Measurements and Plant Attributes
Natural Resource Measurements
the decision to monitor a resource has been made, it is necessary to then
decide how best to measure the features of interest. A natural resource
inventory is where we take measurements to obtain dimensional or physiological
information about the resource. For example, we could be interested in
quantifying the amount of carbon sequestered by a
forest in a given year or the amount of water used by a shrub species in a
A natural resource inventory can be defined as the process
of estimating a specific natural resource (e.g., tree height, grass
cover, etc.) as precisely as your available resources (time, money, personnel,
etc.) can permit. In forestry, a forest inventory normally focuses on assessing the volume or value of standing trees
for different forest products. In rangeland management, shrublands and
grasslands are assessed to determine attributes such as carrying
capacity for livestock or wildlife, invasive plants, and rare or endangered
species. Vegetation characteristics from forest, woodlands, shrublands, and
grasslands may also be inventoried and assessed to characterize fuel
load for prescribed fire or fire risk.
Clearly, there is never enough time, money, or resources to
measure the characteristics of every feature of the vegetation in your area
of interest. A further limiting factor may be that the
extent of your study area may be too large or too remote for
your available personnel to accurately inventory in the allotted time. This is
why we typically measure a subset of plants called a
Plant Attributes to Measure
There are many ways to measure plants, but, there are only
about 6 "attributes" that are commonly measured. Vegetation
attributes are characteristics of vegetation that can be measured or
quantified referring to how many, how much, or what kind of plant species are
present. The most commonly used attributes are:
Plant Species or Type - What kind of plant was it?
Frequency - Was the plant there or not?
Density - How many plants were there?
Biomass - How much did the plants weigh?
Cover - How much of the ground surface did they cover?
Structure - How tall were the plants and how were
branches and leaves arranged?
We can also make observations about health,
vigor of individual plants or plant communities. And we can combine
the above attributes to create variables such as species
biodiveristy of the site, or similarity with historic
measurements or other sites.
**The major plant attributes will be more fully described in
later portions of this class.
Natural Resource Measurements: Taking Care
important introductory concepts of natural resource measurements are to:
Because time is nearly always a limiting factor, are there ways
and strategies to make wise decisions about what to measure? Can field
and data analysis habits be gained that will create as much useable data
YES... of course. There are several steps you can follow to make the best use of
Clearly specify each objective.
Be familiar with the possible and appropriate tools for each task.
Practice the correct use of each tool before going to take
Take repeated measurements.
Record measurements on carefully designed field forms.
Check that your answers are sensible.
Importantly, if a correctly applied measurement produces an
value -- donít ignore or remove it. The apparently incorrect
measurement may be a new discovery. In general, data points
should never be removed unless you have a really good reason (e.g.,
contaminated sample). In essence, a considerable quantity of important
scientific discoveries have been made due to apparent mistakes that produced