Levels of information collected in surveys

Levels of information collected in surveys

Here's an example of some of the different levels of information that you might collect about a species of plant as part of a biodiversity survey of an area. The hypothetical example refers to populations of the Darwin Stringybark tree Eucalyptus tetrodonta.

Levels of information	Example
Presence?	present
Qualitative description of abundance	common
Qualitative description of abundance and habitat preferences	common, mainly on rocky hillsides and growing with Darwin Woollybutt E. miniata
Quantitative description of total abundance	1,783 trees
Quantitative estimate of abundance	34 ± 12 (s.e.) trees per ha
Quantitative estimate of abundance and habitat preferences	in vegetation type a., 55 ± 7 (s.e.) trees per ha; in vegetation type b. 3 ± 1.5 (s.e.) trees per ha
Quantitative estimate of size and abundance etc.	In vegetation type a.: 0 - 1 cm dbh* - 1,350 ± 780 (s.e.) per ha 1 - 5 cm dbh - 256 ± 52 (s.e.) per ha 5 - 10 cm dbh - 132 ± 22 (s.e.) per ha 10 - 25 cm dbh - 48 ± 13 (s.e.) per ha 25+ cm dbh - 2 ± 1.6 (s.e.) per ha etc.

* s.e = standard error, a statistical measure of our confidence in the estimate of the mean or average

* dbh = diameter at breast height