[Objective] This study aimed to investigate the effects of nutrient and water stress on the secretion of organic acids from roots of two-year-old Larix olgensis. [Method] Different nutrient and water stress conditions...[Objective] This study aimed to investigate the effects of nutrient and water stress on the secretion of organic acids from roots of two-year-old Larix olgensis. [Method] Different nutrient and water stress conditions were designed to investi- gate the types and quantities of organic acids secreted from roots of two-year-old L. olgensis. [Result] Under nutrient and water stress, the types of organic acids secreted from roots of two-year-old L. olgensis increased, which varied with different stress levels. In addition, nutrient and water stress also increased the secretory vol- ume of organic acids from roots of two-year-old L. olgensis. The increment in total amount of organic acids reached the maximum under Level 1 (high stress). Among different types of organic acids, the increment in secretory volume of citric acid reached the maximum, followed by malic acid, while oxalic acid presented relatively small increment. Furthermore, the increment in secretory volume of these three organic acids all reached the maximum under Level 1. [Conclusion] The proportion of the secretory volume of each organic acid accounting for the total amount of organic acids varied slightly, but the overall order was unchanged.展开更多
Larix gmelinii var.principis-rupprechtii(Mayr.)Pilger is an important native tree species in North China with advantages of fast growth,straight trunk,and good wood properties.The multi-year and multi-site breeding re...Larix gmelinii var.principis-rupprechtii(Mayr.)Pilger is an important native tree species in North China with advantages of fast growth,straight trunk,and good wood properties.The multi-year and multi-site breeding research of families of the species has not been reported previously.Based on diameter at breast height(DBH),height and volume of 25 families on four experimental sites,we calculated variance components,genetic parameters,juvenile and mature trait correlations and made genotype main effect plus genotype×environment interaction effect(GGE)biplot based on the breeding values estimated using the method of best linear unbiased prediction(BLUP).Compared with height,DBH and volume had higher heritability and larger variation coefficients,making them the more suitable traits for family selection and evaluation.Based on these,GGE biplots containing 20 combinations of site×age were drawn using data at 13 to 17 years when the interactions between family and location were strong.Test sites classifications based on DBH,and volume were inconsistent,with two categories for DBH and one for volume.The Guyuan site was the most suitable with strong discriminating ability,high representativeness and stability among tree ages.Integrating the ranking results of DBH and volume,families 66,76,82 and 111 were high-yielding and stable,families 78 and96 were high-yielding with above average stability,families72 and 79 were high-yielding with below average stability,whereas stability of family 100 was inconsistent between DBH and volume.Early selection based on DBH was convenient and reliable,and can be made at seven years.This study provides support for the selection of Larix gmelinii var.principis-rupprechtii families in Hebei province and an example for the application of stem analysis data from multiple sites in tree breeding.展开更多
Nutrient retranslocation in trees is important in nutrient budgets and energy flows in forest ecosystems. We investigated nutrient retranslocation in the fine roots of a Manchurian Ash (Fraxinus mandshurica) and a L...Nutrient retranslocation in trees is important in nutrient budgets and energy flows in forest ecosystems. We investigated nutrient retranslocation in the fine roots of a Manchurian Ash (Fraxinus mandshurica) and a Larch (Larix olgensis) plantation in northeastern China. Nutrient retranslocation in the fine roots was investigated using three methods, specifically, nutrient concentration, the ratio of Ca to other elements (Ca/other elements ratio) and nutrient content. The method based on nutrient content proved most suitable when investigating nutrient retranslocation from fine roots of the two species. The nutrient-content-based method showed that there were retranslocations of N, P, K and Mg from the fine roots of Manchurian Ash, with retranslocation efficiencies of 13, 25, 65, and 38 %, respectively, whereas there were no Ca retranslocations. There were retranslocations of N, P, K, Ca and Mg from the fine roots of Larch, with retranslocation efficiencies of 31, 40, 52, 23 and 25 %, respectively.展开更多
Research has indicated that simple forest eco-system composition,structure and diversity have uncompli-cated community relationships and insufficient pest control capabilities.To investigate changing characteristics o...Research has indicated that simple forest eco-system composition,structure and diversity have uncompli-cated community relationships and insufficient pest control capabilities.To investigate changing characteristics of plant and insect communities in under pest outbreaks in Larix principis-rupprechtii plantations,the research areas were defined as mature(48–50 years)and young(24–29 years)infested stands along with healthy stands.The results show a reduction in the complexity and diversity of plant communi-ties and herbaceous plant guilds(polycultures of beneficial plants)and the complexity and dominance of insect com-munities,especially natural insect enemies.The results also show the relative simplicity of the main factors of commu-nity change and development that represent the characteris-tics of pest outbreaks in L.principis-rupprechtii plantations.The complexity and diversity of plant communities,particu-larly herbaceous plant guilds play a fundamental role in the regulation and development in forest ecosystems.展开更多
Through 5 years of phenological observations on Larix principis-rupprechtii Mayr. in primary seed orchard and studies on population and individuals of clones, the annual periodic phenological laws were revealed and th...Through 5 years of phenological observations on Larix principis-rupprechtii Mayr. in primary seed orchard and studies on population and individuals of clones, the annual periodic phenological laws were revealed and the annual phe-nological periodic table was drawn up. The correlation between various phenophases, the air temperature and active accumu-lated temperature were analyzed and expounded. The authors also analyzed the similarities and differences of phenophases among clonal individuals as well as the blooming properties of male and female flowers at the same time. This study could pro-vide theoretical reference for working out the production plan of improved varieties and other management measures in seed orchard of Larix principis-rupprechtii.展开更多
