Ecological responses to climate change Phenological mismatch and leading/trailing edge dynamics

Climate & phenology: Phenological mismatch

The study of recurring life cycle stages What is phenology? Spring wildflowers Bird migration Let’s start by defining the term phenology. We all have an intuitive sense of phenology (e.g., autumn migrations, leaf change, ripening fruits in your garden, bugs splattering on the windshield in spring). Can you think of signs of the seasons from your home community? Phenology is the scientific quantification of these events. Foliage color change Mushrooms flushing Cold & flu season The study of recurring life cycle stages 3

Phenology is a key biological indicator Plants & animals are dynamic over the seasons Vegetative phenology Reproductive phenology In addition to economic important, phenology is biologically important Dynamic plants and animals– the phenological status of an individual plant is very different in March, August, and December… We can think about this dynamic nature is two bins, focusing on vegetative and reproductive there are different implications for shifting vegetative and reproductive plant phenology.

Phenology is a key biological indicator Plants & animals are dynamic over the seasons Reproductive phenology Non-reproductive phenology In addition to economic important, phenology is biologically important Dynamic plants and animals– the phenological status of an individual plant is very different in March, August, and December… We can think about this dynamic nature is two bins, focusing on vegetative and reproductive there are different implications for shifting vegetative and reproductive plant phenology.

Phenology is a key ecological indicator Ecological interactions Plants & animals are dynamic over the seasons Ecological interactions In addition to economic important, phenology is biologically important Dynamic plants and animals– the phenological status of an individual plant is very different in March, August, and December… We can think about this dynamic nature is two bins, focusing on vegetative and reproductive there are different implications for shifting vegetative and reproductive plant phenology.

Phenological responses to climate change Many organisms are already seen to be advancing their phenology in response to the warming climate The magnitude of phenological change varies between species and ecological groups Advance can be greater or less Some show little change or in some cases even delayed phenology Phenological mismatch occurs when the response differs between interacting species, disrupting their ecology Parmesan 2007 Global Change Biol. 7

Phenological mismatch can cause population crashes One example of asynchrony, or a phenological mismatch, was documented in a 2006 paper by Both et al. The study looked at the population ecology of the long-distance migratory passerine, the pied flycatcher; the authors had previously found that the flycatchers have advanced their laying date but not the timing of their spring arrival in the Netherlands. The temperate forest habitat in the study area is characterized by a clear peak in caterpillar abundance in the spring, and the caterpillars are an important food source for the birds. The authors have previously shown that the peak date is caterpillar emergence has shifted forward over the past 20 years In this study, they found that in study areas where the peak date in caterpillar emergence has shifted the most, bird populations have the strongest negative trend (i.e., declining bird populations). The flycatchers are long-distance migrants with a relatively fixed spring migration program; when moths emerge earlier, there is a shorter period between the arrival of the migrating birds and the time of peak food As documented in the Parmesan study, phenological responses to climate change may differ across trophic levels/functional groups; this may result in mismatches, such as birds failing to breed at the time of maximal food abundance. Leafing out earlier Do unchecked caterpillar populations also have a negative effect on oaks? Emerging earlier English oak Winter moth Pied flycatcher The birds’ arrival and breeding events are now mistimed compared to the peak availability of food for nestlings. Bird populations have declined by as much 90% where this mismatch occurs. Migrating at the same time each year Both et al. 2006 Nature 8

Wildflower phenology at Pepperwood Preserve

Climate & demography: Leading/trailing edges

Suitability models to predict future habitat California blue oak Oregon white oak Even though there's a lot of uncertainty in this kind of modeling, we can look for common patterns and detect the emerging trends in the field. These maps are based on just one climate model and one time period, [HadGEM2, RCP6.0, 2070-2099], but what can they tell us more generally?

Demographic leading and trailing edges The leading edge: Adults survive longer Reproduction is higher Juveniles establish more commonly Pictured: blue oaks in Lake County The trailing edge: More adult mortality Lower reproduction Fewer juveniles Pictured: blue oaks in Fresno County

Long-term forest monitoring plots Fifty 20m x 20m plots and seventeen 100m x 100m plots established in 2013 and 2015 Over 7000 tagged trees and thousands of seedling counts Additional co-located climate and hydrology research