Flora and Vegetation of Clipperton (La Passion) Atoll, North-Eastern Pacific Ocean: Three Centuries of Changes and Recent Plant Dynamics

Clipperton Atoll (Île de La Passion) is the only atoll in the Tropical Eastern Pacific (TEP) ecoregion and, owing to its isolation, possesses several endemic species and is likely an important stepping stone between Oceania, the remainder of the TEP, including other oceanic islands and the west coast of Central America. We describe the biodiversity at this remote atoll from shallow water to depths greater than one thousand meters using a mixture of technologies (SCUBA, stereo baited remote underwater video stations, manned submersible, and deep-sea drop cameras). Seventy-four unique taxa of invertebrates were identified during our expedition. The majority (70%) of these taxa were confined to the top 400 m and consisted mostly of sessile organisms. Decapod crustaceans and black corals (Antipatharia) had the broadest depth ranges, 100–1,497 m and 58–967 m, respectively. Decapods were correlated with the deepest depths, while hard corals were correlated with the shallow depths. There were 96 different fish taxa from 41 families and 15 orders, of which 70% were restricted to depths <200 m. While there was a decreasing trend in richness for both fish and invertebrate taxa with depth, these declines were not linear across the depth gradient. Instead, peaks in richness at ∼200 m and ∼750 m coincided with high turnover due to the appearance of new taxa and disappearance of other taxa within the community and is likely associated with the strong oxygen minimum zone that occurs within the region. The overall depth effect was stronger for fishes compared with invertebrates, which may reflect ecological preferences or differences in taxonomic resolution among groups. The creation of a no-take marine reserve 12 nautical miles around the atoll in 2016 will help conserve this unique and relatively intact ecosystem, which possesses high predator abundance.

Understanding and predicting the composition and spatial structure of communities is a central challenge in ecology. An important structural property of animal communities is the distribution of individual home ranges. Home range formation is controlled by resource heterogeneity, the physiology and behaviour of individual animals, and their intra‐ and interspecific interactions. However, a quantitative mechanistic understanding of how home range formation influences community composition is still lacking. To explore the link between home range formation and community composition in heterogeneous landscapes we combine allometric relationships for physiological properties with an algorithm that selects optimal home ranges given locomotion costs, resource depletion and competition in a spatially‐explicit individual‐based modelling framework. From a spatial distribution of resources and an input distribution of animal body mass, our model predicts the size and location of individual home ranges as well as the individual size distribution (ISD) in an animal community. For a broad range of body mass input distributions, including empirical body mass distributions of North American and Australian mammals, our model predictions agree with independent data on the body mass scaling of home range size and individual abundance in terrestrial mammals. Model predictions are also robust against variation in habitat productivity and landscape heterogeneity. The combination of allometric relationships for locomotion costs and resource needs with resource competition in an optimal foraging framework enables us to scale from individual properties to the structure of animal communities in heterogeneous landscapes. The proposed spatially‐explicit modelling concept not only allows for detailed investigation of landscape effects on animal communities, but also provides novel insights into the mechanisms by which resource competition in space shapes animal communities.

