Litter-dwelling Species Research Articles

Are there different trophic niches of enchytraeids? A stable isotopic (δ13C, δ15N) evidence

Enchytraeids, also known as pot worms, represent one of the least studied groups of soil mesofauna. These organisms can be found throughout the globe from coasts to deserts reaching high densities and biomass, but their specific roles within the soil food web remain a stark knowledge gap. Enchytraeid species are involved in belowground trophic interactions, which could be distinguished by their morphological characteristics and ecological traits. To quantify this, we analyzed stable isotopes δ13C and δ15N in 16 enchytraeid species across various biomes and habitats in European Russia. Their isotopic niches were compared with different potential food sources and other soil invertebrates. We found that the total δ13C and δ15N range by across single enchytraeid samples reached 8 and 11‰, and isotopic niche of species depends on soil stratification and is reflected in the chaeta number per bundle, and, to a lesser extent, on the size or genera identity. These findings enabled us to split enchytraeids into three guilds within the functional group of secondary decomposers: (i) epigeic – that include litter-dwelling species that predominantly feed on plant material but also can ingest microorganisms; (ii) epi-endogeic – inhabiting upper humified soil and F-litter horizons, and feed primarily on various saprotrophic microorganisms; (iii) endogeic – consuming old processed humified and dissolved organic matter in lower H-horizon and even mineral A-horizons beneath. Our results are an important step forward in integrating enchytraeids into the next-generation food web models, not as a single black box, but as multiple blocks delivering different functions.

High sensitivity to dietary imidacloprid exposure in early life stages of Folsomia quadrioculata (Collembola) populations from contrasting climates

Survival of early life stages is critical for population growth. Understanding the vulnerability of these sensitive stages can therefore improve ecological risk predictions. The globally-used neonicotinoid insecticide imidacloprid does not degrade easily in soil and occurs at concentrations potentially toxic to non-target soil organisms, such as Collembola. Here, we studied the effects of dietary exposure to imidacloprid on the survival of juveniles in an arctic and a temperate population of Folsomia quadrioculata (Collembola), a commonly-occurring litter-dwelling species in the Northern Hemisphere. The exposure lasted from <24 h to 30 days since hatching at 15 °C. We assessed whether (1) the arctic population of the test species with faster development rates could be more vulnerable than the temperate population, (2) cumulative mortality could increase substantially with exposure time, and (3) the mortality risk experienced during the juvenile stage could be greater than that experienced by the adults. We found a strong concentration-dependent decline in survival in both populations, with small but significantly different LC50s, despite large differences in multiple life-history traits. Applying a General Unified Threshold model for Survival (GUTS) showed a low threshold for effects, slow damage dynamics, a 6–11-fold decrease in LC50 from 14 to 30 days of exposure, and saturation of damage at the three highest concentrations. In addition, exposure starting soon after hatching caused much more mortality than that starting in the adult stages. Our findings suggest that toxicity tests not emphasizing the neonate stages or not lasting long enough can underestimate the implications for populations of naturally abundant non-target organisms.

The hidden diversity and inland radiation of Sri Lanka’s ground-dwelling geckos of the genus Cyrtodactylus (Reptilia: Gekkonidae)

The genus Cyrtodactylus has recently been classified phylogenetically into several clades, subclades, groups, and some into Sri Lankan Cyrtodactylus. Certain complexes from the Indian subcontinent have been assigned to the “C. triedrus group”. This group is comprised of medium-sized species (SVL 50.6–105.7 mm) and are composed of five major species complexes: fraenatus, triedrus, deccanensis, jeyporensis, and collegalensis. Among these complexes, the latter four are composed of ground and litter dwelling species, which were previously assigned to the genus Geckoella; and is currently being treated as a subgenus. Cyrtodactylus triedrus, an endemic species of Sri Lanka, has long been considered a widely distributed single species in this part of the world. Based on morphological and phylogenetic evidences, we demonstrate that C. (G.) triedrus is not a single species, but a species complex. We also describe a new species that is restricted to intermediate savanna-mixed dry lowland forested habitats. Furthermore, we resurrect Geckoella punctata, assign it to the genus Cyrtodactylus and designate a lectotype that we redescribe. The genetic divergence across species of the C. triedrus clade varies between 11–26% in the studied fragment of the mitochondrial NADH dehydrogenase subunit 2 gene. The molecular phylogeny of the ground dwelling radiation of the subgenus Geckoella indicates deep splits between the Indian species and Sri Lankan endemic C. (G.) triedrus sensu stricto, and between Indian dry and wet zone clades. Cyrtodactylus (G.). triedrus is restricted to the moist or submontane forests in the Central highlands of Sri Lanka and is redescribed herein based on its holotype. http://zoobank.org/urn:lsid:zoobank:org:pub:3B37037C-EE9F-4011-BEC9-47E1F3BB6779

