The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform

Lucia R Dillenburg - One of the best experts on this subject based on the ideXlab platform.

  • leaf expansion and development of photosynthetic capacity and pigments in Liquidambar Styraciflua hamamelidaceae effects of uv b radiation
    American Journal of Botany, 1995
    Co-Authors: Lucia R Dillenburg, Joe H. Sullivan, Alan H Teramura
    Abstract:

    In order to perform their functions as photosynthetic organs, leaves must cope with excess heat and potentially damaging ultraviolet radiation. Possible increases in the UV-B portion of the solar spectrum may place an additional burden on leaves, and this could be particularly important for young expanding leaves with poorly developed UV-B defense mechanisms. We evaluated the effects of supplemental UV-B radiation on leaf expansion and the development of photosynthetic capacity and pigments in sweetgum (Liquidambar Styraciflua L.) seedlings. Seedlings were grown in the field under either ambient or ambient plus 3 or 5.0 kJ of biologically effective supplemental UV-B radiation. Although final leaf size was unaffected, the rate of leaf elongation and accumulation of leaf area was slower in leaves exposed to the lower supplemental UV-B irradiance. In contrast, chlorophyll accumulation and the development of photosynthetic capacity was more rapid in plants exposed to the higher, compared to the lower supplemental UV-B irradiance. The accumulation of anthocyanins and other putative flavonoids or UV-absorbing compounds was scarcely affected by exposure to supplemental UV-B radiation. These results suggest that the UV-B portion of the solar spectrum may, in the absence of gross affects on biomass, exert subtle influences on leaf ontogeny andmore » the development of photosynthetic pigments and capacity in sweetgum. 44 refs., 6 figs.« less

  • photosynthetic and biomass allocation responses of Liquidambar Styraciflua hamamelidaceae to vine competition
    American Journal of Botany, 1995
    Co-Authors: Lucia R Dillenburg, Alan H Teramura, Irwin N Forseth, Dennis F Whigham
    Abstract:

    This 2-year field study examined stomatal conductance, photosynthesis, and biomass allocation of Liquidambar Styraciflua saplings in response to below- and aboveground competition with the vines Lonicerajaponica and Parthenocissus quinquefolia. Vine competition did not affect stomatal conductance of the host trees. The leaf photosynthetic capacity and photosynthetic nitrogen-use efficiency were significantly reduced by root competition with vines, either singly or in combination with aboveground competition, early in the second growing season. However, such differences disappeared by the end of the second growing season. Trees competing below ground with vines also had lower allocation to leaves compared with stems. Aboveground competition with vines resulted in reduced photosynthetic capacity per unit leaf area, but not per unit leaf weight, in trees. No correlation was found between single leaf photosynthetic capacity and tree growth. In contrast, a high positive correlation existed between allocation to leaves and diameter growth. Results from this study suggest that allocation

  • effects of vine competition on availability of light water and nitrogen to a tree host Liquidambar Styraciflua
    American Journal of Botany, 1993
    Co-Authors: Lucia R Dillenburg, Alan H Teramura, Dennis F Whigham, Irwin N Forseth
    Abstract:

    Competitive effects of vines on their tree hosts are well documented, but the mechanisms involved in these interactions are poorly understood. The objectives of this study were to measure the effects of below- and/or aboveground competition from the vines Lonicera japonica and Parthenocissus quinquefolia on availability of light, water, and nitrogen to the host tree Liquidambar Styraciflua, and to examine the relationship between resource availability and tree growth. Light penetration through tree canopies, pre-dawn leaf water potential, and leaf nitrogen concentration were used as predictors of light, water, and nitrogen availability to the tree, respectively. Vine presence significantly reduced light penetration through the tree canopies, but this reduction was not clearly related to the growth responses of trees. Vines did not reduce the pre-dawn leaf water potential of competing trees, which was consistently above -0.5 MPa for the duration of the study. Leaf nitrogen concentration of trees, on the other hand, was significantly reduced by belowground competition with L. japonica. The positive correlation between the annual average leaf nitrogen concentration and tree diameter growth suggested that competition for nitrogen mediated the effects of belowground competition of vines on tree growth.

