Evaluation physiographic factors on oak sprout structure in mountain forest of west of Iran.
Regeneration of branching forests occurs through stimulation of growing buds which is called asexual reproduction. These buds are located under the skins of trees stem and root in 2 forms of adventitious buds and preventitious buds. Upon cutting or stimulating the tree, these buds begin to grow and form the sprouts. [14,5,12,9] which are classified as two general types including stump shoot and root stock depending on their origins.
Forests reproducing in asexual fashion, have an old history [3,10,5]. This forest management method has been considered initially for supplying fuel (wood and coal) and its main principle is presence of tree species with good sprouting capability. Various factors affect on sprouting and sprout--clump structure, most important of them are species, age, physiographic factors, edaphic factors, cutting height, cutting method, climatic factors and fire. [13,7,11,6,2].
In present study, given the necessity of this is issue, we have focused only to study on sprout clump stricture, oak sprout generation and their relation to physiographic factors (altitude from sea level, direction, land slope and from).
Few studies performed on this subject we will refer to most important of them.
In a study on tree species including Quercus libani olive, Quercus infectoria and Quercus brantii in Gavzian region, Marivan Concluded as follows : All species of oak tree don't have an equal sprouting potency. Sprouting in Quercus brantii was higher than Quercus libani olive. The number of sprout in various oak species has a direct relationship to forest utilization. In another two separate study stated on oak regeneration as follows: The more altitude from sea level is increased, the more oak sprout number is dcreased. In a study on Quercus brantii in forests found out that 56% of regeneration in Quercus brantii in this region is asexually. And greatest regeneration is observed in south -western hillside. In another study on natural regeneration of 3 oak species including Quercus brantii, Quercus infectoria and Quercus libani olive in forests, it was demonstrated that oak spouting rate in northern hillsides is higher and the number of oak sprouts decreases with increased altitude from sea level. Gracia & Retana  also by harvesting from 12 sample plots in two hillsides with average altitudes 300 and 500 m from sea level. Studied and it was demonstrated that sprouting potency of this species is considerably higher in lower altitudes compared to upper altitudes.
Materials and Methods
A part of forests belonged to kooseh village with 430 hectare area located in, kermanshah province was selected to perform this study (Figure 1). This region is located in 46[degrees], 25' to 46 [degrees] 30' E longitudes and 34[degrees] 35' to 34[degrees] 40' N altitude. Study area totally has a temperate climate and its precipitation in winter is mostly in the form of snow and in other seasons is in the form of rain. The region has five dry months during the year. Precipitation rate is 450 mm annually and its average annual temperature is 13.2 C [degrees]. Minimum and maximum altitude from sea level in study area is 1580 and 2045 m, respectively. This area has a steep slope so that average slope is 38% and dominant aspect is southern.
After initial land identification and primary forest walking, area range was defined on topographic map with 1:50,000 scale and according to map scale, a grid was drawn with 200 x 250m diminution for sampling. This grid was mounted in regular--random method firstly on forest map and them in the nature. Sample plots were square shaped with an area of 1600 [m.sup.2] and diminutions of 40 x 40 m were placed on grid tops .
Totally 84 sample plots were harvested in study area. In each sample plot, altitude from sea level, dominant slope, dominant aspect, land form including crest, valley and range (table 1), species, the number of sprout clump (altitude of highest sprout clump), big and small diameters of sprout clump's crown (to calculate crown surface of sprout clump) and sprout clumps section surface (using collar diameter of sprouts existing in sprout clump with 2.5 cm diameter counting limit) were recorded in demographic form. It must be remind that since measurement of sprout's collar diameter in the forest is very cumbersome, for the purpose of calculation of section surface in each sprout clump, firstly diameter layer with greatest number of sprouts was estimated and it was considered as average diameter of sprouts existing in sprout clump. (Since it was found in primary forest walking that this forest is very young and diameter range of sprouts is very small, thus this method was applied). Then section surface was calculated and multiplied in the number of sprouts existing in sprout clump.
Forest type was defined based on species composition.Additionally, topographic map of the region and maps, for aspect and height classes were prepared by using geographic information system and software Arc GIS (Figures 2). Altitude was divided to 5 classes including 1600 - 1700, 1700 - 1800, 1800 - 1900, 1900 - 2000 and > 2000 m. For the purpose of classification geographic direction, main directions were use.
