Abstracts

Forest Ecosystems

A so-called “fixed outbreak” of Monochamus urussovi Fisch. in fir stands is a peculiar state of the stand-insect system. This type of the pest outbreak occurs under certain conditions determined by the stand structure and status. The outbreak doesn’t turn into the fixed one even in a stand weakened by leaf-eating insects if the stand phytocenotic structure doesn’t corresponds to the outbreak requirements.

The tree gets suitable for infesting at a certain level of the crown damage by the beetles. The beetles number is limited by the stem size. For estimating the probability of long-term existence of the pest in the stand we offered to calculate of a special parameter q. The q value is the ratio of the potential beetle number to the their fodder base. The more q the more favorable condition for the fixed outbreak.

To calculate q for the sample plot where the tree diameters were measured is not difficult. But regular forest inventory data don’t contain information on tree diameters. So they can’t be applied for calculating parameter q and wide-scale estimation of stand resistance.

There has been developed procedure for calculating q basing on forest inventory data. The approach presented is grounded on modeling stand structure, calculating mensuration paramaters of the sample stands, and solving the inverse task – reconstruction of stand structure by the forest inventory data. The method developed allows us estimate q for any fir stand by the forest inventory data and evaluate the resistance of the stand to Monochamus urussovi Fisch outbreak.

To verify the method respective calculations were carried out by the data on tree diameters and pest population distribution in stands differed by damage level in 1999-2000 were applied.

The research was financially supported by RFBR (project 99-04-49450 and 00-04-48990).

Note. Abstracts are published in author's edition

|Home Page| |English Part|

Go to Home