El efecto de las plantaciones forestales sobre el funcionamiento de los ecosistemas sudamericanosThe effect of tree plantations on south american ecosystems functioning

El establecimiento de plantaciones forestales sobre áreas bajo vegetación original o uso agrícolo-ganadero se expande en la mayoría de los países de Sudamérica, incentivado por los altos rendimientos, el apoyo fiscaly por el inminente comercio de bonos de carbono. En este trabajo se evaluó cómo esta transformación afecta la producción de biomasa y la dinámica del agua sintetizando información preexistente y original. Mediciones satelitales muestran que el “Índice de Vegetación de Diferencias Normalizadas” (NDVI) de las plantaciones forestales superó a la de la matriz del paisaje agrícolo-ganadera en todos los países y regiones ecológicas analizadas y – con excepción de los bosques valdivianos - a todos los tipos de vegetación original. A escala regional, este aumento en la productividad fue acompañado en el litoral del Río Uruguay por una mayor evapotranspiración y un menor rendimiento hidrológico que redujo a la mitad el caudal de cuencas forestadas, en acuerdo con lo observado en pastizales forestados de la región. Es apremiante generar información acerca de otros impactos de las forestaciones tales como cambios en la dinámica del fuego y el avance de especies invasoras. Reconocer integralmente la influencia de las forestaciones sobre la producción de servicios y bienes permitirá plantear sistemas y políticas forestales más sustentables y útiles para la sociedad.Abstract The establishment of tree plantations on natural or rangenland/cropland areas is increasing in many countries of South America, motivated by high production rates, governmental incentives and a prospective carbon market In this work we evaluated how this land use transformation affects the primary productivity and the water dynamics, summarizing preexistent and original information. Satellite measurements showed that the “Normalized Difference Vegetation Index” (NDVI) of tree plantations exceeded that of the rangeland/cropland landscape matrixes in all analyzed countries and ecological regions. With the exception of the Valdivian forests, tree plantations also displayed higher NDVI values than the original vegetation types. At a regional scale, this increased productivity was accompanied – in the Río Uruguay margins - by higher evapotranspiration rates and consequently, lower water yields of the afforested catchments. It is urgent to generate information about other impacts of tree plantations such as changes in fire dynamics or invasive species. An integrative understanding of the infl uence of tree plantations on the production of goods and services will help to development new forestry systems and policies that are more sustainable and useful for society

Comparación de datos de precipitación estimada por Trmm con mediciones en estaciones meteorológicas de Entre Ríos, Argentina

  En la provincia de Entre Ríos (Argentina) la precipitación tiene alto impacto tanto en sector agropecuario como en otros sectores económico-sociales. La precipitación tiene una gran variabilidad y los productos de satélite contienen incertidumbre en sus valores, por lo que resulta necesario confrontar las estimaciones de satélite con las mediciones de pluviómetros en tierra para evaluar el comportamiento a escala local y regional. En este trabajo se analizan los datos de precipitación estimados por satélite de la misión Tropical Rainfall Measuring Mission (TRMM) conjuntamente con mediciones realizadas en seis estaciones meteorológicas, ubicadas en la provincia, durante los años 2010 y 2011. Para cada estación se realizó un análisis de correlación considerando datos diarios de precipitación acumulada en periodos de ocho días y mensuales. Los resultados muestran que con una confianza del 95% no hay diferencias significativas de varianzas para cinco estaciones y que no hay diferencias significativas de medias en ninguna de las estaciones. Resulta que las estaciones presentan correlaciones con valores de r entre 0.10 y 0.7 para datos diarios, entre 0.65 y 0.82 para datos acumulados en periodos de ocho días y entre 0.58 y 0.82 para precipitación mensual, todos los coeficientes son significativos al 95% de confianza

Distribución espacial y controles ambientales de las represas (tajamares) en el Chaco Árido

