Rising Night-Time Temperatures: Boon or Bane of Pioneer Tropical Trees?
Cheesman, A.W. and Winter, K. 2013. Elevated night-time temperatures increase growth in seedlings of two tropical pioneer tree species. New Phytologist 197: 1185-1192.
After collecting seeds of two fast-growing tropical pioneer tree species - Ficus insipida and Ochroma pyramidale - from forests surrounding Panama City, Cheesman and Winter grew the seedlings the seeds produced in controlled-environment chambers at a constant daytime temperature (33°C) and a range of increasing night-time temperatures (22, 25, 28 and 31°C) for 38 days in the case of O. pyramidale and for 54 days in the case of F. insipida, after which they harvested the young trees and determined their total biomass production.
The results of their analysis showed that in going from the coldest to the warmest night-time temperature treatment, total tree biomass accumulation rose from a mean of 0.85 g per seedling to a mean of 2.23 g per seedling in F. insipida; while in O. pyramidale, corresponding biomass accumulation values were 1.21 g and 2.65 g. And these enhancements in growth rates in response to rising night-time temperatures even occurred in spite of warming-induced increases in leaf-level dark respiration rates! Given such findings the two researchers state that "contrary to the notion of adverse effects of increasing night-time temperatures on tropical tree performance (Clark et al., 2003, 2010), our results demonstrate that under well-watered conditions elevated night-time temperature promotes growth in seedlings of two neotropical pioneer tree species ... even at 31°C, far in excess of night-time temperatures currently seen in lowland Panama."
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