Nature’s Notebook

Connecting People with Nature to Benefit Our Changing Planet

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You can learn more about recent phenology research in the publication summaries below.

With warmer winters, woody plants need warmer springs to come out of dormancy

For many plants, it appears that the amount of heat needed to begin leaf growth in spring is related to temperatures in the preceding winter. Under increasing temperatures in the Northern Hemisphere, many temperate woody plants may no longer be exposed to the necessary cold temperatures in winter to meet their chilling requirement, leading to delays in leaf-out.

Roots, as well as leaves, are affected by shifting temperatures

Plants rely on their roots for delivery of water and nutrients, not to mention for the structure that anchors them to the earth. Just as new leaves or needles grow in the springtime, roots also have a period of growth, or production. To better understand the relationship between leaf and root production, the authors of this study evaluated patterns in the timing of leaf and root phenology in deciduous and coniferous trees. 

Changing climate poses a greater threat to some species partnerships than others

Most scientific studies that have looked at mismatch have focused solely on relationships between plants and their pollinators. This study takes a step back, and instead of looking at the impact of mismatches, looks at the causes. The authors determine what it is about mutualistic partnerships that make them more likely to experience mismatch.

Warmer winters may delay budburst and favor pioneer and invasive species

Increasing winter temperatures could cause a delay in the onset of budburst, as well as a change in the order of when species undergo budburst. This means that in a warmer world, we could see pioneer and invasive species having an even higher advantage, which could result in decreased biodiversity and a more uniform landscape.

New models incorporating Nature’s Notebook data predict when leaves will change color in the fall

There has thus far been no clear agreement on whether autumn phenology events such as leaf color are more influenced by day length or temperature in temperate systems. The authors found that both have an influence.

Phenology helps to predict the expansion of extremely allergenic ragweed

Temperature and daylight length strongly influence the range of ragweed, an invasive weed. Ragweed can only reproduce in areas where its seeds can mature before the winter frost. This means that as the climate warms, ragweed will be able to grow in more places.  

Data from Nature’s Notebook are bringing landscape change into focus in Alaska

Spring leaf-out phenology observations have proven valuable in predicting how arctic plant communities may change in coming decades. Models used to predict changes in plant communities have traditionally taken phenology into account, but have used a single date for leaf-out averaged across all plant species. As participants in Nature’s Notebook know first-hand, the timing of leaf-out varies by species.

Deciduous trees may leaf out weeks earlier under future warming

Warming temperatures are prompting many trees in temperate regions to put on leaves in the spring earlier than they have in the past. Climate change models predict continued warming of up to several degrees C by 2100. A team of researchers at Princeton University, led by David Medvigy, developed a nuanced model to predict the timing of leaf-out in the future. 

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