König P, Tautenhahn S, Cornelissen JHC, Kattage J, Bönisch G & Römermann C (2018). Advances in flowering phenology across the Northern Hemisphere are explained by functional traits. Global Ecology and Biogeography. 27:310-321. DOI: 10.1111/geb.12696
Over the past few decades, researchers are beginning to focus their efforts on the shifting phenology (i.e. the flowering of plants) due to climate change. Previous studies have shown that hotter temperatures and decreasing precipitation have been linked to plants flowering earlier in the growing season than they normally would.
You may be thinking, what’s the big deal if a plant flowers a few days earlier or later than it did the year before? It may not seem like a problem, but it could have major effects on the landscape and the organisms residing there. For example, if one plant species flowers before any other, it may have a competitive edge and dominate a landscape it wouldn’t normally maintain, changing the composition of the ecosystem. Organisms and plants are closely linked. Plants rely on organisms for pollination and spreading seeds. If plants bloom earlier than usual, pollinators may not be actively flying around plants yet. Similarly, the pollinators may be at a loss if their usual food source (the plant) is past-peak because it already bloomed.
Until now, most research has only examined one region of the world or one type of plant. Patrizia König and her colleagues sought out to expand previous research, combined with computer simulation, to gain a more comprehensive understanding of how climate change is affecting phenology across plant types globally.
How’d They Do It?
In order to understand how early flowering plants affect their environment, König and her colleagues collected data from a literature review from 18 sites across the Northern Hemisphere in North America and Europe. All the studies had to have been conducted for over 10 years in order for the researchers to have confidence in when to expect the plants to flower. In total they examined 562 plant species (including trees, shrubs, herbs and grasses) with over 600 total observations.
Within each site the authors examined historical climate data including changes in temperature and precipitation as well as traits associated with the plants such as plant height, flowering season, longevity, and growth form to assess changes in the first flowering day (FFD). If they observed a positive change in FFD this meant that the plant would bloom later in the year whereas a negative change in FFD was associated with an earlier bloom than expected for that species.
Once they collected and organized all this data the authors developed a computer simulation to assess what was impacting the changes in FFD. Was it temperature and precipitation influencing first flowering days, or was it specific to types of plants or a combination?
The authors found that from the 562 species examined, over 80% were determined to have a negative FFD. This means that the vast majority of the plants studied were developing and blooming earlier in the year. On average, current plants are flowering five days earlier compared to data from 10 years earlier!
Unlike past studies examining shifts in FFD, König and her colleagues didn’t witness temperature to be the main factor in driving these early blooms. Additionally, the authors observed that trees, herbs and grasses experiencing lower precipitation (rainfall) and moisture (daily water availability) experienced advanced FFD. Similar findings were observed for shrubs, however moisture wasn’t as big of a factor.
What’s It All Mean?
By conducting a study at such a large scale, König and her colleagues were able to confirm findings from previous small-scale studies that the environment was primarily dictating first flowering days. What’s so novel about this paper was that the researchers were able to confirm their findings on such a large scale (across the world!) and witnessed similar patterns across environments and plant types. From this König and her colleagues were able to conclude that plant traits are as important as the environmental conditions in influencing when plants first flower and that we should also consider functional traits (the characteristics that make a plant unique from other species) and interactions among plants as environmental conditions change.
Plants play a powerful role throughout the world. We build our homes with their wood, we consume them to have a well-balanced diet, we use them for medicinal purposes. They also provide habitat and food for many creatures. Information collected from this paper show that as the climate changes, so are the plants that inhabit the world. With research such as this, it should open our eyes to the effects of climate change, even slight changes, and promote protection of the world’s rich and diverse organisms.