Rural System's

Rural Timing

The Phenology Group

Rural Timing is a group affiliated with Nature Folks and others. It concentrates on phenology, the study of the timing of biological event occurrences, the change in these events over the years (e.g., the migration of geese, the fall of leaves, the blooming of daffodils), and their correlations throughout Virginia and the region. White et al. (1997) said it was " the study of recurring vegetation cycles and their connection to climate." Taylor (1969) said it was the observation of life cycle phases of plants and animals in their environment throughout the year.

Rural Timing is an organization (similar to those in Europe) of nature observers who are interested in the timing of biological events. Kochmer and Handel (1986) said that for almost 100 years, plant ecologists have tried to explain the seasonal timing of flowering in animal pollinated plants.

With the internet observers may be able to report and follow the progression of seasons up and down the Atlantic coast as refelected in 5 - 10 "standard" observations, work on altitude differences (Scott Klopfer has done some of this work), and enjoy the companship of people with similar interests, do local research, support regional studies, have conferences, coordinate among countries, promote or sponsor tours that "follow the flowers" or" follow the geese", and take pleasure in unusual findings. A salary can be supported herein, especially for a role within other aspects of Rural System. Regular contacts with local TV station climate interest may be productive.

Whether "spring is early this year" is interesting or not in street conversations, it is likely to be based on observations of birds or the flowering or emergence of plants. It may be come important to understand these events and their stimuli or associates as risks of significant climate change occur (i.e., global warming.)

Understanding the timing of biological events and being able to predict them can lead to improved models and new understanding of pest emergence, planting and harvest dates, waterfowl migration, the break of hibernation periods for amphibians and mammals. In related wild faunal work, between-year comparisons of grouse population density may relate to breeding and nesting indicated by the timing of events such as grouse drumming. For years, using phenological time and not chronological time for making comparisons has been recommended. About 1969 an appeal was made through the International Biological Program for scientists to orient their studies to phenology to provide a unified effort to better understand biological phenomena, those beyond the growing season as for most crop and grassland plants.
Seasonal Progressions

  • Species A________________
  • Species B         ________

The start and extent of the flowering period for garden plant and agrden design is of significant importance. See the Gardens Group.

Animal activities are influenced by fruit-fall. Insect pest migration may be important (Worner et al. 1995).

Fruit quality (ripeness, energy content, etc.) for animals is a function of fruit duration on the plant before fruit-fall( Lugo and Frangi 1993)

Quality of fruit is influenced by freezing (e.g., persimmon)

The date of opening snd closing of the growing season, thus the length of the season in days is of great importance throughout agriculture.

The timing and length of the growing season control the spatio-temporal dynamics of critical carbon and water cycles.

Human recreation pleasure may be influenced by the onset of pollen release

The year-around life cycles of invertebrates are essential knowledge for the stream ecologists of The Fishery, those interested in bats (the nighttime workers of the Owls Group), and the migratory forest birds as part of Avi.

Jones (1962) observed that during different seasons of the year, animal species frequently use different components of their habitat. He observed this in the greater prairie chicken Tympanuchus cupido pinnatus and studied whether the availability of green plants as food might be a determining factor in daily movements, at least in winter months. The short-grass association greened up earlier than the tall-grass association. Japanese brome is available in late winter and early spring, more available in the short grass association. Cyperus is most available in December and January in the tall-grass association.

Bat behavior is insect related and hibernation temperature and other-factor regulated. Day-night phenomena are also of interest especially those related to night time as faunal cover.

Interannual Variability
Observations are often made with solar forces. Rural Timing also studies Lunar Forces.

One procedure for observing influence of a factor on an event is, after an arbitrary date, say Jan.1, mean air temperature or soil temperature above an arbitrary threshold (usually 0 or 5 degrees C) is summed until a critical value is exceeded, at which point the prescribed phenological event is predicted to occur.