The spatial distribution of standing fine roots in tree rows of different species in a 12-year-old mixed stand of ash (Fraxinus mandshurica Rupr.) and larch (Larix olgensis Henry) was studied by soil core sampling in ...The spatial distribution of standing fine roots in tree rows of different species in a 12-year-old mixed stand of ash (Fraxinus mandshurica Rupr.) and larch (Larix olgensis Henry) was studied by soil core sampling in early spring, 2001. It is found that ash and larch differ greatly in their belowground biomass distribution. Ash has much higher fine root biomass density in the soil than larch at stand level (with the max value of 4442.3 vs. 2234.9 gm-3). Both tree species deployed more fine roots in their neighboring zone, suggesting a less intensive competition between roots of the two species. Both fine root biomass density and root length density of ash in the zone between larch tree rows are greater than that of larch in zone between ash tree rows, indicating that ash is more powerful than larch in belowground competition. The spatial distribution feature of roots favors the growth of ash in the mixed stand.展开更多
Larix principis-rupprechtii Mayr is a dominant species in coniferous forests of North China.However,early selection of L.principis-rupprechtii for growth traits is poorly characterised.To explore the optimal selection...Larix principis-rupprechtii Mayr is a dominant species in coniferous forests of North China.However,early selection of L.principis-rupprechtii for growth traits is poorly characterised.To explore the optimal selection age for this species,heights(HT)and diameters at breast(DBH)of 40 half-sib families were measured at ages 3,12,22,and 28 years in a progeny test population established in the town of Kangjiahui,Shanxi Province.Age trends in heritability,age–age genetic correlations,and early selection efficiency for height and DBH were analysed.The individual heritability of these growth traits varied over time,and maximized at different ages(0.55 at age 12 for HT and 0.48 at age 28 for DBH).The age–age genetic correlations were always positive,and the majority were high(0.790–0.953)between the juvenile and mature ages for HT and DBH.For the same pairs of measurements,HT demonstrated higher age–age genetic correlations than DBH,and both age–age genetic correlation data sets were described well by the linear relationship with the logarithm of the age ratio(r2[0.90).The regression slope for DBH was lower than that for HT.Based on the early selection efficiency estimates,the optimal selection age could be as early as age 6 for DBH and 8–9 years for HT.The results of this study provide information that can be used to assist early selection practices in L.principis-rupprechtii improvement programs in Shanxi Province.展开更多
Relationships between stem growth and climatic and edaphic factors,notably air temperatures and soil moisture for different slopes,are not completely understood.Stem radial variations were monitored at the bottom and ...Relationships between stem growth and climatic and edaphic factors,notably air temperatures and soil moisture for different slopes,are not completely understood.Stem radial variations were monitored at the bottom and top slope positions in a Larix principis-rupprechtii plantation during the 2017 and 2018 growing seasons.Total precipitation during the growing season in 2017 and 2018 was 566 mm and 728 mm,respectively.Stem contractions typically occurred after mid-morning followed by swelling in the late afternoon in both plots,reflecting the diurnal cycle of water uptake and loss.Trees at the two locations showed the same growth initiation(mid-May)because of the small differences in air and soil temperatures.There were no significant differences in cumulative stem radial growth between the bottom plot(1.57±0.34 mm)and the top plot(1.55±0.26 mm)in 2018.However,in 2017,the main growth period of the bottom plot ceased 17 days earlier than in the top plot,while cumulative seasonal growth of the bottom plot(1.08±0.25 mm)was significantly less than the top plot(1.54±0.43 mm).Maximum daily stem shrinkage was positively correlated with air and soil temperatures,solar radiation,vapor pressure deficits,and negatively correlated with volumetric soil moisture content.The maximum daily shrinkage reflected transpiration rates as affected by environmental factors.Daily radial stem increment was correlated with precipitation and volumetric soil moisture in both years,but with air temperatures only in 2017.The seasonal growth of L.principis-rupprechtii Mayr thus shows interannual dynamics,while precipitation constitutes a key driving factor.展开更多
Leaf area index(LAI) is a key factor that determines a forest ecosystem's net primary production and energy exchange between the atmosphere and land surfaces.LAI can be measured in many ways, but there has been li...Leaf area index(LAI) is a key factor that determines a forest ecosystem's net primary production and energy exchange between the atmosphere and land surfaces.LAI can be measured in many ways, but there has been little research to compare LAI estimated by different methods. In this study, we compared the LAI results from two different approaches, i.e., the dimidiate pixel model(DPM) and an empirical statistic model(ESM) using ZY-3 high-accuracy satellite images validated by field data. We explored the relationship of LAI of Larix principis-rupprechtii Mayr plantations with topographic conditions. The results show that DPM improves the simulation of LAI(r = 0.86,RMSE = 0.57) compared with ESM(r = 0.62, RMSE =0.79). We further concluded that elevation and slope significantly affect the distribution of LAI. The maximum peak of LAI appeared at an aspect of east and southeast at an elevation of 1700–2000 m. Our results suggest that ZY-3 can satisfy the needs of quantitative monitoring of leaf area indices in small-scale catchment areas. DPM provides a simple and accurate method to obtain forest vegetation parameters in the case of non-ground measurement points.展开更多
