Water shortage is one of the most important environmental stresses in Mediterranean regions. Poor seedling quality may account for the failure of oak regeneration. To determine the best seed origin of Quercus brantii, we investigated on seedlings collected from 20 mother trees in the Zagros Mountain forests 700 to 2200 m altitudes above sea level. Seedlings from different altitudes were irrig...

Climate change is expected to change the distribution of species. For long-lived, sessile species such as trees, tracking the warming climate depends on seedling colonization of newly favorable areas. We compare the distribution of seedlings and mature trees for all but the rarest tree species in California, Oregon and Washington, United States of America, a large, environmentally diverse regio...

A widely accepted hypothesis in invasion ecology is that invasive species have higher survival through the early stages of establishment than do non-invasive species. In this study we explore the hypothesis that the sexual reproductive success of the invasive trees Ailanthus altissima (Mill.) Swingle and Robinia pseudoacacia L. is higher than that of the native Fraxinus angustifolia Vahl., all ...

The characteristic decline in height growth that occurs over a tree's lifespan is often called "age-related decline." But is the reduction in height growth in aging trees a function of age or of size? We grafted shoot tips across different ages and sizes of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees to determine whether the decline in height growth is mediated by tree size or by t...

PREMISE OF THE STUDY In dioecious species, selection should favor different leaf sizes in males and females whenever the sexes experience distinct environments or constraints such as different costs of reproduction. We took advantage of a long-term experimental study of Ocotea tenera (Lauraceae), a dioecious understory tree in Monteverde, Costa Rica, to explore leaf size differences between gen...

This study was conducted at the Gorgan University of Agricultural Sciences and Natural Resources farm, Iran, Golestan province with about 600 mm annual rainfall in order to evaluate the effect of different sowing dates on Azivash (Corchorusolitorius) seed quality, using a randomized complete block design with three replications on 2013. Treatments were four sowing dates such as May 5, ...

plane and mulberry trees play a crucial role in purifying the polluted air in tehran as a majorcity. in this research, 13 main districts of tehran city were chosen as study area. 20 completely healthy planeand mulberry species were selected in similar ecological conditions and age range. the uptake of cd and pbwas determined using spectrophotometry, whereas the chlorophyll content was measured ...