Torbjørn Haugaasen

Norwegian University of Life Sciences (NMBU) · Faculty of Environmental Sciences and Natural Resource Management (MINA)

Selective logging is a major form of land use in tropical rainforests, with more than half of the world's tropical forest already explored. In the Brazilian Amazon, most logging operations are illegal and highly damaging to forests. However, the effects of illegal logging on wildlife are poorly studied. Here we investigate the effects of illegal lo...

The persistent high deforestation rate and fragmentation of the Amazon forests are the main threats to their biodiversity. To anticipate and mitigate these threats, it is important to understand and predict how species respond to the rapidly changing landscape. The short-eared dog Atelocynus microtis is the only Amazon-endemic canid and one of the...

Flying foxes play keystone ecological roles in plant reproduction. Yet, they face numerous threats, including persecution for eating commercial fruits. This human-wildlife conflict has recently escalated to culling campaigns of a threatened flying fox on Mauritius. Finding non-lethal solutions to this human-wildlife conflict on the island is theref...

The conversion of natural habitats to farmland is a major driver of the global extinction crisis [1, 2]. Two strategies are promoted to mitigate the impacts of agricultural expansion on biodiversity: land sharing integrates wildlife-friendly habitats within farmland landscapes, and land sparing intensifies farming to allow the offset of natural res...

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...

The wildlife trade is a billion-dollar global business, involving millions of people, thousands of species, and hundreds of millions of individual organisms. Unravelling whether trade targets reproductively distinct species and whether this preference varies between captive and wild-sourced species is a crucial question. We use a comprehensive list...

Species relative abundance (SRA) is an essential attribute of biotic communities, which can provide an accurate description of community structure. However, the sampling method used may have a direct influence on SRA quantification, since the use of at-tractants (e.g., baits, light, and pheromones) can introduce additional sources of variation in t...

The rise in species richness with area is one of the best-studied patterns in ecology. Yet, little is known about the spatial scaling of alternate dimensions of diversity. Here, we provide empirical evidence for a relationship between the richness of acoustic traits emanating from the landscape, or soundscape richness, and the island area, which we...

The Amazon is one of the most diverse biomes around the globe, currently threatened by economic and industrial development and climate change. Large mammals are keystone species, playing an important role in ecosystem structure and function as ecological engineers, while being highly susceptible to deforestation, habitat degradation , and human exp...

The seasonal flood pulse in Amazonia can be considered a primary driver of community structure in floodplain environments. Although this natural periodic disturbance is part of the landscape dynamics, the seasonal inundation presents a considerable challenge to organisms that inhabit floodplain forests. The present study investigated the effect of...

Global warming is a great threat to biodiversity with negative impacts spanning the entire biological hierarchy. One of the main species’ traits determining survival at higher temperature is the thermal point at which an animal loses its ability to escape from deadly conditions (critical thermal maximum—CTmax). Variation in CTmax across species is...

Habitat conversion is a major driver of tropical biodiversity loss, but its effects are poorly understood in montane environments. While community‐level responses to habitat loss display strong elevational dependencies, it is unclear whether these arise via elevational turnover in community composition and interspecific differences in sensitivity,...

Ecologists often seek to infer patterns of species occurrence or community structure from survey data. Hierarchical models, including multi‐species occupancy models (MSOMs), can improve inference by pooling information across multiple species via random effects. Originally developed for local‐scale survey data, MSOMs are increasingly applied to lar...

Fruits and seeds are key food resources for most Amazonian mammals and birds. Selective logging is an increasingly dominant land use in the region that can deplete these resources over large areas. However, this potential impact remains poorly studied. Here we assess potential losses of animal-dispersed (endozoochorous and synzoochorous) trees resu...

The ‘Critically Endangered’ Black-winged Trumpeter Psophia obscura is endemic to the Belém Centre of Endemism in extreme eastern Amazonia and has a declining population and range. Here we report on a five-year (2016–2020) systematic camera-trap (n = 61) study of the species in Gurupi Biological Reserve, one of its most important conservation areas....

Soundscape studies are increasingly used to capture landscape‐scale ecological patterns. Yet, several aspects of soundscape diversity remain unexplored. Although some processes influencing acoustic niche usage may operate in the 24‐hr temporal domain, most acoustic indices only capture the diversity of sounds co‐occurring in sound files at a specif...

Rapid development of remote sensing and LiDAR technology has refined estimates of tree architecture and extrapolation of biomass across large spatial scales. Yet, current biomass maps show significant discrepancies and mismatch to independent ground data. A potential obstacle to accurate biomass estimation is the loss of information on wood density...

The domestic cat ( Felis catus ) is among the most popular companion animals and most abundant carnivores globally. It is also a pet with an immense ecological footprint because even non-feral and food-subsidized cats can be prolific predators. Whereas knowledge about the spatial behavior of individual domestic cats is growing, we still know little...

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) regulates international legal trade to prevent the detrimental harvest of wildlife. We assess the volumes of threatened and non-threatened bird, mammal, amphibian, and reptile species in the CITES-managed trade and how this trade responded to category change...

1. Soundscape studies are increasingly common to capture landscape-scale ecological patterns. Yet, several aspects of soundscape diversity quantification remain unexplored. Although some processes influencing acoustic niche usage may operate in the 24h domain, most acoustic indices only capture the diversity of sounds co-occurring in sound files at...

The domestic cat (Felis catus) is the most popular companion animal and the most abundant carnivore globally. It is also a pet with an immense ecological footprint, because even non-feral and food-subsidized cats are prolific predators. Whereas knowledge about the spatial behavior of individual domestic cats is growing, we still know little about h...

Amazonia encompasses extensive forests in areas that are periodically inundated by overflowing rivers. The inundation depth and duration vary according to the slope of the terrain and distance to major water bodies. This creates a flooding gradient from the lowest lying seasonally flooded forest up into the unflooded forest, which directly affects...

Ecologists often seek to infer patterns of species occurrence or community structure from survey data. Hierarchical models, including multi-species occupancy models (MSOMs), can improve inference by pooling information across multiple species via random effects. Originally developed for local-scale survey data, MSOMs are increasingly applied to lar...

Significance Sustainable-use protected areas (PAs) have contributed to tropical biodiversity conservation by deterring deforestation in multiple countries, yet their social and economic benefits to local stakeholders remain poorly understood. Amazonia hosts the largest tropical PA system on Earth, which is intended to safeguard its rich biological...

Production forests are a dominant feature of most tropical forest landscapes and it is therefore important to understand the effects of timber extraction on the resident fauna. Here we investigate the effects of reduced-impact logging (RIL) on medium-to large-sized terrestrial mammals in two Jamari National Forest logging concessions, southwestern...

The annual flooding in the Amazon basin transforms the understory of floodplain forests into an aquatic environment. However, a great number of non-aquatic bird species occupy the understory and midstory of these forests. In general, these birds are thought to be sedentary and territorial, but the way they adapt to this dramatic seasonal transforma...

Amazonia comprises a mosaic of contrasting habitats, with wide environmental heterogeneity at local and regional scales. In central Amazonia, upland forest (terra firme) is the predominant forest type and seasonally flooded forests inundated by white- and black-water rivers (várzea and igapó, respectively) represent around 20% of the forested areas...

Animal coloring serves several functions, including camouflage and thermoregulation. However, some individuals have anomalous coloring patterns due to excess (melanism) or deficiency (albinism, leucism, or piebaldism) in melanin production. Although these anomalies occur in several species, there are few cited cases. Here, we report the occurrence...

An understanding of a species' geographic distribution is essential to assess, plan, and develop strategies for its conservation. The geographic distribution of the bald uakari, Cacajao calvus, and its component subspecies has been poorly investigated, with disjunct distributions being reported in Brazil and Peru. In this study, we reveal new recor...

Amazonia encompasses forests that grow in areas that are periodically inundated by overflowing rivers. The inundation depth and duration vary according to the slope of the terrain, creating a flooding gradient. This gradient directly affects the biota, but the effect on soil organisms remains elusive. Here, we use DNA metabarcoding to estimate prok...

