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Diagrammatic illustration of how looking at canopy samples with canopy downwards or from the ground upwards perspectives may alter the way the samples are interpreted
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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 ar...
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The construction of shelters on plants by arthropods might influence other organisms via changes in colonization, community richness, species composition, and functionality. Arthropods, including beetles, caterpillars, sawflies, spiders, and wasps often interact with host plants via the construction of shelters, building a variety of structures suc...
Citations
... We classified three forest strata (understory, midstory, and canopy) in relation to the vertical distribution of foliage and density of the surrounding vegetation. We found that vegetation density was clearly distinct among these strata, and we assume that nectarivores rather orient themselves along the vegetation structure than based on absolute height (McCaig et al., 2020). The understory was classified according to the height of the dense surrounding shrub and palm tree layer (0 m until between 3 m and 10 m). ...
Premise:
Vertical stratification is a key feature of tropical forests and plant-frugivore interactions. However, it is unclear whether equally strong patterns of vertical stratification exist for plant-nectarivore interactions and, if so, which factors drive these patterns. Further, nectar-inhabiting bacteria, acting as "hidden players" in plant-nectarivore interactions, might be vertically stratified, either in response to differences among strata in microenvironmental conditions or to the nectarivore community serving as vectors.
Methods:
We observed visitations by a diverse nectarivore community to the liana Marcgravia longifolia in a Peruvian rainforest and characterized diversity and community composition of nectar-inhabiting bacteria. Unlike most other plants, M. longifolia produces inflorescences across forest strata, enabling us to study effects of vertical stratification on plant-nectarivore interactions without confounding effects of plant species and stratum.
Results:
A significantly higher number of visits were by nectarivorous bats and hummingbirds in the midstory than in the understory and canopy, and the visits were strongly correlated to flower availability and nectar quantity and quality. Trochiline hummingbirds foraged across all strata, whereas hermits remained in the lower strata. The Shannon diversity index for nectar-inhabiting bacterial communities was highest in the midstory.
Conclusions:
Our findings suggest that vertical niche differentiation in plant-nectarivore interactions seems to be partly driven by resource abundance, but other factors such as species-specific preferences of hummingbirds, likely caused by competition, play an important role. We conclude that vertical stratification is an important driver of a species' interaction niche highlighting its role for promoting biodiversity and ecosystem functioning.
... Fogging techniques were extensively used in the past to sample tropical forests, revealing compelling evidence of a huge diversity of insects, such as beetles and treehoppers in the canopies (see Erwin, 1989 for a review). However, further evidence have shown that different arthropods groups have particular responses to stratification (Whitworth et al., 2016;McCaig et al., 2020;Amorim et al., 2022;Oliveira-Santos et al., 2022). The trap-nesting bees abundance and richness, for instance, can be evenly distributed between understory and canopy (Stangler et al., 2016). ...
Tropical forests are three-dimensional with the presence of numerous micro-environments formed by horizontal and vertical gradients. Such micro-environments can affect the nesting preference of organisms, including the trap-nesting Hymenoptera. Bees and wasps are key elements in ecosystems and are considered as sensitive to environmental changes, and trap-nests sampling methodology is widely used in their ecological and conservation studies. However, many uncertainties remain about nesting site preferences. From this perspective, our aim is to assess the diversity descriptors of trap-nesting Hymenoptera in different micro-environments. The sampling was conducted on three micro-environments (canopy, understory and treefall gaps) replicated on ten permanent plots within a Brazilian Atlantic forest hotspot. In each micro-environment, we installed trap-nest stations made by a set of twenty bamboo artificial nests. We found 762 brood cells from ten wasp and five bee species. The rarefaction curves indicate the lower species richness in understory stations, while treefall gaps and canopy stations were not significantly different. We analyzed abundance, mortality and parasitism rates using generalized linear models, but only abundance varies significantly among micro-environments. Our data indicates that trap-nesting Hymenoptera prefer to nest in micro-environments with higher exposure of sunlight. Canopy and treefall gap assemblages are consistently more abundant and diverse than understory probably due the higher temperature and lower humidity. On the other hand, mortality, parasitism rates, and the species composition were similar among environments. Our hypothesis is that the species composition was not affected as these species have a foraging range that encompasses nearby micro-environments.
