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Articles by Tuula Kantola

Category: Research article

article id 1615, category Research article
Minna Blomqvist, Päivi Lyytikäinen-Saarenmaa, Tuula Kantola, Maiju Kosunen, Mervi Talvitie, Markus Holopainen. (2016). Impacts of natural enemies and stand characteristics on cocoon mortality of the pine sawfly Diprion pini in a Fennoscandian boreal forest. Silva Fennica vol. 50 no. 5 article id 1615. https://doi.org/10.14214/sf.1615
Highlights: Annual cocoon mortality caused by natural enemies varied between 66% and 80% during the six-year study period, most of it caused by the family Ichneumonidae; Basal area, and coverage of lichen (Lichenes) and lingonberry (Vaccinium vitis-idaea L.) best explained cocoon parasitism and predation; Combination of suitable stand characteristics, abiotic environmental factors, and incomplete control by natural enemies enabled pest species to extend its gradation phase.

We investigated the impact of natural enemies on the cocoon mortality of the common pine sawfly (Diprion pini L.) during a six-year period in eastern Finland. The enemies were classified into parasitoids (insect families Chalcidoidea, Ichneumonidae, and Tachinidae), and predators (birds, small mammals, and insect families Elateridae and Carabidae). The appearance of D. pini was estimated as the intensity of annual defoliation. The impact of stand characteristics on the performance of parasitoids and predators was also investigated. Influence of the natural enemy complex on cocoon mortality of D. pini was nearly stable, but defoliation intensity slowly declined towards the end of the study period. Annual cocoon mortality by natural enemies varied between 66% and 80%. Our results verified that the most significant mortality factors were ichneumonid parasitoids and small mammals. Random Forest classification indicated that stand characteristics, such as basal area, and coverage of lichen (Lichenes) and lingonberry (Vaccinium vitis-idaea L.) affected the performance of parasites and predators. We suggest that a combination of optimal stand characteristics, abiotic environmental factors and mild to moderate control by natural enemies acted as drivers, which drove the pine sawfly population to extended gradation. For future forest health management, detailed information on abiotic and biotic regulating factors, along with long-term monitoring campaigns for conifer sawflies are needed to adapt Fennoscandian forests to altered climatic and silvicultural conditions.

  • Blomqvist, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland ORCID ID: http://orcid.org/0000-0003-2328-8839 E-mail: minna.blomqvist@helsinki.fi (email)
  • Lyytikäinen-Saarenmaa, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland ORCID ID:E-mail: paivi.lyytikainen-saarenmaa@helsinki.fi
  • Kantola, Knowledge Engineering Laboratory, Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA ORCID ID:E-mail: tuula.kantola@helsinki.fi
  • Kosunen, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland ORCID ID:E-mail: maiju.kosunen@helsinki.fi
  • Talvitie, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland ORCID ID:E-mail: mervi.talvitie@dnainternet.net
  • Holopainen, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland ORCID ID:E-mail: markus.holopainen@helsinki.fi
article id 1495, category Research article
Per-Ola Olsson, Tuula Kantola, Päivi Lyytikäinen-Saarenmaa, Anna Maria Jönsson, Lars Eklundh. (2016). Development of a method for monitoring of insect induced forest defoliation – limitation of MODIS data in Fennoscandian forest landscapes. Silva Fennica vol. 50 no. 2 article id 1495. https://doi.org/10.14214/sf.1495
Highlights: We developed and tested a method to monitor insect induced defoliation in forests based on coarse-resolution satellite data (MODIS); MODIS data may fail to detect defoliation in fragmented landscapes, especially if defoliation history is long. More homogenous forests results in higher detection accuracies; The method may be applied to future coarse and medium-resolution satellite data with high temporal resolution.

We investigated if coarse-resolution satellite data from the MODIS sensor can be used for regional monitoring of insect disturbances in Fennoscandia. A damage detection method based on z-scores of seasonal maximums of the 2-band Enhanced Vegetation Index (EVI2) was developed. Time-series smoothing was applied and Receiver Operating Characteristics graphs were used for optimisation. The method was developed in fragmented and heavily managed forests in eastern Finland dominated by Scots pine (Pinus sylvestris L.) (pinaceae) and with defoliation of European pine sawfly (Neodiprion sertifer Geoffr.) (Hymenoptera: Diprionidae) and common pine sawfly (Diprion pini L.) (Hymenoptera: Diprionidae). The method was also applied to subalpine mountain birch (Betula pubescens ssp. Czerepanovii N.I. Orlova) forests in northern Sweden, infested by autumnal moth (Epirrita autumnata Borkhausen) and winter moth (Operophtera brumata L.). In Finland, detection accuracies were fairly low with 50% of the damaged stands detected, and a misclassification of healthy stands of 22%. In areas with long outbreak histories the method resulted in extensive misclassification. In northern Sweden accuracies were higher, with 75% of the damage detected and a misclassification of healthy samples of 19%. Our results indicate that MODIS data may fail to detect damage in fragmented forests, particularly when the damage history is long. Therefore, regional studies based on these data may underestimate defoliation. However, the method yielded accurate results in homogeneous forest ecosystems and when long-enough periods without damage could be identified. Furthermore, the method is likely to be useful for insect disturbance detection using future medium-resolution data, e.g. from Sentinel‑2.

  • Olsson, Lund University, Department of Physical Geography and Ecosystem Science, Sölvegatan 12, S-223 62 Lund, Sweden ORCID ID:E-mail: per-ola.olsson@nateko.lu.se (email)
  • Kantola, Texas A & M University, Knowledge Engineering Laboratory, Department of Entomology, College Station, TX, USA ORCID ID:E-mail: tuula.kantola@helsinki.fi
  • Lyytikäinen-Saarenmaa, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: paivi.lyytikainen-saarenmaa@helsinki.fi
  • Jönsson, Lund University, Department of Physical Geography and Ecosystem Science, Sölvegatan 12, S-223 62 Lund, Sweden ORCID ID:E-mail: anna_maria.jonsson@nateko.lu.se
  • Eklundh, Lund University, Department of Physical Geography and Ecosystem Science, Sölvegatan 12, S-223 62 Lund, Sweden ORCID ID:E-mail: lars.eklundh@nateko.lu.se

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