Aerial and detritus production of the cordgrass Spartina densiflora in a Southwestern Atlantic salt marsh.

VERA, F.; GUTIÉRREZ, J. L.; RIBEIRO, P. D.

CANADIAN JOURNAL OF BOTANY

NRC Research Press

Año: 2009 vol. 87 p. 482 - 491

0008-4026

We used a nondestructive method to estimate aerial and detritus productivity of the cordgrass Spartina densifloraBrongn. and evaluated the relative contribution of newly emerged and preexisting tillers to net aerial biomass and detritusproduction, the relative contribution of tiller detachment and leaf shedding to detritus production, and the incidenceof crab (Neohelice (Chasmagnathus) granulata (Dana, 1851)), herbivory in relation to tiller age and its implications fortiller survival. Estimates of aerial and detritus productivity varied between 706.72 (SD = 153.38) and 786.15 (SD =162.75) gm–2year–1 and between 1054.23 (SD = 224.49) and 1223.17 (SD = 246.84) gm–2year–1, respectively. These estimatesof aerial production are far below the higher productivity estimates known for species of the genus Spartina butwithin the range of values obtained with nondestructive methods (i.e., 300–1500 gm–2year–1). Detachment of standingdeadtillers and leaf shedding contributed virtually in equal quantities to detritus production (i.e., 52% and 48% of the totaldetritus biomass, respectively). On the other hand, net aerial biomass production was highly dependent on tiller recruitment,with 67% of total biomass production contributed by the growth of tillers that emerged during the course of thestudy. However, crabs seem to graze on tillers irrespective of their age. Such nonselective crab grazing on tillers of differentage together with the long tiller survival after crab grazing (often more than a year) suggests that crabs do not ostensiblyaffect S. densiflora production.