The trade-off between cold resistance and growth determines the Nothofagus pumilio treeline

Abstract

The upper and poleward limit of tree distribution are usually determined by abiotic factors such as low temperature and strong winds. Thus, cold resistance is a key element for survival in high altitudes and latitudes where conditions can reduce plant growth. A trade-off between resource allocation to cold resistance and growth could emerge in populations frequently exposed to low temperatures like those in the treeline zone. We studied annual height growth and ice nucleation temperature in Nothofagus pumilio (Nothofagaceae) populations growing in its extremes of altitudinal distribution and in 3 sites situated on a latitudinal gradient in the Chilean Andes. Additionally, gas exchange, water and nitrogen use efficiency and total soluble sugar (TSS) were also measured as possible mechanisms for survival in high altitudes. Individuals from the treeline populations showed lower annual height growth and lower ice nucleation temperatures compared with those from lower populations. In the same way, individuals from more poleward populations showed lower annual height growth and lower ice nucleation temperatures. Gas exchange, water and nitrogen use efficiency and TSS were also higher in the high altitude populations. The results obtained support the hypothesis of trade-off, because the upper and poleward populations showed more cold resistance but a lower height growth. Additionally, we show that cold resistance mechanisms do not impact the physiological performance, suggesting possible adaptation of the high altitude populations. Low temperatures may be affecting cellular growth instead of photosynthesis, creating a pool of carbohydrates that could participate in cold tolerance. Other abiotic and biotic factors should be also assessed to fully understand the distributional range of Nothofagus species.

Seasonal Frost Tolerance of Trees in the New Zealand Treeline Ecotone

“…Phyllocladus can endure ‫61מ‬ ЊC frosts, almost 5 ЊC colder than Nothofagus, yet it barely reaches tree height in the alpine ecotone and grows as a low (Ͻ2.0 m in height), layering shrub (Wardle 1969). It is a very slow growing tree, in contrast to Nothofagus, and it is possible its high level of frost resistance comes at the price of less rapid growth (e.g., Koehler et al, 2012;Molina-Montenegro et al, 2011). Additionally, the collapse of tissue under moderate water stress, common to Podocarpaceae, may limit the success of Phyllocladus in this summer-dry alpine environment (Brodribb, 2011).…”

Experimental evaluation of the robustness of the growth–stress tolerance trade‐off within the perennial grass Dactylis glomerata

“…Consequently, the ability for a plant to survive harsh environmental conditions likely induces a cost in terms of growth capacity (Chapin, 1980;Stearns, 1989), the so-called growth-stress survival trade-off. Multiple evidences of such trade-offs were found, for example in response to shade (Inman-Narahari et al, 2014;Sack & Grubb, 2001;Sterck, Poorter, & Schieving, 2006;Walters & Reich, 1999;Wright et al, 2010), frost (Koehler, Center, & Cavender-Bares, 2012;Loehle, 1998;Molina-Montenegro, Gallardo-Cerda, Flores, & Atala, 2012;Savage & Cavender-Bares, 2013) or drought (Benavides et al, 2015;Pearson, Burslem, Goeriz, & Dalling, 2003;Volaire, Barkaoui, & Norton, 2014). However, some species may have specific strategies to cope with stress resulting in an apparent decoupling between growth and survival.…”

Competitor or facilitator? The ambiguous role of alpine grassland for the early establishment of tree seedlings at treeline

“…Competition as well as microclimatic modifications by alpine vegetation are likely to affect seedling performance via changes in carbon acquisition (photosynthesis) and use (growth, respiration, losses through biomass loss or trophic interactions). Adult trees at treeline do not appear to be limited by carbon (Hoch and Körner , Shi et al , Fajardo et al , Molina‐Montenegro et al ). Seedlings, however, differ substantially from adult trees in terms of physiology (Day et al , Tegischer et al ) and microclimate (Körner ).…”