title: Vegetation Productivity in Natural vs. Cultivated Systems along Water Availability Gradients in the Dry Subtropics.
abstract: The dry subtropics are subject to a rapid expansion of crops and pastures over vast areas of natural woodlands and savannas. In this paper, we explored the effect of this transformation on vegetation productivity (magnitude, and seasonal and long-term variability) along aridity gradients which span from semiarid to subhumid conditions, considering exclusively those areas with summer rains (>66%). Vegetation productivity was characterized with the proxy metric "Enhanced Vegetation Index" (EVI) (2000 to 2012 period), on 6186 natural and cultivated sampling points on five continents, and combined with a global climatology database by means of additive models for quantile regressions. Globally and regionally, cultivation amplified the seasonal and inter-annual variability of EVI without affecting its magnitude. Natural and cultivated systems maintained a similar and continuous increase of EVI with increasing water availability, yet achieved through contrasting ways. In natural systems, the productivity peak and the growing season length displayed concurrent steady increases with water availability, while in cultivated systems the productivity peak increased from semiarid to dry-subhumid conditions, and stabilized thereafter giving place to an increase in the growing season length towards wetter conditions. Our results help to understand and predict the ecological impacts of deforestation on vegetation productivity, a key ecosystem process linked to a broad range of services.
authors.affiliation: Grupo de Estudios Ambientales, IMASL, Universidad Nacional de San Luis & CONICET, San Luis, Argentina.
authors.forename: Germán
authors.initials: G
authors.lastname: Baldi
authors.affiliation: Laboratorio de Análisis Regional y Teledetección, IFEVA, Universidad de Buenos Aires & CONICET, Buenos Aires, Argentina.|Departamento de Métodos Cuantitativos y Sistemas de Información, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Marcos
authors.initials: M
authors.lastname: Texeira
authors.affiliation: Grupo de Estudios Ambientales, IMASL, Universidad Nacional de San Luis & CONICET, San Luis, Argentina.|A.E.R. San Luis, Instituto Nacional de Tecnología Agropecuaria, San Luis, Argentina.
authors.forename: Francisco
authors.initials: F
authors.lastname: Murray
authors.affiliation: Grupo de Estudios Ambientales, IMASL, Universidad Nacional de San Luis & CONICET, San Luis, Argentina.
authors.forename: Esteban G
authors.initials: EG
authors.lastname: Jobbágy
mesh_terms: D057231:Climate Change; D018556:Crops, Agricultural / Q000254:growth & development*; D017753:Ecosystem; D063245:Plant Development; D018521:Plant Physiological Phenomena; D014329:Tropical Climate; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water