In order to study the effects of post-anthesis heat stress and nitrogen levels on grain yield and yield components of wheat genotypes, two separate field experiments were conducted in delayed and optimum sowing dates under Ahvaz conditions (2006-2007). The Ahvaz site located in south west of Iran (32°20' N, 40°20' E) with subtropical climate condition. The experiment site had a moderate w...

Abstract: QQ-plots are extremely useful in univariate data analysis. In this article, Koltchinskii (1997) and Chaudhuri’s (1996) definition of multivariate quantile is used to develop analogous plots for bivariate data. Bivariate qq-plots are exhibited for comparing a sample to a given population distribution (the bivariate normal), and for comparing two or more bivariate samples. The plots are...

There is a need for methodology to warm open-field plots in order to study the likely effects of global warming on ecosystems in the future. Herein, we describe the development of arrays of more powerful and efficient infrared heaters with ceramic heating elements. By tilting the heaters at 451 from horizontal and combining six of them in a hexagonal array, good uniformity of warming was achiev...

We sought to assess impacts of fire and grazing by reindeer and caribou on lichen communities in northwestern Alaska. Macrolichen abundance was estimated from 45, 0.38-ha plots. Eighteen of those plots, scattered throughout the southern Seward Peninsula, represented two levels of grazing, heavy and light. We found lightly grazed areas had taller lichens and greater total lichen cover than heavi...

Plant cover and vegetation structure were examined at two inland coastal sage scrub sites differing in fire history and use by California gnatcatchers. Salvia mellifera and Eriogonum fasciculatum dominated one site; shrub cover on gnatcatcher– occupied plots averaged 50 percent greater than on unoccupied plots. At the other site, gnatcatcher-occupied plots had high cover of Artemisia californic...