Summarizing values to Describe Plant communities
Summarized Descriptive Variables
The first set of numbers obtained in an assessment of vegetation are called
Raw DATA or Field Values. Getting good raw data depends on:
- Site selected for study
- Method or protocol used
- Skill of field technician
- Quality or type of field equipment
- Field conditions at the time of study
- Etc., etc., etc.
The next step to getting an answer is to summarize the data and
create a data summary. Data summaries often include descriptive
statistics such as:
- Mean or average
- Median value
- Standard error or Standard deviation
- Minimum and maximum values
- Etc., etc., etc.
The goal of vegetation assessment is to interpret field data and make
decisions about the status or condition of the plant community relative to
management plans or conservation goals. But, to get a clearer picture of
what is going on, we often create new variables that combine the raw or
summarized data in ways that will facilitate interpretation. These
descriptive
variables include a whole range of indexes, ratios, quotients, rates, and
combined terms including:
- Relative abundance
- Species composition
- Diversity
- Dominance
- Similarity
Many summarized descriptive variables are well described with set parameters
such as the Shannon-Weiner Index of Biodiversity. However, you are free to
summarize and combine field values in any way that will help to "tease out" or
make apparent the trends in the plant community that you are trying to
ascertain. |