Keywords:
Abundance; Diversity; Sunlight exposure; Tropical forest
... The increase in vegetation cover by plants fertilized with sewage sludge is important for the recovery process affecting different trophic levels, including herbivores and predators in the herbaceous layer with a more favourable microclimate and oristic composition [23] such as greater weed diversity [48]. The better plant growth with sewage sludge increases food quality and quantity besides more hiding and reproduction places for the predators [49]. Herbivorous insects are attracted to the tree canopies, searching for food, and thus their enemies follow them [49]. ...
... The better plant growth with sewage sludge increases food quality and quantity besides more hiding and reproduction places for the predators [49]. Herbivorous insects are attracted to the tree canopies, searching for food, and thus their enemies follow them [49]. Insect colonization indicates that the recovery process is being effective to re-establish the ecosystem dynamics [28] with denser vegetation reducing the antagonistic effect between predators on herbivores [23]. ...
... The competition between spiders and ground beetles (Carabidae) affected the arthropod diversity [55]. Tree canopies with fruits, owers, and leaves attracted herbivorous insects (e.g., coleopterans, formicids, homopterans, and termites) in the Australian tropical rainforest [49]. The orthopterans success was attribute to their generalist diet feeding on crops, grasses, and weeds [56] and a more developed canopy protect them from excessive sunlight and to predators such as birds, coleopterans, dipterans, and heteropterans [49]. ...
Plant species, monitoring measures, and alternative fertilization with sewage sludge accelerate recovering of degraded areas. The objective of this study was to evaluate the numbers of leaves/branch and branches/plant of Sapindus saponaria L., the ground cover by this plant and the ecological indexes of abundance, diversity, and species richness of insects and spiders, and of their interactions, during 24 months on trees grown in a degraded area with or without dehydrated sewage sludge as fertilizer. The metrics of plant, soil cover, and arthropods were higher on the S. saponaria plants fertilized with dehydrated sewage sludge. The abundance of chewing insects, tending ants, and spiders was greater on larger S. saponaria tree crown. The abundance of these last groups of organisms associated, negatively, with that of Coleoptera, but those of ants reduced that of the predators. The ecological indexes of arthropods on S. saponaria plants shows the suitability of this plant for recovering programs of degraded areas and the use of dehydrated sewage sludge as fertilizer increased these indices and the possibility of using insects and spiders on the crown of this plant as bioindicators.
... Some authors argue that most of the arthropods are terrestrial insects, and therefore soil dwellers for at least part of their life cycle, accounting for the highest diversity (Giller 1996), although it is believed that the canopy holds the key to the enormous arthropod diversity (Erwin 1988;Stork et al. 1997;Basset 2001). The vertical stratification of insects in the tropical forests, along with their seasonal fluctuations, shapes the structure of their communities, since their abundance and feeding habits conform to the functional relationships of those ecosystems (Sutton et al. 1983;Basset et al. 2003;Sobek et al. 2009;McCaig et al. 2020). Microclimatic gradients occur in different biotopes, such as between understory and canopy, impacting both the abundance and biomass, and therefore the seasonality of insect populations (Wolda 1978a, b;Lowman 1982;Fowler et al. 1993). ...
... Canopy strata do influence not only the plant populations encountered there, but also the diversity of insect taxa and their life-history strategies. For instance, many herbivores and insect-related (e.g., parasitoids and predators) primarily occur in the canopy, where host plants grow and blossom because these are their food sources (McCaig et al. 2020). Therefore, our study focused on the assessment of temporal shifts in the understory dipteran community, which must be kept in mind for further comparisons involving multiple strata. ...
