Presence / absence surveys
This monitoring technique is used to determine whether a species is still present at a site. It is often used in conjunction with other monitoring techniques since when visiting a species population you are likely to collect other data in addition to just recording its presence or absence. It is also used for initial inventory as a precursor to starting a more detailed and intensive monitoring programme or when following up on threatened plant translocations or historic records of a species occurrence. It can be useful for species that are lower management priorities but that you wish to keep a watching brief over such as naturally rare species.
Before starting, those involved in the survey must be able to identify the species accurately. It is important to know what the species looks like (both fertile material and vegetative characters) so that the survey can be completed even when the species is not in flower or fruit. It is also important to have some idea of the species habitat and ecology. The reliability of the original record should also be checked. If a herbarium specimen was collected in the past check the species identification and obtain whatever additional information is possible, often written on herbarium vouchers, about where to search. It can be useful to involve someone in the search who has previously visited the site such as the person who originally collected the herbarium specimen. A GPS (Global Positioning System) can also be used, in some environments, to navigate to where plant populations have been previously recorded.