Arctic Borderlands Ecological Knowledge Co-op
Indicator Assessment: Plant Indicators of Climate Change
Introduction and Summary
Plants respond to variations in climate in many ways. The type of response that is noted often depends on the time scale examined. On the scale of days and months, plants may respond to variations in weather patterns with variations in phenology (the timing of individual development stages in the life history of a plant). The use of phenological timing as an indicator of climate change within the context of the Arctic Borderlands Ecological Knowledge program is being discussed elsewhere.
On a time scale slightly longer than that within which individual phenological events occur, plant responses may be quantified as productivity responses, i.e. vegetative growth or reproductive output achieved within single or multiple growing seasons. To observe this, measurements of productivity must be made within the life-span of a target plant individual or plant part. In most cases, measurements of annual productivity require at least one or more observations to be made during a growing season. In cases where plants exhibit growth patterns which delimit annual growth increments, such as bud scars, measurements of productivity may be made retrospectively over the discernible growth record of a plant. Both repeated field measurements of productivity and retrospective growth analysis are discussed in this report.
Over time scales longer than a few years, the productivity of populations in response to climate change becomes of interest. Ultimately, it is plant responses on the population level which determine how plant communities will respond to perturbations such as climate change. Plant population responses may be quantified as changes in rates of recruitment (vegetative expansion, seedling establishment), mortality and immigration. These factors can be studied either through observations of a population at a single time, or through repeated observations of individual plants within a population over time. Methods for studying population dynamics in the natural environment generally require very intensive measurements, but some factors may be studied with much less effort and although they may not be able to provide as complete a picture, substantial information may be gained. Retrospective analysis, mentioned above, may also be useful for extending the amount of information which may be obtained from observations made at a single point in time. Methods of monitoring plant population dynamics as indicators of responses to climate change are addressed below.
Contents of this report:
Because this is a long and technically detailed document, we have not posted it in its entirety on this web page. If you would like to read the full report, please contact us.
Written by J. Johnstone, January 1997.