Sustainable agriculture is essential to address global challenges such as climate
change and biodiversity loss. Hedgerows enhance aboveground biodiversity and provide
ecosystem services, but little is known about their impact on soil biota. Arbuscular
mycorrhizal (AM) fungi are one of the key components of belowground biodiversity.
We compared the diversity and composition of AM fungal communities at four farmland
sites located in Central Spain, where 132 soil samples in total were collected to
assess soil physical and chemical properties and the AM fungal communities. We compared
the richness (number of AM fungal taxa), taxonomic, functional, and phylogenetic diversity,
and structure of the AM fungal communities across three farmland habitat types, namely
hedgerows, woody crops (olive groves and vineyard), and herbaceous crops (barley,
sunflower, and wheat). Our results showed positive effects of hedgerows on most diversity
metrics. Almost 60% of the AM fungal taxa were shared among the three farmland habitat
types. Hedgerows increased AM fungal taxonomic richness (31%) and alpha diversity
(25%), and especially so compared to herbaceous crops (45% and 28%, respectively).
Hedgerows harbored elevated proportions of AM fungi with non-ruderal life-history
strategies. AM fungal communities were more similar between hedgerows and woody crops
than between hedgerows and adjacent herbaceous crops, possibly because of differences
in tillage and fertilization. Unexpectedly, hedgerows reduced phylogenetic diversity,
which might be related to more selective associations of AM fungi with woody plants
than with herbaceous crops. Overall, the results suggest that planting hedgerows contributes
to maintain belowground diversity. Thus, European farmers should plant more hedgerows
to attain the goals of the EU Biodiversity Strategy for 2030.