Firstly consistence of initialized data from normal distribution was studied by using Kolmogrov --Smirnov test. Pearson correlation was used to study correlation between variables Additionally, one--way analysis of variance (ANOVA) was used to study difference or indifference in classes of altitude from sea level, direction and slope based on quantitative characteristic of oak sprout clump. Using equation (1), geographic direction conversion was performed to use in analysis .
Aspect = Cos ( 45 - A) + 1 (1)
Results Data analysis indicated that there are 9 tree and shrub species in studied forest including:
Quercus brantii, Quercus infectoria, Acer monspessulanum subsp. cinerascens, pistacia atlantica, pyrus syriaca, crataegus meyeri, Lonicera nummulariifolia, Amygdalus orientalis and cerasus microcarpa. Species composition in this forest is as follows: 64% Quercus brantii, 11% Quercus infectoria, 7.5% pistacia atlantica, and remainder is comprised of other species. Them forest type is achieved in the form of Quercus brantii--Quercus infectoria main type. 64% of oak species were, Average number of sprouts in each sprout clump was estimated 5.9 and section surface in each hectare of was 1.45 m2. Minimum and maximum number of oak sprout clump were 2 and 27, respectively. Since the number of Quercus infectoria was little, it wasn't possible to differentiate the results depending on oak species. Thus results were generally analyzed for both species.
[FIGURE 2 OMITTED]
Quantitative Analysis of Physiographic Factors Altitude from Sea Level:
Study of relationship between number of oak sprout and changes of altitude from sea level reflects strong, negative correlation of these two variables (P<0.01). In addition variance analysis of quantitative properties including number of sprouts in hectare, section surface, maximum altitude and crown surface of sprout clump, with different altitude classes from sea level demonstrates that there is a significant difference up to 1% between them. That is, changes in altitude from sea level affect.
On above mentioned structural properties (Table 1). Comparison of average number of sprout in hectare using Duncan method indicates that difference of this factor is not significant only between altitude classes of 1800 - 1900 m and 1900 - 2000 m. In other cases there is significant difference (Figure 3).
Relationship between physiographic factor of slop and number of oak sprout in hectare has a large, negative correlation (P < 0.001). In other word, the number of sprouts are decreased with in creased slope percentage. One--way analysis of variance of variables including the number of sprout in hectare and sprout clump crown surface in different slope classes represents a significant difference in 1 % level between them.
But there is no significant difference between other factors in different classes of slope. In other words, range slope has not significant effect on these factors (Table 3). Comparing average sprout number in hectare by using Duncan method in different slope classes indicates that class 0 - 20 has a significant difference to other classes, but there is no significant difference between two other classes (Figure 4).
Study of correlation coefficient between range direction and number of oak sprouts demonstrated that their relationship in significant in test level with P <0.01, variance analysis of two variables indicate that there is significant difference between then in 1% level. But other structural factors didn't show significant difference with change in direction classes (Table 4). Comparison of average sprout number in hectare using Dunkan method in different geographic directions indicates that difference of sprout number in hectare in south, east and west directions with northern direction is significant.
Variance analysis of studied factors related to various land forms is given in table 5. It is concluded from results of this study that there is no significant difference between Quantitative factors studied in 3 land form including crest, valley and range. That is, all three growing region forms have similar function structural factors. Comparison of average number of sprout in hectare using Dunkan technique in difference of oak represents significant difference of oak sprouting capacity in 3 mentioned forms.
As discussed in introduction, trees sprouting are related to several factors but in present study we focus only on role of physiographic factors.
Among other important factors influencing on structure of oak sprout clumps studied up to date in Zagross forests are species and age. In this respect, Oak species sprouting capability play on important role in regeneration of Zagross forests. This has resulted to generation of forest in a wide spectrum of western part of the country. In present study was demonstrated that in average there is 5.9 sprouts in each oak sprout clump in Upper Baba--Koaseh forest.
Minimum and maximum numbers of sprouts existent in each oak sprout clump are 2 and 27 respectively. In Zagross forests there are in average 10 to 30 sprout in each oak sprout clump. In forests, average number of sprout in oak sprout clump is 24.5 sprouts. Minimum and maximum sprouts in sprout clump are 2 and 24 sprout, respectively. Explained average number of sprout in each oak sprout clump as 6.4 sprouts. Thus, generally it could be concluded that sprouts density is low in Baba--kooseh forest.
