Understanding water uptake depth and its relationship with functional traits offers valuable insights into resource-use partitioning among coexisting tree species as well as forest responses to drought.However,knowled...Understanding water uptake depth and its relationship with functional traits offers valuable insights into resource-use partitioning among coexisting tree species as well as forest responses to drought.However,knowledge about water uptake patterns in vertical soil layers,especially among increasingly widespread secondary forest tree species,remains limited.In this study,we investigated interspecific and seasonal variations in water uptake depth among seven coexisting tree species over a 2-year period in a warm-temperate secondary forest in central Japan.We also analyzed the relationships of water uptake depth with tree height and functional traits,including specific leaf area(SLA),leaf dry matter content(LDMC),leaf nitrogen(N)content,and wood density(WD),to discern resource-use and-acquisition strategies.Results revealed that taller trees,especially when soil water is scarce,tend to access deeper soil water sources,indicating that water source partitioning is correlated with tree height.This interspecific and temporal variation in water sources likely stratifies trees to facilitate coexistence within the forest.Water uptake depth was primarily associated with WD and LDMC:trees absorbing more water from shallow soils during dry conditions exhibited lower WD and LDMC,indicating a proactive resource-use strategy.Conversely,SLA and leaf N content were orthogonal to water uptake depth,suggesting that strategies for acquiring belowground and aboveground resources may differ.Considering the alternation of tree species composition during secondary forest succession,our study highlights the importance of further data collection regarding root water uptake depth along successional stages to understand dynamic shifts in water uptake sources.展开更多
A field experiment using PVC growth tubes was conducted in the Loess Plateau of China to determine the effective root depth(ERD)of winter wheat and its relationship with root distributions and soil water conditions.Th...A field experiment using PVC growth tubes was conducted in the Loess Plateau of China to determine the effective root depth(ERD)of winter wheat and its relationship with root distributions and soil water conditions.The water stable isotopes technique was used to estimate the water uptake contributions of different root depths during the growth stages.On the basis of IsoSource and the Romero-Saltos model,the ERD was 0-40 cm in the majority of the growth stage.However,in the heading and filling stages,the ERD could reach 60%-75%of the maximum root depth.Furthermore,the contributions to water uptake of different root depths were correlated with variations in soil water and root length density(r=0.395 and 0.368,respectively;p<0.05).However,by path analysis,the low decisive coefficient indicated that root distribution and soil water content did not always follow the same trend as water uptake.The conclusions of this study can help with understanding winter wheat water uptake mechanisms in arid and semi-arid regions and increasing water use efficiency.展开更多
Aims Research on the effects of extreme rainfall events on ecosystem function has primarily focussed on drought or flooding events,which usually include changes to mean or total rainfall,annually or over a season.Howe...Aims Research on the effects of extreme rainfall events on ecosystem function has primarily focussed on drought or flooding events,which usually include changes to mean or total rainfall,annually or over a season.However,less is known about the effects of increased rainfall variability without change to mean or total amounts.We investigated the effects of increased variation of water supply on shoot and root biomass as well as the distribution of root biomass of four grassland plant species,grown in monoculture and mixture communities.Methods Perennial ryegrass(Lolium perenne L.,shallow-rooting grass),chicory(Cichorium intybus L.,deep-rooting forb),white clover(Trifolium repens L.,shallow-rooting legume)and red clover(Trifolium pratense L.,deep-rooting legume)were established in mesocosms.Four plants of the same species were grown in monoculture communities and one of each species grown in four-species communities.Water supply was manipulated such that;compared with a baseline level with low variation in water supply,there was a treatment with medium variation(±40%)and another with high variation(±80%).Shoot and root biomass were measured,and vertical root distribution models fitted.Important Findings Compared with the low variation treatment,shoot biomass was significantly reduced under high variation for white clover,red clover and four-species communities.Under all conditions,four-species communities produced more shoot and root biomass than predicted by species performance in monoculture(overyielding).Under increased water variation,chicory monocultures allocated a higher proportion of root biomass to deeper soil layers while the total root biomass of white clover monocultures was significantly reduced.These results indicate that increased variability of water supply can negatively affect the shoot and root biomass production of single and multi-species grasslands.There is a need for further investigation of water variation effects on the functioning of multi-species grassland systems at field scale.展开更多
