New methods of crop production and farmland birds: effects of plastic mulches on species richness and abundance
- Modern methods of crop production are regarded as one of the major factors moderating ecosystem processes in agricultural landscapes and may negatively affect farmland biodiversity. One method which is on the increase is mulching: the use of plastic foil to cover crops at sowing in order to promote early growth by reducing the negative effects of variable temperatures and to limit pesticide use. However, almost nothing is known of the role of mulching on farmland biodiversity.
- In this study, carried out in southern Poland in 2011, we investigated the impact of mulching with plastic foil on the number of species and abundance of farmland birds at two spatial scales.
- At the local scale, bird species number and abundance were lower in areas where foil was used than those in the control areas, both during the period when the foil was used and after it was removed from the crops. At the landscape scale, we found a significant negative relationship between the proportion of crops covered by foil and bird species richness and abundance. Farmland specialists, nonfarmland birds, ground nesters and above-ground nesting species were all negatively affected by foil mulching. Foil had a negative effect on potential resources for birds including adult butterflies and their larvae and weed species.
- Synthesis and applications. Our results provide the first evidence that the use of foil for mulching has negative effects on farmland bird populations, probably through the trophic cascade and habitat disturbance. Therefore, foil mulches must be considered as another factor contributing to the decline of farmland biodiversity. We suggest limiting the use of this method of vegetable production at the farm level. Decreasing the field size and converting some arable fields into grassland patches are proposed as mitigation measures in landscapes with high foil cover.