The resorption of nutrients by plants before litter fall and the mineralization of nutrients from plant litter by soil processes are both important pathways supporting primary productivity. While the positive relation...The resorption of nutrients by plants before litter fall and the mineralization of nutrients from plant litter by soil processes are both important pathways supporting primary productivity. While the positive relationship between plant biodiversity and primary productivity is widely accepted for natural ecosystems, the roles of nutrient resorption and mineralization in mediating that relationship remains largely unknown. Here, we quantified the relative importance of nitrogen(N) resorption and N mineralization in driving plant community N investment and the correlation between species diversity and community productivity along an N-limited successional chronosequence of the mixed broadleaved–Korean pine(Pinus koraiensis) forest in northeastern China. Leaf N resorption efficiency(NRE) at the community level increased significantly along the successional chronosequence,whereas litter N mineralization rate decreased significantly. Leaf NRE was more important than litter N mineralization rate in driving the diversity–productivity relationship. However, higher leaf NRE led to less N mineralization as succession progressed along the chronosequence. Our results highlight the importance of the N resorption pathway rather than the N mineralization pathway for forest N acquisition with community succession,and they provide mechanistic insights into the positive effects of biodiversity on ecosystem functioning. In future forest management practices, we recommend appropriate application of N fertilizer to mitigate the adverse effects of N-poor soil on seedling regeneration during late succession and thus maintain the sustainable development of temperate forest ecosystems.展开更多
Convenient and effective methods to determine seasonal changes in individual leaf area(LA) and leaf mass(LM) of plants are useful in research on plant physiology and forest ecology.However,practical methods for estima...Convenient and effective methods to determine seasonal changes in individual leaf area(LA) and leaf mass(LM) of plants are useful in research on plant physiology and forest ecology.However,practical methods for estimating LA and LM of elm(Ulmus japonica) leaves in different periods have rarely been reported.We collected sample elm leaves in June,July and September.Then,we developed allometric models relating LA,LM and leaf parameters,such as leaf length(L) and width(W) or the product of L and W(LW).Our objective was to find optimal allometric models for conveniently and effectively estimating LA and LM of elm leaves in different periods.LA and LM were significantly correlated with leaf parameters(P<0.05),and allometric models with LW as an independent variable were best for estimating LA and LM in each period.A linear model was separately developed to predict LA of elm leaves in June,July and September,and it yielded high accuracies of 93,96 and 96%,respectively.Similarly,a specific allometric model for predicting LM was developed separately in three periods,and the optimal model form in both June and July was a power model,but the linear model was optimal for September.The accuracies of the allometric models in predicting LM were 88,83 and 84% for June,July and September,respectively.The error caused by ignoring seasonal variation of allometric models in predicting LA and LM in the three periods were 1–4 and 16–59%,respectively.展开更多
Elevated atmospheric nitrogen(N) deposition has been detected in many regions of China, but its effects on soil N transformation in temperate forest ecosystems are not well known. We therefore simulated N deposition w...Elevated atmospheric nitrogen(N) deposition has been detected in many regions of China, but its effects on soil N transformation in temperate forest ecosystems are not well known. We therefore simulated N deposition with four levels of N addition rate(N0, N30, N60, and N120) for6 years in an old-growth temperate forest in Xiaoxing'an Mountains in Northeastern China. We measured gross N transformation rates in the laboratory using ^(15)N tracing technology to explore the effects of N deposition on soil gross N transformations taking advantage of N deposition soils. No significant differences in gross soil N transformation rates were observed after 6 years of N deposition with various levels of N addition rate. For all N deposition soils, the gross NH_4^+ immobilization rates were consistently lower than the gross N mineralization rates,leading to net N mineralization. Nitrate(NO_3^-) was primarily produced via oxidation of NH_4^+(i.e., autotrophic nitrification), whereas oxidation of organic N(i.e., heterotrophic nitrification) was negligible. Differences between the quantity of ammonia-oxidizing bacteria and ammonia-oxidizing archaea were not significant for any treatment, which likely explains the lack of a significant effect on gross nitrification rates. Gross nitrification rates were much higher than the total NO_3^- consumption rates,resulting in a build-up of NO_3^-, which highlights the high risk of N losses via NO_3^- leaching or gaseous N emissions from soils. This response is opposite that of typical N-limited temperate forests suffering from N deposition,suggesting that the investigated old-growth temperate forest ecosystem is likely to approach N saturation.展开更多
