The Netherlands Is Losing Its Insect-Pollinated Flowers

A wide range of plant species rely on insects for pollination, but the diversity of these insect-pollinated plants have decreased dramatically in recent decades

A newly published study from the Netherlands documents the ongoing loss of plant species that rely on pollination by insects and other creatures. This study, based on almost 90 years of data, sounds the alarm for biodiversity and food security.

Of course, this is not a surprise for many of us since it has been widely reported for decades that insect populations around the world have been declining.

“With this research, we show that there are also fewer and fewer plants dependent on those insects for pollination,” said ecologist Kaixuan Pan, a doctoral student at Leiden University, where he studies the mechanisms for how land use and climate change affect biodiversity, and how to sustain biodiversity, especially in human-modified landscapes.

“The proportion of insect-pollinated plants has declined while that of wind-pollinated plants has increased.”

Wind-pollinated crop plants include wheat, rice and corn whilst insect-pollinated crop plants include tomatoes, peppers and a wide variety of berries. In fact, 75% of all crops and 90% of wild plants in the Netherlands rely on insect pollination.

“Losing these species would pose a threat to our food security,” Mr Pan said.

Additionally, wildflowers and fruit trees are insect pollinated. But 22% of insect-pollinated plants have already gone extinct between 1930 and 2017, according to previous work by Mr Pan (ref). These extinctions were mainly due to the effects climate change and intensive agriculture.

“If these plants disappear from the landscape, it not only means fewer plant species remain, but also significantly fewer seeds and fruit for birds and other animals,” Mr Pan explained. “In other words: a significant decrease in biodiversity.”

This study relied on analyzing a vast amount of data.

“Kaixuan data mined 87 years of data collected from a staggering 365,768 plots to find as many trends and patterns as possible,” said Mr Pan’s supervisor and study co-author, ecologist Geert de Snoo, a professor of conservation biology at Leiden University, whose research focuses on biodiversity and sustainability in rural areas.

“We looked at different plant species but also factors like nitrogen, moisture levels, and pH, combining that with insect data,” explained Professor de Snoo. “This combination, and the large time scale, make this research unique.”

But how do the scientists know that insects are the key to the loss of these plants, and not factors like moisture or nitrogen?

“Within the same habitat type, under the same conditions, we often saw a greater decrease in the number of insect-pollinated species compared to wind-pollinated species,” replied Mr Pan. “So that difference is likely due to a lack of pollination: there are not enough pollinators left to provide these plants with sufficient pollen.”

So what can we, the public, do to help these important plants and their pollinators? There are a number of actions that can be taken to reverse the trend, explained the researchers. For example, reducing the amount of nitrogen released into nature can help.

“If we ensure that less of it ends up in nature, it can help local plants and insects,” replied Mr Pan, adding that it’s also important to safeguard natural grasslands. “Because they harbor many of the insect-pollinated plant species that have experienced declines in recent years.”

Mr Pan’s co-supervisor, environmental biologist Koos Biesmeijer, a professor of Natural Capital at Leiden University and the scientific director of the Naturalis Biodiversity Center pointed out the value of involving the local community in monitoring the diversity of both plants and their pollinating insects over time.

“[W]e must continue monitoring to see if these protection measures have the desired effect. Both on insects and plants, because they are interdependent,” Professor Biesmeijer said. “That way, we can learn from the past, monitor the present, and positively change the future.”

“It’s important to involve everyone because this problem will ultimately affect us all,” agreed Mr Pan.

Source:

Kaixuan Pan, Leon Marshall, Geert R. de Snoo, and Jacobus C. Biesmeijer (2024). Dutch landscapes have lost insect‐pollinated plants over the past 87 years, Journal of Applied Ecology | doi:10.1111/1365-2664.14649

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