Foraging activity of the processional termiteHospitalitermes hospitalis (Termitidae: Nasutitermitinae) in the rain forest of Brunei,north-west Borneo

Summary Four colonies of the column-forming termiteHospitalitermes hospitalis (Haviland) were studied in a primary forest in Brunei Darussalam, north-west Borneo, and their trails mapped. The termites leave their nest in the afternoon to graze throughout the night, mainly on lichens growing high up on the trunk of a canopy tree. Colonies foraged from 46% to 72% of nights, and the mean and maximum trail length was 28.8 m and 65.2 m respectively. Each colony utilized between 14 and 26 trees, with many trees revisited and trails frequently re-used. The mean diameter of the utilized trees was significantly larger than the mean diameter of trees in the population at the study site. Termites often made consecutive foraging visits to the largest trees, particularlyShorea spp. At three colonies per hectare the nest density is lower than expected as more than 90% of potentially suitable trees are not exploited.     

Escape to the high canopy—thermal deficiency causes niche expansion in a forest‐floor ant

The small formicoxenine ant Temnothorax saxonicus was known from about 40 localities in Central Europe nesting in anorganic substrates on floor of xerothermous forests whereas investigations of 198 tree canopies in 19 forest sites of the same region provided no indication for arboreal nesting or foraging. We present the first evidence for canopy‐nesting populations of T. saxonicus on old Quercus trees in 3 sites having maximum calibrated topsoil temperatures of 17.9 ± 0.3 °C which were significantly (P < 0.007) lower than 22.8 ± 2.0 °C measured in 5 sites with ground‐nesting populations. The thermal deficit on forest floor inhibits brood development in ground nests and caused a moving to canopy were maximum calibrated temperatures of the, now wooden, substrates are at least 26.1 °C for the whole canopy and 30.8 °C in more sun‐exposed spots. T. saxonicus competed here successfully with the obligatory canopy ants T. affinis and T. corticalis. The distributional data of this rope‐climbing study support former results that highest nest densities of small arboreal ants occur in temperate climate over the entire canopy mantle of single trees situated in open land or in park‐like environments but occur in the top of the canopy in tree stands with high degree of canopy closure.     

Canopy Ferns in Lowland Dipterocarp Forest Support a Prolific Abundance of Ants,Termites, and Other Invertebrates1

The epiphytic Bird's Nest Fern (Asplenium nidus complex) has a large basket‐shaped rosette that accumulates leaf litter. We investigated the role of these ferns in supporting invertebrate populations in the primary lowland dipterocarp forest of Danum Valley, Sabah, Malaysia. Ferns were divided into three size classes: large (rosette diameter >60 cm), intermediate (30–60 cm), and small (<30 cm). Seven hectares of forest were surveyed: the canopy had a mean density of 30 large ferns/ha and 20 intermediate ferns/ha. Six large and five intermediate ferns were removed from the crowns of Parashorea tomentella (Dipterocarpaceae) at heights between 39 and 52 m. The largest ferns had fresh weights of ca 200 kg. The mean animal abundance in large and intermediate ferns was 41,000 and 8000, respectively. Termites and ants represented at least 90 percent of the abundance in these ferns. Of die 11 ferns, 4 contained a nest of Hospitalitermes rufus (Nasutitermitinae), while another contained a nest of an undescribed species of Hospitalitermes. An additional 56 small ferns were removed from die low canopy (2–6 m above the forest floor), of which only 1 contained a termite nest (Nasutitermes neoparvus). These results suggest that Bird's Nest Ferns contain ca 0.5 million termites/ha and contribute almost one ton (dry mass) of suspended soil and plant material/ha. Five of the trees containing large ferns were fogged immediately before the removal of die ferns. From these samples we were able to estimate the total number of animals in each tree crown. When each estimate was added to die abundance in each fern, the results suggested that a single large fern may contain from 7 to 93 percent of die total number of invertebrates in die crown. Although these results must be treated with caution because of die small sample size, they have important implications for studies of canopy invertebrates.     

