Drought impacts on tree growth of two pine species along an altitudinal gradient and their use as early-warning signals of potential shifts in tree species distributions

作者：Marques Laura; Julio Camarero J; Gazol Antonio; Zavala Miguel A

来源：Forest Ecology and Management, 2016, 381: 157-167.

DOI：10.1016/j.foreco.2016.09.021

• Basal area increment
• Dendroecology
• Drought stress
• Pinus nigra subsp salzmannii
• Pinus sylvestris
• Resilience

Mediterranean pine forests are at risk of experiencing a decline in tree growth in response to climate warming if rising temperatures amplify drought stress. In mountain areas, tree growth could be enhanced in temperature-limited high elevations, whilst it might decline at water-constrained low elevations. Species differential responses could, however, modulate the impact of drought on forests along attitudinal gradients. To test for evidence of species differential drought impacts along an attitudinal gradient, we studied the growth responses of two Iberian pine species (Pinus sylvestris and Pinus nigra) subjected to Mediterranean conditions in Eastern Spain. We analysed the stability of growth (basal area increment) responses to climate and drought during the 1950-2014 period by using resistance and resilience indices. Pinus sylvestris growth was enhanced by warm spring temperatures, while Pinus nigra growth was improved by a positive spring water balance. Pinus sylvestris growth decreased temporally at the lower end of its attitudinal range, whereas Pinus nigra growth decreased at the upper end. Pinus sylvestris exhibited low growth stability at its low-elevation limit. Pinus nigra resistance also decreased along its attitudinal range, but this effect was compensated by a high resilience. In mixed stands the results were contrasting, with Pinus sylvestris (at the lower attitudinal range) being more vulnerable to drought induced growth decline than Pinus nigra (at the upper altitudinal range). Under more severe and frequent dry spells, Pinus sylvestris at low altitude may be highly vulnerable to water shortage while Pinus nigra performs better. These growth responses are in line with the expectation of a contraction in the realized niche of Pinus sylvestris with extirpation of low-elevation stands if warmer and drier conditions continue. Moreover, we show that analysing growth resilience in response to drought is a useful method to anticipate likely changes in species dominance and thus to assist managers in designing forest adaptation strategies.

• 出版日期2016-12-1