Phenology is the study of timing of biological events (e.g. budding, reproduction) that are influenced by environmental changes. The timing of these events is usually critical to ecological processes such as species interactions, productivity, germination and establishment, and senescence and dormancy. For example, flower blooms must coincide with pollinator availability. Phenology is organism centered, meaning that the organism indicates whether they perceive a cue or not. This field is of particular importance because phenology events are very sensitive to global change.
Phenology monitoring occurs in the BioCON plots, examining variation across increased carbon dioxide, increased nitrogen, and biodiversity plots. Data was collected on species emergence, height, flowering time, and senesce for three individuals of each species per plot, and percent cover and percent of flowering individuals were measured for each plot. Measurements were collected weekly on all monocultures and high diversity plots (9 species in 2007, 16 species in 2008) from April to August in 2007 and will hopefully continue through September or October in 2008. Species belong to one of four functional groups: C3 grasses, C4 grasses, forbs, and legumes.
Phenological differences occurred at the species level and were not consistent for functional group. For example, while one forb (Asclepias tuberosa) showed delayed response in flowering in response to increased nitrogen, another forb (Achillea millefolium) showed accelerated flowering under increased nitrogen treatment. While some species had differences in flowering time in response to treatments of CO2, nitrogen, and diversity, many species had no response. Many more years of data are needed to reveal true responses beyond yearly variation.
Similar monitoring will occur within the BAC experiment plots to study the effects of warming on plant phenology.
In addition to direct monitoring, some of Cedar Creek’s experiments may yield interesting phenology information. Soil from a forest dominated by Northern Pin Oak (Quercus ellipsoidalis) was transplanted to open fields in order to study the belowground effects on Northern Pin Oak seedlings while maintaining an open aboveground environment. One group of seedlings received high quantities of forest soil and the other received low quantities. It was found that, as expected, forest soil had large effects on seedling physiology. Forest soil also had an unexpected influence on phenology traits that had previously thought to be under aboveground control: seedlings receiving high quantities of forest soil broke bud earlier.
In 2009, Cedar Creek became a member of the National Phenology Network (USA-NPN), which is a large-scale nationwide network of integrated phenological observations. The USA-NPN is composed of federal agencies, environmental networks and field stations, educational institutions, and citizen scientists participating en masse. Because of its unique location near the ecotones of three large biomes (western prairies, northern boreal forests, and eastern deciduous forests), data on species at Cedar Creek can be compared with many US sites east of the Rocky Mountains.
Soon Cedar Creek will be part of project PhenoCam, a 12-site network that monitors phenology on a semi-national scale. Project PhenoCam uses high resolution webcams to monitor phenological events using near-surface remote sensing. PhenoCam can help bridge the gap between phenological measurements taken through ground monitoring and satellite imagery.
