71 research outputs found
Perspectivas Macroecológicas Nas Áreas Úmidas Dominadas Por Mauritia Na Amazônia
The palm genus Mauritia L.f (Arecaceae) is a principal component of Neotropical freshwater
swamp and flooded-savanna vegetation. As such, these palms indicate near-permanent
waterlogging at or near ground surface. In this study, expeditionary and exploratory research
was undertaken to sample the woody vegetation communities of Mauritia-dominated
wetlands (MDWs). A total of 28 MDWs were quantitatively sampled in the Brazilian and
Peruvian Amazon. Field work resulted in >3000 botanical collections accompanied by >8000
photographic images made publically available through online resources
(http://atrium.andesamazon.org/). Over 40,000 individual woody stems were documented,
distributed among 89 families, 318 genera and ~750 woody species. Taking advantage of the
indicator status of Mauritia for near-permanently waterlogged substrates – an extreme abiotic
condition in the region - the community ecology of woody vegetation of this common
Amazonian wetland habitat was investigated across a broad spatial scale regarding its
taxonomic, phylogenetic, and biogeographic structure. Data indicate reduced local site
richness in MDW vegetation communities, consistent with previous investigation. Over
broad spatial scales results show that rather than being comprised of a predictable set of
habitat specialists, MDWs exhibit high site-to-site compositional variability relative to
surrounding upland forest vegetation. Community phylogenetic analyses reveal that the
ability to occupy MDWs is widely distributed in a phylogenetically diverse array of
Amazonian forest taxa. Biogeographic analyses reveal that assemblages demonstrate
consistent patterns of compositional turnover along local stress gradients, transitioning from
largely Amazonian-distributed lineages in forested sites to increasingly extra-Amazoniandistributed
lineages in shrubby sites. I suggest that traditionally perceived patterns of
community homogeneity of MDWs occur alongside previously underappreciated patterns of
taxonomic, phylogenetic, and functional diversity. Taking the results together, I argue that
comparative analyses of MDW communities offer unique insight into current models of
Amazonian plant and ecosystem diversity that are based almost completely on upland forests,
contributing to both Amazonian biodiversity theory (Chapter 1 and 2) and applied science
(Chapter 3).O gênero das palmeiras Mauritia L.f. (Arecaceae) é o componente principal de áreas
pantanosas neotropicais e da vegetação de muitas savanas inundadas. A presença deste gênero
indica condições de inundação permanente na superfície e/ou próximo à superfície do solo.
No presente estudo, foram realizados inventários florísticos em comunidades lenhosas de
áreas úmidas dominadas por Mauritia, os buritizais. Na Amazônia brasileira e peruana, um
número total de 28 buritizais foi inventariado. O trabalho de campo resultou em mais de 3.000
coletas botânicas, e mais de 8.000 fotografias, publicamente acessíveis em herbário digital
(http://atrium.andesamazon.org/). Mais de 40.000 indivíduos lenhosos foram levantados,
distribuídos em 89 famílias, 318 gêneros e aproximadamente 750 espécies. Utilizando o
gênero Mauritia como indicador de substratos permanentemente alagados, uma condição
abiótica extrema na região, a ecologia da comunidade lenhosa deste importante habitat úmido
Amazônico foi investigada ao longo de uma grande escala espacial em função de sua
composição taxonômica, filogenética e biogeográfica. Os dados indicam que a comunidade de
vegetação dos buritizais apresenta uma riqueza florística reduzida, consistente com o
conhecimento disponível em literatura. Ao longo de ampla escala espacial, os resultados
indicam que os buritizais apresentam uma alta variabilidade na composição florística entre
diferentes sítios em comparação com a flora de terra firme. As analises filogenéticas
revelaram que o uso do habitat de buritizais provavelmente é um atributo amplamente
presente na filogenia de ecossistemas florestados Amazônicos. As analises biogeográficas
mostraram que as comunidades demonstram um padrão consistente de substituição
composicional ao longo de gradientes de estresse, com uma transição de linhagens
majoritariamente Amazônicas em sítios florestados para linhagens majoritariamente extraamazônicas
em sítios arbustivos. É sugerido que o padrão de homogeneidade florística dos
buritizais, como tradicionalmente notado, ocorre em conjunto com um padrão de alta
diversidade taxonômica, filogenética e funcional, fato muitas vezes subestimado até o
momento. Argumenta-se que as análises comparativas de comunidades de buritizais oferecem
