SLU news

Intensive agriculture results in less reliable weed control from seed eaters

Published: 17 April 2024
Dandelions in an agricultural field. Photo.

To increase crop productivity, agriculture relies on intensive use of chemical pesticides and fertilizers. In a new study, researchers show that with intensive agriculture, there is a risk of losing stable supply of important ecosystem services such as weed seed predation.

Agriculture is intensified across the globe with the help of pesticides and fertilizers. At the same time, crop species diversity decline and the landscape gets simpler. These disturbances leads to biodiversity loss and less pollination and biological pest control in the fields.

It is expected that a high biodiversity can compensate for a lost species by relying on another similar species to deliver the same ecosystem function. This is called functional redundancy.

How is weed seed predation affected by disturbances?

However, we do not know how the agricultural intensity affect the functional redundancy and its link with ecosystem function stability. Therefore, SLU researchers together with colleagues from other parts of Europe, have assessed how functional redundancy of weed seed predation is affected by agricultural intensity and landscape simplification. Predation of weed seeds by seed predators such as carabid beetles is an ecosystem function that contributes to biological weed control.

– We investigated the abundance of carabid beetles and combined it with molecular gut content data to estimate the functional redundancy of seed predation. Analysing the carabid beetles’ diet is a powerful tool to find out what their role is in agroecosystems, says Eirini Daouti, one of the researchers behind ths study.

Intensive agiculture reduced weed seed predation

The functional redundancy of weed seed predation was quantified for 65 weed genera across 60 fields in France, Austria, Czech Republic and Sweden.

– We found that increased field management intensity, measured as the number of visits to the field to do management interventions such as herbicide application or tillage, and reduced crop rotation diversity reduced the functional redundancy of weed seed predation. We did not see an effect of landscape simplification in this study, says Mattias Jonsson, another researcher behind the study.

– Ecosystem functions are vulnerable to disturbances in intensively managed agroecosystems. Our results shows how important it is to maintain biodiversity to safeguard resilient ecosystem functioning, concludes Eirini.

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