Livestock exclusion reduces the temporal stability of grassland productivity regardless of eutrophication

Changes in livestock loads and eutrophication associated with human activities can modify the stability of grassland's aboveground net primary productivity (ANPP), by modifying the mean (μ) and/or standard deviation (σ) of ANPP. The changes in attributes of the plant community (i.e., species richness, species asynchrony, dominance) might in turn explain the ecosystem temporal (inter-annual) stability of grassland production. Here, we evaluated the interactive effects of changes in livestock loads and chronic nutrient addition on the temporal stability of ANPP (estimated as μ/σ) in temperate grasslands. We also assessed the role of different attributes of the plant community on ecosystem stability. We carried out a factorial experiment of domestic livestock exclusion and nutrient addition (10 g.m−2.year−1 of nitrogen, phosphorus, and potassium; n = 6 blocks) during five consecutive years in a natural grassland devoted to cattle production (Flooding Pampa, Argentina). Domestic livestock exclusion reduced ANPP stability by 65%, regardless of nutrient load, mainly by the increase of ANPP standard deviation. This reduction in ANPP stability after livestock exclusion was associated mostly with higher plant species dominance and also with reductions in plant effective richness and in the asynchrony of grassland's species. Despite not finding direct negative effects of eutrophication on ANPP stability, chronic nutrient addition decreased effective species richness and asynchrony, which may translate into reductions in ANPP stability in the future. Our findings highlight that the presence of livestock maintains the temporal stability of ANPP mainly by lowering the dominance of the plant community. However, increases in nutrient loads in grasslands devoted to livestock production may threaten grassland's stability.Fil: Campana, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente; ArgentinaFil: Tognetti, Pedro Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; ArgentinaFil: Yahdjian, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente; Argentin

Pampean-grassland heterogeneity on the intersection of science, art, and culture

Since prehistoric times, temperate grasslands have provided favorable habitat for human subsistence. Ease of exploitation, however, has caused that temperate grasslands are among the most destroyed terrestrial ecosystems. The region known as the Pampas or Rio de la PlataGrasslands, extending over some 750,000 sq. km in central eastern Argentina, Uruguay and southern Brazil, comprises the largest temperate grassland area in the southern hemisphere. Flat topography, humid temperate climate, grassy natural vegetation, and absence of large native herbivores have conditioned multiple aspects of human life in the region, like patterns of population settlement, techniques for acquisition and transportation of goods, aesthetic preferences, and social structure. In this article, we present some writers inspired by the Pampas, we briefly summarize the main results of scientific research on the drivers of vegetation physiognomy and heterogeneity in the Pampas, based on the invaluable floristic database compiled by Professor Rolando J. C. León, and we sketch one of Professor León´s scientific-historic tours to the Pampas. Finally, we call attention to currently threats to the persistence of Pampean Grassland.Fil: Perelman, S.B.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Omacini, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Tognetti, Pedro Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Batista, William B.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

Imperfect Vertical Transmission of the Endophyte Neotyphodium in Exotic Grasses in Grasslands of the Flooding Pampa