Abstract. The current research aims at showing as applications working on personal mobile communication terminals such as smartphones, can be useful for exploration of places and, at the same time, as tools able to develop interaction between cultural heritage and users. In this sense, the use of smartphone applications can be combined with GIS in order to make a platform of knowledge useful to support research studies in the field of cultural heritage, with specific reference to accessibility issues and to the combined use of integrated technologies like GPS, QR code and GIS, with the final aim to find an useful methodology for collecting data by visitors and visualizing them through mapping techniques. The research shows how the integration of different systems and technologies can be used as method for inquiring the interactions between users and cultural heritage in terms of accessibility to places. GPS devices can be used to record visitors movements (cultural routes) in terms of space and time; QR code can be used for users interaction with cultural heritage (tourists opinion, heritage ranking, facilities, accessibility); GIS software can be used for data management, analysis and mapping (tourist flows, more visited places). The focus of research is about a combination of information related to cultural routes with the information related to single cultural places. The focus of research is about a combination of information related to cultural routes with the information related to single cultural places. The current research shows the potential use of smartphone applications, as mobile device for collecting data, as means to record rides and more visited places by tourists. The research could be divided into three steps; the first one concerns with GPS that can be used to record routes; the second one deals with interaction between tourists and cultural heritage through a system based on QR code; the third one is about GIS, used as tool for management, analysis and visualization of data flows. In the current research, the field of investigation refers both to the territorial scale of Turin – Milan axis, and to the local scale of small cities localized in the territories in between. The research has been applied to Turin – Milan infrastructural axis, with the aim to represent the relationships that can be established between mobility infrastructure and cultural heritage. Such relationships should be intended in terms of accessibility from mobility infrastructure (motorway exit, service areas, railways stations) to cultural heritage localized in the surrounding landscape. The richness of cultural heritage and landscape along the chosen infrastructural bundle represent a great opportunity for territorial development in terms of attractiveness, both for local inhabitants and for tourists. Nowadays, the use of tracking technologies can be applied to investigate tourist flows, behaviors of local inhabitants in the historic city centre, number of visitors in the city and so on. In this sense it is possible to apply these technologies, which are particularly relevant in urban studies, extending them to the territorial scale of the Turin – Milan region. The large amount of available geo-referenced data can be used in different ways and it is very potential for different kind of analysis: it is possible to show tourist flows in the territory, receive information about more visited places, obtain interaction from users and cultural heritage in terms of visitors opinion about the places, give information to tourists about cultural places, monitor the accessibility to the places, understand the use of means of transport and keep under control the impacts of tourism (social, cultural, environmental) on territory. Applications based on smartphones can be considered a powerful device for visitors but also for institutions that are involved in tourism and cultural heritage management. In fact, the use of mobile applications it can produce a real time data exchange between geographical position of users and system that receives data. The research shows the opportunity to use GPS and QR code, integrated in a single smartphone application, with GIS software. In the current step of the research only the interaction with GPS and GIS has been tested on the case study of Turin – Milan. Further development of research could be realized to test the real integration of QR code with other systems, developing an application that supports QR code and GPS, and installing a barcode or other interactive devices such as NFC (Near Field Communication) on each relevant cultural places. It is evident that different actors, such as tourists, cultural heritage institutions and employers, have to be involved in this process, in order to have a deeper understanding of the problem, also integrating bottom up and top down contributions.

Species assemblages can result from deterministic processes, such as niche differentiation and interspecific interactions, and from stochastic processes, such as random colonisation and extinction events. Although changes in animal communities following disturbances have been widely examined, few studies have investigated the mechanisms structuring communities during ecological succession. We assessed the impact of logging on small mammal and beetle assemblages in landscapes dominated by old-growth boreal forests. Our objectives were to 1) characterize variations in communities during the first 66 years of post-harvest forest succession, 2) determine if there are non-random patterns of species co-occurrence (i.e., deterministic processes), and if there are, 3) establish whether non-random co-occurrences are best explained by habitat attributes or by interspecific interactions. We captured small mammals and beetles along a gradient of forest succession (5–66 years) and in old-growth forest, and characterized key vegetation attributes. First, we tested whether community compositions in clear-cut stands became similar to those in natural stands after 66 years. We then used null models, which were either unconstrained or constrained by habitat attributes, to address the last two objectives and distinguish effects of vegetation attributes from interspecific interactions on community assembly. We showed that beetle assemblages differed in stands 21–30 years post-harvest compared to old-growth forests. In contrast, harvesting did not influence the composition of small mammal communities. Overall, our results suggest that community assembly during forest succession is driven by both stochastic and deterministic processes, the latter being linked to interspecific interactions more strongly than to vegetation attributes.

LOADSS: A GIS-based decision support system for regional environmental planning

A part of the Square Kilometre Array (SKA) will be constructed in the northern Karoo of South Africa on approximately 135 000 ha of land. This land is formerly privately owned rangelands (farms) that were purchased by the South African National Research Foundation (NRF), on which the South African Radio Astronomy Observatory, as part of the global SKA project, will erect the SKA infrastructure. Additionally, a long-term environmental research programme will be established to investigate various dryland ecosystem components at a landscape scale. Livestock has been removed from the farms, and the area is now managed by the South African National Parks (SANParks) as the Meerkat National Park. The land-use and land cover changes present an unprecedented opportunity to study ecosystem dynamics. The property will be established as an NRF science park, incorporating an SKA research platform for radio astronomy and an environmental research platform of the South African Environmental Observation Network, with additional environmental research conducted by SANParks and their collaborators. We briefly describe current knowledge of the area’s environment, and report on past and contemporary changes in this part of the Karoo. We present a conceptual model for the larger landscape which considers possible future land-use scenarios, the projected trajectories of change under these scenarios, and factors influencing these trajectories. These deliberations represent the foundation for future research in this landscape and the development of an environmental observation research platform in the Karoo at SKA.Significance: We summarise an extensive environmental baseline report on the SKA property and surrounding areas. Withdrawal of livestock and other changes – such as clearing of alien invasive plants, reduced predator control and reduction in water-point maintenance – are expected to bring about changes in ecological processes and plant and animal communities. We present a conceptual model of scenarios to test possible future trajectories as a first step towards an earth system science research platform in the NRF science park.

