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James R Ehleringer - One of the best experts on this subject based on the ideXlab platform.
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gender specific patterns of aboveground allocation canopy conductance and water use in a dominant riparian tree species Acer Negundo
Tree Physiology, 2008Co-Authors: Kevin R Hultine, S E Bush, Adam G West, K G Burtch, Diane E Pataki, James R EhleringerAbstract:Acer Negundo Sarg. (box elder) is a dioecious tree species that dominates riparian systems at mid elevations throughout the southwest and Intermountain West of the United States. Previous studies have shown that female A. Negundo trees occur at higher frequencies along stream margins, whereas males occur at higher frequencies in drier microsites. To better understand the adaptive significance of sex ratio biases and their impact on the ecohydrology of riparian ecosystems, we examined whole-plant water relations and hydraulic properties of mature male and female A. Negundo trees occurring within 1 m of a perennial stream channel. We hypothesized that (1) females would have significantly greater canopy water fluxes than males (particularly during periods of seed production: May-June), and (2) xylem in females is more hydraulically efficient but more vulnerable to cavitation than xylem in males. Mean sap flux density (J(s)) during the early growing season (May and June) was 43% higher in female trees than in male trees (n = 6 and 7 trees respectively, P < 0.0001). Mean J(s) in July and August remained 17% higher in females than in males (P = 0.0009). Mean canopy stomatal conductance per unit leaf area (g(s,leaf)) in May and June was on average 140% higher in females than in males (P < 0.0001). Mean g(s,leaf) in July and August remained 69% higher in female trees than in male trees (P < 0.0001). Canopy stomatal conductance scaled to basal area was 90 and 31% higher in females relative to males during May-June and July-August, respectively (P < 0.0001 during both periods). Conversely, there were no apparent differences in either branch hydraulic conductance or branch xylem cavitation vulnerability between genders. These results improve our capacity to describe the adaptive forces that shape the spatial distribution of male and female trees in dioecious species, and their consequences for ecohydrological processes in riparian ecosystems.
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effect of gender on sap flux scaled transpiration in a dominant riparian tree species box elder Acer Negundo
Journal of Geophysical Research, 2007Co-Authors: Kevin R Hultine, S E Bush, Adam G West, James R EhleringerAbstract:[1] Acer Negundo is a dioecious riparian tree species with a spatial segregation of the sexes along soil moisture gradients. Females are typically more common in wet sites along streams (typically F/M � 1.6), whereas males are more common in drier sites away from streams (typically F/M � 0.6). Spatial segregation between sexes may develop because of the higher reproductive cost in females compared to males. If so, female Acer Negundo trees would be under stronger selection to maximize resource uptake, and would therefore likely occur at greater frequencies in high resources sites (i.e., along streamsides), and increase rates of resource acquisition (i.e., water and nutrients). The spatial segregation of the sexes leads to the hypothesis that male and female individuals have varying influence on ecosystem evapotranspiration. To address this, stem sap flux was measured on mature streamside (� 1 m from stream channel) and nonstreamside (>1 m from stream channel) male and female Acer Negundo trees occurring in Red Butte Canyon near Salt Lake City, Utah, during the 2004 growing season. Despite having similar predawn and midday water potentials, sap flux density was 76% higher in streamside female trees than in males (P < 0.0001), while sap flux density was 19% greater in nonstreamside female trees compared to males (P < 0.0001). Mean daily sap flux density of all A. Negundo populations was highly correlated with mean daily vapor pressure deficit (P < 0.0001), and was moderately correlated with mean daily photosynthetic active radiation (P = 0.0263). At the watershed scale, nonstreamside male and female A. Negundo trees contributed 20 and 21% respectively to the estimated 1.7 mm d � 1 transpiration flux from dominant riparian vegetation away from streamsides (estimated from scaled sap flux measurements of all dominant riparian tree species in Red Butte Canyon). Male and female A. Negundo trees contributed 31 and 46% respectively of the estimated 8.0 mm d � 1 transpiration flux from dominant riparian vegetation adjacent to the stream channel. Results from this investigation show that the population structure of dioecious riparian trees has direct consequences on ecosystem ET, particularly along stream margins. Shifts in population structure therefore, may have profound impacts on several ecohydrological processes including stream discharge, biogeochemical cycling, and ecosystem productivity.