Fil: Gundel, Pedro E. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas vinculadas a la Agricultura; Argentina.Fil: Garibaldi, Lucas Alejandro. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio Ecotono; Argentina.Fil: Tognetti, Pedro M. Universidad de Buenos Aires (UBA). Facultad de Agronomía; Argentina.Fil: Aragón, Roxana. Universidad de Buenos Aires (UBA). Facultad de Agronomía; Argentina.Fil: Ghersa, Claudio M. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas vinculadas a la Agricultura; Argentina.Fil: Omacini, Marina. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas vinculadas a la Agricultura; Argentina.Fil: Gundel, Pedro E. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Garibaldi, Lucas Alejandro. Universidad de Buenos Aires (UBA). Facultad de Agronomía; Argentina.Fil: Ghersa, Claudio M. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Omacini, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Cool-season grasses establish symbioses with vertically transmitted Neotyphodium endophytes widespread in nature. The frequency of endophyte-infected plants in closed populations (i.e., without migrations) depends on both the differential fitness between infected and non-infected plants, and the endophyte-transmission efficiency. Most studies have been focused on the first mechanism ignoring the second. Infection frequency and endophyte transmission from vegetative tissues to seeds were surveyed in two grasses growing in vegetation units that differ in flood and grazing regimes, and soil salinity. Transmission efficiency and infection frequency for tall fescue did not vary significantly and were 0.98 and 1.00, respectively. For Italian ryegrass, transmission efficiency and infection frequency were 0.88 and 0.57 in humid prairies, and 0.96 and 0.96 in the other vegetation units. Only in humid mesophytic meadows, the observed pattern was irrespective of the presence or absence of grazers. Our results suggest that selection forces for endophyte infection are different for both species. Imperfect transmission was only compensated in tall fescue through an increased fitness of infected plants. Interpreting variations of infection frequency only in terms of differential fitness can be misleading, considering that endophyte transmission can be imperfect and variable in nature. Therefore, this study highlights the importance of measuring transmission efficiency

Seed dormancy and germination of native and invasive alien woody species of an endangered temperate forest in the Argentine Pampas

Forest restoration plans can benefit from knowledge of seed ecophysiology. Naturally, seeds respond to environmental clues to trigger germination or persist in the seed bank. Controlling dormancy and germination moment in native species will allow more efficient seed management, both for direct seeding (in situ restoration) and for native plant cultivation in nurseries (ex situ restoration). In addition, the differences in germination conditions of native and alien invasive trees can be used as control windows of the alien species in the seed bank. The aim of this study was to identify the environmental factors regulating seed dormancy and germination of native and alien trees of the Talares, an endangered temperate forest of the Argentine Pampas region. Seeds of the native trees Schinus longifolius, Jodina rhombifolia, Celtis tala and the alien trees, Ligustrum lucidum, Ligustrum sinense and Gleditsia triacanthos were collected and the presence of dormancy was determined exposing the seeds to standard germination protocols. In case of dormancy presence, a post-maturation experiment was carried out in two conditions: i) cold and wet (stratification) and ii) dry and warm (after-ripening). The native species J. rhombifolia and C. tala showed seed dormancy but S. longifolius did not. For C. tala germination it was necessary a previous post-maturing process; however, environmental conditions for J. rhombifolia germination were not attained. Alien species showed a high germination, reaching up to 100% in at least one of the evaluated conditions, and displayed different emergence windows compare to natives. Since alien species germinated at lower temperatures than natives, a temporal window for chemical or mechanical control is proposed. Ecophysiology of seed dormancy and germination facilitates strategies for decision makers, as it can make native seeds use and aliens control more efficient to meet global restoration goals.Fil: Lacoretz, Mariela Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología Funcional; ArgentinaFil: Malavert Pineda, Cristian Jonatan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Madanes, Nora. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología Funcional; ArgentinaFil: Cristiano, Piedad María. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología Funcional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Tognetti, Pedro Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

General destabilizing effects of eutrophication on grassland productivity at multiple spatial scales

