China's forests cover 208.3 million ha and span a wide range of climates and a large variety of forest types, including tropical, temperate, and boreal forests. However, the variation patterns of fine root (< 2...China's forests cover 208.3 million ha and span a wide range of climates and a large variety of forest types, including tropical, temperate, and boreal forests. However, the variation patterns of fine root (< 2 mm in diameter) biomass, production, and turnover from the south to the north are unclear. This study summarizes fine root biomass (FRB), production (FRP) and turnover rate (FRT) in China's forests as reported by 140 case studies published from 1983 to 2014. The results showed that the mean values of FRB, FRP and FRT in China's forests were 278 g m(-2), 366 g m(-2) a(-1), and 1.19 a(-1), respectively. Compared with other studies at the regional or global scales, FRB in China's forests was lower, FRP was similar to estimates at the global scale, but FRT was much higher. FRB, FRP, and FRT in China's forests increased with increasing mean annual precipitation (MAP), indicating that fine root variables were likely related to MAP, rather than mean annual temperature or latitude. This is possibly due to the small variation in temperature but greater variation in precipitation during the growing season. These findings suggest that spatiotemporal variation in precipitation has a more profound impact on fine root dynamics in China's forests, and this will impact carbon and nutrient cycles driven by root turnover in the future.展开更多
Increasing evidence suggests that fine roots are particularly sensitive to environmental changes,making them essential in responding and adapting forest ecosystems to climate change.However,we still lack a fundamental...Increasing evidence suggests that fine roots are particularly sensitive to environmental changes,making them essential in responding and adapting forest ecosystems to climate change.However,we still lack a fundamental understanding of the underlying mechanisms that control fine root plasticity.The objective of this study was to determine the influence of soil moisture changes on fine root dynamics and morphology of European beech(Fagus sylvatica L.).We conducted a 30-month study of fine root traits,i.e.,fine root biomass(FRB),productivity,mortality,turnover,specific root length(SRL),specific root area(SRA),and root tip frequency(RTF),along a soil moisture gradient from dry,intermediate,and wet conditions in a near-natural mature beech forest.Sequential root coring with accompanying soil measurements was carried out at three study sites reflecting the gradient in soil water availability.For most fine root traits,we found significant differences between the upper 10 cm and lower soil depths.FRB showed significant differences between study sites,with the lowest FRB at the dry site.However,productivity,turnover,SRL,SRA,and RTF showed no significant differences between sites,but a high variability between seasons,suggesting an adaptation to short-term fluctuations but not to long-term gradients in soil water content(SWC).Linear mixed models revealed that decreasing SWC led to a significant increase in SRL,SRA,and RTF(standardized coefficients:-1.0±0.46,-1.1±0.46,and-1.1±0.43,respectively).Our observations indicate an adaptation strategy of beech to low availability of soil water and drought by forming thin absorptive roots and by maintaining a high seasonal plasticity to tolerate fluctuations in soil moisture.By highlighting the belowground morphological adaptations of mature forests to low soil water availability,our results provide novel insights into the structure and dynamics of forest ecosystem adaptations to climate change.展开更多
Fine roots play key roles in belowground C cycling in terrestrial ecosystems.Based on their distinct functions,fi ne roots are either absorptive fi ne roots(AFRs)or transport fi ne roots(TFRs).However,the function-bas...Fine roots play key roles in belowground C cycling in terrestrial ecosystems.Based on their distinct functions,fi ne roots are either absorptive fi ne roots(AFRs)or transport fi ne roots(TFRs).However,the function-based fi ne root dynamics of trees and their responses to forest stand properties remain unclear.Here,we studied the dynamics of AFRs and TFRs and their responses to stand conditions and root density in a subtropical montane mixed forest based on a 2-a root window experiment.Mean(±SE)annual production,mortality,and turnover rate of AFRs were 7.87±0.17 m m^(−2)a^(−1),8.13±0.20 m m^(−2)a^(−1)and 2.96±0.24 a^(−1),respectively,compared with 7.09±0.17 m m^(−2)a^(−1),4.59±0.17 m m^(−2)a^(−1),and 2.01±0.22 a^(−1),respectively,for TFRs.The production and mortality of fi ne roots were signifi cantly higher in high root-density sites than in low-root density sites,whereas the turnover of fi ne roots was faster in the low root-density sites.Furthermore,root density had a larger positive eff ect than other environmental factors on TFR production but had no obvious impact on AFR production.Tree species diversity had an apparent positive eff ect on AFR production and was the crucial driver of AFR production,probably due to a complementary eff ect,but had no evident impact on TFR.Both tree density and tree species diversity were positively correlated with the mortality of AFRs and negatively related to the turnover of TFRs,suggesting that higher root density caused stronger competition for rooting space and that plants tend to reduce maintenance costs by decreasing TFR turnover.These fi ndings illustrated the importance of root functional groups in understanding root dynamics and their responses to changes in environmental conditions.展开更多
Plant roots dynamics responses to elevated atmospheric CO2 concentration, increased temperature and changed precipitation can be a key link between plant growth and long-term changes in soil organic matter and ecosyst...Plant roots dynamics responses to elevated atmospheric CO2 concentration, increased temperature and changed precipitation can be a key link between plant growth and long-term changes in soil organic matter and ecosystem carbon balance. This paper reviews some experiments and hypotheses developed in this area, which mainly include plant fine roots growth, root turnover, root respiration and other root dynamics responses to elevated CO2 and global climate change. Some recent new methods of studying root systems were also discussed and summarized. It holds herein that the assemblage of information about root turnover patterns, root respiration and other dynamic responses to elevated atmospheric CO2 and global climatic change can help to better understand and explore some new research areas. In this paper, some research challenges in the plant root responses to the elevated CO2 and other environmental factors during global climate change were also demonstrated.展开更多