uma abordagem inovadora e única sobre os recentes modelos de diversidade especifica e
ecossistêmica, que até o presente, baseiam-se quase que inteiramente em florestas de terra
firme. Desta maneira, os resultados aqui apresentados contribuem tanto para as teorias de
biodiversidade nos capítulos 1 e 2, quanto para a ciência aplicada no capitulo 3
Using the River Ecosystem Service Index to evaluate “Free Moving Rivers” restoration measures: A case study on the Ammer river (Bavaria)
Restoring natural fluvial dynamics is fundamental for sustaining biodiversity and functional integrity of river and floodplain ecosystems. In Central Europe, however, pervasive river regulation and bank protection have greatly impaired ecosystem functioning and many water bodies fail to achieve a good ecological status within the European Water Framework Directive. The “Free Moving Rivers” approach seeks to restore the ecological integrity of rivers and floodplains by creating appropriate conditions for natural fluvial dynamics. Principal goals of the approach include removing artificial constraints on river processes and expanding the river corridor to restore natural river habitats and structures. Lacking, however, are complementary tools that evaluate and predict changes to ecosystem services (ESSs) after implementation. Here, we describe a case study of the Ammer river in Bavaria, Germany, to (i) calculate the extent of the “Free Moving Rivers” corridor, and (ii) assess changes to ESSs of a proposed river restoration measure under two alternative land-use scenarios. To do this, we apply the River Ecosystem Service Index (RESI), whereby individual ESSs are assessed in a spatially explicit way. We show how a proposed implementation of the “Free Moving Rivers” approach enhances three investigated ESSs: flood retention, sediment balance and habitat provision. We conclude that RESI is a potentially useful tool with wide applicability for restoration planning that synthesises floodplain complexity in such a way that facilitates decision making
One sixth of Amazonian tree diversity is dependent on river floodplains
Amazonia’s floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region’s floodplain forests. We show that the majority of Amazonian tree species can inhabit floodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on floodplains. The degree of specialization in floodplain communities is driven by regional flood patterns, with the most compositionally differentiated floodplain forests located centrally within the fluvial network and contingent on the most extraordinary flood magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of floodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon’s tree diversity and its function
A Review of the Ecological and Biogeographic Differences of Amazonian Floodplain Forests
Amazonian floodplain forests along large rivers consist of two distinct floras that are traced to their differentiated sediment- and nutrient-rich (várzea) or sediment- and nutrient-poor (igapó) environments. While tree species in both ecosystems have adapted to seasonal floods that may last up to 270–300 days year−1, ecosystem fertility, hydrogeomorphic disturbance regimes, water shortage and drought, fire, and even specific microclimates are distinct between both ecosystems and largely explain the differences in forest productivity and taxonomic composition and diversity. Here, we review existing knowledge about the influence of these environmental factors on the tree flora of both ecosystems, compare species composition and diversity between central Amazonian várzeas and igapós, and show that both ecosystems track distinct species life-history traits. The ecosystem-level and taxonomic differences also largely explain the biogeographic connections of várzeas and igapós to other Amazonian and extra-Amazonian ecosystems. We highlight the major evolutionary force of large-river wetlands for Amazonian tree diversity and explore the scenarios by which the large number of Amazonian floodplain specialist tree species might even contribute to the gamma diversity of the Amazon by generating new species. Finally, we call attention to the urgent need of an improved conservation of Amazonian várzea and igapó ecosystems and their tree species
Soil fertility and drought interact to determine large variations in wood production for a hyperdominant Amazonian tree species
Introduction: The productivity of the Amazon Rainforest is related to climate and soil fertility. However, the degrees to which these interactions influence multiannual to decadal variations in tree diameter growth are still poorly explored.
