Ecology by Eugene Odum

Author:Eugene Odum [Odum, Eugene]
Language: eng
Format: epub
Publisher: [New York, Holt, Rinehart and Winston]
Published: 1963-05-14T23:00:00+00:00

LIMITING FACTORS— LIEBIGS LAW EXTENDED

species at the expense of others. Many natural communities in such region s are "fir e types^ Jn_ thnf th/> ir p^peri't v or verv survival depends on fire. The effect of fire in one such community is shown in the sketches in Fig. 5-5. In this case the grass is not only adapted to fire but is much more valuable to man than the desert shrubs that tend to increase in the absence of fire. If man wants to keep fire out of such communities he must substitute something else in order to prevent a change to an economically less desirable vegetation. Chemicals may be effective, but they are much more expensive than "controlled" or "prescribed" burning as practiced, for example, in southeastern long-leafed pine forests, another fire-type ecosystem.

Although more work needs to be done in this area, it now appears that in dry or hot regions fire acts as a decomposer to bring about a release of mineral nutrients from accumulated old litter that becomes so dry that bacteria and fungi cannot act on it. Thus, fire may actually increase productivity by speeding up recycling. Certainly the big game herds of Africa or the deer in California chaparral (a shrub fire type) do not thrive unless periodic fires bring on a flush of new palatable grass or foliage. Fu rthermore, perio dic light fires prevent the start of bad fires by keeping the combusti ble surfa ce titter to a minimum. In southern California, f or example, fare prevention in tKe chaparrarv egetation has often resulted in severe fares that wipe out many homes.

Ttls extremely important that we distinguish between the light surface fires characteristic of the fire-tvpe ecosystem and the wild forest fires of northern forests; the latter, of course, are all bad, since they destroy nearly the

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.