Yams and megapode mounds in the lowland rain forest of Papua New Guinea

Kubo people of Papua New Guinea sometimes grew Dioscorea yams in mounds of forest litter that were made as egg-incubation sites by birds (Megapodiidae).' The small yam plots were included within larger banana gardens and, in the latter, it was yams, not bananas, that took precedence in the gardening decisions of people. The technique would be viable in the absence of a larger garden. It is interpreted as an expression of an ancient pattern of small-scale plant domestication.     

Gall‐forming insects in a lowland tropical rainforest: low species diversity in an extremely specialised guild

1. Gall‐forming insects are a guild of endophages that exhibit a high level of fidelity to their host plants, however, their level of host specificity is seldom explicitly tested. 2. Gall‐forming insect taxa from 32 species of woody tropical plants with resolved phylogenetic relationships were collected and reared, representing 15 families from all the major clades of angiosperms, at three lowland rainforest locations in Madang, Papua New Guinea (PNG). 3. More than 8800 galled plant parts were collected from 78 gall morphospecies at an average of 2.4 per host plant. Total species richness at the sampling sites was estimated to be 83–89. All but one morphospecies were monophagous resulting in an effective specialisation of 0.98. 4. Specific leaf weight, foliar nitrogen, the presence of latex, and the successional preference of plant species all gave a phylogenetic signal, but only plant successional preference influenced the species richness of galls on analysis of phylogenetically independent contrasts. Gall species were distributed randomly among host plant species and showed no preference for any particular plant lineage. Furthermore, most gall‐forming taxa were evenly dispersed across the host plant phylogeny. 5. In the tropical rainforests of New Guinea, gall‐forming insects are ubiquitous but occur in species‐poor assemblages. Local species richness is closely tied to the diversity of angiosperms owing to very high host specificity. 6. Finally, galler species richness data from the literature across habitats and latitudes were compared and suggest that tropical rainforests may be richer in galls than previously acknowledged.     

The importance of plant relatedness for host utilization among phytophagous insects

Current methods for measuring similarity among phytophagous insect communities fail to consider the phylogenetic relationship between host plants. We analysed this relation based on 3580 host observations of 1174 beetle species associated with 100 species of angiosperms in two different forest types in Panama. We quantified the significance of genetic distance as well as taxonomic rank among angiosperms in relation to species overlap in beetle assemblages. A logarithmic model describing the decrease in beetle species similarity between host-plant species of increasing phylogenetic distance explains 35% of the variation. Applied to taxonomic rank categories the results imply that except for the ancient branching of monocots from dicots, only adaptive radiations of plants on the family and genus level are important for host utilization among phytophagous beetles. These findings enable improvements in estimating host specificity and species richness through correction for phylogenetic relatedness between hosts and consideration of the host-specific fauna associated with monocots.     

Temporal variation in the influence of forest succession on caterpillar communities: A long‐term study in a tropical dry forest

Forest succession can influence herbivore communities through changes in host availability, plant quality, microclimate, canopy structure complexity and predator abundance. It is not well known, however, if such influence is constant across years. Caterpillars have been reported to be particularly susceptible to changes in plant community composition across forest succession, as most species are specialists and rely on the presence of their hosts. Nevertheless, in the case of tropical dry forests, plant species have less defined successional boundaries than tropical wet forests, and hence herbivore communities should be able to persist across different successional stages. To test this prediction, caterpillar communities were surveyed during eight consecutive years in a tropical dry forest in four replicated successional stages in Chamela, Jalisco and Mexico. Lepidopteran species richness and diversity were equivalent in mature forests and early successional stages, but a distinctive caterpillar community was found for the recently abandoned pastures. Species composition tended to converge among all four successional stages during the span of eight years. Overall, our results highlight the importance of both primary and secondary forest for the conservation of caterpillar biodiversity at a landscape level. We also highlight the relevance of long‐term studies when assessing the influence of forest succession to account for across year variation in species interactions and climatic factors. Abstract in French is available with online material.     

