Composition and deposition of throughfall in a flooded forest archipelago (Negro River, Brazil)

    loading  Checking for direct PDF access through Ovid


The sources of spatial and temporal variation and rates of nutrient deposition via throughfall were studied for 9 months in the Anavilhanas archipelago of the Negro River, Brazil. A total of 30 events was sampled individually for rain and throughfall chemistry in a 1-ha plot of flooded forest. Throughfall samples were collected in 40 collectors distributed in five parallel transects in the study plot, while rain was collected in 4 collectors in an adjacent channel. Volume-weighted mean (VWM) concentrations of solutes in rain were consistently lower than in throughfall, except for H+, NO−3 and NH+4. Ratios of VWM concentrations of rain to throughfall indicated that K+, followed by Mg2+ and PO3−4, were the most enhanced solutes as rain passed through the forest canopy. The deposition of solutes varied significantly among transects, except for Na+ and Ca2+, and was significantly correlated with maximum flooding depth, foliar nutrient content soil fertility and canopy closure for most solutes. The concentrations of PO3−4 and most major ions were higher in throughfall compared to those in rain due to canopy exchange and dry deposition. In contrast, NO−3, NH+4 and H+ were retained due to immobilization by leafy canopy and ion exchange processes. Solute inputs via throughfall (not including stemflow) to a floodplain lake (Lake Prato) of the archipelago accounted for 30 to 64% of the total for most solutes in the lake at high water, which indicates that throughfall is an important source of nutrients to the aquatic ecosystem of the Anavilhanas archipelago.

Related Topics

    loading  Loading Related Articles