CSV Files

Altered seasonal cycles of precipitation and temperature due to climate change have disrupted historical patterns of plant phenology – the timing of developmental stages like flowering and fruiting. Despite growing evidence that plant phenology is changing globally due to ongoing climate change, little is known about how plants in highly endangered habitats, such as vernal pools, are responding to climate variation. Furthermore, it is unclear whether the degree of habitat specialization influences a species’ phenological responses to climatic, seasonal, and microhabitat variation. To determine the susceptibility of widespread and endemic vernal pool plants to climate change in the California Central Valley, we monitored bloom onset, floral duration and termination date of two dominant vernal pool species, rosey meadowfoam (<i>Limnanthes douglasii</i><i> </i>ssp. <i>rosea</i>), a vernal pool endemic species, and whitetip clover (<i>Trifolium variegatum</i>), a vernal pool facultative species, over 7 years. We measured climate and microtopography of three vernal pools at the University of California, Merced Vernal Pool and Grassland Reserve to quantify the relationship between abiotic environmental factors and plant phenology. We found an advancing flowering schedule of 4.7 days/year for meadowfoam and 5.6 days/year for whitetip clover, respectively, with recent, rapidly changing climate. Early flowering advanced into months previously unrecorded for both species across California during the study period. Warmer and dryer environmental conditions occurring during early growth periods were strongly associated with advanced floral phenology later in the life cycle for both species. We found that the floral duration of the habitat specialist was influenced by microtopographic features of vernal pools whereas no change was observed for the habitat generalist. Finally, warmer and dryer conditions were associated with reduced occupancy rates of both focal species within vernal pools. To our knowledge, this is the first study linking current climate warming to vernal pool plant phenology and performance.