In Mediterranean continental climates, trees face a double climatic stress, cold winters and dry
summers. Improved understanding of the different climate sensitivity in coexisting tree
species may help to better predict future forest dynamics in a global warming scenario. We
measured wood anatomical features as related to weekly- to monthly-resolved weather
records to determine the main climatic drivers of wood formation at intra-annual scales. Two
coexisting Mediterranean conifers (Pinus halepensis and Juniperus thurifera) were
considered to measure tree-ring width and anatomical variables (lumen transversal area and
cell-wall thickness) using the software ROXAS. We related these variables with local climatic
data (mean minimum and maximum temperatures, precipitation, soil moisture deficit) for the
period 1970-2013. Both tree-ring width and lumen area showed similar year-to-year
variability indicating common climatic signals acting on both variables. Tree-ring width
increased as previous winter precipitation did. Lumen area responded positively to wet spring
conditions, particularly in the case of the juniper. In juniper, cell-wall thickness increased
when early summer conditions became drier. These observations are consistent with the
presence of intra-annual density fluctuations (IADF) in the juniper latewood which increased
in parallel with late-summer water balance. This confirms that latewood IADFs reflect
changing water availability in the late growing season as larger tracheid lumens. The analysis
of wood anatomical traits allowed inferring long-term growth and wood-anatomical responses
to climate at intra-annual scales, which were consistent with previous observations of
xylogenesis and the different sensitivity to climate of the two coexisting conifer specie