Biomechanical characteristics of the root system of hornbeam(Carpinus betulus) were assessed by measuring Root Area Ratio(RAR) values and tensile strength of root specimens of eight hornbeam trees growing on hilly ter...Biomechanical characteristics of the root system of hornbeam(Carpinus betulus) were assessed by measuring Root Area Ratio(RAR) values and tensile strength of root specimens of eight hornbeam trees growing on hilly terrain of Northern Iran.RAR values of the roots were obtained using profile trenching method at soil depth of the top 0.1 m.In total 123 root specimens were analyzed for tensile strength.Results indicate that in general, RAR decreases with depth, following a power function.The RAR values in up and down slopes have no significant statistical differences.In most cases, the maximum RAR values were located in soil depth of the top 0.1 m, with maximum rooting depth at about 0.75 m.The minimum and maximum RAR values along the profiles were 0.004% and 6.431% for down slope and 0.004% and 3.995% for up slope, respectively.The number of roots in the up and down slope trenches was not significantly different.In the same manner as for RAR, number of roots distributing with depth was satisfactorily approximated a power function.The penetration depths of above 90 percent of the roots were at soil depths of 50 cm and 60 cm for up and down slopes, respectively.Results of Spearman's bivariate correlation showed no significant correlation between the RAR value with tree diameter and gradient of slope and number of roots.The mean value of root tensile strength was 31.51 ± 1.05 MPa and root tensile strength decreased with the increase in root diameter, follow-ing a power law equation.Using ANCOVA, we found intraspecies variation of tensile strength.展开更多
<span style="font-family:Verdana;">The use of wood has been considered for a long time and to this day, it has a special place in human life. Modification of wood and lignocellulosic materials is done ...<span style="font-family:Verdana;">The use of wood has been considered for a long time and to this day, it has a special place in human life. Modification of wood and lignocellulosic materials is done by various methods, including modification of physical, mechanical, chemical and thermal, that as a new technology, it leads to the improvement of their undesirable features. Among these methods, heat correction is a useful method to improve dimensional stability and leads to increased resistance to water absorption and decay. The main purpose of this study is to investigate the titanium Nano oxide and heat treatment on the physical properties of hornbeam species. Samples were saturated with titanium Nano oxide solution at a concentration of 5000 ppm and pressurized 7 times in a pressure tank. The samples were divided into three groups: control, heat and Nano thermal treatment. Heat and saturated samples with titanium Nano oxide were heat treated at three temperature levels of 150</span><span style="font-family:""><span style="font-family:Verdana;">℃</span><span style="font-family:Verdana;">, 175</span><span style="font-family:Verdana;">℃</span><span style="font-family:Verdana;"> and 200</span><span style="font-family:Verdana;">℃</span><span style="font-family:Verdana;"> for 4 and 6 hours. All three groups underwent physical tests. Heat and Nano thermal oxide treatments led to reduced water absorption and thickness swelling. Comparison between heat and Nano thermal treatment showed a further decrease in water absorption and thickness swelling in Nano thermal samples.展开更多
We conducted a study to examine the pattem of develop- ment of herbaceous plant species, woody species regeneration and soil physical characteristics after tree uprooting in 20-ha areas of Experimen- tal Forest Statio...We conducted a study to examine the pattem of develop- ment of herbaceous plant species, woody species regeneration and soil physical characteristics after tree uprooting in 20-ha areas of Experimen- tal Forest Station of Tarbiat Modares University located in a temperate forest of Mazandaran province in the north of Iran. Soil bulk density, soil texture and moisture from pit and mound (PM) were measured in the laboratory. Results show that the soil bulk density was most in soil deeper layers at mound top, and the soil moisture content was most in soil deeper layers at Pit bottom. Our study supports that the mi- cro-topography of PM (pit and mound) topography will create a mosaic of environmental conditions. This environmental heterogeneity could be responsible for the diversity of herbaceous plant species and regeneration of woody species. It is recommend that the fallen trees with PM structure should remain in the protected area without clearing as the best option for forest restoration. This information can be useful for forest management that attempts to emulate natural processes.展开更多
