Basic and Applied Ecology最新文献

The introduction of carnivores to islands affects the conservation status of native prey. For two decades, American mink (Neogale vison) has expanded its distribution in the sub-Antarctic archipelago of Austral Patagonia, while preying on nests of solitary ground-nesting birds. Here, upland geese (Chloephaga picta) and flightless steamer ducks (Tachyeres pteneres) are naïve to such predation risk because of the lack of native terrestrial predators. We used nest occupancy models to reveal preferred breeding habitats of those two ground-nesting waterbirds to prioritize areas for future mink control programs. We searched for nests along 80 transects on Navarino Island, southernmost Chile, and 11 transects on 10 nearby islets (3 ± 2.9 ha). Our results showed that islets were essential for breeding in comparison to the main island (5.3 nests/km versus 0.8 nests/km, respectively). The occupancy models revealed that islets were particularly important for flightless steamer ducks, endemic to western Patagonia. As breeding habitat, upland geese preferred medium-dense shrubland, and flightless steamer ducks preferred rocky coastlines. Nest detection was negatively affected by dense vegetation and, in the case of the upland geese, towards the end of the survey. Ten camera traps (n = 385 trap nights) revealed mink presence on all islets, highlighting their capacity to swim in cold water, up to 340 m distance from the main island. We conclude that islets represent breeding refuges for ground-nesting waterbirds and therefore advocate allocating resources for mink control during the warm season on islets. We also provide predictive maps of nesting habitat preference of upland geese and flightless steamer ducks for conservation managers to focus their often scarce human and financial resources on areas critical for breeding. Finally, we argue that detection probability should be an integral part of bird breeding studies, which can be methodologically achieved through targeting transects, not nests, as sample units.

Plant-pollinator interactions are key for the reproduction of wild plants and for food security. However, the role nocturnal pollinators play in wild plant communities is not yet clear. Specifically, it has rarely been studied whether nocturnal pollinators are comparable to diurnal ones in the pollination services they deliver in plant communities. We tested whether nocturnal pollinators have the potential to provide high pollination services to the plants they visit by carrying high conspecific pollen loads. We studied pollen loads carried by nocturnal and diurnal pollinators captured over 24-hour cycles in co-flowering plant communities in Swiss ruderal meadows. Pollen load was less diverse at night, and the proportion of conspecific pollen carried by nocturnal pollinators was higher than that of diurnal ones. Because the majority of plant species visited at night were also visited during the day, floral resource availability could drive the observed patterns in pollen load and amount of conspecific pollen. Nevertheless, nocturnal pollinators do not only carry pollen but can remove and potentially deposit conspecific pollen to the plants they visit. Therefore, pollinators active at night might be an important pollination vector for more plant species than previously thought and should not be neglected in pollination studies.

As the globe gets more urbanised, the question about how natural biodiversity is structured in cities becomes increasingly pertinent. To contribute to an answer, we studied species richness and spatio-temporal structure of bees in a North European metropolitan area. A gradient of 13 sites in the city of Aarhus, Denmark, was censused from April to September 2016. Forty species, i.e. 29 solitary species (40 % of all individuals), ten Bombus species (28 %), and Apis mellifera (32 %), were sampled monthly in pan traps. (i) Information about species traits was extracted from the literature, and trait values were correlated and used to characterize the fauna. Most were soil-nesters, pollen generalists, and common. (ii) Habitat diversity within five concentric circles with trap at the centre and radii from 50 m to 1000 m was related to bee α diversity. The relationship was significant only within 1,000 m for all bees and for bumblebees. Solitary bee diversity was uncorrelated with habitat diversity at all spatial levels. (iii) Spatio-temporal structure was analysed as two networks, one for bees linked to sites, and one for bees linked to months. Link patterns were analysed for levels of nestedness, modularity, and spatio-temporal β diversity. The two networks were weakly and non-significantly nested, but strongly modular, being composed of five and four modules of co-occurring bees, respectively. (iv) Finally, we studied total β diversity, β_TOTAL, being the sum of species turnover, β_TURN, and species loss/gain or nestedness, β_NEST. For both site and season, β_TURN was higher than β_NEST, and site β_TOTAL was higher than season β_TOTAL. One reason for this metacommunity structure may be a high spatio-temporal habitat patchiness, sustaining a rich biodiversity. Thus, a few large areas may not compensate for the loss of several small patches. Consequently, establishment of many green, even small habitats is recommended.

Tens of thousands of plant species globally are harvested to varying extents as non-timber forest products (NTFPs). Local populations of many NTFPs face significant pressures from harvesters, often leading to calls for harvesting guidelines to promote sustainable offtakes. However, most studies to determine sustainable harvest levels implicitly assume that the entire population is available to harvesters. Yet, certain areas or portions of particular NTFP populations outside of protected areas may not be open to harvesting because they are in some sort of cultural or spatial refuge. Using a mixed-methods approach we assessed the prevalence and efficacy of refugia for 70 NTFP plant species at seven communal land sites in south-eastern South Africa. Based on reports from local harvesters, approximately 10 % of the 70 species had part of their population in a refuge. For most of these, populations within a refuge showed lower levels of harvesting and were in a better condition than adjacent populations not in a refuge. These results demonstrate that studies assessing the sustainability of harvesting of NTFP populations should account for whether refugia are present.

