Papers by Javier Sanguinetti
Austral Ecology, Apr 11, 2017
A simultaneous masting of two abundant species in the temperate forests of NorthWest Argentinean ... more A simultaneous masting of two abundant species in the temperate forests of NorthWest Argentinean Patagonia occurred in 2013 for the first time ever recorded: the semelparous bamboo grass Chusquea culeou (colihue), dominating the understory, flowered and set seed across 1100 km 2 while pehu en (Araucaria araucana), an endemic conifer co-dominating the tree layer had the highest regionally synchronized mast event in the last 30 years. Strong trophic effects were expected as a consequence of this extraordinary amount of seed, such as rodent outbreaks (ratadas) that followed previous Chusquea spp. mast events and included Oligoryzomys longicaudatus, the main reservoir of the Andes virus causing the Hantavirus Pulmonar Syndrome. From March 2013 to May 2014, we sampled relative abundance and activity of seed-eaters and carnivores at four study sites with different proportions of both masting species. Surprisingly, total rodent capture rates never exceeded 14% in wild habitats and 8% in peridomestic areas showing low overall density in spite of some heavy O. longicaudatus males extending their reproductive activity into winter. Total abundance and relative proportion of granivorous birds peaked at the four sites in winter or spring, when they are usually scarce. Other surveyed organisms (native and exotic seed-eaters, ungulates and carnivores) showed moderate responses at most, probably through aggregation from surrounding areas rather than reproduction. Seed removal from experimental seed stations varied in time and space though never peaked. The clearest pattern of community responses, though much subtler than expected, occurred at the site where colihue was abundant and pehu en scarce. This is the first systematic study that reports such a simultaneous double masting and our surveys revealed no widespread community consequences. We propose that either contingent events, such as an unprecedented drought, or permanent environmental features or contextual characteristics may explain the lack of a rodent outbreak in this area.
Galemys: Boletín informativo de la Sociedad Española para la conservación y estudio de los mamíferos, 2009
Wild boar (Sus scrofa) from Siberia were introduced into Patagonia (Argentina) between 1904 and t... more Wild boar (Sus scrofa) from Siberia were introduced into Patagonia (Argentina) between 1904 and the 1920s. Wild boar were first observed in the Lanín National Park in the 1980s. Their invasion pattern follows rivers and lakes, moving vertically from the original release site in the eastern steppes to the western hillsides. During the last 20 years, the area occupied by wild boar has increased throughout the park from 10% in 1985 to nearly 30% two decades later, mainly in Araucaria-Nothofagus forests and scrubland. These landscapes hold 83% of the current wild boar distribution, with a statistically significant threefold increase (Sr = 0.891, p<0.01). Pine plantations, grassland-steppe and bare ground are less favoured by the species, with only a twofold increase or less during the last two decades. Its distribution range has increased to over 70000 ha during the last 20 years, with an average increase of about 3500 ha/y. At this rate, the species would need 50-60 years to cover the entire Lanín National Park, but cold winters, years with poor Araucaria-Nothofagus seed production, increasing predation by puma (Puma concolor), and the possible appearance of new parasites and diseases as the population increases could limit wild boar dispersal to a lower rate.
Austral Ecology, Jun 29, 2016
Coarse woody debris (CWD) is an important element driving ecological processes, strengthening eco... more Coarse woody debris (CWD) is an important element driving ecological processes, strengthening ecosystem resilience and for biodiversity within forest ecosystems. However, the abundance and distribution of CWD and their relation to natural and human factors are poorly known in southern South America. In this work we studied the density and volume of CWD types in Nothofagus-Araucaria stands in northern Patagonia (Neuqu en-Argentina) and relationships with forest composition and structure. We also studied their relationships with fire history, topography and human-related variables. Twenty-three stands with Nothofagus pumilio, Nothofagus antarctica and/or Araucaria araucana were sampled to estimate quantities of logs, snags and dead branches using the planar-intersect method. CWD density and volume in these forests were moderate and varied across the landscape with a spatial pattern determined by biotic, abiotic and human use-related variables. Mean CWD volume was 52.9 m 3 ha À1 (range: 1.6-143.7) and significantly varied among forest types and watersheds. CWD was positively related to dbh, tree height and slope, but negatively related to tree density. CWD was clearly influenced by composition and structural characteristics of stands, where the tree species traits had an important role. As well, the observed amount and type of CWD, whereby most of the stands showed low levels of old (pre-disturbance) logs/snags and poor new inputs of deadwood, may be explained by fire frequency. Firewood gathering and livestock grazing negatively affected deadwood stocks and topography counteracts this effect by limiting human access. Fire disturbance history, windthrow and dieback pulses produced by insect outbreaks and human access seemed to be the main causes that best explained CWD spatial distribution and abundance patterns in northwestern Patagonian forests.
