Sensitivity of tropical pendant bryophytes: results from a translocation experiment along an elevation gradient

We studied growth of three epiphytic bryophyte species in Kenya to determine their sensitivity to environmental changes. Bryophytes collected from a cool and moist upper montane forest were used to prepare 180 pendant transplants. Sixty transplants were placed in their natural habitat while 120 were transferred to two warmer and drier sites in a lower montane forest. After one year, all the transplants recovered from the lower montane forest were transferred back to the upper montane forest. In the third year, half of the remaining transplants were left in their location, and half transferred to an eucalyptus plantation forest, both in the upper montane zone. After each year subsamples were taken from each group for growth measurements. The epiphytic bryophytes demonstrated considerable resilience during the experiment. They clearly suffered from the warm and dry conditions of the lower montane forest, but quickly recovered and then exhibited growth rates comparable to those of the controls. In the third year there was no statistical difference in the growth of transplants in their natural location and in the eucalyptus plantation. This indicates that the lack of suitable substrate is the primary factor limiting bryophyte biomass in plantation forests rather than unsuitable microclimate per se.