Optimality theory states that whole-tree carbon gain is maximized when leaf N and photosynthetic capacity profiles are distributed along vertical light gradients such that the marginal gain of nitrogen investment is identical among leaves. However, observed photosynthetic N gradients in trees do not follow this prediction, and the causes for […]
The results of a 3-yr study on the effects of elevated CO2 on soil N and P, soil pCO2, and calculated CO2 efflux in a fire-regenerated Florida scrub oak ecosystem are summarized. We hypothesized that elevated CO2 would cause (i) increases in soil pCO2 and soil respiration and (ii) reduced […]
Elevated carbon dioxide (CO2) caused greater accumulation of carbon (C) and nutrients in both vegetation and O horizons over a 5-yr sampling period in a scrub oak ecosystem in Florida. Elevated CO2 had no effect on any measured soil property except extractable phosphorus (P), which was lower with elevated CO2 […]
Isoprenoidal glycerol dialkyl glycerol tetra ethers (iGDGTs) are core membrane lipids of many archaea that enhance the integrity of cytoplasmic membranes in extreme environments. We examined the iGDGT profiles and corresponding aqueous geochemistry in 40 hot spring sediment and microbial mat samples from the U.S. Great Basin with temperatures ranging […]
Structural and physiological changes that occur as trees grow taller are associated with increased hydraulic constraints on leaf gas exchange, yet it is unclear if leaf-level constraints influence whole-tree growth as trees approach their maximum size. We examined variation in leaf physiology, leaf area to sapwood area ratio (L/S), and […]