In University City eight kilometers from the São Paulo city center along the banks of the Pinheiros River live dozens of bird species. “The species diversity is greater than in some European countries,” commented biologist Elizabeth Höfling of the Biosciences Institute of the University of São Paulo (IB-USP) in her lecture, delivered on September 21, 2013 in São Paulo at the final meeting of the Biota-FAPESP Education Conference Cycle—an initiative of the Biota-FAPESP Program in partnership with Pesquisa FAPESP. The subject of the lecture was biological diversity in environments altered by human activity. Since 1984, Höfling and her team have identified 161 species of birds in the wooded areas of University City, including the Dusty-legged Guan (Penelope obscura), a typical Atlantic Forest bird measuring 70 centimeters high whose call resembles the clucking of hens.
Nearby Ibirapuera Park, the city’s largest, boasts an equally impressive diversity of species. In all, 142 species of birds have been identified, such as the Western Great Egret (Ardea alba), the noisy Southern Lapwing (Vanellus chilensis), the rare Blond-crested Woodpecker (Celeus flavescens) and the Red-crested Cardinal (Paroaria coronata). Someone taking a quiet stroll through the city’s parks might also see an Ingram’s squirrel (Sciurus ingrami), the Brazilian version of Northern hemisphere squirrels, or a Gray Brocket deer (Mazama gouazoubira). In a recent survey, a team from the Municipal Department of Green Areas and the Environment (SVMA) identified 433 species of wild animals scattered across the city, from tamarins to howler monkeys.
The diversity of birds and other animals in urban environments depends on certain factors, mainly the variety of plants that will provide food in the form of seeds and fruit, and branches and trunks for nest-building. In addition, air pollution and noise from cars can make life difficult for the animals in these environments. According to Höfling, the excessive noise of large cities can trigger loss of hearing, raise stress and change the behavior of certain species, and artificial illumination can impair day/night perception, which is essential for regulating an animal’s activities. As a result, as residents of São Paulo have already seen, thrushes—one of the species that has adapted to urban spaces—freely inhabiting residential areas begin to sing at three in the morning, annoying residents who would rather sleep and literally giving life to the saying about the city that never sleeps.
The Black Vulture (Coragyps atratus), another well-adapted species, can be easily found near Greater São Paulo’s two principal rivers, the Tietê and the Pinheiros. Although it is not always welcomed by urban residents, this species of vulture helps clean up the city by feeding on fish, rodents, birds and other animals decomposing along the riverbanks. In these areas, one might also catch sight of sparrows (Passer domesticus), Rock Pigeons (Columba livia) and a red-beaked bird known as the Common Waxbill (Estrilda astrild)—all of them exotic species but well-adapted to the city. “Insects such as bees, wasps, butterflies and moths, birds such as hummingbirds, and even mammals such as bats are vital to the reproduction of plants in cities because they act as pollinators,” Höfling pointed out.
One major problem for the survival of these urban animals is the fact that wooded areas are increasingly shrinking due to unplanned growth in cities, among other factors. In Brazil, 85% of the population now lives in urban areas. “Our development model and consumption pattern have created a growing demand for natural resources and endangered the remaining native areas in the state of São Paulo,” said biologist Roseli Buzanelli Torres of the Campinas Institute of Agronomy (IAC), in her presentation on plant diversity in landscapes altered by humans.
The Campinas Metropolitan Region, for example, which comprises 19 municipalities, is experiencing a critical situation, according to Torres, inasmuch as less than 6% of the native Atlantic Forest vegetation remains intact. “The remaining vegetation area covers less than 1% of the total area in the municipality of Hortolândia, near Campinas,” Torres said. “The same declining trend can be observed in cities like Nova Odessa, Santa Bárbara d’Oeste and Sumaré, each having less than 1% of its area covered by wooded remnants of Atlantic Forest.”
