Agriculture is one of the biggest culprits for declining biodiversity due to the conversion of natural areas into arable or pasture land. Scientists and conservationists are constantly debating how this trend can be counteracted and are putting forward two opposing concepts. But perhaps a combination of the two is the best way forward?
How can biodiversity in agriculture be increased? There are various approaches to this. One approach is to maximize yields on existing agricultural land, intensify conventional farming and establish nature reserves on separate areas. The other approach calls for agriculture that is not optimized for yield, is environmentally friendly and uses more land. However, land use is always at the expense of biodiversity.
In the study published in May 2019, researchers from the University of Göttingen argue that agrobiodiversity should be kept high in order to safeguard ecosystem services, but also emphasize the importance of nature conservation areas. At the same time, however, agricultural production should not be reduced too much. The results have been published in the journal People and Nature.
Man vs. nature?
"Many researchers argue that agricultural production should be intensified on existing land in order to increase yields and at the same time reduce agricultural pressure on the last remaining wilderness. This approach is mainly pursued in tropical countries," explains Dr. Ingo Grass from the Department of Agroecology at the University of Göttingen and lead author of the study. "However, biodiversity and agriculture are often closely intertwined and many species are also beneficial to farmers. In Europe's cultivated landscapes, many species worthy of protection are adapted to gently farmed habitats. These species are threatened by increasing agricultural intensification," adds Prof. Dr. Teja Tscharntke, head of the department.
The researchers describe that both concepts are justified and should be applied together. "Modern and sustainable agricultural landscapes require both land-saving and high-yield production areas, untouched habitats and extensively farmed areas. This combination not only enables the highest biodiversity, but also promotes ecosystem services such as pollination and biological pest control by insects and field birds. These are essential for sustainable agricultural production," says Grass.
To this end, landscape elements and various small habitats such as hedges, flower strips, rows of trees along streams and rivers, fallow land, etc. should be integrated into the agricultural areas. They are best linked to each other and to nature conservation areas. These structures can prevent the extinction of beneficial organisms and promote their spread. Mixed crops in the field are another way of increasing biodiversity.
Biodiversity brings economic benefits
The fact that increasing biodiversity also has economic potential is shown, for example, by a study in which the damage caused by leaf beetles (Oulema melanopus) to winter wheat near flowering strips was reduced by 40 percent, while the harvest volume increased by 10 percent. More stable crop yields with higher biodiversity have also been observed in coffee and cocoa plantations.
In some regions, however, where there is hardly any traditional agriculture left, such as in the Midwest of the USA, the promotion of near-natural habitats must be handled more sensitively, as unfortunately many introduced species have established themselves there and with them pests. It is interesting to note that native plants tend to harbor beneficial insects and invasive plants tend to harbor pests.
Species-rich agriculture is possible
In any case, the researchers conclude that nature reserves must be preserved at all costs. Many species cannot cope with agricultural areas and need natural habitats if they are to survive. Other species have adapted to human agriculture over thousands of years. In order to preserve the latter, the focus must not be purely on intensifying agriculture.
Sustainable food production therefore requires a network of nature reserves, near-natural areas, extensively farmed but also high-yield areas.
In collaboration with scientists, politicians, farmers and other stakeholders, landscapes could be designed that have the potential for both food security and high biodiversity. This proves once again that we already have the tools for sustainable food production in our hands!
