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  • Author: Radim Matula x
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Analysis of Ecology of a Little Known White Oak Quercus Polycarpa Schur, Using Geobiocoenological Typology

Quercus polycarpa Schur is a little known oak species of the Sessile Oak aggregate (Quercus petraea s. lat.). Different habitats were studied using geobiocoenological typology system in order to investigate its ecology. In total, 65 experimental plots were set in forest stands with Q. polycarpa in the main storey in 12 protected areas situated in south-east of the Czech Republic. Ecological conditions, basic tree parameters and representation of Q. polycarpa within other oak species were evaluated on each plot. The mean values of height, height of life crown setting, stem and crown diameter were related to sub-categories of geobiocoenological system and compared by one-way ANOVA and Scheffé post-hoc test. It has been found out that Q. polycarpa grow in a high number in the 2nd altitudinal zone. It often occurs in a variety of habitats with different hydric and trophic conditions. As expected, the lowest values of measured parameters were found in the dry hydric range, this species reaches the highest values in the normal hydric and mesic ranges.

Abstract

Between 2010 and 2011 a field survey dedicated to Dracaena cinnabari (DC) population was conducted in Firmihin, Socotra Island (Yemen). It’s main goal was to collect data that would make it possible to unbiasedly estimate main characteristics of the local DC population. Our motivation was to provide reliable information to support decision-making processes as well as other research activities. At the same time we were not aware of a survey which could provide this kind of statistical-sound estimates for the whole population covering an area of almost 700 ha.

This article describes how the survey has been planned and carried out in practice. In addition, we also provide a set of preliminary estimates of the main DC population figures - totals and per hectare densities of stems, overall and partitioned according to predicted crown age. Among estimated parameters there are also mean crown age and proportions of predefined age classes on the total number of living DC stems. These estimates provide an explicit information on age structure of the whole DC population in Firmihin.

Although we collected data on more than one hundred randomly located plots, the reported accuracy of our estimates is still rather limiting. We discuss several possibilities to obtain more accurate results or at least to approach the supposedly lower true variance that can’t be calculated by approximate techniques applied here.

The design and concept of our survey makes it possible to evaluate changes over time on stem by stem bases and to generalize these stem-level details to the whole population. Mortality, regeneration and even change of population’s mean crown age can be estimated from a future repeated survey, which would be extremely useful to draw firm conclusions about the dynamic of the whole DC population in Firmihin.