Impacts of an Invasive N2‐Fixing Tree on Hawaiian Stream Water Quality. (19th January 2013)

• Record Type: Journal Article
• Authors: Wiegner, Tracy N.; Hughes, Flint; Shizuma, Lisa M.; Bishaw, David K.; Manuel, Mark E.
• Is Part Of: Biotropica. Volume 45:Number 4(2013:Jul.)
• Page Start: 409
• Page End: 418
• Publication Date: 2013-01-19
• Subjects: Biotic communities -- Tropics -- Periodicals; Applied ecology -- Tropics -- Periodicals; Biology -- Tropics -- Periodicals; 577.80913
• DOI: 10.1111/btp.12024
• Languages: English
• ISSNs: 0006-3606

Abstract

<abstract abstract-type="main" id="btp12024-abs-0001"> <title>Abstract</title> <p>N<sub>2</sub>‐fixing trees can affect stream water quality. This has been documented in temperate streams, but not in tropical ones, even though N<sub>2</sub>‐fixing trees are prevalent in the tropics. We investigated the effects of the introduced, invasive tree, <italic>Falcataria moluccana</italic> (albizia) on water quality of Hawaiian streams. Nutrient concentrations were measured in reaches above and below <italic>F. moluccana</italic>‐dominated riparian zones of four streams over 14 mo, and benthic algal nutrient limitation was examined in one stream. NO<sub>3</sub><sup>−</sup>+NO<sub>2</sub><sup>−</sup> concentrations were up to 600 percent higher in reaches below <italic>F. moluccana</italic> stands than in ones above them. In contrast, dissolved organic nitrogen concentrations were 24 percent lower in most reaches below <italic>F. moluccana</italic> stands, and NH<sub>4</sub><sup>+</sup> and particulate nitrogen concentrations were similar above and below the stands. Dissolved organic carbon concentrations were up to 30 percent lower below <italic>F. moluccana</italic> stands, but particulate carbon concentrations were similar between reaches. Total dissolved phosphorus concentrations were similar above and below <italic>F. moluccana</italic> stands, whereas H<sub>4</sub>SiO<sub>4</sub> concentrations were higher below the stands. In the stream where benthic chlorophyll <italic>a</italic> was measured, concentrations were three times higher below the <italic>F. moluccana</italic> stand than above it. Benthic algae were co‐limited by nitrogen and phosphorus above the <italic>F. moluccana</italic> stand, and limited by phosphorus below it. These results suggest that <italic>F. moluccana</italic>'s presence relieved nitrogen‐limitation and caused the benthic algae to become solely phosphorus‐limited. Overall, our results demonstrate that <italic>F. moluccana</italic> can strongly affect the chemistry and primary producers of these tropical streams.</p> </abstract>