The Source of Water Transpired by Eucalyptus camaldulensis: Soil, Groundwater, or Streams?

Thorburn, Peter J.; Walker, Glen

doi:10.1016/b978-0-08-091801-3.50042-8

Cited by 61 publications

(44 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The formation of fog and its movement onshore is therefore a thermodynamic process (advection) and diers from other atmospheric aerosol formation (e.g., cloud formation) because it does not require condensation nuclei (sea salts or atmospheric dust) to catalyze its formation, while cloud water seeding does (McIlveen 1992). Fog water and cloud water inputs can therefore be very dierent in origin, duration, chemical and isotopic composition (see Kimball et al 1988;Fuzzi et al 1996;Vermeulen et al 1997 and references therein), yet they are frequently confused as being the same thing: they are not. At my site, fog was only collected, on average, during 476% of all the fog events which occurred during the study.…”

Section: Methodsmentioning

confidence: 97%

“…Fog can also be isotopically distinguished from water in the surface soil layers that comes from convective (colder) storm systems or has been subjected to marked evaporation (Allison et al 1983;Dawson and Ehleringer 1998;. While there are a large number of factors which can in¯uence the isotopic composition of water sources that might be used by plants, if the water sources are characterized along with the isotope values of water within the xylem tissues of plants, one can determine which and how much of each water source is being used by any plant species at a particular site (White et al 1985, Dawson andEhleringer 1991;Dawson 1993a;Thorburn and Walker 1993;Brunel et al 1995;Cramer et al, in press). Therefore, for the present investigation, the stable isotope composition of fog, rainfall, shallow and deep soil water, and xylem water was determined and this information used to calculate how much of these water sources were used by plants inhabiting coastal redwood forests over a 3-year period.…”

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Fog in the California redwood forest: ecosystem inputs and use by plants

Dawson¹

1998

Oecologia

530

502

View full text Add to dashboard Cite

Fog has been viewed as an important source of moisture in many coastal ecosystems, yet its importance for the plants which inhabit these ecosystems is virtually unknown. Here, I report the results of a 3-year investigation of fog inputs and the use of fog water by plants inhabiting the heavily fog inundated coastal redwood (Sequoia sempervirens) forests of northern California. During the study period, 34%, on average, of the annual hydrologic input was from fog drip off the redwood trees themselves (interception input). When trees were absent, the average annual input from fog was only 17%, demonstrating that the trees significantly influence the magnitude of fog water input to the ecosystem. Stable hydrogen and oxygen isotope analyses of water from fog, rain, soil water, and xylem water extracted from the dominant plant species were used to characterize the water sources used by the plants. An isotopic mixing model was employed to then quantify how much fog water each plant used each month during the 3-year study. In summer, when fog was most frequent, ∼19% of the water within S.sempervirens, and ∼66% of the water within the understory plants came from fog after it had dripped from tree foliage into the soil; for S.sempervirens, this fog water input comprised 13-45% of its annual transpiration. For all plants, there was a significant reliance on fog as a water source, especially in summer when rainfall was absent. Dependence on fog as a moisture source was highest in the year when rainfall was lowest but fog inputs normal. Interestingly, during the mild El Niño year of 1993, when the ratio of rainfall to fog water input was significantly higher and fog inputs were lower, both the proportion and coefficient of variation in how much fog water was used by plants increased. An explanation for this is that while fog inputs were lower than normal in this El Niño year, they came at a time when plant demand for water was highest (summer). Therefore, proportional use of fog water by plants increased. The results presented suggest that fog, as a meteorological factor, plays an important role in the water relations of the plants and in the hydrology of the forest. These results demonstrate the importance of understanding the impacts of climatic factors and their oscillations on the biota. The results have important implications for ecologists, hydrologists, and forest managers interested in fog-inundated ecosystems and the plants which inhabit them.

show abstract

Section: Methodsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

Fog in the California redwood forest: ecosystem inputs and use by plants

Dawson¹

1998

Oecologia

530

502

View full text Add to dashboard Cite

show abstract

“…The relative importance of two distinctly different water sources has been evaluated in previous studies through implementation of a linear two-ended mixing model (Dawson and Ehleringer 1991;Flanagan et al 1992;Thorburn and Walker 1993;Brunel et al 1995;Dawson and Pate 1996). We have attempted to apply this compartmental approach for the first time to a system in which soil and underlying weathered granitic bedrock comprise the two end members.…”

Section: Introductionmentioning

confidence: 98%

Water source utilization by Pinus jeffreyi and Arctostaphylos patula on thin soils over bedrock

