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  • Library: Creating a new vision for BC forests

    Raven Tree
    By Suzanne W. Simard, David A. Perry, Melanie D. Jones, David D. Myrold, Daniel M. Durall & Randy Molinak

    Abstract: Different plant species can be compatible with the same species of mycorrhizal fungi1,2 and be connected to one another by a common mycelium. Transfer of carbon, nitrogen and phosphorus through interconnecting mycelia has been measured frequently in laboratory experiments, but it is not known whether transfer is bidirectional, whether there is a net gain by one plant over its connected partner, or whether transfer affects plant performance in the field. Laboratory studies using isotope tracers show that the magnitude of one-way transfer can be influenced by shading of ‘receiver’ plants, fertilization of ‘donor’ plants with phosphorus, or use of nitrogen-fixing donor plants and non-nitrogen-fixing receiver plants, indicating that movement may be governed by source–sink relationships. Here we use reciprocal isotope labelling in the field to demonstrate bidirectional carbon transfer between the ectomycorrhizal tree species Betula papyrifera and Pseudotsuga menziesii, resulting in net carbon gain by P. menziesii. Thuja plicata seedlings lacking ectomycorrhizae absorb small amounts of isotope, suggesting that carbon transfer between B. papyrifera and P. menziesii is primarily through the direct hyphal pathway. Net gain by P. menziesii seedlings represents on average 6 percent of carbon isotope uptake through photosynthesis. The magnitude of net transfer is influenced by shading of P. menziesii, indicating that source–sink relationships regulate such carbon transfer under field conditions.
    Net transfer of carbon between ectomycorrhizal tree species in the field: Net transfer of carbon between ectomycorrhizal tree species in the field.pdf
    Raven Tree
    By C.S. Holling and Gary Meffe

    Abstract: As the human population grows and natural resources decline, there is pressure to apply increasing levels of top-down, command-and-control management to natural resources. This is manifested in attempts to control ecosystems and in socioeconomic institutions that respond to erratic or surprising ecosystem behaviour with more control. Command and control, however, usually results in unforeseen consequences for both natural ecosystems and human welfare in the form of collapsing resources, social and economic strife, and losses of biological diversity. We describe the "pathology of natural resource management," defined as a loss of system resilience when the range of natural variation in the system is reduced encapsulates the unsustainable environmental, social, and economic outcomes of command-and-control resource management. If natural levels of variation in system behaviour are reduced through command-and-control, then the system becomes less resilient to external perturbations, resulting in crises and surprises. We provide several examples of this pathology in management. An ultimate pathology emerges when resource management agencies, through initial success with command and control, lose sight of their original purposes, eliminate research and monitoring, and focus on efficiency of control. They then become isolated from the managed systems and inflexible in structure. Simultaneously, through overcapitalization, society becomes dependent upon command and control, demands it in greater intensity, and ignores the underlying ecological change or collapse that is developing. Solutions to this pathology cannot come from further command and control (regulations) but must come from innovative approaches involving incentives leading to more resilient ecosystems, more flexible agencies, more self-reliant industries, and a more knowledgeable citizenry. We discuss several aspects of ecosystem pattern and dynamics at large scales that provide insight into ecosystem resilience, and we propose a "Golden Rule" of natural resource management that we believe is necessary for sustainability: management should strive to retain critical types and ranges of natural variation in resource systems in order to maintain their resiliency.
    Command and Control and the Pathology of Natural Resource Management (1996): 
    Command and Control and the Pathology of Natural Resource Management Hollings & Meffe 1996 (optimized).pdf
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