Insect life cycles are short-term and therefore sensitive to immediate changes triggered by climate, vegetation structure, or land use management; hence, the insect populations shape the communities and functional relationships in tropical forests. In this study, we hypothesized that seasonal variations of the dipteran families respond in different ways to changes of weather conditions, thereby affecting their population dynamics. In a one-hectare plot, we surveyed the fly community inhabiting the understory of a Neotropical rainforest. Over a yearly cycle, we used three Malaise traps operated continuously for 365 days and recorded a total of 68,465 fly specimens belonging to 48 families of Diptera, 15 of which were most abundant, accounting for 99.2% of all sampled individuals. The results of the trapping frequency indices (TFIs) exhibited significant population fluctuations in 12 of the 15 most abundant families, which were particularly correlated with temperature or precipitation. Based on such variations, we identified four seasonal patterns as follows: (i) Spring-Autumn bimodal pattern (Cecidomyiidae, Sciaridae, Phoridae, Stratiomyidae); (ii) Spring pattern (Mycetophilidae, Dolichopodidae, Ceratopogonidae); (iii) Autumn pattern (Chironomidae, Psychodidae); (iv) Winter pattern (Empididae, Tipulidae, Ditomyiidae). From a functional perspective, we found the prevalence of families with saprophagous larvae, in addition to phytophagous, fungivores, and predacious. Our results suggest a key role played by the Diptera community on structuring the functional clusters, both in terms of taxonomic composition and on seasonal shifts of abundance, thus influencing the dynamic processes of nutrient cycling in the understory.
... Over the last four decades, studies have uncovered unexpected additional complexity in these forests with the canopy (the leafy crowns of trees) as a vertically stratified ecosystem interconnected with other strata of the forests 1 . Different aspects of canopy ecology and diversity have been studied to date, including climatic gradients within the forest 2 , biomass 3,4 , abundance 5 , alpha diversity 6 , beta diversity 7 , species interactions 8 , biogeochemical cycles 9 , guild structure 10 , long-term succession 11 , community organization 12 , models of vertical distribution 13 , human impact 14 , and other parameters, with a growing number of papers on techniques and methods [15][16][17][18][19][20][21][22][23][24][25][26][27][28] . For example, a study on the island of Borneo 5 demonstrated that 85% of the variability in arthropod abundance is explained by variability in total leaf area-hence, understory vegetation and canopy contributed disproportionately to the total abundance. ...
Tropical forests are among the most biodiverse biomes on the planet. Nevertheless, quantifying the abundance and species richness within megadiverse groups is a significant challenge. We designed a study to address this challenge by documenting the variability of the insect fauna across a vertical canopy gradient in a Central Amazonian tropical forest. Insects were sampled over two weeks using 6-m Gressitt-style Malaise traps set at five heights (0 m–32 m–8 m intervals) on a metal tower in a tropical forest north of Manaus, Brazil. The traps contained 37,778 specimens of 18 orders of insects. Using simulation approaches and nonparametric analyses, we interpreted the abundance and richness of insects along this gradient. Diptera, Hymenoptera, and Coleoptera had their greatest abundance at the ground level, whereas Lepidoptera and Hemiptera were more abundant in the upper levels of the canopy. We identified species of 38 of the 56 families of Diptera, finding that 527 out of 856 species (61.6%) were not sampled at the ground level. Mycetophilidae, Tipulidae, and Phoridae were significantly more diverse and/or abundant at the ground level, while Tachinidae, Dolichopodidae, and Lauxaniidae were more diverse or abundant at upper levels. Our study suggests the need for a careful discussion of strategies of tropical forest conservation based on a much more complete understanding of the three-dimensional distribution of its insect diversity.
... These samples can provide a valuable source of feedback to forest growers and researchers to further optimize and inform the management of our forest resources, but obtaining these samples remains a challenge. Canopy samples are typically collected with considerable effort through the use of canopy cranes [21][22][23], arborists, shotguns, crossbows [24,25], line launchers and pole pruners [26]. These techniques can be time-consuming, expensive and in some cases dangerous. ...
