Showing 2 results for Zagros Forest
Maryam Sisakht Nejad , Roghayeh Zolfaghari ,
Volume 1, Issue 2 (3-2015)
Abstract
Drought is the major environmental stresses that it can have a negative impact on plant growth. The study of gas exchange under drought stress can help to identify factors affecting stress resistant. Due to this fact that Zagros forests has Mediterranean and dry climate, with the aim of this study was to assess the impact of drought on leaf gas exchange in two oak species (Quercus brantii and Quercus libani). Water stress consisted of four levels of water stress (100%, 70%, 50% and 30% FC) in the greenhouse situations. Those seedlings were intended for water stress weren’t irrigated to reach to the desired field capacity (70%, 50% and 30% of field capacity), but control seedlings were irrigated every day in order to soil water content at field capacity shall be kept 100%. Results showed that water stress treatment has a significant reduction of stomatal conductance, photosynthesis, conduct mesophilic, carbon dioxide emission, and transpiration. Also Quercus libani showed higher level of photosynthesis, water use efficiency and transpiration than Quercus branti. Overall, results in both species, showed stomatal and non-stomatal limitation would cause of photosynthesis reduction. Also, due to higher water efficiency and lower gas parameter variations, Quercus libani would gain better mechanism of waster stress and Quercus brantii would gain the use drought avoidance mechanism.
Babak Pilehvar, Zahra Mirazadi, Vahid Alijani, Hamzeh Jafari Sarabi,
Volume 1, Issue 2 (3-2015)
Abstract
Considering the importance of forest structure and interaction among different tree species, this study conducted aimed to determine and compare spatial pattern, heterogeneity, and dimensions of Hawthorn and Maple trees with other neighbor trees. For determining Hawthorn and Maple trees structure, 30 individual of each trees were identified and studied. Based on the results, uniform angle index for Hawthorn and Maple trees were 0/744, and 0/733 respectively, which would propose a clumped pattern for these two species. Computed mingling index values for Hawthorn and Maple were 0/877 and 0/955 respectively that show a high tree species mixture. Also, the average of crown canopy differentiation and crown canopy dimension were 0/582 and 0/322 respectively, for Hawthorn tee and it was 0/42 and 0/656 respectively for Maple tree. Based on mean values, these results show that Hawthorn had high level of differentiation but was inferior in comparing to its neighbors whereas Maple has intermediate differentiation and is dominant to the other neighbors. The average distance to nearest neighbors for Hawthorn and Maple were calculated 7/374 and 6/278 respectively. The results of an absolute discrepancy algorithm (AD) showed a high differentiation of Hawthorn and Maple mixture in comparing to the other indices. It is concluded that maple is superior to hawthorn in dimension and because of low frequency of these two species, they hold high values of mingling indices.
