2010 Symposium Handout
Climate Change and Plant Phenology in the Southeastern United States
by George R. Kish
U.S. Geological Survey, Tampa, Florida
Abstract: Seasonal variations in temperature and precipitation driven by weather and climate influence life cycle changes in plants. Phenology is the study of the response of living organisms to seasonal and climatic changes to their environment. Variability in phenological events, such as the beginning of the growing season, can have important environmental and socio-economic implications for health, recreation, agriculture, the management of natural resources, ecological succession, and natural hazards.
Records of phenological events (for example, first leaf date, first flower date) could reveal clues about climate change that can be used as important indicators for predicting future climate change. A new regional phenology network, the Southeast Regional Phenology Network (SERPN) has been established to integrate plant and animal phenological event observations in the southeast with national data sets and remotely-sensed weather and vegetation data.
The first phase of the SERPN focuses on plant phenology with observations of sentinel plants and naturally occurring plants in preserved or protected areas. A dogwood anthracnose resistant cultivar of flowering dogwood (Cornus florida ‘Appalachian Spring’), developed by the Tennessee Agricultural Experiment Station will be available in the spring of 2010 for use as sentinel plants for observations in the eastern United States. Although no single plant species represents the entire contiguous United States, a regional native plant list is being developed to address climate change issues important to southeastern ecosystems. A portion of the plants selected for the regional network will be to assimilate regionally unique plants into the broader nationwide network. In the Southeast, several plants selected for the regional network have overlapping range with the national network (for example, Acer rubrum, Cercis canadensis, Cornus florida, etc.). This presentation describes the plans of the Southeast Regional Phenology Network.
Definitions:
Phenology: The study of periodic plant and animal life cycle stages and how these are influenced by seasonal and interannual variations in climate. Non-biological systems also exhibit annual or period stages coupled with changes in environmental conditions (e.g., ice-in and ice-out of lakes and rivers); although this is sometimes referred to as phenology, we prefer to reserve the term phenology for biological events, and the term seasonality for non-biological events.
Phenological event: A precisely defined point in the annual life cycle of a plant or animal, generally marking the start or end point of a phenophase. The occurrence of a phenological event can be pinpointed to a single date and time (in theory, if not in practice).
Phenophase: An observable stage or phase in the annual life cycle of a plant or animal that can be defined by a start and end point. Phenophases generally have a duration of a few days or weeks. Examples include the period over which newly emerging leaves are visible, or the period over which open flowers are present on a plant.
Calibration plant species: The calibration plant species component of the USA-NPN Plant Phenology Program consists of a set of 20 plants selected to help "calibrate" phenological measurements across the USA. These native and introduced plants have broad distributions and are ecologically or economically important. The USA-NPN integrates observations on calibration species to get "the big picture" of plant responses. USA-NPN observers are encouraged to include at least one calibration species in their monitoring projects. Widespread observation of calibration species is needed so that the collective monitoring data for these plants can be integrated with climate measurements across the nation.
Implementation of the Cloned Plants Project (Excerpt from Mark Schwartz, University of Wisconsin at Milwaukee)
Our overall goal is to supply cloned plants to at least 2500 core observations sites (this number comes from an initial estimate of a 25% participation rate from the roughly 10,000 National Weather Service Cooperative [COOP] observers, a major target constituent group of the program), with approximately even spatial coverage, across the entire continental USA. Our plan places two cloned plants at every observations site, so observations can continue, even if one fails to survive. A reinvigorated and expanded lilac “network” will constitute many of these sites. However, one of the limitations of lilac observation is that the cloned varietal will not grow successfully in portions of the Southeast, Southwest, and West Coast regions of the USA. Thus, the potential for clone varietals of other species to “serve” these areas needs to be investigated. Dogwood (Cornus florida) appears well suited for the southeastern USA, since a cloned varietal resistant to the disease anthracnose is commercially available, and its idealized growth range complements and overlaps well with cloned lilac (Fig. 1). Appropriate species for the Southwest and West Coast are less certain, so more research needs to be done in order to recommend potential species for these areas.
Currently, there are approximately 430 observation sites with cloned lilacs in the continental USA. Given that full-scale efforts to recruit new observers across the entire country have not yet been employed, and many observers recruited are from other environmental observation networks (such as the National Weather Service Cooperative Program), the numbers so far are encouraging. They strongly suggest that a total future distribution of 2070 additional (2500 total) core sites nationwide is obtainable. Further, the nursery that is producing the cloned lilacs will start providing these plants direct to the public for purchase in spring 2009, which (along with partnerships with other environmental networks and education/outreach efforts) will support adding observation sites beyond the core set. Lastly, observers who monitor common lilacs and dogwood plants as part of the USA-NPN Plant Phenology Program will add to the number of stations and support the overall goals of the Cloned Plants Project, as the responses of these plants are often quite similar to their cloned “cousins”.
Plant List for Georgia – from the USA National Phenology Network (
* Indicates a calibration species
PHENOPHASES
Emerging leaves
In at least 3 locations on the plant, an emerging leaf is visible. A leaf is considered "emerging" once the green tip is visible at the end of the leaf bud, but before it has fully unfolded to expose the petiole (leaf stalk) or leaf base.
Unfolded leaves
In at least 3 locations on the plant, an unfolded leaf is visible. A leaf is considered "unfolded" when the petiole (leaf stalk) or leaf base is visible. The leaf may need to be bent backwards to see whether the petiole or leaf base is visible.
>=75% of full leaf size
For the whole plant, the majority of leaves are unfolded and have elongated to at least three-quarters (75%) of their mature size. Leaf size may also be estimated by viewing the canopy as a whole. At 75% of full leaf size, the canopy appears to be approximately three-quarters (75%) full.
>=50% of leaves colored
For the whole plant, at least half (50%) of the leaves (including any that have fallen to the ground) have changed to their late-season colors.
All leaves colored
For the whole plant, virtually all (95-100%) of the leaves (including any that have fallen to the ground) have changed to their late-season colors, and there is virtually no green left in the leaves.
>=50% of leaves fallen
For the whole plant, at least half (50%) of the leaves have fallen.
All leaves fallen
For the whole plant, virtually all (95-100%) of the leaves have fallen.
Open flowers
In at least 3 locations on the plant, an open fresh flower is visible. Flowers are considered "open" when the reproductive parts are visible between unfolded or open flower parts. Do not include spent (wilted) flowers that remain on the plant.
Full flowering
For the whole plant, at least half (50%) of the flowers are open and still fresh.
Ripe fruits
In at least 3 locations on the plant, a ripe fruit is visible.
For more information about plant phenology: www.usanpn.org (USA-National Phenology Network)
gkish@usgs.gov (for information about the Southeast Regional phenology Network)