Assessing non-intended effects of farming practices on field margin vegetation with a functional approach

Abstract

To assess the unwanted side effects of farming practices on non-target plants, we used a nationwide survey of the vegetation of arable field margin strips. The vegetation was surveyed during two years (2013, 2014) in 430 field margins distributed over all agricultural regions of France. We used two complementary multivariate, trait-based approaches to examine how ten plant traits were related to ten environmental variables describing abiotic conditions, landscape factors, field margin management and in-field practices. Generalized additive mixed models were also developed to assess how the same environmental variables correlated with species richness, functional diversity and relative richness of agrotolerant versus hemerophobic species. Traits responded primarily to an environmental gradient of landscape diversity and field margin management. For instance, narrow field margin strips, frequent management and presence of a ditch favoured annual plants, small size at maturity and perennial plants, respectively. The second environmental gradient affecting plant traits was related to field size and intensity of in-field farming practices. On this gradient, fertilizer drift appeared to have a much stronger effect on plant trait composition of field margin strips than herbicide drift. The relationship between species richness, or functional diversity, and environment was consistent with the trait-based approach: the two former variables were negatively correlated with agriculture intensification (e.g. field size). However, this analysis also highlighted new covariates, such as a negative relationship between frequency of herbicide use and species richness. Some of the observed patterns seemed to be driven by differential responses of agrotolerant versus hemerophobic species, with the latter being more species-rich under organic than under conventional farming. Despite efforts to reduce nitrogen inputs since the 2000s, our results shows that N-fertilization still has significant nonintended effects on field margin vegetation. More generally, increasing the width of field margin strips, keeping or restoring semi-natural elements (ditches, hedges) in the field boundary, and lowering the number of management events may promote grassland plant species more typical of semi-natural habitats.

Agri‐environment schemes enhance pollinator richness and abundance but bumblebee reproduction depends on field size

“…We found the lowest species richness of insect‐pollinated plants in field edges with conventional management. This was probably because of the use of herbicides and inorganic fertilizers, which impact not only the field but also the grassy margin adjacent to it (Fried, Villers, & Porcher, 2018). In contrast, no herbicides are allowed in organic fields and flower strips, which is probably why we found three times higher plant species richness in both AES.…”

Effects of herbicides on non-target plant species diversity and the community composition of fallow fields in northern China

“…In this study, although atrazine and tribenuron-methyl both reduced the number of plant species, they did not significantly change the functional composition of the plant communities within three years. Previous studies have shown that fertilizer drift appeared to have a much stronger effect than herbicide drift on the plant trait composition in field margin strips 20 ; however, a significant interaction between herbicides and other agrochemicals shifted the functional structure of communities over the course of 11 years 50 . Although plant functional trait analysis could better reveal the value of non-food plant resources to food production and biodiversity in agroecosystems 4,51 , studies on the effects of herbicides on plant functional groups in agroecosystems are limited.…”

“…In aggregate, the herbicides altered the plant species composition and reduced plant community diversity by reducing the number of species in the fallow field. Although species richness is not necessarily the most suitable indicator of healthy non-crop habitats in adjacent farmlands because some species are known to respond positively to disturbances 20 , changes in the number of species will inevitably affect the plant interactions in a plant community.…”

“…In contrast, many studies have focused on the effect of herbicides on the biomass, reproduction, and progeny of individual plants [15][16][17][18] .While these studies revealed that herbicides damage the ecological adaptability of plants, a knowledge gap remains between the study of individual plants and the actual goal of plant community protection 19 . Fortunately, much attention has been paid to the effects of herbicides on the non-target wild plant community of non-crop habitats, especially field margins in agricultural landscapes [20][21][22] . Fallow fields, which are common non-crop habitats in Herbicide selection.…”

Promoting generalist predators of crop pests in alley cropping agroforestry fields: Farming system matters

“…minimalist management, maintaining bushes, mowing the vegetation, sowing plant mixtures). UVS width also varies from one alley cropping system to another and is expected to have an impact on the quality and quantity of habitats and trophic resources (Aavik and Liira, 2010;Fried et al, 2018). Ecological engineering of UVS is still in its infancy, and future research should assess how these management strategies affect biological control level in crop alleys.…”