Ecosystem functional changes associated with land clearing in NW Argentina.

Published in Agriculture, Ecosystem & Environment, v. 154:12-22
Authors

Volante, J.N., Alcaraz-Segura, D., Mosciaro, M.J., Viglizzo, E.F. and Paruelo, J.M.
Publication year 2012
DOI https://doi.org/10.1016/j.agee.2011.08.012
Affiliations
  • Laboratorio de Teledetección y SIG, INTA Salta, Ruta Nacional 68, km 172, Salta, Argentina
  • Laboratorio de Análisis Regional y Teledetección, Departamento de Métodos Cuantitativos y Sistemas de información, Facultad de Agronomía and IFEVA, Universidad de Buenos Aires and CONICET. Avda. San Martín, 4453, Buenos Aires 1417, Argentina
  • Centro Andaluz para la Evaluación y Seguimiento del Cambio Global, Departamento de Biología Vegetal y Ecología, Universidad de Almería, Ctra. Sacramento s/n, Almería 04120, Spain
  • INTA Centro Regional La Pampa &ndash San Luis, La Pampa, Argentina

 
IAI Program

CRN3
IAI Project CRN3095
Keywords
Carbon gain dynamics
Deforestation
Inter-annual variability
Net primary production
Remote sensing
Intermediate ecosystem services
Subtropical South America

Highlights

  • We assessed the spatial magnitude of deforestation and the impact of converting natural habitats into croplands and grazing lands on ecosystem functional attributes areas of NW Argentina.
  • Land clearing had a larger impact on the seasonality of C gains than in the total amount of C fixed.
  • Land clearing also increased the magnitude of inter-annual anomalies and the inter-annual variability of C gains dynamics.

Abstract

We assessed the extension of natural habitat conversion into croplands and grazing lands in subtropical NW Argentina and its impact on two key ecosystem functional attributes. We quantified changes in remotely sensed surrogates of aboveground net primary production (ANPP) and seasonality of carbon gains. Both functional attributes are associated with intermediate ecosystem services sensu Fisher et al. (2009). Deforestation was estimated based on photointerpretation of Landsat imagery. The seasonal dynamics of the MODIS satellite Enhanced Vegetation Index (EVI) was used to calculate the EVI annual mean as a surrogate of ANPP, and the EVI seasonal coefficient of variation as an indicator of seasonal variability of carbon gains. The 2000&ndash2007 period showed a high rate of land clearing: 5.9% of NW Argentina (1,757,600 ha) was cleared for agriculture and ranching, corresponding to an annual rate of 1.15%. Dry forests experienced the highest rate and humid forests the lowest. Though land clearing for agriculture and ranching had relatively small impacts on total annual ANPP, once deforested, parcels significantly became more seasonal than the natural vegetation replaced. Such increase in seasonality is associated with a reduction of photosynthetic activity during a portion of the year (fallow). Direct consequences of this reduction can be expected on several ecosystem services such as erosion control and water regulation, due to greater exposure of bare soil, and biodiversity, due to the loss or decline in habitat quality and the decrease of green biomass availability for primary consumers during fallow. Land clearing also increased the magnitude of inter-annual differences in C gains, suggesting a greater buffer capacity against climate fluctuations of natural vegetation compared to croplands.