Desiccation tolerance
Bryophytes possess a remarkable ability to equilibrate their cellular water levels with atmospheric water levels (humidity), a trait known as poikilohydry. Wetting and drying cycles often take place so quickly that it is difficult to imagine the complexity involved. As bryophytes sense an increase or decrease in ambient water levels they coordinate a suite morphological and physiological changes that help the bryophyte grow and survive. Much research has been done to understand and describe the principal stages involved in drying and rewetting that drive these changes (see review by Stark 2017 in the Bryologist for more information). Mandy collaborated with the Desiccation and Diversity in Dryland Mosses project, supported through the National Science Foundation’s Dimensions in Biodiversity Program, to better understand this complexity. Our research is focused on the physiological challenge of rehydration.
Bryophyte functional traits
One way that bryophytes adapt to different environments is by varying functional traits at the leaf and cell level to improve water retention and uptake (or sometimes inhibit water uptake until conditions are right) and expedite their ability to maintain a positive carbon balance. We are exploring bryophyte functional trait differences at inter and intraspecific levels. This work is being done with Kirsten Fisher (Cal State LA), Kirsten Coe (Middlebury), Daniel Stanton (U Minnesota), and John Brinda (MOBOT).
Rehydration
During the transition from dried to rehydrated, the cellular integrity of bryophytes is compromised and large amounts of intra-cellular contents (carbohydrates, amino acids, and ionic compounds) are lost. Our recent research suggests that these compounds, previously thought to be reabsorbed by bryophytes, can be washed through bryophyte canopies and into soil as throughfall. We found differences across species in the amount of carbon and nitrogen lost during rehydration and the effects of these compounds on soil biogeochemical cycling.
Ecological implications of bryophyte rehydration
Bryophyte are prevalent in ecosystems worldwide where they co-occur with vascular plants yet there have been no studies of the effects of bryophyte rehydration on growth or interactions of plants or soil biota. If the physiological response of bryophytes to rehydration yields labile resource pulses, these pulses could significantly influence biotic interactions (see research on interactions between mosses and Centaurea stoebe), community structure and nutrient cycling. We are exploring the ecological effects of bryophyte rehydration by adding bryophyte rehydration leachates (“bryo-tic pulses”) to plants and soils in laboratory and greenhouse experiments. This work is being done in collaboration with: Ben Sullivan (UNR), Morgan Luce McLeod (MPG Ranch), Ylva Lekberg (MPG Ranch), and Ray Callaway (UM).