Synthesis of ecosystem consequences of the natural patterns of biodiversity

When coupled with the large-scale biogeographic patterns of fire regimes and maritime vs. continental climate patterns, the high functional diversity of boreal plants and animals may result in diverse patterns of ecosystem assembly (Figures 3.1 and 3.2) and complex temporal behaviors, such as oscillations and even chaos of productivity (Cohen and Pastor 1995). Ecosystems appear to be more diverse and complex in continental regions without permafrost, where droughts are common and fire-cycles are several decades to at most 150 years (Heinselman 1981; Yarie 1981; Payette 1992). After a fire, two successional pathways are possible (Figure 3.2). One leads to serotinous conifers such as Pin us banksiana and Picea mariana. The high res'in and lignin con tent of the litter from these slow-growing species promotes low nutrient availability as well as high fuel flammability; these lead to positive feedbacks to maintain stands dominated by such conifers (Heinselman 1981; Flanagan and Van CJeve 1983; Pastor and Mladetioff 1992; Pastor 1993). The other successional pathway leads to shade-intol-

Birds

insects

High Diversity

Predators

Nutrient Availabilty f-

Lignin Resin t*

_ Mammalian r> Herbivores

Nutrient Availabilty

Lignin. Defense -1 Compounds -I

t"

Early Succession - Hardwoods *

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