Carbon and nitrogen dynamics in a successional agroforestry system in the Neotropics

The present study aimed to assess the effect of fourteen years of implementation of a successional and biodiverse agroforestry system (AFS) in a degraded agricultural field located in the Cerrado region of Central Brazil on the carbon and nitrogen dynamics. To track short term soil N dynamics we sampled instantaneous soil N rates in four seasonal periods (wet-dry, dry, dry-wet, wet) and to track long term C and N dynamics we measured C and N stable isotopes in the plant-litter-soil system. As additional data we determined the aboveground biomass; resorption rates of foliar and, soil C and N stocks. The measured aboveground biomass was 19.2 Mg C ha-1. The mean resorption rate of foliar N was 49.3%. C:N ratio was 20.4 ± 1.4 and 14.2 ± 0.32 in the litter layer and the topsoil, respectively. Soil N-NH4+ was predominant over N-NO3-. After 40 days, the cumulative N-N2O emission was 0.33 kg ha-1. The mean C and N stocks were 3.8 Mg N ha-1 and 43.6 Mg C ha-1, respectively. The averaged soil δ15N was 6.8‰. Soil δ13C was -20.3‰. After 14 years of implementation, approximately 40% of the total C in the topsoil (0-20 cm depth) was derived from the AFS biomass input, predominantly from the C3 photosynthetic pathway. The studied biodiverse AFS that replaced a degraded agricultural field in the Cerrado region showed to be responsive both in terms of soil and plant C and N pools and fluxes.

Download Full-text

Changes induced by elk browsing in the aboveground biomass production and distribution of willow (Salix monticola Bebb): their relationships with plant water, carbon, and nitrogen dynamics

Oecologia ◽

10.1007/s004420000593 ◽

2001 ◽

Vol 127 (3) ◽

pp. 334-342 ◽

Cited By ~ 42

Author(s):

H. Raul Peinetti ◽

Romulo S.C. Menezes ◽

Michael B. Coughenour

Keyword(s):

Biomass Production ◽

Aboveground Biomass ◽

Nitrogen Dynamics ◽

Plant Water ◽

Carbon And Nitrogen ◽

Production And Distribution ◽

Carbon And Nitrogen Dynamics ◽

Salix Monticola

Download Full-text

PEATBOG: a biogeochemical model for analyzing coupled carbon and nitrogen dynamics in northern peatlands

Geoscientific Model Development ◽

10.5194/gmd-6-1173-2013 ◽

2013 ◽

Vol 6 (4) ◽

pp. 1173-1207 ◽

Cited By ~ 19

Author(s):

Y. Wu ◽

C. Blodau

Keyword(s):

Soil Moisture ◽

Nitrogen Deposition ◽

Vegetation Change ◽

Nitrogen Dynamics ◽

Biogeochemical Model ◽

Litter Production ◽

Carbon And Nitrogen ◽

Carbon And Nitrogen Dynamics ◽

C And N ◽

Northern Peatlands

Abstract. Elevated nitrogen deposition and climate change alter the vegetation communities and carbon (C) and nitrogen (N) cycling in peatlands. To address this issue we developed a new process-oriented biogeochemical model (PEATBOG) for analyzing coupled carbon and nitrogen dynamics in northern peatlands. The model consists of four submodels, which simulate: (1) daily water table depth and depth profiles of soil moisture, temperature and oxygen levels; (2) competition among three plants functional types (PFTs), production and litter production of plants; (3) decomposition of peat; and (4) production, consumption, diffusion and export of dissolved C and N species in soil water. The model is novel in the integration of the C and N cycles, the explicit spatial resolution belowground, the consistent conceptualization of movement of water and solutes, the incorporation of stoichiometric controls on elemental fluxes and a consistent conceptualization of C and N reactivity in vegetation and soil organic matter. The model was evaluated for the Mer Bleue Bog, near Ottawa, Ontario, with regards to simulation of soil moisture and temperature and the most important processes in the C and N cycles. Model sensitivity was tested for nitrogen input, precipitation, and temperature, and the choices of the most uncertain parameters were justified. A simulation of nitrogen deposition over 40 yr demonstrates the advantages of the PEATBOG model in tracking biogeochemical effects and vegetation change in the ecosystem.

Download Full-text