Alhagi sparsifolia Shap. （Fabaceae） is a spiny, perennial herb. The species grows in the salinized, arid regions in North China. This study investigated the response characteristics of the root growth and the dis- t...Alhagi sparsifolia Shap. （Fabaceae） is a spiny, perennial herb. The species grows in the salinized, arid regions in North China. This study investigated the response characteristics of the root growth and the dis- tribution of one-year-old A. sparsifolia seedlings to different groundwater depths in controlled plots. The eco- logical adaptability of the root systems of A. sparsifolia seedlings was examined using the artificial digging method. Results showed that： （1） A. sparsifolia seedlings adapted to an increase in groundwater depth mainly through increasing the penetration depth and growth rate of vertical roots. The vertical roots grew rapidly when soil moisture content reached 3%-9%, but slowly when soil moisture content was 13%-20%. The vertical roots stopped growing when soil moisture content reached 30% （the critical soil moisture point）. （2） The morphological plasticity of roots is an important strategy used by A. sparsifolia seedlings to obtain water and adapt to dry soil conditions. When the groundwater table was shallow, horizontal roots quickly expanded and tillering increased in order to compete for light resources, whereas when the groundwater table was deeper, vertical roots developed quickly to exploit space in the deeper soil layers. （3） The decrease in groundwater depth was probably respon- sible for the root distribution in the shallow soil layers. Root biomass and surface area both decreased with soil depth. One strategy of A. sparsifolia seedlings in dealing with the increase in groundwater depth is to increase root biomass in the deep soil layers. The relationship between the root growth/distribution of A. sparsifolia and the depth of groundwater table can be used as guidance for harvesting A. sparsifolia biomass and managing water resources for forage grasses. It is also of ecological significance as it reveals how desert plants adapt to arid environments.展开更多
Climate change has significantly increased the frequency and severity of droughts and risk of tree death worldwide.Differences in leaf habit,plant size,and species diversity are associated with differences in the risk...Climate change has significantly increased the frequency and severity of droughts and risk of tree death worldwide.Differences in leaf habit,plant size,and species diversity are associated with differences in the risk of drought-induced mortality,but the relative contributions of these factors to the risk of mortality are unclear.In a study of the mortality of tree and shrub species during the extreme drought of 2019 in a savanna ecosystem in Southwest China,we assessed the relative contributions of evergreen and deciduous leaf habit,plant size,and species richness and diversity to the mortality of shrubs and trees after the 2019 extreme drought.The deciduous species had significantly lower hydraulic safety margins than the coexisting evergreen species,resulting in a higher mortality risk.Additionally,species and individuals with taller canopies tended to have deeper root systems,an advantage during extreme drought that reduced mortality risk.Notably,mortality risk was largely independent of stand species richness and diversity.Overall,leaf habit and plant height were better predictors of mortality risk than species richness and diversity.These novel insights provide a better understanding of the mechanisms driving drought-induced mortality in the ecosystems with a low canopy and weak interspecific and intraspecific competition for shared resources.Leaf habit and tree size should be incorporated into hypotheses on the mechanisms underlying drought-induced tree mortality.展开更多
Cellulosic bioethanol produced from non-edible plants reduces potential food-fuel competition and, as such, is receiving increasing attention. In the raw material production of cellulosic bioethanol, the aboveground b...Cellulosic bioethanol produced from non-edible plants reduces potential food-fuel competition and, as such, is receiving increasing attention. In the raw material production of cellulosic bioethanol, the aboveground biomass of plants is entirely harvested;consequently, the plant roots represent the major source of organic matter incorporated into the soil. We selected Erianthus and Napier grass as the raw materials for cultivation in Asia. However, information about whether these 2 species provide sufficient root volume to sustain soil fertility is limited. Therefore, we examined the spatial distribution of the roots of these 2 plants, and quantified root mass and length. Erianthus and Napier grass were either grown in fields or greenhouses in Tokyo (Japan) and Lampung (Indonesia), and then their roots were exposed from adjacent soil profiles. Both species developed large, deep roots, penetrating 2.0-2.6 m deep into the soil. Root depth indexes showed that the roots of both species penetrated much deeper into the soil compared to monocot crop species, being more comparable to dicot species. Erianthus developed a root mass and length of 384-850 g·m-2 and 28.8-35.8 km·m-2, while the values for Napier grass were 183-448 g·m-2 and 15.6-43.6 km·m-2, respectively. These values exceeded the maximum values previously recorded for common crop species. Our study confirmed that Erianthus and Napier grass develop deep root systems, with substantially large biomass;hence, we suggest that both plants supply root biomass in large quantities, representing possible major sources of soil organic matter.展开更多
