UBC Theses and Dissertations
Order and organization in lodgepole pine forests of West-Central British Columbia Brulisauer, Alfred Robert
Trends of temporal development were documented for lodgepole pine-dominated forest communities recovering after fire disturbance in the interior of British Columbia. Order and organization within these communities, considered to be key indicators of the recovery process, were quantified by means of equal frequency ellipses in multivariate space and angular comparisons between eigenvectors. Estimates of ecological order were also based on more traditional methods such as Shannon diversity and spatial heterogeneity. Observed trends were evaluated in light of recent attempts to interpret development in the living world as resulting from energetic dynamics in non-equilibrium systems. Of particular interest were phenomenological similarities between successional and organismic development as predicted from an interpretation of succession as a developmental process. In addition, implications of the results to questions of diversity and stability and their mutual relationship in ecological systems were also explored. Similarities were evaluated between successional and organismic development according to four phenomenological rules (Weber et al. 1989, Salthe 1991) . Succession in the investigated communities appeared to follow similar trends as found in organismic development in terms of energetic efficiency, structural complexity, speed and course of development and system stability. The undivided data (xeric and mesic stands combined) suggested a steady decrease in diversity up to a penultimate phase with a subsequent increase as climax was approached. Eccentricity of the equal frequency ellipses, interpreted to be an indicator of redundant system configurations, followed a similar pattern, thereby behaving in agreement with expectations from Prigogine’s minimum dissipation principle predicting a system to sacrifice multiple pathways in exchange for higher energetic efficiency. Order, quantified based on species data, was found to remain relatively stable during succession. Organizational dynamics were most pronounced at the onset of succession and slowed down with increasing stand age. Stability and resilience were found to be lower on sites of poor environmental conditions than on mesic sites. No relationship, however, of stability or resilience with diversity could be established as levels of diversity in both mesic and xeric sites were similar. Lower redundancy on xeric sites was interpreted as an indicator for lower stability, leading to higher sensitivity to environmental fluctuations during the process of recovery. It was found that processes in successional and organismic development were reasonably similar except for sites in unproductive locations. This was interpreted to be a result of the lower degree of integration of such sites. Thus, the investigated communities appeared to exhibit patterns similar to organismic development if autogenic processes were able to proceed relatively undisturbed.
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