VMM - Inland water macrophyte occurrences in Flanders, Belgium

Study Extent

The present dataset originates from the macrophyte monitoring network of the Flanders Environment Agency (VMM). This network was developed in 2007 to meet the requirements of the European Water Framework Directive (WFD). The network encloses all Flemish water bodies where macrophytes are relevant water quality indicators, ranging from large water bodies (drainage area > 50 km²) to smaller bodies (drainage area between 10 and 50 km²). Data collection normally occurs every 3 years (large water bodies) or every 6 years (small water bodies).

Sampling

The period that is suitable for the monitoring of macrophytes in water courses is from the end of May to the end of September. Per water body, 3 not or little shaded stretches of 100 meters are inventoried; those trajectories are located in the upstream, the middle and the downstream part of the water body. All types of aquatic and riverbank plants present are noted on each route with their respective coverage or abundance. For each section of 10 meters, the global cover by submerged aquatic plants is recorded. For the entire 100m trajectory, the cover per species of aquatic plant is noted according to the Tansley cover scale. The species encountered, together with their abundance according to the Tansley scale, are noted on the field worksheet. Coverage is here understood as the vertical projection on the water surface of the surface occupied by each species. This is therefore a two-dimensional fact, different from the filling of the water column. The sum of the cover of all species can be more than 100% since the plants occur in different layers (e.g. one or more layers of helophytes, a duckweed layer and several layers of submerged plants). Only the species that take root in the water or the sediment are noted. Plants that grow in the (wet or dry) bank and hang over in the water without forming roots are therefore not noted. Based on that recording, four sub-measurements are calculated, namely the type specificity, the disturbance, the growth forms and the vegetation development.. The first metric gives an indication of the extent to which the plant community found is characteristic of the type of watercourse; the second indicates the degree of disturbance, mainly due to an excessive amount of nutrients (eutrophication).Certain species are indeed indicators for pollution and when their abundance increases, that negatively influence the dividing metric. The variety of growth forms is indicative for the structure of water and riparian vegetation. Although aquatic plants into diverse systematic groups belong, they may have similar morphological features exhibits related to the environment. Based on the set of morphological features macrophytes are classified according to their characteristic growth form. Finally, the measurement vegetation development is the extent to which (only) the submerged aquatic plants develop.

Quality Control

The monitoring is based on the standardized VMM procedure for the monitoring of macrophytes in flowing waters (VMM/WAT/GP/3.111). Based on the ISO14001 standard all co-workers are intensely trained for monitoring and determination of aquatic plants. On a regular basis, audits are performed to evaluate the monitoring protocol as a whole.

Method steps

1. The source data for this standardized sampling event dataset is managed by the Flanders Environment Agency (VMM).
2. An SQL script was developed to transform the data to Darwin Core. This mapping script was uploaded to a GitHub repository (https://github.com/riparias/vmm-macrophytes-occurrences/tree/main/sql) and includes the following steps:
3. Perform some basic data cleaning of the raw data
4. Generate stable and unique identifiers for each occurrence (occurrenceID)
5. Create an event core file with all sampling events (https://rs.gbif.org/core/dwc_event_2022-02-02.xml)
6. Create a occurrence extension file (https://rs.gbif.org/core/dwc_occurrence_2022-02-02.xml)
7. Create a measurement or facts extension file (https://rs.gbif.org/extension/dwc/measurements_or_facts_2022-02-02.xml)
8. The resulting Darwin Core files are uploaded to the INBO IPT and documented with metadata.
9. The dataset is published and registered with GBIF.

The sampling focus of this dataset is inland macrophytes.

1. Plantae
   common name: plants rank: kingdom

Flanders