Mastozoología neotropical, Dec 1, 2016
Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto
Mastozoología neotropical, Dec 1, 2016
Revista Chilena de Historia Natural, 2009
El establecimiento de plántulas puede estar limitado por la producción de semillas y asociada a l... more El establecimiento de plántulas puede estar limitado por la producción de semillas y asociada a la producción intermitente y sincronizada de semillas (masting) y/o por granivoría, o por falta de micrositios aptos para la germinación y crecimiento de las plantas. La dispersión y supervivencia de semillas desde el árbol madre pueden determinar el patrón espacial del establecimiento y la literatura propone varios modelos de distancia madre-plántula. En este trabajo se estudiaron los efectos del masting, de la depredación de semillas y de la vegetación sobre el establecimiento en A. araucana. A partir de datos sobre producción de conos, sobre supervivencia de semillas y mediante el registro de plántulas a escala del árbol en distintos micrositios se evaluó el patrón temporal y espacial del establecimiento. A. araucana presentaría un establecimiento en forma de pulsos, sincronizados entre árboles, y asociado al masting debido a un significativo aumento en la supervivencia de semillas. En micrositios densos, especialmente de bambúes, la regeneración se encuentra fuertemente inhibida por la excesiva depredación de semillas y no debido a competencia con los bambúes. El patrón distancia madre-plántula observado parecería ajustarse al modelo Janzen-Connell considerando el aumento de supervivencia de semillas con la distancia y el pico de establecimiento alejado del árbol madre. Sin embargo, se detectó una significativa diferencia en el patrón distancia madre-planta entre la regeneración joven y avanzada por lo cual habría luego del establecimiento otro patrón de mortalidad edad y distancia dependientes. Los resultados sugieren que la ocurrencia de regeneración en A. araucana se encontraría controlada por la producción de semillas mientras que la granivoría, y su interacción con la vegetación, modularían la intensidad del establecimiento.
Revista Chilena de Historia Natural, Sep 1, 2008
Pre-dispersal seed predation by Austral parakeets, Enicognathus ferrugineus, on pehuén, Araucaria... more Pre-dispersal seed predation by Austral parakeets, Enicognathus ferrugineus, on pehuén, Araucaria araucana, was studied to assess the relationship between predation and seed production. We collected falling seeds in four araucaria forests of southwestern Neuquén Province, Argentina during four years that included both mast and intermast years. Predation rates were negatively correlated with seed production. When seed production was high, predation rates ranged from 0.6 to 3.3 %; when it was low, predation rates ranged from 13.0 to 20.6 %. Years differed in the pattern of monthly seed fall with peak seed fall in March 2002 and April 2003. Predation rates were lower and more uniform in the year of higher seed production, but did not differ between sites. In an intermast year, predation rates increased during the season, reaching their highest rates after peak seed fall. Parakeets handled seeds differently in mast and intermast years, dropping fewer slightly-damaged seeds when production was low. We discuss these results in the context of the predator satiation hypothesis.
