Modelling aboveground net primary production (ANPP) of an Atlantic mountain grassland based on time series approach

Abstract

Because primary productivity is related both with the energy that sustains food webs and with species diversity, it is usually considered a key ecosystem property and a reliable indicator of available forage. In this work the aboveground net primary production (ANPP) of an Atlantic mountain grassland system was modelled in order to attempt producing short-term forecasts. Since grazing influences productivity, two treatment levels (grazing and exclusion) were experimentally applied in each of three field sites. Monthly ANPP data were then collected over three consecutive vegetative periods (2006-2008), thereby obtaining six time series (one per plot). Since no significant differences among sites (within treatments) were found, these six series were later reduced through averaging to only two series (one per treatment level). Two kinds of statistical models were then used to attempt monthly ANPP forecasting: exponential smoothing methods and ARIMA models. Both methodologies turned out to produce inadequate forecasts due to the presence of marked local features (innovative outliers) in our relatively short time-series data. Nonetheless, useful information for a more innovative shepherding management was revealed (e.g. the presence of within-year variation in ANPP, and differences between the grazing and exclusion treatments). Longer data series, which would require a more demanding effort in sampling investment, are likely necessary in order to obtain adequate forecasts using these time series methodologies.

High-Andean wetland of Peru: Floristic diversity, primary net aerial productivity, ecological condition, and carrying capacity

“…Diversos autores indican que, el conocimiento de la diversidad florística en relación al potencial de la productividad primaria neta aérea en los humedales, tiene alto valor para el ecosistema y la socio economía rural (Siguayro, 2008;Yaranga et al, 2018;Salaberria et al, 2019); por lo que debe ser cuantificado, mediante el uso de diversos indicadores ecológicos y productivos (Moreno, 2001;Ramírez, 2011;Chanamé et al, 2019). La valoración de los indicadores ecológicos es abordada desde diversos criterios, siendo el índice de Shannon Wiener el más difundido para estudios vegetales (Moreno, 2001) UAl/ha/año en época lluviosa y 2,70 UAl/ha/año; Alvarado (2018) encontró en el Parque Nacional de Huascarán una capacidad de carga de 0,13 UA/ha/año en una condición de pastizal pobre; Portal (2019) encontró en 3 humedales de Ayacucho capacidad de carga de 2,52 UAl/ha/año para 65 cm de profundidad de la napa freática, 2,60 UAl/ha/año para 18 cm y 2,80 UAl/ha/año para 15 cm, concluyendo que a mayor profundidad de la napa freática menor capacidad de carga animal.…”

Modeling NPP and NDVI time series in different bioclimatic regions of Iran

“…They result showed two approaches can generate insu cient predictions given the existence of pronounced locally characters (new outliers) in our relative low time-series data. Nevertheless, advantageous data to an initiative grazing management was indicated (for example the existence of yearly changes in ANPP, as well as discrepancies between the graze and exclusions treatment) (Salaberria et al, 2019).…”