Fine root dynamics are crucial for terrestrial ecosystem productivity and nutrient cycling.However,the effects of nitrogen(N)deposition on fine root dynamics in temperate ecosystems remain poorly understood.In this st...Fine root dynamics are crucial for terrestrial ecosystem productivity and nutrient cycling.However,the effects of nitrogen(N)deposition on fine root dynamics in temperate ecosystems remain poorly understood.In this study,we used a meta-analysis to explore the general patterns and key drivers of fine root biomass and turnover in temperate forests and grasslands in response to N application.We found that N application significantly reduced fine root biomass compared to the control group(no N application),with notable differences across N forms.However,the impact of N application on fine root biomass remained consistent across ecosystem types,soil depths and root diameters.In terms of fine root turnover rate,N application had no significant overall effect,and the response did not vary across N forms,ecosystem types,soil depths or root diameters.However,significant differences were observed across methods for estimating fine root turnover rate.Multiple regression analysis showed that mean annual temperature(MAT)and experimental factors(including duration and N application rates)were the primary determinants of fine root biomass response to N application.In contrast,fine root turnover was not significantly influenced by any of the factors analyzed.Overall,our findings highlight the negative impact of N application on fine root biomass and the neutral effect on fine root turnover,and also suggest that find root dynamics are closely associated with experimental factors,including experiment duration and N application rate.This study provides an important advancement in understanding the feedback between root dynamics and global change,offering insights for developing management strategies to address belowground ecological processes under global change scenarios.展开更多
Fine root turnover is a major pathway for carbon and nutrient cycling in forest ecosystems.However,to estimate fine root turnover,it is important to first understand the fine root dynamic processes associated with soi...Fine root turnover is a major pathway for carbon and nutrient cycling in forest ecosystems.However,to estimate fine root turnover,it is important to first understand the fine root dynamic processes associated with soil resource availability and climate factors.The objectives of this study were:(1)to examine patterns of fine root production and mortality in different seasons and soil depths in the Larix gmelinii and Fraxinus mandshurica plantations,(2)to analyze the correlation of fine root production and mortality with environmental factors such as air temperature,precipitation,soil temperature and available nitrogen,and(3)to estimate fine root turnover.We installed 36 Minirhizotron tubes in six monospecific plots of each species in September 2003 in the Mao’ershan Experimental Forest Station.Minirhizotron sampling was conducted every two weeks from April 2004 to April 2005.We calculated the average fine root length,annual fine root length production and mortality using image data of Minirhizotrons,and estimated fine root turnover using three approaches.Results show that the average growth rate and mortality rate in L.melinii were markedly smaller than in F.mandshurica,and were highest in the surface soil and lowest at the bottom among all the four soil layers.The annual fine root production and mortality in F.mandshurica were significantly higher than in L.gmelinii.The fine root production in spring and summer accounted for 41.7% and 39.7% of the total annual production in F.mandshurica and 24.0% and 51.2% in L.gmelinii.The majority of fine root mortality occurred in spring and summer for F.mandshurica and in summer and autumn for L.gmelinii.The turnover rate was 3.1 a^(-1) for L.gmelinii and 2.7 a^(-1) for F.mandshurica.Multiple regression analysis indicates that climate and soil resource factors together could explain 80% of the variations of the fine root seasonal growth and 95%of the seasonal mortality.In conclusion,fine root production and mortality in L.gmelinii and F.mandshurica have different patterns in different seasons and at different soil depths.Air temperature,precipitation,soil temperature and soil available nitrogen integratively control the dynamics of fine root production,mortality and turnover in both species.展开更多
基金supported by Grants from the National Key Research and Development Program of China(2016YFD06004040604)the Natural Science Foundation of Heilongjiang Province(No.C2016004)
文摘China's forests cover 208.3 million ha and span a wide range of climates and a large variety of forest types, including tropical, temperate, and boreal forests. However, the variation patterns of fine root (< 2 mm in diameter) biomass, production, and turnover from the south to the north are unclear. This study summarizes fine root biomass (FRB), production (FRP) and turnover rate (FRT) in China's forests as reported by 140 case studies published from 1983 to 2014. The results showed that the mean values of FRB, FRP and FRT in China's forests were 278 g m(-2), 366 g m(-2) a(-1), and 1.19 a(-1), respectively. Compared with other studies at the regional or global scales, FRB in China's forests was lower, FRP was similar to estimates at the global scale, but FRT was much higher. FRB, FRP, and FRT in China's forests increased with increasing mean annual precipitation (MAP), indicating that fine root variables were likely related to MAP, rather than mean annual temperature or latitude. This is possibly due to the small variation in temperature but greater variation in precipitation during the growing season. These findings suggest that spatiotemporal variation in precipitation has a more profound impact on fine root dynamics in China's forests, and this will impact carbon and nutrient cycles driven by root turnover in the future.
