Implications of global warming
The flowering patterns shown for C. pallens appear to be very sensitive to the sequence and level of January temperatures. This has strong implications for global warming. McKone et al. (1998) worked on Chionochloa species at Takahe Valley in southern New Zealand and showed similarly sharp cut offs between warm years and high flowering efforts. They considered that if mean air temperatures increased by 1-2 degrees C, as predicted under recent global-circulation models, the frequency of flowering would increase, and this could result in a breakdown of synchrony to decrease the CVp (the variation in population-level reproduction). If flowering variability decreased, predator satiation would become much less effective, and the plants would have fewer surviving seeds just at the time that they need to migrate attitudinally to cope with climate shifts. The models in Rees et al. (2002) support the conclusions of McKone et al. (1998). The effect of increasing mean temperatures, at least in the short term, would be to increase the fraction of years when flowering is possible. This will decrease CVi (the variation among years by each individual plant, the CV for each plant), since each plant will have less time between flowering efforts to accumulate reserves, and hence will decrease CVp, and increase seed predation.
This problem could be relevant to a wide range of species, if the underlying resource models used here apply, because many masting species have been shown to respond to temperature cues and to suffer higher seed predation at lower CVs.
The effect of last years January temperatures on the flowering intensity of Chionochloa pallens, a 1 degree C increase in January temperatures results in a 10 fold increase in flowering for Chionochloa.
Relationship between the mean temperature of the previous January and the flowering intensity displayed that year, in the form of inflorescences per tussock