss3/1 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. The Great Basin Naturalist Published at Provo, Utah, by Brigham Young University Volume 36 September 30, 1976 No. 3 A TAXONOMIC AND ECOI.OGIC STUDY OF THE RIVERBOTTOM FOREST ON ST. MARY RIVER, LEE CREEK, AND BELLY RIVER IN SOUTHW^ESTERN ALBERTA, CANADA Robert K. Shawi Abstr.\ct. — The riverbottom forest community of St. Mary River. Lee Creek, and Belly River in southvvestern Alberta. Canada, is a unique ecological entity characterized by poplar species hav- ing their major Alberta distribution along these streams. Stands in the community are dominated by three tree species, six shrub species, and nine herb species. Establishment of the community is dependent on climate and substrate; destruction is the result of progressive lateral stream-flow erosion. Soils are sandy loams above gravel, with pH values of 1.1 to 8.0 and soluble salt concen- trations of 176 to 458 parts per million. Trees in mature stands averaged 23.0 cm in diameter and 40 3'ears in age; ma.ximum tree age was 250 years. The vascular flora consists of 291 species of whicb 41 are woody and 250 herbaceous. One species {Prunus nigra Ait.) new to Alberta and range extensions for 12 species are cited. There are no true community endemic species. Recreational and livestock-raising uses are present community modifiers. Fire is not important in current forest dynamics. The riverbottom forest community of about 1,235 km- of northwestern Montana southwestern Alberta, Canada, is usually and southwestern Alberta. less than 0.8 km in width and occurs on Monthly water flow in all three streams only certain lengths of each stream. It has varies widely throughout the year. From been utilized for pasture and, to a minor late July through autumn and winter the extent, for firewood and timber, leaving flow is fairly constant, but during March much of the woodland free from excessive warmer weather causes snow melt in the disturbance. This study treats several as- foothills and on the lower mountain slopes pects of the riverbottom forest community to increase stream flow. The most rapid including the vascular flora, community melting of deep mountain snow occurs in stratification and composition, successional late May and early June. This coincides patterns, seasonal aspect, climate, geog- with the season of highest precipitation raphy, geology, and soils. when stream flow is swollen to its max- St. Mary River, Lee Creek, and Belly imum, which is four to five times the River originate in alpine tundra (ele- winter flow rate. Stream flow generally vation 2,000-3,200 m) on the Lewis Range peaks rapidly in late May or earlj^ June of the Rocky Mountains in Glacier Na- followed by a rapid decline throughout tional Park, Montana (Fig. 1). From al- July. Maximum flow in any year seldom pine tundra these streams flow northeast persists for more than 24 hours. Irrigation into the Province of Alberta, Canada, water is in low demand at the high run- through montane forest and aspen park- off season, and the six small weirs and land into the treeless stretches of fescue diversions on the three streams exert little prairie (elevation 900-1,400 m) where, control on downstream flooding. In spite along the stream courses, the poplar-domi- of these uses, near normal flow does pre- nated riverbottom forest community be- vail in the three streams in all months comes a unique ecological entity (Fig. 2). of the year except July, August, and St. Mar\' River drains about 3,440 km-, September. Lee Creek about 290 km-, and Belly River Pollution of the waters varies. No in- 'Box 364, Cardston, Alberla, Canada. 243 244 GREAT BASIN NATURALIST Vol. 36, No. 3 Porcupine Hills Monarch 1580 m k» Oldman River I 17 km • Fort Lethbr^dge M Macleod 896 m 950 m Standoff Waterton Belly River Waterton St. Mary Reservoi] rj-^'SI Reservoir 1113 m Cardston 1151 m^ • Mountain St. Mary View Lee Creek River 1312 m Zi Milk River Ridge 1433 m Alberta, Canada Montana, U.S.A. Lewis Range 3200 m Fig. L Streams of soiifhwoslcrii Allx-itii. Cariiidii. 