Curating protected area-level species lists in an era of diverse and dynamic data sources

Little is known about how positive biotic interactions structure animal communities. Nest association is a common reproductive facilitation in which associate species spawn in nests constructed by host species. Nest-associative behaviour is nearly obligate for some species, but facultative for others; this can complicate interaction network topology. Nest web diagrams can be used to depict interactions in nesting-structured communities and generate predictions about those interactions, but have thus far only been applied to cavity-nesting vertebrate communities. Likewise, the stress-gradient hypothesis (SGH) predicts that prevalent biotic interactions shift from competition to facilitation as abiotic and biotic stress increase; this model has been hardly applied to animal communities. Here, both of these models were applied to nest-associative fish communities and extended in novel ways to broaden their applicability. A nest web was constructed using spawning observations over 3 years in several streams in south-western Virginia, USA. Structural equation modelling (SEM) was then implemented through an information-theoretic framework to identify the most plausible nest web topology in stream fish communities at 45 sites in the New River basin of the central Appalachian Mountains, USA. To test the SGH, the per-nest reproductive success of 'strong' (nearly obligate) nest associates was used to represent interaction importance. Eigenvectors were extracted from a principal coordinate analysis (PCoA) of proportional species abundances to represent community structure. Both of these metrics were regressed on physical stress, a combination of catchment-scale agricultural land use and stream size (representing spatiotemporal habitat variability). Seventy-one per cent of SEM model evidence supported a parsimonious interaction topology in which strong associates rely on a single host (Nocomis), but not other species. PCoA identified a gradient of community structure dominated by Nocomis and associates, to communities dominated by other reproductive groups. Both metrics of interaction importance responded positively to physical stress. This study demonstrates that nest webs can be useful in a variety of systems and that SEM can be a quantitative extension of this framework. Likewise, the SGH can be used to understand positive interactions in animal communities and can be extended to predict proportional representation of facilitating and beneficiary species in communities.

The role of positive interactions in structuring plant and animal communities is increasingly recognized, but the generality of current theoretical models has remained practically unexplored in animal communities. The stress gradient hypothesis predicts a linear increase in the intensity of facilitation as environmental conditions become increasingly stressful, whereas other theoretical models predict a maximum at intermediate environmental stress. We tested how competition and facilitation between herbivores change over a manipulated gradient of nutrient availability. We studied the effect of grazing by pond snails (Lymnaea stagnalis L.) as bulk grazers on aquatic caterpillars (Acentria ephemerella Denis and Schiffermüller) as small specialist grazers along an experimental gradient of environmental nutrient concentration. Higher nutrient levels increased overall total plant biomass but induced a shift toward dominance of filamentous algae at the expense of macrophytes. Facilitation of caterpillars by snail presence peaked at intermediate nutrient levels. Both caterpillar biomass and caterpillar grazing on macrophytes were highest at intermediate nutrient levels. Snails facilitated caterpillars possibly by removing filamentous algae and increasing access to the macrophyte resource, whereas they did not affect macrophyte biomass or C: nutrient ratios, a measure of food quality. We conclude that competition and facilitation in herbivore communities change along nutrient availability gradients that affect plant biomass and community composition. Understanding how interspecific interactions may change in strength and direction along environmental gradients is important to predict how the diversity and structure of communities may respond to the introduction or removal of herbivore species in ecosystems.

The effects of anthropogenic climate change on biodiversity are well known for some high‐profile Australian marine systems, including coral bleaching and kelp forest devastation. Less well‐published are the impacts of climate change being observed in terrestrial ecosystems, although ecological models have predicted substantial changes are likely. Detecting and attributing terrestrial changes to anthropogenic factors is difficult due to the ecological importance of extreme conditions, the noisy nature of short‐term data collected with limited resources, and complexities introduced by biotic interactions. Here, we provide a suite of case studies that have considered possible impacts of anthropogenic climate change on Australian terrestrial systems. Our intention is to provide a diverse collection of stories illustrating how Australian flora and fauna are likely responding to direct and indirect effects of anthropogenic climate change. We aim to raise awareness rather than be comprehensive. We include case studies covering canopy dieback in forests, compositional shifts in vegetation, positive feedbacks between climate, vegetation and disturbance regimes, local extinctions in plants, size changes in birds, phenological shifts in reproduction and shifting biotic interactions that threaten communities and endangered species. Some of these changes are direct and clear cut, others are indirect and less clearly connected to climate change; however, all are important in providing insights into the future state of terrestrial ecosystems. We also highlight some of the management issues relevant to conserving terrestrial communities and ecosystems in the face of anthropogenic climate change.

