caa a22 4500 388092785 CHVBK 20180307125256.0 cr unu---uuuuu 161130e199908 xx s 000 0 eng 10.4039/Ent131455-4 doi S0008347X00010075 pii (NATIONALLICENCE)cambridge-10.4039/Ent131455-4 Lyytikäinen-Saarenmaa Päivi Finnish Forest Research Institute, Vantaa Research Centre, PO Box 18, FIN-01301 Vantaa, Finland GROWTH RESPONSES OF SCOTS PINE (PINACEAE) TO ARTIFICIAL AND SAWFLY (HYMENOPTERA: DIPRIONIDAE) DEFOLIATION [Elektronische Daten] [Päivi Lyytikäinen-Saarenmaa] The influence of defoliation type (artificial versus natural), timing (early versus late), and intensity (25%, 50%, and 75% of needle mass removed) on leader growth of Scots pine, Pinus sylvestris (Linnaeus), was assessed for 2 years after treatment on an even-aged stand located in southeastern Finland. Trees were defoliated simultaneously, either artificially with a pair of scissors or naturally with larvae of Neodiprion sertifer (Geoffroy) and Diprion pini (Linnaeus) for the early- and late-season treatments, respectively. After 1 year, early-season artificial defoliation generally caused greater growth reduction than natural defoliation. Late-season defoliation yielded opposite results. Trees defoliated artificially in early-season treatments were significantly shorter than control trees irrespective of defoliation intensity, whereas those defoliated late in the season did not differ from controls, except at the highest intensity. Trees defoliated by sawflies, either early or late in the season, were significantly shorter than control trees only at the highest defoliation intensity. The pattern of growth loss in the second year appeared similar to that in the first year. The impact of defoliation was either prolonged neutral or negative, as no compensatory responses on height growth in Scots pine were observed. Timing of the treatment in relation to completion of leader growth, differences in defoliation types, alteration of the photosynthetic capacity due to biomass loss, and the functional role of plant parts defoliated may explain the results observed. Copyright © Entomological Society of Canada 1999 The Canadian Entomologist Cambridge University Press 131/4(1999-08), 455-463 0008-347X 131:4<455 1999 131 TCE https://doi.org/10.4039/Ent131455-4 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.4039/Ent131455-4 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Lyytikäinen-Saarenmaa Päivi Finnish Forest Research Institute, Vantaa Research Centre, PO Box 18, FIN-01301 Vantaa, Finland NATIONALLICENCE 773 0- The Canadian Entomologist Cambridge University Press 131/4(1999-08), 455-463 0008-347X 131:4<455 1999 131 TCE CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge