Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas.An im...Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas.An important species for afforestation in dry environments of northern China,Mongolian pine(Pinus sylvestris var.mongolica Litv.)has recently exhibited growth decline and dieback on many sites,particularly pronounced in old-growth plantations.However,changes in response to drought stress by this species with age as well as the underlying mechanisms are poorly understood.In this study,tree-ring data and remotely sensed vegetation data were combined to investigate variations in growth at individual tree and stand scales for young(9-13 years)and aging(35-52 years)plantations of Mongolian pine in a water-limited area of northern China.A recent decline in tree-ring width in the older plantation also had lower values in satellited-derived normalized difference vegetation indices and normalized difference water indices relative to the younger plantations.In addition,all measured growth-related metrics were strongly correlated with the self-calibrating Palmer drought severity index during the growing season in the older plantation.Sensitivity of growth to drought of the older plantation might be attributed to more severe hydraulic limitations,as reflected by their lower sapwood-and leaf-specific hydraulic conductivities.Our study presents a comprehensive view on changes of growth with age by integrating multiple methods and provides an explanation from the perspective of plant hydraulics for growth decline with age.The results indicate that old-growth Mongolian pine plantations in water-limited environments may face increased growth declines under the context of climate warming and drying.展开更多
Aims Drought affected by atmosphere–ocean cycle is a dominant factor influencing tree radial growth of sandy Mongolian pine(Pinus sylvestris var.mongolica)and regional vegetation dynamics in Hulunbuir,China.However,h...Aims Drought affected by atmosphere–ocean cycle is a dominant factor influencing tree radial growth of sandy Mongolian pine(Pinus sylvestris var.mongolica)and regional vegetation dynamics in Hulunbuir,China.However,historical droughts and its correlations with tree radial growth and atmosphere–ocean cycle in this area have been little tested.Methods We developed tree-ring chronologies of Mongolian pine from Hulunbuir,Inner Mongolia,China and analyzed the correlations between tree-ring width index,the normalized difference vegetation index and Palmer drought severity index(PDSI),then developed a linear model to reconstruct the drought variability from 1829 to 2009.Long-term trends and its linkages with atmosphere–ocean cycle were performed by the power spectral,wavelet and teleconnection analysis.Important Findings The local moisture variations affected largely the regional vegetation dynamics and tree-ring growth of Mongolia pine in the forest–grassland transition.Using tree-ring width chronology of Mongolian pine,the reconstruction explains 49.2%of PDSI variance during their common data period(1951–2005).The reconstruction gives a broad-scale regional representation of PDSI in the Hulunbuir area,with drought occurrences in the 1850s,1900s,1920s,mid-1930s and at the turn of the 21st century.Comparisons with other treering drought reconstructions and historical records reveal some common drought periods and drying trends in recent decades at the northern margin zones of the East Asian summer monsoon(EASM).The drying trends in these zones occurred earlier than weakening of the EASM.A REDFIT spectral analysis shows significant peaks at 7.2,3.9,2.7–2.8,2.4 and 2.2 years with a 0.05 significance level,and 36.9,18.1 and 5.0 years with 0.1 significance level.Wavelet analysis also shows similar cycles.Drought variations in the study area significantly correlated with sea surface temperatures in the western tropical Pacific Ocean and middle and northern Indian Ocean,and the Pacific Decadal Oscillation and North Atlantic Oscillation.This suggests a possible linkage with the El Niño-Southern Oscillation,the EASM and the Westerlies.展开更多
Comparative analyses were conducted on the nutrient element content and returning amount of main fractional compositions of litter in Korean pine (KP), Mongolian Scots pine(MSP) and Dahurian larch (DL) plantations in ...Comparative analyses were conducted on the nutrient element content and returning amount of main fractional compositions of litter in Korean pine (KP), Mongolian Scots pine(MSP) and Dahurian larch (DL) plantations in Laoshan Plantation Experiment Station of Maoershan Experiment Forest Farm of Northeast Forestry University. The results are as follows: (1) The nutrient element content and returning amount in litter varies among different fractional compositions and tree species, the total returning amount of all nutrient elements and the returning amount of K, Ca, Mg, N and P are DL>MSP>KP, the returning amount of Cu is DL>KP>MSP, the returning amount of Fe and Mn are MSP>DL>KP, (2) To KP and DL plantations, the main nutrient element returned is dead needles; dead branches, bark scales and dead cones account for a little proportion; whereas to MSP plantation, besides dead needles,dead branches and bark scales also play an important role in the return of nutrient elements; (3)A little deal of dead leaves can provided a great deal of returning amount of nutrient elements.展开更多
The pine sawfly (Acantholyda posticalis Matsumura) is a serious pest of Pinus sylvestris; P. tabulaeformis and P. koraiensis. Chemical control has been generally applied, but caused a lot of problems. We first found F...The pine sawfly (Acantholyda posticalis Matsumura) is a serious pest of Pinus sylvestris; P. tabulaeformis and P. koraiensis. Chemical control has been generally applied, but caused a lot of problems. We first found Formica fukaii (new record in China). The ants nesting on Carex sp. preying on pine sawflics is an important predator. When nests are removed on purpose, the ant's behavior is normal and the nest are expanded. It is a dominant species and a natural enemy of pine sawfly in Nehe County.展开更多
Ectomycorrhizal(EM)networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer,seedling survival,internal cycling of nutrients,plant competition,and so on.To deeply their struc...Ectomycorrhizal(EM)networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer,seedling survival,internal cycling of nutrients,plant competition,and so on.To deeply their structure and function in ecosystems,we investigated the spatial patterns and nitrogen(N)transfer of EM networks usingN labelling technique in a Mongolian scotch pine(Pinus sylvestris var.mongolica Litv.)plantation in Northeastern China.In August 2011,four plots(20 × 20 m)were set up in the plantation.125 ml 5 at.%0.15 mol/LNHNOsolution was injected into soil at the center of each plot.Before and 2,6,30 and 215 days after theN application,needles(current year)of each pine were sampled along four 12 m sampling lines.Needle total N andN concentrations were analyzed.We observed needle N andN concentrations increased significantly over time afterN application,up to 31 and0.42%,respectively.There was no correlation between needle N concentration andN/N ratio(R2=0.40,n=5,P=0.156),while excess needle N concentration and excess needleN/N ratio were positively correlated across different time intervals(R~2=0.89,n=4,P\0.05),but deceased with time interval lengthening.NeedleN/N ratio increased with time,but it was not correlated with distance.NeedleN/N ratio was negative with distance before and 6th day and 30th day,positive with distance at 2nd day,but the trend was considerably weaker,their slop were close to zero.These results demonstrated that EM networks were ubiquitous and uniformly distributed in the Mongolian scotch pine plantation and a random network.We found N transfer efficiency was very high,absorbed N by EM network was transferred as wide as possible,we observed N uptake of plant had strong bias forN andN,namely N fractionation.Understanding the structure and function of EM networks in ecosystems may lead to a deeper understanding of ecological stability and evolution,and thus provide new theoretical approaches to improve conservation practices for the management of the Earth’s ecosystems.展开更多
Investigations were made in korean pine, mongolian scots pine and dahurian larch plantations in Laoshan Plantation Experiment Station of Maoershan Experiment Forest Farm of Northeast Forestry University. Data are tabu...Investigations were made in korean pine, mongolian scots pine and dahurian larch plantations in Laoshan Plantation Experiment Station of Maoershan Experiment Forest Farm of Northeast Forestry University. Data are tabulated on the amount and seasonal and annual nuctuations of fractional composition of the litter (conifer needles, branches, cones, bark scales, broad leaves) in the three plantations. The accounts of conifer needle branch and bark scale litter are as follows: korean pine: 71- 16%, 6. 23% and 7. 32%; mongolian scots pine: 43. 65%, 18. 52 % and 32. 12%; dahurian larch:90. 30%, 7. 83% and 1. 85%. There are certain broadleaf litter in dahurian larch and mongolian scots pine plantations (account for 7. 61% and 8. 92%respectively). The litter wither and fall concent ratively in autumn in dahurian larch plantation and scattered all year long in korean pine and mongolian scots pine plantations. Along with the increase of stand age, the absolute amount of litter tend to increase, the relative amount of main fractional compositions (conifer needle, branch and bark scale) in korean pine and mongolian Scots pine plantations maintain stead, whereas in dahurian larch plantation, the relative amount of conifer needle is decreased gradually and the relative amount of other fractional compositions are increased gradually.展开更多
The comparative result shows that the physical and mechanical properties of wood between white wood of Dahurian larch (Larix gmelini (Rupr.) Rupr.) and Mangolian scotch pine (Pinus cylvesthe var. mongolica) are differ...The comparative result shows that the physical and mechanical properties of wood between white wood of Dahurian larch (Larix gmelini (Rupr.) Rupr.) and Mangolian scotch pine (Pinus cylvesthe var. mongolica) are different Some differences are very conspicuous,(e. g. compressivc strength parallel to grain, modulus of elasticity in static bending, toughness and bending strength etc. ),and others are slightly conSPicuous or not conspicuous,(e.g. shrinkage, differential shrinkage and shearing strength parallel to grain etc.). The properties of white wood of Dahurian larch are suitable weight and soft texture, median strength,median shrinkage and good in worability, while which of Mongolian scotch pine are light and soft nearly very soft,weak strength, median shrinkage are good in workability. However, the white wood of Dahuran larch is superior to the Mongolian scotch pine in Strength-to-weight ratio.It is a valuable timber tree.展开更多
To estimate the mean value of surface soil water content rapidly,accurately,and nonintrusively,field investigations on soil electrical resistivity(SER)with the Yokogawa 324400 earth resistivity meter and the surface(0...To estimate the mean value of surface soil water content rapidly,accurately,and nonintrusively,field investigations on soil electrical resistivity(SER)with the Yokogawa 324400 earth resistivity meter and the surface(0-150 cm)soil water content(SWC)with time domain reflectometry(TDR),together with the abiotic factors including soil texture,structure. and salinity concentrations were conducted in the Mongolian pine(Pinus sylvestris var.mongolica)plantations on a sandy land.The measurement of SER was based on the 4-probe Wenner configuration method.Relationships between the values of SWC and SER were obtained based on analysis of the abiotic factors of the research site,which play a key role in affecting the soil electrical resistivity.Results indicate that the SER meter could be used to estimate the mean value of SWC in the Mongolian pine plantations on the sandy land during the growing seasons.The bulky nature of the equipment simplified the cumbersome measurements of soil water content with the general methods.It must be noted that the Wenner configuration method could only provide the mean values of the SWC,and the soil texture,structure, temperature,and solute concentrations influenced the SER and further affected the estimation of the SWC by the SER meter.Therefore,the results of this study could be applied on a sandy land during the growing seasons only.However, the SWC of other soil types also may be obtained according to the individual soil types using the procedures of this study.展开更多
The plantations of korean pine (Pinus koraensis) and scots pine (Pinus sylvesris var. mongolica) are mainly pure stands. Fires are gradually causing problems in these plantations and being paid much more attention rec...The plantations of korean pine (Pinus koraensis) and scots pine (Pinus sylvesris var. mongolica) are mainly pure stands. Fires are gradually causing problems in these plantations and being paid much more attention recently. Study on the influence of fire on trees and the adaptation to fire, therefore, is of great important to probe the fire ecological properties and the protection ways of these two species. The results are as follows: Both of the species are easily damaged by fire, but korean pine is more susceptible. In the same fire, korean pine is damaged more seriously than scots pine although they have the same size. Young individuals have low fire resistant capacity and can be damaged seriously, and older ones have strong fire resistance and can be damaged lightly. Up-hill fire makes a serious damage to the trees distributed in up-slopes with the reason of higher fire intensity. Down -hill fire makes a serious damage to the trees distributed in down-slopes with the reason of higher fire severity. The larger deocambium area in the tree bark is, the earlier tree growth after fire is. During the early growth stage, the damaged tree bark will Spill over much resin. The height of running resin is higher than that of dead cambium. Damaged trees sprout and grow more slowly and the length of leaves are shorter than these normal trees. The chiorophyll content of serious damaged trees is much higher than that of normal trees. The chiorophyll content of dying trees is 64. 29% higher than that of the contrast ones. Cell membrance penetrability of damaged trees is also higher than that of normal trees.展开更多
Mongolian pine (Pinus sylvestiris Linnaeus var. mongolica Litvinov) as a valuable conifer tree species has been broadly introduced to the sandy land areas in 揟hree North?regions (North, northwest and northeast of Chi...Mongolian pine (Pinus sylvestiris Linnaeus var. mongolica Litvinov) as a valuable conifer tree species has been broadly introduced to the sandy land areas in 揟hree North?regions (North, northwest and northeast of China), but many problems occurred in the earliest Mongolian pine plantations in Zhanggutai, Zhangwu County, Liaoning Province (ZZL). In order to clarify the reason, comprehensive investigations were carried out on differences in structure characteristics, growth processes and ecological factors between artificial stands (the first plantation established in ZZL in 1950s) and natural stands (the origin forests of the tree species in Honghuaerji, Inner Mongolia) on sandy land. The results showed that variation of diameter-class distributions in artificial stands and natural stands could be described by Weibull and Normal distribution models, respectively. Chapman-Richards growth model was employed to reconstruct the growth process of Mongolian pine based on the data from field investigation and stem analysis. The ages of maximum of relative growth rate and average growth rate of DBH, height, and volume of planted trees were 11, 22 years, 8, 15 years and 35, 59 years earlier than those of natural stand trees, respectively. In respect of the incremental acceleration of volume, the artificial and natural stands reached their maximum values at 14 years and 33 years respectively. The quantitative maturity ages of artificial stands and natural stands were 43 years and 102 years respectively. It was concluded that the life span of the Mongolian pine trees in natural stands was about 60 years longer than those in artificial stands. The differences mentioned above between artificial and natural Mongolian pine forests on sandy land were partially attributed to the drastic variations of ecological conditions such as latitude, temperature, precipitation, evaporation and height above sea level. Human beings' disturbances and higher density in plantation forest may be ascribed as additional reasons. Those results may be potentially useful for the management and afforestation of Mongolian pine plantations on sandy land in arid and semi-arid areas.展开更多
In order to examine the causes of degradation of Pinus sylvestris var.mongolica plantations on sandy land,the foliar concentrations of N,P,K and C were analyzed and compared between the field grown P.sylvestris var.mo...In order to examine the causes of degradation of Pinus sylvestris var.mongolica plantations on sandy land,the foliar concentrations of N,P,K and C were analyzed and compared between the field grown P.sylvestris var.mongolica trees from two provenances(natural forests and plantations).The results indicated that natural tree needles had lower N,P and C concentrations,and higher K concentrations than those of plantation tree needles.For plantation tree needles,ratios of N:P,P.K and N:K increased with tree age before 45 years old;but they were not clear for the natural tree needles.Compared with the conclusions reported on Pinus spp.,we found that the foliar N and P concentrations were in the optimal range for both natural and plantation tree needles.This result suggested that N or P might not be the absolute limit factors in plant nutrient for P sylvestris var.mongolica on sandy land.However,foliar K concentrations in both natural and plantation tree needles were much lower than those reported on Pinus spp.(〉4.80 g kg-1).The N:P ratio of natural needles was in the adequate ranges,but N:P ratio of plantation needles was out of the adequate ranges.These results indicated that there was a better balanced nutrition status in the natural forest than in the plantations.If only considering the foliar nutrient concentrations of P sylvestris var.mongolica from different provenances,it might be concluded that the degradation phenomenon of P.sylvestris var.mongolica plantations was not induced by nutrition deficiency of absolute nutrients of N and P,but might be induced by other mineral nutrients or by the effectiveness of N and P nutrients.The unbalanced nutrition status and relatively quick decomposition of needles in the plantations might also contribute to the degradation.展开更多
