Papers by Richard Primack
International Journal of Biometeorology
The number and diversity of phenological studies has increased rapidly in recent years. Innovativ... more The number and diversity of phenological studies has increased rapidly in recent years. Innovative experiments, field studies, citizen science projects, and analyses of newly available historical data are contributing insights that advance our understanding of ecological and evolutionary responses to the environment, particularly climate change. However, many phenological data sets have peculiarities that are not immediately obvious and can lead to mistakes in analyses and interpretation of results. This paper aims to help researchers, especially those new to the field of phenology, understand challenges and practices that are crucial for effective studies. For example, researchers may fail to account for sampling biases in phenological data, struggle to choose or design a volunteer data collection strategy that adequately fits their project’s needs, or combine data sets in inappropriate ways. We describe ten best practices for designing studies of plant and animal phenology, evalua...
Biological Conservation, 2021
The COVID-19 pandemic has disrupted the timing and substance of conservation research, management... more The COVID-19 pandemic has disrupted the timing and substance of conservation research, management, and public engagement in protected areas around the world. This disruption is evident in US national parks, which play a key role in protecting natural and cultural resources and providing outdoor experiences for the public. Collectively, US national parks protect 34 million ha, host more than 300 million visits annually, and serve as one of the world's largest informal education organizations. The pandemic has altered park conditions and operations in a variety of ways. Shifts in operational conditions related to safety issues, reduced staffing, and decreased park revenues have forced managers to make difficult trade-offs among competing priorities. Long-term research and monitoring of the health of ecosystems and wildlife populations have been interrupted. Time-sensitive management practices, such as control of invasive plants and restoration of degraded habitat, have been delayed. And public engagement has largely shifted from in-person experiences to virtual engagement through social media and other online interactions. These changes pose challenges for accomplishing important science, management, and public engagement goals, but they also create opportunities for developing more flexible monitoring programs and inclusive methods of public engagement. The COVID-19 pandemic reinforces the need for strategic science, management planning, flexible operations, and online public engagement to help managers address rapid and unpredictable challenges.
Tree Physiology, 2008
In Massachusetts, low winter temperatures delay the onset of flowering in black birch (Betula len... more In Massachusetts, low winter temperatures delay the onset of flowering in black birch (Betula lenta L.), but not in gray birch (B. populifolia Marsh.). During the winter of 2006, male inflorescences and twigs of black birch had higher water contents than those of gray birch, and the inflorescences of black birch experienced greater frost kill than those of gray birch. Vessels diameters were greater in black than in gray birch, a difference associated with a higher incidence of winter xylem embolism, as indicated by reduced xylem hydraulic conductance. In both species, recovery of hydraulic conductance in twigs that survived the winter coincided with the development of root pressure. Frost kill to male inflorescences or associated damage to plant tissues may account for the difference between species in the effect of winter temperature on the time of first flowering. In a comparison of 24 birch species, sensitivity of the first flowering date to temperature was also correlated with water content in male inflorescences.
C limate change is driving major shifts in ecosystems all over the world, including here in the U... more C limate change is driving major shifts in ecosystems all over the world, including here in the United States. Tree swallows and many other bird species are breeding earlier, forest edges are extending up the sides of mountains, and the distributions of pest insect species such as the hemlock woolly adelgid are shifting northward. Notably, most of the evidence for biological responses to climate change, including these examples, is based on studies of one or a few species. The number of examples is large, but it is difficult to know how representative they are. How is climate change affecting entire natural communities of plants and animals? Are all of the species within a community changing, or are just a few? Are most species in a location changing in the same way, or are there substantial differences among species? Are there ways to predict how species within communities might change and what the consequences of these changes will be? Despite the obvious importance of these questions, we do not really know the answers. We know many changes are happening, some of them major, but thus far our knowledge is limited to a relatively few species in a few places. To help answer the question of how plant communities are responding to climate change, we turned to one of the best-documented floras in the countrythe flora of Concord, Massachusetts. The flora has been inventoried five times since 1830, a huge effort for the flora of a single town. During two of these inventories, the botanists collected observations not only of plant occurrences, but The Impact of Climate Change on the Flora of Thoreau's Concord Abraham J. Miller-Rushing and Richard B. Primack also of flowering times. One of these two botanists was the well-known philosopher and naturalist Henry David Thoreau, and the other was a local shopkeeper, Alfred Hosmer. Between them, they recorded the flowering times of over 700 plant species in Concord. The statue of Henry David Thoreau at Walden Pond, with a replica of his cabin in the background.