Biomechanical characteristics of the root system of hornbeam (Carpinus betulus) were assessed by measuring Root Area Ratio (RAR) values and tensile strength of root specimens of eight hornbeam trees growing on hil...Biomechanical characteristics of the root system of hornbeam (Carpinus betulus) were assessed by measuring Root Area Ratio (RAR) values and tensile strength of root specimens of eight hornbeam trees growing on hilly terrain of Northern Iran. RAR values of the roots were obtained using profile trenching method at soil depth of the top 0.1 m. In total 123 root specimens were analyzed for tensile strength. Results indicate that in general, RAR decreases with depth, following a power function. The RAR values in up and down slopes have no significant statistical differences. In most cases, the maximum RAR values were located in soil depth of the top 0.1 m, with maximum rooting depth at about 0.75 m. The minimum and maximum RAR values along the profiles were 0.004% and 6.431% for down slope and 0.004% and 3.995% for up slope, respectively. The number of roots in the up and down slope trenches was not significantly different. In the same manner as for RAR, number of roots distributing with depth was satisfactorily approximated a power function. The penetration depths of above 90 percent of the roots were at soil depths of 50 cm and 60 cm for up and down slopes, respectively. Results of Spearman's bivariate correlation showed no significant correlation between the RAR value with tree diameter and gradient of slope and number of roots. The mean value of root tensile strength was 31.51 ± 1.05 MPa and root tensile strength decreased with the increase in root diameter, following a power law equation. Using ANCOVA, we found intraspecies variation of tensile strength.展开更多
Dead trees, particularly downed logs, play an important role in the dynamics of forest ecosystem. Contribution of decaying wood to C and nutrient pools of forest soils depends on the tree species and degree of wood de...Dead trees, particularly downed logs, play an important role in the dynamics of forest ecosystem. Contribution of decaying wood to C and nutrient pools of forest soils depends on the tree species and degree of wood decay. However, the extent to which the downed logs affect the soil properties of temperate forests has rarely been evaluated. In this study, a mixed beech forest was selected in Liresar region of Mazandaran Province, northern Iran, to investigate if and how the presence of downed logs affected soil quality and function by comparing soils underneath degraded logs and nearby soils of the two dominant tree species(beech and hornbeam). We then explored how these effects occurred as downed logs decomposed by comparing the woods of both tree species at four degrees of decomposition. Degree of decay of downed logs was classified into four classes(DC1–DC4). Eight dead trees of each tree species were selected at the center of each sample plot. Three composite soil samples underneath each decaying log and 100 cm away from a decaying log were collected at two soil depths(0–15 and 15–30 cm) to analyze soil main physicochemical properties and microbial activity. The results revealed that downed logs affected soil physical(5% wetter than control soils), chemical(2% lower pH, 100% increase in organic C and total N in the case of hornbeam, and 2% increase in P), and biological characteristics(soil microbial respiration enhanced by 10%, and microbial biomass C 620 and 351.5 mg kg-1 and microbial biomass N 66.47 and 32.18 mg kg-1, respectively, in the cases of beech and hornbeam), thus resulting in significantly different soil microsites from those without downed logs. Presence of downed logs increased soil microbial activity and soil fertility as wood decayed. Thus, the presence of downed logs is an important factor influencing forest soils and should be taken into consideration in forest management practices.展开更多
文摘Biomechanical characteristics of the root system of hornbeam(Carpinus betulus) were assessed by measuring Root Area Ratio(RAR) values and tensile strength of root specimens of eight hornbeam trees growing on hilly terrain of Northern Iran.RAR values of the roots were obtained using profile trenching method at soil depth of the top 0.1 m.In total 123 root specimens were analyzed for tensile strength.Results indicate that in general, RAR decreases with depth, following a power function.The RAR values in up and down slopes have no significant statistical differences.In most cases, the maximum RAR values were located in soil depth of the top 0.1 m, with maximum rooting depth at about 0.75 m.The minimum and maximum RAR values along the profiles were 0.004% and 6.431% for down slope and 0.004% and 3.995% for up slope, respectively.The number of roots in the up and down slope trenches was not significantly different.In the same manner as for RAR, number of roots distributing with depth was satisfactorily approximated a power function.The penetration depths of above 90 percent of the roots were at soil depths of 50 cm and 60 cm for up and down slopes, respectively.Results of Spearman's bivariate correlation showed no significant correlation between the RAR value with tree diameter and gradient of slope and number of roots.The mean value of root tensile strength was 31.51 ± 1.05 MPa and root tensile strength decreased with the increase in root diameter, follow-ing a power law equation.Using ANCOVA, we found intraspecies variation of tensile strength.