The purpose of this study was to classify current forest cover types,and to investigate stand development patterns for natural forests in six areas in northern Baekdudaegan,South Korea.Twenty-eight independent forest ...The purpose of this study was to classify current forest cover types,and to investigate stand development patterns for natural forests in six areas in northern Baekdudaegan,South Korea.Twenty-eight independent forest communities were aggregated into eight forest cover types by species composition in the overstory of each forest community.The forest cover types were of mixed mesophytic,‘‘others' ' deciduous,Quercus mongolica dominant,Q.mongolica pure,Pinus densiflora–Q.mongolica,P.densiflora,Betula ermanii,and Q.mongolica–P.koraiensis.The ecological information was organized by importance value and species diversity for each forest type.Based on the correlation between species diversity index and the abundance of Q.mongolica plus P.densiflora for corresponding forest cover types,we compared the developmental process and approximate successional pathway between each cover type.The P.densiflora forest cover type changes into the P.densiflora–Q.mongolica cover type,followed by the Q.mongolica dominant cover type through continuous invasion of the oak trees.Furthermore,the Q.mongolica pure cover type would spread toward the Q.mongolica dominant cover type with a mixture of various deciduous tree species.The Q.mongolica dominant cover type progresses through the other deciduous cover types to the mixed mesophytic cover type with diversified composition and structure.On the mid to lower slopes,with loamy soils and good moisture conditions,various deciduous forest types should progress,by ecological succession,toward the mixed mesophytic cover type without any further disturbance.展开更多
Investigating the effects of ontogenetic stage and leaf age on leaf traits is important for understanding the utilization and distribution of resources in the process of plant growth.However,few studies have been cond...Investigating the effects of ontogenetic stage and leaf age on leaf traits is important for understanding the utilization and distribution of resources in the process of plant growth.However,few studies have been conducted to show how traits and trait-trait relationships change across a range of ontogenetic stage and leaf age for evergreen coniferous species.We divided 67 Pinus koraiensis Sieb.et Zucc.of various sizes(0.3-100 cm diameter at breast height,DBH)into four ontogenetic stages,i.e.,young trees,middle-aged trees,mature trees and over-mature trees,and measured the leaf mass per area(LMA),leaf dry matter content(LDMC),and mass-based leaf nitrogen content(N)and phosphorus content(P)of each leaf age group for each sampled tree.One-way analysis of variance(ANOVA)was used to describe the variation in leaf traits by ontogenetic stage and leaf age.The standardized major axis method was used to explore the effects of ontogenetic stage and leaf age on trait-trait relationships.We found that LMA and LDMC increased significantly and N and P decreased significantly with increases in the ontogenetic stage and leaf age.Most trait-trait relationships were consistent with the leaf economic spectrum(LES)at a global scale.Among them,leaf N content and LDMC showed a significant negative correlation,leaf N and P contents showed a significant positive correlation,and the absolute value of the slopes of the trait-trait relationships showed a gradually increasing trend with an increasing ontogenetic stage.LMA and LDMC showed a significant positive correlation,and the slopes of the trait-trait relationships showed a gradually decreasing trend with leaf age.Additionally,there were no significant relationships between leaf N content and LMA in most groups,which is contrary to the expectation of the LES.Overall,in the early ontogenetic stages and leaf ages,the leaf traits tend to be related to a"low investment-quick returns"resource strategy.In contrast,in the late ontogenetic stages and leaf ages,they tend to be related to a"high investment-slow returns"resource strategy.Our results reflect the optimal allocation of resources in Pinus koraiensis according to its functional needs during tree and leaf ontogeny.展开更多
Thinning is an important forest management practice that has great potential to influence regional soil carbon storage and dynamics.The present study measured soil respiration(RS,the efflux of CO2 emitted)and its two ...Thinning is an important forest management practice that has great potential to influence regional soil carbon storage and dynamics.The present study measured soil respiration(RS,the efflux of CO2 emitted)and its two components(heterotrophic(RH)and autotrophic(RA)respiration)from soil 42 years after thinning in comparison to un-thinning(control).Autotrophic respiration was significantly greater in the thinning plot,approximately 44%higher compared to the control,while both RSand RHwere slightly,but not significantly,higher in the thinning plot.Higher fine root biomass might have contributed to the higher RAin the thinning plot.Both RSand RHshowed clear soil temperature-dependent seasonal patterns,whereas RAwas less responsive to changes in temperature,especially within one specific season.The annual and season-specific temperature sensitivities of RSand RHwere lower in the thinning plot,specifically during the mid-growing season.Furthermore,variations in the season-specific temperature sensitivity of RSand RHwere less intense in the thinning plot.We conclude that forest thinning can reduce the temperature sensitivity of RSand RHduring the mid-growing season and increase soil CO2 emission in the long term.展开更多