PloS one, 2012
It is not known whether global warming will affect winning times in endurance events, and counter... more It is not known whether global warming will affect winning times in endurance events, and counterbalance improvements in race performances that have occurred over the past century. We examined a time series (1933-2004) from the Boston Marathon to test for an effect of warming on winning times by men and women. We found that warmer temperatures and headwinds on the day of the race slow winning times. However, 1.6°C warming in annual temperatures in Boston between 1933 and 2004 did not consistently slow winning times because of high variability in temperatures on race day. Starting times for the race changed to earlier in the day beginning in 2006, making it difficult to anticipate effects of future warming on winning times. However, our models indicate that if race starting times had not changed and average race day temperatures had warmed by 0.058°C/yr, a high-end estimate, we would have had a 95% chance of detecting a consistent slowing of winning marathon times by 2100. If average...
The Wilson Bulletin, 2004
Observations by local naturalists may provide valuable records of phenological events with which ... more Observations by local naturalists may provide valuable records of phenological events with which we can measure the response of species to climate change. To test this idea, we examined the records of a dedicated naturalist who has been observing bird arrivals, plant flowering, butterfly appearance, and frog calling on her farm in Middleborough, southeastern Massachusetts. From her 1970 to 2002 records, we extracted data on first observations of spring phenological events for 24 species-650 observations in all. Over that time, average annual local temperatures rose by 2.0Њ C. Twenty-two species showed earlier activity, with 5 of the 16 bird species now arriving significantly earlier in the year than they did 30 years ago. Twenty-two species responded to warming temperatures, with 4 species (two birds, one frog, and one plant) showing statistically significant earlier activity in years with warmer temperatures. The other 18 species showed similar trends, but they were not statistically significant.
Proceedings of the National Academy of Sciences, 2008
Climate change has led to major changes in the phenology (the timing of seasonal activities, such... more Climate change has led to major changes in the phenology (the timing of seasonal activities, such as flowering) of some species but not others. The extent to which flowering-time response to temperature is shared among closely related species might have important consequences for community-wide patterns of species loss under rapid climate change. Henry David Thoreau initiated a dataset of the Concord, Massachusetts, flora that spans ≈150 years and provides information on changes in species abundance and flowering time. When these data are analyzed in a phylogenetic context, they indicate that change in abundance is strongly correlated with flowering-time response. Species that do not respond to temperature have decreased greatly in abundance, and include among others anemones and buttercups [Ranunculaceae pro parte ( p.p. )], asters and campanulas (Asterales), bluets (Rubiaceae p.p. ), bladderworts (Lentibulariaceae), dogwoods (Cornaceae), lilies (Liliales), mints (Lamiaceae p.p. ),...
Proceedings of the National Academy of Sciences, 2009
PLoS ONE, 2010
Invasive species have tremendous detrimental ecological and economic impacts. Climate change may ... more Invasive species have tremendous detrimental ecological and economic impacts. Climate change may exacerbate species invasions across communities if non-native species are better able to respond to climate changes than native species. Recent evidence indicates that species that respond to climate change by adjusting their phenology (i.e., the timing of seasonal activities, such as flowering) have historically increased in abundance. The extent to which non-native species success is similarly linked to a favorable climate change response, however, remains untested. We analyzed a dataset initiated by the conservationist Henry David Thoreau that documents the long-term phenological response of native and non-native plant species over the last 150 years from Concord, Massachusetts (USA). Our results demonstrate that nonnative species, and invasive species in particular, have been far better able to respond to recent climate change by adjusting their flowering time. This demonstrates that climate change has likely played, and may continue to play, an important role in facilitating non-native species naturalization and invasion at the community level.
