Suchergebnisse

10 páginas.-- 4 tablas.-- 60 referencias.-- Supporting InformationAdditional Supporting Information may be found in the online version of this article ; 1. Understanding the proximate factors that govern the widespread mast-seeding process is a question of considerable interest that remains poorly understood. The identity and effect of these factors may vary among coexisting species that differ in leaf habit, potentially resulting in temporally asynchronous patterns of seed production. 2. In this study, we aim to identify the proximate causes of mast-seeding using two oak species with contrasting leaf habit that coexist in southern Spain, the deciduous Quercus canariensis and the evergreen Q. suber. Simultaneously, we review the literature on environmental drivers of mast-seeding in Mediterranean oaks, distinguishing between evergreen and deciduous species. 3. Our results indicate that Mediterranean oaks are primarily sensitive to weather, mast-seeding being strongly correlated with water availability and air temperature, mainly in the spring and summer. 4. The two study oak species were affected by weather in quite different ways, most likely because of different abiotic requirements as well as contrasting functional strategies of resource use and biomass allocation. Specifically, annual seed production in Q. canariensis was more severely limited by drought than in Q. suber, but responded positively to warmer spring temperatures. 5. Q. canariensis showed a large interannual variability, whereas Q. suber exhibited much more constant seed production. These two species also exhibited a very low level of synchrony in their temporal patterns of seed crop size, most likely due to phenological differences in the processes of flowering and seed maturation. 6. Synthesis. Our results indicate that weather plays a crucial role as a proximate driver of mastseeding in Mediterranean oaks. We hypothesize that the current abundance of co-occurring species that differ in leaf habit could be altered under future climate change scenarios. The decline of seed production with drier conditions will be potentially greater in deciduous species, particularly those inhabiting wetter sites. Alternatively, the expected warmer temperatures could negatively affect evergreen species as a consequence of their more conservative strategy of biomass allocation. Our findings suggest that understanding how species with different functional or phenological attributes adjust their reproductive abilities to weather may enable us to infer the effects of ongoing environmental changes on population recruitment and dynamics. ; We thank the "Consejería de Medio Ambiente" (Andalusian Government) and the technical staff of Los Alcornocales Natural Park, for the facilities and support to carry out our fieldwork. We are very grateful to María Amían, Ana Pozuelos, Rocío Sánchez and other undergraduate students for field assistance. This study was supported by a postdoctoral contract of the Andalusian Government to IMPR, by the Spanish MEC projects Heteromed (REN2002- 4041-C02-02), Dinamed (CGL2005-5830-C03-01) and Interbos (CGL2008-04503-C03-01), and by the Andalusian Anasinque-PE2010-RNM-5782 project. WDK was supported by the National Science Foundation (grant DEB-0816691). ; Peer reviewed

13 páginas.-- 2 figuras.-- 7 tablas.-- 47 referencias.-- Additional supporting information may be found in the online version of this article at http://onlinelibrary.wiley.com/doi/10.1002/ecy.1490/suppinfo.-- Koenig_et_al ; Although the functional basis of variable and synchronous seed production (masting behavior) has been extensively investigated, only recently has attention been focused on the proximate mechanisms driving this phenomenon. We analyzed the relationship between weather and acorn production in 15 species of oaks (genus Quercus) from three geographic regions on two continents, with the goals of determining the extent to which similar sets of weather factors affect masting behavior across species and to explore the ecological basis for the similarities detected. Lag-1 temporal autocorrelations were predominantly negative, supporting the hypothesis that stored resources play a role in masting behavior across this genus, and we were able to determine environmental variables correlating with acorn production in all but one of the species. Standard weather variables outperformed "differential-cue" variables based on the difference between successive years in a majority of species, which is consistent with the hypothesis that weather is linked directly to the proximate mechanism driving seed production and that masting in these species is likely to be sensitive to climate change. Based on the correlations between weather variables and acorn production, cluster analysis failed to generate any obvious groups of species corresponding to phylogeny or life-history. Discriminant function analyses, however, were able to identify the phylogenetic section to which the species belonged and, controlling for phylogeny, the length of time species required to mature acorns, whether they were evergreen or deciduous, and, to a lesser extent, the geographic region to which they are endemic. These results indicate that similar proximate mechanisms are driving acorn production in these species of oaks, that the environmental factors driving seed production in oaks are to some extent phylogenetically conserved, and that the shared mechanisms driving acorn production result in some degree of synchrony among coexisting species in a way that potentially enhances predator satiation, at least when they have acorns requiring the same length of time to mature. ; This study was supported by National Science Foundation grant DEB- 1256394; Andalusian projects Anasinque- PE2010- RNM- 5782, P07- RNM02688, and P10- AGR6501; Spanish MEC projects Heteromed REN2002- 4041- C02- 02, Dinamed CGL2005- 5830- C03- 01, and Interbos CGL2008- 04503- C03- 01; a postdoctoral contract of the Andalusian Government (to IMPR); and a post-doctoral contract of the Operative Program of the European Social Fund (to MDC). ; Peer reviewed

18 páginas.-- 4 figuras.-- 1 tabla.-- 52 referencias.-- Material Suplementario http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0115371#s6 ; ©2014 Perez-Ramos et al. Mast-seeding species exhibit not only a large inter-annual variability in seed production but also considerable variability among individuals within the same year. However, very little is known about the causes and consequences for population dynamics of this potentially large between-individual variability. Here, we quantified seed production over ten consecutive years in two Mediterranean oak species - the deciduous Quercus canariensis and the evergreen Q. suber - that coexist in forests of southern Spain. First, we calibrated likelihood models to identify which abiotic and biotic variables best explain the magnitude (hereafter seed productivity) and temporal variation of seed production at the individual level (hereafter CVi), and infer whether reproductive effort results from the available soil resources for the plant or is primarily determined by selectively favoured strategies. Second, we explored the contribution of between-individual variability in seed production as a potential mechanism of satiation for predispersal seed predators. We found that Q. canariensis trees inhabiting moister and more fertile soils were more productive than those growing in more resource-limited sites. Regarding temporal variation, individuals of the two studied oak species inhabiting these resource-rich environments also exhibited larger values of CVi. Interestingly, we detected a satiating effect on granivorous insects at the tree level in Q. suber, which was evident in those years where between-individual variability in acorn production was higher. These findings suggest that individual seed production (both in terms of seed productivity and inter-annual variability) is strongly dependent on soil resource heterogeneity (at least for one of the two studied oak species) with potential repercussions for recruitment and population dynamics. However, other external factors (such as soil heterogeneity in pathogen abundance) or certain inherent characteristics of the tree might be also involved in this process. ; This study was supported by a postdoctoral contract of the Andalusian Government to IMPR, by the Spanish MEC projects Heteromed (REN2002-4041-C02-02), Dinamed (CGL2005-5830-C03-01), Interbos (CGL2008-04503-C03-01) and Diverbos (CGL2011-30285-C02), by the Andalusian Anasinque-PE2010-RNM-5782 project and the European FEDER funds. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript ; Peer Reviewed