Abstract. Ecosystem management is management driven by explicit goals, executed by policies, protocols, and practices, and made adaptable by monitoring and research based on our best understanding of the ecological interactions and processes necessary to sustain ecosystem composition, structure, and function.In recent years, sustainability has become an explicitly stated, even legislatively mandated, goal of natural resource management agencies. In practice, however, management approaches have often focused on maximizing short-term yield and economic gain rather than long-term sustainability. Several obstacles contribute to this disparity, including: ( 1) inadequate information on the biological diversity of environments; (2) widespread ignorance of the function and dynamics of ecosystems; (3) the openness and interconnectedness of ecosystems on scales that transcend management boundaries; (4) a prevailing public perception that the immediate economic and social value of supposedly renewable resources outweighs the risk of future ecosystem damage or the benefits of alternative management approaches. The goal of ecosystem management is to overcome these obstacles.Ecosystem management includes the following elements: (1) Sustainability. Ecosystem management does not focus primarily on "deliverables" but rather regards intergenerational sustainability as a precondition. (2) Vol. 6, No.3 goals that specify future processes and outcomes necessary for sustainability. (3) Sound ecological models and understanding. Ecosystem management relies on research performed at all levels of ecological organization. (4) Complexity and connectedness. Ecosystem management recognizes that biological diversity and structural complexity strengthen ecosystems against disturbance and supply the genetic resources necessary to adapt to long-term change.(5) The dynamic character of ecosystems. Recognizing that change and evolution are inherent in ecosystem sustainability, ecosystem management avoids attempts to "freeze" ecosystems in a particular state or configuration. (6) Context and scale. Ecosystem processes operate over a wide range of spatial and temporal scales, and their behavior at any given location is greatly affected by surrounding systems. Thus, there is no single appropriate scale or time frame for management. (7) Humans as ecosystem components. Ecosystem management values the active role of humans in achieving sustainable management goals. (8) Adaptability and accountability. Ecosystem management acknowledges that current knowledge and paradigms of ecosystem function are provisional, incomplete, and subject to change. Management approaches must be viewed as hypotheses to be tested by research and monitoring programs.The following are fundamental scientific precepts for ecosystem management.(1) Spatial and temporal scale are critical. Ecosystem function includes inputs, outputs, cycling of materials and energy, and the interactions of organisms. Boundaries defined for the study or management of one process are often inapp...

Fire strongly influences carbon cycling and storage in boreal forests. In the near‐term, if global warming occurs, the frequency and intensity of fires in boreal forests are likely to increase significantly. A sensitivity analysis on the relationship between fire and carbon storage in the living‐biomass and ground‐layer compartments of boreal forests was performed to determine how the carbon stocks would be expected to change as a result of global warming. A model was developed to study this sensitivity. The model shows if the annual area burned in boreal forests increases by 50%, as predicted by some studies, then the amount of carbon stored in the ground layer would decrease between 3.5 and 5.6 kg/m2, and the amount of carbon stored in the living biomass would increase by 1.2 kg/m2. There would be a net loss of carbon in boreal forests between 2.3 and 4.4 kg/m2, or 27.1‐51.9 Pg on a global scale. Because the carbon in the ground layer is lost more quickly than carbon is accumulated in living biomass, this could lead to a short‐term release of carbon over the next 50‐100 yr at a rate of 0.33‐0.8 Pg/yr, dependent on the distribution of carbon between organic and mineral soil in the ground layer (which is presently not well‐understood) and the increase in fire frequency caused by global warming.

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In the first few years following fire, burned chaparral areas are typified by a flush of seed germination and seedling growth not seen in unburned chaparral. The effects of fire on factors of potential importance to this plant response were examined in recently burned and long unburned chaparral, dominated by Adenostoma fasciculatum, in the Santa Ynez Mountains near Santa Barbara, California. Measurement of soil moisture, soil texture, and light indicated that changes in these factors following fire had little direct effect on postfire germination and growth. Bacteria and fungi were more abundant in burned than in unburned chaparral soil. Thus, the hypothesis that microbial depletion of soil oxygen in unburned chaparral inhibits seed germination appears untenable. Changes in organic matter content, pH, nitrogen, phosphorus, sulfur, potassium, calcium, and magnesium were examined in the upper soil layers of both burned and unburned chaparral during the first 18 mo following fire. Mineral addition as ash—fall was also evaluated. Burning increased levels of most mineral elements significantly. Furthermore, a large reservoir of readily available organic nutrients was added in the ash. Causes of low nutrient levels in unburned chaparral were also investigated. Additions of nutrients to unburned chaparral soil in the greenhouse and field resulted in increased growth of species common in burned chaparral areas. Bioassays of aqueous A. fasciculatum leaf washings were performed against 10 plant species common in burned chaparral areas. Significant depression of germination and growth was observed. Rain throughfall collected under the shrubs was also inhibitory. Efforts to isolate and identify the toxins are described. Numbers of small herbivorous mammals were greatly reduced in recently burned chaparral. This factor is shown to have a marked effect on seedling survival. Applications of various heat treatments to unburned chaparral soil and to fresh seeds of species common to burned chaparral indicated that the seed of several species are released from dormancy by heat. Insolational heating of soil in cleared, but unburned, chaparral is sufficient to stimulate germination.