In this study,three different ages of Larix principis-rupprechtii forests in 5,10 and 20 years were selected as the research objects,and the changes in soil nutrient and soil enzyme activities in different growth stag...In this study,three different ages of Larix principis-rupprechtii forests in 5,10 and 20 years were selected as the research objects,and the changes in soil nutrient and soil enzyme activities in different growth stages were analyzed. The results showed that the contents of organic matter and available phosphorus in the soil of different growth stages showed a significant downward trend with the increase of soil depth.For different forest ages in the same soil layer,the soil available phosphorus content declined with the increase of the forest age. The organic matter content of 40-60 cm in 20 years of forest age was the lowest in July,which was 4. 17 g/kg,significantly lower than that in other soil layers. Besides,the soil available phosphorus content of 5 years of forest age reached the maximum in July,with an average of 4. 44 mg/kg,which was higher than the available phosphorus content in soil in May and September,but the difference between the three months was not significant. The changes in ammonium nitrogen and nitrate nitrogen content in soil with different forest ages were consistent with the changes in the soil depth,showing a downward trend. In the new leaf stage,the ammonium nitrogen content of the L. principis-rupprechtii forest land in5 years of age at 20-40 and 40-60 cm of the soil depth was 13. 47 and 9. 09 mg/kg,respectively,which was 46. 9% and 64. 2% lower than that at 0-20 cm( 25. 36 mg/kg) of the soil depth. The soil nitrate nitrogen content of 20 years of forest age was 19. 24 mg/kg,which was25. 8% lower than that of 10 years of forest age,showing significant difference( P < 0. 05). In addition,with the increase of the age of L. principis-rupprechtii,soil catalase( CAT),alkaline phosphatase( ALP) and urease( Ure) decreased,and the decline of ALP was slow,while CAT and Ure decreased significantly. In summary,it is concluded that the soil fertility of forest land declined with the increase of forest age on the basis of change trend of soil nutrient and soil enzyme activity in the surveyed forest age.展开更多
Background:Stem CO_(2) efflux(E_(S))plays a critical role in the carbon budget of forest ecosystems.Thinning is a core practice for sustainable management of plantations.It is therefore necessary and urgent to study t...Background:Stem CO_(2) efflux(E_(S))plays a critical role in the carbon budget of forest ecosystems.Thinning is a core practice for sustainable management of plantations.It is therefore necessary and urgent to study the effect and mechanism of thinning intensity(TI)on E_(S).Methods:In this study,five TIs were applied in Larix principis-rupprechtii Mayr 21-,25-,and 41-year-old stands in North China in 2010.Portable infrared gas analyzer(Li-8100 A)was used to measure ES and its association with environmental factors at monthly intervals from May to October in 2013 to 2015.In addition,nutrients,wood structure and nonstructural carbon(NSC)data were measured in August 2016.Results:The results show that ES increased with increasing TI.The maximum ES values occurred at a TI of 35%(3.29,4.57 and 2.98μmol·m^(-2)·s^(-1))and were 1.54-,1.94-and 2.89-fold greater than the minimum E_(S) value in the CK stands(2.14,2.35 and 1.03μmol·m^(-2)·s^(-1))in July for the 21-,25-and 41-year-old forests,respectively.The E_(S) of the trees in low-density stands was more sensitive to temperature than that of the trees in high-density stands.Soluble sugars(SS)and temperature are the main factors affecting ES.When the stand density is low enough as 41-year-old L.principis-rupprechtii forests with TI 35%,bark thickness(BT)and humidity should be considered in addition to air temperature(T_(a)),wood temperature(T_(w)),sapwood width(SW),nitrogen concentration(N)and SS in the evaluation of ES.If a change in stand density is ignored,the CO_(2) released from individual 21-,25-and 41-year-old trees could be underestimated by 168.89%,101.94% and 200.49%,respectively.CO_(2) release was estimated based on the stem equation in combination with the factors influencing ES for reference.Conclusions:We suggest that it is not sufficient to conventional models which quantify ES only by temperature and that incorporating the associated drivers(e.g.density,SS,SW and N)based on stand density into conventional models can improve the accuracy of ES estimates.展开更多
Prince Rupprecht’s larch(Larix principis-rupprechtii Mayr.),a deciduous conifer,widely grows in middle and high elevations of Northern China.Its natural distribution has sharply decreased and has become fragmented,wh...Prince Rupprecht’s larch(Larix principis-rupprechtii Mayr.),a deciduous conifer,widely grows in middle and high elevations of Northern China.Its natural distribution has sharply decreased and has become fragmented,which may have resulted in the loss of genetic variation.In this study,ten natural populations across the entire range of this species were analyzed using amplifi ed fragment length polymorphism markers.A total of 309 loci were detected from 225 individuals of these populations,of which 261(84.5%)were polymorphic.At the species level,the genetic diversity was high(average of the Nei’s genetic diversity H e=0.2602,and Shannon’s information index I=0.3967).The results of molecular variance analysis showed that 90.71%of the genetic diversity occurred within populations.The genetic diff erentiation among populations was moderate as a whole(F ST=0.0929,G ST=0.1510),which is consistent with the moderate level of gene fl ow among populations(N m=2.8116).Based on the unweighted pair group method with arithmetic mean and STRU CTU RE analysis,these populations were grouped into three genetically distinct clusters.The degree of inter-population diff erentiation(G ST=0.1338)for the south group was larger than that for the north group(G ST=0.0915).There was a signifi cant correlation between genetic distance and geographic distance across the species range(r=0.316,P<0.05).Genetic diversity was signifi-cantly associated with longitude but not elevation or climatic factors.The populations with high genetic diversity from each cluster are therefore recommended for future conservation and management of this species.展开更多
SSH was used to analyze gene transactivation during root formation of Larix cuttings. Two subtractive cDNA libraries were constructed from clone 31-6 as tester or driver and clone 15-4 as driver or tester. The SSH PCR...SSH was used to analyze gene transactivation during root formation of Larix cuttings. Two subtractive cDNA libraries were constructed from clone 31-6 as tester or driver and clone 15-4 as driver or tester. The SSH PCR products from the libraries were cloned into a pGEM-T easy vector and after PCR and dot blot analysis, positive clones were selected, sequenced and compared to the database in GenBank with BLASTX. The results of a sequence assembly in two libraries show that 521 UniEST (expressed sequence tag) were obtained. These 521 UniEST belong to metabolism, signal pathways, transport, resistance, developmental processes, local- ization, unknown proteins and "no hits found". All of these suggest that subtractive cDNA libraries during root formation of Larix cuttings were constructed successfully.展开更多
