Contrasting climate influences on Nothofagus pumilio establishment along elevational gradients

ASCHERO, V.; SRUR, A. M.; GUERRIDO, C.; VILLALBA, R.

PLANT ECOLOGY

SPRINGER

Lugar: Berlin; Año: 2022 vol. 223 p. 369 - 380

1385-0237

Predicted warmer temperatures and more frequent extreme climaticevents in the southern Andes may affect the dynamics of thePatagonian forests. These environmental changes may differentiallyalter the probability of Nothofagus pumilio establishment across itsaltitudinal range of distribution. We monitored fruit fall, seedlingemergence and survival at altitudinal distribution range of N.Pumilio forests in Santa Cruz (49°22 0 S?72°56 0 W), Argentina.Fruit fall, seedling emergence and survival were tested in relationto drought, based on the SPEI (Standardized PrecipitationEvapotranspiration Index), interacting with elevation. Fruit fall wasconsistently higher at low elevation and the abundance of fruits wasnot affected by drought intensity. Density of new-born seedlings was* 9 to 24 times lower at low- than at high-elevation plots in ourfirst observations (2014 and 2016), characterized by warm-dryclimatic conditions in spring-early summers. In contrast, seedlingabundance was * 1.5 times larger at low elevations during relativelycold-wet growing seasons. Survival probability was explained by theinteraction between SPEI and elevation. At low elevation and in dryperiods, survival probability was lower (CI 54?72%) than in wetperiods (CI 68?84%) but at high elevation similar survival wasregistered even with positive or negative SPEI values. Our resultsshow interacting effects of elevation and drought on treeestablishment at the elevation limits, with positive and negativedrought effects at high and low elevations, respectively. Predictedincrease of extreme drought events during the XXI century could bedetrimental for N. pumilio establishment at dry, low-elevationforests.p { margin-bottom: 0.25cm; line-height: 115%; background: transparent }