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temporal scaling of physiological responses from gas exchange to tree rings a gender specific study of Acer Negundo boxelder growing under different conditions
Functional Ecology, 2004Co-Authors: Todd E Dawson, Joy K Ward, James R EhleringerAbstract:Summary 1. Plant responses to water availability may change over time due to seasonality, interannual variation and developmental changes. Our past investigations demonstrated that male and female Boxelder ( Acer Negundo ) exhibit differences in their responses to water availability. Here we use the genders as a model system to: (1) examine if cultural conditions have an effect on instantaneous gas exchange and time-integrated carbon isotope discrimination ( ∆ ); (2) compare these physiological responses across a range of temporal scales (seasonal, annual, interannual); and (3) describe the responses of the genders at different ages to water availability. 2. Under well watered conditions, differences in instantaneous leaf gas exchange and ∆ were observed between the genders at all developmental stages. Within a gender, ∆ was similar throughout the growing season and between years, indicating a conserved physiological set-point despite changing growth conditions. When water stress was imposed, females exhibited greater reductions in photosynthetic rate and higher stomatal limitations to photosynthesis than males. 3. For well watered plants, a strong correlation existed between time-integrated intercellular leaf [CO 2 ] calculated from ∆ ( \ i ) and c i obtained from instantaneous gas exchange. However, when drought was imposed this correlation weakened in males and was non-existent in females. 4. This study indicates that instantaneous gas exchange and integrated ∆ values can be used to characterize leaf-level responses to water availability when growth conditions are relatively constant. However, when water availability fluctuates, care must be taken in equating these measurements because changing conditions may decouple responses integrating different time-scales, and the degree of this decoupling may vary even at the subspecies (gender) level.
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responses of Acer Negundo genders to interannual differences in water availability determined from carbon isotope ratios of tree ring cellulose
Tree Physiology, 2002Co-Authors: Joy K Ward, Todd E Dawson, James R EhleringerAbstract:Understanding the responses of riparian trees to water availability is critical for predicting the effects of changes in precipitation on riparian ecosystems. Dioecious Acer Negundo L. (box elder) is a common riparian tree that is highly sensitive to water stress. Earlier studies indicated that the genders of A. Negundo respond differently to water availability, with males being more conservative in their water use than females. To assess the potential effects of changes in precipitation on the sex ratio of riparian trees, we extended earlier studies of A. Negundo by analyzing responses of male and female genotypes to interannual differences in water availability in a common garden. We measured growth of tree rings and used stable carbon isotope analysis of tree ring alpha-cellulose to integrate physiological responses to annual water treatments. During dry years, male and female trees exhibited similar growth and physiological responses. However, during wet years, females exhibited higher growth rates and lower carbon isotope ratios (indicating less conservative water use) than did males. Furthermore, we found that male trees exhibited similar stomatal behavior (inferred from integrated carbon isotope ratios) whether years were wet or dry, whereas females did not exhibit a consistent response to changes in water availability. We predict that with increasing precipitation and soil water availability, the representation of females will be favored because of shifts in the competitive interactions of the genders. Such changes may affect the reproductive output of these riparian trees and may influence overall water flux from riparian ecosystems. In addition, this study demonstrates the utility of carbon isotope analysis for assessing long-term responses of tree populations to shifts in water availability.
