| Accuracy |
How close an estimate is to the parameter being estimated |
| Annual productivity |
Amount of living tissue created per year, less losses to respiration,
per plant or per area; productivity is one of the best measures
of a species's functional importance |
| Attribute |
A charactistic of an entity. For example, a tree (the entity)
has a certain diameter (the attribute), or a species (the entity) has a certain cover (the attribute) within a community. |
| Basal area |
The cross-sectional area of the tree's trunk at breast height;
stand basal area is the sum of tree basal area for the community |
| Baseline studies |
"Assessing existing conditions to provide a standard against
which future change is measured" (Elzinga et al., 2001) |
| Bias |
Systematic error; the difference between the mean of all possible
estimates given by an estimator and the parameter being estimated |
| Biomass |
Weight of living tissue, either per plant or per area. Biomass
is the best single measure of a species's structural importance. |
| Completely random design (CRD) |
A design for manipulative experiments in which locations suitable
for study are first identified, then treatments are assigned completely
at random |
| Confidence interval |
A range of values intended to include a parameter |
| Confidence level |
The probability (or confidence) with which one makes a statement
about an estimate |
|
Cover |
Amount of the ground obscured by the aboveground portions of
a species |
Total cover
|
Cover of all plants, ignoring what leaf belongs to which species
or group |
Combined cover
|
Sum of the cover values for different plant species or groups. |
Overall cover
|
Cover across the entire study area |
| Density |
Number of individuals per area |
| DBH |
Diameter of a tree trunk at breast height (1.37 m) |
| Efficiency |
The ability of a sampling design to produce precise estimates
with moderate effort; precision per time |
| Error |
The difference between an estimated value and the true value |
| Estimate |
A statistic that is used as a guess of the value of a parameter |
| Experimental unit |
A single item subjected to an experimental treatment; units
can be individuals or portions of area |
| Frequency |
The proportion of plots in which a species is found |
| Independence (of samples) |
The location of one sample does not affect the location of another |
| Inference |
The process of drawing conclusions about a statistical population
based on sample observations |
| Interspersion |
The distribution of samples across the community |
| Leaf area index (LAI) |
Surface area of leaves per area of ground |
| Manipulative experiment |
Comparative study in which the investigator creates differences
by imposing treatments |
| Measurement error |
The difference between the measured value of a single item and
its true value |
| Mensurative experiment |
Comparative study in which the investigator exploits pre-existing
differences; "natural experiment" |
| Monitoring |
"The collection and analysis of repeated observations or measurements
to evaluate changes in condition and progress toward meeting a
[scientific or] management objective." (Elzinga et al. 2001) |
| Net production |
Amount of organic matter created, less losses to respiration |
| Observational unit |
A single item being observed, also called a sampling unit; units
can be individuals or portions of area, sometimes delimited by
quadrat frames |
| Overall cover |
The cover of an entity over all observational units |
| Parameter |
A quantitative characteristic of the statistical population |
| Physiognomy |
Vertical and horizontal structure of a community |
| Precision |
The closeness of repeated measurements of the same quantity |
| Quadrat |
An area (of any shape) in which plant or vegetation attributes
are recorded |
| Randomization |
A way to eliminate subjectivity |
| Randomized complete block design (RCB) |
A design for manipulative experiments in which all treatments
are assigned at random to areas within blocks |
| Reliability |
When referring to data, reliability describes data with low variability. |
| Replication |
The repetition of equivalent measurements or treatments |
| Sample |
A part of a statistical population; a sample is usually taken
to estimate something about the whole population |
| Sampling error |
Inaccuracy in an estimate causee by variability among observations |
| Sampling unit |
A single item being observed, also called an observation; units
can be individuals or portions of area, sometimes delimited by
quadrat frames |
| Sampling universe |
The whole group of items under investigation; all possible sampling
units; sometimes called the statistical population |
| Simple random sample |
Sampling scheme in which each possible sample has the same probability
of being selected |
| Statistic |
A quantitative characteristic of the sample |
| Statistical population |
The whole group of items under investigation; all possible sampling
units; sometimes called the sampling universe |
| Stratified random sample |
Sampling scheme in which random samples are allocated to relatively
uniform subunits within a population |
| Surveillance |
Measuring change in the absence of scientific or management
objectives |
| Total cover |
(1) The cover of all plants considered as a group; (2) the combined
(summed) cover of all species (#2 can be more than #1 if species
overlap) |
| Variability |
The degree to which measurements differ from one another. |
| Zone of influence |
An imaginary boundary around a plant's crown, roughly representing the effects on the crown on the surrounding area, that fills in minute gaps within the crown and smooths its boundary. |
