Responses of Scots pine to nickel and copper exposure and herbivory

• Main Author: Roitto, Marja
• Other Authors: Niemelä, Pekka, University of Helsinki, Faculty of Biosciences, Department of Ecological and Environmental Sciences, Oulun yliopisto, Helsingin yliopisto, biotieteellinen tiedekunta, ympäristöekologian laitos, Helsingfors universitet, biovetenskapliga fakulteten, institutionen för miljöekologi, Markkola, Annamari, Strömmer, Rauni, Rautio, Pasi
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Helsingin yliopisto 2010
• Subjects: ympäristöekologia; Kola Peninsula; The Needles; kola peninsula
• Online Access: http://hdl.handle.net/10138/22099

The goal of this thesis was to examine the ecophysiological responses of Scots pine (Pinus sylvestris L.), with an emphasis on the oxidative enzyme peroxidase and plant phenolics to environmental stresses like elevated levels of nickel (Ni) and copper (Cu), and herbivory. The effects of Ni and Cu were studied in a gradient survey at a sulphur dioxide contaminated site in the Kola Peninsula, and with experiments in which seedlings were exposed to Ni mist or to Ni and Cu amended into the soil. In addition, experimental Ni exposure was combined with disturbance of the natural lichen cover of the forest ground layer. Pine sawfly attack was simulated in the early season defoliation experiment, in which mature Scots pine were defoliated (100 %) during two successive years in a dry, nutrient-poor Scots pine stand. In addition, the effect of previous defoliation on the growth of sawfly (Diprion pini L.) larvae was studied. Apoplastic peroxidase activity was elevated in the needles of pine in a Ni- , Cu- and SO2- polluted environment, which indicated an increased oxidative stress. Increased foliar peroxidase activity due to Ni contamination was shown in the experiment, in which Ni was added as mist. No such response was found in peroxidase acitivity of the roots exposed to elevated Ni and/or Cu in the soil. Elevated Ni in the soil increased the concentration of foliar condensed tannins, which are able to bind heavy metals in the cells. Addition of low levels of Ni in the soil appeared to benefit pine seedlings, which was seen as promoted shoot growth and better condition of the roots. Wet Ni deposition of 2000 mg m-2 reduced growth and survival of pine seedlings, whereas deposition levels 200 mg m-2 or 20 mg m-2 caused no effects in a 2-y lasting experiment. The lichen mat on the forest floor did not act as an effective buffer against the adverse impacts of heavy metals on pine seedlings. However, some evidence was found indicating that soil microbes profited from the lichen mat. Artificial defoliation increased ...