Macrophytes

Estimates of the contribution of macrophyte production to organic matter budgets are too few

FIGURE 12.2 Daily rates of gross primary production (GPP: positive values, black line) and ecosystem respiration (R: negative values, gray line) measured in Walker Branch from 28 January 2004 through 31 January 2006. Vertical lines separate years. Arrows indicate storms during which maximum instantaneous discharge was greater than or equal to 100 L s1. Variance in GPP correlates with seasonal and day-to-day variation in light levels. Variance in ecosystem R correlates with seasonal and day-to-day variation in GPP and autumn leaf inputs. (Reproduced from Roberts et al. 2007.)

FIGURE 12.2 Daily rates of gross primary production (GPP: positive values, black line) and ecosystem respiration (R: negative values, gray line) measured in Walker Branch from 28 January 2004 through 31 January 2006. Vertical lines separate years. Arrows indicate storms during which maximum instantaneous discharge was greater than or equal to 100 L s1. Variance in GPP correlates with seasonal and day-to-day variation in light levels. Variance in ecosystem R correlates with seasonal and day-to-day variation in GPP and autumn leaf inputs. (Reproduced from Roberts et al. 2007.)

to generalize, but at least in some circumstances they are a significant component of system primary production. In the New River, Virginia, production by Podostemum ceratophyllum was about equivalent to periphyton production in contribution to the annual organic matter budget (Hill and Webster 1982a, 1983). Macro-phytes contributed about 9% of the annual primary production in the Fort River, Massachusetts (Fisher and Carpenter 1976), and about 15% in the Red River, Michigan (King and Ball 1966).

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