Philosophical Transactions of the Royal Society B: Biological Sciences, 2010
As a consequence of warming temperatures around the world, spring and autumn phenologies have bee... more As a consequence of warming temperatures around the world, spring and autumn phenologies have been shifting, with corresponding changes in the length of the growing season. Our understanding of the spatial and interspecific variation of these changes, however, is limited. Not all species are responding similarly, and there is significant spatial variation in responses even within species. This spatial and interspecific variation complicates efforts to predict phenological responses to ongoing climate change, but must be incorporated in order to build reliable forecasts. Here, we use a long-term dataset (1953–2005) of plant phenological events in spring (flowering and leaf out) and autumn (leaf colouring and leaf fall) throughout Japan and South Korea to build forecasts that account for these sources of variability. Specifically, we used hierarchical models to incorporate the spatial variability in phenological responses to temperature to then forecast species' overall and site-s...
Philosophical Transactions of the Royal Society B: Biological Sciences, 2010
Climate change has resulted in major changes in the phenology—i.e. the timing of seasonal activit... more Climate change has resulted in major changes in the phenology—i.e. the timing of seasonal activities, such as flowering and bird migration—of some species but not others. These differential responses have been shown to result in ecological mismatches that can have negative fitness consequences. However, the ways in which climate change has shaped changes in biodiversity within and across communities are not well understood. Here, we build on our previous results that established a link between plant species' phenological response to climate change and a phylogenetic bias in species' decline in the eastern United States. We extend a similar approach to plant and bird communities in the United States and the UK that further demonstrates that climate change has differentially impacted species based on their phylogenetic relatedness and shared phenological responses. In plants, phenological responses to climate change are often shared among closely related species (i.e. clades),...
New Phytologist, 2009
SummaryBotanical gardens have a unique set of resources that allows them to host important climat... more SummaryBotanical gardens have a unique set of resources that allows them to host important climate change research projects not easily undertaken elsewhere. These resources include controlled growing conditions, living collections with broad taxonomic representation, meticulous record‐keeping, networks spanning wide geographic areas, and knowledgeable staff. Indeed, botanical gardens have already contributed significantly to our understanding of biological responses to climate change, particularly the effects of temperature on the timing of flowering and leaf‐out. They have also made significant contributions to the understanding of the relationships among climate, physiology, and anatomy. Gardens are finding new uses for traditional research tools such as herbarium specimens and historical photographs, which are increasingly being used to obtain information on past plant behavior. Additional work on invasive species and comparative studies of responses to climatic variation are pro...
Journal of Ecology, 2008
1. First flowering dates are occurring earlier than they did in the past in many locations around... more 1. First flowering dates are occurring earlier than they did in the past in many locations around the world. It is sometimes assumed, implicitly or explicitly, that the changes in first flowering dates describe the phenological behaviour of entire populations. However, first flowering dates represent one extreme of the flowering distribution and may be susceptible to undesirable confounding effects. 2. We used observations of flowering in Colorado and Massachusetts to test whether changes in population size and sampling frequency affect observations of first flowering dates. 3. We found that the effect of population size on first flowering dates depended on location. Changes in population size were strongly related to the dates on which first flowering was observed in Massachusetts but not in Colorado. The lack of a significant effect in Colorado may reflect the rapid onset of spring after snowmelt and fixed developmental schedules of the plants at this sub-alpine site, or the scale of the plots sampled during the study. 4. We also found that changes in sampling frequency can influence observed changes in first flowering dates and other aspects of the flowering distribution. Similar to the effect of declines in population size, lower sampling frequency caused later observations of first flowering. However, lower sampling frequency, if maintained consistently throughout a study, did not significantly affect estimates of changes in flowering dates over time or in response to climate. 5. Synthesis. Researchers should consider the effects of changes in population size and sampling frequency when interpreting changes in first flowering dates. In some cases, past results may need to be reinterpreted. When possible, researchers should observe the entire flowering distribution or consider tracking peak or mean flowering dates to avoid the confounding effects of population size and sampling frequency.
