Final report of the establishment of the biodiversity impact indicator and assessment of biodiversity change

The final report of the study on the establishment of the biodiversity impact indicator 'Bird population on agricultural land' is aimed at defining indicator values for 2020-2022 and at assessing the impact of the Lithuanian 2014-2020 Rural Development Programme (RDP) on biodiversity change in terms of farmland bird numbers and variety of species.

The main objectives of the study were: 1) to continue monitoring the abundance of breeding bird populations in the agricultural landscape of Lithuania; 2) to present the annual values of the Farmland Bird Indicator (FBI (KPPI in Lithuanian)) and the change curves of some periods, analyse the KPPI bird species population changes in their abundance; 3) to transfer the 2020-2022 KPPI values to Eurostat and OECD; and 4) to evaluate the impact of the Lithuanian 2014-2020 RDP and its measures and activities on rural bird populations in 2014-2022.

The evaluators have used bird point counting for the provision and evaluation of annual values of the common bird monitoring (ĮPGS is the acronym in Lithuanian) and FBI. This ensured methodological consistency and the compatibility of the results with the studies conducted since 1994.

For assessing the impacts of the Lithuanian 2014-2020 RDP and its measures on biodiversity change, selected quantitative and qualitative indicators were compared in 'experiment' areas (where RDP measures were implemented) and 'control' areas (similar areas where no RDP measures were implemented). When choosing the control areas, evaluators attempted to make their land cover as similar as possible to that of the experimental areas. Evaluators compared an equal number of 'experimental' and 'control' areas (points) and used GIS procedures to select the necessary number of closest ecologically similar monitoring sites (constant long-term bird recording sites/points) for the analysis. Methodologically, evaluators considered statistical information on local bird population numbers or pair density as indicators of quantitative assessment, and differences in species composition of communities as indicators of qualitative assessment.

The approach chosen for assessing the impacts of the Lithuanian 2014-2020 RDP on biodiversity (bird populations) was a compromise, as the 'experimental' and 'control' fields were defined after the implementation of RDP measures had begun. Ideally, experimental and control fields should be defined at least a year, and preferably two years, before the start of the intervention.

Evaluators have found that since 1994, the number of bird species whose local populations are decreasing in abundance has been increasing, and this trend appears to be progressing. Of the 14 FBI bird species, six have been declining since 1994, eight since 2000, ten since 2014 and 11 since 2020. Since 2000 (the reference year), in Lithuania, the populations of bird species common in the last century, such as the corncrake, lapwing, skylark, barn swallow, meadow pipit, whinchat, red-backed shrike, starling and goldfinch, have been decreasing. A little later, the population decline of other species (white stork and common whitethroat) began and is still ongoing.

During the analysed long-term period (2000-2022, 23 years), the FBI value decreased by 54.76 percentage points. The average annual rate of population decline for 14 FBI species (model species) is 2.4 percentage points.

In the medium-term period (2014-2022), the FBI value decreased by an average of 4.35 percentage points per year. In general, judging by the explained dynamics of FBI values (since 1994), biodiversity has been deteriorating faster in recent years.

Evaluators identified the agricultural activities that pose the greatest risk to birds. In total, 11 potentially hazardous agricultural factors threatening breeding bird populations in the agricultural landscape were analysed in more detail.

To clarify the impact of the 2014-2020 KPP measures related to the environment and climate change and the implementation of environmental directives on local bird populations and other biodiversity, evaluators analysed the monitoring data of the abundance of bird populations and 12 measures of the Lithuanian RDP 2014-2020 (as well as their sub-measures and activities). Measures applied to the use and management of grassland habitats and wetlands have recently had an exceptionally positive impact on bird populations. Natural perennial meadows (incredibly humid, wet and flooded; grazed meadows and wetlands) stand out for their positive impact and value on bird populations. Meanwhile, their overall qualitative impact is negligible. Only one of the evaluated measures, dedicated to the environmental protection of forest ecosystems, stood out in terms of its impact on birds. Its qualitative (as well as quantitative) impact on bird populations is high.

The overall quantitative impact of the analysed RDP measures on bird populations was positive and significant in the case of half (7 out of 14) of the FBI species. In case of the other three species (meadow pipit, starling and goldfinch), the quantitative effect was weakly positive or at least not negative. For the remaining four species (whinchat, whitethroat, red-backed shrike and yellow hammer), the effect was weakly negative or absent.