نتایج جستجو برای: origin of trees
تعداد نتایج: 21174871 فیلتر نتایج به سال:
Bracket fungi are the most important macroscopic fungi in the forest as trees are parasitic and saprophytic . This aim of this study is investigation on relate of between some of the characteristics of host and frequency of bracket fungi in district one of Shastkolate forest of Gorgan . Inventory of trees infected by bracket fungi was done using two strip transects and Factors , including the...
Cacao trees have been cultivated in Mesoamerica for at least 4,000 years. In this study, we analyzed sequence variation in the chloroplast DNA trnH-psbA intergenic spacer from 28 cacao trees from different farms in the Soconusco region in southern Mexico. Genetic relationships were established by two analysis approaches based on geographic origin (five populations) and genetic origin (based on ...
red beds, conglomerates and salt were considered azoic and problematic rocks, but paleopalynology and inorganic geochemistry proved to be useful for placing them in time and space. in the early last century, in mexican ne region, only three mesozoic red bed units were differentiated, dated as late triassic to late jurassic. it was important tratigraphically to place them properly as they were c...
Rotten and dead trees are the main component of forest ecosystems and play an important role in maintaining forest biodiversity. In this research frequency and characteristics of large diameter trees (normal, rotten, and dead trees) with diameter at breast height greater than 60 cm were studied in two compartments (selective logged and protected) in Asalem-Nav forest. Random systematic sampling...
The formation of gall is one of the various types of vegetarianism, and gall producing insects cause stress in their hosts. The present study aimed to investigate the changes of some biochemical and photosynthetic indices due to the gall in Persian oak trees in Forests of Middle Zagros. Sampling was performed from trees infected by gall and healthy trees in Blouran forests. The results showed t...
This study was conducted in oak forests of Ilam province in order to evaluate the morphological characteristics of old trees including diameter at breast height, trunk height, whole tree height, minimum and maximum crown diameter, crown health, crown vitality, crown symmetry, health and form of the trunk, Was investigated. Selection of old trees was performed based on the criteria of DBH and wi...
one of the most visible aspects of a forest stand structure is the spatial patterns of trees. competition affects on forest structure and its understanding is important, when the purpose of forest management is to imitate the dynamic of natural ecosystems. for this purpose, an unmanaged intact forest was selected with 26 hectares area. all chestnut leaf oak (quercus castaneifolia) trees with a ...
Trees can improve air quality, but at the same time, pollution might put them at risk. Plane(Platanus orientalis L) and willow trees (Salix babylonicaL) are important trees in the green space of Tehran. Plane trees in Tehran have experienced early autumn in recent years due to severe air pollution. The present study, investigated some physiological traits of these trees under study to determine...
We study the statistics of edges and vertices in the vicinity of a reference vertex (origin) within random planar quadrangulations and Eulerian triangulations. Exact generating functions are obtained for theses graphs with fixed numbers of edges and vertices at given geodesic distances from the origin. Our analysis relies on bijections with labeled trees, in which the labels encode the informat...
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