Abstract
Net primary production (NPP) is defined as the rate at which biomass accumulates per unit area and time and is considered an integrating variable of the ecosystem function. Deforestation and land use changes observed in the semi-arid Chaco region may affect total C gains and seasonality. Previous work in the region uses spectral vegetation indexes as a subrogate of the NPP. However, they arrive at contrary results and only concluded about to what happens with the aboveground production, without considering the changes that occur in the belowground production, which usually varies between physiognomic types of vegetation. Based on the model of radiation use efficiency, spectral information obtained from remote sensing and BNPP/NPP relationships of the bibliography, the goal of this work was to quantify the effect of the land use and cover change on the NPP and its seasonal variation. Specially, we evaluated the change on NPP in agricultural and silvopastoral systems with a variable woody component respect to the original forest. NPP and its seasonal variation of the main land uses of the semi-arid Chaco region. We observed that, in general, the land uses that showed higher aboveground productivity showed, at the same time, the lower levels of belowground productivity. The double wheat-maize crop presented the highest total NPP, significantly higher than that of the silvopastoral systems between 5 and 25% of tree cover, and to the wheat-soybean and soybean crops. However, their productivity did not vary significantly from that of the native forest, the tropical pastures and the maize. The results obtained not only provide substantial information to conclude quantitatively in terms of the magnitude of the change in units of dry matter, but also allow to establish a more appropriate order or ranking of land uses in terms of total productivity.https://doi.org/10.25260/EA.20.30.1.0.961
Highlights
Agricultural and silvopastoral systems in the semi-arid Chaco
Previous work in the region uses spectral vegetation indexes as a subrogate of the Net primary production (NPP). They arrive at contrary results and only concluded about to what happens with the aboveground production, without considering the changes that occur in the belowground production, which usually varies between physiognomic types of vegetation
Based on the model of radiation use efficiency, spectral information obtained from remote sensing and BNPP/NPP relationships of the bibliography, the goal of this work was to quantify the effect of the land use and cover change on the NPP and its seasonal variation
Summary
El área de estudio se localizó en el Departamento de Anta, al sudeste de la provincia de Salta, que limita con las provincias de Chaco y Santiago del Estero (Figura 1). Buena parte del área también resulta apta para cultivos de maíz y trigo, que crecieron en superficie durante los últimos años (Baumann et al 2017). La agricultura se caracteriza por ser de secano (con excepción de los sitios localizados en las inmediaciones del Río Juramento, en la porción sudeste del Departamento de Anta). La ganadería extensiva también ganó impulso en los últimos años, lo que promovió el reemplazo del bosque nativo por pasturas megatérmicas exóticas (Gasparri et al 2013; Volante et al 2016). Se utilizan rolos para remover parcialmente la vegetación leñosa dejando en pie solo los árboles de mayor porte y, al mismo tiempo, sembrar semillas de pastos megatérmicos (Kunst et al 2014)
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