After studying the behavior of five dominant tree species in Mediterranean mountain areas, researchers from the National Museum of Natural Sciences (MNCN-CSIC) have verified that there is a trade-off between the survival of new specimens and the growth of existing ones. To cope with climate change, tree populations begin a demographic stabilization process in the early stages of growth.
The study, published in Perspectives in Plant Ecology, Evolution and Systematics, has focused on measuring the impact of climate change on well-established juvenile tree specimens (between two and five years old) with the potential to reach adults in Mediterranean areas of Montana.
Specifically, the scientists analyzed three species whose limit of their distribution is in these regions: Scots pine (Pinus sylvestris), black pine (Pinus uncinata) and common beech (Fagus sylvatica), and two properly Mediterranean, holm oak. (Quercus iliex) and the black pine (Pinus nigra subspecies salzmmanii).
“What we have done has been to analyze the distribution patterns, checking the abundance and measuring the growth of these juvenile specimens from 306 points distributed in different ranges of altitude in nine mountainous regions, foreseeing that before global warming the species tend to increase their range of distribution looking for cooler areas ”, contextualizes Fernando Valladares, MNCN researcher.
Asymmetric replacement of forests
Despite the notable differences between the species studied, the experts detected a similar behavior pattern in the appearance of new specimens. “We have seen that there is an asymmetric replacement of forested areas. More specimens appear in somewhat higher areas of the distribution area of each species, but the growth of new specimens is greater at lower altitudes ”, explains Valladares.
“It is a trade-off between survival and replacement with new specimens. It could be a way of counteracting in part the negative effect that global warming causes in the limits of the range of the different species ”, he continues.
Climate change is altering the geographical distribution of species in all ecosystems on the planet. Depending on the weather and the barriers they encounter, the species are redistributed by areas where they manage to survive but it is unknown where exactly they move and the magnitude of this change in their real distribution.
"Our results highlight the importance of considering the different responses of the same species in each age or demographic phase (juvenile, adult, senescent) throughout the climatic range of its distribution to understand the effects that climate change could exert on the distribution of species and population dynamics ”, concludes Valladares.
Raquel Benavidesa, R., Escuderob, A., Coll L., Ferrandis, P., Gouriveau, F., Hódare, J.A., Ogayaf. R., Rabasag, S.G., Grandag, E., Santamaría, B.P., Martínez-Vilaltaf, J., Zamorae, R., Espelta, J.M., Peñuelas, J.M. and Valladares, F. (2015) "Survival vs. growth trade-off in early recruitment challenges global warming impacts on Mediterranean mountain trees". Perspectives in Plant Ecology, Evolution and Systematics.