Foraging Behavior and Coexistence of Two Sunbird Species in a Kenyan Woodland

We investigated the mechanism of coexistence of the rare Amani Sunbird (Hedydipna pallidigastra) and the widespread Collared Sunbird (H. collaris), within Brachystegia woodland in the Arabuko‐Sokoke Forest, Kenya. We compared how prey abundance and search strategies affect resource exploitation by the two species. We used foraging theory to direct our measures of feeding activities as influenced by sunbird species, tree species and foraging height. We evaluated invertebrate abundance among tree species at different heights within trees. The Collared Sunbird primarily used the understory, and the Amani Sunbird primarily used the upper‐canopy. Overall, the rate of prey attacks per flight of the Amani Sunbird was 2.8 times greater than that of the Collared Sunbird. The Amani Sunbird, however, used increased search and attack rates in the understory compared with the mid‐ and upper‐canopies, but the Collared Sunbird foraged similarly throughout all strata. We hypothesize that the increased foraging rate of the Amani in the understory reflects increased foraging costs due to interference from the Collared Sunbird in that stratum. Furthermore, the Collared Sunbird exploits rich patches by moving frequently from place to place. The Amani Sunbird forages slowly, with reduced travel rates, and with a greater number of prey captures within a patch. Arthropod density did not differ among the vegetative strata, but was higher in Brachystegia spiciformis and Hymenaea verrucosa than in six other tree species. We hypothesize that the Amani Sunbird appears dependent upon continued tall B. spiciformis trees within the canopy of the Arabuko‐Sokoke Forest.     

A two-phase mosaic in a savanna grassland

A two-phase grassland mosaic was described using species association measures and pattern analysis techniques on local frequency data from six transects of contiguous quadrats. One phase consisted of almost mono-specific patches of Setaria incrassata, which was negatively or not associated with ten common species. The other phase was dominated by Themeda triandra which was positively associated with several species. PQV analyses revealed similar, significant, anisotropic scales of contagion of Setaria and Themeda, with phases alternating over 9 m up-slope and 4 m along the contour. Setaria was associated with a tree canopy and deeper soils of higher organic carbon content than Themeda, which was negatively associated with tree canopies. Excavation of Setaria rhizomes indicated mean densities of 20.5 putative genets/m² and 3.6 ramets per genet. Dense clonal growth, seedling recruitment and a competitive exclusion mechanism may contribute to patch maintenance.     

Habitat use by endemic and introduced rodents along a gradient of forest disturbance in Madagascar

We used logistic and Poisson regression models to determine factors of forest and landscape structure that influence the presence and abundance of rodent species in the rain forest of Ranomafana National Park in southeastern Madagascar. Rodents were collected using live-traps along a gradient of human disturbance. All five endemic rodent species (Nesomys rufus, N. audeberti, Eliurus tanala, E. minor and E. webbi) and the introduced rat Rattus rattus were captured in both secondary and primary forests, but the introduced Mus musculus was only trapped in secondary forest. The abundance of R. rattus increased with the level of habitat disturbance, and it was most common in the heavily logged secondary forest. Furthermore, the probability of the presence of R. rattus increased with decreasing distance from forest edge and decreasing canopy cover, while the probability of presence increased with increasing herbaceous cover, altitude and overstory tree height. The species was never observed farther than 500 m away from human habitation or camp-site. N. rufus prefered selectively-logged forest at altitudes above 900 m a.s.l. Its probability of presence increased with increasing canopy cover, herbaceous cover and distance from forest edge, and with decreasing density of fallen logs, overstory tree height and distance from human habitation. N. audeberti prefered heavily-logged areas, while E. tanala was the only species occurring along the entire range of forest disturbance. We suggest that in the Ranomafana National Park the spread of R. rattus is associated with deforestation.     

