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everywhere |
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Climate Matters |
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Light and Diversity |
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Serengeti National Park, Tanzania |
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A forest stand in the Cedar River Watershed which was logged and burned in the 1920s. Little light penetrates the forest canopy, and the understory features few vascular plant species. Shrubs and sub-canopy trees are mostly absent.
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An old growth stand, adjacent to the logged stand (photo above), exhibits a much higher level of structural and species diversity. The canopy is high and open, and the forest floor features many species of forbs. Shrubs grow vigorously, and sub-canopy trees are present. |
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What determines the plant diversity in a forest? Forests of varying ages (time since disturbance) are observed to have very different structure and species composition. Generally, old-growth forests have more plant species (and attendant animal species), but old-growth forests are very uncommon west of the Pacific crest. Would it be possible to manipulate younger forests to achieve species diversity closer to that observed in old forests?
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However, young forests are not uniformly devoid of understory species. Patches within the forest may have thriving populations. Perhaps these patches are controlled by the structure of the overstory. Or they could be related to soil and water conditions. |
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Here the forest floor is dominated by mosses. There is one vascular plant species in this frame. |
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Not too far away in the same forest is a rich understory. There are fifteen vascular plant species in this frame, which is considerably smaller than the photo above. Neither area contains shrub species. |