  • effects of below and aboveground competition from the vines lonicera japonica and parthenocissus quinquefolia on the growth of the tree host Liquidambar Styraciflua
    Oecologia, 1993
    Co-Authors: Lucia R Dillenburg, Dennis F Whigham, Aalan H Teramura, Irwin N Forseth
    Abstract:

    Detrimental effects of vines on tree growth in successional environments have been frequently reported. Little is known, however, about the relative importance of below and aboveground competition from vines on tree growth. The objective of this study was to quantify and compare the growth responses of Liquidambar Styraciflua saplings to below and/or aboveground competition with the exotic evergreen vine, Lonicera japonica (Japanese honeysuckle), and the native deciduous vine, Parthenocissus quinquefolia (Virginia creeper). Soil trenching and/or vine-trellising were used to control the type of vine competition experienced by trees. Comparisons among untrenched treatments tested for effects of belowground competition. Comparisons among trenched treatments tested for effects of aboveground competition. After two growing seasons, Lonicera japonica had a greater effect on the growth of L. Styraciflua than did P. quinquefolia. This effect was largely due to root competition, as canopy competition only had a negative effect on tree growth when it occurred in combination with root competition. Leaf expansion was consistently and similarly affected by all treatments which involved belowground competition.

Irwin N Forseth - One of the best experts on this subject based on the ideXlab platform.

  • photosynthetic and biomass allocation responses of Liquidambar Styraciflua hamamelidaceae to vine competition
    American Journal of Botany, 1995
    Co-Authors: Lucia R Dillenburg, Alan H Teramura, Irwin N Forseth, Dennis F Whigham
    Abstract:

    This 2-year field study examined stomatal conductance, photosynthesis, and biomass allocation of Liquidambar Styraciflua saplings in response to below- and aboveground competition with the vines Lonicerajaponica and Parthenocissus quinquefolia. Vine competition did not affect stomatal conductance of the host trees. The leaf photosynthetic capacity and photosynthetic nitrogen-use efficiency were significantly reduced by root competition with vines, either singly or in combination with aboveground competition, early in the second growing season. However, such differences disappeared by the end of the second growing season. Trees competing below ground with vines also had lower allocation to leaves compared with stems. Aboveground competition with vines resulted in reduced photosynthetic capacity per unit leaf area, but not per unit leaf weight, in trees. No correlation was found between single leaf photosynthetic capacity and tree growth. In contrast, a high positive correlation existed between allocation to leaves and diameter growth. Results from this study suggest that allocation

  • effects of vine competition on availability of light water and nitrogen to a tree host Liquidambar Styraciflua
    American Journal of Botany, 1993
    Co-Authors: Lucia R Dillenburg, Alan H Teramura, Dennis F Whigham, Irwin N Forseth
    Abstract:

    Competitive effects of vines on their tree hosts are well documented, but the mechanisms involved in these interactions are poorly understood. The objectives of this study were to measure the effects of below- and/or aboveground competition from the vines Lonicera japonica and Parthenocissus quinquefolia on availability of light, water, and nitrogen to the host tree Liquidambar Styraciflua, and to examine the relationship between resource availability and tree growth. Light penetration through tree canopies, pre-dawn leaf water potential, and leaf nitrogen concentration were used as predictors of light, water, and nitrogen availability to the tree, respectively. Vine presence significantly reduced light penetration through the tree canopies, but this reduction was not clearly related to the growth responses of trees. Vines did not reduce the pre-dawn leaf water potential of competing trees, which was consistently above -0.5 MPa for the duration of the study. Leaf nitrogen concentration of trees, on the other hand, was significantly reduced by belowground competition with L. japonica. The positive correlation between the annual average leaf nitrogen concentration and tree diameter growth suggested that competition for nitrogen mediated the effects of belowground competition of vines on tree growth.

  • effects of below and aboveground competition from the vines lonicera japonica and parthenocissus quinquefolia on the growth of the tree host Liquidambar Styraciflua
    Oecologia, 1993
    Co-Authors: Lucia R Dillenburg, Dennis F Whigham, Aalan H Teramura, Irwin N Forseth
    Abstract:

    Detrimental effects of vines on tree growth in successional environments have been frequently reported. Little is known, however, about the relative importance of below and aboveground competition from vines on tree growth. The objective of this study was to quantify and compare the growth responses of Liquidambar Styraciflua saplings to below and/or aboveground competition with the exotic evergreen vine, Lonicera japonica (Japanese honeysuckle), and the native deciduous vine, Parthenocissus quinquefolia (Virginia creeper). Soil trenching and/or vine-trellising were used to control the type of vine competition experienced by trees. Comparisons among untrenched treatments tested for effects of belowground competition. Comparisons among trenched treatments tested for effects of aboveground competition. After two growing seasons, Lonicera japonica had a greater effect on the growth of L. Styraciflua than did P. quinquefolia. This effect was largely due to root competition, as canopy competition only had a negative effect on tree growth when it occurred in combination with root competition. Leaf expansion was consistently and similarly affected by all treatments which involved belowground competition.