On the other hand, results of this study indicated that effect of altitude from sea level on the number of oak sprouts is significant. So that number of sprout will decrease with increased altitude from sea level. Gracia & Retana  also confirmed this fact in their results that was mostly due to decreased temperature with increased altitude from sea level. Since temperature has a positive effect on sprouting decreased temperature will decrease sprouting capacity.
Its main reason may be distribution of Quercus libani olive in higher altitudes compared to Quercuse infectoria and brantii which is naturally related to climatic factor of temperature. Effects of slop and direction were also significant on the number of oak species sprouts. So that the number of oak sprouts will decrease with increased slope rate.
Studies by Wegel & Johnson  confirmed this. It is not worthy that soil physical and chemical properties including depth, acidity, texture, organic matter and nutritional elements are among very effective factors on sprouting  and they may over shadow some other factors. Thus it is recommended that in future studies, edaphic factors role on sprouting and on structure oak sprout clump also being studied in this area. It is Possible that in this study, decreased number of oak sprouts with increased range slope being due to decreased depth and fertility of soil in step slopes.
Additionally according to the results of this study, the numbers of oak sprouts in southern eastern and western directions have no significant difference from each other. But have significant different to northern direction. So that lowest number of sprout was observed in northern ranges. Generally since southern ranges in north hemisphere has higher sunshine than other directions and are warmer, than sprouting is higher in these ranges .
Of course, he explained it is due to more server and frequent cutting of oak trees in northern ranges of forest due to its accessibility for woods men.
It is worth mentioning that in these study area human factors in mild slopes and in mentioned direction was partially effective due to the fact that forests located in southern ranges are in small distance form village.
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Here to, I thank honorable staffs of research center of kermanshah province for their valuable helps.
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Seyed Armin Hashemi
Department of Forestry, Lahijan Branch, Islamic Azad University, Lahijan, Iran.
Seyed Armin Hashemi, Department of Forestry, Lahijan Branch, Islamic Azad University, Lahijan, Iran.
Table 1: Quantitative characteristics of factors studied in study area. Number of sample Area Studied factors Layers plots (hectare) % Altitude from 1600-1700 15 77.9 18 sea level 1700-1800 15 77.6 18 1800-1900 28 142.2 33 1900-2000 21 107.7 25 >2000 5 25.9 6 Slope (%) 0-12 9 48 11 30-Dec 27 137.9 32 >30 48 245.7 57 Aspect North 13 68.9 16 South 49 249.9 58 East 12 60.3 14 west 10 51.7 12 Land form 12 -- -- 10 -- -- 62 -- -- Table 2: One way analysis of variance of oak sprout clump structure with changes of altitude from sea level. Studied factor F rate Significance level Number of sprout in hectare 12.851 0.000 Maximum height of sprout clump 4.627 0.002 Section surface of sprout clump 2.994 0.025 Crown surface of sprout clump 8.798 0.000 Table 3: One way analysis of variance on oak sprout clumps structure with slope changes Studied variable F rate Significance level Number of sprout in hectare 9.947 0.013 Maximum height of sprout clump 2.464 0.091 Section surface of sprout clump 0.253 0.777 Crown surface of sprout clump 4.464 0.027 Table 4: One way variance analysis of oak sprout clumps with directional changes Oak sprout clumps with directional changes. Studied variable F rate Significance level Number of sprout in hectare 4.52 0.02 Maximum height of sprout clump 2.479 0.067 Section surface of sprout clump 1.552 0.207 Crown surface of sprout clump 1.688 0.176 Table 5: One way variance analysis of oak sprout clumps with changes in land form. Studied variable F rate Significance level Number of sprout in hectare 1.388 0.265 Maximum height of sprout clump 0.916 0.404 Section surface of sprout clump 1.045 0.356 Crown surface of sprout clump 1.75 0.181
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|Title Annotation:||Original Article|
|Author:||Hashemi, Seyed Armin|
|Publication:||Advances in Environmental Biology|
|Date:||Aug 1, 2011|
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