基金financially supported by the National Natural Science Foundation of China(31901093,32220103010,32192431,31722013)National Key R&D Program of China(2020YFA0608100,2022YFF1302505)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(ZDBS-LY-DQC019)。
文摘Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas.An important species for afforestation in dry environments of northern China,Mongolian pine(Pinus sylvestris var.mongolica Litv.)has recently exhibited growth decline and dieback on many sites,particularly pronounced in old-growth plantations.However,changes in response to drought stress by this species with age as well as the underlying mechanisms are poorly understood.In this study,tree-ring data and remotely sensed vegetation data were combined to investigate variations in growth at individual tree and stand scales for young(9-13 years)and aging(35-52 years)plantations of Mongolian pine in a water-limited area of northern China.A recent decline in tree-ring width in the older plantation also had lower values in satellited-derived normalized difference vegetation indices and normalized difference water indices relative to the younger plantations.In addition,all measured growth-related metrics were strongly correlated with the self-calibrating Palmer drought severity index during the growing season in the older plantation.Sensitivity of growth to drought of the older plantation might be attributed to more severe hydraulic limitations,as reflected by their lower sapwood-and leaf-specific hydraulic conductivities.Our study presents a comprehensive view on changes of growth with age by integrating multiple methods and provides an explanation from the perspective of plant hydraulics for growth decline with age.The results indicate that old-growth Mongolian pine plantations in water-limited environments may face increased growth declines under the context of climate warming and drying.
基金‘948’Project of State Forestry Administration China(2015-4-27)International S&T Cooperation Program of China(2015DFR31130)+1 种基金National Natural Science Foundation of China(41271033,41471029 and 41371500)The Lecture and Study Program for Outstanding Scholars from Home and Abroad(CAFYBB2011007).
文摘Aims Drought affected by atmosphere–ocean cycle is a dominant factor influencing tree radial growth of sandy Mongolian pine(Pinus sylvestris var.mongolica)and regional vegetation dynamics in Hulunbuir,China.However,historical droughts and its correlations with tree radial growth and atmosphere–ocean cycle in this area have been little tested.Methods We developed tree-ring chronologies of Mongolian pine from Hulunbuir,Inner Mongolia,China and analyzed the correlations between tree-ring width index,the normalized difference vegetation index and Palmer drought severity index(PDSI),then developed a linear model to reconstruct the drought variability from 1829 to 2009.Long-term trends and its linkages with atmosphere–ocean cycle were performed by the power spectral,wavelet and teleconnection analysis.Important Findings The local moisture variations affected largely the regional vegetation dynamics and tree-ring growth of Mongolia pine in the forest–grassland transition.Using tree-ring width chronology of Mongolian pine,the reconstruction explains 49.2%of PDSI variance during their common data period(1951–2005).The reconstruction gives a broad-scale regional representation of PDSI in the Hulunbuir area,with drought occurrences in the 1850s,1900s,1920s,mid-1930s and at the turn of the 21st century.Comparisons with other treering drought reconstructions and historical records reveal some common drought periods and drying trends in recent decades at the northern margin zones of the East Asian summer monsoon(EASM).The drying trends in these zones occurred earlier than weakening of the EASM.A REDFIT spectral analysis shows significant peaks at 7.2,3.9,2.7–2.8,2.4 and 2.2 years with a 0.05 significance level,and 36.9,18.1 and 5.0 years with 0.1 significance level.Wavelet analysis also shows similar cycles.Drought variations in the study area significantly correlated with sea surface temperatures in the western tropical Pacific Ocean and middle and northern Indian Ocean,and the Pacific Decadal Oscillation and North Atlantic Oscillation.This suggests a possible linkage with the El Niño-Southern Oscillation,the EASM and the Westerlies.