Richard B Thomas - One of the best experts on this subject based on the ideXlab platform.

  • reduced stomatal conductance in sweetgum Liquidambar Styraciflua sustained over long term co2 enrichment
    New Phytologist, 2004
    Co-Authors: Jeffrey D Herrick, Hafiz Maherali, Richard B Thomas
    Abstract:

    Summary • Over 4 yr (1998‐2001) we examined the effects of CO 2 enrichment on stomatal conductance ( g s ) of sun and shade leaves of overstory sweetgum ( Liquidambar Styraciflua ) grown at the Duke Forest Free Air Carbon CO 2 Enrichment (FACE) experiment. • Gas-exchange measurements were taken in June and September of each year and relationships between water stress and stomatal conductance were examined. Stomatal density was measured in June 2000. Relative stomatal limitation ( l g ) was calculated from gas-exchange measurements. •W e found a 28% reduction of g s in elevated CO 2 that was sustained over the study period and was similar in sun and shade leaves. Elevated CO 2 reduced l g by 26%. Stomatal density was not affected by CO 2 enrichment. Elevated CO 2 did not change the sensitivity of g s to soil moisture or vapor pressure deficit. • The data illustrate that decreased g s of sweetgum leaves in CO 2 enrichment is consistent over long periods of time and under varying environmental conditions.

  • Reduced stomatal conductance in sweetgum (Liquidambar Styraciflua) sustained over long‐term CO2 enrichment
    New Phytologist, 2004
    Co-Authors: Jeffrey D Herrick, Hafiz Maherali, Richard B Thomas
    Abstract:

    Summary • Over 4 yr (1998‐2001) we examined the effects of CO 2 enrichment on stomatal conductance ( g s ) of sun and shade leaves of overstory sweetgum ( Liquidambar Styraciflua ) grown at the Duke Forest Free Air Carbon CO 2 Enrichment (FACE) experiment. • Gas-exchange measurements were taken in June and September of each year and relationships between water stress and stomatal conductance were examined. Stomatal density was measured in June 2000. Relative stomatal limitation ( l g ) was calculated from gas-exchange measurements. •W e found a 28% reduction of g s in elevated CO 2 that was sustained over the study period and was similar in sun and shade leaves. Elevated CO 2 reduced l g by 26%. Stomatal density was not affected by CO 2 enrichment. Elevated CO 2 did not change the sensitivity of g s to soil moisture or vapor pressure deficit. • The data illustrate that decreased g s of sweetgum leaves in CO 2 enrichment is consistent over long periods of time and under varying environmental conditions.

  • leaf senescence and late season net photosynthesis of sun and shade leaves of overstory sweetgum Liquidambar Styraciflua grown in elevated and ambient carbon dioxide concentrations
    Tree Physiology, 2003
    Co-Authors: Jeffrey D Herrick, Richard B Thomas
    Abstract:

    We examined the effects of elevated CO 2 concentration ([CO 2 ]) on leaf demography, late-season photosynthesis and leaf N resorption of overstory sweetgum (Liquidambar Styraciflua L.) trees in the Duke Forest Free Air CO 2 Enrichment (FACE) experiment. Sun and shade leaves were subdivided into early leaves (formed in the overwintering bud) and late leaves (formed during the growing season). Overall, we found that leaf-level net photosynthetic rates were enhanced by atmospheric CO 2 enrichment throughout the season until early November; however, sun leaves showed a greater response to atmospheric CO 2 enrichment than shade leaves. Elevated [CO 2 ] did not affect leaf longevity, emergence date or abscission date of sun leaves or shade leaves. Leaf number and leaf area per shoot were unaffected by CO 2 treatment. A simple shoot photosynthesis model indicated that elevated [CO 2 ] stimulated photosynthesis by 60% in sun shoots, but by only 3% in shade shoots. Whole-shoot photosynthetic rate was more than 12 times greater in sun shoots than in shade shoots. In senescent leaves, elevated [CO 2 ] did not affect residual leaf nitrogen, and nitrogen resorption was largely unaffected by atmospheric CO 2 enrichment, except for a small decrease in shade leaves. Overall, elevated [CO 2 ] had little effect on the number of leaves per shoot at any time during the season and, therefore, did not change seasonal carbon gain by extending or shortening the growing season. Stimulation of carbon gain by atmospheric CO 2 enrichment in sweetgum trees growing in the Duke Forest FACE experiment was the result of a strong stimulation of photosynthesis throughout the growing season.

