There are various major types of vegetation where there is evidence that fire has played a great role in their formation. This applies, to some savannas, mid-latitude grassland.
Fire may assist in seed germination. Fire alters seedbeds. If litter and humus removal are substantial, large areas of this ash, bare soil or thin humus may be created. Besides, fires can control forest insects, parasites and fungi-a process termed “sanitization”. It also seems to stimulate the flowering and fruiting of many shrubs and herbs. Minerals are released both as ash and through increased decomposition rates of organic layers.
Planned fire destroys certain vegetations but saves the fire resistant plant, e.g the leguminous plant. The nitrogen-fixing bacteria in it will quickly colonize the burned area and the bacterial decomposition of dead plant bodies makes the area fertile.
The sweet pea belongs to an order of plants known as Fabales, also known as legumes. The legumes are an economically important group of plants that have root nodules containing a bacterium that helps return nitrogen to the soil. Because of this characteristic, legumes such as the sweet pea, are used to enrich nitrogen-poor soils. Other legumes include beans, peanuts, soybeans, and alfalfa.