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Fire: Not Always Bad, Not Always Good


MACK NASH, GARDENS SUPERVISOR


Fire ecology examines the impact of fi re on the processes of how organisms function in their environments. Just as other natural disturbances such as fl oods, drought, and severe storms shape our ecosystems, so does fi re. Fire is an ancient natural component of many ecosystems which has a recurrent or cyclic nature that actually keeps these ecosystems healthy and species diverse. Plants that live in fi re-prone ecosystems employ various methods of coping with fi re. Some species tolerate it and others embrace it as a necessary part of their life cycles.


Understanding how fi re aff ects our environment and


why fi res today behave the way they do requires some understanding of how fi re has been treated and used by man historically. In North America, prior to European settlement, there is evidence Native Americans used fi re to shape their environment. In fact, fi res may have been set quite frequently to make the land more suitable for a nomadic, hunting and gathering lifestyle. But as settlements began to develop, fi res were suppressed to avoid destruction of property. T e issue of burgeoning human development into fi re-prone areas is at the heart of fi re management and habitat conservation today because the urban-wildland interface is constantly expanding and more and more habitat is being lost as natural lands are further dissected creating patches rather than vast, continuous expanses of habitat.


6 www.LivingDesert.org


Due to years of fi re suppression, over-accumulated fuel loads exist in many natural lands. T is poses a threat to those ecosystems and human safety as well. Fires in fi re-suppressed lands with over-accumulated fuel loads often result in high- intensity fi res that can transform into large scale disasters and have the capacity to damage ecosystems.


Fire aff ects all parts of an ecosystem from the soil and the smallest organisms to the largest. Fire recycles nutrients bound in organic matter back to the soil. T e resulting increase in soil nutrients has a mild fertilization eff ect and often prepares the soil for seed germination and new plant growth. T e removal of leaf litter and other organic matter from the soil surface can lead to erosion, especially on mountains and slopes. Yet some plant species require bare soil or mineral soil for their seeds to germinate. Fire also aff ects soil temperature by increasing the amount of sunlight that reaches the soil. T e increase in soil nutrients and soil temperature after a fi re often aids the regeneration events that follow a fi re.


Because the soil provides insulation against the heat of


the fi re, soil organisms are not extensively killed unless the fi re is very severe. Even then soil fungi have been shown to regenerate rapidly after a fi re. Some research indicates that the increase in nutrients and temperature may speed the recovery of soil organisms.


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