Extreme climate has increasingly led to negative impacts on forest ecosystems globally,especially in semiarid areas where forest ecosystems are more vulnerable.However,it is poorly understood how tree growth is affect...Extreme climate has increasingly led to negative impacts on forest ecosystems globally,especially in semiarid areas where forest ecosystems are more vulnerable.However,it is poorly understood how tree growth is affected by different drought events.In 2006–2009,the larch plantations in the semiarid areas of Northwest China were negatively affected by four consecutive dry years,which was a very rare phenomenon that may occur frequently under future climate warming.In this study,we analyzed the effect of these consecutive dry years on tree growth based on the data of the tree rings in the dominant layer of the forest canopy on a larch plantation.We found that the tree-ring width index(RWI)in dry years was lower than that in normal years,and it experienced a rapidly decreasing trend from 2006 to 2009(slope=-0.139 year^(-1),r=-0.94)due to water supply deficits in those dry years.Drought induced legacy effects of tree growth reduction,and consecutive dry years corresponded with greater growth reductions and legacy effects.Growth reductions and legacy effects were significantly stronger in the third and fourth consecutive dry years than that of single dry year(p<0.05),which might have been due to the cumulative stress caused by consecutive dry years.Our results showed that larch trees experienced greater tree growth reduction due to consecutive dry years and their legacy effect,and the trees had lower recovery rates after consecutive dry years.Our results highlight that consecutive dry years pose a new threat to plantations under climate warming,and thus,the effect of climate extremes on tree growth should be considered in growth models in semiarid areas.展开更多
Horizontal and veftical distributions of fine root abundance (mass per unit ground surface arca) were investi-gated in a densely planted larch - ash -stripe - mixed tbrest on dark broxvn forest soil in northeast China...Horizontal and veftical distributions of fine root abundance (mass per unit ground surface arca) were investi-gated in a densely planted larch - ash -stripe - mixed tbrest on dark broxvn forest soil in northeast China. There was evidencefor some degree of below-ground niche partitioning (or differentiation) betmpen the two species in hoth the horizontal andvertical directions. The ash fine roots largely penetrated into the larch belt (larch Sub-community) in surttrce soil (0-20 cm),indicating a possible inductive effect of larch ecological field on ash roots, while the penetration of larch tine roots into ashbelt (ash sub-community) was much restricted- which reflected a negative influence of ash ccological tield on Iarch roots. Inthe vertical direction of marginal soil the ash tine roots were mainly distributed in topsoil with a vertical gradient similar tothat as in the internal ash sub-community. but the larch fine roots were relatively compelled to deepcr soil layers by the com-petition (or exclusion) of marginal ash trees. All the dit1brences or complemcntarity wcre considered to the result of inter-specitic competition, which was important to the coexistence of the two tbrest species and the sustainability of mixed planta-tion.展开更多
Fine root turnover plays a key role in carbon (C) budgets and nutrients cycles in forest ecosystems. However, the difference between branch-order-based and diameter-based approaches in estimating fine root turnover ...Fine root turnover plays a key role in carbon (C) budgets and nutrients cycles in forest ecosystems. However, the difference between branch-order-based and diameter-based approaches in estimating fine root turnover is still unclear. We studied root biomass turnover based on multiplying root standing biomass by turnover rate (inverse of median root longevity) in two Chinese temperate tree species, Fraxinus mand- shurica Rupr. and Larix gmelinii Rupr. The minirhizotron (MR) tech- nique was used to estimate longevities for first and second order roots, and total roots (R,o,al) apparent on the MR tube surface. The correspond- ing biomass for each root group was estimated by soil monolith. The difference in biomass turnover between Rtotal and the sum of the first and second order roots was used to represent the discrepancy between di- ameter- and order-based approaches. First order roots had shorter life spans and higher biomass turnover rates than the second order roots in both species. Biomass turnover estimated by the order-based method for F. mandshurica and L. gmelinii were 155.4 g.m2.aland 158.9 g.m2.a-1, respectively, in comparison with 99.5 g.m^-2-a^-1 and 117.7 g.m^-2.a^-1 estimated by the diameter-based method, indicating that the diameter-based approach underestimated biomass turnover. The most probable reason was that the order-based method enhanced separation of the heterogeneous root population into relatively homogenous root groups with varying turnover rates. We conclude that separating fine root pool into different branch orders can improve the accuracy of estimates for fine root turnover, as well as the understanding of the belowground C allocation and nutrient cycling at ecosystem level.展开更多
基金Supported by National Natural Science Foundation of China(31370613)Major State Basic Research Development Program of China(973 Program)(2011CB403202)+1 种基金Project of General Administration of Quality Supervision,Inspection and Quarantine of China(2009IK177)Fundamental Research Fund for the Central Universities(DL12CA01)~~
文摘[Objective] This study aimed to investigate the effects of nutrient and water stress on the secretion of organic acids from roots of two-year-old Larix olgensis. [Method] Different nutrient and water stress conditions were designed to investi- gate the types and quantities of organic acids secreted from roots of two-year-old L. olgensis. [Result] Under nutrient and water stress, the types of organic acids secreted from roots of two-year-old L. olgensis increased, which varied with different stress levels. In addition, nutrient and water stress also increased the secretory vol- ume of organic acids from roots of two-year-old L. olgensis. The increment in total amount of organic acids reached the maximum under Level 1 (high stress). Among different types of organic acids, the increment in secretory volume of citric acid reached the maximum, followed by malic acid, while oxalic acid presented relatively small increment. Furthermore, the increment in secretory volume of these three organic acids all reached the maximum under Level 1. [Conclusion] The proportion of the secretory volume of each organic acid accounting for the total amount of organic acids varied slightly, but the overall order was unchanged.
