How far back should we look? Long-term grassland changes to inform habitat restoration planning

Long-term time-series analyses are essential to avoid underestimating ecosystem loss and degradation and to prevent the shifting baseline syndrome when assessing habitat decline and setting restoration targets. Our aims were to (1) quantify historical area changes of semi-natural and transitional (degraded, regenerating, or intensive) grasslands in Hungary; (2) assess grassland continuity; and (3) evaluate grassland habitat loss across different historical reference points. For the analysis, we updated and supplemented the Habitat Trend Database of Hungary (5000 sample localities) with new field data collected in 2024, representing the past ten years of changes. The analysed database contains habitat data estimated for eight time points over the past 240 years. Our results show that grassland cover declined from 37.6% in the 18th century to 9.2% today, reaching its minimum extent (8.4%) in the 1980s. It is now increasing due to the expansion of transitional grasslands regenerating after the peak of cultivated area in the 1960s. Over the 240-year study period, the total loss of semi-natural grasslands accounted for 86.3%. 67% of Hungary's current semi-natural grasslands have remained continuous since the 18th century, while only 8.7% of the 18th-century semi-natural grasslands persist continuously to the present day. The average area of the studied Natura 2000 grassland habitats decreased by 38% since the 1980s, by 61% since the 1960s, and by 70% since the 1940s. We argue that if the original extent of habitat loss is not clearly documented and communicated, both the scientific community and society may gradually lose awareness of past ecosystem conditions.