Disentangling the relative roles of environmental and spatial processes in community assembly is a major task of community ecology.It is necessary to uncover this question at multiple spatial scales;however,the relati...Disentangling the relative roles of environmental and spatial processes in community assembly is a major task of community ecology.It is necessary to uncover this question at multiple spatial scales;however,the relative importance of spatial and environmental processes on ground-dwelling beetle assembly at a small scale is still unclear.Based on two permanent plots(each 300 m)located in primary mixed broadleaved-Korean pine forests,the topographic,soil,and plant factors were collected,and the spatial variables(MEMs,distancebased Moran’s eigenvector maps)were calculated.A redundancy analysis(RDA)was used to evaluate the influence of topographic,soil,and plant variables on ground-dwelling beetle compositions.A variation partitioning analysis was used to quantify the relative contributions of environmental and spatial processes on the assembly of ground-dwelling beetles.The results of the RDA reported that the soil,plant,and topographic variables affected Staphylinidae and Silphidae beetle compositions in both plots.According to the results of variation partitioning,pure soil and plant variables were important for the assembly of Silphidae beetles in the LS plot.The contributions of pure topographic,soil,and plant variables were significantly lower than those of pure spatial variables.The contributions of pure spatial variables were significant for the assembly of Staphylinidae and Silphidae beetles in both plots.In addition,the relative importance of environmental and spatial processes was not significantly changed after including more environmental variables and the unexplained variations.Finally,this study suggests that both spatial and environmental variables are important for the assembly of ground-dwelling beetle communities,while pure spatial variables are more important than pure environmental variables at a small scale(300 m).展开更多
基金financially supported by the National Natural Science Foundation of China(No.32071533)the Fundamental Research Funds for the Central Universities,China(2572020AW13)。
文摘The resorption of nutrients by plants before litter fall and the mineralization of nutrients from plant litter by soil processes are both important pathways supporting primary productivity. While the positive relationship between plant biodiversity and primary productivity is widely accepted for natural ecosystems, the roles of nutrient resorption and mineralization in mediating that relationship remains largely unknown. Here, we quantified the relative importance of nitrogen(N) resorption and N mineralization in driving plant community N investment and the correlation between species diversity and community productivity along an N-limited successional chronosequence of the mixed broadleaved–Korean pine(Pinus koraiensis) forest in northeastern China. Leaf N resorption efficiency(NRE) at the community level increased significantly along the successional chronosequence,whereas litter N mineralization rate decreased significantly. Leaf NRE was more important than litter N mineralization rate in driving the diversity–productivity relationship. However, higher leaf NRE led to less N mineralization as succession progressed along the chronosequence. Our results highlight the importance of the N resorption pathway rather than the N mineralization pathway for forest N acquisition with community succession,and they provide mechanistic insights into the positive effects of biodiversity on ecosystem functioning. In future forest management practices, we recommend appropriate application of N fertilizer to mitigate the adverse effects of N-poor soil on seedling regeneration during late succession and thus maintain the sustainable development of temperate forest ecosystems.
基金financially supported by the National Natural Science Foundation of China(No.31600587)
文摘Convenient and effective methods to determine seasonal changes in individual leaf area(LA) and leaf mass(LM) of plants are useful in research on plant physiology and forest ecology.However,practical methods for estimating LA and LM of elm(Ulmus japonica) leaves in different periods have rarely been reported.We collected sample elm leaves in June,July and September.Then,we developed allometric models relating LA,LM and leaf parameters,such as leaf length(L) and width(W) or the product of L and W(LW).Our objective was to find optimal allometric models for conveniently and effectively estimating LA and LM of elm leaves in different periods.LA and LM were significantly correlated with leaf parameters(P<0.05),and allometric models with LW as an independent variable were best for estimating LA and LM in each period.A linear model was separately developed to predict LA of elm leaves in June,July and September,and it yielded high accuracies of 93,96 and 96%,respectively.Similarly,a specific allometric model for predicting LM was developed separately in three periods,and the optimal model form in both June and July was a power model,but the linear model was optimal for September.The accuracies of the allometric models in predicting LM were 88,83 and 84% for June,July and September,respectively.The error caused by ignoring seasonal variation of allometric models in predicting LA and LM in the three periods were 1–4 and 16–59%,respectively.