文摘Comparative analyses were conducted on the nutrient element content and returning amount of main fractional compositions of litter in Korean pine (KP), Mongolian Scots pine(MSP) and Dahurian larch (DL) plantations in Laoshan Plantation Experiment Station of Maoershan Experiment Forest Farm of Northeast Forestry University. The results are as follows: (1) The nutrient element content and returning amount in litter varies among different fractional compositions and tree species, the total returning amount of all nutrient elements and the returning amount of K, Ca, Mg, N and P are DL>MSP>KP, the returning amount of Cu is DL>KP>MSP, the returning amount of Fe and Mn are MSP>DL>KP, (2) To KP and DL plantations, the main nutrient element returned is dead needles; dead branches, bark scales and dead cones account for a little proportion; whereas to MSP plantation, besides dead needles,dead branches and bark scales also play an important role in the return of nutrient elements; (3)A little deal of dead leaves can provided a great deal of returning amount of nutrient elements.
文摘The pine sawfly (Acantholyda posticalis Matsumura) is a serious pest of Pinus sylvestris; P. tabulaeformis and P. koraiensis. Chemical control has been generally applied, but caused a lot of problems. We first found Formica fukaii (new record in China). The ants nesting on Carex sp. preying on pine sawflics is an important predator. When nests are removed on purpose, the ant's behavior is normal and the nest are expanded. It is a dominant species and a natural enemy of pine sawfly in Nehe County.
基金supported by National Natural Science Foundation of China(30830024)
文摘Ectomycorrhizal(EM)networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer,seedling survival,internal cycling of nutrients,plant competition,and so on.To deeply their structure and function in ecosystems,we investigated the spatial patterns and nitrogen(N)transfer of EM networks usingN labelling technique in a Mongolian scotch pine(Pinus sylvestris var.mongolica Litv.)plantation in Northeastern China.In August 2011,four plots(20 × 20 m)were set up in the plantation.125 ml 5 at.%0.15 mol/LNHNOsolution was injected into soil at the center of each plot.Before and 2,6,30 and 215 days after theN application,needles(current year)of each pine were sampled along four 12 m sampling lines.Needle total N andN concentrations were analyzed.We observed needle N andN concentrations increased significantly over time afterN application,up to 31 and0.42%,respectively.There was no correlation between needle N concentration andN/N ratio(R2=0.40,n=5,P=0.156),while excess needle N concentration and excess needleN/N ratio were positively correlated across different time intervals(R~2=0.89,n=4,P\0.05),but deceased with time interval lengthening.NeedleN/N ratio increased with time,but it was not correlated with distance.NeedleN/N ratio was negative with distance before and 6th day and 30th day,positive with distance at 2nd day,but the trend was considerably weaker,their slop were close to zero.These results demonstrated that EM networks were ubiquitous and uniformly distributed in the Mongolian scotch pine plantation and a random network.We found N transfer efficiency was very high,absorbed N by EM network was transferred as wide as possible,we observed N uptake of plant had strong bias forN andN,namely N fractionation.Understanding the structure and function of EM networks in ecosystems may lead to a deeper understanding of ecological stability and evolution,and thus provide new theoretical approaches to improve conservation practices for the management of the Earth’s ecosystems.
