Grazing increases below-ground biomass and net primary production in a temperate grassland

Published in Plant and Soil, v. 392:155–162
Authors

López-Mársico, L., Altesor, A., Oyarzabal, M., Baldassini, P. and Paruelo, J.M.
Publication year 2015
DOI http://dx.doi.org/10.1007/s11104-015-2452-2
Affiliations
  • Instituto de Ecología y Ciencias Ambientales, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400, Montevideo, Uruguay
  • Instituto de Ecología y Ciencias Ambientales, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400, Montevideo, Uruguay
  • Laboratorio de Análisis Regional y Teledetección and Departamento de Métodos Cuantitativos y Sistemas de Información, IFEVA and Facultad de Agronomía, Universidad de Buenos Aires and CONICET, Av. San Martín 4453, C1417DSE, Buenos Aires, Argentina
  • Laboratorio de Análisis Regional y Teledetección and Departamento de Métodos Cuantitativos y Sistemas de Información, IFEVA and Facultad de Agronomía, Universidad de Buenos Aires and CONICET, Av. San Martín 4453, C1417DSE, Buenos Aires, Argentina
  • Instituto de Ecología y Ciencias Ambientales, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400, Montevideo, Uruguay, Laboratorio de Análisis Regional y Teledetección and Departamento de Métodos Cuantitativos y Sistemas de Información, IFEVA and Facultad de Agronomía, Universidad de Buenos Aires and CONICET, Av. San Martín 4453, C1417DSE, Buenos Aires, Argentina
IAI Program

CRN3
IAI Project CRN3095
Keywords
C sequestration
Grazed-ungrazed
Root distribution
Soil cores
CENTURY model
Uruguay

Abstract

  • Background and aims

Grazing can affect the stock and flow of C between above and below-ground vegetation layers. Components of below-ground stratum are one of the less studied. The goals of this research were: 1) to characterize and estimate the vertical distribution of below-ground biomass in grazed and ungrazed areas during a growing season, and 2) to evaluate grazing effects on below-ground net primary production (BNPP).

  • Methods

Below-ground biomass was cored four times to 100 cm depth during a growing season on three paired grazed-ungrazed areas in South-central Uruguayan grasslands. BNPP was estimated using both field data and CENTURY model.

  • Results

On average, below-ground biomass was higher in grazed (1417 gm&minus2) than in ungrazed areas (945 gm&minus2) and showed a marked reduction in relation with soil depth. Turnover rates were 0.40 and 0.37 years&minus1 in grazed and ungrazed areas respectively. Field data and CENTURY simulation showed higher BNPP in grazed areas (1.86 0.77 gm&minus2days&minus1 respectively) than in ungrazed areas (1.07 0.67 gm&minus2days&minus1 respectively).

  • Conclusions

Grazed areas showed higher below-ground biomass, BNPP and turnover that ungrazed areas. Grazing has an important role in regulating both stock and dynamics of C in grassland ecosystems.