基金supported by Grants from the ‘‘973’’ Project(2014CB953803)the Fundamental Research Funds for the Central Universities(2572017EA02)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD,164320H116)
文摘Elevated atmospheric nitrogen(N) deposition has been detected in many regions of China, but its effects on soil N transformation in temperate forest ecosystems are not well known. We therefore simulated N deposition with four levels of N addition rate(N0, N30, N60, and N120) for6 years in an old-growth temperate forest in Xiaoxing'an Mountains in Northeastern China. We measured gross N transformation rates in the laboratory using ^(15)N tracing technology to explore the effects of N deposition on soil gross N transformations taking advantage of N deposition soils. No significant differences in gross soil N transformation rates were observed after 6 years of N deposition with various levels of N addition rate. For all N deposition soils, the gross NH_4^+ immobilization rates were consistently lower than the gross N mineralization rates,leading to net N mineralization. Nitrate(NO_3^-) was primarily produced via oxidation of NH_4^+(i.e., autotrophic nitrification), whereas oxidation of organic N(i.e., heterotrophic nitrification) was negligible. Differences between the quantity of ammonia-oxidizing bacteria and ammonia-oxidizing archaea were not significant for any treatment, which likely explains the lack of a significant effect on gross nitrification rates. Gross nitrification rates were much higher than the total NO_3^- consumption rates,resulting in a build-up of NO_3^-, which highlights the high risk of N losses via NO_3^- leaching or gaseous N emissions from soils. This response is opposite that of typical N-limited temperate forests suffering from N deposition,suggesting that the investigated old-growth temperate forest ecosystem is likely to approach N saturation.
基金support of ‘Forest Science&Technology Projects(Project No.S211012L030110)’ provided by Korea Forest Service
文摘The purpose of this study was to classify current forest cover types,and to investigate stand development patterns for natural forests in six areas in northern Baekdudaegan,South Korea.Twenty-eight independent forest communities were aggregated into eight forest cover types by species composition in the overstory of each forest community.The forest cover types were of mixed mesophytic,‘‘others' ' deciduous,Quercus mongolica dominant,Q.mongolica pure,Pinus densiflora–Q.mongolica,P.densiflora,Betula ermanii,and Q.mongolica–P.koraiensis.The ecological information was organized by importance value and species diversity for each forest type.Based on the correlation between species diversity index and the abundance of Q.mongolica plus P.densiflora for corresponding forest cover types,we compared the developmental process and approximate successional pathway between each cover type.The P.densiflora forest cover type changes into the P.densiflora–Q.mongolica cover type,followed by the Q.mongolica dominant cover type through continuous invasion of the oak trees.Furthermore,the Q.mongolica pure cover type would spread toward the Q.mongolica dominant cover type with a mixture of various deciduous tree species.The Q.mongolica dominant cover type progresses through the other deciduous cover types to the mixed mesophytic cover type with diversified composition and structure.On the mid to lower slopes,with loamy soils and good moisture conditions,various deciduous forest types should progress,by ecological succession,toward the mixed mesophytic cover type without any further disturbance.
基金The work was financially supported by the National Natural Science Foundation of China(No.31971636)Yong Elite Scientists Sponsorship Program by CAST(2018QNRC001)the Fundamental Research Fund for the Central Universities(2572018CG03).
