Distribution pattern of declined Brant`s oak (Quercus brantii Lindl.) trees in forests of Tol-e Ghah, Yasuj

Abstract

A forest stand of 25 ha in Tol-e Gah region nearby Yasuj (Kohgiluyeh and Boyer Ahmad province) was selected to assess the spatial distribution pattern of its dead trees of Brant`s oak (Quercus brantii Lindl). The fixed area plot samples and adaptive cluster sampling method were employed to collect qualitative and quantitative information of the forest stand. Using sixty-five, 10-Ar sample plots, quantitative characteristics of all dead trunks together with those for the healthy trees in the sample plots were recorded in a way that each dead trunk found in each of the plots was considered as the center of another sample plot. In addition to determining the geographical coordinates of the dead trunks, diameter at breast height, tree height, and crown diameter of trees were measured. The Johnson-Zimmer, Eberhart, and Pielou indices (based on the distance of the sampling spot to the individual trees) and the variance to mean ratio, Morisita index, and standardized Morisita indices (efficient in using plot samples) were applied to quantify the distribution pattern of dead trees. All sample plot-related indices indicated a clumping distribution pattern for the dead trees. Among the distance indices, the Johnson-Zimmer and Eberhart indices also showed a clumping and a uniform pattern of dead tree distribution, respectively.

Keywords

• Distribution pattern
• oak decline
• distance indices
• sample plot indices