Publication Summary

To better link phenology data from time-lapse cameras and on-the-ground observations, authors of a new study in Ecosphere compared digital images of tree foliage color from spring to autumn to observations made using the USA-NPN protocols. The authors also found that chill and minimum temperature in autumn, drought stress in autumn, and heat stress in summer are all important factors to the timing of peak fall foliage color.

Mistletoes, a group of parasitic plants comprising over 1,500 species, have intricate relationships with different host species, pollinators, and seed dispersers to carry out their life cycle. The authors from a new study in Oecologia used data from the USA-NPN’s National Phenology Database from Arizona and California to look for consistencies in the leafing, flowering, and fruiting phenology between desert mistletoe and their host plants. The authors found that mistletoes are not constrained by their hosts when it comes to phenology, and use diverse strategies to maintain reproductive success.

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.

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.

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 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.

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.

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.

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.

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.