Nav: Home

Human activity affects interactions between plants and seed-dispersing birds

March 13, 2020

Research conducted in recent decades has shown how the destruction of forests brings about a decline in species diversity. A research group in Brazil led by scientists at São Paulo State University (UNESP) has now reported the findings of an investigation into how landscape changes caused by deforestation, habitat loss and fragmentation lead directly to the loss not only of species but also of their ecological interactions. The report is published in Biotropica and features on the journal's cover. The study was supported by São Paulo Research Foundation - FAPESP.

"In ecology, we know a lot about species-area relationships but little or almost nothing about the relationship between species interactions and loss of area. Our study used ecological networks to find out how seed dispersal interactions respond to loss of area and landscape fragmentation. Shrinkage of forest fragments leads to a loss of ecological interactions that are important to the functioning of forests and the maintenance of biodiversity," said Carine Emer, first author of the article, produced while she was a postdoctoral fellow in the Conservation Biology Laboratory (LABIC) of the Bioscience Institute (IB-UNESP) in Rio Claro, with funding from FAPESP.

The study was part of the project "Ecological consequences of defaunation in the Atlantic Rainforest", supported by FAPESP and led by Mauro Galetti, a professor at IB-UNESP.

The researchers compiled data from 16 studies of plant-frugivore interactions in different fragments of the Atlantic Rainforest biome selected to form a gradient of human disturbance inferred from the size of each forest remnant. They focused on the interactions between plants and seed-dispersing birds because these animals are considered essential to constant forest regeneration. They concluded that the smaller the forest fragment the smaller the number of species living there and the fewer the interactions that are able to persist.

Forests and interactions

The largest and best conserved forest in the study was in Intervales State Park in the south of São Paulo State, with 42,000 hectares. It had the highest species diversity (81 frugivores and 185 fruit-bearing plants) and the most plant-seed disperser interactions (1,100 or 3.65 per species).

At the opposite end of the gradient was a six-hectare fragment that has been regenerating for a little over eight years in Piracicaba, with a far smaller number of frugivorous birds (28 species) interacting with only a few fruit-bearing plant species (6). Thus 169 seed disperser interactions were recorded, corresponding to only 1.47 per species.

In the former area, one bird species dispersed the seeds of three to four plant species. In the latter, it dispersed no more than two.

"The first to disappear are the larger birds, which are essential to disperse plant species with large seeds. This loss isn't just numerical. It's also functional, directly influencing the forest regeneration process," Emer said. "In the medium to long term, plants with large seeds that lose their main dispersers tend to disappear from the landscape and become limited to larger, better conserved areas. The fragmented forest becomes poorer numerically and functionally. The only birds that remain are small species whose functional role is to disperse plant species with small seeds. In other words, we lose the ecological function of large seed dispersal. This can change our forests forever."

Another article published previously by the group, also with Emer as lead author, showed that interactions involving large species are lost in forest fragments of less than 10,000 hectares. It also highlighted the importance of small generalist bird species that disperse the small seeds of equally generalist plants, maintaining connectivity in a fragmented landscape. In other words, Emer noted, "the Atlantic Rainforest is currently connected by interactions involving generalist birds that disperse plant species adapted to disturbed environments."

Besides larger species, fragmentation also has an adverse effect on what are known as specific interactions. Thus a plant species dispersed by one or only a few bird species, for example, is more at risk of extinction than another species whose fruit is eaten by several different bird species.

The research line also includes a study published last year in the prestigious journal Science Advances, in which the group estimated in millions of years the loss to the evolutionary history of seed dispersal in the Atlantic Rainforest due to the disappearance of large birds.

"The Atlantic Rainforest has dwindled to only about 12% of its original area, and most of this is small forest fragments," Emer said. "There is great diversity of seed dispersal interactions in the fragments we analyzed, with most occurring in only one or two fragments. These interactions correspond to millions of years of evolution. Species with different evolutionary trajectories interact in the present and are increasingly restricted to a few areas. In sum, we've reached a threshold beyond which we can't afford any more losses. Each and every fragment of Atlantic Rainforest corresponds to millions of years of unique evolutionary history that must be conserved."
-end-
About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at http://www.fapesp.br/en and visit FAPESP news agency at http://www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

Fundação de Amparo à Pesquisa do Estado de São Paulo

Related Plant Species Articles:

Study: One-third of plant and animal species could be gone in 50 years
University of Arizona researchers studied recent extinctions from climate change to estimate the loss of plant and animal species by 2070.
Scientists challenge notion of binary sexuality with naming of new plant species
A collaborative team of scientists from the US and Australia has named a new plant species from the remote Outback.
Plant lineage points to different evolutionary playbook for temperate species
An ancient, cosmopolitan lineage of plants is shaking up scientists' understanding of how quickly species evolve in temperate ecosystems and why.
Native plant species may be at greater risk from climate change than non-natives
A study led by researchers at Indiana University's Environmental Resilience Institute has revealed that warming temperatures affect native and non-native flowering plants differently, which could change the look of local landscapes over time.
'Specialized' microbes within plant species promote diversity
A Yale-led research team conducted an experiment that suggests microbes can specialize within plant species, which can promote plant species diversity and increased seed dispersal.
New machine learning method predicts additions to global list of threatened plant species
A new method uses machine learning and open-access data to predict whether species are eligible for at-risk status on the IUCN Red List.
Bioactive novel compounds from endangered tropical plant species
A Japan-based research team led by Kanazawa University has isolated 17 secondary metabolites, including three novel compounds from the valuable endangered tropical plant species Alangium longiflorum.
Global study finds taller plant species taking over as mountains and the Arctic warm
A study by more than 100 global researchers, including Simon Fraser University biologist David Hik, is linking the effects of climate change to new and taller plant species in the Arctic and alpine tundra.
New plant species discovered in museum is probably extinct
A single non-photosynthetic plant specimen preserved in a Japanese natural history museum has been identified as a new species.
Plant virus alters competition between aphid species
In the world of plant-feeding insects, who shows up first to the party determines the overall success of the gathering; yet viruses can disrupt these intricate relationships, according to researchers at Penn State.
More Plant Species News and Plant Species Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.