Kl¹,

2003

Oecologia

110

View full text Add to dashboard Cite

Stable isotopes were used to evaluate water sources for co-occurring Jeffrey pine (Pinus jeffreyi Grev & Balf.) and greenleaf manzanita (Arctostaphylos patula Greene) in the southern Sierra Nevada, California, where soils averaged only 75 cm thick but were underlain by up to 5 m of weathered granitic bedrock. Soils and underlying weathered bedrock were sampled three times during both the 1997 and 1998 growing seasons, in 25 cm increments, from 0 to 400 cm or until hard bedrock was reached, and plant stem tissue was sampled simultaneously. Extracted water from the soil/bedrock substrate and plant tissue was analyzed for delta(18)O and/or deltaD, and depth of water source was determined by inference in conjunction with moisture status of the substrate. Water source utilization over the growing seasons for both plants generally followed a pattern similar to that observed for water depletion. Predominant water use was initially from the surface soils. Progressively deeper water sources, including weathered bedrock to a depth of several meters, were exploited as the season progressed and the overlying substrate was depleted of moisture. Early in the growing season, stable isotope values were slightly lower for pine than for manzanita (e.g., average deltaD in June 1997 was -81 per thousand for pine and -77 per thousand for manzanita), and suggest that the functional rooting depth for pine may have been slightly greater than for manzanita. In September 1997, manzanita deltaD values averaged -57 per thousand while pine values averaged -85 per thousand, indicating that manzanita opportunistically utilized summer precipitation while pine used more dependable bedrock water. In 1998, soils remained moist through July due to a late snowfall. Unlike the previous year, pine and manzanita deltaD values were not significantly different in mid- and late-growing season, and both plants exploited bedrock-derived water as soil water was depleted. Water held within bedrock was essential for meeting plant transpirational requirements over the summer drought.

show abstract

“…Tree-rings are not a direct recorder of the isotopic composition of precipitation, since there are many steps along the path from source water to cellulose. In addition, the assumption that mean annual precipitation represents a correct, adequate descriptor of the water used by plants has been called into question by some studies (Dawson and Ehleringer 1991;Ehleringer et al 1991;Sternberg et al 1991;Busch et al 1992;Flanagan et al 1992; Thorburn and Walker 1993;Valentini et al 1992), because of both the biseasonal nature of precipitation in some ecosystems and differential root activities. White et al (1985) observed that pine trees from wet and dry microsites, which presumably receive similar precipitation inputs, exhibited differences in their cellulose δD values, suggesting that water stress and/or humidity differences may alter leaf water δD and thus treering cellulose δD.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen and oxygen isotope ratios of tree-ring cellulose for riparian trees grown long-term under hydroponically controlled environments

1999

View full text Add to dashboard Cite

Saplings of three riparian tree species (alder, birch and cottonwood) were grown for over 5 months in a hydroponics system that maintained the isotopic composition of source water in six treatments, ranging from -120 to +180‰δD and -15 to +10‰δO. The trees were grown in two greenhouses maintained at 25°C and at either 40 or 75% relative humidity, creating differences in transpiration rates and leaf water isotopic evaporative enrichment. The cellulose produced in the annual growth ring was linearly related to source water with differences in both slope and offset associated with greenhouse humidity. The slope of the isotopic composition of source water versus tree-ring cellulose was less than 1 for both δD and δO indicating incomplete isotopic exchange of carbohydrate substrate with xylem water during cellulose synthesis. Tests using the outer portion of the tree-ring and new roots were similar and showed that the tree-ring values were representative of the cellulose laid down under the imposed environmental conditions. The fraction of H and O in carbohydrate substrate that isotopically exchange with medium water was calculated to be 0.36 and 0.42 respectively, and biochemical mechanisms for these observed fractions are discussed. A mechanistic model of the biochemical fractionation events for both δD and δO leading to cellulose synthesis was robust over the wide range of cellulose stable isotope ratios. The experimental results indicate that both water source and humidity information are indeed recorded in tree-ring cellulose. These results help to resolve some of the disparate observations regarding the interpretation of stable isotope ratios in tree-rings found in the literature.

show abstract

The Source of Water Transpired by Eucalyptus camaldulensis: Soil, Groundwater, or Streams?

Cited by 61 publications

References 12 publications

Fog in the California redwood forest: ecosystem inputs and use by plants

Fog in the California redwood forest: ecosystem inputs and use by plants

Water source utilization by Pinus jeffreyi and Arctostaphylos patula on thin soils over bedrock

Hydrogen and oxygen isotope ratios of tree-ring cellulose for riparian trees grown long-term under hydroponically controlled environments

Contact Info

Product

Resources

About