UBC Theses and Dissertations

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UBC Theses and Dissertations

Phytogeocoenoses of a coastal lowland ecosystem, Devon island, N.W.T. Revel, Richard David


Little synecological work has been conducted in the Sub-boreal Spruce Biogeoclimatic Zone of north-central British Columbia. This thesis is a vegetation and environment study of the previously mentioned zone based on the concept of biogeoclimatology developed by Krajina and his students. Methods of vegetation description follow standard phytosociological techniques. The aims of the study were: 1) to describe quantitatively and qualitatively the vegetation of the Sub-boreal Spruce Biogeoclimatic Zone using the methods followed by the Zurich-Montpellier school of phytosociology as modified by Krajina, 2) to collect similar data on environmental parameters from the individual plots, 3) using the above data, and in addition the environmental data collected by the co-worker Wali, to develop a meaningful and recognizable classification scheme of the Sub-boreal Spruce Zone ecosystems, 4) to develop an integrated hierarchal scheme for the proposed vegetation units following standard phytosociological procedures, and 5) to collect detailed information on the nature and function of the tree species in the proposed ecosystem units. A total of 145 sample plots were established in the different phytogeocoenoses and detailed vegetation studies carried out on each. These plots were later grouped into plant associations based on their floristic and environmental similarity. The plant associations were then grouped into the higher units of alliances and orders. A total of forty-six synsystematic units are described for the study area. The break-down of these is as follows: seven orders, thirteen alliances, eighteen plant associations, two sub-associations, and six variations. In order to obtain detailed information on the growth and structure of the different tree species in the forested plant associations, each tree falling within the study plot was measured for both diameter (DBH) and height and a representative number of trees were bored and increment cores extracted to facilitate the calculation of the growth rate of the trees. Using the above information, diameter/ height graphs were developed for each species in each of the plant associations. Other treatments of this data include calculations of tree volumes, basal areas, minimum, maximum, and average height and diameter of each tree species in each plant association, number of stems per acre, and site index. General information describing the plot is also included. This information is as follows: elevation, locality, data of analysis, land form, relief shape, exposure, slope gradient, erosion, drainage, hygrotope, trophotope and the type of parent material. This information is presented for each of the plant associations. One soil pit was dug in each of the sample plots and soil samples collected from each of the diagnostic horizons in the pit. These samples were subjected to physical and chemical analyses. The analyses included: soil texture, cation exchange capacity, exchangeable cations (Na, K, Ca, and Mg), total nitrogen, carbon content, organic matter content, available phosphorus, sulphur, and pH. In conclusion it becomes apparent that the methods and findings of this thesis will have strong applications to future land management in the Sub-boreal Spruce Biogeo-climatic Zone.

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