Bogdziewicz M., Szymkowiak J., Fernández-Martínez M., Peñuelas J., Espelta J.M. (2019) The effects of local climate on the correlation between weather and seed production differ in two species with contrasting masting habit. Agricultural and Forest Meteorology. 268: 109-115.EnllaçDoi: 10.1016/j.agrformet.2019.01.016
Many plant species present inter-annual cycles of seed production (mast seeding), with synchronized high seed production across populations in some years. Weather is believed to be centrally involved in triggering masting. The links between meteorological conditions and seeding are well-recognized for some species, but in others consistent correlates have not been found. We used a spatially extensive data set of fruit production to test the hypothesis that the influence of weather on seed production is conditioned by local climate and that this influence varies between species with different life history traits. We used two model species. European beech (Fagus sylvatica) that is a flowering masting species, i.e. seed production is determined by variable flower production, and sessile oak (Quercus petraea) that is a fruit-maturation masting species, i.e. seed production is determined by variable ripening of more constant flower production. We predicted that climate should strongly modulate the relationship between meteorological cue and fruit production in Q. petraea, while the relationship should be uniform in F. sylvatica. The influence of meteorological cue on reproduction in fruiting masting species should be strongly conditioned by local climate because the strength of environmental constraint that modulates the success of flower-to-fruit transition is likely to vary with local climatic conditions. In accordance, the meteorological cuing was consistent in F. sylvatica. In contrast, in Q. petraea the relationship between spring temperature and seed production varied among sites and was stronger in populations at colder sites. The clear difference in meteorological conditioning of seed production between the two studied species suggests the responses of masting plants to weather can be potentially systematized according to their masting habit: i.e. fruiting or flowering. © 2019 Elsevier B.V.
Fernández-Martínez M., Sardans J., Chevallier F., Ciais P., Obersteiner M., Vicca S., Canadell J.G., Bastos A., Friedlingstein P., Sitch S., Piao S.L., Janssens I.A., Peñuelas J. (2019) Global trends in carbon sinks and their relationships with CO2 and temperature. Nature Climate Change. 9: 73-79.EnllaçDoi: 10.1038/s41558-018-0367-7
Elevated CO2 concentrations increase photosynthesis and, potentially, net ecosystem production (NEP), meaning a greater CO2 uptake. Climate, nutrients and ecosystem structure, however, influence the effect of increasing CO2. Here we analysed global NEP from MACC-II and Jena CarboScope atmospheric inversions and ten dynamic global vegetation models (TRENDY), using statistical models to attribute the trends in NEP to its potential drivers: CO2, climatic variables and land-use change. We found that an increased CO2 was consistently associated with an increased NEP (1995–2014). Conversely, increased temperatures were negatively associated with NEP. Using the two atmospheric inversions and TRENDY, the estimated global sensitivities for CO2 were 6.0 ± 0.1, 8.1 ± 0.3 and 3.1 ± 0.1 PgC per 100 ppm (~1 °C increase), and −0.5 ± 0.2, −0.9 ± 0.4 and −1.1 ± 0.1 PgC °C−1 for temperature. These results indicate a positive CO2 effect on terrestrial C sinks that is constrained by climate warming. © 2018, The Author(s), under exclusive licence to Springer Nature Limited.
Peñuelas J., Fernández-Martínez M., Ciais P., Jou D., Piao S., Obersteiner M., Vicca S., Janssens I.A., Sardans J. (2019) The bioelements, the elementome, and the biogeochemical niche. Ecology. 100: 0-0.EnllaçDoi: 10.1002/ecy.2652
Every living creature on Earth is made of atoms of the various bioelements that are harnessed in the construction of molecules, tissues, organisms, and communities, as we know them. Organisms need these bioelements in specific quantities and proportions to survive and grow. Distinct species have different functions and life strategies, and have therefore developed distinct structures and adopted a certain combination of metabolic and physiological processes. Each species is thus also expected to have different requirements for each bioelement. We therefore propose that a “biogeochemical niche” can be associated with the classical ecological niche of each species. We show from field data examples that a biogeochemical niche is characterized by a particular elementome defined as the content of all (or at least most) bioelements. The differences in elementome among species are a function of taxonomy and phylogenetic distance, sympatry (the bioelemental compositions should differ more among coexisting than among non-coexisting species to avoid competitive pressure), and homeostasis with a continuum between high homeostasis/low plasticity and low homeostasis/high plasticity. This proposed biogeochemical niche hypothesis has the advantage relative to other associated theoretical niche hypotheses that it can be easily characterized by actual quantification of a measurable trait: the elementome of a given organism or a community, being potentially applicable across taxa and habitats. The changes in bioelemental availability can determine genotypic selection and therefore have a feedback on ecosystem function and organization, and, at the end, become another driving factor of the evolution of life and the environment. © 2019 by the Ecological Society of America
Vergotti M.J., Fernández-Martínez M., Kefauver S.C., Janssens I.A., Peñuelas J. (2019) Weather and trade-offs between growth and reproduction regulate fruit production in European forests. Agricultural and Forest Meteorology. 279: 0-0.EnllaçDoi: 10.1016/j.agrformet.2019.107711
Some tree species have a highly variable year-to-year pattern of reproduction which has repercussions for the entire ecosystem. Links between meteorological variability, fruit production and crown cover, and trade-offs between reproduction and vegetative growth, remain elusive, despite a long history of research. We explored how meteorological conditions determined variations in fruit production and crown cover and how remotely sensed vegetation indices, such as the enhanced vegetation index (EVI), may be used to characterize the fluctuations in fruit production. We used data for fruit production from six European tree species (Abies alba, Picea abies, Pseudotsuga menziesii, Fagus sylvatica, Quercus petraea and Q. robur) growing in monospecific stands, EVI and seasonal meteorological variables (precipitation and temperature) for 2002–2010. Weather accounted for fruit production better than EVI. Deciduous trees were more responsive to weather than evergreens, most notably to different seasonal temperatures, which were positively correlated mainly with crown cover and fruit production in deciduous species. Our results also suggested different patterns of relationships between fruit production, crown cover and weather, indicating different strategies of resource management. These patterns indicated a possible internal trade-off in evergreens, with resources allocated to either growth or reproduction. In contrast, in deciduous species we found no evidence for such a trade-off between vegetative growth and reproduction. © 2019 Elsevier B.V.
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