Disturbance And The Resilience Of Coupled Carbon And Nitrogen Cycling In A North Temperate Forest

  • Sites: US-UMd
  • Publication Type: JOUR
  • Authors: Nave, L.E.; Gough, C.M.; Maurer, K.D.; Bohrer, G; Hardiman, B.S.; Le Moine, J.; Munoz, A.B.; Nadelhoffer, K.J.; Sparks, J.P.; Strahm, B.D.; Vogel, C.S.; Curtis, P.S.

  • Much of our biogeochemical understanding of forest disturbances comes from studies of severe or stand-replacing events, which may have different impacts on coupled carbon (C) and nitrogen (N) cycling than subtler disturbances affecting only a fraction of the canopy. We measured a suite of interdependent C and N cycling processes following an experimental disturbance that accelerated mortality of the early successional canopy dominants (39% of basal area) in an aging secondary forest, hypothesizing that this subtle, spatially diffuse disturbance would temporarily decouple C and N cycles by decreasing belowground C allocation and thereby alter N cycling rates and pathways. We postulated that a short-term decrease in ecosystem C uptake and an increase in N leaching would accompany this decoupling, but that concomitant increases in N availability and uptake by later successional species would promote rapid resilience of coupled C-N cycles along new, stable trajectories. Disturbance decreased belowground C allocation and soil respiration, accelerated root turnover, and decreased root mass. These perturbations increased forest floor NH4+ and NO3 availability and NO emission, and declining root function caused water stress and N deficiency in senescent trees. Foliar N and leaf area increased in later successional trees, suggesting that enhanced N uptake supported new leaf area production. Two years after disturbance, N leaching losses and the decline in net ecosystem CO2 exchange were small, suggesting that coupled C-N cycling was resilient to this subtle experimental disturbance. Therefore, compared with the severe disturbances reported in the literature, our subtle disturbance likely will have different effects on longer-term forest biogeochemical trajectories.

     


  • Journal: Journal Of Geophysical Research
  • Funding Agency: —
  • Citation Information:
  • Volume: 116
  • No: G04016
  • Pages: n/a-n/a
  • Publication Year: 2011
  • DOI: 10.1029/2011JG001758