Environmental Engineering Reference
In-Depth Information
Before any sampling protocol can be created, the goals of the project must be
clarified. Questions to ask yourself include:
Is this a one-time assessment, or would you like to track changes in the vegeta-
tion over time?
Are you more interested in one to a few different populations, the plant commu-
nity as a whole, or in plants as a production component of an ecosystem model?
What attributes of the vegetation are important to you? Presence or absence of
species? Abundance of individual species? Vegetation cover, height or biomass?
Dominance or importance of different species?
Is it important to have quantitative data that can be used in a statistically-valid
manner, or is a basic qualitative (e.g., a species list) description of the system
adequate?
Is characterizing the spatial pattern of the vegetation or having precise location
information important to answering your question?
Once you have considered and answered these questions, you will be able to
determine which techniques are best suited for your purpose.
5.3.1 Attributes of Vegetation
The basic building blocks of any sampling protocol are the attributes to be
measured. Once a system for selecting and delimiting sample locations has been
established, vegetation characteristics are assessed. Commonly-measured attributes
include:
Presence: Does the species occur within the plot or site? This measure can later
be used to calculate the frequency of a species within a site (the number of plots
in which the species occurred).
Abundance: How much of the species occurs? This can be measured in different
ways, such as by count of individuals or by visual percent-cover.
Production: How much biomass is produced by different species in the plot?
Root, shoot, and or total plant biomass can be measured.
Structure: How tall is the vegetation or how many stems or branching points are
produced? How much three-dimensional space is occupied by the plant? These
types of measures can be particularly helpful when assessing habitat for animals.
Composition: Which and how many different species occur within the plot?
Functional groups: What is the abundance of species from different functional
groups (e.g., perennial graminoid, annual forb, floating-leaf submergent)? Many
attributes, such as invasive or wetland indicator status, can be assigned after
sampling based upon available information (e.g., USDA Plants Database:
http://
Morphological characteristics: What types of traits does each species have?
Traits measured in the field include leaf number, leaf shape, specific leaf area,
and flower number.
