Effects of Branch Warming on Tall, Mature Oak Trees
Nakamura, M., Muller, O., Tayanagi, S., Nakaji, T. and Hiura, T. 2010. Experimental branch warming alters tall tree leaf phenology and acorn production. Agricultural and Forest Meteorology 150: 1026-1029.
The five researchers report that time of leaf flush in the spring was unaffected by warming; but they found that the growing season of canopy leaves was extended by later leaf fall, which on warmed branches occurred about 10 days later than it did on control branches. And, perhaps most impressive of all, they discovered that "when acorns were present, warmed branches had about double the number of acorns found on control branches."
In the final sentence of the abstract of their paper, Nakamura et al. write that the "application of this technique should lead to a better understanding of how tall, mature trees respond to global warming." And we have to agree with them, as they state in the final paragraph of their paper, that these "changes in the phenologies of canopy leaves and acorn production will play major roles in forest ecosystem processes," which roles would appear to be both very positive and very important.