Frankia and Alnus rubra Canopy Roots: An Assessment of Genetic Diversity, Propagule Availability, and Effects on Soil Nitrogen

The ecological importance of microbial symbioses in terrestrial soils is widely recognized, but their role in soils that accumulate in forest canopies is almost entirely unknown. To address this gap, this study investigated the Frankia–Alnus rubra symbiosis in canopy and forest floor roots at Olympic National Park, WA, USA. Sixteen mature A. rubra trees were surveyed and Frankia genetic diversity in canopy and forest floor nodules was assessed with sequence-based nifH analyses. A seedling bioassay experiment was conducted to determine Frankia propagule availability in canopy and forest floor soils. Total soil nitrogen from both environments was also quantified. Nodules were present in the canopies of nine of the 16 trees sampled. Across the study area, Frankia canopy and forest floor assemblages were similar, with both habitats containing the same two genotypes. The composition of forest floor and canopy genotypes on the same tree was not always identical, however, suggesting that dispersal was not a strictly local phenomenon. Frankia seedling colonization was similar in canopy soils regardless of the presence of nodules as well as in forest floor soils, indicating that dispersal was not likely to be a major limiting factor. The total soil nitrogen of canopy soils was higher than that of forest floor soils, but the presence of Frankia nodules in canopy soils did not significantly alter soil nitrogen levels. Overall, this study indicates that the Frankia–A. rubra symbiosis is similar in canopy and forest floor environments. Because canopy roots are exposed to different environmental conditions within very small spatial areas and because those areas can be easily manipulated (e.g., fertilizer or watering treatments), they present microbial ecologists with a unique arena to examine root–microbe interactions.     

Canopy manipulations of exotic Bitter Willow (Salix elaeagnos) forest for indigenous seedling recruitment: A pilot study

The invasive exotic tree species Bitter Willow (Salix elaeagnos; Salicaceae) has colonised areas of rank exotic grassland and has been found to contain indigenous seed, dispersed by frugivorous birds into the monospecific stands. This small pilot study examined whether indigenous seedlings that have germinated in the understorey of exotic Bitter Willow stands could be stimulated to establish through the creation of small‐scale canopy gaps. In Bitter Willow forest, four single Bitter Willow trees were poisoned to create canopy gaps. Light transmission and seedling regeneration of tree and shrub species were assessed beneath both the four manipulated and three comparable intact Bitter Willow canopies. Over 3 years, seedling height and density increased more beneath opened compared to intact Bitter Willow canopies. These results suggest that Bitter Willow can fill the roles of both a facilitative nurse and a perch tree. Larger‐scale canopy manipulation experiments of both Bitter Willow and other Salix species are needed to determine the full potential of canopy manipulations for forest restoration.     

Biotic and abiotic determinants of the formation of ant mosaics in primary Neotropical rainforests

1. Ants are widespread in tropical rainforests, including in the canopy where territorially dominant arboreal species represent the main part of the arthropod biomass. 2. By mapping the territories of dominant arboreal ant species and using a null model analysis and a pairwise approach this study was able to show the presence of an ant mosaic on the upper canopy of a primary Neotropical rainforest (c. 1 ha sampled; 157 tall trees from 28 families). Although Neotropical rainforest canopies are frequently irregular, with tree crowns at different heights breaking the continuity of the territories of dominant ants, the latter are preserved via underground galleries or trails laid on the ground. 3. The distribution of the trees influences the structure of the ant mosaic, something related to the attractiveness of tree taxa for certain arboreal ant species rather than others. 4. Small‐scale natural disturbances, most likely strong winds in the area studied (presence of canopy gaps), play a role by favouring the presence of two ant species typical of secondary formations: Camponotus femoratus and Crematogaster levior, which live in parabiosis (i.e. share territories and nests but lodge in different cavities) and build conspicuous ant gardens. In addition, pioneer Cecropia myrmecophytic trees were recorded.     

Under adverse conditions,older small tree finch males (Camarhynchus parvulus) produce more offspring than younger males

Females of many bird species prefer mating with older males, presumably because they provide superior parental care and possibly superior genes. A previous study found that female small tree finches (Camarhynchus parvulus) preferred pairing with old males and had a higher breeding success when paired with old males because their nests were more concealed, higher up in the canopy and therefore less likely to be depredated. However, causes for brood loss have changed over the last decade: predation of small tree finch nests has decreased, whereas brood losses due to parasitism by the invasive parasitic fly Philornis downsi have increased. In the present study, we investigated (a) how the change in predation and parasitism by P. downsi influenced the breeding success of small tree finches, (b) whether there were still differences in breeding success between young and old males, (c) whether P. downsi infestation had a differential effect on nests of young and old males and (d) whether young and old males differed in foraging success. During 2012–2016, we found an overall low influence of predation and a high influence of P. downsi, but neither differed between nests of young and old males. Nests of old males had more fledglings than those of young males. However, the difference in breeding success disappeared when P. downsi numbers were experimentally reduced by injecting an insecticide into nests. This indicates that older males were able to compensate for the detrimental effects of parasitism.     

