Photosynthetic capacity in middle-aged larch and spruce acclimates independently to experimental warming and elevated CO.

Photosynthetic acclimation to both warming and elevated CO of boreal trees remains a key uncertainty in modelling the response of photosynthesis to future climates. We investigated the impact of increased growth temperature and elevated CO on photosynthetic capacity (V and J) in mature trees of two North American boreal conifers, tamarack and black spruce. We show that V and J at a standard temperature of 25°C did not change with warming, while V and J at their thermal optima (T) and growth temperature (T) increased.

Boreal conifers maintain carbon uptake with warming despite failure to track optimal temperatures.

Warming shifts the thermal optimum of net photosynthesis (T) to higher temperatures. However, our knowledge of this shift is mainly derived from seedlings grown in greenhouses under ambient atmospheric carbon dioxide (CO) conditions. It is unclear whether shifts in T of field-grown trees will keep pace with the temperatures predicted for the 21 century under elevated atmospheric CO concentrations.

The roles of photochemical and non-photochemical quenching in regulating photosynthesis depend on the phases of fluctuating light conditions.

The induction and relaxation of photochemistry and non-photochemical quenching (NPQ) are not instantaneous and require time to respond to fluctuating environments. There is a lack of integrated understanding on how photochemistry and NPQ influence photosynthesis in fluctuating environments. We measured the induction and relaxation of chlorophyll a fluorescence and gas exchange in poplar and cotton at varying temperatures under saturating and fluctuating lights.

Encouragement: The key to increasing the number of nurses serving on boards.

Nurses have a lot of knowledge about health and health systems but are not yet adequately represented on boards and commissions that influence health and healthcare in our country. The majority of nurses are women and the hesitancy of women to seek board and elected positions are well documented. The purpose of this statewide survey of nurses was to ascertain the political engagement of nurses and their identified barriers to service.