Las regiones áridas tienen déficit hídrico a lo largo de todo el año, lo cual limita el crecimiento de la vegetación y la provisión de agua para bebida animal. El Chaco Árido (~10 Mha) sostiene una producción ganadera extensiva de baja inversión, basada en cosechar agua de lluvia en represas (tajamares) como principal fuente de abastecimiento de agua. En este trabajo se determinó la distribución espacial de las represas y su relación con el entorno biofísico (precipitación, vegetación, caminos) en el Chaco Árido. Para ello analizamos imágenes satelitales, información vectorial y análisis multivariados sobre una grilla de 135 celdas de 0.25°x0.25° cada una. En total identificamos 7920 represas (1 cada 1230 ha) y observamos densidades máximas de 1 represa cada 185 ha, pero también celdas sin represas, asociadas a la presencia de sierras, salinas y dunas. La densidad de represas fue mayor en celdas con mayor densidad de establecimientos ganaderos, caminos y carga animal (r=0.63, r=0.56 y r=0.51, respectivamente; P<0.01 en todos los casos), y en sitios con mayor precipitación media anual y menor variabilidad interanual (r=0.62 y r=-0.47, respectivamente; P<0.01 para ambos casos). Aunque la precipitación media anual fue el atributo que mejor se asoció a la distribución de las represas a escala regional, dicha relación fue más variable hacia los extremos del gradiente (árido y subhúmedo). Esto puede deberse a factores antrópicos tales como la baja rentabilidad de los sistemas ganaderos y la historia o el cambio en el uso del suelo. Los resultados de este trabajo representan un primer intento para dimensionar la importancia que tienen las represas en el Chaco Árido. Consideramos que este estudio puede ser útil para entender la producción ganadera y también para futuras investigaciones relacionadas con la conservación de la vida silvestre y el desarrollo de poblados rurales en la región.Spatial distribution and environmental controls of dams (small impoundments) in the Arid Chaco. Arid regions are characterized by water shortage throughout the year, which constrains both the vegetation growth and the supply of water for livestock consumption. The Arid Chaco (~10 Mha) hosts extensive and low-investment livestock systems based on rainwater harvesting stored in dams (small impoundments) as the main source of water supply. In this study, we characterized the spatial distribution of dams in the Arid Chaco and analyzed their relationship with biophysical variables (e.g. rainfall, vegetation, roads). For these purposes, we used satellite images, vector information and performed multivariate analysis on a spatial grid of 135 cells of 0.25°x0.25°. In total, 7920 dams were identified (1 dam every 1230 ha), with maximum densities of 1 dam every 185 ha but also cells without dams associated with the presence of mountains, salt flats and dunes. Dam density was higher in cells with higher densities of livestock establishments, roads and cale stock (r=0.63, r=0.56 and r=0.51, respectively; P<0.01 in all cases), and in cells with higher mean annual rainfall and lower interannual rainfall variability (r=0.62 and r=-0.47, respectively; P<0.01 for both cases). Although the mean annual rainfall was the best-associated variable with the distribution of dams at the regional scale, this relationship weakened towards the extremes of the gradient (arid and sub-humid). This may be due to anthropic factors such as the low profitability of livestock systems, the previous land uses or land-use changes. The results of this study represent a first aempt to assess the importance of impoundments in the Arid Chaco. We believe that this study may be useful not only to understand livestock production, but also for future studies related to the conservation of wildlife and the development of rural towns in the region.Instituto de Investigación Animal del Chaco SemiáridoFil: Niborski, Marcos J. Universidad Nacional de San Luis. Grupo de Estudios Ambientales-IMASL. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Niborski, Marcos J. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Manejo y Conservación de Suelos; ArgentinaFil: Murray, Francisco. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Luis. Agencia De Extensión Rural San Luis; ArgentinaFil: Jobbágy, Esteban G. Universidad Nacional de San Luis. Grupo de Estudios Ambientales-IMASL. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nosetto, Marcelo D. Universidad Nacional de San Luis. Grupo de Estudios Ambientales-IMASL. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nosetto, Marcelo D. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias. Cátedra de Climatología; ArgentinaFil: Fernandez, Pedro David. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; ArgentinaFil: Fernandez, Pedro David. Universidad Nacional de Tucumán. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ecología Regional (IER); ArgentinaFil: Castellanos, George. Universidad Nacional de San Luis. Grupo de Estudios Ambientales-IMASL. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Magliano, Patricio N. Universidad Nacional de San Luis. Grupo de Estudios Ambientales-IMASL. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Magliano, Patricio N. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Biología; Argentin

Protecting climate with forests

Policies for climate mitigation on land rarely acknowledge biophysical factors, such as reflectivity, evaporation, and surface roughness. Yet such factors can alter temperatures much more than carbon sequestration does, and often in a conflicting way. We outline a framework for examining biophysical factors in mitigation policies and provide some best-practice recommendations based on that framework. Tropical projects-avoided deforestation, forest restoration, and afforestation-provide the greatest climate value, because carbon storage and biophysics align to cool the Earth. In contrast, the climate benefits of carbon storage are often counteracted in boreal and other snow-covered regions, where darker trees trap more heat than snow does. Managers can increase the climate benefit of some forest projects by using more reflective and deciduous species and through urban forestry projects that reduce energy use. Ignoring biophysical interactions could result in millions of dollars being invested in some mitigation projects that provide little climate benefit or, worse, are counter-productive

Contrasting CO2 and water vapour fluxes in dry forest and pasture sites of central Argentina

The dry forests of South America are a key player of the global carbon cycle and the regional water cycle, but they are being intensively deforested. We used eddy covariance measurements to compare the temporal patterns of CO2 and water vapour fluxes and their relationships with environmental variables in dry forest and pastures sites of central Argentina. Ecosystem fluxes showed clear contrasts in magnitude, timing and response to environmental controls between ecosystems. The dry forest displayed higher daily gross primary productivity (GPP, 10.6 vs. 7.8 g CO2 m−2 d−1) and ecosystem respiration (Reco, 9.1 vs. 7.0 g CO2 m−2 d−1) and lower net ecosystem exchange (NEE, −1.5 vs. −0.7 g CO2 m−2 d−1) than the pasture. These differences were explained by a lower tolerance of the pasture to cool temperatures and drought. The lowest NEE rates were observed between 26°C and 34°C in the pasture, but below this range, NEE increased sharply, switching to a carbon source with temperatures <20°C. By contrast, the dry forest remained as a strong carbon sink down to 18°C. The pasture also showed a stronger drop of GPP with drought compared with the dry forest, becoming a carbon source with soil wetness <25% of soil available water. Rainfall was strongly coupled with GPP in both ecosystems, but the dry forest responded to longer rainfall integration periods. This study helps to understand how ecosystems can respond to climate change, improve global scale modelling and increase the productivity and resilience of rangelands.Fil: Nosetto, Marcelo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Luna Toledo, Emanuel Santiago. Instituto Nacional de Tecnología Agropecuaria; Argentina. Universidad Nacional de Chilecito; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Magliano, Patricio Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Figuerola, Patricia Irene. Universidad Nacional de Chilecito; ArgentinaFil: Blanco, Lisandro Javier. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Jobbagy Gampel, Esteban Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; Argentin

The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data

The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible.Peer reviewe

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km² resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e., offset) between in-situ soil temperature measurements, based on time series from over 1200 1-km² pixels (summarized from 8500 unique temperature sensors) across all the world’s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in-situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world\u27s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Global maps of soil temperature.

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications