John Ethan Householder- phd
- Researcher at Karlsruhe Institute of Technology
John Ethan Householder
- phd
- Researcher at Karlsruhe Institute of Technology
About
56
Publications
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1,311
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Introduction
Current institution
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January 2011 - present
Publications
Publications (56)
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...
Alluvial sediments bordering rivers of the southern Peruvian Amazon are enriched with gold, which has sustained an artisanal gold mining economy within a biodiversity hotspot for the past several decades. While it is clear that sweeping deforestation by miners has resulted in substantial loss of above-ground carbon stocks and increased greenhouse e...
Plants cope with the environment by displaying large phenotypic variation. Two spectra of global plant form and function have been identified: a size spectrum from small to tall species with increasing stem tissue density, leaf size, and seed mass; a leaf economics spectrum reflecting slow to fast returns on investments in leaf nutrients and carbon...
Amazonian floodplains are the most extensive and biodiverse riverine habitat on Earth. They currently face unprecedented fire regimes as climate change increases the frequency and intensity of drought. While it is clear that fire impacts on floodplain ecology can be severe, fire regimes and their effect on forest ecosystems have yet to be fully exa...
Unlike most rivers globally, nearly all lowland Amazonian rivers have unregulated
flow, supporting seasonally flooded floodplain forests. Floodplain forests harbor a
unique tree species assemblage adapted to flooding and specialized fauna, including
fruit-eating fish that migrate seasonally into floodplains, favoring expansive floodplain
areas....
The Amazon basin is undergoing an unprecedented transformation during recent decades driven by anthropogenic-dominated disturbance regimes and increasing hydroclimatic extremes. This affects the large Amazonian river-floodplains influenced by annual, regular and predictable flood pulses with high amplitudes, the várzeas and igapós, which cover an a...
Leaf and wood functional traits of trees are related to growth, reproduction, and survival, but the degree of phylogenetic conservatism in these relationships is largely unknown. In this study, we describe the variability of strategies involving leaf, wood and demographic characteristics for tree genera distributed across the Amazon Region, and qua...
RESUMO Os buritizais amazônicos são indicados pela monodominância da espécie de palmeira Mauritia flexuosa L.f. (buriti) e são pântanos com inundação permanente ou quase permanente sujeitos a um pulso de inundação de pequena amplitude. Por se formarem em cima de substratos relativamente impermeáveis, o regime hidrológico nos buritizais encontra-se...
We describe the geographical variation in tree species composition across Amazonian forests and show how environmental conditions are associated with species turnover. Our analyses are based on 2023 forest inventory plots (1 ha) that provide abundance data for a total of 5188 tree species. Within-plot species composition reflected both local enviro...
Tropical peatlands are among the most carbon-dense terrestrial ecosystems yet recorded. Collectively, they comprise a large but highly uncertain reservoir of the global carbon cycle, with wide-ranging estimates of their global area (441 025–1700 000 km²) and below-ground carbon storage (105–288 Pg C). Substantial gaps remain in our understanding of...
Wood density (WD) is a key functional trait for its importance in tree performance and in biomass calculations of forests. Yet, the variation of WD among different woody tree parts, how this varies across ecosystems, and how this influences estimates of forest carbon stocks remains little understood, particularly for diverse tropical forests such a...
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 w...
ARTICLE Mapping density, diversity and species-richness of the Amazon tree flora Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by fore...
Indigenous societies are known to have occupied the Amazon basin for more than 12,000 years, but the scale of their influence on Amazonian forests remains uncertain. We report the discovery, using LIDAR (light detection and ranging) information from across the basin, of 24 previously undetected
pre-Columbian earthworks beneath the forest canopy. Mo...
Graphical abstract Highlights d Ecological metadata were compiled for 7,694 sites across the Brazilian Amazon d Accessibility and proximity to research facilities influenced research probability d Knowledge gaps are greater in uplands than in wetlands and aquatic habitats d Undersampled areas overlap predicted hotspots of climate change and defores...
In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important...
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 ov...
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, hydrogeom...
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‐avail...
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 su...
Supplementary material of Gumbricht et al. 2017
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 Fra...
The large flood pulse of the Amazon basin is a principal driver of environmental heterogeneity with important implications for ecosystem function and the assembly of natural communities. Understanding species ecological response to the flood pulse is thus a key question with implications for theories of species coexistence, resource management, and...
In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important...
Aim - Peat swamps are a unique class of tropical forest characterized by their deep organic soils, which accrue from slowly decomposing plant debris.
Main Concepts Covered - We overview the environmental conditions that permit the development of peat swamp forests, from local processes that allow peat to accumulate, to the regional processes that d...
The potential natural vegetation (PNV) is a useful benchmark for the restoration of large river floodplains because very few natural reference reaches exist. Expert-based approaches and different types of ecological models (static and dynamic) are commonly used for its estimation despite the conceptual differences they imply. For natural floodplain...
We consolidate data from wetland forest inventories in Brazil and examine patterns of diversity and composition along temperature and rainfall gradients spanning five biomes. We detected a total of 2,453 tree species, with the Amazon alone accounting for nearly half. Compositional patterns indicated differences in freshwater wetland floras among Br...
European willows (Salicaceae) are pioneer species in temperate zone floodplains. The species are considered invasive and introduction can lead to substantial alteration of floodplain vegetation communities and ecosystem functioning. Invasive spread of different Salicaceae have been attributed to differences in flood tolerance, growth and dispersal...
