Natural vegetation often It lacks many species that could be present but they are not. This occurs mainly in regions much affected by human activity .
A research published Today (02/04) in the journal Nature made an exhaustive survey of this situation in 119 regions around the world. The article accounts for what experts call Dark Diversity in English, which in Portuguese could be called “missing diversity”.
More than 200 researchers, members of the Darkdivnet international collaboration, participated in the study, investigating the presence or not of plants in 5,500 locations.
The research was coordinated by Professor Meelis Pärtel, from the Institute of Ecology and Earth Sciences at the University of Tartu in Estonia. And had the participation of Alessandra Fidelis and Mariana Dairel, among other Brazilians.
“In each place, local researchers recorded all plant species and identified the missing diversity, that is, the native species that could live there, but they were absent. This allowed us to understand the potential of plant diversity in place and also measure the impact of human activities on natural vegetation,” explains Fidelis, the São Paulo State University Institute (IB-UNESP).
According to the study, in regions with little human impact, ecosystems usually have more than one third of the potentially appropriate species. The absence of the other two thirds is due to natural factors, such as limited dispersion. However, in regions strongly impacted by anthropic activities, ecosystems contain only one in five appropriate species.
“Traditional biodiversity measures, such as simply counting the number of species present, do not detect this impact, because the natural variation of biodiversity between regions and ecosystems hides the true extension of human influence,” the study coordinators say.
Professor Meelis Pärtel says that the Darkdivnet collaboration began about seven years ago in 2018.
“We had introduced Dark Diversity’s theory and developed methods to study it, but to perform global comparisons, we needed a consistent sampling in many regions. It seemed an impossible mission, but many colleagues from different continents joined us,” he says.
Despite the difficulties arising from Covid-19 pandemic and global economic and political crises, the data have been collected over the years, even without central funding.
Fidelis joined the study since the beginning, when a small meeting about DarkDivnet was held at a congress of the International Association for Vegetation Science (IAVs) in Bozeman, United States, in 2018.
“From this, several researchers joined the initiative, applying the same methodology in various places of the world. Dr. Mariana Dairel, at the time my doctoral guidance, excited about the idea and assisted me in gathering the data. We decided to collect information in the region of Itirapina, in the state of São Paulo, where the ecological and experimental stations of itirapin are located. Native to Cerrado as anthropized areas, with planting of pines and eucalyptus, ”says the researcher.
He adds: “We know that the human impact has brought several consequences for ecosystems, affecting biodiversity. However, this study goes further: it shows how we are losing not only the species that were there before, but also the ones that could potentially be in the area, thus affecting natural regeneration.”
Ecological footprint
The level of anthropic disturbance in each region was measured using the ecological footprint indicator, which includes factors such as human population density, changes in land use (such as urbanization and agriculture) and infrastructure (roads and railways).
The study found that plant diversity in a place is negatively influenced by the level of the “ecological footprint”. The higher the index, the lower the diversity. The anthropic influence can extend to hundreds of kilometers around the point where it occurs.
“This result is alarming because it shows that human disturbances have a much broader impact than it was thought of, reaching even natural reserves. Pollution, deforestation, waste disposal, trampling and fires caused by humans can exclude plants from their habitats and prevent recolonization. We also found that the negative influence of human activity was less pronounced when at least one third of the region around remained intact, which reinforces the global goal of protecting 30% from terrestrial territory by 2030, ”says Professor Pärtel. And warns of the need to maintain and improve the health of ecosystems beyond natural reserves, using the concept of “missing diversity” as a practical tool for conservation and restoration activities.
The authors of the study attribute the impoverishment of vegetation to fragmentation, loss of connectivity, defaunation (loss of animal species, especially seed scatters), disorders such as fire and wood extraction, as well as eutrophization (pollution process that occurs when there is an increase in nutrients in water bodies, such as rivers, lakes and estuaries). The presence of at least 30% of the natural state landscape was associated with a mitigation of these effects.
Alessandra Fidelis received support from FAPESP through the project “How does the time of fire affect Cerrado’s vegetation?” and Mariana Dairel was awarded by Fapesp with a Doctoral bag.
The article “Global Impoveishment of Natural Vegetation Revealed by Dark Diversity” can be accessed here.
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This content was originally published in a study shows hidden impact of humans on nature around the world on CNN Brazil.
Source: CNN Brasil
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