Miller-Rushing, A. J. and R. B. Primack. Global warming and flowering times in Thoreau's Concord: A community perspective. Ecology

Department of Biology, Boston University, Boston, Massachusetts 02215, USA.
Ecology (Impact Factor: 4.66). 03/2008; 89(2):332-41. DOI: 10.1890/07-0068.1
Source: PubMed

ABSTRACT 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. These records began with six years of observations by the famous naturalist Henry David Thoreau from 1852 to 1858, continued with 16 years of observations by the botanist Alfred Hosmer in 1878 and 1888-1902, and concluded with our own observations in 2004, 2005, and 2006. From 1852 through 2006, Concord warmed by 2.4 degrees C due to global climate change and urbanization. Using a subset of 43 common species, we determined that plants are now flowering seven days earlier on average than they did in Thoreau's times. Plant flowering times were most correlated with mean temperatures in the one or two months just before flowering and were also correlated with January temperatures. Summer-flowering species showed more interannual variation in flowering time than did spring-flowering species, but the flowering times of spring-flowering species correlated more strongly to mean monthly temperatures. In many cases, such as within the genera Betula and Solidago, closely related, co-occurring species responded to climate very differently from one another. The differences in flowering responses to warming could affect relationships in plant communities as warming continues. Common St. John's wort (Hypericum perforatum) and highbush blueberry (Vaccinium corymbosum) are particularly responsive to changes in climate, are common across much of the United States, and could serve as indicators of biological responses to climate change. We discuss the need for researchers to be aware, when using data sets involving multiple observers, of how varying methodologies, sample sizes, and sampling intensities affect the results. Finally, we emphasize the importance of using historical observations, like those of Thoreau and Hosmer, as sources of long-term data and to increase public awareness of biological responses to climate change.

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    • "Ecological changes in the distribution and phenology (seasonal timing of reproduction and other life history events) of plants and animals have been found for marine, freshwater and terrestrial species (Parmesan 2006). Analyses of long term datasets have shown an advance in flowering time for plant species in Europe (Fitter and Fitter 2002, Penuelas et al. 2002, Menzel et al. 2006), North America (Primack et al. 2004, Miller-Rushing and Primack 2008) and Japan (Miller-Rushing et al. 2007). Advances in the timing of phenological events have also been found in butterflies (Roy and Sparks 2000, Forister and Shapiro 2003, Stefanescu et al. 2003), birds (Both et al. 2004), amphibians (Beebee 1995) and mammals (Inouye et al. 2000). "
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    • "In temperate climates, a pattern reported worldwide is for flowering onset to shift earlier in concert with warmer springtime temperatures (Fitter and Fitter 2002, Miller-Rushing and Primack 2008, Chambers et al. 2013). The magnitude and even the direction of shifts in flowering time can, however, vary among species in the same community (Bradley et al. 1999, Miller-Rushing and Primack 2008, CaraDonna et al. 2014) and along elevational gradients (Crimmins et al. 2010). There is some evidence that the phenologies of pollinating insects are shifting with climate change, as well (Roy and Sparks 2000, Gordo and Sanz 2006, Doi et al. 2008, Burkle et al. 2013). "
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    ABSTRACT: Climate change-induced shifts in flowering phenology can expose plants to novel biotic and abiotic environments, potentially leading to decreased temporal overlap with pollinators and exposure to conditions that negatively affect fruit and seed set. We explored the relationship between flowering phenology and reproductive output in the common shrub pointleaf manzanita (Arctostaphylos pungens) in a lower montane habitat in southeastern Arizona, USA. Contrary to the pattern of progressively earlier flowering observed in many species, long-term records show that A. pungens flowering onset is shifting later and the flowering season is being compressed. This species can thus provide unusual insight into the effects of altered phenology. To determine the consequences of among- and within-plant variation in flowering time, we documented individual flowering schedules and followed the fates of flowers on over 50 plants throughout two seasons (2012 and 2013). We also measured visitation rates by potential pollinators in 2012, as well as both fruit mass and seeds per fruit of flowers produced at different times. Fruit set was positively related to visitation rate but declined with later dates of flower production in both years. Total fruit production per plant was positively influenced by flowering duration, which declined with later flowering onset, as did fruit mass. Individual flowering schedules were consistent between years, suggesting that plants that begin flowering late have lower reproductive output each year. These patterns suggest that if pointleaf manzanita flowering continues to shift later, its flowering season may continue to become shorter, compressing floral resource availability for pollinators and leading to reduced reproductive output. These results reveal the negative effects of delayed phenology on reproductive output in a long-lived plant. They highlight the value of using natural variation in flowering time, in combination with long-term data, to anticipate the consequences of phenological shifts.This article is protected by copyright. All rights reserved.
    Oikos 08/2015; DOI:10.1111/oik.02573 · 3.44 Impact Factor
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    • "four flowering seasons were classified according the climatic conditions in the research area as follows: March to May as spring season, June to August as summer season, September to November as autumn season and December to the coming February as winter season) were used as an alternative ; for each flowering month without a definite date, the median of a month (i.e. 15th) was regarded as an alternative flowering date, hoping to decrease possible bias resulting from different population sizes and sampling efforts and limit uncertainty regarding impacts of flowering duration by sampling at a specific area (Calinger et al. 2013; Miller-Rushing and Primack 2008). The midpoint is a conservative and reasonably robust estimate of median flowering time (Kochmer and Handel 1986). "
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    ABSTRACT: Aims Exploring flowering patterns and detecting processes are essential when probing into the nature of reproductive traits during the life history and the interactions among different evolutionary clades. Such patterns are believed to be influenced by many factors, but quantifying these impacts at the community-level remains poorly understood.
    Journal of Plant Ecology 04/2015; 8(2):187-196. DOI:10.1093/jpe/rtv009 · 2.65 Impact Factor
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