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gender specific physiology carbon isotope discrimination and habitat distribution in boxelder Acer Negundo
Ecology, 1993Co-Authors: Todd E Dawson, James R EhleringerAbstract:In the semiarid Intermountain West, boxelder, Acer Negundo var. interior, a deciduous, dioecious tree, exhibits significant habitat-specific sex ratio biases. Although the overall sex ratio (male/female) does not deviate significantly from one, the sex ratio is significantly male biased (1.62) in drought-prone habitats, while it is significantly female biased (0.65) in moist, streamside habitats. The causes underlying gender-specific habitat associations in this species are not known. We hypothesized that spatial segregation of the sexes is maintained by differences in gender-specific photosynthetic behavior, water rela- tions characteristics, and both instantaneous and integrated water-use efficiency. Gender- specific physiological characteristics were measured and related to growth, reproduction, population age structure, and habitat distribution of male and female trees. Under both field and controlled-environment conditions, males and females differed significantly in a number of physiological traits. Males maintained lower stomatal con- ductance to water vapor (g), transpiration (E), net carbon assimilation (A), leaf internal CO2 concentration (ci), carbon isotope discrimination (AL; an index of time-integrated ci and water-use efficiency), and higher instantaneous (A/E) and long-term (A) water-use efficiency than females. Furthermore, male trees exhibited greater stomatal sensitivity to both declining soil water content and increasing leaf-to-air vapor pressure gradients, a measure of evaporative demand. Higher rates of carbon fixation in female trees were correlated with higher g, higher leaf nitrogen concentrations, and greater stomatal densities. For females growing in both wet and dry habitats, vegetative shoots had higher growth rates than reproductive shoots, while for males, growth rates of the two shoot types did not differ. In streamside habitats, female trees exhibited significantly greater vegetative shoot growth when compared to male trees. In contrast, males showed slightly greater vegetative and much greater reproductive shoot growth in non-streamside habitats. Re- gardless of habitat or growing conditions, females allocated proportionately more of their aboveground biomass to reproduction than did males. These results suggest that (1) gender-specific physiological traits can help explain the maintenance of habitat-specific sex ratio biases in A. Negundo along a soil moisture gradient, and (2) that the combination of the gender-specific physiology, growth, and allocation differences contribute to differences in the size (=age) structure of male and female plants within the population. Gender-specific physiological differences may have evolved as a product of selection to meet significantly different costs associated with reproduction in male and female plants.
Kevin R Hultine - One of the best experts on this subject based on the ideXlab platform.
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gender specific patterns of aboveground allocation canopy conductance and water use in a dominant riparian tree species Acer Negundo
Tree Physiology, 2008Co-Authors: Kevin R Hultine, S E Bush, Adam G West, K G Burtch, Diane E Pataki, James R EhleringerAbstract:Acer Negundo Sarg. (box elder) is a dioecious tree species that dominates riparian systems at mid elevations throughout the southwest and Intermountain West of the United States. Previous studies have shown that female A. Negundo trees occur at higher frequencies along stream margins, whereas males occur at higher frequencies in drier microsites. To better understand the adaptive significance of sex ratio biases and their impact on the ecohydrology of riparian ecosystems, we examined whole-plant water relations and hydraulic properties of mature male and female A. Negundo trees occurring within 1 m of a perennial stream channel. We hypothesized that (1) females would have significantly greater canopy water fluxes than males (particularly during periods of seed production: May-June), and (2) xylem in females is more hydraulically efficient but more vulnerable to cavitation than xylem in males. Mean sap flux density (J(s)) during the early growing season (May and June) was 43% higher in female trees than in male trees (n = 6 and 7 trees respectively, P < 0.0001). Mean J(s) in July and August remained 17% higher in females than in males (P = 0.0009). Mean canopy stomatal conductance per unit leaf area (g(s,leaf)) in May and June was on average 140% higher in females than in males (P < 0.0001). Mean g(s,leaf) in July and August remained 69% higher in female trees than in male trees (P < 0.0001). Canopy stomatal conductance scaled to basal area was 90 and 31% higher in females relative to males during May-June and July-August, respectively (P < 0.0001 during both periods). Conversely, there were no apparent differences in either branch hydraulic conductance or branch xylem cavitation vulnerability between genders. These results improve our capacity to describe the adaptive forces that shape the spatial distribution of male and female trees in dioecious species, and their consequences for ecohydrological processes in riparian ecosystems.
