Palm distribution patterns in the southwestern Brazilian Amazon: Impact of a large hydroelectric dam

Santos, Ednéia Araújo dos; Medeiros, Marcelo Brilhante de; Ferreira, Evandro José Linhares; Simon, Marcelo F.; Oliveira, Washington; Costa, Flávia R. C.

doi:10.1016/j.foreco.2020.118032

Cited by 14 publications

(8 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Development of riparian forest with species composition adapted to periodic flooding along reservoir margins may take decades or longer, or may never happen, due to the changed hydrology of the lentic environment compared to the lotic (Nilsson et al, 1997). Riparian vegetation surrounding lentic water may suffer stress from a higher water table, which could lead to floristic compositional changes and species mortality (Jin et al, 2019;dos Santos et al, 2020). Addition of newly created riparian zones around reservoirs and changes in flooding regime around reservoir areas can also lead to species invasions (Lesica and Miles, 1999;Nilsson and Berggren, 2000;Commander, 2013), further changing the composition of riparian vegetation in the region.…”

Section: Discussionmentioning

confidence: 99%

Cumulative Impacts of Land Cover Change and Dams on the Land–Water Interface of the Tocantins River

Swanson

Bohlman

2021

Front. Environ. Sci.

View full text Add to dashboard Cite

Riparian vegetation performs important ecosystems services, improving water quality, mitigating erosion, and maintaining regional plant and animal biodiversity. Regular annual flooding maintains riparian forests through an intermediate disturbance regime. In response, seasonally flooded vegetation has developed adaptations for seed dispersal and gas transfer to survive and reproduce while undergoing periods of flooding. In the Amazon, a dam building boom threatens the integrity of riparian vegetation by moving riparian corridors into dry-adapted ecosystems and reducing downstream flooding of riparian areas. Additionally, the region is undergoing intense development pressure resulting in the conversion of native riparian vegetation into agriculture. In this study, we measure how the installation of six large dams on the Tocantins River, coupled with land cover change from native forest and savanna to cattle pasture, has changed the land–water interface of this region. Using land cover data provided by MapBiomas, we quantified land cover change from 1985 to 2018 and measured changes in the riparian areas of the still free-flowing areas of the Tocantins River, riparian areas surrounding reservoirs, and in-stream vegetation dynamics. We found that deforestation in the riparian areas of the Tocantins River downstream of the dams is occurring at a higher rate than deforestation in the watershed. Additionally, reservoir filling resulted in creating hundreds of square kilometers of new riparian areas, pushing the riparian zone away from forest-dominated ecosystems into savanna-dominated areas. The quantity of in-stream vegetation throughout the study was dynamic and initially increased after damming before declining for the last decade of the study. Changes to native land cover in riparian areas of the Tocantins River threaten the integrity of ecosystem services provided by riparian vegetation and are likely to lead to further degradation of these areas.

show abstract

Section: Discussionmentioning

confidence: 99%

Cumulative Impacts of Land Cover Change and Dams on the Land–Water Interface of the Tocantins River

Swanson

Bohlman

2021

Front. Environ. Sci.

View full text Add to dashboard Cite

show abstract

“…For example, in some cases, areas affected by flooding at different levels were recognized by satellite data as living forests. Such areas, although still standing after flooding, experienced species loss, as well as changes in functional composition [ 17 , 20 ], which cannot be detected by remote sensing data alone. This is more challenging with medium resolution optical images such those from Landsat.…”

Section: Discussionmentioning

confidence: 99%

“…It has been shown that rare species are more seriously threatened by artificial flooding and deforestation [ 55 ], as well as habitat fragmentation associated with mega-dams in the Amazon [ 56 ]. Studies carried out in the area of the Jirau dam reported that populations of trees and palm species associated with várzea forests were the most seriously affected by the filling of the reservoir [ 19 , 20 ]. We found that 41 out of 326 morphospecies surveyed in five várzea plots were lost after the 2014 flood, indicating that populations of a considerable fraction of the regional species pool, particularly flooding-sensitive species that occur in low abundances, were severely affected.…”

