What was done
The author measured photosynthetic rates of eastern hemlock (Tsuga canadensis L.) growing within a 200-year-old forest in Massachusetts, USA, in order to develop an ecosystem carbon exchange model for this coniferous evergreen forest.  The present paper concentrates primarily on low-temperature photosynthetic rates measured in eastern hemlock during the autumn and winter months of three successive years.

What was learned
Midday rates of photosynthesis were limited by subfreezing air temperatures that occurred during the previous one to two nights.

What it means
If autumn and winter air temperatures were to increase, even slightly, photosynthetic rates of eastern hemlock forests during the colder half of the year should increase too.  In addition, the increased carbohydrate storage that would occur during this period would be expected to subsequently enhance new foliage and wood production the following spring.  The likely net result of this chain of events would thus be significantly enhanced annual carbon storage.