Fil: Hautier, Yann. Utrecht University. Department of Biology. Ecology and Biodiversity Group. The Netherlands.Fil: Zhang, Pengfei. Utrecht University. Department of Biology. Ecology and Biodiversity Group. The Netherlands. - Lanzhou University State. School of Life Science. Key Laboratory of Grassland and Agro - Ecosystems. People’s Republic of China. - Institute of Eco-Environmental Forensics of Shandong University. People’s Republic of China. - Ministry of Justice Hub for Research and Practice in Eco - Environmental Forensics. People’s Republic of China.Fil: Loreau, Michael. Centre for Biodiversity Theory and Modelling. Theoretical and Experimental Ecology Station.CNRS. France.Fil: Wilcox, Kevin R. University of Wyoming. Department of Ecosystem Science and Management. Laramie, WY, USA.Fil: Seabloom, Eric W. University of Minessota. Department of Ecology, Evolution, and Behavior. Minessota, USA.Fil: Tognetti, Pedro Maximiliano. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina. - CONICET – Universidad de Buenos Aires. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Eutrophication is a widespread environmental change that usually reduces the stabilizing effect of plant diversity on productivity in local communities. Whether this effect is scale\ndependent remains to be elucidated. Here, we determine the relationship between plant diversity and temporal stability of productivity for 243 plant communities from 42 grasslands\nacross the globe and quantify the effect of chronic fertilization on these relationships.\nUnfertilized local communities with more plant species exhibit greater asynchronous dynamics among species in response to natural environmental fluctuations, resulting in greater local stability (alpha stability). Moreover, neighborhood communities that have greater spatial variation in plant species composition within sites (higher beta diversity) have greater spatial synchrony of productivity among communities, resulting in greater stability at the larger scale (gamma stability). Importantly, fertilization consistently weakens the contribution of plant diversity to both of these stabilizing mechanisms, thus diminishing the positive effect of biodiversity on stability at differing spatial scales. Our findings suggest that preserving grassland functional stability requires conservation of plant diversity within and among ecological communities.grafs

Recordando a Silvia Burkart (07/12/1942-17/01/2018)

Tognetti, Pedro Maximiliano. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Omacini, Marina. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Oyarzabal, Mariano. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Striker, Gustavo Gabriel. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.606-60

Nutrient addition shifts plant community composition towards earlier flowering species in some prairie ecoregions in the U.S. Central Plains

e0178440, 15 p.The distribution of flowering across the growing season is governed by each species' evolutionary history and climatic variability. However, global change factors, such as eutrophication and invasion, can alter plant community composition and thus change the distribution of flowering across the growing season. We examined three ecoregions (tall-, mixed, and short-grass prairie) across the U.S. Central Plains to determine how nutrient (nitrogen (N), phosphorus, and potassium (+micronutrient)) addition alters the temporal patterns of plant flowering traits. We calculated total community flowering potential (FP) by distributing peakseason plant cover values across the growing season, allocating each species' cover to only those months in which it typically flowers. We also generated separate FP profiles for exotic and native species and functional group. We compared the ability of the added nutrients to shift the distribution of these FP profiles (total and sub-groups) across the growing season. In all ecoregions, N increased the relative cover of both exotic species and C3 graminoids that flower in May through August. The cover of C4 graminoids decreased with added N, but the response varied by ecoregion and month. However, these functional changes only aggregated to shift the entire community's FP profile in the tall-grass prairie, where the relative cover of plants expected to flower in May and June increased and those that flower in September and October decreased with added N. The relatively low native cover in May and June may leave this ecoregion vulnerable to disturbance induced invasion by exotic species that occupy this temporal niche. There was no change in the FP profile of the mixed and short-grass prairies with N addition as increased abundance of exotic species and C3 graminoids replaced other species that flower at the same time. In these communities a disturbance other than nutrient addition may be required to disrupt phenological patterns

Interaction between cash crops and cover crops: Production, soil water and nitrates dynamic

