Even Natura 2000 cannot compensate for the negative effects of urbanization

In the past 20 years, the number of habitats of the Lyme butterfly in Poland has decreased twice, especially outside Natura 2000 areas. However, including these insects with the status of protected species does not guarantee an improvement of the situation. The biggest culprit is urbanization pressure – Poles agreed.

All over the world we are dealing with progressive degradation of habitats and decline in biodiversity. This is especially true in urban areas that are highly exposed to anthropogenic factors. To mitigate this effect somewhat, protected areas are being established, such as the Natura 2000 network, which now covers 18.5% of the country. land area of ​​the European Union.

dr. Joanna Kajzer-Bonk and Prof. Piotr Nowicki from the Faculty of Biology at Jagiellonian University decided to investigate whether the fact that the given habitats belong to the Natura 2000 site influences the rate of loss and the negative changes in the population living there. Their research, the results of which were published in the journal “Ecological Indicators” (https://doi.org/10.1016/j.ecolind.2021.1108518), was based on three species of Polish moths from the Lyme family: Nausitous Blue (Phengaris nausithous), Telejus Blue (P. teleius) and alconia blue (P. alcone).

“In light of the sixth world’s extinction and the climate crisis, protecting natural and semi-natural ecosystems is one of the most pressing needs in the world,” the authors point out on the pages of Ecological Indicators. of the main goals of humanity.

However, it is uncertain whether the existing forms of protected areas fulfill their function. Previous studies have shown that in the case of flying insects or the prevention of biological invasions, the effectiveness of such protection is insufficient. Does it depend on the taxonomic group of organisms to be protected or on the size of nearby human populations? How strong is the impact on the effectiveness of Natura 2000 activities from the continuously growing pressure of urbanization?

Researchers at Jagiellonian University recall that more than half of the world’s population lives in cities. Urban spaces are specific heat islands: they reflect, absorb and retain thermal energy, leading to permanent changes in environmental conditions. This effect is exacerbated by pollution and chaotic settlements.

Expansion of human settlements also causes fragmentation or even complete loss of habitats for many plant and animal populations. Stopping this trend should be a priority.

“Semi-natural grasslands appear to be one of the ecosystems most in need of protection in most urbanized areas. They are one of the most abundant ecosystems, covering up to 40% of the global land area, but at the same time severely degraded by human They are constantly threatened by further fragmentation and habitat loss, fertilization, mismanagement, climate change and biological invasions. PAP’s comment)”.

Because long-term monitoring of all components of biodiversity is too expensive and time-consuming, the authors focused on monitoring the so-called indicator species. These are organisms that respond quickly to environmental disturbances and signal emerging changes across a broad spectrum of biodiversity.

Such species can be butterflies of the genus Phengaris. They are protected on the territory of the EU and their presence proves the high natural values ​​of the pastures they inhabit.

“The aim of our study was to assess changes in the populations of Phengaris butterflies and their grassland habitats in and outside Natura 2000 areas” – the study authors write. They conducted their observations in a large pasture complex in the Vistula Valley on the outskirts of the city of Krakow. In the last century this area has grown from less than 7 km2 to 85 thousand. inhabitants, up to 327 km2 of the 781 thousand. Residents.

“Because of such strong anthropogenic pressures, we hypothesized that the rate of decline in habitat number, habitat and population size was similar regardless of previous location, but stronger outside Natura 2000 sites,” they add.

It turned out they were right. Within 20 years, the number of habitats of the studied butterflies has decreased twice: from 70 to 33 in the telejus and nausitous blue tit and from 18 to 9 in the alcona blue tit. The total area of ​​these habitats decreased by 13% respectively. and 21 percent

Scientists have found that habitat loss is mainly due to the disappearance of small and medium sized pieces. Before the creation of Natura 2000, this negative trend was the same regardless of habitat size and location; over time, the situation improved inside and outside protected areas deteriorated. However, this improvement only applies to large and medium patches, the small ones will still be lost.

When it comes to population size, the blue tears tested after the construction of Natura 2000 sites no longer show a negative downward trend. Outside the protected areas, however, the abundance of all three species continues to decrease locally.

“Our study revealed negative trends in both the number of habitats and their area available for the three butterfly species studied, Kraków biologists point out. Within them, the conservation regime has not prevented the disappearance of small pieces: they no longer exist anywhere.” Our findings therefore indicate that a form of protection such as Natura 2000 is effective in preserving medium to large habitats, but not small areas.

The status of protected species alone is therefore not sufficient to prevent their disappearance, the authors conclude. On the other hand, they add, it seems that the local populations within the Natura 2000 network are more stable and are spared the dominant negative population trends.

In the summary of the publication, the scientists emphasize that since the high proportion of greenery in urban landscapes can reduce the negative effects of the continued growth of cities, protecting urban meadows would have a doubly positive effect on the species living there. Firstly, it would stabilize the local climate and secondly, it would support the protection of not only endangered species but also the whole spectrum of biodiversity. Meanwhile, urban pastures are usually treated as an insignificant or insignificant landscape feature (unlike forest areas, for example) and destroyed without prior assessment of biodiversity.

The authors cite the results of previous studies showing that good land use planning conducive to dense development and protection of fragments of vegetation unaffected by human activity is a reasonable solution to reduce the effect of urban heat islands, and that about. Covering green spaces could neutralize the thermal effect of buildings and stabilize the temperature in cities. Such an approach would have other benefits in addition to preventing habitat loss and fragmentation. Including it would slow the spread of invasive species, reduce loss of species richness and abundance, facilitate water storage and air filtration, accelerate soil formation and pollination, and mitigate the effects of natural disasters.

“Preserving natural areas in cities is also critical to human well-being: improving mental health, cognition, pregnancy, reducing the risk of cardiovascular disease, type II diabetes and overall mortality. Green spaces can also play an important role. educational role in raising society’s awareness of the importance of urban biodiversity for human health and quality of life, and the perception of biodiversity as a value in itself,” the researchers conclude.

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