基金supported by the Key Research and Development Program of Hebei Province[20326333D]Science and Technology Promotion Demonstration Project of forestry and grassland in Hebei Province[Hebei TG[2019]001]Science and Technology Promotion Demonstration Project of forestry and grassland in Hebei Province[Hebei TG[2020]013]。
文摘Larix gmelinii var.principis-rupprechtii(Mayr.)Pilger is an important native tree species in North China with advantages of fast growth,straight trunk,and good wood properties.The multi-year and multi-site breeding research of families of the species has not been reported previously.Based on diameter at breast height(DBH),height and volume of 25 families on four experimental sites,we calculated variance components,genetic parameters,juvenile and mature trait correlations and made genotype main effect plus genotype×environment interaction effect(GGE)biplot based on the breeding values estimated using the method of best linear unbiased prediction(BLUP).Compared with height,DBH and volume had higher heritability and larger variation coefficients,making them the more suitable traits for family selection and evaluation.Based on these,GGE biplots containing 20 combinations of site×age were drawn using data at 13 to 17 years when the interactions between family and location were strong.Test sites classifications based on DBH,and volume were inconsistent,with two categories for DBH and one for volume.The Guyuan site was the most suitable with strong discriminating ability,high representativeness and stability among tree ages.Integrating the ranking results of DBH and volume,families 66,76,82 and 111 were high-yielding and stable,families 78 and96 were high-yielding with above average stability,families72 and 79 were high-yielding with below average stability,whereas stability of family 100 was inconsistent between DBH and volume.Early selection based on DBH was convenient and reliable,and can be made at seven years.This study provides support for the selection of Larix gmelinii var.principis-rupprechtii families in Hebei province and an example for the application of stem analysis data from multiple sites in tree breeding.
基金supported by the National Key Technology Research and Development Program(2012BAD21B0202-02)the Natural Science Foundation of Heilongjiang Province of China(C201340)the assisted project by Heilong Jiang Postdoctoral Funds for Scientific Research Initiation(LBH-Q13006)
文摘Nutrient retranslocation in trees is important in nutrient budgets and energy flows in forest ecosystems. We investigated nutrient retranslocation in the fine roots of a Manchurian Ash (Fraxinus mandshurica) and a Larch (Larix olgensis) plantation in northeastern China. Nutrient retranslocation in the fine roots was investigated using three methods, specifically, nutrient concentration, the ratio of Ca to other elements (Ca/other elements ratio) and nutrient content. The method based on nutrient content proved most suitable when investigating nutrient retranslocation from fine roots of the two species. The nutrient-content-based method showed that there were retranslocations of N, P, K and Mg from the fine roots of Manchurian Ash, with retranslocation efficiencies of 13, 25, 65, and 38 %, respectively, whereas there were no Ca retranslocations. There were retranslocations of N, P, K, Ca and Mg from the fine roots of Larch, with retranslocation efficiencies of 31, 40, 52, 23 and 25 %, respectively.
文摘Research has indicated that simple forest eco-system composition,structure and diversity have uncompli-cated community relationships and insufficient pest control capabilities.To investigate changing characteristics of plant and insect communities in under pest outbreaks in Larix principis-rupprechtii plantations,the research areas were defined as mature(48–50 years)and young(24–29 years)infested stands along with healthy stands.The results show a reduction in the complexity and diversity of plant communi-ties and herbaceous plant guilds(polycultures of beneficial plants)and the complexity and dominance of insect com-munities,especially natural insect enemies.The results also show the relative simplicity of the main factors of commu-nity change and development that represent the characteris-tics of pest outbreaks in L.principis-rupprechtii plantations.The complexity and diversity of plant communities,particu-larly herbaceous plant guilds play a fundamental role in the regulation and development in forest ecosystems.