El agua y el nitrógeno (N) son los factores que generan las mayores limitaciones en la producción de alimentos. El uso de los cultivos de cobertura (CC), modifica la dinámica del agua y N del suelo, por lo que es importante conocer su interacción con los cultivos comerciales. Los objetivos de este trabajo fueron (1) evaluar el efecto del centeno como CC y los cultivos de soja y maíz sobre la dinámica del agua y el N y (2) la sinergia entre el CC y los comerciales. Para tales objetivos se tomaron muestras de material vegetal para medir la producción de materia seca (MS) del centeno y el rendimiento de soja y maíz y muestras de suelo para medir el contenido de agua y N disponible de un ensayo de larga duración ubicado en General Villegas (Buenos Aries). El ensayo se dividió en parcelas principales (monocultivo de soja, monocultivo de maíz y rotación soja/maíz) y subparcelas de tratamientos de invierno (barbecho, CC y CC fertilizado). Los resultados muestran que la producción de MS del CC fue incrementada (entre un 30 y 150%) debido a la fertilización y al cultivo de soja como predecesor. No se observaron en general diferencias en el agua disponible por el uso del CC. Con respecto al N, se observó una disminución debido al consumo del CC dentro de los tratamientos con soja. Finalmente, los rendimientos de los cultivos comerciales no fueron afectados, salvo un año donde la producción del maíz fue superior sin CC (entre 1000 y 2000 kg ha-1). Por lo tanto, el CC generó MS durante el invierno sin afectar la disponibilidad de agua para los cultivos posteriores, disminuyendo pérdidas de N del sistema. Sin embargo, es necesario ajustar el manejo del CC según las perspectivas climáticas y el cultivo comercial.Water and nitrogen (N) are the main factors that generate the greatest limitations in food production. The use of cover crops (CC) due to their multiple benefits, can modify soil water and nitrate dynamic. It is therefore important to know the interaction between cash crops and CC. The objectives of this work were to evaluate the interaction between rye as CC and cash crops over the dynamics of water and N; and the synergy between crops. For these objectives, samples were taken to measure soybean and corn yield and rye dry matter production (DM) and soil samples to measure evolution of the water content and available N as nitrate due to the presence of the different crops in a long-term experiment located in General Villegas (Buenos Aries) during the 2010/11, 2011/12 and 2012/13 period. As a result, the DM production of the CC was increased (between 30 and 150%) with soybeans as a predecessor and when it was fertilized. No differences in general were observed in the availability of water due to the use of CC. Regarding the concentration of N in soil, it was observed a decrease of it concentration probably due to the consumption of CC in the soybean treatments. Finally, the yields of cash crops in general were not affected, except for a single year where corn production was statistically higher in the treatment without CC (between 1000 and 2000 kg ha-1). Therefore, it is necessary to adjust CC management according to climatic situations and the cash crop.Fil: Beltran, Marcelo Javier. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Suelos; ArgentinaFil: Galantini, Juan Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Tognetti, Pedro Maximiliano. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Barraco, Miriam. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Buenos Aires Norte. Estacion Experimental Agropecuaria General Villegas. Agencia de Extension Rural General Villegas.; Argentin

Interaction between cash crops and cover crops: Production, soil water and nitrates dynamic