Spatial and functional structure of an entire ant assemblage in a lowland Panamanian rainforest

Ants are a major ecological group in tropical rainforests. Few studies in the Neotropics have documented the distribution of ants from the ground to the canopy, and none have included the understorey. A previous analysis of an intensive arthropod study in Panama, involving 11 sampling methods, showed that the factors influencing ant β diversity (i.e., changes in assemblage composition) were, in decreasing order of importance, the vertical (height), temporal (season), and horizontal (geographic distance) dimensions. In the present study, we went one step further and aimed (1) to identify the best sampling methods to study the entire ant assemblage across the three strata, (2) to test if all strata show a similar horizontal β diversity and (3) to analyze the functional structure of the entire ant assemblage. We identified 405 ant species from 11 subfamilies and 68 genera. Slightly more species were sampled in the canopy than on the ground; they belonged to distinct sub-assemblages. The understorey fauna was mainly a mixture of species found in the other two strata. The horizontal β diversity between sites was similar for the three strata. About half of the ant species foraged in two (29%) or three (25%) strata. A single method, aerial flight interception traps placed alongside tree trunks, acting as arboreal pitfall traps, collected half of the species and reflected the vertical stratification. Using the functional traits approach, we observed that generalist species with mid-sized colonies were by far the most numerous (31%), followed by ground- or litter-dwelling species, either specialists (20%), or generalists (16%), and arboreal species, either generalists (19%) or territorially dominant (8%), and finally army ants (5%). Our results reinforce the idea that a proper understanding of the functioning of ant assemblages requires the inclusion of arboreal ants in survey programs.

Community structure of Lumbricidae in beech woodland of the Bieszczady National Park, Southeast Poland

As ecosystem engineers, earthworms play a key role in the soil environment. However, due to increasing anthropogenic pressure, soil organisms, including earthworms, are being threatened by habitat loss. In this study, we undertook a qualitative and quantitative investigation of earthworms of the family Lumbricidae in four types of Carpathian beech woodland (Fagetum carpaticum), characterized by their understory vegetation (I, F. c. festucetosum drymejae; II, F. c. typicum; III, F. c. lunarietosum; and IV, F. c. allietosum), in the Bieszczady National Park (Eastern Carpathians, Southeast Poland). At each investigated site, soil monoliths (25 cm × 25 cm × 25 cm) were examined by hand sorting. Earthworms were expelled from deep soil layers using a weak formalin solution (0.4%). Depending on the phytocoenosis, 7 species of Lumbricidae were identified at each of the sites I, II, and III and 10 at site IV. Site IV (F. c. allietosum) differed significantly (P < 0.05) from the other three sites with respect to earthworm biomass (59.71 ± 39.53 g m–2) and the Shannon-Wiener diversity index (0.52 ± 0.12). Although present three decades ago, the deep-burrowing species Octodrilus transpadanus and the litter-dwelling species Dendrobaena octaedra were not found at site IV in the present study. We suspect that these two species may have been displaced by the invasive Lumbricus terrestris, which was not found at the same site in the 1980s. Such observations warrant further investigation to verify the predicted effects of an invasive earthworm, including the potential effects on soils and other fauna and flora, which have been documented in numerous countries.