Meeting rising demand for oil palm whilst minimizing the loss of tropical biodiversity and associated ecosystem functions is a core conservation challenge. One potential solution is focusing the expansion of high-yielding crops on presently low-yielding farmlands alongside protecting nearby tropical forests that can enhance provision of ecosystem f...

The wildlife trade is worth billions of dollars annually and affects most major taxonomic groups. Despite this, a global understanding of the trade’s impacts on species populations is lacking. We performed a quantitative meta-analysis of the wildlife trade that synthesized 506 species-level effect sizes from 31 studies, estimating trade-driven decl...

Effectively managing farming to meet food demand is vital for the future of biodiversity.¹,² Increasing yields on existing farmland can allow the abandonment (sparing) of low-yielding areas that subsequently recover as secondary forest.2, 3, 4, 5 A key question is whether such “secondary sparing” conserves biodiversity more effectively than retaini...

Research Highlights: Rare, or sparsely distributed, species drive the floristic diversity of upland, terra firme and seasonally flooded forests in the central Juruá-a remote and hitherto floristically poorly known area in the Brazilian Amazon. Background and Objectives: Floristic inventories are critical for modelling and understanding the role of...

The tropical rainforests of Sundaland are a global biodiversity hotspot increasingly threatened by human activities. While parasitic insects are an important component of the ecosystem, their diversity and parasite-host relations are poorly understood in the tropics. We investigated parasites of passerine birds, the chewing lice of the speciose gen...

For tropical tree species, wood density can vary greatly both within and between species depending on environmental conditions. In Amazonian seasonally flooded forests, yearly flood pulses influence tree growth and floodplain trees have developed specialised strategies to cope with prolonged submersion during flooding. We therefore hypothesised tha...

Global warming is having impacts across the Tree of Life. Understanding species’ physiological sensitivity to temperature change and how they relate to local temperature variation in their habitats is crucial to determining vulnerability to global warming. We ask how species’ vulnerability varies across habitats and elevations, and how climatically...

We investigated short-eared dog habitat associations on two spatial scales. First, we used the largest record database ever compiled for short-eared dogs in combination with species distribution models to map species habitat suitability, estimate its distribution range and predict shifts in species distribution in response to predicted deforestatio...

For arboreal primates, ground use may increase dispersal opportunities, tolerance to habitat change, access to ground-based resources, and resilience to human disturbances, and so has conservation implications. We collated published and unpublished data from 86 studies across 65 localities to assess titi monkey (Callicebinae) terrestriality. We exa...

Natural regeneration of abandoned farmland provides an important opportunity to contribute to global reforestation targets, including the Bonn Challenge. Of particular importance are the montane tropics, where a long history of farming, frequently on marginal soils, has rendered many ecosystems highly degraded and hotspots of extinction risk. Ants...

The ecological impacts of meeting rising demands for food production can potentially be mitigated by two competing land‐use strategies: off‐setting natural habitats through intensification of existing farmland (land sparing), or elevating biodiversity within the agricultural matrix via the integration of ‘wildlife‐friendly’ habitat features (land s...

The importance of tropical forests in regulating global carbon stocks is well known. However, the role of abiotic variables related to climate conditions and edaphic parameters for patterns of above-ground woody biomass (AGWB) are still under debate. For Amazonian forests subjected to periodic floods, these patterns are even more uncertain. This st...

Secondary forests are promoted as having pivotal roles in reversing the tropical extinction crisis. While secondary forests recover carbon and species over time, a key question is whether phylogenetic diversity—the total evolutionary history across all species within a community—also recovers. Conserving phylogenetic diversity protects unique pheno...

Floodplain forests cover extensive areas of the Amazon basin, but the number of tree inventories is low. Vast floodplain regions therefore remain floristically unknown. We present a quantitative inventory of floodplain forests from four Amazon river basins (Jutaí, Juruá, Tefé and Purus), investigate within- and between-basin floristic similarity, a...

Given the dramatic loss of tropical forests and accelerating climate change, secondary forest regeneration is increasingly recognised as being an important method for reversing losses in biodiversity and carbon stocks. The recolonisation of biodiversity within secondary forests depends in part upon the recovery of forest structure, including the ra...