文摘Investigations were made in korean pine, mongolian scots pine and dahurian larch plantations in Laoshan Plantation Experiment Station of Maoershan Experiment Forest Farm of Northeast Forestry University. Data are tabulated on the amount and seasonal and annual nuctuations of fractional composition of the litter (conifer needles, branches, cones, bark scales, broad leaves) in the three plantations. The accounts of conifer needle branch and bark scale litter are as follows: korean pine: 71- 16%, 6. 23% and 7. 32%; mongolian scots pine: 43. 65%, 18. 52 % and 32. 12%; dahurian larch:90. 30%, 7. 83% and 1. 85%. There are certain broadleaf litter in dahurian larch and mongolian scots pine plantations (account for 7. 61% and 8. 92%respectively). The litter wither and fall concent ratively in autumn in dahurian larch plantation and scattered all year long in korean pine and mongolian scots pine plantations. Along with the increase of stand age, the absolute amount of litter tend to increase, the relative amount of main fractional compositions (conifer needle, branch and bark scale) in korean pine and mongolian Scots pine plantations maintain stead, whereas in dahurian larch plantation, the relative amount of conifer needle is decreased gradually and the relative amount of other fractional compositions are increased gradually.
文摘The comparative result shows that the physical and mechanical properties of wood between white wood of Dahurian larch (Larix gmelini (Rupr.) Rupr.) and Mangolian scotch pine (Pinus cylvesthe var. mongolica) are different Some differences are very conspicuous,(e. g. compressivc strength parallel to grain, modulus of elasticity in static bending, toughness and bending strength etc. ),and others are slightly conSPicuous or not conspicuous,(e.g. shrinkage, differential shrinkage and shearing strength parallel to grain etc.). The properties of white wood of Dahurian larch are suitable weight and soft texture, median strength,median shrinkage and good in worability, while which of Mongolian scotch pine are light and soft nearly very soft,weak strength, median shrinkage are good in workability. However, the white wood of Dahuran larch is superior to the Mongolian scotch pine in Strength-to-weight ratio.It is a valuable timber tree.
基金Project supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KZCX3-SW-418)the 100 Talents Program of the Chinese Academy of Sciences,China.
文摘To estimate the mean value of surface soil water content rapidly,accurately,and nonintrusively,field investigations on soil electrical resistivity(SER)with the Yokogawa 324400 earth resistivity meter and the surface(0-150 cm)soil water content(SWC)with time domain reflectometry(TDR),together with the abiotic factors including soil texture,structure. and salinity concentrations were conducted in the Mongolian pine(Pinus sylvestris var.mongolica)plantations on a sandy land.The measurement of SER was based on the 4-probe Wenner configuration method.Relationships between the values of SWC and SER were obtained based on analysis of the abiotic factors of the research site,which play a key role in affecting the soil electrical resistivity.Results indicate that the SER meter could be used to estimate the mean value of SWC in the Mongolian pine plantations on the sandy land during the growing seasons.The bulky nature of the equipment simplified the cumbersome measurements of soil water content with the general methods.It must be noted that the Wenner configuration method could only provide the mean values of the SWC,and the soil texture,structure, temperature,and solute concentrations influenced the SER and further affected the estimation of the SWC by the SER meter.Therefore,the results of this study could be applied on a sandy land during the growing seasons only.However, the SWC of other soil types also may be obtained according to the individual soil types using the procedures of this study.
文摘The plantations of korean pine (Pinus koraensis) and scots pine (Pinus sylvesris var. mongolica) are mainly pure stands. Fires are gradually causing problems in these plantations and being paid much more attention recently. Study on the influence of fire on trees and the adaptation to fire, therefore, is of great important to probe the fire ecological properties and the protection ways of these two species. The results are as follows: Both of the species are easily damaged by fire, but korean pine is more susceptible. In the same fire, korean pine is damaged more seriously than scots pine although they have the same size. Young individuals have low fire resistant capacity and can be damaged seriously, and older ones have strong fire resistance and can be damaged lightly. Up-hill fire makes a serious damage to the trees distributed in up-slopes with the reason of higher fire intensity. Down -hill fire makes a serious damage to the trees distributed in down-slopes with the reason of higher fire severity. The larger deocambium area in the tree bark is, the earlier tree growth after fire is. During the early growth stage, the damaged tree bark will Spill over much resin. The height of running resin is higher than that of dead cambium. Damaged trees sprout and grow more slowly and the length of leaves are shorter than these normal trees. The chiorophyll content of serious damaged trees is much higher than that of normal trees. The chiorophyll content of dying trees is 64. 29% higher than that of the contrast ones. Cell membrance penetrability of damaged trees is also higher than that of normal trees.