Desert phreatophytes are greatly dependent on groundwater, but how their root systems adapt to different groundwater depths is poorly understood. In the present study, shoot and root growths of Alhagi sparsifolia Shap...Desert phreatophytes are greatly dependent on groundwater, but how their root systems adapt to different groundwater depths is poorly understood. In the present study, shoot and root growths of Alhagi sparsifolia Shap. seedlings were studied across a gradient of groundwater depths. Leaves, stems and roots of different orders were measured after 120 days of different groundwater treatments. Results indicated that the depth of soil wetting front and the vertical distribution of soil water contents were highly controlled by groundwater depths. The shoot growth and biomass of A. sparsifolia decreased, but the root growth and rooting depth increased under deeper groundwater conditions. The higher ratios of root biomass, root/shoot and root length/leaf area under deeper groundwater conditions implied that seedlings of A. sparsifolia economized carbon cost on their shoot growths. The roots of A. sparsifolia distributed evenly around the soil wetting fronts under deeper groundwater conditions. Root diameters and root lengths of all orders were correlated with soil water availabilities both within and among treatments. Seedlings of A. sparsifolia produced finer first- and second-order roots but larger third- and fourth-order roots in dry soils. The results demonstrated that the root systems of desert phreatophytes can be optimized to acquire groundwater resources and maximize seedling growth by balancing the costs of carbon gain.展开更多
Partitioning soil respiration into three components is vital to identify CO_2 sink or source and can help us better understand soil carbon dynamics. However, knowledge about the influences of soil depth and the primin...Partitioning soil respiration into three components is vital to identify CO_2 sink or source and can help us better understand soil carbon dynamics. However, knowledge about the influences of soil depth and the priming effect on soil respiration components under field has been limited. Three components of soil respiration（root respiration, rhizomicrobial respiration and basal respiration） in a plantation in the hilly area of the North China were separated by the 13 C natural abundance method. The results showed that the average proportions of rhizomicrobial respiration, root respiration and basal respiration at the 25-65 cm depths were about 14, 23 and 63 %, respectively. Three components of soil respiration varied with soil depth, and root respiration was the main component of soil respiration in deeper soil. The priming effect was obvious for the deep soil respiration, especially at the 40-50 cm depth. Thus, depth and priming effect should be taken into account to increase the accuracy of estimations of soil carbon flux.展开更多
基金supported by Japan Society for the Promotion of Science(JSPS)Grants-in-Aid for Scientific Research[Grant No.19H02992]Grant for the Environmental Research Projects,the Sumitomo Foundation[Grant No.2230116].
文摘Understanding water uptake depth and its relationship with functional traits offers valuable insights into resource-use partitioning among coexisting tree species as well as forest responses to drought.However,knowledge about water uptake patterns in vertical soil layers,especially among increasingly widespread secondary forest tree species,remains limited.In this study,we investigated interspecific and seasonal variations in water uptake depth among seven coexisting tree species over a 2-year period in a warm-temperate secondary forest in central Japan.We also analyzed the relationships of water uptake depth with tree height and functional traits,including specific leaf area(SLA),leaf dry matter content(LDMC),leaf nitrogen(N)content,and wood density(WD),to discern resource-use and-acquisition strategies.Results revealed that taller trees,especially when soil water is scarce,tend to access deeper soil water sources,indicating that water source partitioning is correlated with tree height.This interspecific and temporal variation in water sources likely stratifies trees to facilitate coexistence within the forest.Water uptake depth was primarily associated with WD and LDMC:trees absorbing more water from shallow soils during dry conditions exhibited lower WD and LDMC,indicating a proactive resource-use strategy.Conversely,SLA and leaf N content were orthogonal to water uptake depth,suggesting that strategies for acquiring belowground and aboveground resources may differ.Considering the alternation of tree species composition during secondary forest succession,our study highlights the importance of further data collection regarding root water uptake depth along successional stages to understand dynamic shifts in water uptake sources.
基金the National Natural Science Foundation of China(51579168)the Program for Science and Technology Development of Shanxi Province(20140311016-6)the Program for Graduate Student Education and Innovation of Shanxi Province(2016BY065).
文摘A field experiment using PVC growth tubes was conducted in the Loess Plateau of China to determine the effective root depth(ERD)of winter wheat and its relationship with root distributions and soil water conditions.The water stable isotopes technique was used to estimate the water uptake contributions of different root depths during the growth stages.On the basis of IsoSource and the Romero-Saltos model,the ERD was 0-40 cm in the majority of the growth stage.However,in the heading and filling stages,the ERD could reach 60%-75%of the maximum root depth.Furthermore,the contributions to water uptake of different root depths were correlated with variations in soil water and root length density(r=0.395 and 0.368,respectively;p<0.05).However,by path analysis,the low decisive coefficient indicated that root distribution and soil water content did not always follow the same trend as water uptake.The conclusions of this study can help with understanding winter wheat water uptake mechanisms in arid and semi-arid regions and increasing water use efficiency.
