Plant responses to variation in moisture availability
Water availability is the primary factor limiting plant and forest productivity. Global climate models indicate an increase in temporal and spatial variation of water availability in most systems, which is expected to be realized as an increase in the frequency and severity of drought events. Over the past 15-20 years, such droughts have had major impacts on ecosystems worldwide including declines in net primary productivity and mass mortality events. Therefore, one of my primary research goals is to understand how variation in water availability influences plant- and forest function.
To accomplish this, I studied the evolution of physiological adaptions to water stress with Hafiz Maherali and Christina Caruso at the University of Guelph as part of an undergraduate thesis project. In greenhouse conditions representative of Californian Mediterranean systems in the wet (El Niño) and dry (La Niña) phases of the ENSO oscillation, we found protective plastic changes in the drought escaping grass Avena barbata that included the down regulation of photosynthesis (FvFm, Y(II), ETR) and decreased production of chlorophyll and leaf area. However, upon re-watering, these changes reduced productivity, suggesting a trade-off for plasticity in photosynthetic traits to drought.
Changes in the flowering phenology of trees is also expected to occur with increased variation in moisture availability. To explore this, I surveyed the effects of water stress on general flowering in lowland Dipterocarps (n = 50) at the Pasoh field station during the extreme El Nino last summer (2016) (as part of a field course with the Forest Research Institute of Malaysia). I found widespread early termination of flowering in drier sites, with large trees aborting flowering almost entirely. El Niño events (i.e. moisture limitation and temperature increase) are believed to initiate general flowering of Dipterocarps; however, these results show that flowering is terminated during extreme events (In prep).
To accomplish this, I studied the evolution of physiological adaptions to water stress with Hafiz Maherali and Christina Caruso at the University of Guelph as part of an undergraduate thesis project. In greenhouse conditions representative of Californian Mediterranean systems in the wet (El Niño) and dry (La Niña) phases of the ENSO oscillation, we found protective plastic changes in the drought escaping grass Avena barbata that included the down regulation of photosynthesis (FvFm, Y(II), ETR) and decreased production of chlorophyll and leaf area. However, upon re-watering, these changes reduced productivity, suggesting a trade-off for plasticity in photosynthetic traits to drought.
Changes in the flowering phenology of trees is also expected to occur with increased variation in moisture availability. To explore this, I surveyed the effects of water stress on general flowering in lowland Dipterocarps (n = 50) at the Pasoh field station during the extreme El Nino last summer (2016) (as part of a field course with the Forest Research Institute of Malaysia). I found widespread early termination of flowering in drier sites, with large trees aborting flowering almost entirely. El Niño events (i.e. moisture limitation and temperature increase) are believed to initiate general flowering of Dipterocarps; however, these results show that flowering is terminated during extreme events (In prep).
