The island of New Guinea is home to the third largest continuous rainforest in the world, which is increasingly threatened by large-scale deforestation and forest conversion. Despite this, there is little scientific data on the highly biodiverse local avifauna and in particular on its response to anthropogenic disturbances. We seek to address this problem by examining bird assemblages in human-altered rainforests in lowland Papua New Guinea. We surveyed birds using point counts (N = 160 over 90 survey days) in four forest types: a continuous primary forest control site; secondary forests regrown after small-scale agriculture; primary forest fragments isolated by logging; and secondary forests regrown after clear-cutting. We employed generalized linear mixed-effects models to analyze bird species richness, assemblage density, and community structure. We found that total bird species richness decreased significantly in all human-modified forests, while total density did not. Moreover, we found that different feeding guilds showed contrasting response to disturbances. Small-scale agriculture resulted in slight decreases of insectivore species richness but did not impact other guilds. However, in primary forest fragments, habitat isolation and loss of forest connectivity severely impacted both insectivores and frugivores. Moreover, in secondary forests regrown after clear-cutting, fragmentation was compounded with changes to forest structure, resulting in collapse of insectivore species richness and density. On the other hand, nectarivores responded positively to forest alteration, with increased assemblage density in all human-modified forests. Our results show that changes to forest structure come second to fragmentation in their negative effects on bird species. Retaining connectivity with contiguous primary forests is crucial for maintaining the bulk of avian biodiversity. As logging concessions expand across Papua New Guinea, conserving large, intact forest reserves will be essential for sustaining the region's unique avifauna.

Avian biodiversity in tropical rainforests is threatened by increasing intensity of anthropogenic disturbances. Secondary forest birds can maintain ecosystem services that are otherwise lost with disappearing primary forests. However, the stability of these services can be impeded by area effects reducing bird diversity. We compared the effects of fragmentation on avian ecosystem functions in both primary and secondary forests. We performed point count surveys in both continuous rainforests, as well as isolated forest fragments in lowland Papua New Guinea. We combined taxonomic diversity with functional and phylogenetic indices and patterns of individual functional traits. Bird taxonomic diversity was lower in secondary forests and decreased considerably due to fragmentation. In contrast, functional diversity was not affected by fragmentation but increased in secondary forests. Phylogenetic diversity increased in all human‐modified forests. Decreases in taxonomic diversity stemmed from the loss of forest‐dependent birds. In contrast, decreases in functional and phylogenetic diversity were prevented by the introduction of open‐habitat species. This was demonstrated by shifts in trait composition, as bird phenotypes reliant on forest continuity became less prevalent. Specifically, we recorded a proportional decrease in insectivory and ground foraging, and an increase in nectarivory and dispersal ability. Increased dispersal ability was also observed in secondary forests, where it was associated with shifts towards frugivory and canopy foraging. Increases in phylogenetic diversity were likely amplified by high phylogenetic dispersion of introduced habitat generalists. Policy implications . We show that compensatory patterns of species introduction fail to account for the loss of ecosystem functions due to the decline of forest‐dependent birds. As such, conservation policies should be targeted towards species that share traits associated with disturbance sensitivity, such as insectivory, ground foraging and low dispersal ability. This could prevent biodiversity loss in poorly explored tropical landscapes in the early stages of large‐scale deforestation.

Insect herbivory plays a crucial role in shaping plant communities in many terrestrial ecosystems. However, in African savannas, insect herbivory has been relatively understudied compared to large mammalian herbivory. In this study, we examined the impact of insect herbivory, focusing on leaf chewers and miners, in a South African savanna-forest mosaic (including patches of forest, thicket and savanna) in Hluhluwe iMfolozi Park, South Africa. Our investigation spanned gradients of rainfall, fire frequency and mammal density. We surveyed a total of 864 woody plants from 48 plant species in 38 plots. Insects consumed 6% of leaf biomass, which is comparable to their impact in temperate broadleaf forests, but the extent of herbivory damage varied between vegetation types. Overall, leaf loss was 70% higher in forests and savanna than that in thicket. Plants in the forests experienced greater damage from chewing insects, whereas miners caused relatively more damage in savannas. Rates of insect herbivory also varied among plant species, declining with carbon and dry matter content but increasing with specific leaf area. Although no significant trade-off was detected between insect and mammal herbivory, plant species with limited physical defences against mammals tended to experience high levels of insect herbivory. Our findings highlight the intricate dynamics of insect herbivory in different vegetation types and suggest that insect leaf herbivory, alongside mammalian herbivory, could play a significant role in influencing plant community composition and overall savanna ecosystem functioning.

