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The Mediterranean stone pine is currently on its way to domestication. Its genuine Mediterranean pine nuts are among the most expensive nuts in the world because they are mainly wild-collected from pine forests and woodlands. Despite the wide current distribution of stone pine over the whole Mediterranean biome, old-growth forests are scarce, often associated locally with dynamics on lose sands, coastal dunes or former estuary marshes. The species has been found to be genetically depauperate, putatively due to a population bottleneck in a local refugium during the Last Glacial Maximum confirmed in southern Iberia, and a possibly anthropic range expansion during Holocene. Only recently, cone harvesting and processing mechanisation have allowed for profitable pine nut production from orchard plantations. In Spain and Portugal, first elite clones have been registered for their use as grafted orchard crop.

The widespread Mediterranean Pinus pinea showed exceptionally low genetic diversity and low differentiation between traits in the adult phase. We explored the adaptation potential of seedlings from four main Iberian provenances during their regeneration phase. We assessed the variability of shoot growth, allometry, physiological traits, and phenotypic plasticity to the interactive effect of light and water environments during 8-month moderate water-stress cycle and after one-week heat wave. The effect of shade and drought was mainly orthogonal whatever the provenance. The inland La Mancha provenance showed higher shoot growth and biomass compared to the southern coastal Depresion-del-Guadalquivir provenance. Following the heat wave, La Mancha presented higher net photosynthetic rates, a lower decrease in maximal quantum efficiency of PSII, and a higher accumulated relative height growth, thus, showing an adaptive advantage. The observed differences corroborated the ecological grouping of the provenances along latitudinal and inland–coastal gradients. We confirmed the high adaptive plasticity of Pinus pinea to the unpredictable Mediterranean environment.

Insect predation on seeds of forests species during the predispersal phase is a special case of plant-pest interaction in which, while plant survival and growth is not threatened, natural regeneration can be negatively affected. In the case of seeds with a high economic value, as is the case of nuts from the Mediterranean stone pine (Pinus pinea L.), predispersal predation can also result in severe economic losses. The insect-seed relationship shows complex spatiotemporal dynamics, including patterns of dependency between fruit availability and fluctuations in insect population, occurrence of insect outbreaks, spatial contagion and masting habit. In the present study, we focus on the damage caused by a native pest, the Dioryctria mendacella Stgr. moth, to cones and seeds of P. pinea, a forest species showing a marked masting habit. We firstly identified those environmental and stand-level factors controlling the spatiotemporal pattern of damage by D. mendacella, as well as the self-regulatory effect that interannual variability in seed production could have on the population dynamics of the moth. In a second phase, we constructed a predictive phenomenological model to forecast the probability of cone damage in a given location, as well as the expected patterns of spatiotemporal spread and dispersion. Our results revealed a strong correlation between the probability of damage and crop size in a given year, pointing to a dependency between feeding resources and predator population. Additionally, the probability of damage is affected by the number of damaged cones observed in the previous year, indicating temporal contagion. Cone and seed damage is also affected by the temperature during different phases of the complex life-cycle of D. mendacella, which suggests that breakout processes are synchronized within the territory and linked to the occurrence of bumper crops and favorable climatic conditions. We detected that the level of infestation at a given location is related to site and environmental conditions, with no significant pattern of contagion/spreading from stands with high resource availability to those with low availability. Damage prediction under warmer climate scenarios reveals a counterbalance among favorable/unfavorable conditions for insect expansion and expected decline in cone production, resulting in only slight changes. © 2016 Elsevier B.V.

Context Although drought is generally considered the main environmental constraint in Mediterranean environments, the ability to acclimate to and tolerate frost in early developmental stages can be a determinant for seedling survival of many Mediterranean tree species like stone pine (Pinus pinea L.). Aims The aim of this study was to assess the impact of the developmental stage of naturally regenerated stone pine individuals on tolerance to low temperature (LT) from summer to late autumn and in spring, at a highly continental site in central Spain. Specifically, we tested to what extent the differences in tolerance are related to shoot heteroblasty. Methods We assessed LT tolerance of needles from individuals at three age classes (class C1 seedlings, class C2 4- to 8-year-old saplings and class C3 >9-year-old saplings) over nine dates from summer to spring. Results LT tolerance displayed severe seasonal trends and differed between age classes. It usually increased with sapling age. Such differences were tightly related to heteroblasty of the shoots. Our results point to a higher LT tolerance associated with larger leaf dry mass per unit area (LMA) values. No impact of late frosts on shoot growth rates was detected during this study. Conclusions: Developmental changes during early plant growth seem to play a role in frost tolerance of stone pine seedlings, a finding which furthers our understanding of regeneration dynamics in this species in areas with continental influence. © 2014 INRA and Springer-Verlag France.