基金Funding was provided through the AnimalChange project which received funding from the European Community’s Seventh Framework Programme(grant agreement no.266018).
文摘Aims Research on the effects of extreme rainfall events on ecosystem function has primarily focussed on drought or flooding events,which usually include changes to mean or total rainfall,annually or over a season.However,less is known about the effects of increased rainfall variability without change to mean or total amounts.We investigated the effects of increased variation of water supply on shoot and root biomass as well as the distribution of root biomass of four grassland plant species,grown in monoculture and mixture communities.Methods Perennial ryegrass(Lolium perenne L.,shallow-rooting grass),chicory(Cichorium intybus L.,deep-rooting forb),white clover(Trifolium repens L.,shallow-rooting legume)and red clover(Trifolium pratense L.,deep-rooting legume)were established in mesocosms.Four plants of the same species were grown in monoculture communities and one of each species grown in four-species communities.Water supply was manipulated such that;compared with a baseline level with low variation in water supply,there was a treatment with medium variation(±40%)and another with high variation(±80%).Shoot and root biomass were measured,and vertical root distribution models fitted.Important Findings Compared with the low variation treatment,shoot biomass was significantly reduced under high variation for white clover,red clover and four-species communities.Under all conditions,four-species communities produced more shoot and root biomass than predicted by species performance in monoculture(overyielding).Under increased water variation,chicory monocultures allocated a higher proportion of root biomass to deeper soil layers while the total root biomass of white clover monocultures was significantly reduced.These results indicate that increased variability of water supply can negatively affect the shoot and root biomass production of single and multi-species grasslands.There is a need for further investigation of water variation effects on the functioning of multi-species grassland systems at field scale.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-EW-316)the National Natural Science Foundation of China (31070477,30870471)the West Light Foundation of the Chinese Academy of Sciences (XBBS201105)
文摘Alhagi sparsifolia Shap. （Fabaceae） is a spiny, perennial herb. The species grows in the salinized, arid regions in North China. This study investigated the response characteristics of the root growth and the dis- tribution of one-year-old A. sparsifolia seedlings to different groundwater depths in controlled plots. The eco- logical adaptability of the root systems of A. sparsifolia seedlings was examined using the artificial digging method. Results showed that： （1） A. sparsifolia seedlings adapted to an increase in groundwater depth mainly through increasing the penetration depth and growth rate of vertical roots. The vertical roots grew rapidly when soil moisture content reached 3%-9%, but slowly when soil moisture content was 13%-20%. The vertical roots stopped growing when soil moisture content reached 30% （the critical soil moisture point）. （2） The morphological plasticity of roots is an important strategy used by A. sparsifolia seedlings to obtain water and adapt to dry soil conditions. When the groundwater table was shallow, horizontal roots quickly expanded and tillering increased in order to compete for light resources, whereas when the groundwater table was deeper, vertical roots developed quickly to exploit space in the deeper soil layers. （3） The decrease in groundwater depth was probably respon- sible for the root distribution in the shallow soil layers. Root biomass and surface area both decreased with soil depth. One strategy of A. sparsifolia seedlings in dealing with the increase in groundwater depth is to increase root biomass in the deep soil layers. The relationship between the root growth/distribution of A. sparsifolia and the depth of groundwater table can be used as guidance for harvesting A. sparsifolia biomass and managing water resources for forage grasses. It is also of ecological significance as it reveals how desert plants adapt to arid environments.
基金supported by the National Natural Science Foundation of China(31600479,32371576)the Key R&D Program of Yunnan Province(202403AC100028)+1 种基金the Youth Academic and Technical Leading Talent Reserve Program in Yunnan Province(202405AC350012)the 14th Five-Year Plans of Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences(XTBG-1450101,E3ZKFF2B01).