'Ilic mnioi- ci olof^ic and taxoiiotnu stiidv •^ites are niimberorl 1 through 10. September \'^76 SHAW: HIV1,HIU)TT()M IX)UEST 245 Fig. 2. Site 4 on St. Mar\' River, a typical climax stand of riverbottom forest on the second terrace. The background farmland is on the third terrace, and the foreground road crosses the fourth terrace grassland. (lustrial wastes reach these streams, al- brother, Mike, for being a very willing though municipal sewage and some agri- field crew during the study. cultural feedlot effluent cause local prob- lems. Early snowmelt combined with per- Geology .\nd Geogr.^phy colation and leaching of water through old vegetation and manure on the up- The headwaters of the three streams lands causes discoloration and objec- originate on the Continental Divide over tionable odor in the water during March geological formations of the Belt Series and April of each year. High runoff in the Lewis Range of the Rocky Moun- from rain and melting snow in late May tains (Wyatt 1939). These strata, nearly and early June produces a high particulate all of sedimentary origin, were formed content in the water at this time. For the during the Proterozoic Era of 510,(300,000 rest of the year stream water in St. Mary years ago when much of western Alberta, River, Lee Creek, and Belly River tends eastern British Columbia, Montana, and to be clear, clean, and free from con- Idaho were covered by a shallow^ sea. taminants. These rocks, with a maxinnmi thickness of more than 6,100 m, are in the form of Acknowledgments a large syncline, the east edge of which forms the Lewis Range. The greatest thick- The author wishes to extend his thanks nesses of limestone .show numerous fossils to all those who have helped make this of calcareous algae and primitive marine work possible. Gratitude is expressed to [ilants. Dr. S. L. Welsh, Dr. J. R. Murdock, and The mountains themselves, of more re- Dr. C. Lynn Hayward of Brigham Young cent origin, are about 58.000,000 years University for their counsel and guidance f)ld. Thev resulted when tremendous during the course of this study. The use cru'^tal forces, principally from the west, of the Herbarium of Brigham Young Uni- w^ere directed against the geosyncline. The versity and the assistance rendered by its Proterozoic rocks were uj)lifted and moved curator, Dr. S. L. Welsh, in identifying some 80 km to the east where they were plant specimens are gratefully acknowl- warped into a great anticline, the Lewis edged. Overthrust, which overlies the younger The author also wishes to express his Cretaceous shales and sandstones of the appreciation to his wife, Shirley, and his plains. It is because of the Lewis Over- 246 GREAT BASIN NATURALIST Vol. 36, No. 3 thrust that there are no significant foot- Much of southwestern Alberta is ve- hills on the east side of the Lewis Range. neered with glacial deposits (Wyatt During Miocene and Pliocene time the 1939). Glaciation was general over most mountains were deeply eroded by streams. of the area. There is also widespread dis- Several thousand meters of Belt rocks tribution of reworked glacial deposits as were removed during the course of valley well as alluvial and lacustrine deposits formation. Near the close of Pliocene time transported by rivers and creeks. Retreat the climate cooled, vegetation disappeared, of the glaciers is presumed to have oc- and mountain glaciers formed from the curred for the last time about 9,000 years snow and began to move down the stream- ago (Dyson 1949). caned valleys where they met the con- Soils on the prairie section of south- tinental glaciers advancing from the western Alberta are generally fertile. As- north. pen parkland and some adjacent fescue The prairie section of St. Mary River, prairie are in the black soil zone and Lee Creek, and Belly River flows through east of this are the shallow black soils and over a variety of consolidated and which grade gradually into dark brown unconsolidated deposits, from the trans- soils of the mixed grass prairie and short- ported Belt series rocks of Proterozoic grass plains. The dark brown and most time to the more recent Cretaceous series. of the shallow black zones underlie tree- The geological formations which occur at less prairie. The soils along the river and the surface or immediately below the un- creek bottoms are of alluvial deposition in consolidated deposits the plains and and some, still liable to frequent flood- foothills zone of southwest Alberta are ing, are quite variable in texture and Cretaceous and Tertiary in age. A large utilization (Wyatt 1939).