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effect of gender on sap flux scaled transpiration in a dominant riparian tree species box elder Acer Negundo
Journal of Geophysical Research, 2007Co-Authors: Kevin R Hultine, S E Bush, Adam G West, James R EhleringerAbstract:[1] Acer Negundo is a dioecious riparian tree species with a spatial segregation of the sexes along soil moisture gradients. Females are typically more common in wet sites along streams (typically F/M � 1.6), whereas males are more common in drier sites away from streams (typically F/M � 0.6). Spatial segregation between sexes may develop because of the higher reproductive cost in females compared to males. If so, female Acer Negundo trees would be under stronger selection to maximize resource uptake, and would therefore likely occur at greater frequencies in high resources sites (i.e., along streamsides), and increase rates of resource acquisition (i.e., water and nutrients). The spatial segregation of the sexes leads to the hypothesis that male and female individuals have varying influence on ecosystem evapotranspiration. To address this, stem sap flux was measured on mature streamside (� 1 m from stream channel) and nonstreamside (>1 m from stream channel) male and female Acer Negundo trees occurring in Red Butte Canyon near Salt Lake City, Utah, during the 2004 growing season. Despite having similar predawn and midday water potentials, sap flux density was 76% higher in streamside female trees than in males (P < 0.0001), while sap flux density was 19% greater in nonstreamside female trees compared to males (P < 0.0001). Mean daily sap flux density of all A. Negundo populations was highly correlated with mean daily vapor pressure deficit (P < 0.0001), and was moderately correlated with mean daily photosynthetic active radiation (P = 0.0263). At the watershed scale, nonstreamside male and female A. Negundo trees contributed 20 and 21% respectively to the estimated 1.7 mm d � 1 transpiration flux from dominant riparian vegetation away from streamsides (estimated from scaled sap flux measurements of all dominant riparian tree species in Red Butte Canyon). Male and female A. Negundo trees contributed 31 and 46% respectively of the estimated 8.0 mm d � 1 transpiration flux from dominant riparian vegetation adjacent to the stream channel. Results from this investigation show that the population structure of dioecious riparian trees has direct consequences on ecosystem ET, particularly along stream margins. Shifts in population structure therefore, may have profound impacts on several ecohydrological processes including stream discharge, biogeochemical cycling, and ecosystem productivity.
Richard Michalet - One of the best experts on this subject based on the ideXlab platform.
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invasive Acer Negundo outperforms native species in non limiting resource environments due to its higher phenotypic plasticity
BMC Ecology, 2011Co-Authors: Richard Michalet, Annabel J Porte, Laurent J Lamarque, Christopher J Lortie, Sylvain DelzonAbstract:Background To identify the determinants of invasiveness, comparisons of traits of invasive and native species are commonly performed. Invasiveness is generally linked to higher values of reproductive, physiological and growth-related traits of the invasives relative to the natives in the introduced range. Phenotypic plasticity of these traits has also been cited to increase the success of invasive species but has been little studied in invasive tree species. In a greenhouse experiment, we compared ecophysiological traits between an invasive species to Europe, Acer Negundo, and early- and late-successional co-occurring native species, under different light, nutrient availability and disturbance regimes. We also compared species of the same species groups insitu, in riparian forests.
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challenging growth survival trade off a key for Acer Negundo invasion in european floodplains
Canadian Journal of Forest Research, 2010Co-Authors: Patrick Saccone, Jeanjacques Brun, Richard MichaletAbstract:We compared the performances of juvenile Acer Negundo with those of native species to assess how this species has invaded intermediate habitats along European riparian successional gradients. In th...
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Acer Negundo invasion along a successional gradient early direct facilitation by native pioneers and late indirect facilitation by conspecifics
New Phytologist, 2010Co-Authors: Patrick Saccone, Jeanjacques Brun, Jean Philippe Pages, Jacky Girel, Richard MichaletAbstract:*Here, we analysed the role of direct and indirect plant interactions in the invasion process of Acer Negundo along a natural successional gradient in the Middle Rhone floodplain (France). We addressed two questions: What are the responses of the invasive Acer seedlings to native communities' effects along the successional gradient? What are the effects of the invasive Acer adult trees on the native communities? *In the three communities (Salix, Acer and Fraxinus stands) we transplanted juveniles of the invasive and juveniles of the natives within the forest and in experimental gaps, and with and without the herb layer. We also quantified changes in understory functional composition, light, nitrogen and moisture among treatments. *Acer seedlings were directly facilitated for survival in the Salix and Acer communities and indirectly facilitated for growth by adult Acer through the reduction of the abundance of highly competitive herbaceous competitors. *We conclude that direct facilitation by the tree canopy of the native pioneer Salix is very likely the main biotic process that induced colonization of the invasive Acer in the floodplain and that indirect facilitation by adult conspecifics contributed to population establishment.
