Oeverplanten
For many people spring is associated with the awakening of nature. The trees begin to paint the backdrop green again, welcoming the beginning of a new season with the chorus of frogs and bees, and the scent of flowers in the air. For Jaqueline Henrot, researcher at Naturalis Biodiversity Center and environmental consultant, spring also heralds the start of “Oevercheck” season.
The “mijnOeverplanten” project with its ‘Oevercheck’ looks at plant vegetation diversity along canal banks in the Netherlands. Over the years, this Citizen Science project gained more and more popularity and engagement with the public, with an increasing number of participants. Volunteers are asked to do riverbank checks, which is the recognition of 23 plants along the canals that are indicators of soil health. Now 5 years old, 3200 river banks have been mapped.
Over-fertilization and high Nitrogen concentration in the environment are well-known problems in the Netherlands. Highly fertilised soils make fast-growing plants thrive, such as grass, nettle, and hairy fireweed, which can thus become dominant and take up all the space and sunlight at the expense of plants such as the common fleabane orchid, which actually prefer poorly fertilised soil. This results in a lower variety of plants along the banks of freshwater ways, which also translates into low biodiversity overall.
To try to overcome this problem, about ten years ago the Municipalities around Leiden wanted to improve biodiversity along cycling routes. They then started to put effort into managing canal banks, by removing part of the vegetation. Plants while they grow take nutrients from the soil, by eradicating them you can impoverish the soil. With controlled mowing along the banks, you can then make the soil less fertile and improve plant diversity.
Also, the management of the bank shapes has an impact on vegetation richness. In steep banks, there is no gradient of moisture and with that no variation of soil humidity and vegetation diversity associated with that. In banks with a gradual slope, all sorts of soil humidity and habitats can be found, and with that a higher plant richness.
Whether these efforts of management actually had an impact on biodiversity was still unknown, the Naturalis Biodiversity Center and the Center for Environmental Sciences of Leiden University approached the municipality of Leiden to engage them in a research project to find out - and with the involvement of Dr. Henrot, this became the Oeverplanten project.
24 plant species are used as indicators to measure vegetation quality. These are indicative of different levels of soil fertilisation and bank management and they are grouped into three categories: red, which are fast growers’ species that need a high fertilised soil, orange and yellow, which tolerate in-between fertilisation concentration, and green which are species that live only in poor soils. Based on the presence and abundance of these, the water site is given a red, yellow, or green label, representative of the soil health conditions and banks’ status of management.
Each transept is about 40 metres long and takes about 15 minutes to do. The plant recognition is accessible to everyone, and educational materials such as pictures, plant descriptions, an informative app, and quizzes are available on the Oeverplanten website. If needed, further support is given by the ObsIdentify app, which can provide the plant species by uploading a picture.
Soil restoration takes time, that’s why this project needs ten years of monitoring to see the concrete outcomes. The hope is that municipal efforts to decrease soil fertilisation will be observed over the years with an increase in vegetation diversity, and banks that were at first categorised as red or yellow might become green.
The data collected by Oeverplanten are not only then provided to the Municipalities, but also made available to everyone in open data format. Over the years the project has received media attention, such as in the national news publication Trouw and on local TV broadcaster Unity TV, leading to interest from across the country, and requests to perform ‘oeverchecks’ in other parts of the Netherlands. What started as a local project in Leiden has now grown nation-wide.
For Henrot , the form of Citizen Science was a logical choice for this project, because it wouldn’t be financially possible for the municipality to collect so much data on its own, let alone one single researcher. Additionally, involving the public has the advantage of raising awareness of the importance of biodiversity, their own role in maintaining the natural environment, as well as the measures that the municipality takes to maintain and manage green spaces. For example, the logic behind letting grasses and weeds grow tall alongside pathways is to maintain biodiversity, support crucial pollinators, and to remove excess nitrogen when those plants are removed.
“If you don’t know it you don’t value it” she adds. People in their garden or environment often don’t realize the different natural values that tiles, exotic plants, horticultural plants, and natural plants have. They have to change their minds from a nicely coloured pot where everything is clean to a scene where nature is a place itself.
To other researchers interested in setting up a citizen science project, Henrot suggests having a clear goal right from the start. Education is not a strong enough reason to start these types of projects, the science behind it has to be useful and the research question clear. She suggests having a clear target audience and subject, as well consider the complexity and duration of the activities you are proposing. There are many CS projects now proposed that the public is becoming saturated, and the new project should therefore be carefully designed.