Selective drought-induced decline of pine species in southeastern Spain

Abstract

The negative impacts of severe drought on the growth and vigor of tree species and their relationship with forest decline have not been properly evaluated taking into account the differential responses to such stress of trees, sites and species. We evaluated these responses by quantifying the changes in radial growth of plantations of four pine species (Pinus sylvestris, Pinus nigra, Pinus pinaster, Pinus halepensis) which showed distinct decline and defoliation levels in southeastern Spain. We used dendrochronological methods, defoliation records, linear mixed models of basal area increment and dynamic factor analysis to quantify the responses of trees at the species and individual scales to site conditions and drought stress. In the region a temperature rise and a decrease in spring precipitation have led to drier conditions during the late twentieth century characterized by severe droughts in the 1990s and 2000s. As expected, the defoliation levels and the reductions in basal area increment were higher in those species more vulnerable to drought-induced xylem embolism (P. sylvestris) than in those more resistant (P. halepensis). Species adapted to xeric conditions but with high growth rates, such as P. pinaster, were also vulnerable to drought-induced decline. The reduction in basal area increment and the Climatic Change (2012) 113:767-785 defoliation events occurred after consecutive severe droughts. A decrease in spring precipitation, which is the main driver of radial growth, is the most plausible cause of recent forest decline. The sharp growth reduction and widespread defoliation of the most affected pine plantations of Scots pine make their future persistence in drought-prone sites unlikely under the forecasted warmer and drier conditions.

Recent Drought-Induced Vitality Decline of Black Pine (Pinus nigra Arn.) in South-West Hungary—Is This Drought-Resistant Species under Threat by Climate Change?

“…Therefore we conducted the response-function analysis only for the present year that supported the results of correlation analysis by identifying the precipitation, the SPEI and the REW of June as the most significant (Figure 8). In general, our results correspond to other studies describing spring/summer moisture availability as the main climatic driver of Pinus nigra growth in the Mediterranean [65][66][67][68][69][70][71][72].…”

Forest Growth Responses to Drought at Short- and Long-Term Scales in Spain: Squeezing the Stress Memory from Tree Rings

“…Legacy effects tend to be more noticeable in arid or semiarid biomes such as some xeric rear-edge forests, where growth rates and productivity decrease (Sánchez-Salguero et al, 2012;Vicente-Serrano et al, 2013), compared to wet biomes and more mesic sites (Anderegg et al, 2015;Gazol and Camarero, 2016). Despite all the examples provided here show that drought always causes a marked growth reduction, the magnitude of this growth loss and the associated legacy effects differed considerably between sites.…”

“…Furthermore, multi-year droughts should be considered to evaluate this recovery capacity because they negatively impact forests at several time scales as the 1994-1995 drought did across eastern Spain (Peñuelas et al, 2001). Scots pine and black pine forests in this drought-prone region illustrate this aspect since both species experienced a marked growth reduction in response to the 1994-1995 drought (e.g., Figures 4A, 5A), and they also manifested dieback and high mortality in some regions (Sánchez-Salguero et al, 2012, 2013Camarero et al, 2015b). Forecasted warmer and drier conditions make some rear-edge Scots pine and black pine populations from eastern Spain highly vulnerable to Twenty-first-century droughts .…”

“…For instance, the 2003 heat wave mainly affected central Europe and it was characterized by abnormally warm temperatures during the growing season resulting in a substantial reduction in forest productivity (Ciais et al, 2005). Conversely, the 1994-1995 and 2005 dry spells mostly affected Mediterranean regions of south-western Europe (e.g., Spain) and they were characterized by unusually low values of precipitation that induced widespread growth decline and triggered forest dieoff (Peñuelas et al, 2001;Carnicer et al, 2011;Sánchez-Salguero et al, 2012). On the other hand, the 2012 drought mostly affected eastern and southern Spain and it was initiated by very warm and dry conditions during the previous winter and the early growing season (Camarero et al, 2015b).…”

“…For example, this is the case of some silver-fir (Abies alba) populations showing dieback in the Spanish Pyrenees due to a pronounced and long-term growth decline which started after the 1986 drought Gazol and Camarero, 2016). Ultimately, intense droughts can induce irreversible growth and vigor loss resulting in tree death (Sánchez-Salguero et al, 2012;Camarero et al, 2015b;Cailleret et al, 2017). Here we define the long-term legacy effects by selecting severe droughts representing "tipping-points" in tree vigor and triggering forest dieback (Camarero et al, 2015b).…”