For maintaining of Zagros forests role in wild life, water and soil conservation, the suitable solutions and methods for assessing the existing conditions and planning for management of this forests should be given. To detection of suitable sampling method to study tree Diameter at Breath Height in the northern Zagros forest, Blake forest, in Baneeh region, Kurdistan province, and west of Iran ...

For maintaining of Zagros forests role in wild life, water and soil conservation, the suitable solutions and methods for assessing the existing conditions and planning for management of this forests should be given. To detection of suitable sampling method to study tree Diameter at Breath Height in the northern Zagros forest, Blake forest, in Baneeh region, Kurdistan province, and west of Iran ...

Ewens' sampling formula, the probability distribution of a configuration of alleles in a sample of genes under the infinitely-many-alleles model of mutation, is proved by a direct combinatorial argument. The distribution is extended to a model where the population size may vary back in time. The distribution of age-ordered frequencies in the population is also derived in the model, extending th...

A number of studies have demonstrated that bacteria and fungi are present in the stratosphere. Since the tropopause is generally regarded as a barrier to the upward movement of particles it is difficult to see how such microorganisms can reach heights above 17 km. Volcanoes provide an obvious means by which this could be achieved, but these occur infrequently and any microorganisms entering the...

A typical way to quantify aboveground carbon in forests is to measure tree diameters and use species-specific allometric equations to estimate biomass and carbon stocks. Using "citizen scientists" to collect data that are usually time-consuming and labor-intensive can play a valuable role in ecological research. However, data validation, such as establishing the sampling error in volunteer meas...

The properties of a variable area sampling technique, by which the observer varies the searchradius to obtain approximately a prescribed number of woody plants in each tier measured, were determined by (i) comparison of fixed area and variable area sampling of a computer-mapped shrub population; (ii) comparison of results from fixed area and variable area sampling of woody plants exceeding abou...