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Gradiënts in species occurrences

along the green-blue recreative network between the surrounding counties of Leiden and the Singelpark as indication of their corridor function for biodiversity.

Marco Roos (Naturalis) and Wil Tamis (CML)


Period & duration
6-12 months, preferably including the flowering season (in consultation)

Study & level
Biology, MSc & BSc

Background & context
The “Leidse Ommelanden” is a LEADER project to enhance the the quality of life and the sustainable economy of the rural areas around Leiden, as well as improving the connections between Leiden and its surroundings. Restoring ecosystems and improving biodiversity is part of the goals. For this purpose a.o. a green-blue recreative network is being further developed. The central axis is formed by the Singel park. This network is also regarded as corridors for biodiversity, providing species better dispersal routes and connecting local (regional) hotspots, for instance between the peat landscapes and the beachplanes, and between the estates on Old beach ridges south and north of Leiden.

Objectives & goals
The objective is to get better insight in how effective this network is as biodiversity corridors connecting Leiden with its surroundings and the regional hotspots. For this purpose, biodiversity patterns along the gradiënts of these corridors between the surrounding country and the Singelpark have to be mapped and analysed in detail. Many ecologic and antropomorphic factors play a role, e.g. differences in management of sites and mobility of organisms. Therefore, representative, informative and comparable plots along the corridors have to be selected, as well organisms with dispersal capacities matching the scale of the corridors.

Relevant objectives include:

-          Do the green connections between Singelpark (Centre Leiden) and the surroundings of Leiden function as ecological corridors for flora and fauna?
-          The role of green roofs in the green network structure of the city of Leiden.
-          The effectiveness of “bee hotel” for the conservation of solitary bees in Leiden and surroundings.
-          Monitoring of nectar and pollen producing plants in extensively managed field margins.
-          Monitoring breeding birds with a simplified survey-instruction.

A second objective is a plan for Citizen Science, incl. possible indicator species, target group and approach. When data are available, a comparison can be made of a Nature value scoring through citizen science (CS) and conventional methods of vegetation monitoring.

A special project in this respect is focusing on monitoring 25 characteristic ditch bank plants to evaluate the quality of ditch vegetations. This project builds on earlier internships which resulted in a baseline inventory of a representative number of transects along the blue corridors in and around Leiden resulting in a general view on the status of the existing vegetations and species relevant for monitoring. The purpose is of the present internships is to refine the selection of plant species to a limited number of species informative for ecological monitoring and suitable for Citizen Science, and to test this selection in an analyses of the status of the vegetations present and their succession prospects.

Methods, tasks and approaches
First, compile relevant available data bases and expand these with inventories of selected taxa. Statistically analyze the patterns in species occurrence along the gradients. Interpret the patterns found in view of the corridor function of the transect of plots.

Various parallel student projects can be carried out focusing on different taxa.

biodiversity courses