Productivity and Decomposition of the Dominant Salt Marsh Plants in Louisiana
1978
White, David A. | Weiss, T Edward | Trapani, John M. | Thien, Leonard B.
Net primary production and decomposition of the 4 dominant salt marsh plants found in Louisiana were determined. Live and dead standing crops were calculated by the harvest method over an annual cycle. Litterbags were used to estimate loss rates of vegetation from the marsh. Peak standing crops were: 1164 g/m² for Distichlis spicata, 2194 g/m² for Spartina patens, 1959 g/m² for Juncus roemerianus and 1473 g/m² for Spartina alterniflora. Net production estimates using the Smalley (1958) method were from 1291 g.m⁽—2). yr⁽—1) for D. spicata, 1342 g.m⁽—2).yr⁽—1) for S. patens. 1740 g.m⁽—2).yr⁽—1) for J. roemerianus and 1527 g.m⁽—2).yr⁽—1) for S. alterniflora. Using the Wiegert and Evans' (1964) method net production for the 4 species was: 1162 g.m⁽—2).yr⁽—1), D. spicata; 1428 g.m⁽—2).yr⁽—1), S. patens; 1806 g.m⁽—2).yr⁽—1), J. roemerianus and 2895 g.m⁽—2)°yr⁽—1) for S. alterniflora. It is estimated that these 4 species of Louisiana marshland plants produce 146 x 10⁵ metric tons/yr of plant material. This accounts for approximately one—half of 17,050 km² of marshes in the state. In general production was higher for this Louisiana marsh than reported in Atlantic Coast marshes. Also, decomposition rates were considerably higher. Spartina alterniflora decomposed most rapidal with 100% removal in 7 mo; 24%/yr for D. spicata, 36%/yr for S. patens and 20%/yr for J. roemerianus. In additional a belowrgound standing crop analysis was undertaken on new S. alterniflora roots.
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