Unoccupied Aircraft Systems (UAS) are beginning to replace conventional forest plot mensuration through their use as low-cost and powerful remote sensing tools for monitoring growth, estimating biomass, evaluating carbon stocks and detecting weeds; however, physical samples remain mostly collected through time-consuming, expensive and potentially dangerous conventional techniques. Such conventional techniques include the use of arborists to climb the trees to retrieve samples, shooting branches with firearms from the ground, canopy cranes or the use of pole-mounted saws to access lower branches. UAS hold much potential to improve the safety, efficiency, and reduce the cost of acquiring canopy samples. In this work, we describe and demonstrate four iterations of 3D printed canopy sampling UAS. This work includes detailed explanations of designs and how each iteration informed the design decisions in the subsequent iteration. The fourth iteration of the aircraft was tested for the collection of 30 canopy samples from three tree species: eucalyptus pulchella, eucalyptus globulus and acacia dealbata trees. The collection times ranged from 1 min and 23 s, up to 3 min and 41 s for more distant and challenging to capture samples. A vision for the next iteration of this design is also provided. Future work may explore the integration of advanced remote sensing techniques with UAS-based canopy sampling to progress towards a fully-automated and holistic forest information capture system.
... The integrative IBISCA (Investigating the Biodiversity of Soil and Canopy Arthropods) approach is a good example of the combination of these methods with a wide variety of canopy access tools (e.g., cranes, balloons, rafts, climbers) leading to the development of new sampling protocols (Leponce et al., 2012(Leponce et al., , 2021. Recent large-scale, multi-taxa projects to access the tree canopy have relied on tree felling, canopy cranes, cherry pickers (Nakamura et al., 2017;Volf et al., 2019;McCaig et al., 2020;Mottl et al., 2020), or ground-level fogging using insecticide (Swart et al., 2020). Canopy-dwelling vertebrates including birds, frogs, lizards, and mammals are commonly studied observationally either using binoculars, climbing into the canopy, or using remotely sensed images to identify nests (Milne et al., 2021). ...
The arboreal ecosystem is vitally important to global and local biogeochemical processes, the maintenance of biodiversity in natural systems, and human health in urban environments. The ability to collect samples, observations, and data to conduct meaningful scientific research is similarly vital. The primary methods and modes of access remain limited and difficult. In an online survey, canopy researchers (n = 219) reported a range of challenges in obtaining adequate samples, including ∼10% who found it impossible to procure what they needed. Currently, these samples are collected using a combination of four primary methods: (1) sampling from the ground; (2) tree climbing; (3) constructing fixed infrastructure; and (4) using mobile aerial platforms, primarily rotorcraft drones. An important distinction between instantaneous and continuous sampling was identified, allowing more targeted engineering and development strategies. The combination of methods for sampling the arboreal ecosystem provides a range of possibilities and opportunities, particularly in the context of the rapid development of robotics and other engineering advances. In this study, we aim to identify the strategies that would provide the benefits to a broad range of scientists, arborists, and professional climbers and facilitate basic discovery and applied management. Priorities for advancing these efforts are (1) to expand participation, both geographically and professionally; (2) to define 2–3 common needs across the community; (3) to form and motivate focal teams of biologists, tree professionals, and engineers in the development of solutions to these needs; and (4) to establish multidisciplinary communication platforms to share information about innovations and opportunities for studying arboreal ecosystems.
... The integrative IBISCA (Investigating the Biodiversity of Soil and Canopy Arthropods) approach is a good example of the combination of these methods with a wide variety of canopy access tools (e.g., cranes, balloons, rafts, climbers) leading to the development of new sampling protocols (Leponce et al., 2012(Leponce et al., , 2021. Recent large-scale, multi-taxa projects to access the tree canopy have relied on tree felling, canopy cranes, cherry pickers (Nakamura et al., 2017;Volf et al., 2019;McCaig et al., 2020;Mottl et al., 2020), or ground-level fogging using insecticide (Swart et al., 2020). Canopy-dwelling vertebrates including birds, frogs, lizards, and mammals are commonly studied observationally either using binoculars, climbing into the canopy, or using remotely sensed images to identify nests (Milne et al., 2021). ...