Anaxibia folia spec. nov.-a new litter-dwelling dictynid spider from India (Araneae: Dictynidae: Dictyninae).

The dictynid genus Anaxibia Thorell, 1898 currently has six nominal species distributed in the Oriental and Ethiopian regions (World Spider Catalog 2017). The genus represents tiny to small spiders characterised by a reduced cribellum, long, cylindrical anterior and posterior spinnerets, cymbium with caudal modification, palpal patella with dorsal horn, sub-apically arising embolus, conductor with wide lamellar apex and simple female genitalia (Lehtinen 1967). The genus has one representative in India: Anaxibia rebai (Tikader, 1966), originally described under Dictyna Sundevall, 1833 (Tikader 1966; Lehtinen 1967). In this paper, we describe and illustrate a new litter-dwelling Anaxibia species collected from the Kerala state of southern India.

Can you count on counting? Retrieving reliable data from non-lethal monitoring of micro-snails

Using non-lethal methods is especially important for the monitoring and conservation planning of endangered species and their habitats. The goal of this study is to check whether the current method of monitoring endangered micro-snail populations by soil sampling, which involves killing the snails and altering their microhabitat, could be replaced by a non-lethal method. The invasive and time-consuming soil sampling and analyzing is compared with searching the individuals by eye. Research was conducted in moist sedges meadows and seasonally inundated wetlands in western Poland and focused on two species of micro-snails differing in biology, i.e. Vertigo moulinsiana (a climbing species) and Vertigo angustior (a litter-dwelling species). Both vertiginid species are listed in the Annex II of the EU Habitat Directive and included in the IUCN Red List of Threatened Species. The results showed a significant correlation between the total number of individuals searched by eye and collected from soil samples of V. angustior and V. moulinsiana. Results of this study indicate that monitoring micro-snails by searching individuals by eye is feasible and may reduce further pressure of killing individuals of endangered species. Limitations of this method should however be taken into account – especially its inaccuracy in estimating the absolute abundance of the studied species.

Conservation at a slow pace: terrestrial gastropods facing fast-changing climate.

The climate is changing rapidly, and terrestrial ectotherms are expected to be particularly vulnerable to changes in temperature and water regime, but also to an increase in extreme weather events in temperate regions. Physiological responses of terrestrial gastropods to climate change are poorly studied. This is surprising, because they are of biodiversity significance among litter-dwelling species, playing important roles in ecosystem function, with numerous species being listed as endangered and requiring efficient conservation management. Through a summary of our ecophysiological work on snail and slug species, we gained some insights into physiological and behavioural responses to climate change that we can organize into the following four threat categories. (i) Winter temperature and snow cover. Terrestrial gastropods use different strategies to survive sub-zero temperatures in buffered refuges, such as the litter or the soil. Absence of the insulating snow cover exposes species to high variability in temperature. The extent of specific cold tolerance might influence the potential of local extinction, but also of invasion. (ii) Drought and high temperature. Physiological responses involve high-cost processes that protect against heat and dehydration. Some species decrease activity periods, thereby reducing foraging and reproduction time. Related costs and physiological limits are expected to increase mortality. (iii) Extreme events. Although some terrestrial gastropod communities can have a good resilience to fire, storms and flooding, an increase in the frequency of those events might lead to community impoverishment. (iv) Habitat loss and fragmentation. Given that terrestrial gastropods are poorly mobile, landscape alteration generally results in an increased risk of local extinction, but responses are highly variable between species, requiring studies at the population level. There is a great need for studies involving non-invasive methods on the plasticity of physiological and behavioural responses and the ability for local adaptation, considering the spatiotemporally heterogeneous climatic landscape, to allow efficient management of ecosystems and conservation of biodiversity.

Assimilation of plant-derived freshly fixed carbon by soil collembolans: Not only via roots?