  • No photosynthetic down‐regulation in sweetgum trees (Liquidambar Styraciflua L.) after three years of CO2 enrichment at the Duke Forest FACE experiment
    Plant Cell and Environment, 2001
    Co-Authors: J D Herrick, Richard B Thomas
    Abstract:

    Photosynthetic capacity and leaf properties of sun and shade leaves of overstorey sweetgum trees (Liquidambar Styraciflua L.) were compared over the first 3 years of growth in ambient or ambient + 200 mL L -1 CO2 at the Duke Forest Free Air CO2 Enrichment (FACE) experiment. We were interested in whether photosynthetic downregulation to CO2 occurred in sweetgum trees growing in a forest ecosystem, whether shade leaves down-regulated to a greater extent than sun leaves, and if there was a seasonal component to photosynthetic down-regulation. During June and September of each year, we measured net photosynthesis (A) versus the calculated intercellular CO2 concentration (Ci) in situ and analysed these response curves using a biochemical model that described the limitations imposed by the amount and activity of ribulose-1,5bisphosphate carboxylase/oxygenase (Vcmax) and by the rate of ribulose-1,5-bisphosphate (RuBP) regeneration mediated by electron transport (Jmax). There was no evidence of photosynthetic down-regulation to CO2 in either sun or shade leaves of sweetgum trees over the 3 years of measurements. Elevated CO2 did not significantly affect Vcmax or Jmax. The ratio of Vcmax to Jmax was relatively constant, averaging 2·12, and was not affected by CO2 treatment, position in the canopy, or measurement period. Furthermore, CO2 enrichment did not affect leaf nitrogen per unit leaf area (Na), chlorophyll or total non-structural carbohydrates of sun or shade leaves. We did, however, find a strong relationship between Na and the modelled components of photosynthetic capacity, Vcmax and Jmax. Our data over the first 3 years of this experiment corroborate observations that trees rooted in the ground may not exhibit symptoms of photosynthetic down-regulation as quickly as tree seedlings growing in pots. There was a strong sustained enhancement of photosynthesis by CO2 enrichment whereby light-saturated net photosynthesis of sun leaves was stimulated by 63% and light-saturated net photosynthesis of shade leaves was stimulated by 48% when averaged over the 3 years. This study suggests that this CO2

  • no photosynthetic down regulation in sweetgum trees Liquidambar Styraciflua l after three years of co2 enrichment at the duke forest face experiment
    Plant Cell and Environment, 2001
    Co-Authors: J D Herrick, Richard B Thomas
    Abstract:

    Photosynthetic capacity and leaf properties of sun and shade leaves of overstorey sweetgum trees (Liquidambar Styraciflua L.) were compared over the first 3 years of growth in ambient or ambient + 200 mL L -1 CO2 at the Duke Forest Free Air CO2 Enrichment (FACE) experiment. We were interested in whether photosynthetic downregulation to CO2 occurred in sweetgum trees growing in a forest ecosystem, whether shade leaves down-regulated to a greater extent than sun leaves, and if there was a seasonal component to photosynthetic down-regulation. During June and September of each year, we measured net photosynthesis (A) versus the calculated intercellular CO2 concentration (Ci) in situ and analysed these response curves using a biochemical model that described the limitations imposed by the amount and activity of ribulose-1,5bisphosphate carboxylase/oxygenase (Vcmax) and by the rate of ribulose-1,5-bisphosphate (RuBP) regeneration mediated by electron transport (Jmax). There was no evidence of photosynthetic down-regulation to CO2 in either sun or shade leaves of sweetgum trees over the 3 years of measurements. Elevated CO2 did not significantly affect Vcmax or Jmax. The ratio of Vcmax to Jmax was relatively constant, averaging 2·12, and was not affected by CO2 treatment, position in the canopy, or measurement period. Furthermore, CO2 enrichment did not affect leaf nitrogen per unit leaf area (Na), chlorophyll or total non-structural carbohydrates of sun or shade leaves. We did, however, find a strong relationship between Na and the modelled components of photosynthetic capacity, Vcmax and Jmax. Our data over the first 3 years of this experiment corroborate observations that trees rooted in the ground may not exhibit symptoms of photosynthetic down-regulation as quickly as tree seedlings growing in pots. There was a strong sustained enhancement of photosynthesis by CO2 enrichment whereby light-saturated net photosynthesis of sun leaves was stimulated by 63% and light-saturated net photosynthesis of shade leaves was stimulated by 48% when averaged over the 3 years. This study suggests that this CO2

