A comparison of phosphorus and DOC leachates from different types of leaf litter in an urban environment

Abstract

1. The leaching rates of filterable reactive phosphorus (FRP) and dissolved organic carbon (DOC) from five leaf litter types commonly occurring in urban environments in Mediterranean regions of Southern Australia were compared. The relative composition, bioavailability and oxygen demand of this DOC were also assessed. Four tree species were assessed, including the native river red gum (Eucalyptus camaldulensis) and three introduced deciduous species, the English elm (Ulmus procera), London plane (Platanus acerifolia) and white poplar (Populus alba). Grass cuttings (mixed species) were selected as a common garden waste. 2. Except for English elm, the majority of FRP and DOC was released within the first 48 h. Grass cuttings released the highest amount of FRP with white poplar releasing the most DOC. Species that released relatively high amounts of DOC (white poplar, English elm, river red gum) released relatively low amounts of FRP. Conversely, species that released relatively low amounts of DOC (grass cuttings and London plane) tended to release relatively high amounts of FRP. 3. Analysis of DOC composition, combined with the differing oxygen demand and DOC depletion curves, demonstrated that there were substantial differences in the DOC leached from the leaf litter of the different species. Biochemical oxygen demand and the biodegradability of the DOC was positively correlated with the proportion of hydrophilic and hydrophobic acids present in the leachate. 4. These results demonstrate that simple measurements of nutrient release per gram of leaf litter would be insufficient to predict the ecological impact on receiving waters resulting from changes in dominant vegetation. Furthermore, the use of traps to prevent particulate leaf material from entering streams may have limited potential for reducing the load of dissolved nutrients. We conclude that any changes to vegetation type which substantially alter the timing of leaf fall or the composition of leaf leachates should be avoided.

Decomposition of tree leaf litter on pavement: implications for urban water quality

“…Furthermore, any litter washing down storm drains into catch basins or infiltration trenches will become submerged in water, similar to our leaching experiments. Our results show that litter can release substantial amounts of dissolved P in these conditions, which would then pass through stormwater infrastructure that is designed to settle out or trap particulate P (Wallace et al 2008). Additional research is needed to determine decomposition rates for leaf litter trapped in stormwater catch basins and ponds.…”

Dissolved and particulate organic carbon fluxes from an agricultural watershed during consecutive tropical storms

“…Despite the paramount importance of organic carbon molecules to terrestrial, marine, and global biogeochemical processes, carbon export from watersheds remains poorly described. Terrestrial organic carbon export is controlled by soil and vegetation type [Dittmar et al, 2006;Wickland et al, 2007;Wallace et al, 2008], microbial community composition [Cragg and Bardgett, 2001], and water residence times and hydrologic flow paths [McDowell and Likens, 1988;Dalzell et al, 2005]. All of these factors are ultimately controlled by land use, topography, and climate.…”

Subsidy quantity and recipient community structure mediate plankton responses to autumn leaf drop

“…Although trees resorb nutrients from leaves prior to abscission (Chapin et al 2002), freshly fallen leaves typically contain high concentrations of nitrogen (N) (Goldman 1961, Richey andWissmar 1979) and phosphorus (P) (Cowen and Lee 1973, Pieczynska 1986, France et al 1996, Wallace et al 2008, France 2011 relative to their availability in freshwater ecosystems. Because both N and P are released relatively quickly upon contact with water (Chapin et al 2002), leaf leachates have the potential to strongly stimulate phytoplankton in the weeks following leaf abscission, so long as there is v www.esajournals.org sufficient light for photosynthesis (Fig.…”