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Abstract: Patterns of above- and below-ground biomass allocation in seedlings of nine common cloud forest (CF) tree species of western Mexico were examined under varying controlled light conditions using artificial shade houses. We analysed the relationships between vital rates (growth and survival) and four morphological traits (SLA, biomass allocation to stems, leaves and roots). We hypothesised that these traits represent differentiation axes in the way seedlings face the heterogeneous light regime typical of the CF understorey. For all species, traits between the different light levels, i.e. allocation to leaves, roots and stems differed among light levels. Five species had the largest SLA in the lowest light levels at the end of the experiment (Citharexylum, Dendropanax, Fraxinus, Quercus and Magnolia). Juglans was the only species with a large SLA at the highest light level (377.47cm2 g−1). In contrast, light levels did not cause any significant variation in SLA of Persea and Simplococarpon at the end of the experiment. The relative height growth rates (RHGR) of the seedlings of five species were significantly different between light levels (P <0.05). Overall, all species grew better in the highest light levels. The RHGR of three species were correlated positively with SLA. In turn, allocation to stem, leaves and root biomass were strongly correlated with the RHGR of five species (e.g. Citharexylum, Dendropanax and Fraxinus). Survival did not vary significantly between treatments in any species, only in the case of Simplococarpon (P <0.05) and was correlated with all morphological variables. For this species, Peto and Peto''s test showed a significantly larger survival of seedlings in the highest light level. The mean responses of these species based on all traits to the controlled light variation did not differed significantly. Our results show that these species display a wide range of resource allocation patterns when exposed to the varying light conditions that may be found in the forest understorey and highlight the role of morphological traits in this variation. [Copyright &y& Elsevier]

• Fir forest is a mono-specific forest and from late or climax successional state. • The most realistic scenarios suggest an imminent extinction of fir forests in study area. • The most important diameter size class that contributes to λ is >50 cm dbh followed for <10–20. • Matrices linked to climatic variation offer a useful tool to explore the growth of populations. The demographic traits associated to climatic variations are a useful tool for the study of the dynamics of plant populations under normal conditions, as well as in different scenarios and sequences of events, such as El Niño-Southern Oscillation. Six climatic scenarios (with and without the influence of El Niño precipitation anomaly events, among others) were built and tested. The question in this study was: What is the tendency of Abies religiosa populations in relation to different climatic events? Our hypothesis is that, under a normal frequency of climatic events, the population will decrease, and that it would increase if those events accompanied by more rain were to become more frequent. Between 2012 and 2016, three reproductive cycles of Abies religiosa were registered. With these data, transition, sensibility and variation matrices were built, and population growth rates (λ) and their confidence interval estimated. Also, simulations for population dynamics under different climatic scenarios were performed. Fir forests have an inverted J shape structure, i.e., they regenerate under their own canopy. The λ of the average matrix was 0.99, with 95% variation between 0.99 and 1.053. Most likely scenarios suggest the extinction of fir forests. Abies religiosa forms mono-specific masses and represents a late or climactic successional stage. For management and conservation purposes, the most important diameter size classes are >50 cm, followed by 10–20 cm. These are the classes that contribute the most to the λ, and the ones that present greater variation. Transition matrices associated to different simulated climatic events are a useful tool to anticipate possible impacts of climatic change on forest tree population demography. [ABSTRACT FROM AUTHOR]