Plant Connections Leader's Guide—Lesson 3: What Makes Plants Grow?1
The vital needs of a plant are very much like our own—light, water, air, nutrients, and a proper temperature. The relative importance of each of these needs differs widely among plants. The ability of a plant species to spread throughout a geographic area is a direct result of its adaption to the abiotic and biotic components of the area. Although most habitat components act on a plant simultaneously and should be considered together, the lack of one essential component can determine the health of a plant. This factor, whatever it may be, is referred to as a limiting factor. The concept of limiting factors applies to all aspects of a plant's interaction with its habitat. Any factor in the ecosystem can act as a limiting factor. For example, water is important to many species; most species cannot live in desert regions because of lack of water and most cannot live in marshes because of excess water. Extreme temperatures inhibit plant growth in many regions; lack of warmth in winter is a limiting factor that keeps many species restricted to the tropics.
Another limiting factor is often competition from species that use the same resources. Competition is the principal interaction among plants. Plants of the same species are strongly competitive because they have the same requirements for sunlight, water, and nutrients.
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