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Stable isotopes are often utilized as intrinsic tracers to study the effects of human land uses on the structural and functional characteristics of ecosystems. Here, we illustrate how stable isotopes of H, C, and O have been utilized to document changes in ecosystem structure and function using a case study from a subtropical savanna ecosystem.(More)
In southeastern Arizona, Prosopis juliflora (Swartz) DC. and Quercus emoryi Torr. are the dominant woody species at grassland/woodland boundaries. The stability of the grassland/woodland boundary in this region has been questioned, although there is no direct evidence to confirm that woodland is encroaching into grassland or vice versa. We used stable(More)
SUMMARY *The flux of carbon from tree photosynthesis through roots to ectomycorrhizal (ECM) fungi and other soil organisms is assumed to vary with season and with edaphic factors such as nitrogen availability, but these effects have not been quantified directly in the field. *To address this deficiency, we conducted high temporal-resolution tracing of (13)C(More)
The distribution of labile Cd and Zn in two contrasting soils was investigated using isotopic exchange techniques and chemical extraction procedures. A sewage sludge amended soil from Great Billings (Northampton, UK) and an unamended soil of the Countesswells Association obtained locally (Aberdeen, UK) were used. 114Cd and 67Zn isotopes were added to a(More)
The doubly labeled water (DLW) technique for measuring CO2 production (rCO2) in free-living animals requires an assessment of the elimination of both 2H and 18O from the body over a long period of time. To calculate rCO2, it is necessary to calculate water turnover (rH2O) from the 2H flux rate. In ruminant animals, the accuracy of this calculation is(More)
Carbon dioxide respired by soils comes from both autotrophic and heterotrophic respiration. 13C has proved useful in differentiating between these two sources, but requires the collection and analysis of CO2 efflux from the soil. We have developed a novel, open chamber system which allows for the accurate and precise quantification of the delta13C of(More)
In savanna parklands of southern Texas, patches of grassland and ‘discrete clusters’ of small trees and shrubs occur on sandy loam surface soils underlain by an argillic horizon (claypan) at 40 cm. Large trees and shrubs in ‘groves’ occur on deep (2 m) sandy loam soils without an argillic horizon. δ2H and δ18O of rainfall, groundwater, and soil and plant(More)
Potassium (K) and magnesium (Mg) are essential macro-nutrients, but little is known about how they are cycled within plants. Stable isotope studies have shown that the internal cycling of nitrogen (N) is independent of current nutrient supply in temperate tree species. This is ecologically significant because it allows trees to produce rapid shoot growth in(More)
The doubly labeled water (DLW) technique allows the CO2 production (rCO2) of free living animals to be estimated from the difference between the turnover of 2H2O and H218O in the body water. A fundamental assumption of this technique is that neither of the isotopes used are lost in products other than CO2 and H2O. We found, however, that 2H was lost in both(More)
Atmospheric deposition is an important input of major nutrients into forest ecosystems. The long-term goal of this work was to apply stable isotope methodology to assess atmospheric nutrient deposition in forest systems. A labelling experiment of foliage with stable isotopes of primary and secondary macro nutrients (15N, 26Mg and 42Ca injected into the stem(More)