جستجوی مقالات مرتبط با کلیدواژه "caucasian alder" در نشریات گروه "جنگلداری"

In the present study, physical, chemical, and biological soil properties in pure plantation stands (21 years old) of Alnus subcordata, Populus deltoides, Cupressus sempervirens, and a mixed stand of Alnus subcordata-Populus caspica at Zaghmarz area, Neka city (north of Iran), were studied. In each stand, 10 plots of 400 m2 were selected and in each plot five samples were taken from 10 cm-depth of soil. The highest values of soil water content, pH, total nitrogen (N), phosphorus (P), potassium (K) and magnesium available (Mg), basal microbial respiration (BMR), soil microbial biomass nitrogen (MBN) allocated to stands of A. subcordata–P. caspica and A. subcordata, while the highest amounts of organic carbon (C), C:N ratio, microbial biomass carbon (MBC), and MBC/MBN ratio was observed in Cupressus stand. Analysis of PCA showed that Cupressus plantation has a positive correlation with the amount of C, CN, silt, clay, MBC, and MBC/MBN. But the pure and mixed stands of Alnus are positively correlated with total N, K, Ca, Mg, P available, water content, BMR, and MBN, showing the soil fertility of these stands and encouraging users to cultivate this species in the form of afforestation or agroforestry.

The tending operations are essential for the quantitative and qualitative improvement of forests and thinning as the most important step has a significant role in increasing the growth of trees. In this research, the even-aged alder(Alnus subcordata) and Persianmaple (Acer velutinum) stands located in Chendella district in the north of Zirab city in Mazandaran province were investigated to compare the effect of thinning on diameter growth. Three executive rotations were done in these plantations. Close to each plantation, one stand which has received no thinning treatment was selected as the control to compare the effect of thinning treatments on tree characteristics. The D.B.H and other growth parameters of 318 trees were measured. In this investigation 2 or 3 individual trees in each 5cm diameter class (totally 45 trees) were randomly selected to obtain the disk at 20 cm, 130 cm and full length heights for measuring the diameter growth rates. Medium diameter and total height of the tree were measured to calculate the diameter growth of the trees. The Student t-test with SPSS software was used to compare the quantitative characteristics of each of the forest plantations and the control. The results of this study showed that the average DBH and average diameter growth of both species in the thinned stands were higher than the control stand. Also, the mean DBH and average diameter growth in the treated and control stands of alder were more than the treated and control stands of Persian maple. However, the slenderness index of Persian maple trees in both treated and control stands was greater than that of the treated and control alder stands.The results of this study showed that the positive effects of thinning operations on the silvicultural characteristics of alder stands were much more than maple.

Field-based volume renewal methods were investigated for two tree species of oriental beech (Fagus orientalis Lipsky) and Caucasian alder (Alnus subcordata C. A. Mey.) by means of 3P and fully revised volume across district No. 10 of Sardabrood forest management plan. Field inventory included: 1) A full calipering based on 558 sampled trees (516 oriental beech and 42 Caucasian alder) and 2) 3P-based volume renewal using 96 sampled trees (81 oriental beech and 15 Caucasian alder). Compared to the total 613.89 m3 marked oriental beech wood, the renewal resulted in 489.65 m3 full calipering and 488.83 m3 3p method. In case of Caucasian alder, the total marked wood volume of 79.68 m3 was renewed to 88.62 m3 in full calipering and 82.87 m3 by 3P-method. The results indicated a reduction in volume by 10.82 m3 (Oriental beech) and 5.75 m3 (Caucasian alder) compared to full calipering method. The results obtained by t-test also revealed no significant difference between renewed volume by either of the methods for both species. Therefore, the 3P-derived values are concluded to be of high accuracy for volume renewal for practical implementations.

In order to study the effect of thinning operation on growth and wood production, an alder plantation (Alnus subcordata) on deep and moist soil with medium fertility was selected and thinned during 10 years. All standing and fallen trees were measured in terms of diameter at breast height (d.b.h), total height and standing volume. By thinning, the number of standing trees were decreased from 1700 to 400 stem per hectare. Results show that after thinning, the percentage of mortality decreased from 35% to less than 1% during 10 years. D.B.H growth, total height and standing volume increased 76%, 40% and 17%, respectively. The mean annual increment of standing volume was greater than 20 m3 for alder plantation grown on heavy and moist soil. Thus, Caucasian alder is proposed for intensive wood culture program in such areas (which are not suitable for poplars) in Caspian coastal plains.