Background
The threats facing Ecuador’s Yasuní National Park are emblematic of those confronting the greater
western Amazon, one of the world’s last high-biodiversity wilderness areas. Notably, the country’s
second largest untapped oil reserves—called “ITT”—lie beneath an intact, remote section of the park.
The conservation significance of Yasuní may weigh heavily in upcoming state-level and international
decisions, including whether to develop the oil or invest in alternatives.
Methodology/Principal Findings
We conducted the first comprehensive synthesis of biodiversity data for Yasuní. Mapping amphibian,
bird, mammal, and plant distributions, we found eastern Ecuador and northern Peru to be the only
regions in South America where species richness centers for all four taxonomic groups overlap. This
quadruple richness center has only one viable strict protected area (IUCN levels I–IV): Yasuní. The
park covers just 14% of the quadruple richness center’s area, whereas active or proposed oil
concessions cover 79%. Using field inventory data, we compared Yasuní’s local (alpha) and landscape
(gamma) diversity to other sites, in the western Amazon and globally. These analyses further suggest
that Yasuní is among the most biodiverse places on Earth, with apparent world richness records for
amphibians, reptiles, bats, and trees. Yasuní also protects a considerable number of threatened species
and regional endemics.
Conclusions/Significance
Yasuní has outstanding global conservation significance due to its extraordinary biodiversity and
potential to sustain this biodiversity in the long term because of its 1) large size and wilderness
character, 2) intact large-vertebrate assemblage, 3) IUCN level-II protection status in a region lacking
other strict protected areas, and 4) likelihood of maintaining wet, rainforest conditions while
anticipated climate change-induced drought intensifies in the eastern Amazon. However, further oil
development in Yasuní jeopardizes its conservation values. These findings form the scientific basis for
policy recommendations, including stopping any new oil activities and road construction in Yasuní and
creating areas off-limits to large-scale development in adjacent northern Peru.
INTRODUCTION
The western Amazon is one of the world’s last high-biodiversity wilderness areas [1,2], a region of
extraordinary species richness across taxa [3–9] where large tracts of intact forests remain [10,11].
Indeed, it is still possible to walk continuously through mega-diverse forest from southern Peru to
southern Venezuela—a distance of ~2,000 kilometers—without crossing a single road. However,
numerous major threats confront the ecosystems of this region—including hydrocarbon and mining
projects, illegal logging, oil palm plantations, and large-scale transportation projects under the
umbrella of IIRSA (Initiative for the Integration of Regional Infrastructure in South America) [12]. For
example, oil and gas concessions now cover vast areas, even overlapping protected areas and titled
indigenous lands [13].
Yasuní National Park (Yasuní) in Ecuador is a major protected area within the western Amazon, yet it
faces threats emblematic of those facing the entire region. The park occupies a unique location at the
intersection of the Andes (< 100 km from the Andean foothills), the Amazon (near the western
phytogeographic limit of the Amazon Basin) [14], and the Equator (~1º S) (Figure 1A). Created in
1979, Yasuní covers approximately 9,820 km2 [15,16], and is surrounded by a 10 kilometer buffer zone
in all directions except to the east, where it meets the Ecuador-Peru border [17]. The park overlaps
ancestral Waorani (or Huaorani) territory, and is inhabited by at least two clans living in voluntary
isolation [16]. In 1989, Yasuní and much of the adjacent area that is now the Waorani Ethnic Reserve
were designated a UNESCO Man and the Biosphere Reserve [18]. Yasuní’s climate is characterized by
warm temperatures (averaging 24–27o C for all months), high rainfall (~3,200 mm annually), and high
relative humidity (averaging 80–94% throughout the year) [19]. Yasuní is within the “Core Amazon,”
a particularly wet region with high annual rainfall and no severe dry season [20]. The park’s
elevational range is small (from ~190 to ~400 m above sea level), but it is crossed by frequent ridges
of 25 to 70 meters [21,22]. Soils are mostly geologically young, fluvial sediments from erosion of the
Andes [22,23]. Yasuní protects a large tract of the Napo Moist Forests terrestrial ecoregion [24] and the Upper Amazon Piedmont freshwater ecoregion, which contains numerous headwater rivers of the
Amazon [25].
Several large-scale development projects exist or have been proposed within the park and its buffer
zone. Leased or proposed oil concessions cover the northern half of Yasuní, and four oil access roads
have already been built into the park or its buffer zone (Figure 1B). These roads have facilitated
colonization, deforestation, fragmentation, and overhunting of large fauna in the northwestern section
of the park [26–34] and illegal logging in the south and west [26,35]. Under IIRSA, the Napo River,
which borders the northern side of the park, may be dredged in order to become part of a major
transport route connecting Brazil’s port of Manaus with Ecuador’s Pacific coastal ports [36].
Moreover, large oil palm plantations have been established near the park, just north of the Napo River.
Despite these incursions, intact forest still covers the vast majority of Yasuní [32,34].
One of the most serious issues confronting Yasuní is that Ecuador’s second largest untapped oil fields
lie beneath the largely intact, northeastern section of the park (in the “ITT” Block, containing the
Ishpingo, Tambococha, and Tiputini oil fields; Figure 1B). The adjacent Block 31 contains additional
untapped reserves underlying Yasuní. Efforts by scientists and conservationists stopped a new oil-access
road into Block 31 planned by Brazil’s Petrobras, but Ecuador could re-auction this block at any
time. In response to strong opposition to oil drilling in Yasuní, the Government of Ecuador launched
the novel Yasuní-ITT Initiative in 2007. The Initiative offers to keep ITT oil permanently underground
and unexploited in exchange for financial compensation from the international community or from
carbon markets [37–38]. The Initiative’s primary goals are to respect the territory of indigenous
peoples, combat climate change by keeping ~410 M metric tons of CO2 out of the atmosphere, and
protect the park and its biodiversity.
The global conservation significance of Yasuní—a site often referred to anecdotally as one of the most
biodiverse places on Earth [e.g., 39,40]—may thus weigh heavily in upcoming state-level and
international decisions affecting the park. A preliminary assessment of Yasuní’s biodiversity was
conducted in 2004 in response to Petrobras’ planned road [27]. We build upon that effort here and
provide the first comprehensive synthesis of biodiversity data for Yasuní, assessing species richness,
endemism, and threatened species across various taxonomic groups. We compare our findings to those
from other regions, and discuss the global conservation significance of Yasuní by evaluating its
potential to sustain a high percentage of Amazonian biodiversity in the long term. We then assess the
threats to Yasuní’s conservation values from oil development. We close with policy recommendations
drawing upon these findings.