Sylvain Delzon - One of the best experts on this subject based on the ideXlab platform.
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Killing it softly: girdling as an efficient eco-friendly method to locally remove invasive Acer Negundo
Ecological Restoration North America, 2016Co-Authors: Nastasia R. Merceron, Sylvain Delzon, Laurent J Lamarque, Annabel J PorteAbstract:Acer Negundo (boxelder maple) is a North American native tree species that currently invades riparian and disturbed areas in Europe, affecting both bank stability and ecosystem biodiversity. As a response to managers’ requests, we aimed at finding an eco-friendly method which would locally remove this species and help habitat restoration. Four control methods were tested on A. Negundo adults and saplings from stands located in three experimental sites along different watercourses in Southwestern France: girdling, low cutting, high cutting, and cutting followed by the application of juglone (a natural allelopathic substance from walnut tree leaves). Mortality and resprout production on the treated A. Negundo individuals were assessed during two years following the application of the control methods. Girdling was the most efficient method as it significantly induced higher mortality rates compared to the others (65 vs 15% of dead A. Negundo two years after treatment administration). When healing emerged on trunks, yearly repeated girdling was required to reach full success. None of the control methods significantly reduced resprout production; not even the application of juglone. Girdling is the most recommended method to kill and remove A. Negundo at a local scale in invaded natural habitats. Considering that A. Negundo benefits from increases in light availability to outcompete native species, we further recommend removing seedlings from understories when applying girdling on adult and sapling individuals in order to optimize restoration conditions in natural stands and improve native species re-establishment.
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A test for pre-adapted phenotypic plasticity in the invasive tree Acer Negundo L.
PLoS ONE, 2013Co-Authors: Laurent Lamarque L.j., Christopher J Lortie, Annabel Porte, Camille Eymeric, Jean-baptiste Lasnier, Sylvain DelzonAbstract:Phenotypic plasticity is a key mechanism associated with the spread of exotic plants and previous studies have found that invasive species are generally more plastic than co-occurring species. Comparatively, the evolution of phenotypic plasticity in plant invasion has received less attention, and in particular, the genetic basis of plasticity is largely unexamined. Native from North America, Acer Negundo L. is aggressively impacting the riparian forests of southern and eastern Europe thanks to higher plasticity relative to co-occurring native species. We therefore tested here whether invasive populations have evolved increased plasticity since introduction. The performance of 1152 seedlings from 8 native and 8 invasive populations was compared in response to nutrient availability. Irrespective of nutrients, invasive populations had higher growth and greater allocation to above-ground biomass relative to their native conspecifics. More importantly, invasive genotypes did not show increased plasticity in any of the 20 traits examined. This result suggests that the high magnitude of plasticity to nutrient variation of invasive seedlings might be pre-adapted in the native range. Invasiveness of A. Negundo could be explained by higher mean values of traits due to genetic differentiation rather than by evolution of increased plasticity.
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invasive Acer Negundo outperforms native species in non limiting resource environments due to its higher phenotypic plasticity
BMC Ecology, 2011Co-Authors: Richard Michalet, Annabel J Porte, Laurent J Lamarque, Christopher J Lortie, Sylvain DelzonAbstract:Background To identify the determinants of invasiveness, comparisons of traits of invasive and native species are commonly performed. Invasiveness is generally linked to higher values of reproductive, physiological and growth-related traits of the invasives relative to the natives in the introduced range. Phenotypic plasticity of these traits has also been cited to increase the success of invasive species but has been little studied in invasive tree species. In a greenhouse experiment, we compared ecophysiological traits between an invasive species to Europe, Acer Negundo, and early- and late-successional co-occurring native species, under different light, nutrient availability and disturbance regimes. We also compared species of the same species groups insitu, in riparian forests.
Adam G West - One of the best experts on this subject based on the ideXlab platform.