The burrow microhabitats created by burrowing mammals, as a hotspot for biodiversity distribution in ecosystems, provide multiple critical resources for many other sympatric species. However, the cascading effects of burrow resources on sympatric animal community assemblages and interspecific interactions are largely unknown. During 2020-2023, we monitored 184 Chinese pangolin (Manis pentadactyla) burrows using camera traps to reveal the burrow utilization patterns of commensal species. We totally recorded up to 57 species, with 19 mammal species, 32 bird species, and 1 reptile species recorded in the burrows revisited by Chinese pangolin, with 19 mammal species and 25 bird species in the non-revisited burrows. Among them, most bird species as peripheral species primarily utilize soil mounds while most mammal species as burrow-used species utilize burrow tunnels. The structure of animal communities in the burrows revisited by Chinese pangolins is more complex than that in the burrows not revisited. Furthermore, the positive correlation between community species in pangolin-revisited burrows is also stronger. Our results demonstrate that the presence and repeated visitation by Chinese pangolins could enhance positive interactions (i.e., the emergence of one species promotes the emergence of another) among species that utilize the burrow resources (particularly, burrow-used species). Our study provides the first evidence that the ecological role of the Chinese pangolin and its associated burrow microhabitats in promoting the coexistence of burrowing commensals and the restoration of Chinese pangolin populations may potentially contribute to the restoration of local biodiversity and ecological processes.

Foundation species provide critical resources to ecological community members and are key determinants of biodiversity. The barnacle Balanus glandula is one such species and dominates space among the higher reaches of wave-swept shores (Northeastern Pacific Ocean). This animal produces a cuticular glycoprotein (named "MULTIFUNCin") of 199.6kDa, and following secretion, a 390kDa homodimer in native form. From field and lab experiments, we found that MULTIFUNCin significantly induces habitat selection by conspecific larvae, while simultaneously acting as a potent feeding stimulant to a major barnacle predator (whelk, Acanthinucella spirata). Promoting immigration via settlement on the one hand, and death via predation on the other, MULTIFUNCin drives opposing demographic processes toward structuring predator and prey populations. As shown here, a single compound is not restricted to a lone species interaction or sole ecological function. Complex biotic interactions therefore can be shaped by simple chemosensory systems and depend on the multifunctional properties of select bioactive proteins.

Community level ecological traits are thought to affect invasibility as more diverse communities with complex trophic interactions may be associated with greater biotic resistance. Elucidation of the nature of this relationship is often hampered by difficulties in characterising food webs, particularly where field data are lacking. We attempted to overcome this by coupling food web modelling with information-theoretic analysis of the modelled webs. In addition, we also investigated the possibility that species level trends in trophic traits of established aliens might reflect exploitation of empty niches. We constructed hypothetical food webs of 26 natural and artificial lentic habitats from a data set consisting of 370 fish species representing 71 families. Using these food webs, we investigated associations at the community level between food web traits and network topology and number of alien fish species using an information-theoretic approach based on a set of competing a priori hypotheses. At the species level, we similarly tested for trends in trophic traits of established alien fishes using the information-theoretic approach in addition to nMDS of diet data. We found that native species richness in a community was the most important determinant of the number of alien fish taxa, displaying an inverse relationship. Our data also show that alien fish generally feed lower down the food web. Our findings suggest that the biotic resistance hypothesis, though scale dependent, can result in observable effects in animal communities. Moreover, we also found that the ability to exploit low energy yield food sources could favour the establishment of alien species via avoidance of resistive forces from native taxa.

Refreshing Approaches

Alpine ecosystems occur on all continents, and potentially serve as sensitive indicators of biotic response to environmental change. Because environmental change associated with resource extraction and development is minimal in most alpine areas, biotic changes in the alpine are reflective of “indirect” anthropogenic environmental effects, including changes in climate, atmospheric chemistry, and transmission of ultraviolet radiation. Plant species respond differentially to these environmental changes, related in part to their ability to alter growth rates as resource supply changes and to changes in biotic interactions with neighbors (Theodose and Bowman 1995; Callaway et al. 2002). Thus, changes in plant species composition are likely to herald environmental change in the alpine. Floristic changes have been noted in some alpine areas, potentially associated with climate change (Grabherr et al. 1994), atmospheric pollution (Rusek 1992), and increased N deposition (Korb and Ranker 2001; see Baron et al., this volume for aquatic biotic responses to N deposition).