Biomass allocation shifts of Fagus sylvatica L. and Pinus sylvestris L. seedlings in response to temperature / Prerazporeditev biomase pri sadikah Fagus sylvatica L. in Pinus sylvestris L. kot odziv na temperaturo

Abstract

Abstract

Since the impact of temperature on seedling growth and biomass allocation of different tree species remains relatively unknown, the influence of different temperature conditions on stem diameter (xylem and bark), stem and root extensions, as well as below- and aboveground woody biomass, in three-year old European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.) seedlings in 2010–2011 were studied. One-year-old seedlings were grown outdoors (mean temperature during the growing season = 17–19°C), in the greenhouse (mean temperature during the growing season = 22–24°C) and climatized room (mean temperature during the growing season = 15–17°C) for two years. In terms of radial increment, xylem increments were narrowest in the case of increased temperature for beech and decreased temperature for pine. There was no difference in the thickness of the bark in beech seedlings exposed to different temperature conditions whereas in pine, the bark proportion was highest in control seedlings with the widest diameters. The periderm thickness was comparable in seedlings exposed to different temperatures and represented 10–14 % and 15 % of the bark tissue in pine and beech, respectively. Comparison of the total radial increments of seedlings of the two species under different temperature conditions showed that they were wider in pine in all three regimes. Increment of the main root was considerably higher in both species and represented about 90 % of the total length increment in beech and 74–87 % in pine. In addition, woody biomass was substantially higher aboveground in both tree species (by about 70–80 %). With beech, above- and belowground biomass was reduced in the case of elevated temperature, with the smallest share of roots. In pine, lower temperature diminished amount of biomass and caused its greatest allocation to belowground, which represented almost half of the total biomass accumulation. The short-term treatments clearly show that biomass allocation shifts of pine and beech in response to temperature seem to be a species-specific. The observed differences could be viewed as a plastic adjustment to environmental heterogeneity. 

Key words: European beech, Scots pine, radial increment, stem, root, bark, xylem

Izvleček 

Malo je znanega o vplivu temperature na rast sadik in alokacijo biomase pri različnih drevesnih vrstah, zato smo raziskali vpliv različnih temperaturnih razmer na debelinsko rast debla (tj. les in skorja), vršno rast debla in korenin ter na podzemno in nadzemno lesno biomaso pri triletnih sadikah navadne bukve (Fagus sylvatica L.) in rdečega bora (Pinus sylvestris L.) v obdobju 2010–2011. V ta namen so bile enoletne sadike dve leti izpostavljene trem različnim temperaturnim režimom: na prostem (povprečna temperatura v času rastne sezone = 17–19°C), v rastlinjaku (povprečna temperatura v času rastne sezone = 22–24°C) in v hladilni komori (povprečna temperatura v času rastne sezone = 15– 17°C). Lesni prirastki so bili najmanjši v primeru povišane temperature pri bukvi, pri boru pa pri zmanjšani temperaturi. Pri sadikah bukve izpostavljenih različnim temperaturnim razmeram ni bilo razlik v širini skorje, medtem ko je bil delež skorje pri boru največji pri kontrolnih sadikah, ki so imele tudi najširše premere. Debelina periderma je bila primerljiva pri sadikah izpostavljenih različnim temperaturam in je predstavljala 10–14 % tkiva skorje pri bukvi in 15 % tkiva pri boru. Debelinski prirastki so bili v vseh režimih širši pri boru kot pri bukvi. Prirastek glavne korenine je bil znatno večji kot prirastek debla pri obeh vrstah in je predstavljal približno 90 % celotne vršne rasti pri bukvi in 74–87 % pri boru. Nadzemna lesna biomasa je bila pri obeh drevesnih vrstah bistveno večja (za približno 70–80 %) v primerjavi s podzemno biomaso. Pri bukvi je bila celotna biomasa zmanjšana pri povišani temperaturi z najmanjšim deležem korenin. Pri boru je bila najmanjša količina biomase pri znižani temperaturi, ko smo zabeležili največjo prerazporeditev biomase v podzemne dele, ki so predstavljali skoraj polovico celotne lesne biomase. Kratkoročni poskusi kažejo, da okoljske razmere za optimalno rast proučevanih drevesnih vrst niso primerljive, kar se odraža v različnih prerazporeditvah biomase pri boru in bukvi pri različnih temperaturnih režimih. 

Ključne besede: navadna bukev, rdeči bor, debelinski prirastek, deblo, korenina, skorja, les