El agua y el nitrógeno (N) son los factores que generan las mayores limitaciones en la producción de alimentos. El uso de los cultivos de cobertura (CC), modifica la dinámica del agua y N del suelo, por lo que es importante conocer su interacción con los cultivos comerciales. Los objetivos de este trabajo fueron (1) evaluar el efecto del centeno como CC y los cultivos de soja y maíz sobre la dinámica del agua y el N y (2) la sinergia entre el CC y los comerciales. Para tales objetivos se tomaron muestras de material vegetal para medir la producción de materia seca (MS) del centeno y el rendimiento de soja y maíz y muestras de suelo para medir el contenido de agua y N disponible de un ensayo de larga duración ubicado en General Villegas (Buenos Aries). El ensayo se dividió en parcelas principales (monocultivo de soja, monocultivo de maíz y rotación soja/maíz) y subparcelas de tratamientos de invierno (barbecho, CC y CC fertilizado). Los resultados muestran que la producción de MS del CC fue incrementada (entre un 30 y 150%) debido a la fertilización y al cultivo de soja como predecesor. No se observaron en general diferencias en el agua disponible por el uso del CC. Con respecto al N, se observó una disminución debido al consumo del CC dentro de los tratamientos con soja. Finalmente, los rendimientos de los cultivos comerciales no fueron afectados, salvo un año donde la producción del maíz fue superior sin CC (entre 1000 y 2000 kg ha-1). Por lo tanto, el CC generó MS durante el invierno sin afectar la disponibilidad de agua para los cultivos posteriores, disminuyendo pérdidas de N del sistema. Sin embargo, es necesario ajustar el manejo del CC según las perspectivas climáticas y el cultivo comercial.Water and nitrogen (N) are the main factors that generate the greatest limitations in food production. The use of cover crops (CC) due to their multiple benefits, can modify soil water and nitrate dynamic. It is therefore important to know the interaction between cash crops and CC. The objectives of this work were to evaluate the interaction between rye as CC and cash crops over the dynamics of water and N; and the synergy between crops. For these objectives, samples were taken to measure soybean and corn yield and rye dry matter production (DM) and soil samples to measure evolution of the water content and available N as nitrate due to the presence of the different crops in a long-term experiment located in General Villegas (Buenos Aries) during the 2010/11, 2011/12 and 2012/13 period. As a result, the DM production of the CC was increased (between 30 and 150%) with soybeans as a predecessor and when it was fertilized. No differences in general were observed in the availability of water due to the use of CC. Regarding the concentration of N in soil, it was observed a decrease of it concentration probably due to the consumption of CC in the soybean treatments. Finally, the yields of cash crops in general were not affected, except for a single year where corn production was statistically higher in the treatment without CC (between 1000 and 2000 kg ha-1). Therefore, it is necessary to adjust CC management according to climatic situations and the cash crop.Fil: Beltran, Marcelo Javier. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Suelos; ArgentinaFil: Galantini, Juan Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Tognetti, Pedro Maximiliano. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Barraco, Miriam. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Buenos Aires Norte. Estacion Experimental Agropecuaria General Villegas. Agencia de Extension Rural General Villegas.; Argentin

Global change effects on plant communities are magnified by time and the number of global change factors imposed

Komatsu, Kimberly J. Smithsonian Environmental Research Center, Edgewater. United States.Avolio, Meghan L. Johns Hopkins University. Department of Earth and Planetary Sciences. Baltimore, United States.Lemoine, Nathan P. Marquette University. Department of Biological Sciences. Milwaukee, United States.Chaneton, Enrique José. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Chaneton, Enrique José. CONICET – Universidad de Buenos Aires. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Tognetti, Pedro Maximiliano. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Tognetti, Pedro Maximiliano. CONICET – Universidad de Buenos Aires. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Yahdjian, María Laura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Yahdjian, María Laura. CONICET – Universidad de Buenos Aires. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Isbell, Forest. University of Minnesota. Department of Ecology, Evolution and Behavior. Saint Paul, United States.Grman, Emily. Eastern Michigan University. Department of Biology. Ypsilanti, United States.17867–17873Global change drivers (GCDs) are expected to alter community structure and consequently, the services that ecosystems provide. Yet, few experimental investigations have examined effects of CDs on plant community structure across multiple ecosystem types, and those that do exist present conflicting patterns. In an unprecedented global synthesis of over 100 experiments that manipulated factors linked to GCDs, we show that herbaceous plant community responses depend on experimental manipulation length and number of factors manipulated. We found that plant communities are fairly resistant to experimentally manipulated GCDs in the short term ( minor to 10 y). In contrast, long-term (major or equal to 10 y) experiments show increasing community divergence of treatments from control conditions. Surprisingly, these community responses occurred with similar frequency across the GCD types manipulated in our database. However, community responses were more common when 3 or more GCDs were simultaneously manipulated, suggesting the emergence of additive or synergistic effects of multiple drivers, particularly over long time periods. In half of the cases, GCD manipulations caused a difference in community composition without a corresponding species richness difference, indicating that species reordering or replacement is an important mechanism of community responses to GCDs and should be given greater consideration when examining consequences of GCDs for the biodiversity–ecosystem function relationship. Human activities are currently driving unparalleled global changes worldwide. Our analyses provide the most comprehensive evidence to date that these human activities may have widespread impacts on plant community composition globally, which will increase in frequency over time and be greater in areas where communities face multiple GCDs simultaneously