Large amounts of freshly fixed carbon in forest ecosystems are allocated belowground and fuel soil food webs. This supply is usually generalized as the ‘root carbon’, but particular pathways by which freshly fixed carbon is assimilated by soil animals remain poorly understood. We followed the appearance of the isotopic label in springtails inhabiting different layers of soil and litter (euedaphic, hemiedaphic and epigeic life forms) after in situ pulse-labelling of spruce trees with 13CCO2. Isotopic label was most frequently observed in euedaphic Collembola (26% of all samples), mainly in Protaphorura armata. The label was very rare in litter-dwelling (hemiedaphic) species (4%). Surprisingly, the label was often observed in epigeic Collembola (11%). During the period of 44days after labelling, the proportion of labelled samples increased with time in euedaphic, but not in epigeic species, suggesting that freshly fixed carbon is assimilated by these collembolan groups via different pathways. Most likely, euedaphic species are trophically linked to plant roots, whereas epigeic species receive freshly fixed carbon from aboveground. The exact mechanisms and potential importance of the latter pathway should be evaluated in further research.

New leaf- and litter-dwelling species of the genus Pholcus from Southeast Asia (Araneae, Pholcidae)

We describe eight new species of the genus Pholcus, and document their microhabitats. Four species are assigned to the previously described Pholcus ethagala group: P. tanahrata Huber sp. nov., P. uludong Huber sp. nov., and P. bukittimah Huber sp. nov. from the Malay Peninsula, and P. barisan Huber sp. nov. from Sumatra. These species are all litter-dwellers that build domed sheet webs on the undersides of large dead leaves on the ground. The other four species are assigned to newly created species groups: the P. tambunan group with two species from northern Borneo: P. tambunan Huber sp. nov. and P. bario Huber sp. nov.; and the P. domingo group with two species from the Philippines, Mindanao: P. domingo Huber sp. nov. and P. matutum Huber sp. nov. These latter four species are leaf-dwellers that build barely visible silk platforms tightly attached to the undersides of live leaves. The main rationale for this paper is to provide part of the taxonomic and natural history background for upcoming phylogenetic and evolutionary (microhabitat shifts) analyses.

A new genus of ground and litter-dwelling pholcine spiders from Sarawak (Araneae, Pholcidae)

Two small, ground and litter-dwelling pholcid species from northern Borneo are described as representatives of a new genus, Hantu gen. nov.: H. kapit gen. et sp. nov. and H. niah gen. et sp. nov. Previous cladistic analyses suggested a closer relationship with the genera Savarna Huber, 2005 and Khorata Huber, 2005 (mainland Southeast Asia) than with the geographically closer genus Aetana Huber, 2005 (Borneo and Philippines to Fiji). Since the two species do not share any of the synapomorphies of Khorata and Savarna while having several synapomorphies on their own (ventral apophysis on male palpal coxa; male palpal trochanter apophysis with small teeth or scales; spines on male femora 1; high density of vertical hairs on male femora; presence of scape on epigynum), they are here proposed as representing a new genus.

Identifying Shifts in Leaf-Litter Ant Assemblages (Hymenoptera: Formicidae) across Ecosystem Boundaries Using Multiple Sampling Methods.

Global or regional environmental changes in climate or land use have been increasingly implied in shifts in boundaries (ecotones) between adjacent ecosystems such as beech or oak-dominated forests and forest-steppe ecotones that frequently co-occur near the southern range limits of deciduous forest biome in Europe. Yet, our ability to detect changes in biological communities across these ecosystems, or to understand their environmental drivers, can be hampered when different sampling methods are required to characterize biological communities of the adjacent but ecologically different ecosystems. Ants (Hymenoptera: Formicidae) have been shown to be particularly sensitive to changes in temperature and vegetation and they require different sampling methods in closed vs. open habitats. We compared ant assemblages of closed-forests (beech- or oak-dominated) and open forest-steppe habitats in southwestern Carpathians using methods for closed-forest (litter sifting) and open habitats (pitfall trapping), and developed an integrated sampling approach to characterize changes in ant assemblages across these adjacent ecosystems. Using both methods, we collected 5,328 individual ant workers from 28 species. Neither method represented ant communities completely, but pitfall trapping accounted for more species (24) than litter sifting (16). Although pitfall trapping characterized differences in species richness and composition among the ecosystems better, with beech forest being most species poor and ecotone most species rich, litter sifting was more successful in identifying characteristic litter-dwelling species in oak-dominated forest. The integrated sampling approach using both methods yielded more accurate characterization of species richness and composition, and particularly so in species-rich forest-steppe habitat where the combined sample identified significantly higher number of species compared to either of the two methods on their own. Thus, an integrated sampling approach should be used to fully characterize changes in ant assemblages across ecosystem boundaries, or with vegetation change over time, and particularly so in species-rich habitats such as forest-steppe ecotones.

