Seasonal Changes in Fungal Production and Biomass on Standing Dead Scirpus lacustris Litter in a Northern Prairie Wetland

Abstract

Decaying macrophytes are an important source of carbon and nutrients in fungal and bacterial communities of northern prairie wetlands. Dead macrophytes do not collapse into the water column immediately after death, and decomposition by fungi and bacteria begins while the plants are standing. The seasonal variations in fungal biomass and production on Scirpus lacustris stems, both above and below water, were measured to assess which environmental factors were dominant in affecting these variations in a typical prairie wetland. Fungal biomass and production were measured from early May to November, just prior to freeze-up. Fungal decomposition began and was greatest in the spring despite low water temperatures. The fungal production, as measured by the incorporation of [1-14 C]acetate into ergosterol, ranged from 1.8 to 376 g of C g of ash-free dry mass (AFDM) ؊1 day ؊1 , and the biomass, as estimated by using ergosterol, ranged from nondetectable to 5.8 mg of C g of AFDM ؊1 . There was no significant difference in biomass or production between aerial and submerged portions of Scirpus stems. The water temperature was correlated with fungal production (r ‫؍‬ 0.7, P < 0.005) for aerial stem pieces but not for submerged pieces. However, in laboratory experiments water temperature had a measurable effect on both biomass and production in submerged stem pieces. Changes in fungal biomass and productivity on freshly cut green Scirpus stems decaying in the water either exposed to natural solar radiation or protected from UV radiation were monitored over the summer. There was no significant difference in either fungal biomass (P ‫؍‬ 0.76) or production (P ‫؍‬ 0.96) between the two light treatments. The fungal biomass and rates of production were within the lower range of the values reported elsewhere, probably as a result of the colder climate and perhaps the lower lability of Scirpus stems compared to the labilities of the leaves and different macrophytes examined in other studies performed at lower latitudes.

Contributions of fungi to carbon flow and nutrient cycling from standing dead Typha angustifolia leaf litter in a temperate freshwater marsh

“…Despite abundant evidence of standing litter accumulation in freshwater marsh habitats and extensive fungal colonization, few studies have quantified rates of carbon flow into fungi during standing litter decomposition (Newell et al 1995;Findlay et al 2002;Verma et al 2003) or assessed their potential contribution to plant litter carbon and nutrient transformations (Gessner et al 2007). As a result, fungal decay processes within standing litter compartments of freshwater marshes have not been recognized as a potential pathway in wetland biogeochemical cycles (Mitsch and Gosselink 2007).…”

Kinetic pathways for the anaerobic decomposition of Ludwigia inclinata

“…Both studies reported the temperature as the most important environmental factor for the cellulose decay. Additionally, Verma et al (2003) reported the direct proportionality between the temperature and the development of aquatic fungal populations, suggesting the temperature as the key factor to seasonal changes in fungal growth and activity.…”

effect of tetracycline on the colonization and growth of microbes on Scirpus lacustris litter in oligotrophic and eutrophic waters

“…The S. la- custris we used was from the previous year's stand and was standing dead on the periphery of Pond 50 when harvested. This means that from the time they died to when we harvested them they were exposed to the environment and, under favorable conditions, would have been colonized and decomposed by microbes (Verma et al 2003). The decomposition would not have occurred homogeneously over the entire surface of the stem, but rather in patches, resulting in a patchwork pattern with some parts of the stem decomposed while other parts would have remained intact.…”

“…Aquatic litter decomposition is dominated by fungi, accounting for 63 to 99% of the total microbial biomass and production (Gessner & Newell 2002, Hieber & Gessner 2002, Verma et al 2003. The variability in fungal dominance may be due to the nature and carbon content of the plant substrate (Gessner et al 1993, Baldy et al 1995, Gulis 2001, Mille-Lindblom et al 2006b), the nature of the aquatic system or because of bacterial competition and inhibition (Moller et al 1999, Gulis & Suberkropp 2003.…”

“…Fungal biomass and production have been estimated by counting conidia, measuring fungal hyphae, plating on nutrient media and by using ergosterol to estimate eumycotic biomass. Instantaneous rates of fungal production have been measured by using the [1-14 C] acetate incorporation into ergosterol method (Newell 1996, Gessner & Newell 2002, Verma et al 2003. Each of these methods has its limitations.…”