Birds, bats, and ants are recognized as significant arthropod predators. However, empirical studies reveal inconsistent trends in their relative roles in top-down control across strata. Here, we describe the differences between forest strata in the separate effects of birds, bats, and ants on arthropod communities and their cascading effects on plant damage. We implemented a factorial design to exclude vertebrates and ants in both the canopy and understory. Additionally, we separately excluded birds and bats from the understory using diurnal and nocturnal exclosures. At the end of the experiments, we collected all arthropods and assessed herbivory damage. Arthropods responded similarly to predator exclusion across forest strata, with a density increase of 81% on trees without vertebrates and 53% without both vertebrates and ants. Additionally, bird exclusion alone led to an 89% increase in arthropod density, while bat exclusion resulted in a 63% increase. Herbivory increased by 42% when vertebrates were excluded and by 35% when both vertebrates and ants were excluded. Bird exclusion alone increased herbivory damage by 28%, while the exclusion of bats showed a detectable but non-significant increase (by 22%). In contrast, ant exclusion had no significant effect on arthropod density or herbivory damage across strata. Our results reveal that the effects of birds and bats on arthropod density and herbivory damage are similar between the forest canopy and understory in this temperate forest. In addition, ants were not found to be significant predators in our system. Furthermore, birds, bats, and ants appeared to exhibit antagonistic relationships in influencing arthropod density. These findings highlight, unprecedentedly, the equal importance of birds and bats in maintaining ecological balance across different strata of a temperate forest.

Papua New Guinea (PNG) has the greatest diversity of dacine fruit fly species (Diptera: Tephritidae: Dacinae) in the world, many of which are significant agricultural pests. Although their taxonomy is relatively well known, there is limited research on their geographical and elevational distribution. We undertook a survey of PNG's fruit fly fauna along a complete elevational gradient on Mt Wilhelm (175-3700 m a.s.l.) to determine the elevational species distribution and turnover of fruit fly communities. Fruit flies were sampled using a selection of male parapheromone lures, including Zingerone, a new and promising male attractant. In total, we collected 10 700 fruit flies representing 77 species. The total abundance and species richness of fruit flies decreased with increasing elevation. Species richness was similarly high at 175 and 200 m a.s.l. (30 and 27 species) and at 700 and 1200 m a.s.l. (16 and 20 species, respectively) but dropped suddenly to only two species at 1700 m a.s.l. and to zero at all four sites above this elevation. There were no flies attracted exclusively to Zingerone. One species (Bactrocera recurrens) exhibited dramatic, temporal changes in abundance during the study period. Fruit fly assemblages were significantly influenced by both the lure type and elevation. Similarity of fruit fly communities decayed linearly with increasing elevational distance. We concluded that the upper limit of fruit fly distribution in PNG occurs between 1700 and 2200 m a.s.l. and the centre of diversity occurs between 0 and 700 m a.s.l.

Elevational gradients affect the production of plant secondary metabolites through changes in both biotic and abiotic conditions. Previous studies have suggested both elevational increases and decreases in host-plant chemical defences. We analysed the correlation of alkaloids and polyphenols with elevation in a community of nine Ficus species along a continuously forested elevational gradient in Papua New Guinea. We sampled 204 insect species feeding on the leaves of these hosts and correlated their community structure to the focal compounds. Additionally, we explored species richness of folivorous mammals along the gradient. When we accounted for Ficus species identity, we found a general elevational increase in flavonoids and alkaloids. Elevational trends in non-flavonol polyphenols were less pronounced or showed non-linear correlations with elevation. Polyphenols responded more strongly to changes in temperature and humidity than alkaloids. The abundance of insect herbivores decreased with elevation, while the species richness of folivorous mammals showed an elevational increase. Insect community structure was affected mainly by alkaloid concentration and diversity. Although our results show an elevational increase in several groups of metabolites, the drivers behind these trends likely differ. Flavonoids may provide figs with protection against abiotic stressors. In contrast, alkaloids affect insect herbivores and may provide protection against mammalian herbivores and pathogens. Concurrent analysis of multiple compound groups alongside ecological data is an important approach for understanding the selective landscape that shapes plant defences.

The way arthropods are distributed vertically in tropical forests has been of great interest with diversity often greatest at or near the canopy top. Typically, stratification is measured up from the ground but, since the height of trees reaching the canopy top can vary, we hypothesise that distance down from the canopy top, might better explain arthropod distributions. To test this samples were collected from Australian tropical rainforest trees in both dry and wet seasons by beating foliage from five trees for each of 11 tree species at set intervals down each tree. A total of 2628 arthropods were collected. Abundant groups were Araneae, Coleoptera, Formicidae, Blattodea and Homoptera. Coleoptera were sorted to species. Since the forest was naturally disturbed by storms, height of trees reaching the canopy top ranged 10–40 m. Our results suggested that the best fit for vertical stratification, either distance from ground or distance down from the canopy, were taxon specific. For ordinal richness and abundance of arthropods the best model was distance from the ground with decreasing trends from the ground. Similarly, distance from the ground best fitted abundances of spiders, cockroaches and Homoptera. In contrast, declination from the canopy top best fitted beetle species richness and abundance, and ant abundance. The effect of vertical stratification was, however, significant only for ants in dry season: abundance of ants decreased with increasing distance down from the canopy top. We were surprised to have found taxon-specific patterns, which may be explained by highly variable canopy tree height, creating vertically heterogeneous micro-habitat conditions in this forest system.

Classic research on elevational gradients in plant-herbivore interactions holds that insect herbivore pressure is stronger under warmer climates of low elevations. However, recent work has questioned this paradigm, arguing that it oversimplifies the ecological complexity in which plant-insect herbivore interactions are embedded. Knowledge of antagonistic networks of plants and herbivores is however crucial for understanding the mechanisms that govern ecosystem functioning. We examined herbivore damage and insect herbivores of eight species of genus Ficus (105 saplings) and plant constitutive defensive traits of two of these species, along a rain forest elevational gradient of Mt. Wilhelm (200-2,700 m a.s.l.), in tropical Papua New Guinea. We report overall herbivore damage 2.4% of leaf area, ranging from 0.03% in Ficus endochaete at 1,700 m a.s.l. to 6.1% in F. hombroniana at 700 m a.s.l. Herbivore damage and herbivore abundances varied significantly with elevation, as well as among the tree species, and between the wet and dry season. Community-wide herbivore damage followed a hump-shaped pattern with the peak between 700 and 1,200 m a.s.l. and this pattern corresponded with abundance of herbivores. For two tree species surveyed in detail, we observed decreasing and hump-shaped patterns in herbivory, in general matching the trends found in the set of plant defenses measured here. Our results imply that vegetation growing at mid-elevations of the elevational gradient, that is at the climatically most favorable elevations where water is abundant, and temperatures still relatively warm, suffers the maximum amount of herbivorous damage which changes seasonally, reflecting the water availability.

Much of the world's insect and plant biodiversity is found in tropical and subtropical ‘hotspots’, which often include long elevational gradients. These gradients may function as ‘diversity pumps’ and contribute to both regional and local species richness. Climactic conditions on such gradients often change rapidly along short vertical distances and may result in local adaptation and high levels of population genetic structure in plants and insects. We investigated the population genetic structure of two species of Ficus (Moraceae) along a continuously forested elevational gradient in Papua New Guinea. This speciose plant genus is pollinated by tiny, species‐specific and highly coevolved chalcid wasps (Agaonidae) and represented by at least 73 species at our study gradient. We present results from two species of Ficus sampled from six elevations between 200 m and 2700 m a.s.l. (almost the entire elevational range of the genus) and 10 polymorphic microsatellite loci. These results show that strong barriers to gene flow exist between 1200 m and 1700 m a.s.l. Whereas lowland populations are panmictic across distances over 70 km, montane populations can be disjunct over 4 km, despite continuous forest cover. We suggest that the limited gene flow between populations of these two species of montane Ficus may be driven by environmental limitations on pollinator or seed dispersal in combination with local adaptation of Ficus populations. Such a mechanism may have wider implications for plant and pollinator speciation across long and continuously forested elevational gradients if generalist insect pollinators and vertebrate seed dispersers also form populations based on elevation.