Seasonal and age-related changes in the stable isotope composition (15N/14N and 13C/12C) of millipedes and collembolans in a temperate forest soil

Seasonal changes in environmental conditions and biotic interactions are often ignored when using stable isotope analysis for reconstructing the trophic structure of soil communities in temperate ecosystems. In this study, we estimated seasonal and age-related changes in δ13C and δ15N values in three epigeic species of collembolans (Pogonognathellus longicornis, Orchesella flavescens and Isotoma viridis) and two litter-dwelling species of millipedes (Polydesmus denticulatus and Leptoiulus proximus) in deciduous and coniferous forest stands in central Russia. Age-related changes in δ13C or δ15N values were either absent or negligible (within 1‰) in L. proximus, but adult and subadult specimens of P. denticulatus were enriched in 15N compared to early larval stages. Since the adults of P. denticulatus were generally more enriched in 15N than adults of L. proximus, they presumably occupy more distinct trophic niches than juveniles do. Age-related changes in isotopic composition were small or absent in collembolans studied. Neither δ13C nor δ15N values of millipedes changed significantly during the vegetation season. In contrast, consistent seasonal changes in δ13C and δ15N values were found in collembolans. Increased δ13C values coincided with the period of minimum soil moisture and correlated with a decreased C/N ratio in collembolan tissues. These changes can largely be attributed to the depletion of lipid-rich storage tissues. Seasonal changes in δ15N values were similar among collembolan species, yet slightly varied between habitats. A general trend of increasing δ15N values from June to September–October may indicate either a reduced importance of non-vascular plants (algae and lichen) in collembolan diet or variation in the isotopic composition of these plants. Overall, our data show that seasonal variations should be taken into account when estimating the isotopic composition of epigeic collembolans in forest soils.

Evaluating the efficacy of land snail survey techniques in Hawaii: implications for conservation throughout the Pacific

Terrestrial micromolluscs (snails with an adult maximum shell dimension <5 mm) constitute a considerable proportion of the land snail fauna of the Pacific. However, micromolluscs are often underestimated in biological surveys because of size bias. It has been argued that visual searches are preferable on Pacific islands because: (1) size biases are limited based on the understanding that most native Pacific island land snails are very small, and (2) amount of labor is less than other methods such as soil surveys and adequate for inventory purposes (though not for abundance assessments). To test whether visual surveys and soil surveys were accurately recording all taxa, land snail inventories were completed in three forest reserves (5 sampling sites in each) on the island of Oahu, Hawaii. Visual surveys involved 30-min visual search in a 10 m2 site; soil surveys involved sieving leaf litter and topsoil from four 0.3 m2 quadrats and extracting snails with the aid of a microscope. The data indicate a size and microhabitat bias associated with both techniques. Visual surveys consistently collected large arboreal and litter-dwelling species but missed a significant portion of micromolluscs, while soil surveys collected micromolluscs but missed larger snails. Because of such biases, employing both methods is critical for collecting all taxa at a survey location. As such, we recommend that future land snail surveys on Pacific Islands incorporate both survey techniques. Obtaining a complete inventory is critical if we are to understand species distributions and patterns of diversity and make well-informed conservation recommendations.

Revision and cladistic analysis of the Guineo-Congolian spider genus Smeringopina Kraus (Araneae, Pholcidae).