An altitudinal comparison of caterpillar (Lepidoptera) assemblages on Ficus trees in Papua New Guinea

Aim This analysis of caterpillar (Lepidoptera) beta‐diversity between tropical lowlands and highlands attempts to separate the effects of between‐site (1) turnover of herbivore species on particular host plants, (2) changes in host use by herbivores, and (3) turnover of plant species on changes in herbivore assemblages. Location Two rain forest areas 130 km and 1700 altitudinal metres apart were studied in Papua New Guinea: one in the lowlands (100 m a.s.l.) on the northern coast of the island and one in the central New Guinean cordillera at 1800 m a.s.l. Methods The analysis is based on caterpillar feeding records obtained by quantitative sampling and rearing of caterpillars from four Ficus species studied in the mountains and 21 Ficus species and 62 plant species from other genera and families studied in the lowlands, including three Ficus species studied in both areas. Results Only 17% of species feeding on Ficus in the highlands also occurred in the lowlands. These species represented 1–46% of individuals in caterpillar assemblages on particular Ficus hosts. Widespread species included both Ficus specialists and generalists feeding on numerous plant families. Some of the Ficus specialists changed their preferred host species with altitude. High species turnover was not explained by changes in the species composition of host plants with altitude as lowland and montane assemblages feeding on the same Ficus species showed high turnover. Despite the rarity of widespread caterpillars, the lowland and montane Ficus assemblages were remarkably similar in their dominance structure, species richness, host specificity, generic composition and familial composition. Main conclusions Ficus‐feeding Lepidoptera assemblages between tropical lowlands and highlands are characterized by substantial species turnover not explained by altitudinal changes in the composition of the vegetation. Further, species‐rich plant genera can support caterpillar assemblages with relatively low beta‐diversity compared with species‐poor genera as caterpillars can switch their host preferences from one congeneric host species to another along an altitudinal gradient. Closely related plant species can thus represent a broad, continuously distributed resource along such gradients.     

Species Richness,Forest Structure,and Functional Diversity During Succession in the New Guinea Lowlands

Much of the world's tropical forests have been affected by anthropogenic disturbance. These forests are important biodiversity reservoirs whose diversity, structure and function must be characterized across the successional sequence. We examined changes in structure and diversity along a successional gradient in the lowlands of New Guinea. To do this, we measured and identified all stems ≥5 cm diameter in 19 0.25 ha plots ranging in age from 3 to >50 yr since disturbance. We also measured plant functional traits related to establishment, performance, and competitive ability. In addition, we examined change in forest structure, composition, species diversity, and functional diversity through succession. By using rarefaction to estimate functional diversity, we compared changes in functional diversity while controlling for associated differences in stem and species density. Basal area and species density increased with stand age while stem density was highest in intermediate secondary forests. Species composition differed strongly between mature and secondary forests. As forests increased in basal area, community‐weighted mean wood density and foliar carbon increased, whereas specific leaf area and proportion of stems with exudate decreased. Foliar nitrogen peaked in medium‐aged forests. Functional diversity was highest in mature forests, even after accounting for differences in stem and species diversity. Our study represents one of the first attempts to document successional changes in New Guinea's lowland forest. We found robust evidence that as succession proceeds, communities occupy a greater range of functional trait space even after controlling for stem and species density. High functional diversity is important for ecological resiliency in the face of global change.     

Species richness and assemblages of bats along a forest elevational transect in Papua New Guinea

Over the past decades, elevational gradients have become a powerful tool with which to understand the underlying cause(s) of biodiversity. The Mt. Wilhelm elevational transect is one such example, having been used to study the birds, insects, and plants of Papua New Guinea (PNG). However, a survey of mammals from this forest elevational transect was lacking. We thus aimed to investigate patterns in the community structure and species richness of bats (Chiroptera) along the transect, link the species to available regional data, and explain the observed patterns by including environmental characteristics. Bat assemblages were surveyed between 200 m and a timberline at 3700 m a.s.l. at eight study sites separated by 500 m in elevation. We conducted mist-netting and acoustic surveys to detect and identify species at each site. Regional data were compiled to compare local with regional diversity. Finally, biotic (i.e., food availability, habitat features) and abiotic (i.e., mean daily temperature) factors were included in our analyses to disentangle the ecological drivers underlying bat diversity. Results revealed that species richness decreases with ascending elevation and was best explained by a corresponding decrease in temperature. We observed both turnover and nestedness of the species composition at regional scale whereas turnover was dominant at local scale. Extensions and shifts of bat elevational ranges were also found in Mt. Wilhelm. Consequently, despite that the study was restricted to one mountain in PNG, it demonstrates how basic inventory surveys can be used to address ecological questions in other similar and undisturbed tropical mountains.     

Caprellids (Crustacea: Amphipoda) from Papua New Guinea,with the description of a new species

This is the first study of caprellid amphipods from the coast of Papua New Guinea. Several collections from Madang Lagoon (north) and Bootless Bay (south) have been studied. Seven species in seven genera are recorded, of which Pseudoproto papua sp. nov. is described as new to science. The genus Pseudoproto Mayer, 1903 has consisted, so far, of only one species, Pseudoproto fallax Mayer, 1903. Although only a single male has been found of Pseudoproto papua sp. nov., differences in antennae, mouthparts, gnathopod 2 and pereopods 3 and 4 have revealed that it represents a new species of Pseudoproto. Lateral view figures of all species, together with a key to species level for the Caprellidea from Papua New Guinea are also included. Communicated by H.-D. Franke     

Colonising aliens: caterpillars (Lepidoptera) feeding on Piper aduncum and P. umbellatum in rainforests of Papua New Guinea

Abstract.  1. Caterpillar assemblages feeding on two alien plants, Piper aduncum and P. umbellatum , were studied in lowland rainforest in Papua New Guinea and compared with assemblages from 69 species of native woody hosts, including congeneric P. macropiper .
2. Species richness of caterpillars feeding on P. aduncum (29 species per 1500 m² of foliage) and P. umbellatum (36 species) was higher than the median richness for the 69 native hosts (23 species).
3. The probability that a caterpillar species colonised alien Piper increased with its host range from 3% for the species feeding on a single plant family to 92% for the species with host range >10 plant families.
4. The assemblage on P. aduncum was dominated by a single species ( Herpetogramma sp. near licarsisalis , Crambidae), which represented 48% of individuals, and also had a high proportion (34%) of rare species, collected as single individuals. This community structure was indistinguishable from that of a typical native host. In contrast, the P. umbellatum assemblage was unusual as no species represented >10% of individuals.
5. The aggressive invasion by P. aduncum of early successional vegetation is not explained by a competitive advantage due to low herbivore load, as the abundance of caterpillars feeding on it was comparable to that of native pioneer plants.
6. The caterpillar assemblage on P. aduncum demonstrated that an assemblage indistinguishable from native assemblages in density, species richness, and dominance structure (but not in host specificity) can originate from the existing species pool in lowland rainforests on a recently established tree species in <50 years.     

An alien in an archipelago: Spathodea campanulata and the geographic variability of its moth (Lepidoptera) communities in the New Guinea and Bismarck Islands

Aim This analysis of moth (Lepidoptera) communities colonizing an alien tree invading secondary rain forest vegetation in Melanesia examines the predictability of insect herbivorous communities across distances of tens to thousands of km and the effect of dispersal barriers on community composition in the tropics. Location Six secondary rain forest sites were studied within four equidistant yet distinct geographic areas of the New Guinea mainland and the Bismarck Archipelago, including two watershed areas (Madang and Sepik) on mainland New Guinea and the adjacent large island of New Britain and small island of Unea. Methods The analysis is based on feeding records obtained by quantitative sampling and rearing of caterpillars from the alien host Spathodea campanulata (Bignoniaceae). It examines the variation in Lepidoptera community composition at six study sites distributed on three adjacent islands ranging in size from 30 to 865,000 km². Results Spathodea campanulata was colonized by 54 folivorous species of Lepidoptera. Most of them were generalists, feeding on > 1 native plant family. However, the three most abundant species representing 83% of all individuals (Acherontia lachesis, Hyblaea puera complex and Psilogramma menephron) were relatively host specific, feeding predominantly on a single native family that is not the Bignoniaceae. Most of the 23 species analysed in detail had a wide geographic distribution, including 13 species spanning the entire 1000‐km study transect. While the Lepidoptera in two New Guinea areas 280 km apart were similar to each other, there was a discontinuity in species composition between New Guinea and the smaller islands. However, no negative effect of small islands on species richness was detected. Main conclusions Spathodea campanulata was rapidly colonized by folivorous Lepidoptera communities with species richness and dominance structure indistinguishable from the assemblages feeding on native hosts, despite its phylogenetic isolation from the native vegetation. Although most species were generalists, the highest population densities were reached by relatively specialized species, similar to the communities on native hosts. The species turnover across distances from 10 to 1000 km was relatively low as most of the species had wide geographic ranges.     