Oryx, Sep 25, 2009
The American mink Mustela vison has spread widely beyond its native North American range and is a... more The American mink Mustela vison has spread widely beyond its native North American range and is associated with problems for the conservation of native species because of its impact as both predator and competitor. We investigated the impact of feral mink on waterfowl in Lanín National Park, southwest Neuquén, Patagonia, Argentina, an area in which the predator is currently expanding. Statistically significant differences were observed in the number of waterfowl species at lakes without mink (7.3-SE 0.7) compared to those with mink (4.0-SE 0.6). Overall abundance of birds observed per day was higher at lakes without (104.2-SE 20.6) than with mink (21.2-SE 22.3). The great grebe Podiceps major, speckled teal Anas flavirostris, Chiloe wigeon Anas sibilatrix and red-gartered coot Fulica armillata were more abundant on water bodies without mink, and flocks of the ashy-headed goose Chloephaga poliocephala were larger in areas without mink. Other species, such as the white-tufted grebe Rollandia rolland, coscoroba swan Coscoroba coscoroba, black-necked swan Cygnus melanocoryphus, cinnamon teal Anas cyanoptera, Andean duck Oxyura jamaicensis and Andean gull Larus serranus were never observed in areas harbouring mink. We conclude that at least 12 of the 25 waterfowl species observed are sensitive to the presence of the mink, either being absent or having a lower abundance where mink are present.
Austral Ecology, Jan 6, 2008
Masting, the intermittent and synchronous production of large seed crops, may result from eithe... more Masting, the intermittent and synchronous production of large seed crops, may result from either of two major processes: resource matching and economy of scale. Components of cone production in Araucaria araucana were partitioned among populations and trees to ascertain the existence of masting and the processes involved. Cone production data from seven populations were obtained during a 9‐year period and seed gathering data were available for an 18‐year time series from six sites in an area of more than 7600 km2. Araucaria araucana showed environmentally triggered, intermittent, moderately fluctuating, and highly regionally synchronous reproduction. The mean pairwise correlations of cones production among populations and seed gathering sites were 0.89 and 0.74, respectively, suggesting synchrony in reproduction. Among trees we observed a mean correlation of 0.74 with values ranging from 0.66 to 0.81 for the analysed populations. The existence of negative autocorrelation in seed production between year 0 and year −2 at the individual tree level suggests the presence of ‘switching’ or internal resource allocation, thus discarding the Resource Matching hypothesis. Mean coefficient of variation (CVp) among populations was moderate (0.95) and similar to the modal CVp values reported in the published reports. Mean CVi among individual trees was 1.16, suggesting a large number of equally and synchronously fluctuating trees, rather than a few largely fluctuating individuals. These results suggest that pollination efficiency and/or predator satiation hypotheses could be responsible for the masting cycles in this conifer. Ancillary data about limitation of airborne pollen dispersion and temporal variation in the amount of seeds per cone and about seed predator satiation, also support both proposed mechanisms.
University of California Press eBooks, Jul 31, 2007
... AL FLORECIMIENTO DE BAMBU (CHUSQUEA CULEOU) EN EL SUROESTE DE LA ARGENTINA Richard D. Sage, O... more ... AL FLORECIMIENTO DE BAMBU (CHUSQUEA CULEOU) EN EL SUROESTE DE LA ARGENTINA Richard D. Sage, Oliver P. Pearson1, Javier Sanguinetti, and ... of trap success were based only on results from live traps (7.5 x 9 x 22.5 cm, Model LFA, HB Sherman Traps, Inc ...
Nature plants, Jun 29, 2023
Biological Invasions, May 10, 2009
Post-dispersal seed predation can severely limit plant recruitment, but its ultimate impact could... more Post-dispersal seed predation can severely limit plant recruitment, but its ultimate impact could be modulated by environmental factors and by the composition of the granivore guild. Here, we analyze the relative impact of the non-native wild boar and native rodents on seed survival and seedling establishment of the mast conifer Araucaria araucana. Predation, seed survival and seedling establishment were measured
Ecología austral, Dec 1, 2014
RESUMEN. Los estudios sobre producción de semillas en especies arbóreas son importantes para la c... more RESUMEN. Los estudios sobre producción de semillas en especies arbóreas son importantes para la ciencia y para el manejo de los bosques nativos. En este trabajo se estudió la producción a largo plazo de conos de araucaria (Araucaria araucana), cuyas semillas son utilizadas como alimento por el ser humano, en poblaciones ubicadas en distinta exposición y altitud, y con diferente composición y estructura forestal. Se contaron conos en siete poblaciones del Parque Nacional Lanín (Neuquén, Argentina) durante 15 años (2000 a 2014), y se estimó la cantidad de conos y semillas por árbol, por hectárea y por población.
