Environmental context

The Upper Paranapanema Basin contains significant remnants of Atlantic Forest alongside degraded agricultural areas experiencing erosion, water stress, and biodiversity decline.

Located at the edges of the Atlantic Forest and the Cerrado, the basin supports high biodiversity and plays a critical role in water regulation and landscape connectivity.

Over recent decades agricultural expansion and intensification, and expansion of irrigation have placed growing pressure on soils, rivers, ecosystems, and rural livelihoods.

These overlapping environmental and socio-economic pressures make the basin both high risk and high opportunity.

Targeted restoration and improved land-use management could position the Upper Paranapanema Basin as a model for integrating agricultural production, water security, and nature recovery at scale.

The Upper Paranapanema Basin is home to a wide range of Atlantic Forest plants and animals. This reflects its position within the Serra de Paranapiacaba forest landscape and the mix of habitats found across the basin, including large areas of forest, river corridors, and transition-zone environments.

Key species groups include:

Large and medium-sized mammals

The region supports forest-dependent mammals typically found in well-preserved Atlantic Forest landscapes. This includes wide-ranging and threatened species such as jaguars, pumas, South American tapirs, bush dogs and southern muriquis. These animals rely on large areas of connected habitat and are strong indicators of overall ecosystem health.

Birds

Bird life in the basin is highly diverse, with species associated with intact forests, river edges, and transition habitats. Many Atlantic Forest bird species are sensitive to habitat condition, making them useful indicators of ecosystem health and the success of restoration efforts.

Amphibians and other water-dependent species

Streams, wetlands, and riparian forests support amphibians and other species that depend on clean, well-regulated water. The presence of rare and range-restricted amphibians highlights the importance of headwaters and streamside habitats for conservation.

Plants and vegetation

The region contains areas with flora and fauna characteristic of the Atlantic Forest, enclaves with Cerrado affinities, and unique environments such as riparian forests, grasslands, and altitude-associated ecosystems. This variety of plant communities creates a diverse set of habitats that supports high species richness across the basin.

Biodiversity in the Upper Paranapanema Basin underpins a set of high-value environmental attributes that are critical at both basin and state scales.

Key environmental values include:

Strategic water sources
The basin contains important headwaters and spring systems that contribute to regional water supply, making forest protection directly relevant to water security.

Landscape connectivity
Large forest blocks, riparian corridors, and remaining forest fragments collectively support ecological connectivity across the landscape, enabling species movement and genetic exchange.

Soil stability and catchment protection
Native vegetation plays a major role in stabilising soils, reducing erosion, and limiting sedimentation in rivers, particularly important in an agriculturally intensive basin.

Ecological resilience
The coexistence of multiple habitat types increases the basin’s ability to absorb and recover from environmental stressors such as drought, floods, and land-use change.

The species and environmental features of the Upper Paranapanema Basin provide a wide range of ecosystem services that support farming, communities, and downstream water users. The following services have been classified using the Millennium Ecosystem Assessment framework for ecosystem services.

Provisioning services

Provisioning services are tangible products or resources that people can obtain directly from nature including:

Freshwater supply for households, irrigation, and industry, drawn from rivers, springs, and aquifers maintained by forests and headwaters
Food production including crops and livestock supported by fertile soils and favorable climate
Fish and aquatic resources from rivers and reservoirs throughout the basin
Timber and fuelwood from both native Atlantic Forest remnants and planted forests
Medicinal plants and genetic resources from the region's rich biodiversity
Fiber and fodder for livestock and various agricultural uses

Regulating services

Regulating services deliver benefits obtained from the regulation of ecosystem processes:

Water purification through natural filtration, nutrient uptake by vegetation, and buffering of pollutants before they reach waterways
Water flow regulation including groundwater recharge, maintenance of river flows during dry periods, and buffering of seasonal variability
Flood regulation through water retention in forests, wetlands, and soils, reducing peak flows and protecting downstream communities
Erosion control and sediment retention by vegetation and root systems, reducing damage to rivers, reservoirs, and infrastructure
Pollination by native insects and other animals, supporting both wild plant reproduction and agricultural productivity
Pest and disease regulation through natural predators and ecosystem balance, reducing agricultural losses
Climate regulation at local and regional scales, moderating temperature and moisture extremes
Carbon sequestration and storage, especially in mature Atlantic Forest vegetation and soils

Cultural services

Cultural services provide non-material benefits that contribute to human wellbeing and quality of life:

Recreation and ecotourism opportunities in forests, rivers, and reservoirs, supporting local economies
Aesthetic and spiritual values derived from natural landscapes, waterfalls, and forest environments
Scientific research and environmental education, improving understanding and management of natural systems
Cultural heritage and regional identity linked to forests, rivers, and traditional land use practices
Sense of place connecting communities to their landscape and history

Supporting services

Supporting services are foundational ecological processes that underpin all other ecosystem services:

Nutrient cycling through decomposition and biological processes, which underpin long-term land productivity
Soil formation and maintenance through weathering, organic matter accumulation, and biological activity
Primary production by plants, converting solar energy into biomass that supports all food webs
Habitat provision for native species and pollinators, supporting biodiversity and ecosystem balance
Landscape connectivity allowing species to move and ecosystems to function over time

Native vegetation in the basin ranges from large, continuous forest areas, such as the Serra de Paranapiacaba ecological continuum, the largest remaining Atlantic Forest block in Brazil, to highly fragmented landscapes dominated by small forest patches.

Despite their size and isolation, these fragments retain a significant proportion of the region’s original biodiversity, demonstrating their continued ecological value.

Land use, ecosystem condition, and environmental pressures vary markedly across the region, creating a mosaic of conserved and degraded areas with different risks and restoration needs.

This reflects long-term land use change and uneven conservation outcomes across municipalities, resulting in extremes of preservation and degradation within the same basin.