文摘Through 5 years of phenological observations on Larix principis-rupprechtii Mayr. in primary seed orchard and studies on population and individuals of clones, the annual periodic phenological laws were revealed and the annual phe-nological periodic table was drawn up. The correlation between various phenophases, the air temperature and active accumu-lated temperature were analyzed and expounded. The authors also analyzed the similarities and differences of phenophases among clonal individuals as well as the blooming properties of male and female flowers at the same time. This study could pro-vide theoretical reference for working out the production plan of improved varieties and other management measures in seed orchard of Larix principis-rupprechtii.
基金This study was supported by National Natural Science Foundation of China (Grant No. 30130160) and the Quick Response of Basic Research Supporting Program (Grant No.2102)
文摘The spatial distribution of standing fine roots in tree rows of different species in a 12-year-old mixed stand of ash (Fraxinus mandshurica Rupr.) and larch (Larix olgensis Henry) was studied by soil core sampling in early spring, 2001. It is found that ash and larch differ greatly in their belowground biomass distribution. Ash has much higher fine root biomass density in the soil than larch at stand level (with the max value of 4442.3 vs. 2234.9 gm-3). Both tree species deployed more fine roots in their neighboring zone, suggesting a less intensive competition between roots of the two species. Both fine root biomass density and root length density of ash in the zone between larch tree rows are greater than that of larch in zone between ash tree rows, indicating that ash is more powerful than larch in belowground competition. The spatial distribution feature of roots favors the growth of ash in the mixed stand.
基金supported by National Key R&D Program of China(2017YFD0600404-1)Medium and Long Scientific Research Project for Young Teachers in Beijing Forestry University(2015ZCQ-SW-02)+2 种基金the Project of National Natural Science Foundation of China(31370658)Program for Changjiang Scholars and Innovative Research Team in University(IRT13047)the Project of Beijing Gardening and Greening Bureau(CEG-2016-01)
文摘Larix principis-rupprechtii Mayr is a dominant species in coniferous forests of North China.However,early selection of L.principis-rupprechtii for growth traits is poorly characterised.To explore the optimal selection age for this species,heights(HT)and diameters at breast(DBH)of 40 half-sib families were measured at ages 3,12,22,and 28 years in a progeny test population established in the town of Kangjiahui,Shanxi Province.Age trends in heritability,age–age genetic correlations,and early selection efficiency for height and DBH were analysed.The individual heritability of these growth traits varied over time,and maximized at different ages(0.55 at age 12 for HT and 0.48 at age 28 for DBH).The age–age genetic correlations were always positive,and the majority were high(0.790–0.953)between the juvenile and mature ages for HT and DBH.For the same pairs of measurements,HT demonstrated higher age–age genetic correlations than DBH,and both age–age genetic correlation data sets were described well by the linear relationship with the logarithm of the age ratio(r2[0.90).The regression slope for DBH was lower than that for HT.Based on the early selection efficiency estimates,the optimal selection age could be as early as age 6 for DBH and 8–9 years for HT.The results of this study provide information that can be used to assist early selection practices in L.principis-rupprechtii improvement programs in Shanxi Province.
基金supported by the Ningxia Hui Autonomous Region(QCYL-2018-12)the National Key Research and Development Program of China(2016YFC0501603,2017YFC0504602)the National Natural Science Foundation of China(41671025).
文摘Relationships between stem growth and climatic and edaphic factors,notably air temperatures and soil moisture for different slopes,are not completely understood.Stem radial variations were monitored at the bottom and top slope positions in a Larix principis-rupprechtii plantation during the 2017 and 2018 growing seasons.Total precipitation during the growing season in 2017 and 2018 was 566 mm and 728 mm,respectively.Stem contractions typically occurred after mid-morning followed by swelling in the late afternoon in both plots,reflecting the diurnal cycle of water uptake and loss.Trees at the two locations showed the same growth initiation(mid-May)because of the small differences in air and soil temperatures.There were no significant differences in cumulative stem radial growth between the bottom plot(1.57±0.34 mm)and the top plot(1.55±0.26 mm)in 2018.However,in 2017,the main growth period of the bottom plot ceased 17 days earlier than in the top plot,while cumulative seasonal growth of the bottom plot(1.08±0.25 mm)was significantly less than the top plot(1.54±0.43 mm).Maximum daily stem shrinkage was positively correlated with air and soil temperatures,solar radiation,vapor pressure deficits,and negatively correlated with volumetric soil moisture content.The maximum daily shrinkage reflected transpiration rates as affected by environmental factors.Daily radial stem increment was correlated with precipitation and volumetric soil moisture in both years,but with air temperatures only in 2017.The seasonal growth of L.principis-rupprechtii Mayr thus shows interannual dynamics,while precipitation constitutes a key driving factor.
基金supported by the National Forestry Public Welfare Professional Scientific Research Project(No.201404213)the National Key Research and Development Program of China(No.2016YFD0600205)
文摘Leaf area index(LAI) is a key factor that determines a forest ecosystem's net primary production and energy exchange between the atmosphere and land surfaces.LAI can be measured in many ways, but there has been little research to compare LAI estimated by different methods. In this study, we compared the LAI results from two different approaches, i.e., the dimidiate pixel model(DPM) and an empirical statistic model(ESM) using ZY-3 high-accuracy satellite images validated by field data. We explored the relationship of LAI of Larix principis-rupprechtii Mayr plantations with topographic conditions. The results show that DPM improves the simulation of LAI(r = 0.86,RMSE = 0.57) compared with ESM(r = 0.62, RMSE =0.79). We further concluded that elevation and slope significantly affect the distribution of LAI. The maximum peak of LAI appeared at an aspect of east and southeast at an elevation of 1700–2000 m. Our results suggest that ZY-3 can satisfy the needs of quantitative monitoring of leaf area indices in small-scale catchment areas. DPM provides a simple and accurate method to obtain forest vegetation parameters in the case of non-ground measurement points.
