The flowering response of Greater Philadelphia native piedmont plants to long term climate change
Date
2011
Authors
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Publisher
University of Delaware
Abstract
There is growing evidence that many plant species are flowering earlier in
recent years and that climate change is a contributing factor. These studies have
predominantly used field observations as their data source while an increasing number
of reports are utilising herbarium specimens. The current research uniquely combined
different data sources in the form of herbarium specimens, field observations and
dated photographic images to study plant species response to rising temperatures. An
analysis of 28 Greater Philadelphia species, native to Pennsylvania and Delaware
Piedmont, and 2539 flowering records from 1840 to 2010 indicated that plants are
responding to rising minimum monthly temperatures. On average, these species are
flowering 16 days earlier over this 170 year period and 2.7 days earlier per °C rise in
monthly minimum temperature. Monthly minimum temperatures one or two months
prior to flowering correlate with flowering time most significantly. Short flowering
plants and woody plants are better indicators of climate change. Phenological studies
across areas of at least 80 km in radius produce significant results. Individuals, public
gardens and institutions holding historic botanical data can play an important role in
topical research such as climate change.