The Effects of Fire on Photosynthesis in Chaparral Resprouts
The success and rapid growth of vegetation regenerating after fire is probably due to a complex set of factors. In sprouting shrubs it may be due to the utilization of carbohydrate reserves in the roots and lignotubers. It may also be due in part to increased photosynthetic rates, as Radosevich et al. (1977) have reported for resprouting Adenostoma fasciculatum. Christensen and Muller (1975) point out the enhancing effects of improved nutrient status of the chaparral on growth following fire. Photosynthesis and the rate of regrowth could also be increased due to improved water relations of resprouts. A reduction in the leaf area index after top removal would decrease the total transpirational surfaces and presumably decrease water loss. Greater tissue water potentials following fire may result in lowered stomatal resistance to water vapour and carbon dioxide flux. Christensen and Muller (1975) reported increased soil nutrients in chaparral areas after a fire. Higher nutrient levels may result in greater enzyme concentrations, higher respiration rates and greater photosynthetic rates. Numerous studies have shown the positive correlation between nitrogen availability and photosynthetic rate (Longstreth and Nobel 1980) and between leaf nitrogen and photosynthetic performance (Natr 1970). Most essential nutrients, including nitrogen, phosphorus, potassium, magnesium, sulphur, calcium, iron, manganese, copper, boron, zinc and molybdenum, in deficient amounts may limit photosynthesis (Bottrill et al. 1970; Longstreth and Nobel 1980; Spiller and Terry 1980; Terry 1980).
KeywordsBiomass Zinc Burning Permeability Phosphorus
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