The Effect of Subsidies on Woody Plant Encroachment

A new study by Agroscope shows that despite higher subsidies, bushes continue to spread on alpine meadows.

Woody plant encroachment on Swiss summer farm pastures leads to loss of grassland and of the culturally typical landscape. It is the result of land abandonment and changes in the type and intensity of agricultural activities. Woody plant encroachment on Swiss summer farm pastures is dominated by Green Alder (Alnus viridis), which is responsible for a decline in species diversity (Meier et al. 2021).

Three policy measures for reducing woody plant encroachment

To counter land abandonment and thus biodiversity loss, farmers are granted a range of subsidies in the form of direct payments. Three different subsidies were increased or introduced for the first time in 2014:

1. Livestock subsidies per livestock unit were increased.
2. Result-based subsidies for ecological focus areas were introduced. These require the presence of non-woody indicator plant species in grasslands as well as landscape elements.
3. Landscape quality subsidies were introduced which compensate farmers for maintaining and enhancing regionally typical landscapes undisturbed by woody plant encroachment.

To date, however, there has been no empirical examination of how these measures affect woody plant encroachment and grassland conservation.

This study investigates how the three above-mentioned subsidies affect woody plant encroachment on summer farm pastures in Switzerland. To this end, we compiled a dataset linking farm-level data from summer farms in the Canton of Grisons with remote sensing data on woody plant encroachment.

Unintended effect of subsidies on grasslands

The empirical investigation suggests that increasing subsidies caused an average 2% loss of grasslands per farm through woody plant encroachment. This corresponds to an average of 4.7 ha grassland loss per farm within 10 years. Thus, subsidies can have unintended consequences. In this context, it is important to mention that the impact of subsidies on species richness, diversity of structural elements and income was not investigated.

Possible explanations

There are two main possible explanations for grassland loss observed in connection with subsidies:

1. The spatial distribution of livestock has changed. Ecological focus areas may have been excluded from grazing to protect the vulnerable species they host, with the unintended side-effect of increased woody plant encroachment. Because livestock is a key factor for controlling woody plant encroachment (Pauler et al. 2022), its exclusion can have negative consequences.
2. Subsidies may have led to a decrease in mulching on the newly established ecological focus areas. Mulching is considered to be the most effective and economical measure for preventing woody plant encroachment.

This combination of disincentives may have significantly encouraged the observed development. However, further research is needed to clarify these mechanisms.

References

Meier E., Lüscher G., Buholzer S., Herzog F., Indermaur A., Riedel S., Winizki J., Hofer G., Knop E. 2021, Zustand der Biodiversität in der Schweizer Agrarlandschaft: Zustandsbericht ALL-EMA 2015−2019. Agroscope Science, 111, 2021.

Pauler, C. M., Zehnder, T., Staudinger, M., Lüscher, A., Kreuzer, M., Berard, J., & Schneider, M. K. (2022). Thinning the thickets: Foraging of hardy cattle, sheep and goats in green alder shrubs. Journal of Applied Ecology, 59(5), 1394-1405.