ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Plant biology Water gate (2003)

Zwieniecki, Maciej A. ; Holbrook, N. Michele

[s.l.] : Nature Publishing Group

Nature 425 (2003), S. 361-361

add to mindlist on the mindlist

Details

ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] Plants are among the thirstiest of creatures. Of the more than 60 trillion tonnes of water that cycles each year from the land to the atmosphere, nearly two-thirds passes through the bodies of living land plants. Plants require these large amounts of water because their mode of acquiring carbon ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/425361a

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

2

Electronic Resource

Dynamic changes in petiole specific conductivity in red maple (Acer rubrum L.), tulip tree (Liriodendron tulipifera L.) and northern fox grape (Vitis labrusca L.) (2000)

Zwieniecki, Maciej A. ; Hutyra, Lucy ; Thompson, Matthew V. ; [et al.]

Oxford, UK : Blackwell Science Ltd

Plant, cell & environment 23 (2000), S. 0

add to mindlist on the mindlist

Details

ISSN: 1365-3040

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Diurnal variation in petiole specific hydraulic conductivity and simultaneous measurements of leaf water potential were recorded in red maple, tulip tree and fox grape. Petiole specific conductivity was determined from in situ measurements of water flow into the distal (leaf-bearing) end of an attached petiole as a function of applied hydrostatic pressure and petiole dimensions. The hydraulic properties of the petiole dominated the measurements, indicating that this technique can be used for rapid estimates of petiole hydraulic conductivity. There was a significant decrease in petiole specific conductivity associated with increasingly more negative leaf water potentials in maple and tulip tree, but not in grape. Petiole specific conductivity increased during the afternoon while the plant was actively transpiring and the xylem sap was under tension. The recovery of petiole conductivity during the afternoon suggests that hydraulic conductivity reflects a dynamic balance between a loss of hydraulic conductivity with increasing water stress, and its restoration as tension within the xylem decreases. Three experimental manipulations were applied to red maple and tulip tree to examine the sensitivity of diurnal changes in petiole conductivity to various physiological perturbations. Both phloem girdling and application of HgCl2 to the transpiration stream resulted in a marked decrease in the degree to which petiole specific conductivity recovered as xylem tension relaxed during the afternoon. Delivery of a surfactant to the xylem, however, did not significantly alter the relation between leaf water potential and petiole hydraulic conductivity.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-3040.2000.00554.x

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

3

Electronic Resource

The spatial pattern of air seeding thresholds in mature sugar maple trees (2005)

CHOAT, BRENDAN ; LAHR, ELEANOR C. ; MELCHER, PETER J. ; [et al.]

Oxford, UK : Blackwell Science Ltd

Plant, cell & environment 28 (2005), S. 0

add to mindlist on the mindlist

Details

ISSN: 1365-3040

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Air seeding threshold (Pa) of xylem vessels from current year growth rings were measured along the vertical axis of mature sugar maple trees (Acer saccharum Marsh.), with sampling points in primary leaf veins, petioles, 1-, 3-, and 7-year-old branches, large branches, the trunk and roots. The air seeding threshold was taken as the pressure required to force nitrogen gas through intervessel pit membranes. Although all measurements were made on wood produced in the same year, Pa varied between different regions of A. saccharum, with distal organs such as leaves and petioles having lower Pa than basal regions. Mean (SE) Pa ranged from 1.0 (± 0.1) MPa in primary leaf veins to 4.8 (± 0.1) MPa in the main trunk. Roots exhibited a Pa of 2.8 (± 0.2) MPa, lower than all other regions of the tree except leaf veins and petioles. Mean xylem vessel diameter increased basipetally, with the widest vessels occurring in the trunk and roots. Within the shoot, wider vessels had greater air seeding thresholds, contrasting with trends previously reported. However, further experimentation revealed that differences in Pa between regions of the stem were driven by the presence of primary xylem conduits, rather than differences in vessel diameter. In 1-year-old branches, Pa was significantly lower in primary xylem vessels than in adjacent secondary xylem vessels. This explained the lower values of Pa measured in petioles and leaf veins, which possessed a greater ratio of primary xylem to secondary xylem than other regions. The difference in Pa between primary and secondary xylem was attributed to the greater area of primary cell wall (pit membrane) exposed in primary xylem conduits with helical or annular thickening.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-3040.2005.01336.x