Dennis F Whigham - One of the best experts on this subject based on the ideXlab platform.

  • photosynthetic and biomass allocation responses of Liquidambar Styraciflua hamamelidaceae to vine competition
    American Journal of Botany, 1995
    Co-Authors: Lucia R Dillenburg, Alan H Teramura, Irwin N Forseth, Dennis F Whigham
    Abstract:

    This 2-year field study examined stomatal conductance, photosynthesis, and biomass allocation of Liquidambar Styraciflua saplings in response to below- and aboveground competition with the vines Lonicerajaponica and Parthenocissus quinquefolia. Vine competition did not affect stomatal conductance of the host trees. The leaf photosynthetic capacity and photosynthetic nitrogen-use efficiency were significantly reduced by root competition with vines, either singly or in combination with aboveground competition, early in the second growing season. However, such differences disappeared by the end of the second growing season. Trees competing below ground with vines also had lower allocation to leaves compared with stems. Aboveground competition with vines resulted in reduced photosynthetic capacity per unit leaf area, but not per unit leaf weight, in trees. No correlation was found between single leaf photosynthetic capacity and tree growth. In contrast, a high positive correlation existed between allocation to leaves and diameter growth. Results from this study suggest that allocation

  • effects of vine competition on availability of light water and nitrogen to a tree host Liquidambar Styraciflua
    American Journal of Botany, 1993
    Co-Authors: Lucia R Dillenburg, Alan H Teramura, Dennis F Whigham, Irwin N Forseth
    Abstract:

    Competitive effects of vines on their tree hosts are well documented, but the mechanisms involved in these interactions are poorly understood. The objectives of this study were to measure the effects of below- and/or aboveground competition from the vines Lonicera japonica and Parthenocissus quinquefolia on availability of light, water, and nitrogen to the host tree Liquidambar Styraciflua, and to examine the relationship between resource availability and tree growth. Light penetration through tree canopies, pre-dawn leaf water potential, and leaf nitrogen concentration were used as predictors of light, water, and nitrogen availability to the tree, respectively. Vine presence significantly reduced light penetration through the tree canopies, but this reduction was not clearly related to the growth responses of trees. Vines did not reduce the pre-dawn leaf water potential of competing trees, which was consistently above -0.5 MPa for the duration of the study. Leaf nitrogen concentration of trees, on the other hand, was significantly reduced by belowground competition with L. japonica. The positive correlation between the annual average leaf nitrogen concentration and tree diameter growth suggested that competition for nitrogen mediated the effects of belowground competition of vines on tree growth.

  • effects of below and aboveground competition from the vines lonicera japonica and parthenocissus quinquefolia on the growth of the tree host Liquidambar Styraciflua
    Oecologia, 1993
    Co-Authors: Lucia R Dillenburg, Dennis F Whigham, Aalan H Teramura, Irwin N Forseth
    Abstract:

    Detrimental effects of vines on tree growth in successional environments have been frequently reported. Little is known, however, about the relative importance of below and aboveground competition from vines on tree growth. The objective of this study was to quantify and compare the growth responses of Liquidambar Styraciflua saplings to below and/or aboveground competition with the exotic evergreen vine, Lonicera japonica (Japanese honeysuckle), and the native deciduous vine, Parthenocissus quinquefolia (Virginia creeper). Soil trenching and/or vine-trellising were used to control the type of vine competition experienced by trees. Comparisons among untrenched treatments tested for effects of belowground competition. Comparisons among trenched treatments tested for effects of aboveground competition. After two growing seasons, Lonicera japonica had a greater effect on the growth of L. Styraciflua than did P. quinquefolia. This effect was largely due to root competition, as canopy competition only had a negative effect on tree growth when it occurred in combination with root competition. Leaf expansion was consistently and similarly affected by all treatments which involved belowground competition.