基金The research was supported by innovation research project of Chinese Academy of Sciences (KZCX3-SW-418) and by Nature Science Foundation of Liaoning Province (20021006).
文摘Mongolian pine (Pinus sylvestiris Linnaeus var. mongolica Litvinov) as a valuable conifer tree species has been broadly introduced to the sandy land areas in 揟hree North?regions (North, northwest and northeast of China), but many problems occurred in the earliest Mongolian pine plantations in Zhanggutai, Zhangwu County, Liaoning Province (ZZL). In order to clarify the reason, comprehensive investigations were carried out on differences in structure characteristics, growth processes and ecological factors between artificial stands (the first plantation established in ZZL in 1950s) and natural stands (the origin forests of the tree species in Honghuaerji, Inner Mongolia) on sandy land. The results showed that variation of diameter-class distributions in artificial stands and natural stands could be described by Weibull and Normal distribution models, respectively. Chapman-Richards growth model was employed to reconstruct the growth process of Mongolian pine based on the data from field investigation and stem analysis. The ages of maximum of relative growth rate and average growth rate of DBH, height, and volume of planted trees were 11, 22 years, 8, 15 years and 35, 59 years earlier than those of natural stand trees, respectively. In respect of the incremental acceleration of volume, the artificial and natural stands reached their maximum values at 14 years and 33 years respectively. The quantitative maturity ages of artificial stands and natural stands were 43 years and 102 years respectively. It was concluded that the life span of the Mongolian pine trees in natural stands was about 60 years longer than those in artificial stands. The differences mentioned above between artificial and natural Mongolian pine forests on sandy land were partially attributed to the drastic variations of ecological conditions such as latitude, temperature, precipitation, evaporation and height above sea level. Human beings' disturbances and higher density in plantation forest may be ascribed as additional reasons. Those results may be potentially useful for the management and afforestation of Mongolian pine plantations on sandy land in arid and semi-arid areas.
基金supported by Innovation Research Project of Chinese Academy of Sciences(KZCX3-SW-418)the 100 Young Researcher Project of Chinese Academy of Sciences.
文摘In order to examine the causes of degradation of Pinus sylvestris var.mongolica plantations on sandy land,the foliar concentrations of N,P,K and C were analyzed and compared between the field grown P.sylvestris var.mongolica trees from two provenances(natural forests and plantations).The results indicated that natural tree needles had lower N,P and C concentrations,and higher K concentrations than those of plantation tree needles.For plantation tree needles,ratios of N:P,P.K and N:K increased with tree age before 45 years old;but they were not clear for the natural tree needles.Compared with the conclusions reported on Pinus spp.,we found that the foliar N and P concentrations were in the optimal range for both natural and plantation tree needles.This result suggested that N or P might not be the absolute limit factors in plant nutrient for P sylvestris var.mongolica on sandy land.However,foliar K concentrations in both natural and plantation tree needles were much lower than those reported on Pinus spp.(〉4.80 g kg-1).The N:P ratio of natural needles was in the adequate ranges,but N:P ratio of plantation needles was out of the adequate ranges.These results indicated that there was a better balanced nutrition status in the natural forest than in the plantations.If only considering the foliar nutrient concentrations of P sylvestris var.mongolica from different provenances,it might be concluded that the degradation phenomenon of P.sylvestris var.mongolica plantations was not induced by nutrition deficiency of absolute nutrients of N and P,but might be induced by other mineral nutrients or by the effectiveness of N and P nutrients.The unbalanced nutrition status and relatively quick decomposition of needles in the plantations might also contribute to the degradation.