文摘Climate change has significantly increased the frequency and severity of droughts and risk of tree death worldwide.Differences in leaf habit,plant size,and species diversity are associated with differences in the risk of drought-induced mortality,but the relative contributions of these factors to the risk of mortality are unclear.In a study of the mortality of tree and shrub species during the extreme drought of 2019 in a savanna ecosystem in Southwest China,we assessed the relative contributions of evergreen and deciduous leaf habit,plant size,and species richness and diversity to the mortality of shrubs and trees after the 2019 extreme drought.The deciduous species had significantly lower hydraulic safety margins than the coexisting evergreen species,resulting in a higher mortality risk.Additionally,species and individuals with taller canopies tended to have deeper root systems,an advantage during extreme drought that reduced mortality risk.Notably,mortality risk was largely independent of stand species richness and diversity.Overall,leaf habit and plant height were better predictors of mortality risk than species richness and diversity.These novel insights provide a better understanding of the mechanisms driving drought-induced mortality in the ecosystems with a low canopy and weak interspecific and intraspecific competition for shared resources.Leaf habit and tree size should be incorporated into hypotheses on the mechanisms underlying drought-induced tree mortality.
文摘Cellulosic bioethanol produced from non-edible plants reduces potential food-fuel competition and, as such, is receiving increasing attention. In the raw material production of cellulosic bioethanol, the aboveground biomass of plants is entirely harvested;consequently, the plant roots represent the major source of organic matter incorporated into the soil. We selected Erianthus and Napier grass as the raw materials for cultivation in Asia. However, information about whether these 2 species provide sufficient root volume to sustain soil fertility is limited. Therefore, we examined the spatial distribution of the roots of these 2 plants, and quantified root mass and length. Erianthus and Napier grass were either grown in fields or greenhouses in Tokyo (Japan) and Lampung (Indonesia), and then their roots were exposed from adjacent soil profiles. Both species developed large, deep roots, penetrating 2.0-2.6 m deep into the soil. Root depth indexes showed that the roots of both species penetrated much deeper into the soil compared to monocot crop species, being more comparable to dicot species. Erianthus developed a root mass and length of 384-850 g·m-2 and 28.8-35.8 km·m-2, while the values for Napier grass were 183-448 g·m-2 and 15.6-43.6 km·m-2, respectively. These values exceeded the maximum values previously recorded for common crop species. Our study confirmed that Erianthus and Napier grass develop deep root systems, with substantially large biomass;hence, we suggest that both plants supply root biomass in large quantities, representing possible major sources of soil organic matter.
基金supported by the Joint Funds of National Natural Science Foundation of China (U1203201)the National Natural Science Foundation of China (41371516, 31100144)
文摘Desert phreatophytes are greatly dependent on groundwater, but how their root systems adapt to different groundwater depths is poorly understood. In the present study, shoot and root growths of Alhagi sparsifolia Shap. seedlings were studied across a gradient of groundwater depths. Leaves, stems and roots of different orders were measured after 120 days of different groundwater treatments. Results indicated that the depth of soil wetting front and the vertical distribution of soil water contents were highly controlled by groundwater depths. The shoot growth and biomass of A. sparsifolia decreased, but the root growth and rooting depth increased under deeper groundwater conditions. The higher ratios of root biomass, root/shoot and root length/leaf area under deeper groundwater conditions implied that seedlings of A. sparsifolia economized carbon cost on their shoot growths. The roots of A. sparsifolia distributed evenly around the soil wetting fronts under deeper groundwater conditions. Root diameters and root lengths of all orders were correlated with soil water availabilities both within and among treatments. Seedlings of A. sparsifolia produced finer first- and second-order roots but larger third- and fourth-order roots in dry soils. The results demonstrated that the root systems of desert phreatophytes can be optimized to acquire groundwater resources and maximize seedling growth by balancing the costs of carbon gain.
基金supported by the National Natural Science Foundation of China(3157061731100322)+2 种基金Special Public Sector Research(GYHY20110400904)the Fundamental Research Funds for the Central Universities(NO.YX2011-19TD2011-07)
文摘Partitioning soil respiration into three components is vital to identify CO_2 sink or source and can help us better understand soil carbon dynamics. However, knowledge about the influences of soil depth and the priming effect on soil respiration components under field has been limited. Three components of soil respiration（root respiration, rhizomicrobial respiration and basal respiration） in a plantation in the hilly area of the North China were separated by the 13 C natural abundance method. The results showed that the average proportions of rhizomicrobial respiration, root respiration and basal respiration at the 25-65 cm depths were about 14, 23 and 63 %, respectively. Three components of soil respiration varied with soil depth, and root respiration was the main component of soil respiration in deeper soil. The priming effect was obvious for the deep soil respiration, especially at the 40-50 cm depth. Thus, depth and priming effect should be taken into account to increase the accuracy of estimations of soil carbon flux.
