I continue to be impressed by the quality and breadth of phenology research that this community is producing! Read below about recent studies about changes in weather extremes on public lands, the application of hierarchical survival modeling to plant phenology, and how well heat accumulation can predict activity across a season.
It's been an exciting summer for the USA-NPN team as we rolled out new products, including land surface phenology maps and an invasive plant forecast. Check these out and let us know if you have needs for additional phenology information derived from remote sensing, or, if you are working on invasive species models that could be used for decision-making by land managers.
We look forward to hearing from you as we explore and expand to exciting new areas and applications in the coming year! Warmly,
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What's new at the USA National Phenology Network
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10 year update on the NPN
In a special presentation for the USGS' public lecture series, USA-NPN founding director Jake Weltzin gave an overview of the last 10 years of the USA-NPN, highlighting how the Network has grown over the years and touching on our future directions.
Watch the recording »
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New
Nature's Notebook mobile app
We have a brand new
Nature's Notebook
mobile application to help observers record plant and animal phenology.
The new app features improved navigation, the ability to easily see and edit past observations, and an animal checklist to quickly enter animal observations. Learn about these features and more in our
mobile app tip sheet
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Documenting changes in nature
Our new
Nature's Notebook video documents how our friends at Audubon Starr Ranch in California are observing phenology and recording the changes they see around them. The video was produced by
Landmark Stories at the University of Arizona's College of Agriculture and Life Sciences.
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Invasive plant Pheno Forecast
Buffelgrass is an invasive plant that impacts native desert plant and animal communities in the Southwestern US. It creates substantial fire risk in ecosystems that are not adapted to large-scale intense burning.
This summer, the USA-NPN developed a
Pheno Forecast, our first for an invasive plant, to predict when buffelgrass reaches a level of greenness where herbicide treatment is most effective. Map users recieve weekly notifications and can let us verify if the maps are accurate by
reporting their observations.
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Land Surface Phenology maps available
The USA-NPN has released maps of land surface phenology indicators of greenness derived from MODIS Collection 6 satellite data. These maps show the timing of green-up and green-down across the continental United States across the years 2010-2017.
This suite of products can be used to ask questions such as, where has spring leaf-out occurred earlier in recent years? How variable is leaf color change is across the United States? and, Where do we see the most total greenness across the growing season?
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Changes in weather extremes on public lands
In a recent Ecological Applications article, Martinuzzi and colleagues reported on the extent to which extreme weather events are expected to change under future projection scenarios. This study, which leveraged the Spring Indices, compared projected mid-century frequency of fire weather, drought, and false springs to historical conditions within lands managed by the U.S. Forest Service.
Overall, many ranger districts, particularly in the Southwest and the Rocky Mountains, are projected to see increases in multiple weather extremes that may threaten ecosystem health and resilience.
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Hierarchical survival modeling in phenology
Elmendorf and colleagues demonstrated the value of using hierarchical survival models to predict plant phenology using USA-NPN and NEON observations.
The study, published in
Agricultural and Forest Meteorology
, found that the sensitivity to environmental drivers among species was more variable than among different regions across the United States.
Generally spring leaf-out was promoted by multiple factors including chilling, spring warming, longer day lengths, and reduced frost. Fall leaf coloration on the other hand was promoted by cold accumulation and longer day length.
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Does early spring mean early summer?
Heat accumulation in the spring is an important driver of the onset of spring phenology across many plants and animals. A recent paper by Crimmins and Crimmins in
JGR Biosciences explored the extent to which growing degree day thresholds across the growing season are correlated.
Later season thresholds were more likely to be related than those earlier in the season due to reduced variability in heat accumulation later in the season. These relationships can be used to predict whether an event associated with a particular threshold is likely to be early or late in a given year. For example, forest pest managers can use the heat accumulation status in the middle of the season to determine if insect pests will emerge earlier or later than usual and plan treatment crews accordingly.
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