Alan H Teramura - One of the best experts on this subject based on the ideXlab platform.

  • leaf expansion and development of photosynthetic capacity and pigments in Liquidambar Styraciflua hamamelidaceae effects of uv b radiation
    American Journal of Botany, 1995
    Co-Authors: Lucia R Dillenburg, Joe H. Sullivan, Alan H Teramura
    Abstract:

    In order to perform their functions as photosynthetic organs, leaves must cope with excess heat and potentially damaging ultraviolet radiation. Possible increases in the UV-B portion of the solar spectrum may place an additional burden on leaves, and this could be particularly important for young expanding leaves with poorly developed UV-B defense mechanisms. We evaluated the effects of supplemental UV-B radiation on leaf expansion and the development of photosynthetic capacity and pigments in sweetgum (Liquidambar Styraciflua L.) seedlings. Seedlings were grown in the field under either ambient or ambient plus 3 or 5.0 kJ of biologically effective supplemental UV-B radiation. Although final leaf size was unaffected, the rate of leaf elongation and accumulation of leaf area was slower in leaves exposed to the lower supplemental UV-B irradiance. In contrast, chlorophyll accumulation and the development of photosynthetic capacity was more rapid in plants exposed to the higher, compared to the lower supplemental UV-B irradiance. The accumulation of anthocyanins and other putative flavonoids or UV-absorbing compounds was scarcely affected by exposure to supplemental UV-B radiation. These results suggest that the UV-B portion of the solar spectrum may, in the absence of gross affects on biomass, exert subtle influences on leaf ontogeny andmore » the development of photosynthetic pigments and capacity in sweetgum. 44 refs., 6 figs.« less

  • photosynthetic and biomass allocation responses of Liquidambar Styraciflua hamamelidaceae to vine competition
    American Journal of Botany, 1995
    Co-Authors: Lucia R Dillenburg, Alan H Teramura, Irwin N Forseth, Dennis F Whigham
    Abstract:

    This 2-year field study examined stomatal conductance, photosynthesis, and biomass allocation of Liquidambar Styraciflua saplings in response to below- and aboveground competition with the vines Lonicerajaponica and Parthenocissus quinquefolia. Vine competition did not affect stomatal conductance of the host trees. The leaf photosynthetic capacity and photosynthetic nitrogen-use efficiency were significantly reduced by root competition with vines, either singly or in combination with aboveground competition, early in the second growing season. However, such differences disappeared by the end of the second growing season. Trees competing below ground with vines also had lower allocation to leaves compared with stems. Aboveground competition with vines resulted in reduced photosynthetic capacity per unit leaf area, but not per unit leaf weight, in trees. No correlation was found between single leaf photosynthetic capacity and tree growth. In contrast, a high positive correlation existed between allocation to leaves and diameter growth. Results from this study suggest that allocation

  • effects of vine competition on availability of light water and nitrogen to a tree host Liquidambar Styraciflua
    American Journal of Botany, 1993
    Co-Authors: Lucia R Dillenburg, Alan H Teramura, Dennis F Whigham, Irwin N Forseth
    Abstract:

    Competitive effects of vines on their tree hosts are well documented, but the mechanisms involved in these interactions are poorly understood. The objectives of this study were to measure the effects of below- and/or aboveground competition from the vines Lonicera japonica and Parthenocissus quinquefolia on availability of light, water, and nitrogen to the host tree Liquidambar Styraciflua, and to examine the relationship between resource availability and tree growth. Light penetration through tree canopies, pre-dawn leaf water potential, and leaf nitrogen concentration were used as predictors of light, water, and nitrogen availability to the tree, respectively. Vine presence significantly reduced light penetration through the tree canopies, but this reduction was not clearly related to the growth responses of trees. Vines did not reduce the pre-dawn leaf water potential of competing trees, which was consistently above -0.5 MPa for the duration of the study. Leaf nitrogen concentration of trees, on the other hand, was significantly reduced by belowground competition with L. japonica. The positive correlation between the annual average leaf nitrogen concentration and tree diameter growth suggested that competition for nitrogen mediated the effects of belowground competition of vines on tree growth.