Climate increases regional tree‐growth variability in Iberian pine forests

Abstract

Tree populations located at the geographical distribution limit of the species may provide valuable information about tree-growth response to changes on climatic conditions. We established nine Pinus nigra, 12 P. sylvestris and 17 P. uncinata tree-ring width chronologies along the eastern and northern Iberian Peninsula, where these species are found at the edge of their natural range. Tree-growth variability was analyzed using principal component analysis (PCA) for the period 1885-1992. Despite the diversity of species, habitats and climatic regimes, a common macroclimatic signal expressed by the first principal component (PC1) was found. Moreover, considering the PC1 scores as a regional chronology, significant relations were established with Spanish meteorological data. The shared variance held by the tree chronologies, the frequency of narrow rings and the interannual growth variability (sensitivity) increased markedly during the studied period. This shows an enhancement of growth synchrony among forests indicating that climate might have become more limiting to growth. Noticeably, an upward abrupt shift in common variability at the end of the first half of the 20th century was detected. On the other hand, moving-interval response functions showed a change in the growth-climate relationships during the same period. The relationship between growth and late summer/autumn temperatures of the year before growth (AugustSeptember, negative correlation, and November, positive correlation) became stronger. Hence, water stress increase during late summer previous to tree growth could be linked to the larger growth synchrony among sites, suggesting that climate was driving the growth pattern changes. This agrees with the upward trend in temperature observed in these months. Moreover, the higher occurrence of extreme years and the sensitivity increase in the second half of the 20th century were in agreement with an increment in precipitation variability during the growing period. Precipitation variability was positively related to tree-growth variability, but negatively to radial growth. In conclusion, a change in tree-growth pattern and in the climatic response of the studied forests was detected since the mid-20th century and linked to an increase in water stress. These temporal trends were in agreement with the observed increase in warmer conditions and in precipitation variability.

Black pine (Pinus nigra Arn.) growth divergence along a latitudinal gradient in Western Mediterranean mountains

“…The increasing negative (positive) relationship with the mean temperature of spring-summer months (autumn to spring precipitation) (Fig. 7) suggests that moisture stress has increased in all regions, in accordance with results for most of the Mediterranean (Andreu et al, 2007;Macias et al, 2006;Piovesan et al, 2008) and parts of North America (Biondi, 2000). The significant upward trend of the mean sensitivity of tree-ring chronologies (Fig.…”

“…In the Iberian Peninsula, black pine is distributed along the eastern mountain ranges and covers a wide latitudinal gradient. These forests have been greatly affected by climate change during the second half of 20th century (Andreu et al, 2007). These facts place black pine in an intermediate position between boreal locations, in which mainly positive growth trends have been detected (Martínez-Vilalta et al, 2008), and more xeric pines, where negative trends dominate (Sarris et al, 2007).…”

Height increment of hybrid aspen <i>Populus tremuloides</i> x <i>P. tremula</i> as a function of weather conditions in central part of Latvia

“…Although this is usual in arid regions (i.e. Mediterranean region) (Rozas 2001;Andreu et al 2007), similar effects have recently been observed also for trees growing in boreal regions (Wilmking et al 2004). Thus, knowledge on climate growth relationships, considering regional variability (Andreu et al 2007), is necessary.…”

Rank reversals in tree growth along tree size, competition and climatic gradients for four forest canopy dominant species in Central Spain

“…Andreu et al, 2007;Cherubini et al, 2003) and physiological mechanisms linked to tree growth (e.g. Montgomery, 2004;Pereira, 1994) the causes and community-level consequences of interspecific variation in tree growth remain poorly understood, even for many canopy dominant species.…”