Influence of a non-native invasive tree on primary succession at Mt. Koma, Hokkaido, Japan

The slopes of Mt. Koma in Japan are undergoing primary succession as a result of a 1929 eruption. Understory vegetation below a non-native invasive tree species, Larix kaempferi, a native tree, Betula ermanii, and in the open were compared to determine if the non-native tree species was influencing species composition. Larix canopies are significantly larger than Betula canopies. Vegetation under Larix canopies had significantly greater richness and diversity than vegetation in the open, vegetation under Betula was intermediate but was significantly greater than the open in diversity. Vegetation cover was highest under Betula and significantly lower in the open. Larix canopy size was positively correlated with size and number of Salix reinii shrubs. Betula canopy size was positively correlated with size but not with number of Salix reinii shrubs. Species assemblages in the three sites are slightly different as shown by DCA. Due to the limited species pool on Mt. Koma the greatest possible extent of differences between the three microsites is not large. At this point Larix certainly appears to be accelerating succession for the non-tree species. If Larix persists on the slopes then succession would be permanently deflected towards a Larix forest. This would be a case of succession being deflected towards dominance by the introduced species. This revised version was published online in June 2006 with corrections to the Cover Date.     

Influence of a developing tree canopy on the yield of Pennisetum pedicellatum sown on a mine spoil

Abstract. Shoot and root biomass yield of a sown grass, Pennisetum pedicellatum, were measured at below-canopy, canopy edge and open locations in young monoculture stands of eight tree species planted on a coalmine spoil. Incident light as percentage of full sunlight decreased from open to canopy edge to below-canopy locations. The shoot and root weights of Pennisetum in different tree stands for each of the three locations were significantly different and were significantly related to each other, and to percentage sunlight across all tree species plots and locations. The gradient of incident light was the principal factor governing the gradient of grass biomass under developing canopies of tree plantations on the mine spoil.     

Carbon dioxide concentrations within forest canopies—variation with time, stand structure, and vegetation type

Vertical CO₂ profiles (between 0.02 and 14.0 m) were studied in forest canopies of Pinus contorta, Populus tremuloides, and in a riparian forest with Acer negundo and Acer grandidentatum during two consecutive growing seasons. Profiles, measured continuously during 1- to 13-day periods in four to five stands differing in overstorey canopy area index (CAI < 4.5; including leaves, branches and stems), were well stratified, with highest [CO₂] just above the forest floor. Canopy [CO₂] profiles were influenced by stand structure (CAI, presence of understorey vegetation), and were highly dependent on vegetation type (deciduous and evergreen). A doubling of CAI in Acer spp. and P. tremuloides stands did not show an effect on upper canopy [CO₂], when turbulent mixing was high. However, increasing understorey biomass in Acer spp. stands had a profound effect on lower canopy [CO₂]. In open stands with a vigorous understorey layer, higher soil respiration rates were offset by increased understorey gas exchange, resulting in [CO₂] below those of the convective boundary layer (CBL). Midday depletions up to 20 ppmv below CBL values could be frequently observed in deciduous canopies. In evergreen canopies, [CO₂] stayed generally above the CBL background values, [CO₂] profiles were more uniform, and gradients were smaller than in deciduous stands with similar CAI. Seasonal changes of canopy [CO₂] reflected changes in soil respiration rates as well as plant phenology and gas exchange of both dominant tree and understorey vegetation. Seasonal patterns were less pronounced in evergreen than in deciduous forests.     