How arthropods are distributed within the vertical structure of tropical rainforests is of considerable interest to ecologists. Here, we examine how light trapped beetles are distributed in tropical rainforest in North Queensland, Australia. In January and July 2012, traps were suspended 0m, 10m, 20m and 30m above the ground in five locations with no more than one trap at any single location on any night. Maximum canopy height at the sites was 35m. A total of 7299 individuals of 492 morphospecies and 66 families were collected. The species abundance-based coverage estimator predicted a total species richness of 765. Sample completeness decreases with increasing height from the ground suggesting higher strata were less well sampled. Distance-based redundancy analysis showed species richness was significantly different between 30m and all other levels but not between other paired strata. In contrast, both species composition and family composition were significantly distinct for all strata pairs except 10m with 20m, and 20m with 30m, suggesting that the most distinct strata were 0m and 30m. The first two axes of ordination and hierarchical clustering accounted for 46.5% and 17.4% of species composition variation corresponding with season and stratum, respectively. Family level analyses gave similar results to those at the species level. We found stratification of different feeding guilds with herbivores comprising a larger percentage of species in higher strata, whereas saprophages were restricted to the lower strata, reflecting the availability of key resources for these guilds. Fewer species or families were found to be indicators of strata, as measured using IndVal, than for Malaise and flight interception traps (FIT). Dytiscidae and Hydraenidae were abundant but had not been collected using Malaise and FIT. Which species or families are indicators of strata depends on sampling method suggesting multiple sampling methods should be used to establish indicators.

We introduce a novel framework for conceptualising, quantifying and unifying discordant patterns of species richness along geographical gradients. While not itself explicitly mechanistic, this approach offers a path towards understanding mechanisms. In this study, we focused on the diverse patterns of species richness on mountainsides. We conjectured that elevational range midpoints of species may be drawn towards a single midpoint attractor - a unimodal gradient of environmental favourability. The midpoint attractor interacts with geometric constraints imposed by sea level and the mountaintop to produce taxon-specific patterns of species richness. We developed a Bayesian simulation model to estimate the location and strength of the midpoint attractor from species occurrence data sampled along mountainsides. We also constructed midpoint predictor models to test whether environmental variables could directly account for the observed patterns of species range midpoints. We challenged these models with 16 elevational data sets, comprising 4500 species of insects, vertebrates and plants. The midpoint predictor models generally failed to predict the pattern of species midpoints. In contrast, the midpoint attractor model closely reproduced empirical spatial patterns of species richness and range midpoints. Gradients of environmental favourability, subject to geometric constraints, may parsimoniously account for elevational and other patterns of species richness.

To model the diverse patterns of species richness patterns on mountainsides, we conjectured that a unimodal gradient of environmental favorability— spanning the elevational domain but not necessarily centered on it— may interact with geometric constraints imposed by sea level and the mountaintop to produce taxon-specific patterns of species richness.. We developed a Bayesian simulation model to estimate the location and strength of such a midpoint attractor.. We also constructed midpoint predictor models to test whether environmental variables could directly account for the observed patterns of species range midpoints...We challenged these models with 16 elevational datasets, comprising 4500 species of insects, vertebrates, and plants. Whereas the midpoint predictor models generally failed to match the pattern of species midpoints, the midpoint attractor model closely reproduced empirical spatial patterns of species richness and range midpoints.. Gradients of environmental favorability, subject to geometric constraints, may parsimoniously account for elevational patterns of species richness.

In an intensive mark‐release‐recapture study of all butterfly species in a tropical rainforest understory, 5903 individuals from 90 butterfly species (from the estimated total of 104 ± 9 species present in understory habitat) were marked, and 1308 recaptured at least once. The study proved that mark‐recapture methods are feasible in tropical rainforests, but also showed its limitations, as after 232 person‐days of sampling we could only characterise dispersal for one‐third of the species present. The mean dispersal distance was 184 ± 46.1 m per species, while for six of the 14 species studied >1% of individuals were estimated to disperse 1 km or more. These parameters are, however, strongly dependent on the size and spatial configuration of the study plots, particularly in large homogeneous habitats. A new method proposed here to correct this bias revised the mean distance between two captures from 135 ± 33.6 to 325 ± 87.0 m per species. These results, in combination with data from large permanent rainforest plots, suggest that most woody plant species in tropical forests are sufficiently abundant to serve as host plant species even to monophagous Lepidoptera species.

