News & Publications

Dioecy, defined as distinctly male or female individuals in a species, is uncommon in plants, occurring in only about 5% of species. Consequently, our understanding of how this group of plants is being affected by climate change is limited. A group of researchers based at Purdue University in Indiana, USA asked two questions: 1) is the synchronicity in flowering in male and female trees changing? and 2) is the timing of leaf-out and flowering changing at different rates? The researchers found that male trees are advancing their flowering time at a greater rate than female trees. This is potentially bad news for these species; this pattern could reduce pollen transfer from male to female trees and negatively impact reproductive success in these trees. The researchers also found that flowering, which occurs before leaf-out in the species evaluated in this study, is advancing more rapidly than leaf-out. This finding is good news; the increasing temporal gap between flowing and leaf-out means less interference for the transfer of pollen from male to female trees.

Future Phenology Weeks:

March 17-21, 2025

March 16-20, 2026

March 18-22, 2024 is Phenology Week - a virtual celebration of the seasonal cycles of plants and animals! The purpose of Phenology Week is to celebrate YOU, our Nature's Notebook observers, Local Phenology Programs, and partners! We'll have webinars, awards, daily challenges, observer stories, and more!

Grasslands are among the most disturbed ecosystems globally. In the areas that remain, managers must balance practices such as mowing and burning that maintain natural systems while avoiding nesting periods for grassland birds. The authors of this study used information about nest survival from scientific literature as well as climate information and the USA-NPN’s Spring Bloom Index to develop models to predict the expected nest departure timing for 36 grassland bird species. This information can provide more localized information about nesting timing to better time management actions to avoid this critical period.

Ash trees on are the decline, and the main culprit is emerald ash borer (EAB), an invasive pest that has killed millions of ash trees in the United States. Knowing where and when to expect EAB emergence gives managers an advantage in controlling this pest, helping them to know when to take actions to control the pest. In this article, Barker et al. evaluated a model that predicts activity of EAB, taking into account both phenology and locations that have suitable climate for this pest. They used observations of EAB, including those from Nature’s Notebook, to test their model and found that it correctly estimated over 99% of presence records and predicted dates of adult EAB emergence within 7 days. This paper demonstrates how your observations can be used in the realm of invasive species, helping to improve management and ultimately conserve the unique ecosystems that we care about.

Pollen alerts give allergy sufferers the potential to reduce their exposure and the negative health impacts that result. An emerging data source for alerts is observations of flowering phenology, which can be highly correlated with the presence of airborne pollen. The authors of a new study compared data from National Allergy Bureau stations on daily pollen concentrations to flowering and pollen cone data from Nature’s Notebook. They found that the strength of the relationship between open flowers and pollen cones and pollen concentration varied by the type of plant, with the best agreement for Oaks (Quercus) and walnuts (Juglans). More specific data on the timing of open flowers and pollen release, like those that you collect in Nature’s Notebook, could lead to create real-time pollen alerts with local specificity.

The ability to predict spring plant phenology has implications for ecosystem services and forest management. The amount of heat that has accumulated at a given location, called growing degree days, is one method for prediction. The authors compared phenology data collected by the Tree Spotters (a Nature’s Notebook Local Phenology Program) at an urban arboretum, to those collected in a rural forest, Harvard Forest, and found that the urban site actually required fewer GDDs than trees at the rural site, possibly due to other phenological cues such as light and a higher amount of accumulated winter chill than predicted.

A new study focuses on the creation of litter – the patterns by which trees contribute to the rich layer of decomposing material that is the foundation of the forest. A better understanding of litter creation helps fill out our understanding of the carbon cycle. With this work we are learning that your observations of fruit and leaf fall have more potential than we realized.

The authors of a new study used over 4,000 Nature’s Notebook observations of oak (Quercus) trees in the eastern US to explore the relationship between flowering and air pollen. By finding a link between temperature and open flowers, they were able to predict peak in flowering timing at pollen monitoring stations. The peak flowering timing was strongly correlated with the observed peak airborne pollen at the stations. This article is the first to explore how volunteer-collected phenology data contributed to Nature’s Notebook can be used to support better predictions of the timing and severity of allergy season.

Changing climate conditions may affect the timing of leaf-out among trees and forbs in different ways. A research team based at the University of Ottawa evaluated anticipated changes in leaf-out among these two groups of plants using data contributed to Nature’s Notebook from 965 sites across northeastern North America. The team found that understory herbs are advancing leaf-out at a greater rate than trees, especially at higher latitudes. This more rapid advancement in leaf-out could result in a longer growing season and increased carbon uptake for these plants as temperatures increase.