文摘In this study,three different ages of Larix principis-rupprechtii forests in 5,10 and 20 years were selected as the research objects,and the changes in soil nutrient and soil enzyme activities in different growth stages were analyzed. The results showed that the contents of organic matter and available phosphorus in the soil of different growth stages showed a significant downward trend with the increase of soil depth.For different forest ages in the same soil layer,the soil available phosphorus content declined with the increase of the forest age. The organic matter content of 40-60 cm in 20 years of forest age was the lowest in July,which was 4. 17 g/kg,significantly lower than that in other soil layers. Besides,the soil available phosphorus content of 5 years of forest age reached the maximum in July,with an average of 4. 44 mg/kg,which was higher than the available phosphorus content in soil in May and September,but the difference between the three months was not significant. The changes in ammonium nitrogen and nitrate nitrogen content in soil with different forest ages were consistent with the changes in the soil depth,showing a downward trend. In the new leaf stage,the ammonium nitrogen content of the L. principis-rupprechtii forest land in5 years of age at 20-40 and 40-60 cm of the soil depth was 13. 47 and 9. 09 mg/kg,respectively,which was 46. 9% and 64. 2% lower than that at 0-20 cm( 25. 36 mg/kg) of the soil depth. The soil nitrate nitrogen content of 20 years of forest age was 19. 24 mg/kg,which was25. 8% lower than that of 10 years of forest age,showing significant difference( P < 0. 05). In addition,with the increase of the age of L. principis-rupprechtii,soil catalase( CAT),alkaline phosphatase( ALP) and urease( Ure) decreased,and the decline of ALP was slow,while CAT and Ure decreased significantly. In summary,it is concluded that the soil fertility of forest land declined with the increase of forest age on the basis of change trend of soil nutrient and soil enzyme activity in the surveyed forest age.
基金funding from National Natural Science Foundation of China(No.31870387),China Scholarship Council.
文摘Background:Stem CO_(2) efflux(E_(S))plays a critical role in the carbon budget of forest ecosystems.Thinning is a core practice for sustainable management of plantations.It is therefore necessary and urgent to study the effect and mechanism of thinning intensity(TI)on E_(S).Methods:In this study,five TIs were applied in Larix principis-rupprechtii Mayr 21-,25-,and 41-year-old stands in North China in 2010.Portable infrared gas analyzer(Li-8100 A)was used to measure ES and its association with environmental factors at monthly intervals from May to October in 2013 to 2015.In addition,nutrients,wood structure and nonstructural carbon(NSC)data were measured in August 2016.Results:The results show that ES increased with increasing TI.The maximum ES values occurred at a TI of 35%(3.29,4.57 and 2.98μmol·m^(-2)·s^(-1))and were 1.54-,1.94-and 2.89-fold greater than the minimum E_(S) value in the CK stands(2.14,2.35 and 1.03μmol·m^(-2)·s^(-1))in July for the 21-,25-and 41-year-old forests,respectively.The E_(S) of the trees in low-density stands was more sensitive to temperature than that of the trees in high-density stands.Soluble sugars(SS)and temperature are the main factors affecting ES.When the stand density is low enough as 41-year-old L.principis-rupprechtii forests with TI 35%,bark thickness(BT)and humidity should be considered in addition to air temperature(T_(a)),wood temperature(T_(w)),sapwood width(SW),nitrogen concentration(N)and SS in the evaluation of ES.If a change in stand density is ignored,the CO_(2) released from individual 21-,25-and 41-year-old trees could be underestimated by 168.89%,101.94% and 200.49%,respectively.CO_(2) release was estimated based on the stem equation in combination with the factors influencing ES for reference.Conclusions:We suggest that it is not sufficient to conventional models which quantify ES only by temperature and that incorporating the associated drivers(e.g.density,SS,SW and N)based on stand density into conventional models can improve the accuracy of ES estimates.
基金the Natural Science Foundation of Shanxi Province,China(2010011041-1)the National Natural Science Foundation of China(41271531).
文摘Prince Rupprecht’s larch(Larix principis-rupprechtii Mayr.),a deciduous conifer,widely grows in middle and high elevations of Northern China.Its natural distribution has sharply decreased and has become fragmented,which may have resulted in the loss of genetic variation.In this study,ten natural populations across the entire range of this species were analyzed using amplifi ed fragment length polymorphism markers.A total of 309 loci were detected from 225 individuals of these populations,of which 261(84.5%)were polymorphic.At the species level,the genetic diversity was high(average of the Nei’s genetic diversity H e=0.2602,and Shannon’s information index I=0.3967).The results of molecular variance analysis showed that 90.71%of the genetic diversity occurred within populations.The genetic diff erentiation among populations was moderate as a whole(F ST=0.0929,G ST=0.1510),which is consistent with the moderate level of gene fl ow among populations(N m=2.8116).Based on the unweighted pair group method with arithmetic mean and STRU CTU RE analysis,these populations were grouped into three genetically distinct clusters.The degree of inter-population diff erentiation(G ST=0.1338)for the south group was larger than that for the north group(G ST=0.0915).There was a signifi cant correlation between genetic distance and geographic distance across the species range(r=0.316,P<0.05).Genetic diversity was signifi-cantly associated with longitude but not elevation or climatic factors.The populations with high genetic diversity from each cluster are therefore recommended for future conservation and management of this species.