基金supported by the Federal Ministry of Food and Agriculture (BMEL)the Federal Ministry for the Environment,Nature Conservation,Nuclear Safety and Consumer Protection (BMUV) through the Fachagentur Nachwachsende Rohstoffe e. V.(FNR)(grant no. 2218 WK53X4)
文摘Increasing evidence suggests that fine roots are particularly sensitive to environmental changes,making them essential in responding and adapting forest ecosystems to climate change.However,we still lack a fundamental understanding of the underlying mechanisms that control fine root plasticity.The objective of this study was to determine the influence of soil moisture changes on fine root dynamics and morphology of European beech(Fagus sylvatica L.).We conducted a 30-month study of fine root traits,i.e.,fine root biomass(FRB),productivity,mortality,turnover,specific root length(SRL),specific root area(SRA),and root tip frequency(RTF),along a soil moisture gradient from dry,intermediate,and wet conditions in a near-natural mature beech forest.Sequential root coring with accompanying soil measurements was carried out at three study sites reflecting the gradient in soil water availability.For most fine root traits,we found significant differences between the upper 10 cm and lower soil depths.FRB showed significant differences between study sites,with the lowest FRB at the dry site.However,productivity,turnover,SRL,SRA,and RTF showed no significant differences between sites,but a high variability between seasons,suggesting an adaptation to short-term fluctuations but not to long-term gradients in soil water content(SWC).Linear mixed models revealed that decreasing SWC led to a significant increase in SRL,SRA,and RTF(standardized coefficients:-1.0±0.46,-1.1±0.46,and-1.1±0.43,respectively).Our observations indicate an adaptation strategy of beech to low availability of soil water and drought by forming thin absorptive roots and by maintaining a high seasonal plasticity to tolerate fluctuations in soil moisture.By highlighting the belowground morphological adaptations of mature forests to low soil water availability,our results provide novel insights into the structure and dynamics of forest ecosystem adaptations to climate change.
基金supported by the National Natural Science Foundation of China(Grant No.3217159931870465).
文摘Fine roots play key roles in belowground C cycling in terrestrial ecosystems.Based on their distinct functions,fi ne roots are either absorptive fi ne roots(AFRs)or transport fi ne roots(TFRs).However,the function-based fi ne root dynamics of trees and their responses to forest stand properties remain unclear.Here,we studied the dynamics of AFRs and TFRs and their responses to stand conditions and root density in a subtropical montane mixed forest based on a 2-a root window experiment.Mean(±SE)annual production,mortality,and turnover rate of AFRs were 7.87±0.17 m m^(−2)a^(−1),8.13±0.20 m m^(−2)a^(−1)and 2.96±0.24 a^(−1),respectively,compared with 7.09±0.17 m m^(−2)a^(−1),4.59±0.17 m m^(−2)a^(−1),and 2.01±0.22 a^(−1),respectively,for TFRs.The production and mortality of fi ne roots were signifi cantly higher in high root-density sites than in low-root density sites,whereas the turnover of fi ne roots was faster in the low root-density sites.Furthermore,root density had a larger positive eff ect than other environmental factors on TFR production but had no obvious impact on AFR production.Tree species diversity had an apparent positive eff ect on AFR production and was the crucial driver of AFR production,probably due to a complementary eff ect,but had no evident impact on TFR.Both tree density and tree species diversity were positively correlated with the mortality of AFRs and negatively related to the turnover of TFRs,suggesting that higher root density caused stronger competition for rooting space and that plants tend to reduce maintenance costs by decreasing TFR turnover.These fi ndings illustrated the importance of root functional groups in understanding root dynamics and their responses to changes in environmental conditions.
