Changes in parameters
Even though parameters may change significantly over the course of the monitoring period, in all likelihood these changes will have relatively little influence on results overall.
However, a concerted effort must be made to provide scientists with information concerning the error margins for measurements, analyses and observations. This is even more important when measurements are carried out over the long term.
Nearly every domain the network monitors has its own Quality Assurance/Quality Control (QA/QC) programme whose objectives include defining, whenever possible, the margin of error associated to each type of data.
Though the work behind guaranteeing quality standards often goes unnoticed, it is at the heart of our scientific monitoring network.
Who is involved in quality assurance?
The work involves all the 240 ONF employees who participate in the network, plus outside experts and high-standard analytical laboratories (accredited by the Cofrac, the French Accreditation Committee).
Different levels of efficiency for the QA/QC programmes
- High-performance quality domains
the climatology network, sampling and water analyses, soil and foliar analyses, dendrometry, floristic observations, ozone and ammonia concentrations
- Medium-performance quality domains
forest health observations, litterfall sampling
- Domains where QA/QC programmes are nearly impossible to establish
phenology, mushroom surveys
A closer look at two quality assurance programmes
- The meteorological network
All of the weather sensors in the network are calibrated once a year. Each sensor is therefore monitored throughout its life span and changes in measurement error are taken into account.
We are therefore able to determine whether a positive or negative trend in a given meteorological parameter (for example, rainfall level) is significant or not.
- Observation of changes in floristic composition
These observations are carried out by expert botanists.
Each expert has been familiarised with abundance-dominance observations and has excellent knowledge of forest flora. Even so, when several experts carry out observations on the same plot, differences may appear as to the number of plants observed, the species identified and the abundance-dominance level assigned.
In this case, the QA/QC programme determines and quantifies these differences so that the analysis of any changes in floristic composition reflects reality as closely as possible.