جستجوی مقالات مرتبط با کلیدواژه « root area ratio » در نشریات گروه « جنگلداری »

The extent to which plants can protect soil largely depends on the biotechnical characteristics of their root system. One of these characteristics is the root distribution pattern in the soil or the Root Area Ratio (RAR). The aim of this study was to investigate the effect of altitude on the root spatial distribution of Caucasian alder (Alnus subcordata C. A. Mey.)trees in lower, middle and upper altitudes in the Neka-Zalmrud forestry plan in the Mazandaran province, Iran. At each site, seven trees were completely randomly sampled. In order to investigate and measure RAR, two soil profiles were dug at both up and down sides of tree samples (with 50×100 cm2 dimensions) using the profile trench method at the horizontal distance of 0.5 and 1.5 m from the tree stem. On wall trenches, 10 cm horizons were identified, on which all intersecting roots were measured and RAR was calculated in each horizon. At all three altitudes, RAR decreased exponentially with increasing depth and distance from the tree. The results of ANCOVA showed that the distribution of roots at all three altitudes was significantly different. In overall, the density of the roots increased along with increasing altitude above sea level. Higher percentages of RAR in some locations at lowland heights were probably due to limited soil depth at this height.

The roots of the plants are used as a kind of materials in the slopes preservation and resistance. Because in addition to helping to preserving and resisting the environment, it has recovery ability and has no harmful and negative effects on the environment and has no additional costs too. Plant cover is caused for pastiness between soil particles for having root system and has significant impact in slope stabilization, for this reason, the biological characteristics of different species has great importance. The quantity of reinforcement depends on root biotechnical characteristics such as root density and tensile strength. In this study assessed these biotechnical properties.

In this study, two non-native afforested stands of pine (Pinus Sylvesteres) and acacia (Robinia Peseudo acasia) and two natural stands with native species of hornbeam (Carpinus Betulus) and summer alder (Alnus Subcordata) with similar habitat conditions (altitude,Slope and direction of slope, soil type, geology, etc) in the forest of Neka city (Neka-Zalmarud forestry plan) was and Six trees of each species were randomly selected for later analysis. The Root Area Ratio and tensile strength were investigated. Profile trenching method was used to analyze and compare their root distribution. The walls of the profile are divided into 10 cm horizons. Number and diameter of protruded roots in each depth were measured. Finally, the percentage of Root Area Ratio in each horizon was calculated. Standard Santam was used to determine the tensile strength of roots. Root samples were collected at the bottom (30% slope) of trees.

The results indicated that the Root Area Ratio were decreased with increasing depth According to the exponential function . The Root area ratio in non-native species is higher than native species. Which has obtained for Carpinus Betulus, Alnus Subcordata, Robinia Peseudo acasia and Pinus Sylvesteres, 0.033±0.002, 0.081±0.002, 0.026±0.018±0.177±0.015 percent respectively. The diameter range of the tested roots was 2-9 mm. The results of tensile strength tests showed that with increasing diameter, the amount of tensile strength according to the According to the exponential function decreased. There is a positive power relationship between root diameter and tensile force.

In this research tensile strength of native species is more than non-native one that has obtained for Carpinus Betulus, Alnus Subcordata, Robinia Peseudo acasia and Pinus Sylvesteres, 31.93±10.3, 17.57±6.98, 18.4±2.41, 9.77±5.46 Mpa respectively. The results of this work may help us when applying an efficient bioengineering technique

e aim of this study was to assess spatial distribution of roots by Carpinus betulus trees in Patom district of Kheyrud forest. For this purpose, five trees at small, medium and large diameter classes were selected randomly (totally 15 trees). In order to measure root area ratio (RAR), three soil profiles were dug at both up and down sides of trees (size 50×100 cm) by wall trench method at the horizontal distance of 1, 2, and 3.5 m from tree stem (totally 90 profiles). 10 cm horizons were identified on wall trenches and all of the root diameters were measured. Finally, RAR was calculated for each soil horizon. The RAR was decreased logarithmically by increasing the soil depth. The results of ANCOVA showed significant difference between roots distribution at small, medium and large classes. The results of t-test showed that the value of the index at first, second and third trenches wall of small class at upside significantly more than down side. At medium diameter class only third trench of upside significantly more than down side. At large diameter class, first trench of upside was significantly greater than first trench of down side. The results of this study increase our information about vegetation role in stabilizing slopes and will improve the modeling of slope stability accordance to the DBH classes.

