δ¹³C and δ¹⁸O trends across overstory environments in whole foliage and cellulose of three Pinus species

Abstract

where a 18 0 1w is the oxygen isotope ratio of leaf water, a 18 0 sw is the oxygen isotope ratio of source water, s" is the fractionation that occurs during the change from liquid water to vapor, ek is the kinetic fractionation that occurs as water diffuses across the stomata and the leafs boundary layer, a 18 0 v is the oxygen isotope ratio of atmospheric water vapor, e a is the atmospheric water vapor pressure, and e i is the water vapor pressure in the leaf [7,10]. In well-mixed conditions, the enrichment of atmospheric water vapor above source water

Leaf δ18O of remaining trees is affected by thinning intensity in a semiarid pine forest

“…McDowell et al (2003) reported depletion of d 13 C values in Pinus ponderosa after forest thinning, due to a greater increase in gs than in A that led to reduced WUEi in remaining trees. By contrast, Warren et al (2001) and Powers, Pregitzer & Palik (2008) reported foliar d 13 C enrichment in various Pinus species after thinning, which they attributed to differential enhancement of A over gs due to increased foliar nutrient concentrations and greater canopy light interception in remaining trees. Other studies have reported no change in the d 13 C values of remaining pine trees after thinning Sala et al 2005;McDowell et al 2006), allegedly due to roughly parallel increases in both gs and A, without significant change in WUEi.…”

“…Huang et al (2008) and Brooks & Coulombe (2009) recently used this dual isotope approach to investigate the effects of various forest management practices (weed control, fertilizer addition) on tree physiological status. However, to the best of our knowledge, only Powers et al (2008) have used both foliar d 18 O and d 13 C to evaluate the effects of silvicultural thinning on the performance of remaining trees. Powers et al (2008) found increased d 13 C and no significant change in d 18 O in response to thinning, which they interpreted as evidence of enhanced A (and to a lesser extent, gs) in remaining pine trees.…”

“…Barbour et al 2000;Sullivan & Welker 2007;Powers et al 2008; although cellulose extraction may be necessary when comparing plants grown under different environmental conditions, as in Grams et al 2007).…”

Water relations of pine seedlings in contrasting overstory environments

“…Oxygen isotope ratios were measured at the Washington State University Stable Isotope Core Laboratory using a pyrolysis elemental analyzer (TC/EA, ThermoFinnigan, Bremen) connected to a continuous flow isotope ratio mass spectrometer (Delta PlusXP, Thermofinnigan, Bremen). Whole foliar tissue was used rather than cellulose because a previous study found whole foliage and cellulose provided similar environmental signals in the three species considered here (Powers et al, 2008a).…”

Larger investment in roots in southern range-edge populations of Scots pine is associated with increased growth and seedling resistance to extreme drought in response to simulated climate change

“…Analyses were performed on whole-leaf tissue rather than extracted cellulose since both are strongly correlated (West et al, 2001;Sullivan and Welker, 2007;Powers et al 2008). The isotopic ratio was expressed in delta notation (δ 13 C, δ 15 N) in per mil (‰) as relative deviation from the international standard V-PDB.…”