[The model of refoliation level in oak crowns after damage by phyllophages]
2007
Rubtsov, V.V. | Utkina, I.A.
The refoliation level (the level of regenerative tillering and leaf formation) in oak crowns (RL) after damage by leaf-eating insects: green oak leaf roller (Tortrix viridana), unpaired silkworm (Lymantria dispar), winter geometrid (Oerophtera brumata), oak thatch slender (Acrocercops brongniardella) is studied. The researches are carried out in different types of oak groves in southern forest-steppe (Voronezh region ). Dry weight or leaf-area duration of regenerative shoots per a unit 0.01 m length of current year shoots characterize best of all RL ; parameters related to total foliage mass do it worse. A mathematical model, which allows to calculate probabilistic estimates of RL in oak crowns after their damage by phyllophages, was developed.At modelling RL is calculated as a ratio of total foliage dry weight of trees after refoliation to total foliage dry weight of trees without defoliation. Both indices are computed per a unit 0.01 m length of current year shoots. The maximal defoliation degree and characteristic of weather conditions during secondary foliage regrowth serve as input information. Hydrothermic coefficients for June, May-June and June-July are taken for this purpose. RL is an output variable of the model. Parameters of the model are identified for various types of oak groves. The model can be used for probability forecasts of RL in other regions and objects after having made corresponding parametrical identification.
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