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

4

Electronic Resource

ELEVATED ATMOSPHERIC CO2 INCREASES WATER AVAILABILITY IN A WATER-LIMITED GRASSLAND ECOSYSTEM (1997)

Fredeen, Arthur L. ; Randerson, James T. ; Holbrook, N. Michele ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Journal of the American Water Resources Association 33 (1997), S. 0

add to mindlist on the mindlist

Details

ISSN: 1752-1688

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Architecture, Civil Engineering, Surveying , Geography

Notes: : Californian annual grassland on sandstone (moderately fertile) and serpentine (very infertile) soils at the Jasper Ridge Biological Preserve, Stanford, California, were exposed to ambient or elevated (ambient + 36 Pa CO2) atmospheric CO2 in open-top chambers since December 1991. We measured ecosystem evapotranspiration with open gas-exchange systems, and soil moisture with time-domain reflectometry (TDR) over 0–15 cm (serpentine) and 0–30 cm (sandstone) depths, at times of peak above ground physiological activity. Evapotranspiration decreased by 12 to 63 percent under elevated CO2 in three consecutive years in the sandstone ecosystem (p = 0.053, p = 0.162, p = 0.082 in 1992, 1993, and 1994, respectively). In correspondence with decreased evapotranspiration, late-season soil moisture reserves in the sandstone were extended temporally by 10 ± 3 days in 1993 and by 28 ± 11 days in 1994. The effect of elevated CO2 on soil moisture was greater in the drier spring of 1994 (419 mm annual rainfall) than in 1993 (905 mm annual rainfall). In the serpentine ecosystem, evapotranspiration and soil moisture reserves were not clearly affected by elevated CO2. Soil water may be conserved in drought-affected ecosystems exposed to elevated CO2, but the amount of conservation appears to depend on the relative importance of transpiration and soil evaporation in controlling water flux.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1752-1688.1997.tb04122.x

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

5

Electronic Resource

Seasonal patterns of acid fluctuations and resource storage in the arborescent cactus Opuntia excelsa in relation to light availability and size (1992)

Lerdau, Manuel T. ; Holbrook, N. Michele ; Mooney, Harold A. ; [et al.]

Springer

Oecologia 92 (1992), S. 166-171

add to mindlist on the mindlist

Details

ISSN: 1432-1939

Keywords: Crassulacean acid metabolism ; Light availability ; Opuntia excelsa ; Resource storage ; Tropical deciduous forest

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary We investigated relationships between light availability, diel acid fluctuation, and resource storage in the arborescent cactus Opuntia excelsa growing in western Mexico. We compared canopy and understory individuals from a deciduous forest as well as open-grown plants of the same approximate size as those in the understory. During the wet season light availability and daily fluctuations in titratable acidity (an index of carbon uptake) were lower in the understory than in unshaded habitats. In the dry season all plants had reduced levels of acid fluctuation, with the smallest individuals, regardless of habitat, showing the greatest reduction. These data suggest that light availability in the forest understory constrains carbon assimilation during the wet season, but that a factor associated with plant size, possibly water status, limits carbon gain during the dry season. Plants in all habitats remained physiologically active for at least five months into the dry season. We suggest that this was possible due to the maintenance of constant concentrations of water and nitrogen in the photosynthetically active chlorenchyma. Parenchyma in terminal cladodes showed a different seasonal pattern of resource storage; water content and nitrogen concentration were reduced from the wet to the dry season in the parenchyma. Using the parenchyma to supply photosynthetic tissues during times of reduced resource availability allows O. excelsa to assimilate carbon during times of the year when most other trees in the forest are leafless.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00317359

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

6

Electronic Resource

Regulation of water flux through trunks, branches, and leaves in trees of a lowland tropical forest (1998)

Andrade, José Luis ; Meinzer, Frederick C. ; Goldstein, Guillermo ; [et al.]