Wetlands harbor an important compliment of regional plant diversity, but in many regions data on wetland diversity and composition is still lacking, thus hindering our understanding of the processes that control it. While patterns of broad-scale terrestrial diversity and composition typically correlate with contemporary climate it is not clear to w...
Distribution of Fisher’s alpha values in the investigated biomes, sensu Veloso [38].
Median values are indicated with a thick vertical line. Note that median values are relatively similar for the three best-sampled biomes (Amazon, Atlantic Forest, and Cerrado).
(TIFF)
Coverage-based species accumulation curves for each biome seperately and the combined dataset.
We used the function iNEXT from the ‘iNEXT’ package [56] with the settings iNEXT(x, q = 0, datatype = “incidence_freq”, conf = 0.95).
(TIFF)
Species checklist for wetland trees in Brazil.
Author names and synonymies were checked using the taxonomic name resolution service. Species frequencies are given for each biome.
(XLSX)
Non-metric multidimensional scaling of wetland vegetation communities.
The solution was optimized for two dimensions and rotated to principal components (see Fig 2). The main distinction with the principal components configuration is the relative position of Caatinga sites, which are more outlying in the NMDS. Fitted vectors are of WorldClim climat...
Quantile regression coefficients, intercepts, and 95% confidence intervals for all quantiles.
Generally, coefficients are nearly zero for the lower to mid quantiles of the distribution, but rapidly increase at the highest quantiles. The pattern indicates strong climate association only at maximal wetland tree diversity, driven by relatively few sit...
List of 196 freshwater wetland tree inventories collated for this study.
Biome sensu Veloso [38] is indicated by code (AM = Amazon, AF = Atlantic Forest, CERR = Cerrado, CAAT = Caatinga, PM = Pampas). The number of individuals and species were taken directly from each publication and used to calculate Fisher’s Alpha.
(DOCX)
Species x site data in three-column format.
(XLSX)
Density functions of diversity at opposite climate extremes.
Estimated density functions are based on the corresponding quantile regression solutions (see Fig 4) for all values of tau in 0 to 1. Estimates are presented for the 10th and 90th quantiles of each climate variable, as specified in the legend insets. Mean annual temperature is multiplied...
Wetlands are important providers of ecosystem services and key regulators of climate change. They positively contribute to global warming through their greenhouse gas emissions, and negatively through the accumulation of organic material in histosols, particularly in peatlands. Our understanding of wetlands' services is currently constrained by lim...
Knowledge of the environmental correlates of species’ distributions is essential for understanding population dynamics, responses to environmental changes, biodiversity patterns, and the impacts of conservation plans. Here we examine how environment controls the distribution of the neotropical genus Montrichardia at regional and local spatial scale...
Amazonian wetlands are subject to prolonged waterlogging, which is known to be a major determinant of local composition and species distributions. However, our understanding of which traits determine species distributions in Amazonian wetlands and how these traits evolved is still scant. Due to correspondence between species traits, the niche and b...
River wetlands have been an important landscape component of the Amazon Basin since the existence of neotropical rainforests. The modern Amazon landscape and its geomorphological history are intricately tied to its river wetlands and the ways in which they have reworked its surface. This chapter describes the principal ways in which river wetlands...
Prior investigation of Maurita flexuosa wetlands (MFWs) has emphasized the ecology and exploitation of the habitat’s dominant canopy vegetation - M. flexuosa. This focus has tended to reinforce the impression of a homogeneous MFW vegetation community; a prevailing perception that stands unquestioned.
Here we report on quantitative vegetation surve...
This review presents the current knowledge regarding South American wetlands and summarizes major outcomes of the implementation of the Ramsar Convention on Wetlands of International Importance for the South American continent. South America is the wettest continent on Earth, with wetlands accounting for ∼20% of its area. Wetlands harbor an excepti...
.The Amazon basin is covered by the most species-rich forests in the world and is considered to house many endemic tree species. Yet, most Amazonian ecosystems lack reliable estimates of their degree of endemism, and causes of tree diversity and endemism are intense matters of debate. We reviewed the spatial distribution of 658 of the most importan...
This study provides the first chemical investigation of wild-harvested fruits of Vanilla pompona ssp. grandiflora (Lindl.) Soto-Arenas developed in their natural habitat in the Peruvian Amazon. Flowers were hand-pollinated and the resulting fruits were analysed at different developmental stages using an HPLC-DAD method validated for the quantificat...
We present results of research concerning the distribution, depth, volume, geomorphology, and habitat diversity of peatlands in the southern Peruvian Amazon. We identified 295 peatlands covering 294 km2 and ranging in size from 10 to 3,500 ha. Individual peatlands were mostly restricted to the meander belt of the Madre de Dios River. Mean peat dept...
Investigations of the diversity and natural history of Vanilla are scarce, especially in the Amazon region. Considering that the cured, fragrant fruits of several species are traded in international markets and are an important cash crop for thousands of small-scale farmers in tropical regions, there is a surprising lack of published information co...
Minimal documentation exists for natural pollination in wild Vanilla spp., despite the economic importance of this genus, additionally commercial vanilla (V. planifolia Jacks.) is one of very few crops whose production depends entirely on artificial pollination. Flowering and fruiting phenology
of Vanilla
bicolor Lindl., a close relative of V. plan...
Upper Amazonian wetlands represent little studied, poorly understood, and grossly under protected systems. Scientific investigation of Amazonian wetlands is in its infancy; nor is there much known about their ecological services. Regionally, wetlands form a ubiquitous and significant component of floodplain habitat fed by perennial springs as well...