Methods: To fill this gap, we used radiocarbon measurements to evaluate the variation in tree growth rates over the past decades in an important hyperdominant species, Eschweilera coriacea (Lecythidaceae), from six sites in the Brazilian Amazon that span a range of soil properties and climate.
Results: Using linear mixed-effects models, we show that temporal variations in mean annual diameter increment evaluated over a specific time period reflect interactions between soil fertility and the drought index (SPEI-Standardized Precipitation and Evapotranspiration Index).
Discussion: Our results indicate that the growth response of trees to drought is strongly dependent on soil conditions, a facet of forest productivity that is still underexplored, and which has great potential for improving predictions of future tropical tree growth in the face of projected climate change
Risks to carbon storage from land-use change revealed by peat thickness maps of Peru
This work was funded by NERC (grant ref. NE/R000751/1) to I.T.L., A.H., K.H.R., E.T.A.M., C.M.A., T.R.B., G.D. and E.C.D.G.; Leverhulme Trust (grant ref. RPG-2018-306) to K.H.R., L.E.S.C. and C.E.W.; Gordon and Betty Moore Foundation (grant no. 5439, MonANPeru network) to T.R.B., E.N.H.C. and G.F.; Wildlife Conservation Society to E.N.H.C.; Concytec/British Council/Embajada Británica Lima/Newton Fund (grant ref. 220–2018) to E.N.H.C. and J.D.; Concytec/NERC/Embajada Británica Lima/Newton Fund (grant ref. 001–2019) to E.N.H.C. and N.D.; the governments of the United States (grant no. MTO-069018) and Norway (grant agreement no. QZA-12/0882) to K.H.; and NERC Knowledge Exchange Fellowship (grant ref no. NE/V018760/1) to E.N.H.C.Tropical peatlands are among the most carbon-dense ecosystems but land-use change has led to the loss of large peatland areas, associated with substantial greenhouse gas emissions. To design effective conservation and restoration policies, maps of the location and carbon storage of tropical peatlands are vital. This is especially so in countries such as Peru where the distribution of its large, hydrologically intact peatlands is poorly known. Here field and remote sensing data support the model development of peatland extent and thickness for lowland Peruvian Amazonia. We estimate a peatland area of 62,714 km2 (5th and 95th confidence interval percentiles of 58,325 and 67,102 km2, respectively) and carbon stock of 5.4 (2.6–10.6) PgC, a value approaching the entire above-ground carbon stock of Peru but contained within just 5% of its land area. Combining the map of peatland extent with national land-cover data we reveal small but growing areas of deforestation and associated CO2 emissions from peat decomposition due to conversion to mining, urban areas and agriculture. The emissions from peatland areas classified as forest in 2000 represent 1–4% of Peruvian CO2 forest emissions between 2000 and 2016. We suggest that bespoke monitoring, protection and sustainable management of tropical peatlands are required to avoid further degradation and CO2 emissions.PostprintPeer reviewe
One sixth of Amazonian tree diversity is dependent on river floodplains
Amazonia’s floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region’s floodplain forests. We show that the majority of Amazonian tree species can inhabit floodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on floodplains. The degree of specialization in floodplain communities is driven by regional flood patterns, with the most compositionally differentiated floodplain forests located centrally within the fluvial network and contingent on the most extraordinary flood magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of floodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon’s tree diversity and its function
Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates
Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis).
Time period: Tree-inventory plots established between 1934 and 2019.
Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm.
Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield.
Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes.
Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests.
Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types
Geography and ecology shape the phylogenetic composition of Amazonian tree communities
Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types.
Location: Amazonia.
Taxon: Angiosperms (Magnoliids; Monocots; Eudicots).
Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran\u27s eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny.
Results: In the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R = 28%). A greater number of lineages were significant indicators of geographic regions than forest types.
Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions
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