文摘<span style="font-family:Verdana;">The use of wood has been considered for a long time and to this day, it has a special place in human life. Modification of wood and lignocellulosic materials is done by various methods, including modification of physical, mechanical, chemical and thermal, that as a new technology, it leads to the improvement of their undesirable features. Among these methods, heat correction is a useful method to improve dimensional stability and leads to increased resistance to water absorption and decay. The main purpose of this study is to investigate the titanium Nano oxide and heat treatment on the physical properties of hornbeam species. Samples were saturated with titanium Nano oxide solution at a concentration of 5000 ppm and pressurized 7 times in a pressure tank. The samples were divided into three groups: control, heat and Nano thermal treatment. Heat and saturated samples with titanium Nano oxide were heat treated at three temperature levels of 150</span><span style="font-family:""><span style="font-family:Verdana;">℃</span><span style="font-family:Verdana;">, 175</span><span style="font-family:Verdana;">℃</span><span style="font-family:Verdana;"> and 200</span><span style="font-family:Verdana;">℃</span><span style="font-family:Verdana;"> for 4 and 6 hours. All three groups underwent physical tests. Heat and Nano thermal oxide treatments led to reduced water absorption and thickness swelling. Comparison between heat and Nano thermal treatment showed a further decrease in water absorption and thickness swelling in Nano thermal samples.
文摘We conducted a study to examine the pattem of develop- ment of herbaceous plant species, woody species regeneration and soil physical characteristics after tree uprooting in 20-ha areas of Experimen- tal Forest Station of Tarbiat Modares University located in a temperate forest of Mazandaran province in the north of Iran. Soil bulk density, soil texture and moisture from pit and mound (PM) were measured in the laboratory. Results show that the soil bulk density was most in soil deeper layers at mound top, and the soil moisture content was most in soil deeper layers at Pit bottom. Our study supports that the mi- cro-topography of PM (pit and mound) topography will create a mosaic of environmental conditions. This environmental heterogeneity could be responsible for the diversity of herbaceous plant species and regeneration of woody species. It is recommend that the fallen trees with PM structure should remain in the protected area without clearing as the best option for forest restoration. This information can be useful for forest management that attempts to emulate natural processes.
文摘Biomechanical characteristics of the root system of hornbeam (Carpinus betulus) were assessed by measuring Root Area Ratio (RAR) values and tensile strength of root specimens of eight hornbeam trees growing on hilly terrain of Northern Iran. RAR values of the roots were obtained using profile trenching method at soil depth of the top 0.1 m. In total 123 root specimens were analyzed for tensile strength. Results indicate that in general, RAR decreases with depth, following a power function. The RAR values in up and down slopes have no significant statistical differences. In most cases, the maximum RAR values were located in soil depth of the top 0.1 m, with maximum rooting depth at about 0.75 m. The minimum and maximum RAR values along the profiles were 0.004% and 6.431% for down slope and 0.004% and 3.995% for up slope, respectively. The number of roots in the up and down slope trenches was not significantly different. In the same manner as for RAR, number of roots distributing with depth was satisfactorily approximated a power function. The penetration depths of above 90 percent of the roots were at soil depths of 50 cm and 60 cm for up and down slopes, respectively. Results of Spearman's bivariate correlation showed no significant correlation between the RAR value with tree diameter and gradient of slope and number of roots. The mean value of root tensile strength was 31.51 ± 1.05 MPa and root tensile strength decreased with the increase in root diameter, following a power law equation. Using ANCOVA, we found intraspecies variation of tensile strength.
基金This study was funded by the financial supports from Tarbiat Modares University,Iran.I am grateful to Mr.S.Boor for the help with laboratory analyses.
文摘Dead trees, particularly downed logs, play an important role in the dynamics of forest ecosystem. Contribution of decaying wood to C and nutrient pools of forest soils depends on the tree species and degree of wood decay. However, the extent to which the downed logs affect the soil properties of temperate forests has rarely been evaluated. In this study, a mixed beech forest was selected in Liresar region of Mazandaran Province, northern Iran, to investigate if and how the presence of downed logs affected soil quality and function by comparing soils underneath degraded logs and nearby soils of the two dominant tree species(beech and hornbeam). We then explored how these effects occurred as downed logs decomposed by comparing the woods of both tree species at four degrees of decomposition. Degree of decay of downed logs was classified into four classes(DC1–DC4). Eight dead trees of each tree species were selected at the center of each sample plot. Three composite soil samples underneath each decaying log and 100 cm away from a decaying log were collected at two soil depths(0–15 and 15–30 cm) to analyze soil main physicochemical properties and microbial activity. The results revealed that downed logs affected soil physical(5% wetter than control soils), chemical(2% lower pH, 100% increase in organic C and total N in the case of hornbeam, and 2% increase in P), and biological characteristics(soil microbial respiration enhanced by 10%, and microbial biomass C 620 and 351.5 mg kg-1 and microbial biomass N 66.47 and 32.18 mg kg-1, respectively, in the cases of beech and hornbeam), thus resulting in significantly different soil microsites from those without downed logs. Presence of downed logs increased soil microbial activity and soil fertility as wood decayed. Thus, the presence of downed logs is an important factor influencing forest soils and should be taken into consideration in forest management practices.