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.

Linking phenology data from the past and present

Authors of a new study published in Nature Ecology & Evolution analyzed data from three sources – Henry David Thoreau’s observations recorded over 150 years ago in Massachusetts, four decades of observations collected at the Rocky Mountain Biological Laboratory, and recent observations contributed by Nature’s Notebook participants across the U.S. – to demonstrate how these disparate data sources can be combined to detect changes in flowering phenology over time.  The authors found increasing variability in the timing of flowering in recent years across datasets. This suggests that plants may be reaching the limit of how much they can advance their flowering to keep up with changing climate conditions. 

Linking bird migration with the USA-NPN’s Spring Index

The authors of this study used data from two continental-scale observation networks to explore the relationship between migratory birds and environmental cues - observations of migratory birds submitted to eBird and weather surveillance radar, which can detect large groups of migrating birds. They compared the observation data to measurements of vegetation green-up collected via satellites and the USA-NPN’s Spring Leaf Index. The Spring Leaf Index was strongly related to both the estimates of bird species richness from eBird observations and migration intensity collected via weather radar. By better understanding how birds and the habitat on which they rely are responding to climate change, managers will be more equipped to take actions to promote and conserve habitat where it is needed.

Phenology of oak trees in water-limited ecosystems tells a unique story

While many studies have investigated the relationship between climatic drivers and phenology of plants in temperate areas, few studies have explored these drivers in water-limited ecosystems.  Authors from the USA National Phenology Network and the University of California Santa Barbara used observations from Nature’s Notebook to examine how the phenology of two western North American oak species and two eastern and central North American oak species respond to variation in temperature, precipitation, latitude, longitude and elevation. The way that species respond to certain climatic drivers, such as winter precipitation or spring minimum temperatures, can be used to predict how these species will be impacted by climate change.

Extremely early springs accelerate leafing phenology

Extremely early springs such as the spring of 2012 are predicted to increase in frequency in future years, and much is still unknown about how leafing phenology will respond. Authors of a new study tracked the phenology of 43 populations of white ash and found that during the extreme year of 2012, ash leafed out an average of 21 days earlier than the non-extreme years. Changes in phenology can greatly impact a plant’s survival, as leaf-out in a seemingly early spring can put the plant at risk to damage from late-season frosts and freezes. Knowing when plants will leaf out can help farmers and gardeners to know when to plant crops and cover vulnerable early spring buds.

Phenology information can improve ecological restoration

Restoration is a vital process to return degraded, damaged, or destroyed ecosystems to a state where they can support species of interest. While plant and animal phenology information is often used to determine the impact of environmental change on plants and animals, this information has not been widely used in the context of ecological restoration.  The authors found that phenology information improved restoration projects, informing what and when to plant, improving the timing of management actions, and increasing the efficiency of post-restoration monitoring. Adding phenology information into the toolkit of restoration managers will help them to be more efficient and effective in their restoration actions.

Large herbivores track high-protein forage in spring

Finding high-quality foraging areas is crucial for hungry herbivores in the spring months. Researchers of a new study in Proceedings of the Royal Society B studied five species of herbivores in Wyoming and Utah to see whether animals matched their movements with the spring green-up of their forage across the landscape. They found that 7 of the 10 populations studied selected patches of forage in the early growth stage, supporting the hypothesis that these animals track the green wave. Learning more about how animals select habitat patches, and how much flexibility exists in their behavior, will help managers to protect these species in the face of future climate change and land development.

Spring is advancing in three of every four National Parks

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. 

Early springs and late-season freezes may become the new normal

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.

Nature’s Notebook observations help to manage invasive buffelgrass

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.

Nature’s Notebook observations validate remotely-sensed data

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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