Landscape‐level heterogeneity of agri‐environment measures improves habitat suitability for farmland birds

Abstract

Agri‐environment schemes (AESs), ecological focus areas (EFAs), and organic farming are the main tools of the common agricultural policy (CAP) to counteract the dramatic decline of farmland biodiversity in Europe. However, their effectiveness is repeatedly doubted because it seems to vary when measured at the field‐versus‐landscape level and to depend on the regional environmental and land‐use context. Understanding the heterogeneity of their effectiveness is thus crucial to developing management recommendations that maximize their efficacy. Using ensemble species distribution models and spatially explicit field‐level information on crops grown, farming practice (organic/conventional), and applied AES/EFA from the Integrated Administration and Control System, we investigated the contributions of five groups of measures (buffer areas, cover crops, extensive grassland management, fallow land, and organic farming) to habitat suitability for 15 farmland bird species in the Mulde River Basin, Germany. We used a multiscale approach to identify the scale of effect of the selected measures. Using simulated land‐use scenarios, we further examined how breeding habitat suitability would change if the measures were completely removed and if their adoption by farmers increased to meet conservation‐informed targets. Buffer areas, fallow land, and extensive grassland were beneficial measures for most species, but cover crops and organic farming had contrasting effects across species. While different measures acted at different spatial scales, our results highlight the importance of land‐use management at the landscape level—at which most measures had the strongest effect. We found that the current level of adoption of the measures delivers only modest gains in breeding habitat suitability. However, habitat suitability improved for the majority of species when the implementation of the measures was increased, suggesting that they could be effective conservation tools if higher adoption levels were reached. The heterogeneity of responses across species and spatial scales indicated that a mix of different measures, applied widely across the agricultural landscape, would likely maximize the benefits for biodiversity. This can only be achieved if the measures in the future CAP will be cooperatively designed in a regionally targeted way to improve their attractiveness for farmers and widen their uptake.

A cross-regional analysis of red-backed shrike responses to agri-environmental schemes in Europe

“…As we focused on grassland-based AES, we excluded grid cells with less than 1 ha of permanent grassland, which is the approximate territory size of the species (Brambilla et al 2009). The Catalan dataset (Roilo 2023) was additionally filtered to remove grid cells at elevations below 200 m a.s.l. and above 2000 m a.s.l., which are outside the altitudinal range limits of the red-backed shrike in Catalonia (Rodríguez-Franch et al, 2021).…”

“…We collated environmental variables known to influence the red-backed shrike distribution (Brambilla et al 2009, Roilo et al 2023. For each 1 km grid cell, we extracted the mean elevation (m; ELEVATION) from the Copernicus EU-DEM v1.1 and the maximum temperature ( • C, TMAX) and the sum of mean monthly precipitation (mm, PRECIP) between May and July, corresponding to the red-backed shrike breeding period, from the CHELSA Climatologies 1981-2010 V2.1 (Karger et al 2017(Karger et al , 2020.…”

Scale mismatches between predictor and response variables in species distribution modelling: A review of practices for appropriate grain selection

“…Therefore, they implicitly assume the existence of a common ecological scale for all predictor variables. However, it has been shown that the ecological scale is variable-specific since species often respond to different environmental variables at different spatial scales and sometimes even respond differently to a single environmental variable at multiple grains (Leitão et al, 2010; Lecours et al, 2020; Miguet et al, 2016; Roilo et al, 2022). However, despite theoretical concepts and extensive empirical evidence that species respond to their environment at different spatial grains (e.g.…”

Archetypes in support of tailoring land-use policies

“…For example, the limited effectiveness of agri-environment schemes (Batary et al 2015) can be attributed to the pronounced variability and nonlinearity in relationships between agriculture and farmland biodiversity, e.g. in protecting farmland birds (Whittingham et al 2007, Concepcion et al 2020, Roilo et al 2023. Therefore, land-use policies that are tailored to fit the characteristics of specific land systems are more effective than homogeneously implemented measures (Young 2013, Nolte et al 2017).…”