An easy, convenient statistical method to analyze bark beetle populations

Abstract

A non-invasive method to estimate the number of Trypodendron lineatum holes on dead standing pines (Pinus sylvestris L.) was developed using linear and nonlinear estimations. A classical linear regression model was first used to analyze the relationship between the number of holes caused by T. lineatum on selected stem units and the total number of holes on an entire dead stem of P. sylvestris. Then, to obtain a better fit of the regression function to the data for the stem unit selected in the first step, piecewise linear regression (PLR) was used. Last, in an area used to evaluate wood decomposition (method validation), the total and mean numbers of T. lineatum holes were estimated for single dead trees and for a sample (n = 8 dead trees). Data were collected in 2009 (data set D1), in 2010–2014 (data set D2) and in 2020 (data set D3) in forests containing P. sylvestris located within Suchedniów–Oblęgorek Landscape Park, Poland. A model was constructed with three linear equations. An evaluation of model accuracy showed that it was highly effective regardless of the density of T. lineatum holes and sample size. The method enables the evaluation of the biological role of this species in the decomposition of dead standing wood of P. sylvestris in strictly protected areas.