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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.

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.

Researchers from North Carolina State University and the University of Montana found weekly survival decreases of up to 7% for hares that had coat color that was mismatched with their surroundings, making them stand out like lightbulbs on a dark background. The researchers used models to predict how the population of hares is likely to change given the survival rates they observed. Under future climate change scenarios, they project that hare populations could decrease by up to 23% by the end of the century.

Flowering in sub-tropical regions is thought to be more sensitive to temperature than precipitation, though this has not been widely studied. The authors of this study looked at herbarium records of over 1700 native herbaceous flowering plant species from South Carolina from 1951 to 2009. They found plants with early spring, late spring, and summer flowering were all responsive to increasing February and March temperatures.

Animals may be adversely affected if they are not able to match shifts in timing of their food or other resources. The authors of a new study found black-throated blue warblers have a varied diet and ability to shift the timing of their nesting, which allows them to be less susceptible to trophic mismatch after arrival at their breeding grounds.

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.

An international team of scientists found that Barnacle Geese overtake the green wave, first arriving at the southernmost stopover sites along their migration pathway to fatten up on the peak plant biomass, then arriving at their northern breeding grounds at the local start of spring. This allows growing goslings the highest amount of nutrients and thus the best chance at survival.

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.

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.

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.