Seasonal patterns of nitrogen fixation in termites

Abstract

1. Termite nitrogenase activity was highest in autumn and spring (≈ 3 μg N2 fixed termite fresh mass (g)–1 day–1) and lowest in winter and summer (≈ 0·8 μg N2 fixed termite fresh mass (g)–1 day–1). 2. The nitrogenase activity of worker termites was significantly higher than all other castes (1·58 ± 0·27 μg N2 fixed termite fresh mass (g)–1 day–1). 3. Worker termites constituted the largest proportion of all the castes throughout the study period (≈ 90%). 4. The localized input of fixed nitrogen by termites may reach 15·3 mg N log–1 day–1 and 5·6 g N log–1 year–1.

Temperate forest termites: ecology, biogeography, and ecosystem impacts

“…These rates are an order of magnitude less than non-termite-mediated nitrogen fluxes, which total between 6.5 and 26.6 kg N ha −1 year −1 in temperate forests globally (Cleveland et al, 1999). Temperate termites do, however, deposit substantial amounts of nitrogen in individual logs (Curtis & Waller, 1998), which may alter wood decomposition rates of saprotrophic fungi (Knorr et al, 2005;Boberg et al, 2008).…”

“…‡Calculated using a fresh weight of 50 mg per termite as in Fraser et al (1986). §Converted from reported C 2 H 4 production (via acetylene reduction) using the theoretical ratio of 3 : 1 as suggested in Bentley (1984) and Curtis and Waller (1998). ¶Visually estimated from Figure 1 in Curtis and Waller (1998). geographical distribution for R. flavipes.…”

“…§Converted from reported C 2 H 4 production (via acetylene reduction) using the theoretical ratio of 3 : 1 as suggested in Bentley (1984) and Curtis and Waller (1998). ¶Visually estimated from Figure 1 in Curtis and Waller (1998). geographical distribution for R. flavipes. However, our current understanding of termite-fungus interactions is limited -largely due to a lack of in situ studies -and such relationships probably depend on the specific termite, fungus, and tree species involved (e.g.…”

Insect‐mediated nitrogen dynamics in decomposing wood

“…grew on an N-free medium (Eutick et al, 1978) Heterotermes indicola (Pandey et al, 1992); workers (Curtis & Waller, 1995); workers (Curtis & Waller, 1996); workers (Curtis & Waller, 1997); workers, soldiers, presoldiers, larvae and alates (Curtis & Waller, 1998) (Prestwich & Bentley, 1981); mixed workers and soldiers (Bentley, 1984) Sylvester-Bradley et al (1983) found termites from a single nest to exhibit high rates of acetylene reduction one week but none a week later. The opposite response was observed in other nests, with a week of no detectable acetylene reduction being followed by a week of high activity.…”

“…Pandey et al (1992) Curtis and Waller (1998) estimated that the gut symbionts of Reticulitermes fix several grams of N per log per year in the south-eastern United States and suggested that it may be most ecologically relevant to view termite-infested logs as N 'hotspots', rather than thinking of inputs in terms of per unit area. The authors also suggest that the uneven input of N by termites may contribute to the nutrient patchiness of forest soils.…”