Chapter 15 - The decline of butterfly populations due to climate and land use change in Romania

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The widespread use of pesticides, changes in the structure of the landscape due to industrial and agricultural uses, and climate change have massively affected insect populations. The decline in insect biodiversity and biomass is documented in some countries in Europe, Asia, and North America. Romania, compared to Western and Central European countries, is considered to preserve a less altered nature and high biodiversity, being often given as a positive example in terms of conservation of natural and seminatural structures of the landscape. Unfortunately, the reality is different. The negative trends highlighted in Central European countries are reflected almost at the same intensity in Romania. During the communist era (1965–89), Romania reached the maximum percentage of land use for agricultural purposes. To increase production, intensive land use was associated with the application of impressive amounts of pesticides, the scale of which is unfortunately not officially known. Due to the collapse of the economy during the postcommunist period (1990–2000), nature had a short break which allowed it to recover. After 2000, agriculture has returned to an upward trend dominated increasingly by large landowners who in recent years have altered and destroyed the majority of the mosaic-type cultural landscape in Transylvania. At the same time, the vast deciduous and softwood forests of the Carpathians were strongly fragmented and reduced in area. Due to the global warming, the species of butterflies that emerge in spring show an obvious shift of flight periods toward March. On the other hand, species with a flight period until the beginning of autumn extend their flight period until the end of October or the beginning of November. In the period 1930–2019, the gap of the flight period toward the beginning of spring or before the end of autumn sums for some species 30 days. All this has led to a decline in butterfly populations. This paper presents for the first time the documented decline of butterflies in a Southeastern European country. Using the data regarding butterflies from the surroundings of Cluj from the period 1920–2019, we could show that 16 butterfly species have disappeared and 29 species have gone through a massive population decline. On the other hand, in the Red List of Romanian Lepidoptera, 25.11% species are considered endangered.