Springer

Oecologia 115 (1998), S. 463-471

add to mindlist on the mindlist

Details

ISSN: 1432-1939

Keywords: Key words Hydraulic conductance ; Sap flow ; Stomata ; Transpiration ; Tropical forest trees

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract We studied regulation of whole-tree water use in individuals of five diverse canopy tree species growing in a Panamanian seasonal forest. A construction crane equipped with a gondola was used to access the upper crowns and points along the branches and trunks of the study trees for making concurrent measurements of sap flow at the whole-tree and branch levels, and vapor phase conductances and water status at the leaf level. These measurements were integrated to assess physiological regulation of water use from the whole-tree to the single-leaf scale. Whole-tree water use ranged from 379 kg day−1 in a 35 m-tall Anacardium excelsum tree to 46 kg day−1 in an 18 m-tall Cecropia longipes tree. The dependence of whole-tree and branch sap velocity and sap flow on sapwood area was essentially identical in the five trees studied. However, large differences in transpiration per unit leaf area (E) among individuals and among branches on the same individual were observed. These differences were substantially reduced when E was normalized by the corresponding branch leaf area:sapwood area ratio (LA/SA). Variation in stomatal conductance (g s) and crown conductance (g c), a total vapor phase conductance that includes stomatal and boundary layer components, was closely associated with variation in the leaf area-specific total hydraulic conductance of the soil/leaf pathway (G t). Vapor phase conductance in all five trees responded similarly to variation in G t. Large diurnal variations in G t were associated with diurnal variation in exchange of water between the transpiration stream and internal stem storage compartments. Differences in stomatal regulation of transpiration on a leaf area basis appeared to be governed largely by tree size and hydraulic architectural features rather than physiological differences in the responsiveness of stomata. We suggest that reliance on measurements gathered at a single scale or inadequate range of scale may result in misleading conclusions concerning physiological differences in regulation of transpiration.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004420050542

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

7

Electronic Resource

Partitioning of soil water among canopy trees in a seasonally dry tropical forest (1999)

Meinzer, F. C. ; Andrade, José Luis ; Goldstein, Guillermo ; [et al.]

Springer

Oecologia 121 (1999), S. 293-301

add to mindlist on the mindlist

Details

ISSN: 1432-1939

Keywords: Key words Roots ; Sap flow ; Leaf phenology ; Stable hydrogen isotope ratio ; Panama

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Little is known about partitioning of soil water resources in species-rich, seasonally dry tropical forests. We assessed spatial and temporal patterns of soil water utilization in several canopy tree species on Barro Colorado Island, Panama, during the 1997 dry season. Stable hydrogen isotope composition (δD) of xylem and soil water, soil volumetric water content (θv), and sap flow were measured concurrently. Evaporative fractionation near the soil surface caused soil water δD to decrease from about –15‰ at 0.1 m to –50 to –55‰ at 1.2 m depth. Groundwater sampled at the sources of nearby springs during this period yielded an average δD value of –60‰. θv increased sharply and nearly linearly with depth to 0.7 m, then increased more slowly between 0.7 and 1.05 m. Based on xylem δD values, water uptake in some individual plants appeared to be restricted largely to the upper 20 cm of the soil profile where θv dropped below 20% during the dry season. In contrast, other individuals appeared to have access to water at depths greater than 1 m where θv remained above 45% throughout the dry season. The depths of water sources for trees with intermediate xylem δD values were less certain because variation in soil water δD between 20 and 70 cm was relatively small. Xylem water δD was also strongly dependent on tree size (diameter at breast height), with smaller trees appearing to preferentially tap deeper sources of soil water than larger trees. This relationship appeared to be species independent. Trees able to exploit progressively deeper sources of soil water during the dry season, as indicated by increasingly negative xylem δD values, were also able to maintain constant or even increase rates of water use. Seasonal courses of water use and soil water partitioning were associated with leaf phenology. Species with the smallest seasonal variability in leaf fall were also able to tap increasingly deep sources of soil water as the dry season progressed. Comparison of xylem, soil, and groundwater δD values thus pointed to spatial and temporal partitioning of water resources among several tropical forest canopy tree species during the dry season.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004420050931

