“The shrub with the poor nitrogen picture is actually a native topper that is good for biodiversity”

Blackberries are known as a sign of disruption in nature, especially nitrogen. Unjustified, thinks researcher and blackberry enthusiast Rienk Jan Bijlsma. Walking through the Rijk van Nijmegen, he defends his beloved plant.

The average hiker on the Sint-Jansberg in the Limburg village of Plasmolen will quickly pass the edge full of pungent blackberries. But Rienk Jan Bijlsma, a researcher at Wageningen University, is stunned. “It’s now a beautiful rose, just that color. You can also see bees and bumblebees around it. Blackberries are also an important source of nectar for butterflies.

It’s clear that Bijlsma sees the value in blackberries, but that’s not really the case for the rest of the Netherlands. Take the nitrogen debate. Many politicians simplify the result of nitrogen deposition in nature to “nature with only nettles and blackberries”.

But blackberries also spell trouble for nature managers. “Blackberries and nettles, it quenches well and has therefore been used for years as an example of disturbance in nature. But that’s not always the case,” says Bijlsma. “Especially in places where it’s naturally humid and not anymore you get bursts of smudges there. But that says more about dehydration than nitrogen. And in most places it’s just part of the vegetation adapting to it, they’re Dutch nature.

An essential part of Dutch nature

Together with two other researchers, he wrote a pamphlet on the value of blackberries in Dutch nature. The title Bramenland Netherlands says enough. “Blackberries are an essential part of Dutch nature, in our climatic region the blackberry is simply part of it. They are found much less in the east in Germany or in southern Sweden.

Moreover, “the blackberry” does not exist; The Netherlands has more than two hundred different species. The wide variety of blackberries goes hand in hand with a wide variety of specific growing locations, ranging from acidic to chalky and nutrient-poor to nutrient-rich. “It’s a very interesting group, also from an ecological point of view,” continues Bijlsma. “Blackberry enthusiasts sometimes say, ‘you can throw us out of the car anywhere in the Netherlands and I can tell by the blackberries where I am in the Netherlands’.”

Since the Ice Age, blackberry plants have evolved from just a few species per landscape, he says. “As a result, you have species that are specifically adapted to dry poor soils, somewhat richer soils, wetter rich soils, etc. Each landscape therefore has its own combination of blackberry species. If I walk around here, I could quickly tell that we are in the Rijk van Nijmegen.

The red female dog

Bijlsma specifically took us to this location, about ten kilometers south of Nijmegen, due to the rich blackberry species and the area’s ancient forest history. “All the forests here are remnants of what was once the great Reichswald, a forest that stretched from Nijmegen via Beek-Ubbergen, Berg en Dal, Groesbeek, eventually into Germany, the part that is still called Reichswald. It is an incredibly old forest and you can tell that by the plants that live there.

“Blackberries are traditionally common here. You hardly see blackberries on the Veluwe. This is partly because deer and roe deer eat it, but also because it is naturally too poor. Where we are now you have loess soil, which is ideal for blackberries. An estate with a long history of blackberry research. In the 1950s, Nijmegen biologists Kern and Reichgelt were the first plant scientists to take an interest in blackberries in the Dutch wild and take a closer look at the wider environment.

“They called this species with pink flowers ‘the red bitch’, because they met it everywhere around Nijmegen, but could not name it. It turned out that it was a species that had not yet been described. It later received the scientific name Corpse Rubus rubrumso the red female dog.

Set of blackberry varieties

After talking about blackberries, Bijlsma does not stop. “Look, here you see the typical shoots with only leaves. They will only flower next year and then take roots at the top which will sink into the ground. The old part then dies. In this way, the blackberries cross the forest and can thus reach the most favorable places. Special, right?”

Later, Bijlsma shows how blackberries are part of a plant community that corresponds to a forest edge. “You see false sage, honeysuckle, field rush, valley grass and so one or two types of blackberries to go with it.” In the forest itself, there is a species that Bijlsma would like to show: the log bramble, a kind of old forest. “The Netherlands has a blackberry group that remains much smaller than most blackberry species and often grows in smaller numbers on the forest floor. It is a species only found in the ancient forests of Drenthe, South Limburg and here in the former Reichswald.

Bijlsma takes a step back and makes an imaginary list with her hands. “Look at that old oak tree, that fern, then that forest bramble. This image is really a set of the Niederreichswald. This gives an area extra natural value!

These species not only have intrinsic value, they are also important to the ecosystem. Besides serving as a source of nectar, they also provide hiding places for various birds, mammals and tree frogs, and are used by locusts as a courtship arena. And then, of course, there is the fruit. These are not only picked by humans, but also eaten by birds, martens, mice and foxes. “I know of examples of mice that had a nest full of blackberry seeds, which shows how important that is for these animals,” says Bijlsma.

Misleading story

He calls on nature managers to be more careful with blackberries in their nature reserves and not to take the brush cutter too quickly. “Of course there are situations where you want to intervene, for example if there are blackberry bushes several meters high due to desiccation. But in most situations you should enjoy the blackberries and leave them that way.

And the bad reputation blackberries have as an indicator of excess nitrogen, isn’t that at all true? “That’s the case in some places, there are many nitrogen-loving blackberry varieties,” says Bijlsma. “And we certainly don’t want to minimize the consequences of nitrogen deposition, on the contrary. These consequences are huge, but you usually don’t read them from the amount of blackberries.

“In the forests and moors of the Veluwe, you don’t see a single bramble, but there the problems of nutrient imbalance due to nitrogen are enormous. So we think the blackberries and nettles story is misleading people. Report instead the skylark and the curlew which have disappeared from the moor. Ask why it’s quiet on the moor and there are hardly any bugs. These are the true consequences of nitrogen.

Read also:

From hare to sundew: these plants and animals are in danger zone because of nitrogen emissions

The large excess of nitrogen threatens the survival of species. And it’s not just protected and vulnerable plants and animals that are in trouble. Four examples.

In addition to nitrogen, also tackle phosphorus, scientists say. “In fact, more plant species disappear than if you do nothing”

One-sided attention to nitrogen is bad for nature, warn the Utrecht researchers, if phosphorus is not addressed at the same time. Phosphates in manure adhere to the soil and spread to groundwater and surface water.