Torres coordinated a socioenvironmental analysis of the Anhumas River Basin in a densely populated area of Campinas, in partnership with the University of Campinas (Unicamp), the University of Brasília (UnB) and the Forestry Institute of São Paulo, as well as experts from the Campinas municipal government. On the basis of aerial photos and satellite images, they were able to observe an exponential expansion of urban areas into rural and native vegetation areas—which have been left considerably fragmented but still host a large diversity of tree species such as guaçatonga (Casearia sylvestris), pau-jacaré (Piptadenia gonoacantha) and marinheiro-do-brejo (Guarea macrophylla), among others. Torres also emphasized the importance of tree planting in cities as a tool for preserving biodiversity in isolated remnants of vegetation in the urban landscape.
“In the state of São Paulo,” said agronomist Luciano Martins Verdade of the Center for Nuclear Energy in Agriculture at USP, “most of the forest remnants and animal diversity can be found in agricultural landscapes, not in conservation units.” In his presentation on the diversity of animal species in agricultural regions, he showed that areas devoted to agriculture can host a wide variety of wild animals—mammals, fish, amphibians and birds—usually unappreciated, like the ones in cities and conservation units.
Some birds are already adapted to wooded areas near plantations, such as the Blue-fronted Parrot (Amazona aestiva), the Buff-necked Ibis (Theristicus caudatus) and the Whistling Heron (Syrigma sibilatrix). “It is estimated that up to 60% of the bird species that originated in these environments also live in altered agricultural landscapes,” Verdade said. In the few forests in inland São Paulo State, which features vast sugarcane and eucalyptus plantations, he himself has come across a cougar (Puma concolor), “an animal more and more commonly seen in environments altered by human activity.” According to Verdade, the Crab-eating Fox (Cerdocyon thous) is another species adapted to the agricultural landscape and can be seen relatively easily in the midst of sugarcane plantations.
The fact that wild animals live in agricultural areas raises a conflict between economic production and environmental conservation that can be reconciled, Verdade believes. “Looking at this conflict from the standpoint of conservation included in the dynamics of agricultural production is perhaps the best way for us to give agriculture a multifunctional mission, one that recognizes its productive nature and at the same time promotes environmental conservation,” he said. For now, agricultural interests are the predominant force, since Brazil is one of the world’s principal producers of agricultural commodities. To get a more accurate picture, the total land area devoted to agriculture occupies nearly one-third of the national territory, or about 260 million hectares; soybean plantations extend across 28 million hectares; and sugarcane plantations, linked to the production of ethanol, sugar and energy, account for nine million hectares. In the state of São Paulo, agricultural activity is a major reason for the state’s wealth and also for the decline in original areas of Atlantic Forest and Cerrado vegetation, which are now significantly fragmented.
“Knowing the distribution patterns and abundance of populations of wild animal species in agricultural landscapes will not suffice if we want to develop consistent strategies for conserving biological diversity,” Verdade warned. “How can we assess the impact of changes in land use on biodiversity?” When we don’t know what to do, he believes, the most appropriate course of action would be to strengthen the conceptual foundations to create a better understanding of the situation. Technological or methodological innovations, in turn, may be needed when we already know what to do in order to promote conservation of biodiversity in agricultural landscapes. And finally, governance—meaning articulation between public and private institutions—is essential for effective implementation of conservation proposals.
“Just knowing the biological patterns characteristic of each landscape contributes little to the process of governance. The fact is that these patterns are determined by epidemiological, human, evolutionary and other processes. So the diversity of patterns is determined by the complexity of the processes,” he said. “The most important thing for formulating conservation strategies would be, above all, to understand what creates the complexity of those processes.”
In cities, incentivizing tree planting could help strengthen conservation strategies by creating environments with mild temperatures that are more agreeable for both people and wild animals. “Trees with denser crowns retain up to 98% of solar radiation,” said Torres of the IAC. She pointed out that trees even help reduce the effects of a heavy rainfall. A tipu tree (Tipuana tipu) or a sibipiruna tree (Caesalpinia peltophoroides), for example, can retain up to 60% of the water in the first two hours of rainfall, thereby reducing flood intensity.