In recent years, in addition to pollution from cars, factories and other polluting devices, the country of Iran has been destination dust that have entered Iraq Saudi Arabia caused climate. this research, wettability some native plants Zagros Mountains investigated experimentally by measuring contact angle. Sampling oak trees Quercus brantii Lindl. species was carried out around Khorramabad cit...

Recent research has suggested that increasing neighbourhood tree species diversity may mitigate the impact of pests or pathogens by supporting the activities of their natural enemies and/or reducing the density of available hosts. In this study, we attempted to assess these mechanisms in a multitrophic study system of young oak (Quercus), oak powdery mildew (PM, caused by Erysiphe spp.) and a m...

Variation in virulence was examined among isolates of Phytophthora ramorum from epidemiologically important or infectious (non-oak) and transmissive dead-end (oak) hosts from North America. Twelve isolates representative of the genetic, geographic and host range of P. ramorum in the western United States were inoculated on leaves of Umbellularia californica (bay laurel or bay) and stems of Quer...

Abstra.ct.-Eight hardwood species were planted at five spacings in a minor stream bottom in southeast Arkansas. Hecause of inherent differences in nutrient requirements and tree development, only four oak species are covered in this paper. Spacing gp.nerally did not affect nutrient concentrations , but differences did exist among species. Leaves constituted only 10-15 percent of aboveground bio...

Less than 10% of the acid p-nitrophenylphosphatase activity of plant extracts was sedimentable under a variety of conditions including zonal centrifugation. The sedimentable fraction did not show the latency properties characteristic of animal lysosomes. We conclude that, at least operationally, plant acid phosphatase is a soluble enzyme and that it is not suitable as a lysosomal marker. The pl...

Multivariate methods have been widely used for revealing the structures of communities, and in this paper we explore one particular method, namely correspondence analysis (also called reciprocal averaging) for studying humus profiles by the 'method of small volumes'. The present study was done on humus profiles under holm oak (Quercus rotundifolia), an evergreen Mediterranean species, in the Hi...

A deciduous tree has broad, flat leaves which it sheds in the autumn. Its seeds are enclosed in ordinary cases as for example, the oak, birch and walnut. Timber from deciduous trees is said to be 'hardwood'. It can be seen, therefore, that the term 'softwood' and 'hardwood' apply to the family or type of tree and do not necessarily indicate the density of the wood. That is why balsa, the lighte...

The stable carbon isotope composition of isoprene emitted from leaves of red oak (Quercus rubra L.) was measured. Isoprene was depleted in (13)C relative to carbon recently fixed by photosynthesis. The difference in isotope composition between recently fixed carbon and emitted isoprene was independent of the isotopic composition of the source CO(2). beta-Carotene, an isoprenoid plant constituen...

Efforts inEurope to convertNorway spruce (Piceaabies) plantations tobroadleaf ormixedbroadleaf-conifer forests could be bolstered by an increased understanding of how artificial regeneration acclimates and functions under a range of Norway spruce stand conditions. We studied foliage characteristics and leaflevel photosynthesis on 7-year-old European beech (Fagus sylvatica) and pedunculate oak (...