文摘Investigating the effects of ontogenetic stage and leaf age on leaf traits is important for understanding the utilization and distribution of resources in the process of plant growth.However,few studies have been conducted to show how traits and trait-trait relationships change across a range of ontogenetic stage and leaf age for evergreen coniferous species.We divided 67 Pinus koraiensis Sieb.et Zucc.of various sizes(0.3-100 cm diameter at breast height,DBH)into four ontogenetic stages,i.e.,young trees,middle-aged trees,mature trees and over-mature trees,and measured the leaf mass per area(LMA),leaf dry matter content(LDMC),and mass-based leaf nitrogen content(N)and phosphorus content(P)of each leaf age group for each sampled tree.One-way analysis of variance(ANOVA)was used to describe the variation in leaf traits by ontogenetic stage and leaf age.The standardized major axis method was used to explore the effects of ontogenetic stage and leaf age on trait-trait relationships.We found that LMA and LDMC increased significantly and N and P decreased significantly with increases in the ontogenetic stage and leaf age.Most trait-trait relationships were consistent with the leaf economic spectrum(LES)at a global scale.Among them,leaf N content and LDMC showed a significant negative correlation,leaf N and P contents showed a significant positive correlation,and the absolute value of the slopes of the trait-trait relationships showed a gradually increasing trend with an increasing ontogenetic stage.LMA and LDMC showed a significant positive correlation,and the slopes of the trait-trait relationships showed a gradually decreasing trend with leaf age.Additionally,there were no significant relationships between leaf N content and LMA in most groups,which is contrary to the expectation of the LES.Overall,in the early ontogenetic stages and leaf ages,the leaf traits tend to be related to a"low investment-quick returns"resource strategy.In contrast,in the late ontogenetic stages and leaf ages,they tend to be related to a"high investment-slow returns"resource strategy.Our results reflect the optimal allocation of resources in Pinus koraiensis according to its functional needs during tree and leaf ontogeny.
基金financially supported by the National Natural Science Foundation of China(No.31730015)the Fundamental Research Funds for the Central Universities,China(No.2572017EA02)。
文摘Thinning is an important forest management practice that has great potential to influence regional soil carbon storage and dynamics.The present study measured soil respiration(RS,the efflux of CO2 emitted)and its two components(heterotrophic(RH)and autotrophic(RA)respiration)from soil 42 years after thinning in comparison to un-thinning(control).Autotrophic respiration was significantly greater in the thinning plot,approximately 44%higher compared to the control,while both RSand RHwere slightly,but not significantly,higher in the thinning plot.Higher fine root biomass might have contributed to the higher RAin the thinning plot.Both RSand RHshowed clear soil temperature-dependent seasonal patterns,whereas RAwas less responsive to changes in temperature,especially within one specific season.The annual and season-specific temperature sensitivities of RSand RHwere lower in the thinning plot,specifically during the mid-growing season.Furthermore,variations in the season-specific temperature sensitivity of RSand RHwere less intense in the thinning plot.We conclude that forest thinning can reduce the temperature sensitivity of RSand RHduring the mid-growing season and increase soil CO2 emission in the long term.
基金supported by the National Natural Sciences Foundations of China(grant nos.41871042,41471037,41430857,and 41501263)by the Excellent Youth Scholars of Harbin Normal University(grant no.XKYQ201401)by the Program of Introducing Talents of Discipline to Universities(grant no.B16011).
文摘Disentangling the relative roles of environmental and spatial processes in community assembly is a major task of community ecology.It is necessary to uncover this question at multiple spatial scales;however,the relative importance of spatial and environmental processes on ground-dwelling beetle assembly at a small scale is still unclear.Based on two permanent plots(each 300 m)located in primary mixed broadleaved-Korean pine forests,the topographic,soil,and plant factors were collected,and the spatial variables(MEMs,distancebased Moran’s eigenvector maps)were calculated.A redundancy analysis(RDA)was used to evaluate the influence of topographic,soil,and plant variables on ground-dwelling beetle compositions.A variation partitioning analysis was used to quantify the relative contributions of environmental and spatial processes on the assembly of ground-dwelling beetles.The results of the RDA reported that the soil,plant,and topographic variables affected Staphylinidae and Silphidae beetle compositions in both plots.According to the results of variation partitioning,pure soil and plant variables were important for the assembly of Silphidae beetles in the LS plot.The contributions of pure topographic,soil,and plant variables were significantly lower than those of pure spatial variables.The contributions of pure spatial variables were significant for the assembly of Staphylinidae and Silphidae beetles in both plots.In addition,the relative importance of environmental and spatial processes was not significantly changed after including more environmental variables and the unexplained variations.Finally,this study suggests that both spatial and environmental variables are important for the assembly of ground-dwelling beetle communities,while pure spatial variables are more important than pure environmental variables at a small scale(300 m).
基金the National Natural Science Foundation of China(31870399,32071533)the Strategic Priority Research Program ofthe(Chinese Academy of Sciences(XDB31030000).
基金This study was financially supported by the NationalNatural Science Foundation of China(31870399,32071533)the Strategic Priority ResearchProgram of the Chinese Academy of Sciences(XDB31030000).