基金supported by the National S&T Support Projects for the 11th Five-Year Plan (2006BA-D01A14)the National High-Tech "863" Program of China (2006AA100109)the National "973" Program (2009CB119107)
文摘SSH was used to analyze gene transactivation during root formation of Larix cuttings. Two subtractive cDNA libraries were constructed from clone 31-6 as tester or driver and clone 15-4 as driver or tester. The SSH PCR products from the libraries were cloned into a pGEM-T easy vector and after PCR and dot blot analysis, positive clones were selected, sequenced and compared to the database in GenBank with BLASTX. The results of a sequence assembly in two libraries show that 521 UniEST (expressed sequence tag) were obtained. These 521 UniEST belong to metabolism, signal pathways, transport, resistance, developmental processes, local- ization, unknown proteins and "no hits found". All of these suggest that subtractive cDNA libraries during root formation of Larix cuttings were constructed successfully.
基金the National Natural Science Foundation of China(Nos.42161144008U21A2005+3 种基金U20A2085)the National Key Research and Development Program of China(2022YFF08018042022YFF08018032022YFF1300404)。
文摘Extreme climate has increasingly led to negative impacts on forest ecosystems globally,especially in semiarid areas where forest ecosystems are more vulnerable.However,it is poorly understood how tree growth is affected by different drought events.In 2006–2009,the larch plantations in the semiarid areas of Northwest China were negatively affected by four consecutive dry years,which was a very rare phenomenon that may occur frequently under future climate warming.In this study,we analyzed the effect of these consecutive dry years on tree growth based on the data of the tree rings in the dominant layer of the forest canopy on a larch plantation.We found that the tree-ring width index(RWI)in dry years was lower than that in normal years,and it experienced a rapidly decreasing trend from 2006 to 2009(slope=-0.139 year^(-1),r=-0.94)due to water supply deficits in those dry years.Drought induced legacy effects of tree growth reduction,and consecutive dry years corresponded with greater growth reductions and legacy effects.Growth reductions and legacy effects were significantly stronger in the third and fourth consecutive dry years than that of single dry year(p<0.05),which might have been due to the cumulative stress caused by consecutive dry years.Our results showed that larch trees experienced greater tree growth reduction due to consecutive dry years and their legacy effect,and the trees had lower recovery rates after consecutive dry years.Our results highlight that consecutive dry years pose a new threat to plantations under climate warming,and thus,the effect of climate extremes on tree growth should be considered in growth models in semiarid areas.
文摘Horizontal and veftical distributions of fine root abundance (mass per unit ground surface arca) were investi-gated in a densely planted larch - ash -stripe - mixed tbrest on dark broxvn forest soil in northeast China. There was evidencefor some degree of below-ground niche partitioning (or differentiation) betmpen the two species in hoth the horizontal andvertical directions. The ash fine roots largely penetrated into the larch belt (larch Sub-community) in surttrce soil (0-20 cm),indicating a possible inductive effect of larch ecological field on ash roots, while the penetration of larch tine roots into ashbelt (ash sub-community) was much restricted- which reflected a negative influence of ash ccological tield on Iarch roots. Inthe vertical direction of marginal soil the ash tine roots were mainly distributed in topsoil with a vertical gradient similar tothat as in the internal ash sub-community. but the larch fine roots were relatively compelled to deepcr soil layers by the com-petition (or exclusion) of marginal ash trees. All the dit1brences or complemcntarity wcre considered to the result of inter-specitic competition, which was important to the coexistence of the two tbrest species and the sustainability of mixed planta-tion.
基金supported by the grants of the National Natural Science Foundation of China (No. 31100470)the Ministry of Science and Technology of China (No. 2011BAD37B02-2)
文摘Fine root turnover plays a key role in carbon (C) budgets and nutrients cycles in forest ecosystems. However, the difference between branch-order-based and diameter-based approaches in estimating fine root turnover is still unclear. We studied root biomass turnover based on multiplying root standing biomass by turnover rate (inverse of median root longevity) in two Chinese temperate tree species, Fraxinus mand- shurica Rupr. and Larix gmelinii Rupr. The minirhizotron (MR) tech- nique was used to estimate longevities for first and second order roots, and total roots (R,o,al) apparent on the MR tube surface. The correspond- ing biomass for each root group was estimated by soil monolith. The difference in biomass turnover between Rtotal and the sum of the first and second order roots was used to represent the discrepancy between di- ameter- and order-based approaches. First order roots had shorter life spans and higher biomass turnover rates than the second order roots in both species. Biomass turnover estimated by the order-based method for F. mandshurica and L. gmelinii were 155.4 g.m2.aland 158.9 g.m2.a-1, respectively, in comparison with 99.5 g.m^-2-a^-1 and 117.7 g.m^-2.a^-1 estimated by the diameter-based method, indicating that the diameter-based approach underestimated biomass turnover. The most probable reason was that the order-based method enhanced separation of the heterogeneous root population into relatively homogenous root groups with varying turnover rates. We conclude that separating fine root pool into different branch orders can improve the accuracy of estimates for fine root turnover, as well as the understanding of the belowground C allocation and nutrient cycling at ecosystem level.