Microbat responses to forest decline

Tree declines have been recorded across forests and woodlands on most continents, causing tree mortality over thousands of square kilometres, yet the impact of tree declines upon mammals have only rarely been quantified. Once the dominant tree over the western parts of the Swan Coastal Plain in Western Australia, tuart (Eucalyptus gomphocephala) forest has been reduced to less than a third of its former range through clearing for agriculture and urban development. Additionally, over the last 30 years, the remnant population has been heavily impacted by a decline that has an unknown cause, but is likely related to a root pathogen coupled with abiotic factors (reduced rainfall, increased salinity and elevated temperatures). Tuart decline is evident as marked canopy dieback, replacement with epicormic growth and increasing bare branches, while leaf litter is lost from the tree surrounds. We examined the effect of tuart decline and other vegetation measures upon bat activity using auditory monitoring. Vegetation structure was correlated with Vespertilionidae bat activity. Falsistrellus mackenziei were more likely to forage around healthy canopies (activity positively correlated with tuart crown density and negatively correlated with tuart crown dieback). By contrast, the other three taxa were more often encountered in declining rather than healthy tuart sites. Chalinolobus gouldii was positively associated with tuart crown dieback. Activity of Vespadelus regulus and Nyctophilus spp. (species not distinguishable from their calls) were significantly positively correlated with an open tall canopy (positively with cover of plants >10 m tall and negatively with overall canopy cover density). There were no vegetation measurements that were strong predictors of activity of two Molossidae species (Ozimops kitcheneri and Austronomus australis), which intercept insects above the forest canopy. This study clearly reveals different factors influencing the activity of bat taxa, which are likely related to where they feed and their manoeuvrability around tree canopies.     

Influence of small scale conditions on the diversity of wood decay fungi in a temperate,mixed deciduous forest canopy

Studies on fungal richness and ecology have been largely disregarded since the first intensive efforts to investigate organismal diversity in forest canopies. We used the Leipzig Canopy Crane research facility to sample wood-decaying fungi in a mixed deciduous forest canopy 10-30 m in height. The structural complexity of the canopy was analysed using different methods, including meteorological measurements. With respect to temperature and relative humidity, marked differences existed between forest floor and upper canopy layers that persisted on smaller scales. Of the 118 taxa found in 128 sample units, pyrenomycetes and corticioid fungi outnumbered other macrofungal groups. Fungal communities showed distinct variations both in species richness and composition with respect to substrate (tree species), height in the canopy, stage of decay, and branch diameter. Pyrenomycetes and their anamorphs dominated the mycobiota on thin, exposed twigs at great heights, indicating their ability to overcome extended periods of drought and high levels of solar irradiance. Other taxa of Tremellales (Exidia spp.), Orbiliales (Hyalorbilia inflatula, Orbilia spp.) or Agaricales (Episphaeria fraxinicola, Cyphellopsis anomala, Lachnella spp.) also exhibited features that enabled them to develop in lesser protected habitats within tree crowns.     

The influence of tree canopies and elephants on sub-canopy vegetation in a savannah

The apparent influence of elephants on the structure of savannahs in Africa may be enhanced by management activities, fire and other herbivores. We separated the effect elephants have on grasses, woody seedlings (<0.5 m) and saplings (0.5–2 m) from the effect of tree canopies (canopy effect), and herbivory (park effect). We defined the canopy effect as the differences between plant abundances and diversity indices under tree canopies and 20 m away from these. Our testing of the park effect relied on the differences in the sub-canopy plant indices inside and outside a protected area that supported a range of herbivores. We based our assessment of the elephant effect on sub-canopy vegetation indices associated with elephant induced reductions in tree canopies. The park and canopy effects were more pronounced than the elephant effect. The park effect suppressed the development of woody seedlings into saplings. Conditions associated with tree canopies benefited woody plants, but not the grasses, as their indices were lower under trees. Elephants reducing canopies facilitated grass species tolerant of direct solar radiation. We concluded that management should consider other agents operating in the system when deciding on reducing the impact that elephants may have on vegetation.     

Effects of Prosopis flexuosa on soil properties and the spatial pattern of understorey species in arid Argentina