基金This research was supported by the National Natural Science Foundation of China （90502007, 30270230） the Program for New Century Excellent Talents in University, China （NCET-04-0955）the United Scholar＇s Item of Talent Training Program in West China of CAS and the Program for 0utstanding Talents in Northwest A ＆ F University.
文摘Plant roots dynamics responses to elevated atmospheric CO2 concentration, increased temperature and changed precipitation can be a key link between plant growth and long-term changes in soil organic matter and ecosystem carbon balance. This paper reviews some experiments and hypotheses developed in this area, which mainly include plant fine roots growth, root turnover, root respiration and other root dynamics responses to elevated CO2 and global climate change. Some recent new methods of studying root systems were also discussed and summarized. It holds herein that the assemblage of information about root turnover patterns, root respiration and other dynamic responses to elevated atmospheric CO2 and global climatic change can help to better understand and explore some new research areas. In this paper, some research challenges in the plant root responses to the elevated CO2 and other environmental factors during global climate change were also demonstrated.
基金supported by the National Natural Science Foundation of China(32471644&32300391)the Fujian Provincial Financial Forestry Science and Technology Research Project(2023FKJ16)+1 种基金the Talent Startup Program of Zhejiang A&F University Research and Development Fund(2023LFR052&2023LFR091)the National Key Research and Development Program of China(2022YFD210020002).
文摘Fine root dynamics are crucial for terrestrial ecosystem productivity and nutrient cycling.However,the effects of nitrogen(N)deposition on fine root dynamics in temperate ecosystems remain poorly understood.In this study,we used a meta-analysis to explore the general patterns and key drivers of fine root biomass and turnover in temperate forests and grasslands in response to N application.We found that N application significantly reduced fine root biomass compared to the control group(no N application),with notable differences across N forms.However,the impact of N application on fine root biomass remained consistent across ecosystem types,soil depths and root diameters.In terms of fine root turnover rate,N application had no significant overall effect,and the response did not vary across N forms,ecosystem types,soil depths or root diameters.However,significant differences were observed across methods for estimating fine root turnover rate.Multiple regression analysis showed that mean annual temperature(MAT)and experimental factors(including duration and N application rates)were the primary determinants of fine root biomass response to N application.In contrast,fine root turnover was not significantly influenced by any of the factors analyzed.Overall,our findings highlight the negative impact of N application on fine root biomass and the neutral effect on fine root turnover,and also suggest that find root dynamics are closely associated with experimental factors,including experiment duration and N application rate.This study provides an important advancement in understanding the feedback between root dynamics and global change,offering insights for developing management strategies to address belowground ecological processes under global change scenarios.
基金The funding for this research was provided by theNationalNatural Science Foundation of China(Grant No.30130160).
文摘Fine root turnover is a major pathway for carbon and nutrient cycling in forest ecosystems.However,to estimate fine root turnover,it is important to first understand the fine root dynamic processes associated with soil resource availability and climate factors.The objectives of this study were:(1)to examine patterns of fine root production and mortality in different seasons and soil depths in the Larix gmelinii and Fraxinus mandshurica plantations,(2)to analyze the correlation of fine root production and mortality with environmental factors such as air temperature,precipitation,soil temperature and available nitrogen,and(3)to estimate fine root turnover.We installed 36 Minirhizotron tubes in six monospecific plots of each species in September 2003 in the Mao’ershan Experimental Forest Station.Minirhizotron sampling was conducted every two weeks from April 2004 to April 2005.We calculated the average fine root length,annual fine root length production and mortality using image data of Minirhizotrons,and estimated fine root turnover using three approaches.Results show that the average growth rate and mortality rate in L.melinii were markedly smaller than in F.mandshurica,and were highest in the surface soil and lowest at the bottom among all the four soil layers.The annual fine root production and mortality in F.mandshurica were significantly higher than in L.gmelinii.The fine root production in spring and summer accounted for 41.7% and 39.7% of the total annual production in F.mandshurica and 24.0% and 51.2% in L.gmelinii.The majority of fine root mortality occurred in spring and summer for F.mandshurica and in summer and autumn for L.gmelinii.The turnover rate was 3.1 a^(-1) for L.gmelinii and 2.7 a^(-1) for F.mandshurica.Multiple regression analysis indicates that climate and soil resource factors together could explain 80% of the variations of the fine root seasonal growth and 95%of the seasonal mortality.In conclusion,fine root production and mortality in L.gmelinii and F.mandshurica have different patterns in different seasons and at different soil depths.Air temperature,precipitation,soil temperature and soil available nitrogen integratively control the dynamics of fine root production,mortality and turnover in both species.