. 1.Standardised transect counts of butterflies in old-growth rainforests in different biogeographical regions are lacking. Such data are needed to mitigate the influence of methodological and environmental factors within and between sites and, ultimately, to discriminate between long-term trends and short-term stochastic changes in abundance and community composition. 2.We compared butterfly assemblages using standardised Pollard Walks in the understory of closed-canopy lowland tropical rainforests across three biogeographical regions: Barro Colorado Island (BCI), Panama; Khao Chong (KHC), Thailand; and Wanang (WAN), Papua New Guinea. 3.The length and duration of transects, their spatial autocorrelation, and number of surveys per year represented important methodological factors that strongly influenced estimates of butterfly abundance. Of these, the effect of spatial autocorrelation was most difficult to mitigate across study sites. 4.Butterfly abundance and faunal composition were best explained by air temperature, elevation, rainfall, wind velocity, and human disturbance at BCI and KHC. In the absence of weather data at WAN, duration of transects and number of forest gaps accounted for most of the explained variance, which was rather low in all cases (<33%). 5.Adequate monitoring of the abundance of common butterflies was achieved at the 50ha BCI plot, with three observers walking each of 10 transects of 500m for 30min each, during each of four surveys per year. These data may be standardised further after removing outliers of temperature and rainfall. Practical procedures are suggested to implement global monitoring of rainforest butterflies with Pollard Walks.

Human modification of pristine habitats almost always leads to the local extinction of a subset of the species present. This means that the ecosystem processes carried out by the remaining species may change. It is well documented that particular species of ants carry out important ecosystem processes. However, while much work has been carried out to investigate the link between biodiversity and ecosystem functioning in other taxa, this has received relatively little attention for ant communities. In particular, no attempt has been made to link levels of ant diversity with the rates of nutrient redistribution carried out by scavenging species. Here we investigate the impacts of anthropogenic disturbance on the rate of scavenger-mediated nutrient redistribution, using bait-removal rate as a surrogate measure. We found that although ant species richness, diversity, biomass and rates of bait removal did not change systematically across the disturbance gradient, the rate of bait removal was related to ant species richness. Sites with more ant species experienced a faster rate of bait removal. This is the first documented positive relationship between ant species richness and the rate of an ecosystem process. If these results are applicable at larger spatial scales for a wider range of nutrient sources, loss of ant species could lead to important changes in the way that ecosystems function.

Insects, like most odter organisms, are more diverse in tropical than in temperate regions, but standardized comparisons of diversity among tropical regions are rare.Disentangling the effects of ecological, evolutionary, and biogeographic factore on community diversity requires standardized protocols and long-term studies.We compared the abundance and diversity of butterflies using standardised 'Pollard walk' transect counts in die understory of closed-canopy lowland rainforests in Panama (Barro Colorado Island, BCI), Thailand (Khao Chong, KHC) and Papua New Guinea (Warning, WAN).We observed 1792, 1797 and 3331 butterflies representing 128,131 and 134 species during 230,231 and 120 transects at BCI, KHC and WAN, respectively.When corrected for length and duration of transects, butterfly abundance and species richness were highest at WAN and KHC, respecuvely.Although high butterfly abundance at WAN did not appear to result from methodological artefacts, the biological meaning of this observation remains obscure.The WAN site appeared as florisdcally diverse as KHC, but supported lower butterfly diversity.This emphasizes that factors odier than plant diversity, such as biogeographic history, may be cnicial for explaining butterf ly diversity.The KHC butterfly fauna may be unusually species rich because the site is at a biogeographic crossroads between the Indochinese and Sundaland regions.In contrast, WAN is firmly widiin the Australian biogeographic region and relatively low species numbers may result from island biogeograpbic processes.The common species at each of the three sites shared several traits: fruit and nectar feedeis were equally represented, more than half of common species fed on eidter epiphytes or lianas as larvae, and their range in wing sizes was similar.These observations suggest that Pollard walks in different tropical rainforests target similar assemblages of common species, and, hence, represent a useful tool for long-term monitoring of rainforest butterfly assemblages.

