How it all started

Retired biologist Erik Vinther:

In 1980 I received my MSc in Biology from what was then the Botanical Institute, Aarhus University. My thesis was carried out as an investigation of the overgrowth in the fen in Hørret forest as a result of ceased grazing. The thesis resulted in a management plan for the fen, and from 1983 till now Aarhus Municipality has maintained nature conservation in the area. Immediately after completing my master's thesis in the summer of 1980, I laid out a 74-metre-long transect through the eastern part of the overgrown fen. I am very pleased that Aarhus University will continue the study so that the long time series can be expanded.

Globeflower. Photo: Kaj Halberg 05-06-1970 © — Globeflower on the outskirts of blackthorn shrub towards the northeast of the meadow. Today, globeflower has disappeared from the meadow. Photo: Kaj Halberg 05-06-1970 ©

Method

The transect stretches across an environmental gradient from the edge of the forest towards a small stream. The vegetation changes along the transect and was originally divided into three habitats: Alder forest habitat, meadowsweet habitat and the true sedge habitat. The transect is divided into 37 plots of 2x2m, where the vegetation is analysed by a coverage-level analysis. The analyses were carried out by Erik Vinther a total of 19 times at 1-4 year intervals, most recently in the summer of 2021. Measuring the water level along the transect also started here. The water level measurements have been carried out once a month until December 2022. Aarhus University, Department of Ecoscience, has taken over the time series in 2021. The continuation of the time series includes collecting and processing plant-abundance data from the fen every other year. The method for monitoring the 74m-long transect naturally follows Erik Vinther's original protocol. We will supplement Erik's original data set with measurements of soil pH and N/P measurements in leaves at 10-year intervals. Such environmental variables are important when we, through analyses, try to understand and interpret the changes that take place in the vegetation over time. We will also compare time series data with data collected via the National monitoring programme NOVANA and continuously collect information about management (mainly grazing) from the local cattle grazing guild and Aarhus Municipality, which owns Uller Eng.

In 1980 bogbean grew in 7 plots in the transect, but drastically declined in 1985 and was last seen in the transect in 1991. The reason for the decline was supposedly due to the fact that the ditches in the woods close to the meadow were cleaned up mid-1980 and the addition of groundwater to the meadow was reduced. Today, water levels have improved significantly, and bogbean is spreading from the spring source towards the transect. Photo: Erik Vinther 15-08-2022 ©

The broad-leaved marsh orchid is found in decent populations in Uller Eng. The largest population is probably in the spring, all the way to the east, but the species is also found in the seepage spring toward the northeast. The broad-leaved marsh orchid used to grow in a few plots in the transect, but overgrowth has meant that the species was last found in the transect in 2005. Photo: Erik Vinther 16-04-2020 ©

The ragged-robin is a common plant in meadows and fens. It is perennial, but the up to 60cm tall plant begins its first year as a small rosette with tongue shaped leaves. The rosette is sensitive to shadows from tall and dense plants, such as wood clubrush, lesser pond-sage and meadowsweet. The ragged-robin reacts very positively to hay harvesting and relatively intensive grazing, because they prevent the competitive species from forming dense populations. Light can access the ground, so the seeds from the ragged-robin can germinate and the rosette can survive its first year. In the period 1983-1987, Uller Eng was mowed every year, and the hay was collected and removed. This was optimal for the ragged-robin and the population increased (found in two plots in 1980 and 21 plots in 1987). Until 1997, the species spread to 28 plots, but then grazing became more extensive, and for two years the meadow was completely without grazing. The ragged-robin population decreased and was only found in 15 plots in 2009, 9 plots in 2017 and 7 plots in 2021. Photo: Erik Vinther 29-08-2021 ©

Carex dioica has only been found in few fens in Aarhus Municipality. As is implied in the name, both male and female plants exist. The slender plant is most likely found in the spring towards the east from late May to mid June. Outside the flowering and fruiting season, the species is very easily overlooked. Photo: Erik Vinther 29-12-2016 ©

Monitoring plant communities

How it all started

Method