<b>Decomposition and release dynamics of nitrogen and phosphorous from vegetal fractions of <em>Salvinia auriculata</em> Aubl. in a Legal Amazon reservoir</b> - doi: 10.4025/actascibiolsci.v33i1.5630

Abstract

This study aimed to determine the decomposition coefficients of the submerged (SP) and aerial part (AP) of S. auriculata at two different depths within water column (surface and sediment). It also quantified the decomposition yield of S. auriculata and the temporal changes of nitrogen and phosphorous content of the remaining biomass. The macrophytes were fractionated in parts and were dried in sequence until attaining constant weight. The litterbags with plant material were incubated in the reservoir of UHE Lajeado. The results of mass loss showed that there were no significant differences among the AP-sed and AP-sur (p > 0.05). However, the AP-sed was significantly different from SP-sed (p < 0.05) and SP-sur (p < 0.01). The AP-sed presented a decay coefficient (k) of 0.0102 day^-1 and AP-sur a k of 0.0067 day^-1. The SP-sed presented a k of 0.0027 day^-1 and the SP-sur 0.0040 day^-1. It was also noticed that during the first days of decomposition great amounts of nitrogen and phosphorous were solubilized. This event was related to the leachate process; from the 14th day of decomposition, an increasing trend was observed in nitrogen concentrations. This fact was probably related to detritus enrichment by microbial colonization.