Most terrestrial species on Earth are ectothermic and track temperature at small spatial scales, from sun flecks to cool shaded spots. Current assessments of thermal heterogeneity in complex environments are predominately characterized by ambient temperature. This omission of solar radiation may lead to inaccurate conclusions regarding thermoregula...

Anuran frogs are often considered generalist predators in rice fields and feed upon a variety of invertebrates. They may thus provide an invaluable ecosystem service, as many species belonging to the orders coleoptera, lepidoptera, orthoptera, homoptera and hemiptera are regarded as notorious rice pests, inflicting significant losses on rice produc...

Tropical land-use change is a key driver of global declines in biodiversity and a major source of anthropogenic carbon emissions, yet there is a substantial shortfall in the funding available to tackle these issues. We urgently need mechanisms that can simultaneously tackle both biodiversity and carbon losses, with carbon-based payments for ecosyst...

Seasonal flooding compels some birds that breed in aquatic habitats in Amazonia to undertake annual migrations, yet we know little about how the complex landscape of the Amazon region is used seasonally by these species. The possibility of trans-Andes migration for Amazonian breeding birds has largely been discounted given the high geographic barri...

The expansion of tropical agriculture is a major driver of the extinction crisis. A key question is whether biodiversity losses can be minimized by restricting future expansion to low‐productivity farmland and retaining forest fragments, especially in rapidly changing Neotropical landscapes. We investigated these methods in the context of avian phy...

Various techniques have been used to estimate the age of Brazil nut trees (Bertholletia excelsa Bonpl.), but these techniques produce large discrepancies. Here, we first verified that two individuals of known ages from a plantation in central Amazonia, Brazil, have a congruent number of growth rings. The indexed average tree-ring curve was signific...

Pitheciids are known for their frugivorous diets, but there has been no broad-scale comparison of fruit genera used by these primates that range across five geographic regions in South America. We compiled 31 fruit lists from data collected from 18 species (three Cacajao, six Callicebus, five Chiropotes, and four Pithecia) at 26 study sites in six...

We examined anuran frog assemblages along an elevational gradient in the range of 200–1600 m.a.s.l. in Chitwan, Nepal. Using diurnal and nocturnal transect surveys, we investigated patterns of frog species richness and abundance on the southern and northern slopes of Siraichuli hill. A total of 17 frog species of four families were recorded during...

The Near-threatened Orinoco Goose Neochen jubata is a poorly known South American sheldgoose with a declining population and range distribution. In this study, we surveyed the Orinoco Goose population along the middle reaches of the Rio Juruá, western Brazilian Amazonia, and its first-order tributaries. We quantified the seasonal abundance of geese...

Species persistence in human-altered landscapes can depend on factors operating at multiple spatial scales. To understand anthropogenic impacts on biodiversity, it is useful to examine relationships between species traits and their responses to land-use change. A key knowledge gap concerns whether these relationships vary depending on the scale of...

It is well established that tree assemblage diversity and composition in Amazonian floodplain forest are influenced by substrate properties and hydroperiod. However, no study to date has tried to disentangle the individual effects of these variables on floodplain tree assemblages. In this study, we investigated the influence of several edaphic vari...

QuestionIn a recent re-classification of Amazonian floodplain types, a new category was established for paleo-várzea. Although the geological basis for this classification is sound, a key question is whether it can be supported by botanical criteria, where floodplain paleo-várzea forests contain distinct tree assemblages compared to other major flo...

Oil palm agriculture is rapidly expanding in the Neotropics, at the expense of a range of natural and seminatural habitats. A key question is how this expansion should be managed to reduce negative impacts on biodiversity. Focusing on the Llanos of Colombia, a mixed grassland–forest system identified as a priority zone for future oil palm developme...

Two strategies are often promoted to mitigate the effects of agricultural expansion on biodiversity: one integrates wildlife‐friendly habitats within farmland (land sharing), and the other intensifies farming to allow the offset of natural reserves (land sparing).