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While there is great potential in linking data collected by observers on the ground and data collected by remote satellites, few studies have successfully combined these two types of data. Researchers from the Appalachian Laboratory at the University of Maryland Center for Environmental Science compared observations of leaf phenology collected through the Nature’s Notebook PopClock campaign to continental-scale satellite imagery collected by the Moderate Resolution Imaging Spectrometer (MODIS). They implemented three quality control procedures that resulted in a high correlation between the two datasets (r2 = 0.67). Being able to more easily combine citizen science and remotely-sensed data will give scientists a large amount of information over a range of geographic scales, to better understand the response of forest plants to future changes in climate. |
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A group of researchers based at Yale University aimed to clarify regional long-term trends in the growing season for the U.S. by combining these ground-based observations with the oft-used satellite derived information. Over the past 30 years, the growing season has lengthened by approximately one week in the eastern U.S. and the upper Rocky Mountains, and that these changes are a direct result of warming temperatures in these regions. |
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Researchers from Princeton, Chapman University, and UCLA developed models of valley oak leaf-out under past and future climate scenarios to test how changing the spatial scale of these models affects leaf-out. The authors used data collected by the California Phenology Project, which began in 2010 and is part of the USA National Phenology Network, to validate their models of valley oak leaf-out before downscaling the models to create local predictions of leaf-out. |
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The earlier springs seen in recent decades may become a permanent change. Researchers at UW - Madison predict that by the end of this century, spring will appear approximately three weeks earlier across the continental U.S. False springs are also likely to increase in the Great Plains and portions of the Midwest. |
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Researchers from the California Phenology Project compared observations of leaf budburst, flowering, fruiting and leaf drop with climate variables such as temperature and rainfall. The authors found that in all four species, at least one phenophase responded to higher winter low temperatures with delayed onset. Generally, precipitation strongly influenced leaf phenology, while both precipitation and temperature were important for flower and fruit phenology. |
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Using data from phenology observation programs, including Nature’s Notebook, the authors found that leaf unfolding is triggered more by daytime temperatures than by nighttime temperatures. This knowledge can lead to better predictions of when leaf-out might occur and improve vegetation models to estimate how phenology will change over different parts of the globe. |
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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. |
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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. |
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Learn what your 2014 observations reveal, and the ways scientists are using your observations. We cover results from the 2014 Campaigns, as well as a range of other results from observers across the country. |
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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. |
