How to cope with drought and not die trying: Drought acclimation across tree species with contrasting niche breadth

Abstract

1. Worldwide drought events have been reported to cause tree growth decline and mortality, thus altering the carbon (C) balance of forest ecosystems. While most of the attention has been focused on the physiological mechanisms associated with drought-induced tree responses of a few species at specific locations, the ecological attributes of these species, like their niche breadth, may be also important in determining species' sensitivity or resilience to drought. We postulated that wideniche breadth tree species should be more drought-resilient than narrow-niche breadth species. 2. Using the most severe 2015-2016 El Niño drought event in the last 70 years in Patagonia, we determined pre-and post-drought growth (BAI, basal area increment), C reserves in the form of non-structural carbohydrate concentrations (NSCs = starch and soluble sugars), wood isotope (δ 13 C, iWUE and δ 18 O) signalling and xylem anatomy (mean vessel diameter, mvd) in eight angiosperm tree species of contrasting niche breadth across a sharp precipitation gradient in southern Chile.3. All species responded in unison after the drought with a non-water-conservative response, maintaining BAI and NSCs, decreasing δ 13 C, and increasing both mvd and the soluble sugars:NSCs ratio relative to pre-drought time. Contrary to previous results reporting species-specific drought responses, our results show unequivocally a functional coordination of organisms' vital traits associated with a

The intraspecific relationship between wood density, vessel diameter and other traits across environmental gradients

“…Nonetheless, in this study, at the intraspecific level, we found no support for this explanation. Furthermore, we did not find that high WD was associated with high concentrations of soluble sugars, although it has been suggested that they are capable of dealing with osmotic-demanding processes like drought-induced cavitation; for example, across several tree species, starch concentration has shown decreases and soluble sugar concentration increases under slight-tomoderate drought (Fajardo & Piper, 2021;He et al, 2020). Soluble sugars have also been hypothesised to maintain their vascular integrity in dry climates (Brodersen & McElrone, 2013;Sala et al, 2012); in addition, they have been shown to be important for post-drought recovery in saplings and adult trees of Fitzroya cupressoides (Urrutia-Jalabert et al, 2020) in temperate forests, as well as in several Mediterranean species (Lloret et al, 2018).…”

“…Most of wood anatomy, leaf and chemical traits changed across gradients as well (Table 2; Table S2). These particular trait-gradient results were reported and discussed in previous studies (Fajardo & Piper, 2021;García-Cervigón et al, 2018;García-Cervigón et al, 2020) and they will not be covered in this study unless they help to explain WD-other traits relationships.…”

“…This tree species grows across a temperature‐mediated elevational gradient, from treeline elevation where trees seldom surpass 3 m in height and the mean growing season temperature is about 6.5°C down to lower elevations where trees can reach 30 m in height (Fajardo et al, 2019; Fajardo & Piper, 2014). Embothrium coccineum and N. antarctica prevail across a sharp precipitation gradient from locations with >3,000 mm of annual precipitation on the west side of the austral Andes to locations where it rains 500 mm at the east of the Andes (Fajardo & Piper, 2021; García‐Cervigón et al, 2018).…”

Species- and Age-Specific Growth Reactions to Extreme Droughts of the Keystone Tree Species across Forest-Steppe and Sub-Taiga Habitats of South Siberia

“…Forest ecosystems are constantly facing changing environmental and climatic conditions, but it is becoming obvious that they are becoming greatly affected by more frequent and prolonged droughts [1][2][3]. Over the coming decades, climate change will accelerate tree dieback due to severe drought and heat stress in many areas [4][5][6][7], especially in semiarid regions where significant decreases in forest productivity and growth stability are expected [8][9][10][11][12]. The sensitivity of trees to drought should be assessed within ecological gradients (natural zones), since the expected climate change effects depend much on the local habitat conditions [13,14].…”

“…The response of trees to climatic variables can be significantly modified by topography and soil features, species characteristics, and even individual genetic factors [18][19][20][21][22]. Clearly, species-specific modulation of climate response may be associated with their physiological strategies of coping with stress [23,24], although abiotic factors acting at the community level may cause similar responses [7]. The resilience of forest growth to extreme events, including droughts, also depends not only on the intensity and duration of stress, but also on the forest stand structure [25,26].…”