- M.N. Alexiades (1)
- Esteban Alvarez (1)
- Atila Alves de Oliveira (1)
- J.L. Amaral (1)
- Alejandro Araujo-Murakami (1)
- E.J.M.M. Arets (1)
- Jérôme Chave (1)
- Gang Chen (1)
- K.G. Dexter (1)
- E.N. Honorio Coronado (1)
- S.L. Lewis (1)
- Luis M.T. Carvalho de (1)
- Brice Mora (1)
- Ryan P. Powers (1)
- R.T. Pennington (1)
Spatiotemporal patterns of tropical deforestation and forest degradation in response to the operation of the Tucuruí hydroelectricdam in the Amazon basin
Chen, Gang ; Powers, Ryan P. ; Carvalho, Luis M.T. de; Mora, Brice - \ 2015
Applied Geography 63 (2015). - ISSN 0143-6228 - p. 1 - 8.
Amazon basin - Deforestation - Forest degradation - GIS - Hydroelectric dam - Remote sensing - Spatiotemporal pattern - Statistical analysis
The planned construction of hundreds of hydroelectric dams in the Amazon basin has the potential to provide invaluable 'clean' energy resources for aiding in securing future regional energy needs and continued economic growth. These mega-structures, however, directly and indirectly interfere with natural ecosystem dynamics, and can cause noticeable tree loss. To improve our understanding of how hydroelectric dams affect the surrounding spatiotemporal patterns of forest disturbances, this case study integrated remote sensing spectral mixture analysis, GIS proximity analysis and statistical hypothesis testing to extract and evaluate spatially-explicit patterns of deforestation (clearing of entire forest patch) and forest degradation (reduced tree density) in the 80,000km2 neighborhoods of the Brazil's Tucuruí Dam, the first large-scale hydroelectric project in the Amazon region, over a period of 25 years from 1988 to 2013. Results show that the average rates of deforestation were consistent during the first three time periods 1988-1995 (620km2 per year), 1995-2001 (591km2 per year), and 2001-2008 (660km2 per year). However, such rate dramatically fell to half of historical levels after 2008, possibly reflecting the 2008 global economic crisis and enforcement of the Brazilian Law of Environmental Crimes. The rate of forest degradation was relatively stable from 1988 to 2013 and, on average, was 17.8% of the rate of deforestation. Deforestation and forest degradation were found to follow similar spatial patterns across the dam neighborhoods, upstream reaches or downstream reaches at the distances of 5km-80km, suggesting that small and large-scale forest disturbances may have been influencing each other in the vicinity of the dam. We further found that the neighborhoods of the Tucuruí Dam and the upstream region experienced similar degrees of canopy loss. Such loss was mainly attributed to the fast expansion of the Tucuruí town, and the intensive logging activities alongside major roads in the upstream reservoir region. In contrast, a significantly lower level of forest disturbance was discovered in the downstream region.
Phylogenetic diversity of Amazonian tree communities
Honorio Coronado, E.N. ; Dexter, K.G. ; Pennington, R.T. ; Chave, Jérôme ; Lewis, S.L. ; Alexiades, M.N. ; Alvarez, Esteban ; Alves de Oliveira, Atila ; Amaral, J.L. ; Araujo-Murakami, Alejandro ; Arets, E.J.M.M. - \ 2015
Diversity and Distributions 21 (2015)11. - ISSN 1366-9516 - p. 1295 - 1307.
Amazon basin - Eudicots - Magnoliids - Monocots - Phylogenetic diversity - Species richness
Aim: To examine variation in the phylogenetic diversity (PD) of tree communities across geographical and environmental gradients in Amazonia. Location: Two hundred and eighty-three c. 1 ha forest inventory plots from across Amazonia. Methods: We evaluated PD as the total phylogenetic branch length across species in each plot (PDss), the mean pairwise phylogenetic distance between species (MPD), the mean nearest taxon distance (MNTD) and their equivalents standardized for species richness (ses.PDss, ses.MPD, ses.MNTD). We compared PD of tree communities growing (1) on substrates of varying geological age; and (2) in environments with varying ecophysiological barriers to growth and survival. Results: PDss is strongly positively correlated with species richness (SR), whereas MNTD has a negative correlation. Communities on geologically young- and intermediate-aged substrates (western and central Amazonia respectively) have the highest SR, and therefore the highest PDss and the lowest MNTD. We find that the youngest and oldest substrates (the latter on the Brazilian and Guiana Shields) have the highest ses.PDss and ses.MNTD. MPD and ses.MPD are strongly correlated with how evenly taxa are distributed among the three principal angiosperm clades and are both highest in western Amazonia. Meanwhile, seasonally dry tropical forest (SDTF) and forests on white sands have low PD, as evaluated by any metric. Main conclusions: High ses.PDss and ses.MNTD reflect greater lineage diversity in communities. We suggest that high ses.PDss and ses.MNTD in western Amazonia results from its favourable, easy-to-colonize environment, whereas high values in the Brazilian and Guianan Shields may be due to accumulation of lineages over a longer period of time. White-sand forests and SDTF are dominated by close relatives from fewer lineages, perhaps reflecting ecophysiological barriers that are difficult to surmount evolutionarily. Because MPD and ses.MPD do not reflect lineage diversity per se, we suggest that PDss, ses.PDss and ses.MNTD may be the most useful diversity metrics for setting large-scale conservation priorities.