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

8

Electronic Resource

Water relations of epiphytic and terrestrially-rooted strangler figs in a Venezuelan palm savanna (1996)

Holbrook, N. Michele ; Putz, Francis E.

Springer

Oecologia 106 (1996), S. 424-431

add to mindlist on the mindlist

Details

ISSN: 1432-1939

Keywords: Carbon isotope discrimination ; Ficus ; Hemiepiphyte ; Plant water relations ; Strangler fig

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Water use patterns of two species of strangler fig, Ficus pertusa and F. trigonata, growing in a Venezuelan palm savanna were contrasted in terms of growth phase (epiphyte and tree) and season (dry and wet). The study was motivated by the question of how C3 hemiepiphytes accommodate the marked change in rooting environment associated with a life history of epiphytic establishment followed by substantial root development in the soil. During the dry season, stomatal opening in epiphytic plants occurred only during the early morning, maximum stomatal conductances were 5 to 10-fold lower, and midday leaf water potentials were 0.5–0.8 MPa higher (less negative) than in conspecific trees. Watering epiphytes of F. pertusa during the dry season led to stomatal conductances comparable to those exhibited by conspecific trees, but midday leaf water potentials were unchanged. During the rainy season, epiphytes had lower stomatal conductances than conspecific trees, but leaf water potentials were similar between the two growth phases. There were no differences in ∂13C between the two growth phases for leaves produced in either season. Substrate water availability differed between growth phases; tree roots extended down to the permanent water table, while roots of epiphytic plants were restricted to material accumulated behind the persistent leaf bases of their host palm tree, Copernicia tectorum. Epiphytic substrate moisture contents were variable during both seasons, indicating both the availability of some moisture during the dry season and the possibility of intermittent depletion during the rainy season. Epiphytic strangler figs appear to rely on a combination of strong stomatal control, maintenance of high leaf water potentials, and perhaps some degree of stem water storage to cope with the fluctuating water regime of the epiphytic environment.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00329697

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

9

Electronic Resource

Roles of nectar robbers in reproduction of the tropical treelet Quassia amara (Simaroubaceae) (1985)

Roubik, David W. ; Holbrook, N. Michele ; Parra, German V.

Springer

Oecologia 66 (1985), S. 161-167

add to mindlist on the mindlist

Details

ISSN: 1432-1939

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Different subsets of mainland nectarivores visited Quassia amara (Simaroubaceae), a self-compatible, predominately bird-pollinated treelet, at three islands and the mainland in Panamá. Factors correlated with reproductive success, defined as seed to ovule ratio, included the species pollinating and robbing flowers, visitor activity, pollinator response to nectar robbing, and internal regulation of fruit production. The absence of robbers and former pollinators on an island separated from the mainland during the holocene was associated with shifts in flower size, nectar production, and 3–4fold increases in population reproductive success and pollinator efficiency (=seeds produced per visit). Exclusion of robbers at three sites resulted in seed production 4–12 times greater than control flowers, at which robbers accounted for 52–98% of all visits. Although 36% of buds and over 83% of all flowers were robbed, this had no direct influence on the recorded 36–61% respective abortion rates of buds and flowers. Opportunistic avian robbers appeared where normal robbers were absent; three avian robbers extensively used floral perforations made by Trigona bees, and all ancillary pollinators also robbed. Selection pressures from nectar robbers are discussed that may relate to plant reproductive fitness.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00379850

Permalink