An approach to a temperature statistic is: Days since Nov. 1 when T = (max + min) / 2 equal to or less than 5 degrees C. For tree buds terminal buds can be scored within a few days:

New Internet capabilities suggest the potential for Rural Timing to cooperatively build a set of observations of a select group of events, perhaps 10, and that members will contribute to the growing data base. It may have automated data entry and an auto-revised model made available to paying members.

One of the key results will be a growing precision in knowledge of the local growing season - degree days found so critical to crop plant suitability for sites, to insect pest abundance, and amphibian population abundance. BirdCast may provide a suggestion for a format to follow migrations.

White et al. 1997 observed that for many crops, phenology models based solely on natural climatic cues are unlikely to be adequate predictors. They said "Meteorology is a variable driver for phenological models" and that "it is extremely difficult to obtain consistent field phenology observations across landcovers which represent ecosystem activity rather than species-level phenology."

White et al. (1997) developed models which may be explored for use and presentation to members and for results for sale, and for use in the Pasture and Rangeland Group. They observed that " for the major North American deciduous landcovers, traditional meteorological models can be used to predict satellite-observed dates of on set and offset of greeness with errors of about 1 week maximum critical errors of of 10-14 days, and no significant bias.

Combined tenperature and radiation summation seems to be a major technique to pursue. Latitude within the US has little effect (photoperiod is relatively constant and not critical in modeling).

Most trees must fulfill a chilling requirement before warmer temperatures begin to affect springtime growth. (Thus straight-forward single-factor regressions cannot be sufficient for modeling.) (Murray et al. 1989)

The average annual air temperature of 9 to 9.5 degrees C seems critical for different grasses to green. Sims stated that 10 degrees C is the division between grasslands dominated by cool season grasses (C3) and warm-season grasses (C3) Different grassland life forms may require dramatically different thermal summations to induce onset of greening. Drought or cold weather can curtail greening, thus denying the average model.

Major topics: germination, leaf development, flowering time, fruiting time, seed dispersal, senesence, and leaf drop.

Sample measurements:

  1. Lilac first leaf
  2. Oak leaf drop
  3. Tulip poplar leaf expansion
  4. First day of grouse drumming
  5. Arrival of geese
  6. Daffodil full bloom

See Giles ecology notes.

  1. - slightly swollen
  2. - swollen
  3. - green foliage showing
  4. - elongated


White, M.A., P.E. Thornton, and S.W. Running. 1997. A continental phenology model for monitoring vegetation responses to interannual climatic variability. Global Biogeochemical cycles 11(2):217-234

Jones, R.E. 1962. The quantitative phenology of two plant communities in Osage County, Oklahoma, Proc. Oklahoma Acad. Sci. 42 (Biological Sciences):31-38

Kochmer, J.P. and S.N. Handel. 1986. Constraints and competition in the evolution of flowering phenology. Ecological Monog. 56(4): 303-325

Lugo, A.E. and J.L. Frangi. 1993. Fruitfall in the Luquillo experimental forest, Puerto Rico. Biotropica 25(1): 73-84

Motten, A.F. 1986. Pollination ecology of the spring wildflower community of a temperate deciduous forest. Ecol Monog. 56(1):21-42

Murray, M.G. R. Cannell and R.I. Smith. 1989. Date of budburst of fifteen tree species in Britain following climatic warming, J. Applied Ecol 26: 693-700.

Taylor, F.G. Phenological records of vascular plants at Oak Ridge Tennessee, Oak Ridge National Laboratory, ORNL-IBP-69-1 (UC.48 - Biology and Medicine), Oak Ridge, TN 46p.

Worner, S.P., G.M. Tatchell, and I.P. Woiwod. 1995. Predicting spring migration of the damson-hop aphid Phorodon humuli (HomopteraLAphididae) from historical records of host plant flowering phenology and weather. J. Applied Ecol. 32:17-28.

Perhaps you will share ideas with me about some of the topic(s) above .

Rural System
Robert H. Giles, Jr.
July 3, 2005