Until now the altitudinal factor has not been taken into account to estimate tropical arthropod diversity. The ultimate aim of the terrestrial biodiversity survey “Our Planet Reviewed – Papua New Guinea” was to estimate biological diversity generated by altitudinal turnover of arthropod species. It took place on Mount Wilhelm, Papua New Guinea highest peak (4509 m a.s.l.), and one of the few equatorial mountains outside the Andes left with a continuous undisturbed forest from the sea level all the way to the timber line limit. An unprecedented sampling effort was concentrated over 16 days in 2012 with a semi-simultaneous sampling at eight different elevations (every 500 m from 200 m to 3700 m a.s.l.). Arthropods were collected with various methods: flight interception traps (targeting Coleoptera), Malaise traps (targeting Hymenoptera, Diptera and Hemiptera), Steiner traps (targeting tephritid flies), beating of the understorey vegetation, and insecticide spraying on tree barks (various groups targeted). A botany survey was conducted at each elevation to characterize vegetation. An additional site, Wanang, was sampled according to the same protocol, as replicated lowland site. Our team combined international experts with local postgraduate students, para-ecologists and villagers. Arthropod samples collected during the biotic survey were pre-sorted in Papua New Guinea and forwarded to taxonomists worldwide. The current book presents the first taxonomic results of the biotic survey. Project outputs included not only species discovery, but also direct financial benefits to landowner communities, raised profile of conservation areas, training of paraecologists and postgraduate students, education programmes and, finally, crucial biodiversity information needed for ecological analyses and conservation management. RÉSUMÉ Module terrestre de “La Planète Revisitée Papouasie-Nouvelle-Guinée” : buts, méthodes et premiers résultats taxonomiques. Jusqu’à présent le facteur altitudinal n’a pas été pris en compte dans les estimations du nombre global d’arthropodes dans les milieux tropicaux. Le but ultime de l’inventaire de biodiversité terrestre “La Planète Revisitée Papouasie Nouvelle Guinée” est d’estimer la diversité biologique générée par le renouvellement altitudinal des espèces. Cet inventaire a pris place au Mont Wilhelm, le plus haut pic de Papouasie Nouvelle Guinée (4509 m), et l’une des rares montagnes, en dehors des Andes, encore couverte de forêt depuis le niveau de la mer jusqu’à la limite de distribution des arbres. Un effort d’échantillonnage sans précédent a été concentré sur 16 jours en 2012 avec des récoltes semi-simultanées à huit altitudes (tous les 500 m, de 200 à 3700 m). Les arthropodes ont été récoltés par différentes méthodes: des pièges d’interception (visant les coléoptères), des pièges Malaise (pour les hyménoptères, diptères et hémiptères), des pièges Steiner (pour les mouches téphritides), du battage de la végétation de sous-bois et de la fumigation d’insecticide sur les écorces d’arbres (récoltant une multitude de groupes). De plus, un inventaire botanique a été conduit à chaque altitude pour caractériser la végétation. Un site supplémentaire de basse altitude, Wanang, a été également échantillonné selon le même protocole, à titre de réplicat. Notre équipe était composée d’experts internationaux associés à des étudiants, des paraécologistes et des villageois. Les échantillons d’arthropodes récoltés durant l’inventaire de biodiversité ont été pré-triés en Papouasie-Nouvelle-Guinée et envoyés à des taxonomistes dans le monde entier. Le présent ouvrage présente les premiers résultats taxonomiques de l’expédition. Les résultats du projet incluent non seulement la découverte de nouvelles espèces, mais aussi le soutien financier aux communautés locales propriétaires des sites échantillonnés, la mise en valeur des aires protégées, la formation de paraécologistes et d’étudiants, l’éducation du public et, finalement, le rassemblement de données de biodiversité cruciales pour les analyses écologiques et la conservation des milieux. INTRODUCTION One of the main aims of the “Our Planet Reviewed” initiative is to document both terrestrial and marine biodiversity in some of the most biodiverse and least explored areas of the planet. This initiative results from the collaboration between a team of marine biologists led by Philippe Bouchet, Muséum national d’Histoire naturelle (MNHN, France), and Olivier Pascal, coordinator of numerous terrestrial expeditions involving the canopy raft [“Radeau des Cimes”, an inflatable platform laid down on the top of the forest canopy] and the IBISCA (Investigating the Biodiversity of Soil and Canopy Arthropods) expert network (Basset et al. 2007; Leponce et al. 2012). Previous expeditions have been conducted in 2006 in Vanuatu (SANTO2006 project, Bouchet et al. 2009, 2012; Corbara 2009) and in 2009-2010 in Mozambique/Madagascar (Clarke 2011, Pascal 