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A new study by researchers at the USA-National Phenology Network, US Geological Survey, University of Arizona, Schoodic Institute, Cornell University and the University of Wisconsin-Milwaukee shows that climate change is already happening on public lands. The authors found that spring is advancing in 76% of the 276 Parks studied, and 53% of parks are experiencing extreme early springs that exceed 95% of historical conditions. Better knowledge of warming trends will help Parks to treat invasive species, operate visitor facilities, and schedule popular climate-related events, such as flower festivals and fall leaf-viewing. |
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The “false spring” of 2012 was the earliest in an over 100 year record, and resulted in large-scale agricultural losses. To find out if these types of springs will become more common in the future, researchers used new climate change simulation models, including the USA-NPN’s Spring Indices, to distinguish natural climate fluctuations from longer-term trends. They found that by mid-century, we could see springs like that of 2012 as often as one out of every three years. They also found last freeze dates may not change at the same rate, resulting in more large-scale tissue damage and agricultural losses. |
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Buffelgrass, an invasive perennial grass that responds well to fire and outcompetes natives, threatens to transform the current Sonoran desert landscape. Managers need to treat buffelgrass with herbicides when the plant is at least 50% green. The authors of a new study in the journal Remote Sensing found that buffelgrass responds quickly to rain, with plant green up occurring twice as fast in areas with buffelgrass than areas with mostly native vegetation. This information will help managers know when to get out to spray buffelgrass. Studies such as this, which integrate on-the-ground observations of phenology with satellite data, demonstrate the power of multiple data sources to inform management activities. |
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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. |