The genus Smeringopina Kraus, 1957 is revised, with redescriptions of the nine previously known species and descriptions of 35 new species. Smeringopina is largely restricted to the tropical forests of West and Central Africa. It includes both large species that build their domed sheet-webs in protected spaces near the ground, and small (probably derived) litter-dwelling species. With leg spans up to 18 cm the former group includes some of the largest pholcids known. A first cladistic analysis of Smeringopina, based on 68 morphological (including SEM) characters, suggests several well-defined species groups but also identifies some problematic species whose phylogenetic position needs further study. The ‘Da-homey-Gap’ separates two small western clades (the guineensis species group and two species of the ankasa group) from all other species. The following new species are described: S. ankasa; S. attuleh; S. bamenda; S. bayaka; S. belinga; S. bioko; S. bomfobiri; S. bwiti; S. chaillu; S. djidji; S. ebolowa; S. essotah; S. etome; S. fang; S. fon; S. ibadan; S. iboga; S. kala; S. kikongo; S. kinguele; S. kribi; S. lekoni; S. luki; S. mayebout; S. mbouda; S. mohoba; S. moudouma; S. ndjole; S. ngungu; S. nyasoso; S. ogooue; S. sahoue; S. simintang; S. tchimbele; S. tebe.

An experimental test of facilitation between non-native earthworms

Invasional meltdowns, in which facilitation between species causes an accelerating increase in the number of introduced species or impacts, can cause large impacts in invaded systems. Earthworm invasion of northern forests has been suggested as a meltdown, with litter-dwelling species altering soil structure and facilitating mineral-soil or deep-burrowing earthworms that may be less capable of invading intact forest floors. We examined facilitation and synergistic effects of a litter-dwelling species ( Dendrobaena octaedra Savigny, 1826) and a deep-burrowing species ( Lumbricus terrestris L., 1758). Boreal forest soil cores were inoculated with D. octaedra, L. terrestris, both species, a higher density of L. terrestris, or no worms. After 4.5 months, we found no differences in survival or biomass between treatments for either species. Cocoon production did not differ for L. terrestris, but D. octaedra produced significantly fewer cocoons with L. terrestris. The two species had an additive effect on organic horizon depths and bulk densities. Thus, they did not appear to facilitate each other or have synergistic effects as would be predicted in an invasional meltdown.

Community Structure of Leaf-Litter Ants in a Neotropical Dry Forest: A Biogeographic Approach to Explain Betadiversity

This paper describes habitat and geographic correlates of ant diversity in Serra da Bodoquena, a poorly surveyed region of central-western Brazil. We discuss leaf-litter ant diversity on a regional scale, with emphasis on the contribution of each of the processes that form the evolutionary basis of contemporary beta diversity. The diversity of leaf-litter ants was assessed from a series of 262 Winkler samples conducted in two microbasins within a deciduous forest domain. A total of 170 litter-dwelling ant species in 45 genera and 11 subfamilies was identified. The data showed that the study areas exhibited different arrangements of ant fauna, with a high turnover in species composition between sites, indicating high beta diversity. Our analysis suggests that the biogeographic history of this tropical dry forest in the centre of South America could explain ant assemblage structure more than competitive dominance. The co-occurrence analysis showed that species co-occur less often than expected by chance in only two of the localities, suggesting that, for most of the species, co-occurrences are random. The assessment of the structure of the diversity of litter-dwelling ants is the first step in understanding the beta diversity patterns in this region of great biogeographic importance.

Forest Snail Faunas From S. E. Queensland and N.E. New South Wales (Australia): Patterns Of Local and Regional Richness and Differentiation