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gender specific patterns of aboveground allocation canopy conductance and water use in a dominant riparian tree species Acer Negundo
Tree Physiology, 2008Co-Authors: Kevin R Hultine, S E Bush, Adam G West, K G Burtch, Diane E Pataki, James R EhleringerAbstract:Acer Negundo Sarg. (box elder) is a dioecious tree species that dominates riparian systems at mid elevations throughout the southwest and Intermountain West of the United States. Previous studies have shown that female A. Negundo trees occur at higher frequencies along stream margins, whereas males occur at higher frequencies in drier microsites. To better understand the adaptive significance of sex ratio biases and their impact on the ecohydrology of riparian ecosystems, we examined whole-plant water relations and hydraulic properties of mature male and female A. Negundo trees occurring within 1 m of a perennial stream channel. We hypothesized that (1) females would have significantly greater canopy water fluxes than males (particularly during periods of seed production: May-June), and (2) xylem in females is more hydraulically efficient but more vulnerable to cavitation than xylem in males. Mean sap flux density (J(s)) during the early growing season (May and June) was 43% higher in female trees than in male trees (n = 6 and 7 trees respectively, P < 0.0001). Mean J(s) in July and August remained 17% higher in females than in males (P = 0.0009). Mean canopy stomatal conductance per unit leaf area (g(s,leaf)) in May and June was on average 140% higher in females than in males (P < 0.0001). Mean g(s,leaf) in July and August remained 69% higher in female trees than in male trees (P < 0.0001). Canopy stomatal conductance scaled to basal area was 90 and 31% higher in females relative to males during May-June and July-August, respectively (P < 0.0001 during both periods). Conversely, there were no apparent differences in either branch hydraulic conductance or branch xylem cavitation vulnerability between genders. These results improve our capacity to describe the adaptive forces that shape the spatial distribution of male and female trees in dioecious species, and their consequences for ecohydrological processes in riparian ecosystems.
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effect of gender on sap flux scaled transpiration in a dominant riparian tree species box elder Acer Negundo
Journal of Geophysical Research, 2007Co-Authors: Kevin R Hultine, S E Bush, Adam G West, James R EhleringerAbstract:[1] Acer Negundo is a dioecious riparian tree species with a spatial segregation of the sexes along soil moisture gradients. Females are typically more common in wet sites along streams (typically F/M � 1.6), whereas males are more common in drier sites away from streams (typically F/M � 0.6). Spatial segregation between sexes may develop because of the higher reproductive cost in females compared to males. If so, female Acer Negundo trees would be under stronger selection to maximize resource uptake, and would therefore likely occur at greater frequencies in high resources sites (i.e., along streamsides), and increase rates of resource acquisition (i.e., water and nutrients). The spatial segregation of the sexes leads to the hypothesis that male and female individuals have varying influence on ecosystem evapotranspiration. To address this, stem sap flux was measured on mature streamside (� 1 m from stream channel) and nonstreamside (>1 m from stream channel) male and female Acer Negundo trees occurring in Red Butte Canyon near Salt Lake City, Utah, during the 2004 growing season. Despite having similar predawn and midday water potentials, sap flux density was 76% higher in streamside female trees than in males (P < 0.0001), while sap flux density was 19% greater in nonstreamside female trees compared to males (P < 0.0001). Mean daily sap flux density of all A. Negundo populations was highly correlated with mean daily vapor pressure deficit (P < 0.0001), and was moderately correlated with mean daily photosynthetic active radiation (P = 0.0263). At the watershed scale, nonstreamside male and female A. Negundo trees contributed 20 and 21% respectively to the estimated 1.7 mm d � 1 transpiration flux from dominant riparian vegetation away from streamsides (estimated from scaled sap flux measurements of all dominant riparian tree species in Red Butte Canyon). Male and female A. Negundo trees contributed 31 and 46% respectively of the estimated 8.0 mm d � 1 transpiration flux from dominant riparian vegetation adjacent to the stream channel. Results from this investigation show that the population structure of dioecious riparian trees has direct consequences on ecosystem ET, particularly along stream margins. Shifts in population structure therefore, may have profound impacts on several ecohydrological processes including stream discharge, biogeochemical cycling, and ecosystem productivity.