Section: Discussionmentioning

confidence: 99%

“…Plot survey showed that composition and abundance of tree species were mainly determined by soil fertility and the distance from the nearest drainage, reflecting the influence of the riparian zone on the vegetation [ 19 ]. It also has been shown that 61% of palm species recorded in the study area occur within the area of direct influence predicted by the reservoir [ 20 ]. Environmental heterogeneity is a key factor for maintaining beta-diversity patterns among different vegetation types, with shallower water table during the rainy season representing a strong environmental filter for campinarana forest communities [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mega-dams and extreme rainfall: Disentangling the drivers of extensive impacts of a large flooding event on Amazon Forests

et al. 2021

View full text Add to dashboard Cite

Extreme weather events and the presence of mega-hydroelectric dams, when combined, present an emerging threat to natural habitats in the Amazon region. To understand the magnitude of these impacts, we used remote sensing data to assess forest loss in areas affected by the extreme 2014 flood in the entire Madeira River basin, the location of two mega-dams. In addition, forest plots (26 ha) were monitored between 2011 and 2015 (14,328 trees) in order to evaluate changes in tree mortality, aboveground biomass (AGB), species composition and community structure around the Jirau reservoir (distance between plots varies from 1 to 80 km). We showed that the mega-dams were the main driver of tree mortality in Madeira basin forests after the 2014 extreme flood. Forest loss in the areas surrounding the reservoirs was 56 km2 in Santo Antônio, 190 km2 in Jirau (7.4–9.2% of the forest cover before flooding), and 79.9% above that predicted in environmental impact assessments. We also show that climatic anomalies, albeit with much smaller impact than that created by the mega-dams, resulted in forest loss along different Madeira sub-basins not affected by dams (34–173 km2; 0.5–1.7%). The impact of flooding was greater in várzea and transitional forests, resulting in high rates of tree mortality (88–100%), AGB decrease (89–100%), and reduction of species richness (78–100%). Conversely, campinarana forests were more flood-tolerant with a slight decrease in species richness (6%) and similar AGB after flooding. Taking together satellite and field measurements, we estimate that the 2014 flood event in the Madeira basin resulted in 8.81–12.47 ∙ 106 tons of dead biomass. Environmental impact studies required for environmental licensing of mega-dams by governmental agencies should consider the increasing trend of climatic anomalies and the high vulnerability of different habitats to minimize the serious impacts of dams on Amazonian biodiversity and carbon stocks.

show abstract

“…Damming rivers floods large forest areas, reduces the flood pulse and changes water-table depth [6,7]. In addition to reducing flood pulses, damming reduces várzea forest, a type of seasonally-flooded forest with unique fauna [8][9][10][11][12][13] and flora [14,15]. Várzeas are flooded annually by nutrient-rich white-water rivers for 6 to 8 months and these highly-diverse areas connect habitats and play a key role in maintaining regional biodiversity due to their spatial and temporal complexities [16,17].…”

Section: Introductionmentioning

confidence: 99%

Impacts of an Amazonian hydroelectric dam on frog assemblages

et al. 2021

View full text Add to dashboard Cite

About 90% of the Amazon’s energy potential remains unexploited, with many large hydroelectric dams yet to be built, so it is important to understand how terrestrial vertebrates are affected by reservoir formation and habitat loss. We investigated the influence of the construction of the Santo Antônio Hydroelectric dam on the Madeira River in southwestern Amazonia on the structure of frog assemblages based on samples collected in two years before the dam flooded (pre-stage) and one (post1-stage) and four years (post2-stage) after its construction. We surveyed five 500-ha plot systems three times during each stage; in the pre-stage we sampled 19 plots in low-lying areas that would be flooded by the dam, (from now called flooded pre-stage plots) and 45 plots in terra-firme forest (from now called unflooded pre-stage plots). At the post1-stage we sampled the 45 unflooded plots and in the post2-stage we sampled the remaining 39 unflooded plots. We detected frogs by active visual and acoustic searches standardized by both time and sampling area. Few species recorded in the pre-stage flooded plots were not found in the pre-stage unflooded plots or in stages after flooding. However, the composition of frog assemblages based on relative densities in flooded pre-stage plots did not re-establish in plots on the new river margins. In unflooded areas, frog assemblages were distinct among the flooding stages with no tendency to return to the original assemblage compositions even four years after the dam was filled. For the areas that were not flooded, there was an increase in species richness in 82% of the plots between the surveys before dam construction and the first surveys after dam completion, and 65% between the pre-stage and surveys four years after dam completion. Lack of understanding by the controlling authorities of the long-term effects of landscape changes, such as water-table rises, means that studies covering appropriate periods post construction are not required in legislation, but the data from Santo Antônio indicate that changes due to dam construction are either long-term or difficult to distinguish from natural fluctuations. Future environmental-impact studies should follow strict BACI designs.

show abstract

Palm distribution patterns in the southwestern Brazilian Amazon: Impact of a large hydroelectric dam

Cited by 14 publications

References 44 publications

Cumulative Impacts of Land Cover Change and Dams on the Land–Water Interface of the Tocantins River

Cumulative Impacts of Land Cover Change and Dams on the Land–Water Interface of the Tocantins River

Mega-dams and extreme rainfall: Disentangling the drivers of extensive impacts of a large flooding event on Amazon Forests

Impacts of an Amazonian hydroelectric dam on frog assemblages

Contact Info

Product

Resources

About