Insect herbivory and herbivores of Ficus species along a rain forest elevational gradient in Papua New Guinea

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.     

Local versus regional species richness in tropical insects: one lowland site compared with the island of New Guinea

1. The overlap in species composition of Cercopoidea (Aphrophoridae, Cercopidae, and Machaerotidae), Flatidae, and Ricaniidae between two data sets, an almost exhaustive census from 13 Ficus species and a sample from diverse vegetation in the same area, led to the estimate for local species richness of 111 (SE 11.5) species (45 species of Cercopoidea, 36 species of Flatidae, and 30 species of Ricaniidae) at a lowland rainforest site in New Guinea. 2. Samples restricted to 13 species of Ficus contained 66 species, i.e. 59% of the estimated local species richness. This high proportion probably results from the high proportion of polyphagous and tourist (transient) species in the Cercopoidea, Flatidae, and Ricaniidae. 3. The two largest museum collections of New Guinean insects contained 327 species of Cercopoidea from New Guinea, including 23 of the 34 species collected in the field samples. This overlap led to the estimate of 483 (SE 97.2) species of Cercopoidea present in New Guinea. 4. The species found in the field samples were also 2.6 times more likely to be found in the museum collection than other species. This sampling bias can be due to a positive correlation between species local abundance and geographic distribution and/or similar patterns of species abundance at different sites. 5. The estimate of species richness of Cercopoidea in New Guinea increased to 1222 species when corrected for this sampling bias. Thus, only 4% of the New Guinean species were present locally, in the study area. Such high beta diversity is probably a consequence of the exceptional habitat and vegetation diversity in New Guinea, as well as its complex geological history.     

Forest carbon in lowland Papua New Guinea: Local variation and the importance of small trees

Efforts to incentivize the reduction of carbon emissions from deforestation and forest degradation require accurate carbon accounting. The extensive tropical forest of Papua New Guinea (PNG) is a target for such efforts and yet local carbon estimates are few. Previous estimates, based on models of neotropical vegetation applied to PNG forest plots, did not consider such factors as the unique species composition of New Guinea vegetation, local variation in forest biomass, or the contribution of small trees. We analysed all trees >1 cm in diameter at breast height (DBH) in Melanesia's largest forest plot (Wanang) to assess local spatial variation and the role of small trees in carbon storage. Above‐ground living biomass (AGLB) of trees averaged 210.72 Mg ha^?1 at Wanang. Carbon storage at Wanang was somewhat lower than in other lowland tropical forests, whereas local variation among 1‐ha subplots and the contribution of small trees to total AGLB were substantially higher. We speculate that these differences may be attributed to the dynamics of Wanang forest where erosion of a recently uplifted and unstable terrain appears to be a major source of natural disturbance. These findings emphasize the need for locally calibrated forest carbon estimates if accurate landscape level valuation and monetization of carbon is to be achieved. Such estimates aim to situate PNG forests in the global carbon context and provide baseline information needed to improve the accuracy of PNG carbon monitoring schemes.     

Mesophyll cell‐sucking herbivores (Cicadellidae: Typhlocybinae) on rainforest trees in Papua New Guinea: local and regional diversity of a taxonomically unexplored guild

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Crowds,Affect, and the Mediation of Emergent Collectivities: A Student Strike in Papua New Guinea as an Order-Making Project

ABSTRACT

From the institutional perspective of a university, student strikes mark a time of heightened disorder. In this contribution, I turn this perspective around and analyse a student strike at the University of Goroka in the Papua New Guinea highlands as an order-making project instead. The observed student strike established an alternative regime among students, which was reinforced through a sense of having achieved a superior sophistication of order through the effective, and affective, alignment of minds and bodies into a single entity. Placing the achievement of collective unity in relation to what appears as Melanesian notions of order on one hand, and recent re-evaluations of the psychology of crowds within anthropology and sociology on the other hand, I explore conceptual connections in the work of ‘mediation’ between order making in Melanesia and contemporary (critiques of) affect theory.