Recovery of Native Vegetation in Permanent Preservation Areas is a priority in the Government's 2025-2028 National Native Vegetation Recovery Plan (Planaveg).

The Upper Paranapanema is on the interface of the Atlantic Forest and the Cerrado. This transition zone supports species from multiple biomes which increases biodiversity, but also heightens species sensitivity to habitat loss and fragmentation.

Research shows that species respond differently to habitat loss depending on their position within geographic ranges. This indicates that conservation and restoration in transition regions can be particularly important for maintaining populations at range edges.

Permanent Preservation Areas (PPAs) are a central mechanism in Brazilian environmental law for protecting water resources, soils, biodiversity, and ecological connectivity on private land. In Southwestern São Paulo, a large share of these areas—especially along rivers and streams—are currently degraded and out of legal compliance, creating significant environmental liabilities for rural properties.

Approximately 155,000 hectares of riparian PPAs exist in the region, and nearly half are degraded. Large rural properties dominate the landscape and therefore hold most of the total area of PPAs requiring restoration. However, smaller properties show a higher proportion of degradation, meaning they are often less compliant despite having less land overall. This imbalance has important implications for policy design, as compliance costs fall unevenly across landholders.

Restoring PPAs is critical not only for legal compliance but for water security and landscape connectivity. Riparian PPAs link small forest fragments to major forest blocks, including the Serra de Paranapiacaba ecological continuum, and play a key role in maintaining water quality and regulating flows in a highly farmed landscape. Yet restoration costs are substantial, estimated at USD 76–100 million across the study area. Without financial incentives, payments for ecosystem services, or lower-cost restoration approaches (such as agroforestry and natural regeneration), many landholders (particularly smallholders) are unlikely to be able to meet their legal obligations.

Large properties account for 62% of the total analyzed area registered in the CAR, while medium-sized properties represent 15%, small properties 17%, and micro-properties only 6% of the total area.
Southwestern São Paulo contains approximately 155,065 hectares of Permanent Preservation Areas (APPs), of which about 47% are degraded. The results of the modeled scenarios vary depending on the assumptions regarding the size of properties without CAR registration; however, in all scenarios, more than 40% of APP areas require restoration.
Large properties hold the largest share of APP-related environmental liabilities. However, although small properties (less than two fiscal modules) have a smaller absolute area of APP to be restored, they show a proportionally higher amount of degraded areas.
Estimated restoration cost: USD 76–100 million (≈ USD 2,000/ha)

Despite its ecological importance, biodiversity in the basin remains incompletely documented. The rediscovery of the rare amphibian Phrynomedusa appendiculata in Capão Bonito after more than 40 years highlights substantial gaps in species inventories and long-term monitoring.

This finding enabled new ecological, acoustic, morphological, and phylogenetic data to be collected. It also suggests that additional species of conservation concern may remain undocumented.

There is a historical scarcity of data on much of the region’s biota. Numerous taxonomic groups have few published records, few systematic inventories, and lack long-term studies. This situation reinforces the importance of recent research efforts in the region and highlights the need to expand fieldwork and train specialists dedicated to local biodiversity.

UFSCar has a range of initiatives to document species richness in the region including installing recording devices at various locations and using machine learning to rapidly identify species.

Scientific evidence indicates that climate change is altering rainfall patterns in the Alto Paranapanema Basin, with implications for water resources, agriculture, ecosystems, and infrastructure. Observed and modelled changes include shifts in the timing and amount of rainfall.

These climatic shifts matter because water availability and variability are central to the basin’s socio-ecological systems, influencing crop water demand, erosion risk, species habitats, and hydrological function.

Analysis focused on the Alto Paranapanema Basin finds temporal shifts in rainfall patterns, including a reduction in rainfall during the wet season of up to 40% compared to historical averages. These changes point to a more variable and potentially less predictable rainfall regime, with implications for water storage, agricultural timing, and ecosystem water balance.

Changes in land use and land cover in the Upper Paranapanema Basin, particularly the expansion and intensification of agriculture, have led to a sharp increase in soil erosion, sediment production, and sediment export to water bodies.

Between 1987 and 2017, sediment production more than doubled and sediment export increased substantially, reflecting the conversion of pasturelands to more intensive agricultural systems and the expansion of farming into areas with higher erosion susceptibility.

Modelling results indicate that restoring riparian Permanent Preservation Areas (PPAs) and adopting conservation practices such as terracing and no-tillage can significantly reduce both sediment production and sediment export, especially when these strategies are combined.

Sediment production increased from 38.86 t ha⁻¹ year⁻¹ in 1987 to 91.80 t ha⁻¹ year⁻¹ in 2017, an increase of 136.2 percent

Sediment export increased from approximately 1.37 t ha⁻¹ year⁻¹ in 1987 to 4.1 t ha⁻¹ year⁻¹ in 2017

Restoration of PPAs alone reduced average sediment production to 42.69 t ha⁻¹ year⁻¹, a reduction of more than 50 percent

Conservation practices alone reduced sediment production to 11.42 t ha⁻¹ year⁻¹, a reduction of 87.6 percent compared to current conditions

Combined PPA restoration and conservation practices reduced sediment production to 10.81 t/ha/year

Sediment export under PPA restoration decreased to 1.66 t/ha/year, a reduction of approximately 59.5 percent

Combined PPA restoration and conservation practices reduced sediment export to 0.378 t/ha/year, corresponding to a reduction of approximately 90.8 percent

Environmental status

A unique and threatened environment

Current situation

Native vegetation

Species present

Environmental values

Ecosystem services

Research insights

Forest cover and fragmentation

Biome transition region

Compliance with environmental laws

Understanding species richness

Impacts of a changing climate

Sediment production and erosion