DOAJ (DOAJ: Directory of Open Access Journals), 2009
Bosque (Valdivia)
The forest of Araucaria araucana ("pewen" in Mapuche language), with its associated species of th... more The forest of Araucaria araucana ("pewen" in Mapuche language), with its associated species of the genus Nothofagus, is unique from an evolutionary, biological and sociocultural point of view. Due to the interdependence and interrelation with the Mapuche-Pewenche people, it is considered a biocultural ecosystem. This work is a comprehensive binational review of current scientific information applicable to its management and conservation. The scientific community contributed with significant advances in the knowledge of: a) the interrelationships within and significance of this biocultural ecosystem; b) the regional genetic diversity; c) the fire regimen, its main drivers, its role in forest dynamics, and the recovery capacity of biodiversity in the face of different burn severities; d) the ecological role of seed production and its unusual interactions with granivorous fauna and cavity nesters; e) the decline and death of the canopy, due to environmental stress and the emergence of new pewen pathogens; f) the consequences of the invasion of pines and exotic mammals that alter the biological interactions and the original ecological processes, and g) the effects of cattle ranching and overexploitation of firewood and pine nuts on ecological integrity and biodiversity. This knowledge is considered essential to strengthen policies and strategies for protection, conservation, and management of this ecosystem, which is endemic, rare, regionally threatened, and globally declared endangered. Considering the identified problems, it is imperative to achieve social empowerment of the Mapuche-Pehuenche people, intercultural respect, and enforcing public policies for the conservation and sustainable use of these forests.
Nature plants, Dec 14, 2021
Climate forcings determine the episodic occurrence of local climate anomalies that trigger the oc... more Climate forcings determine the episodic occurrence of local climate anomalies that trigger the occurrence of masting events (massive, synchronized and intermittent seed production by perennial plants). This suggests some kind of phase-locking of the reproductive cycles of individual plants to the climatological cycle, thus further reinforcing reproductive synchrony and the Moran effect. We propose a dendrochronological approach to filter out the long-term direct effects of climate on tree radial growth and temporal reproductive effort by sex by using actual trees as climatic controls to reconstruct masting events in Araucaria araucana , a long-lived dioecious masting conifer. In this way, we developed a multi-century-long tree masting reconstruction for South America using female–male radial growth determined by differences in timing and magnitude of the reproductive effort between sexes. We provide evidence for a regional synchronizing mechanism of masting which is drought induced by strong cold La Niña phases of El Niño/Southern Oscillation (ENSO) amplified by the positive phases of the Southern Annular Mode (SAM) that activate both female and male cone bud formation during year −2 before seed fall; that is, a long-term phase-locking between the ENSO cycle and the reproductive cycle modulated by the strength of SAM. In addition, our regional index of masting frequency showed its maximum during the late twentieth century relative to the previous centuries, suggesting that the species is currently at its maximum masting frequency concurrent with a period of enhanced temperature and drought conditions in Patagonia, probably driven by the positive phase of the SAM. This study establishes the effect of ENSO cycles modulated by SAM in South America on a native conifer over multiple centuries and the reproductive cycle of individual plants on a regional scale in line with climate events.
Ecology Letters
Increasing evidence points to intense species competition in wet tropical forests that that may b... more Increasing evidence points to intense species competition in wet tropical forests that that may be explained by interactions involving seeds, seedlings, and their consumers. Lack of tree fecundity data across temperate to tropical communities precludes analysis of how the seed resource contributes to biotic interactions that can drive biogeographic diversity patterns. A global synthesis of raw seed-production data shows a 2.4 order of magnitude increase in seed abundance from cold, dry to warm, wet climates, driven by a 2.0 order of magnitude increase in seed production for a given tree size. The modest increase in forest productivity across the same climate gradient cannot explain this 100-fold increase in seed production or the 250-fold increase in seed mass per forest area reported here. The increase in seeds per tree can arise from adaptive evolution driven by intense species interactions or from the direct effects of a warm, moist climate on tree fecundity. Either way, the massive differences in seed supply to temperate versus tropical communities ramifies through food webs, affecting community and ecosystem dynamics, including seedling competition, populations of seed consumers and frugivore-seed dispersers, all of which appear to be especially important in the wet tropics.
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Papers by Javier Sanguinetti