Abstract. In arid zones dominant woody plants are capable of causing changes in microclimate and soil properties likely to affect species composition, as well as the establishment and spatial distribution of plant species. In North American and European deserts species richness appears to be higher under the canopy of shrubs and trees, in contrast with Chilean deserts where it seems to be lower. Since Prosopis flexuosa (Fabaceae, Mimosoideae) is the most conspicuous tree in the central Monte desert, Argentina, we analysed the effect of this species on the composition and abundance of the shrub and herbaceous layers and on soil properties. We considered two mesohabitats: ‘under P. flexuosa canopy’ and ‘intercanopy areas’. In addition, we analysed the differences between two microhabitats under canopies: ‘northern part of the canopy’ and ‘southern part of the canopy’. Results indicate that species composition and soil properties are affected by both mesohabitats and microhabitats. We found a higher number of shrubs under canopies, whereas that of grasses and perennial forbs increased in intercanopy areas. Concentrations of organic matter, nitrogen, potassium and phosphorus, factors limiting biological productivity in Monte desert soils, were significantly higher under than outside P. flexuosa canopies. Electrical conductivity and concentrations of Na⁺, Ca⁺⁺, Mg⁺⁺ were higher in the northern than in the southern microhabitats. No differences in species richness, evenness or diversity were found between mesohabitats or between microhabitats. We conclude that P. flexuosa modifies the spatial pattern of plant species in the shrub and herbaceous layers and the chemical conditions of the soil, generating spatial heterogeneity on different scales.     

Temporal and spatial patterns of foraging in two syntopic ant species,Manica yessensis and Formica lemani,on Mount Fuji,Japan

Spatiotemporal characteristics of terrestrial foraging were studied in two ant species, Manica yessensis and Formica lemani, in a volcanic desert on the southeast slope of Mount Fuji, Gotenba, Japan. Both ants are common in this habitat, and they construct underground nests in this dry area with sparse vegetation. Nests of M. yessensis have multiple nest-openings on the surface, whereas nests of F. lemani have very few openings, but their nesting and foraging areas overlap completely. A “mark-and-observe” method applied to M. yessensis demonstrated that worker ants of this species move between openings more than 3 m away. A study plot (6 m × 12 m quadrat) was set up, in which all nest-openings of both species were mapped. Day-long observations on numbers of foragers in this plot revealed that foraging M. yessensis are active in morning and evening, while F. lemani continues foraging all day, but both species cease activity at night. Associations between locations of foragers and nest-openings differed significantly between the two species, that is, surface foraging of M. yessensis workers was largely confined to the vicinity of their nest-openings, whereas foragers of F. lemani travelled far from their nest-openings. The function of multiple nest-openings in M. yessensis is discussed.     

Occurrence of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> in Canopies of a Natural Lucidophyllous Forest in Japan

A total of 39 Bacillus thuringiensis isolates were recovered from 38 leaves collected from 5- to 10-m-high canopies of 8 micro-/meso-phanerophyte species in a lucidophyllous forest of Japan. B. thuringiensis-positive leaves accounted for 1.4% of a total of 2805 leaves from 15 tree species. The frequency of the organism was 0.8% among the Bacillus cereus/B. thuringiensis group. Of 39 isolates obtained, 27 (69.2%) were allocated to 11 H serovars, and 12 isolates remained unidentified: 11 were motile but lacked reactivity to the 55 reference antisera, and 1 isolate was not flagellated. Two H serovars, kurstaki (H3abc) and tohokuensis (H17), occurred predominantly on canopy phylloplanes. Larvicidal activities against Bombyx mori and/or Aedes aegypti were associated with 49% of the canopy isolates. Strong hemolysis was induced by parasporal inclusion proteins of the two isolates of serovar israelensis (H14). Hemagglutinating (lectin) activity was associated with parasporal proteins of nine isolates. There was little correlation between insecticidal activity and lectin activity.     

Diel and seasonal patterns of foraging activity in the arboreal ant Crematogaster matsumurai Forel

The foraging habits of the arboreal ant Crematogaster matsumurai Forel were studied in natural and captive colonies in southern Kyushu, Japan. The nests of C. matsumurai are made mainly in the trunks of living trees. In the natural environment, the species mainly lives in decayed parts of relatively tall trees, such as Acer palmatum, Prunus jamasakura and Prunus yedoensis. Observation over a 24 h period showed that C. matsumurai foraged actively at night as well as during the day. The foraging of the workers out of the nest was seen from early spring to late autumn, both on the tree and on the ground. As protein sources, aphids were mainly collected by foragers from the tree, while small parts of dead insects or other arthropods were mainly collected from the ground surface. The foraging activity of workers is assumed to be influenced by the quantity and quality of food rather than seasonality.