article id 964,
category
Research article
Highlights:
The main components affecting growth compensation in silver birch seedlings are the timing and severity of foliage damage; The ability to compensate growth is also dependent upon the limits of temperature and nutrient availability; The responses of birches imply that folivory does not necessarily lead to reduced net productivity under changing climate
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Atmospheric warming increases the abundance of insect herbivores and intensifies the risk of defoliation, especially in high latitude forests. At the same time, the effects of increasing temperature and CO2 on plant responses to foliage damage are poorly understood. We examined if previous-year defoliation, varying between 0 and 75% of total leaf area, and different combinations of elevated temperature, CO2 and nutrient availability alter the growth of two-year old silver birch (Betula pendula Roth) seedlings. We measured the greatest height growth in seedlings that were fertilized and defoliated twice at the level of 50% of total leaf area, and subjected to elevated temperature with ambient CO2. The lowest growth was recorded in unfertilized seedlings that were defoliated twice at the level of 25% of total leaf area, and grew under ambient temperature with ambient CO2. The total biomass increased in all seedlings that were fertilized or grew under elevated temperature. The root: shoot ratios were low in defoliated seedlings, or seedlings subjected to fertilization or temperature elevation. Our conclusion is that ability of birches to compensate height growth is highly dependent upon the magnitude and frequency of defoliation on the limits of temperature and nutrient availability. These responses imply that folivory does not necessarily lead to reduced net productivity of trees under changing climate.
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Huttunen,
Section of Ecology, Department of Biology, University of Turku, FI-20014 Turku, Finland
E-mail:
liisa.huttunen@utu.fi
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Ayres,
Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
E-mail:
matt.ayres@dartmouth.edu
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Niemelä,
Section of Biodiversity and Environmental Science, Department of Biology, University of Turku, FI-20014 Turku, Finland
E-mail:
pekka.niemela@utu.fi
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Heiska,
The Finnish Forest Research Institute, Punkaharju Unit, Finlandiantie 18, FI-58450 Punkaharju, Finland
E-mail:
susanne.heiska@metla.fi
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Tegelberg,
Digitarium - Digitization Centre of the Finnish Museum of Natural History and the University of Eastern Finland, Joensuu Science Park, P.O. Box 111, FI-80101 Joensuu, Finland
E-mail:
riitta.tegelberg@helsinki.fi
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Rousi,
The Finnish Forest Research Institute, Vantaa Unit, P.O. Box 18, FI-01301 Vantaa, Finland
E-mail:
matti.rousi@metla.fi
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Kellomäki,
Faculty of Science and Forestry, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
E-mail:
seppo.kellomaki@uef.fi