A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Effects of warming climate on early-season carbon allocation and height growth of defoliated mountain birches
Tekijät: Huttunen L, Blande JD, Li T, Rousi M, Klemola T
Kustantaja: SPRINGER
Julkaisuvuosi: 2013
Journal: Plant Ecology
Tietokannassa oleva lehden nimi: PLANT ECOLOGY
Lehden akronyymi: PLANT ECOL
Numero sarjassa: 3
Vuosikerta: 214
Numero: 3
Aloitussivu: 373
Lopetussivu: 383
Sivujen määrä: 11
ISSN: 1385-0237
DOI: https://doi.org/10.1007/s11258-013-0175-0
Tiivistelmä
Tree carbohydrate reserves are usually compromised following insect outbreak, which results in a delay in leaf emergence and a reduction in growth, especially in cold environments. However, in recent times, severe defoliation of subarctic mountain birches (Betula pubescens ssp. czerepanovii) by the winter moth (Operophtera brumata) has not induced such responses. This may be the result of a warming climate stimulating plant primary metabolism. We examined if increasing thermal sum (sum of daily mean temperatures above +5 A degrees C, d.d.) and complete foliage loss affected the concentrations of carbohydrates in sap, juvenile leaves, and fine roots of mountain birches in northern Finland and Norway. The sampling was conducted at the beginning of the growing season, two years after the insect outbreak. We also investigated the morphologic properties of mature leaves and the shoot growth of the trees. Our results showed that the carbohydrate concentrations in leaves and roots (averages 67.8 and 12.5 mg g(-1) DW, respectively) decreased in defoliated trees with increasing thermal sum (> 400 d.d.), whereas the response in intact trees was the opposite. The carbohydrates in the sap were unaffected by defoliation or thermal sum accumulation. The leaf area of mature leaves and the height growth of long shoots were greater in trees at warmer sites, irrespective of defoliation. However, defoliation increased the leaf weight per area (SLW: specific leaf weight). We conclude that under warmer growing conditions, low early-season leaf and fine root carbohydrate concentrations of previously defoliated trees cannot be used as indicators of aboveground growth.
Tree carbohydrate reserves are usually compromised following insect outbreak, which results in a delay in leaf emergence and a reduction in growth, especially in cold environments. However, in recent times, severe defoliation of subarctic mountain birches (Betula pubescens ssp. czerepanovii) by the winter moth (Operophtera brumata) has not induced such responses. This may be the result of a warming climate stimulating plant primary metabolism. We examined if increasing thermal sum (sum of daily mean temperatures above +5 A degrees C, d.d.) and complete foliage loss affected the concentrations of carbohydrates in sap, juvenile leaves, and fine roots of mountain birches in northern Finland and Norway. The sampling was conducted at the beginning of the growing season, two years after the insect outbreak. We also investigated the morphologic properties of mature leaves and the shoot growth of the trees. Our results showed that the carbohydrate concentrations in leaves and roots (averages 67.8 and 12.5 mg g(-1) DW, respectively) decreased in defoliated trees with increasing thermal sum (> 400 d.d.), whereas the response in intact trees was the opposite. The carbohydrates in the sap were unaffected by defoliation or thermal sum accumulation. The leaf area of mature leaves and the height growth of long shoots were greater in trees at warmer sites, irrespective of defoliation. However, defoliation increased the leaf weight per area (SLW: specific leaf weight). We conclude that under warmer growing conditions, low early-season leaf and fine root carbohydrate concentrations of previously defoliated trees cannot be used as indicators of aboveground growth.
Turun yliopiston Tutkimustietojärjestelmän portaali