Global Change Biology, 2008
Past studies of bird migration times have shown great variation in migratory responses to climate... more Past studies of bird migration times have shown great variation in migratory responses to climate change. We used 33 years of bird capture data (1970–2002) from Manomet, Massachusetts to examine variation in spring migration times for 32 species of North American passerines. We found that changes in first arrival dates – the unit of observation used in most studies of bird migration times – often differ dramatically from changes in the mean arrival date of the migration cohort as a whole. In our study, the earliest recorded springtime arrival date for each species occurred 0.20 days later each decade. In contrast, the mean arrival dates for birds of each species occurred 0.78 days earlier each decade. The difference in the two trends was largely explained by declining migration cohort sizes, a factor not examined in many previous studies. We found that changes in migration cohort or population sizes may account for a substantial amount of the variation in previously documented chang...
Frontiers in Ecology and the Environment, 2012
Ecology, 2008
As a result of climate change, many plants are now flowering measurably earlier than they did in ... more As a result of climate change, many plants are now flowering measurably earlier than they did in the past. However, some species' flowering times have changed much more than others. Data at the community level can clarify the variation in flowering responses to climate change. In order to determine how North American species' flowering times respond to climate, we analyzed a series of previously unstudied records of the dates of first flowering for over 500 plant taxa in Concord, Massachusetts, USA.
BioScience, 2012
Historical records are an important resource for understanding the biological impacts of climate ... more Historical records are an important resource for understanding the biological impacts of climate change. Such records include naturalists' journals, club and field station records, museum specimens, photographs, and scientific research. Finding records and overcoming their limitations are serious challenges to climate change research. In the present article, we describe efforts to locate data from Concord, Massachusetts, and provide a template that can be replicated in other locations. Analyses of diverse data sources, including observations made in the 1850s by Henry David Thoreau, indicate that climate change is affecting the phenology, presence, and abundance of species in Concord. Despite recent work on historical records, many sources of historical data are underutilized. Analyses of these data may provide insights into climate change impacts and techniques to manage them. Moreover, the results are useful for communicating local examples of changing climate conditions to the public.
Biological Conservation, 2009
To determine the effectiveness of conservation efforts, scientists and land managers must evaluat... more To determine the effectiveness of conservation efforts, scientists and land managers must evaluate the ability of conservation areas to protect biological diversity. The historic town of Concord, Massachusetts, home of the philosopher and naturalist Henry David Thoreau, provides a unique opportunity to examine how well conservation areas preserve biodiversity in a suburban landscape. About 35% of total land area in the town has been protected, and botanists, including Thoreau, have surveyed plants in Concord five times over the last 170 years. We spent 5 years (2003-2007) re-surveying a subset of Concord's flora for species presence and abundance. Of the species seen by Thoreau in the mid-19th century in Concord, we could not locate 27%, and an additional 36% persist in one or two populations where they are vulnerable to local extinction. Most species losses appear to have occurred in the past three to four decades. Certain groups, such as orchids, have shown particularly severe losses. More native species are declining in abundance than are increasing. Nonnative species represent an increasing percentage of the flora, with many increasing in abundance. The flora has experienced a net loss of species over the past four decades, with 82 species gained and 236 species missing. Because many species are rare on a local scale, persisting as one or two small populations, local extinctions will likely continue in coming decades. Habitat management, primarily to prevent tree establishment, appears to have allowed many rare species of open habitats to persist and recover. Active management of existing sites will likely be the key to protecting the species diversity of the Concord flora and maintaining the living connection to the writings of Thoreau.
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Papers by Richard Primack