D4.3.10 Disruption to the synchrony of phenological events by climate change (HL) Notes

Disruption to the Synchrony of Phenological Events by Climate Change

1. Phenological synchrony refers to the timing of biological events (such as flowering, breeding, or migration) within an ecosystem, where different species' life cycles are typically coordinated.
2. For example, the timing of spring growth in plants often aligns with the arrival of migratory animals that rely on these plants for food.
3. Climate change, however, is disrupting this synchrony, with consequences for species interactions and ecosystems as a whole.

Why Does Synchrony Matter?

1. Many species rely on cues like temperature or photoperiod (day length) to time their life events.
2. When these cues fall out of sync, it can lead to mismatches between species that depend on each other.

Key Factors Disrupting Synchrony

1. Temperature: For some species, temperature is the key cue that triggers biological events. Warmer temperatures are advancing the timing of seasonal events such as growth in plants and breeding in animals.
2. Photoperiod: For other species, the length of daylight (photoperiod) is the critical factor. This is particularly evident in species that use the seasonal change in day length to regulate timing, such as migrating birds or deciduous trees that rely on changing light to mark the onset of spring.

Arctic Mouse-ear Chickweed (Cerastium arcticum) and Migrating Reindeer (Rangifer tarandus)

1. In the Arctic, the spring growth of the Arctic mouse-ear chickweed and the arrival of migrating reindeer are two critical biological events that have traditionally been synchronized.
2. However, climate change is causing shifts in both events, creating a mismatch.

Arctic Mouse-ear Chickweed

1. This small herbaceous plant grows in the Arctic tundra, and its spring growth is primarily influenced by temperature.
2. As temperatures rise, the plant begins to bloom earlier in the season.
3. However, this earlier bloom could create issues for other species that rely on it for food.

Migrating Reindeer

1. Reindeer typically migrate seasonally, timed to match the availability of fresh vegetation in the spring.
2. They rely on the availability of spring growth like that of chickweed as an essential food source.
3. If the chickweed blooms earlier than usual due to rising temperatures, the reindeer may arrive too late to take advantage of it, leading to food shortages and potentially affecting their reproductive success.