While regional snail faunas of low-latitude regions tend to be richer than similar areas at high latitude, there seems to be little difference between site (e.g. < 400 m 2 ) richness, which often ranges between 20 and 40 species across a wide latitudinal range. Given this seeming paradox, it is surprising how little investigation has been made into how land snail species are packed into the tropical landscape across multiple scales. This paper addresses this question by analyzing faunal lists from six regions spread across a 550 km extent in the temperate rain forests of eastern Australia. Considerable heterogeneity was observed both within similar habitat types within (ca. 40−60% faunal similarity) and between (ca. 10−50%) different regions. The Charopidae constituted the largest fraction of the fauna (up to 70% of species), and were thus responsible for most of the variation in composition. While the number of species per region (ca. 30−50) was broadly comparable to Europe and North America, the rate of faunal turnover with distance was found to be 2− 30 times greater. While geographic turnover in European and North American faunas is largely driven by large species, in eastern Australia turnover was largely driven by small, litter-dwelling species that tend to be unique to each region. The comparative richness of the eastern Australian fauna is thus largely related to evolutionary processes that have caused divergence at regional scales, rather than increased niche-packing or syntopic diversity at site scales.

Physical effects of weather events on the abundance and diversity of insects in North American forests

We summarize the effects of major weather events such as ice storms, wind storms, and flooding on the abundance and diversity of terrestrial forest insects and their allies. This synthesis indicates that weather events influence both spatial and temporal patterns of forests and insect communities in North American landscapes. The Atlantic and Pacific oceanic sides of the continent are relatively more susceptible to ice and wind storms, respectively. There have been more studies and reports on the responses of forest insects to wind storms, and on economically important subcortical insects than on gall-forming, foliage-feeding, fungal-feeding, litter-dwelling, pollinating, parasitizing, predaceous, root-feeding, and sap-feeding insects. Weather events positively affect populations of subcortical insect species, and impact their colonization patterns and dynamics. Species belonging to genera such as Dendroctonus (Scolytidae) and Monochamus (Cerambycidae) may sometimes cause economic damage by colonizing residual live tree, and dead trees, rendering the wood unsalvageable. Subsequent outbreaks of spruce beetle, Dendroctonus rufipennis (Kirby) and Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, have been frequently documented in western North American forests following wind events. Wind disturbances have also been observed to accelerate the life-cycles of D. rufipennis and Semanotus litigiosus (Casey) (Cerambycidae), and in rare instances, have caused Monochamus spp. to become primary colonizers. Populations of other important subcortical species have not always increased dramatically following weather events. Foliage- and pollen-feeding insects may experience mortality directly from a weather event or indirectly through habitat alteration. In some cases, forest insects may use storms to migrate to new habitats. Populations of open-habitat and forest specialist litter-dwelling species have increased and decreased, respectively, subsequent to weather events. Forest specialist species generally rebound within a short period of time, suggesting that they are adapted to these periodic weather events. Little is known about the combined effects of post-weather-disturbance management practices such as salvage-logging and prescribed-burning on insects in North American forests.

Contrasting rainforest and savanna ant faunas in monsoonal northern Australia: a rainforest patch in a tropical savanna landscape

Rainforest in the tropical savanna landscapes of monsoonal Australia is of high biogeographic interest because it occurs as numerous small and isolated patches, and supports a fauna that contrasts markedly with that of the surrounding savanna. The overall ant fauna of monsoonal rainforest is known reasonably well, but with just one exception (Holmes Jungle in Darwin) the faunas of individual rainforest patches have been only superficially studied. This paper comprehensively documents an ant fauna of a spring-fed rainforest patch at the Territory Wildlife Park (TWP) near Darwin, contrasts it with that of surrounding savanna, and compares it with the Holmes Jungle fauna. Ants were sampled at 21 locations within the TWP rainforest, using Winkler sacs for litter-dwelling species (160 samples), standard pitfall traps for ground-active species (75 traps), and baited pitfall traps taped to trees for arboreal species (75 traps). In total, 43 species were collected, with 35 recorded in leaf litter, 24 in ground pitfall traps and 12 in arboreal pitfall traps. Species of Paratrechina and Pheidole collectively comprised 75% of all individuals recorded. Species richness was far higher in the surrounding savanna, and the rainforest and savanna faunas had markedly different species and functional group composition. The rainforest fauna at TWP was remarkably similar to that at Holmes Jungle. The rainforest/savanna contrast in ant diversity across northern Australia is the reverse of that occurring in Neotropical savanna landscapes.