Vegetation due to its root system by creating cohesion of soil particles, significantly affects hill slope mechanical properties related to shallow landslides and slope stability. In this regard, the root engineering characteristics of forest species are important. The aim of this study was to investigate the distribution pattern of persian oak and hawthorn in Zagross forests. For this purpose, five trees from both species were randomly selected to study their root distribution. Sampling was performed by using a soil core sampling ring from three horizontal distances and three depths. Root distribution was assessed using the concept of the root area ratio. The results showed that the root area ratio as well as the longitudinal densities of the roots decreases with increasing depth of the soil and increasing the distance from the tree. The maximum root length density was observed in the initial layers and close to the trees. The highest volume density of roots was observed at depths of 0-15 cm. Based on the results of the study, it was found that there was a significant difference between the volume density of root of two persian oak and hawthorn species. Longitudinal and volumetric densities of root in persian oak were higher than hawthorn. In general, the results of this study showed the importance of persian oak in comparison with hawthorn in the field of increasing strength of soil.

Among positive effects of vegetation in erosion control, reinforcement of soil by roots is very important. The quantity of reinforcement depends on root biotechnical characteristics such as root density and tensile strength. The aim of current study is to assess the effect of traditional pollarding on root biotechnical characteristics, soil reinforcement and slope stability. To estimate the Root Area Ratio (RAR/Root density index) core sampling with cylinder cores was used. For this purpose, core samples were taken from four sides around each tree in three different soil depths. In each core, number of roots and total root length was determined for each diameter class. Root samples were collected from both up and down slope and their strength was measured with a standard Instron. The results showed that root distribution in relation to depth had a wide variation. The results of ANOVA revealed that pollarding had a significant negative effect on RAR. Also the results of Wald chi square showed that pollarding had a significant negative effect on tensile strength of roots. Mean RAR values of fine roots in control and pollarding samples were 47.0 and 28.0%. Mean tensile resistance in control and pollarding samples were 40.31 and 19.94 MPa, respectively. The average reinforcement of fine roots in control and pollarding samples were 2.29 kPa and 1.12 kPa. The results of this study confirmed that traditional pollarding not only have negative effect on aboveground biomass of oak trees but also significantly reduce the positive effect of vegetation on soil reinforcement.

Vegetation enhances the soil resistance against instability and erosion through increasing the soil cohesion. The main effect of vegetation in stability improvement is soil reinforcement by roots. The amount of reinforcement depends on distribution and strength of roots. The aim of this study was to assess the quantity of these two parameters of Persian oak roots and also comparing the tensile strength and reinforcement effect of roots in winter and summer seasons. Damage survey method was used to assess the distribution of roots. The diameters of all roots in trenches were measured by a digital caliper. Some root specimens were randomly selected from five tree samples and their tensile strengths were measured using a standard Instron. The range of root diameter and corresponding force and tensile strength were 0.1-5.5 mm, 1.3-411.3 N and 0.93-1217.39 MPa, respectively. Maximum and minimum root densities were in 0-10 and 50 cm soil horizons. The maximum reinforcement effect was belong to winter and 0-10 cm horizon. Minimum and maximum reinforcement effects for winter season were 0.0001 and 3.37 and 0.0004 and 2.87 MPa for summer.

The root of vegetation is known to increase the hill-slope stability by reinforcing soil shear strength. The amount of reinforcement depends on density and tensile strength of roots therefore this study assessed these biotechnical properties. The profile trenching methods was used to obtain root area ratio (RAR) and number and diameter of roots in each depth were measured. Standard Insrton was used to determine the tensile strength of roots. The results indicated that the root density and number of root were decreased with increasing depth. Tensile strength is decreased with diameter of roots following power function with an average of 16. 29 MPa. Using the results of biotechnical characteristics and Wu model، the reinforcement effect was calculated and minimum and maximum of reinforcement were 0. 55 KPa and 110. 76 KPa، respectively. The results presented in this paper can be used for hill-slope stability with bioengineering method.