The arboreal ecosystem is vitally important to global and local biogeochemical processes, the maintenance of biodiversity in natural systems, and human health in urban environments. The ability to collect samples, observations, and data to conduct meaningful scientific research is similarly vital. The primary methods and modes of access remain limited and difficult. In an online survey, canopy researchers (n = 219) reported a range of challenges in obtaining adequate samples, including ∼10% who found it impossible to procure what they needed. Currently, these samples are collected using a combination of four primary methods: (1) sampling from the ground; (2) tree climbing; (3) constructing fixed infrastructure; and (4) using mobile aerial platforms, primarily rotorcraft drones. An important distinction between instantaneous and continuous sampling was identified, allowing more targeted engineering and development strategies. The combination of methods for sampling the arboreal ecosystem provides a range of possibilities and opportunities, particularly in the context of the rapid development of robotics and other engineering advances. In this study, we aim to identify the strategies that would provide the benefits to a broad range of scientists, arborists, and professional climbers and facilitate basic discovery and applied management. Priorities for advancing these efforts are (1) to expand participation, both geographically and professionally; (2) to define 2–3 common needs across the community; (3) to form and motivate focal teams of biologists, tree professionals, and engineers in the development of solutions to these needs; and (4) to establish multidisciplinary communication platforms to share information about innovations and opportunities for studying arboreal ecosystems.
... Bait traps are an effective tool for the study of the insect fauna of the upper tiers of forests. Forest crowns are usually studied to a lesser extent than the soil and herbal layer [73,74]. Forest canopies did not attract researchers for a long time due to the logistical difficulties of reaching the tree crowns and the subsequent sampling problems. ...
The possibilities of applying various methods to study Coleoptera give unexpected and original results. The studies were carried out with the help of fermental crown traps in 2018-2020 on the territory of eight regions in the central part of European Russia. The biodiversity of the Coleoptera that fall into crown traps includes 294 species from 45 families. The number of species attracted to the fermenting bait is about a third of the total number of species in the traps (this is 97.4% of the number of all of the caught specimens). The largest number of species that have been found in the traps belong to the families Cerambycidae, Elateridae and Curculionidae. The most actively attracted species mainly belong to the families Cerambycidae, Nitidulidae and Scarabaeidae. The species of these families are equally attracted by baits made of beer, white and red wines. In order to identify the Coleoptera biodiversity of a particular biotope, two-year studies are sufficient, and they should be carried out throughout the vegetation season. Especially good results can be obtained from studies of rare species that are actively attracted by such baits. It is possible to study the vertical-horizontal distribution of Coleoptera fauna in individual biotopes.
... Bait traps are an effective tool for the study of the insect fauna of the upper tiers of forests. Forest crowns are usually studied to a lesser extent than the soil and herbal layer [73,74]. Forest canopies did not attract researchers for a long time due to the logistical difficulties of reaching the tree crowns and the subsequent sampling problems. ...
The possibilities of applying various methods to study Coleoptera give unexpected and original results. The studies were carried out with the help of fermental crown traps in 2018-2020 on the territory of eight regions in the central part of European Russia. The biodiversity of Coleoptera that fall into crown traps includes 294 species from 45 families. The number of species attracted to the fermenting bait is about a third of the total number of species in the traps (this is 97.4% of the number of all caught specimens). The largest number of species that have been found in traps belong to the families Cerambycidae, Elateridae and Curculionidae. The most actively attracted species mainly belong to the families Cerambycidae, Nitidulidae and Scarabaeidae. Species of these families are equally attracted by baits made of beer, white and red wines. To identify the Coleoptera biodiversity of a particular biotope, two-year studies are sufficient, which should be carried out throughout the vegetation season. Especially good results can be obtained from studies of rare species that are actively attracted by such baits. It is possible to study the verti-cal-horizontal distribution of Coleoptera fauna in individual biotopes.
