Plant succession in saline areas of Saskatchewan
Date
1960-04
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Doctoral
Abstract
Studies have not previously interrelated in detail the vegetation
and soils in areas of soluble salt accumulation in North America.
The reports which have appeared have been limited to general descriptions
and distribution of communities and their general relationship to
soil characteristics. Two brief accounts of this nature have
considered Canadian vegetation.
The surface glacial deposits in the northern Great Plains
grassland have favored the development of saline areas by providing a
source of salts and in restricting the flow of runoff water out of
the area. Evaporation from shallow "kettles" and depressions in
glacial lake beds and drainage channels has resulted in the gradual
accumulation of soluble material from the till. Approximately 2
percent (over 1,000,000 acres) of the settled areas of Saskatchewan
is affected by this process. The concentration of salts is sufficient
so that a large part of this is not cultivated or utilized in any way.
Elsewhere, lower salinity permits cropping, but with poor results.
Some areas are periodically affected by movement of the salt within
the soil. The relatively level surface and topographic position of
these areas provide a situation where irrigation would be practical
in the absence of saline conditions.
The purposes of the present study were to relate characteristics
of the native vegetation within such areas in Saskatchewan to conditions within the soil and to ascertain the course of parallel changes taking
place in soil and vegetation during plant succession. This information
is of value in planning for proper land use, particularly with respect
to the potential value of marginal areas as irrigated cropland.
The area of study was within the major agricultural region of
Saskatchewan, south of a line drawn from Melfort to the Alberta
Boundary through North Battleford and to the Manitoba Boundary
near Moosomin. About 270 saline areas were observed and/or sampled
during three summers (1957-59). This enabled a comparison of saline
conditions and native vegetation throughout the entire region.
A recent classification of salty soil distinguishes between
"saline", "nonsaline-nonalkali", "nonsaline-alkali", and "saline-alkali"
(U. S. Salinity Laboratory 1954). Saline soils have an electrical
conductivity of the saturation extract in excess of four mmhos./cm.
This is similar to that of the saline-alkali group, but greater than
the nonsaline-nonalkali and nonsaline-alkali. The exchangeable-sodium-percentage of saline and nonsaline-nonalkali soils is less than
15, while it exceeds this value in the nonsaline-alkali and saline-alkali
soils. The pH of saline soil, like saline-alkali, is usually
8.5 or less, while that of nonsaline-alkali soil exceeds 8.5. Nonsaline-
nonalkali soil ranges from slightly acid to slightly alkaline
in reaction. Saline soil is similar to saline-alkali in most respects,
except that sodium comprises a higher proportion of the soluble
cations in the latter, while sodium and the alkaline-earth carbonates
are prominent in the former. Many papers have used the term "alkali"
in a broader sense than indieated above. Undoubtedly much of this
work relates to saline soil, but it is often difficult to distinguish between the types of salty soils because of lack of uniformity in
definition in many previous papers. In the present investigation
the term "saline" is used in the narrower sense, as defined above.
This investigation was conducted while the author was a graduate
student in the Department of Plant Ecology at the University of
Saskatchewan. It was made possible through the provision of funds
by the Saskatchewan Research Council and the Saskatchewan Agricultural
Research Foundation. Plants collected during the investigation were
placed in the W. P. Fraser Memorial Herbarium (SASK.) at the
University of Saskatchewan. Uncertain identifications were checked by
the staff of the herbarium of the Canada Department of Agriculture
(DAO) at Ottawa.
The author expresses his gratitude to members of the Soil surveys
of the Saskatchewan and Canada Departments of Agriculture and the
Department of Soil Science, particularly Dr. D. A. Rennie, for advice,
criticism, and assistance throughout this study, and for the unrestricted
use of equipment. Appreciation is also extended to the
Department of Dairy Science for the use of their cryoscope. Help,
advice, and criticisms from the members of the Department of Plant
Ecology is gratefully acknowledged. Thanks and appreciation are
extended to Dr. R. T. Coupland, Head of the Department of Plant
Ecology, who provided the opportunity and initiative for this study,
and under whose helpful criticism, advice, and supervision this thesis
has been prepared.
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Degree
Doctor of Philosophy (Ph.D.)
Department
Plant Ecology
Program
Plant Ecology