2011). Typically, these scientific expeditions gather a large number of participants. In SANTO 2006, a total of 233 persons (23 nationalities) were involved, comprising 155 scientists, 20 media participants (journalists, film makers, photographers, observers) and a support staff of 58 persons (managers, technicians, logistics support). In Mozambique/Madagascar, 155 persons (19 nationalities) participated to the project: 109 scientists, 22 media participants and a support staff of 24 persons. Our Planet reviewed – PaPua new Guinea 15 Papua New Guinea (PNG) was an obvious choice for a new project. The island of New Guinea is the largest and highest tropical island. New Guinea is situated within the coral triangle and its marine biodiversity is exceptional (Veron et al. 2009). PNG is also the third largest remaining block of tropical forest, after the Amazon and Congo basins. The synergistic actions of equatorial climate, insular situation and complex orogeny have resulted in extremely rich terrestrial fauna and flora (Gressitt 1982; Barthlott et al. 2005; Marshall & Beehler 2007; Mutke et al. 2011; Toussaint et al. 2014). Plant richness is very high, estimated at between 15 and 20 thousand species, over 70% of them endemic (Davis et al. 1995). Davis et al. (1995) also estimated that there should be 5,000-6,000 plant species within an area of 9000 km2 around Mt Wilhelm, Papua New Guinea’s highest mountain (4509 m a.s.l.). Apart from its extraordinary biodiversity, Papua New Guinea presented two key advantages for the terrestrial module project. First, PNG is one of the few places left where one can find complete elevational gradients in equatorial forests, from sea level up to the tree line. In many other places lowlands are heavily disturbed by human activities, or the mountains do not reach the tree line. Second, a large-scale study was feasible thanks to the presence of a leading paraecologist/ parataxonomist research center, the New Guinea Binatang Research Center (BRC) led by Prof. Vojtech Novotny (Schmiedel et al. 2016). Parataxonomists and paraecologists are local technicians, generally hired from local communities but sometimes also new university graduates in biology (Janzen 2004, Basset et al. 2004, Schmiedel et al.2016). They were trained by professional taxonomists or ecologists. The additional workforce of paraecologists/parataxonomists allowed us to collect more biological samples and process them more efficiently. In PNG, parataxonomist training began in 1994 and led to the collection of major datasets on plant-herbivore food webs (Novotny et al. 2002, 2006, 2007, 2010). These datasets were used by Hamilton and colleagues (2010, 2013) to reassess the total number of tropical arthropods to between two and 7 million species. Another dataset collected in Panama by the IBISCA network allowed for the first time to evaluate the local arthropod diversity in a large (6,000 ha) patch of a local rainforest. The resulting estimate of approximately 25,000 species lives in a rainforest of the size of Manhattan (Basset et al. 2012). This study also suggested that tree diversity, which is far easier to determine, is a good predictor of the arthropod diversity. However a gap remains between the estimation of local and global arthropod diversity. We know too little about biodiversity at landscape-scale, where species composition changes along environmental gradients. Global estimates are based on lowland rainforests only and do not consider the rapid change in species composition along altitudinal gradients. This is a serious weakness since elevational gradients appear to be among the largest generators of species diversity, particularly in the tropics (Merckx et al. 2015). The ultimate aim of the Our Planet Reviewed terrestrial project in Papua New Guinea was to estimate, for the first time with such intense sampling effort, biological diversity generated by elevational turnover of arthropod species. Our approach was three-fold. First, we aimed to obtain, during an intense biotic survey, a global picture of the distribution of plant and selected arthropod groups along a complete elevational rainforest transect. Second, we studied in full detail the effects of plant diversity and abundance on insect diversity and abundance using a detailed census of plant-insect interactions within 0.2 ha forest plots in primary and secondary forest at 900 m asl. (to be compared with similar data from 100 and 1700 m a.s.l.). Third, using a model plant taxon with a large elevational distribution (Ficus, fig trees), we studied how herbivores of a particular plant species change with elevation and how they respond to change in their host plant species composition with elevation. We focus here on the main biotic survey during which we collected the species described in the next nineteen chapters of this book. We provide descriptions of study sites, sampling protocols, sample processing protocols and perspectives on the project.