Grassland winners and arable land losers: The effects of post-totalitarian land use changes on long-term population trends of farmland birds

Highlights

• Population changes of farmland birds were related to gradients in their habitat use.

• Grassland species increased as arable land was converted to grassland.

• Arable land species declined as habitat was lost.

• Shrub encroachment did not have detectable effects on bird populations.

• These patterns may be typical for post-totalitarian agricultural transition.

Abstract

Biodiversity loss is an ongoing problem of European farmland and recent studies show that causes of this loss may vary among regions. At the same time, Eastern European post-totalitarian countries hold key part of farmland biodiversity within Europe but drivers of its changes remain poorly known due to lack of studies based on long-term data from this region. To fill this gap in our knowledge, we investigate how the post-totalitarian transformation of agricultural management, resulting in widespread land abandonment, affected land cover composition and, in turn, long-term changes of farmland bird populations in an Eastern European former communist country, the Czech Republic. Besides intensification in the most productive areas, we hypothesized that two scenarios might occur: (i) loss of farmland area resulting from its transformation to forests, successional habitats or built areas, (ii) conversion of highly energy-demanding arable land to extensively managed grassland. CORINE land cover data supported the second scenario with a massive gain of grassland area at the expense of arable land, while changes in areas of forest and successional habitats were only slight. This land cover change corresponded well with population increase of grassland birds and population decline of arable land birds, whereas mean population change of species associated with shrub and trees habitat was close to zero. These patterns are quite unique within biodiversity studies reporting declines of grassland bird species in North America and Western Europe, or shrub encroachment accompanied with increasing abundance of shrub-dwelling species in Southern Europe and South Africa. We suggest that the results found in the Czech Republic may also hold in other post-totalitarian Eastern European countries. Based on our findings, we recommend that the agri-environmental schemes applied in the Czech Republic, which focused mainly on grasslands and were only minimally represented on arable land, should now target on halting continuous decline of biodiversity on arable land.

Introduction

Despite considerable effort to shift the agricultural management from production to environmental friendly farming (Batáry et al., 2015), agriculture remains among the most important factors causing deterioration of European biodiversity (Butler et al., 2007). Its pervasive negative impacts are well mirrored in population trends of farmland birds (Reif, 2013, Voſíšek et al., 2010) which indicate health of entire farmland ecosystem (Gregory et al., 2005). At the same time, current commitments of EU agricultural politics are unambitious, but provide space for flexibility at the national level (Chiron et al., 2013, Pe⿿er et al., 2014). From this perspective, it is important to recognize regional-specific drivers of farmland bird populations in Europe (Báldi and Batáry, 2011). In this respect, Eastern European countries are particularly important because they are strongholds of farmland biodiversity but our knowledge about its determinants remains poor in this region (Sutcliffe et al., 2015).

One of the most profound agricultural changes in Eastern European countries was the transition from practices conducted under totalitarian government to production of food within competitive free market economy which took place in 1990s (Sarris, 1999). Since the practices under totalitarian economy were both labour and energy intensive but largely inefficient, opening the economy resulted in a steep drop in agricultural intensity expressed as per hectare consumption of pesticides and fertilizers, as well as in abandonment of less productive areas (Sutcliffe et al., 2015, Tryjanowski et al., 2011). These agricultural changes were followed by recovery of bird populations in some regions (Gregory et al., 2005), but this pattern was only weak and limited over time elsewhere (Reif et al., 2011). Consequences of this transformation are still relevant to present day agricultural practices and thus potentially important as drivers of farmland bird populations (Kamp et al., 2011, KoleĿek et al., 2015, Sanderson et al., 2013).

The Czech Republic is an Eastern European former communist country. The changes described above were particularly strong there due to prevalence of very large farms managed as state holdings thus being largely inefficient and poorly competitive after socioeconomic transformation (SkleniĿka et al., 2014). This situation contrasts to, for example, Poland, where privately held small farms were always the key part of agricultural sector even during the time of totality (Baſski, 2011). Surprisingly, decline of farmland birds did not reverse after 1990 in the Czech Republic suggesting the existence of some other drivers than agricultural intensification (Reif et al., 2008). In this respect, change in areas of major land cover types is among the most promising candidates which could result in simple reduction of the amount of habitat available for farmland bird species.

To elucidate this issue, we focused on changes in farmland bird populations and land cover in the Czech Republic from the end of 1980s to 2010. We might expect that after 1990, market forces lead to more efficient, intensive use of farmland in the most productive areas where arable land cultivation pays. In less productive agricultural areas, we hypothesize that two alternative scenarios of land cover changes could take place after 1990 as a consequence of agricultural transition. First, farmland could be abandoned and converted to other kinds of land uses including forestry, building development or remained unused and thus exposed to secondary succession towards scrub and trees followed by forest development, which is the terminal successional stage in this climatic zone (Neuhäuslova̿, 2001). The first scenario was frequently reported from the Mediterranean region (Clavero et al., 2011, Laiolo et al., 2004, Sirami et al., 2008). It was also claimed from the Czech Republic (Reif et al., 2008, Reif et al., 2013), but without tests on empirical data. Second, farmland may be not completely abandoned by agricultural cultivation, but the agricultural practices would change from highly energy-demanding croplands, such as cereals, to less demanding grasslands managed as pastures or meadows. Some indications for this scenario exist from the Czech Republic based, for example, on data about uptake of grassland-based agri-environmental schemes (Kováſ and Víta, 2009). However, a quantitative analysis of land cover changes at the country level that would either confirm, or reject this scenario is still lacking. This analysis is the first aim of this study.

In respect to farmland bird population changes, the first scenario should result in decline of species associated with open habitats (arable land or grassland) and increase of species breeding in closed habitats (shrub and trees). Under the second scenario, by contrast, we expect decline of species associated with arable land and population increase of grassland species. Although one could argue that these two habitats are occupied by a common set of farmland bird species, Teillard et al. (2014) have recently shown that grassland and arable land host largely different sets of species responding sensitively to changes of the extent of their preferred habitat. The second aim of this study is to test these two alternatives using data on farmland bird population changes and habitat use collected within large-scale breeding bird monitoring schemes in the Czech Republic.