%0 Research article
%T Interactive effects of defoliation and climate change on compensatory growth of silver birch seedlings
%A Huttunen, Liisa
%A Ayres, Matthew P.
%A Niemelä, Pekka
%A Heiska, Susanne
%A Tegelberg, Riitta
%A Rousi, Matti
%A Kellomäki, Seppo
%D 2013
%J Silva Fennica
%V 47
%N 3
%R doi:10.14214/sf.964
%U https://silvafennica.fi/article/964
%X 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 CO<sub>2</sub> 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, CO<sub>2</sub> and nutrient availability alter the growth of two-year old silver birch (<em>Betula pendula</em> 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 CO<sub>2</sub>. 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 CO<sub>2</sub>. 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.<br />