Biological invasions are a major threat to biodiversity because of invasive alien species’ high population growth rates and spread in new ranges. The inherent superiority hypothesis states that particular characteristics of alien species cause them to perform better than native species. Using a meta-analysis of 127 studies and more than 900 experimental observations comparing alien and native plant performance, we investigated, whether: (1) studies comparing alien and native performance generally support the inherent superiority hypothesis; (2) the direction and magnitude of superiority depend on the choice of performance measure; and (3) it depends on other aspects of the study design or species. We found that the inherent superiority hypothesis was overall supported, although the strength of this result depended on the chosen measure of effect size (a significant effect for the standardized mean difference SMD (Hedge's g) but not for the log response ratio LRR). Alien plant species were more likely to be found superior compared to natives if performance was measured in terms of growth, reproduction or response to natural enemies. Measuring survival or abundance was less likely to result in alien superiority, while for measurements of physiology and response to mutualists results were mixed. Furthermore, aspects of experimental design, selection and number of study species played an important role. We thus quantitatively showed across a broad range of conditions how choice of performance measure and experimental design affect the direction and magnitude of alien superiority found in small-scale studies. Furthermore, our review pointed out a lack of studies that assessed population growth as a direct determinant of true superiority. Conducting studies using performance measures relevant for superiority, while also considering other potentially important factors such as residence time, will shed more light on how common true alien superiority is and in which contexts it is to be expected.

As important terrestrial ecosystems on the Qinghai‒Tibet Plateau with important ecological and economic value, alpine meadows in some regions are in a degraded state due to climate change and unsustainable grazing. Due to the fragile ecological environment, exploring sustainable restoration models of degraded alpine meadows using close-to-nature restoration measures is the direction of ongoing efforts. Thus, in this study, three close-to-nature restoration measures, namely, manure application (M), Poa annua, Elymus dahuricus, and Puccinellia distans mixed with non-tillage reseeding (R), and the combined treatments (MR), were used to restore degraded alpine meadows from 2019 to 2021. The results showed that the M and MR treatments significantly enhanced plant biomass and reduced forbs dominance, thus improving community structure. Moreover, the M and MR treatments significantly affected plant and bacterial alpha diversity. However, the three restoration measures did not alter the correlation between the plant and bacterial communities. Furthermore, these three measures resulted in a significant increase in the plant carbon:nitrogen ratio and a significant decrease in the nitrogen:phosphorus ratio, while neither the plant carbon:phosphorus ratio nor the soil stoichiometric ratio changed significantly, indicating that nitrogen limitation was an important factor that limited the recovery process of the alpine meadows. The structural equation model indicated that the plant nitrogen:phosphorus ratio may regulate the response of plant and bacterial diversity to different restoration measures in alpine meadows. Our findings emphasize that the management of degraded alpine meadows using close-to-nature restoration measures should be a long-term effort, with more attention given to changes in the nitrogen content of meadow ecosystems.

Over the last decades, the use of irrigation in vineyards has grown exponentially in response to climate change. In the Mediterranean region, irrigation is the most widely used method of preventing water stress and high sugar content in grapes. However, little is known about potential irrigation effects on biodiversity. This study aims to understand the effect of irrigation on inter-row vegetation, on the abundance of beneficial arthropods and on the predation of pest insects. In the Luberon region of South-Eastern France, nine irrigated and nine non-irrigated vineyards were analysed. Drip irrigation was applied only during the two driest months of the growing season. We found lower flower cover in irrigated vineyards but no difference in species richness and total vegetation cover. Similarly, abundances of several beneficial arthropods were directly affected by irrigation, such as crab spiders, ladybirds, ladybird larvae and parasitic wasps. Structural equation modelling (SEM) revealed that negative irrigation effects on these arthropods were mediated by negative effects on flower cover. Predation rates were also lower in irrigated vineyards but only during daytime. Grapevine yield was not affected by irrigation. Experiments manipulating water availability under controlled conditions may help to understand this surprisingly strong effect of irrigation on flower cover and beneficial arthropod abundance.

Scavengers benefit from carrion and simultaneously provide essential ecosystem services. To assess benefits and risks that carrion might bring, it is crucial to understand ecosystem-specific scavenger communities. Carrion research has mostly focussed on ungulate carcasses and has rarely explored the effects of carnivore carcasses, which can be critical to understanding disease transmission pathways. Therefore, using red fox, roe deer and red deer carcasses, we investigated factors that affect facultative vertebrate scavenger assemblages visiting carnivore and herbivore carcasses in a temperate forest ecosystem. Due to potentially increased disease transmission risk associated with carnivore carrion, we predicted that carnivore carcasses would be visited less and have a reduced visiting species composition compared to herbivore carcasses. Further, we expected red foxes to exhibit less consumption behavior of conspecific carcasses. We placed 22 red fox and 22 herbivore carcasses in a temperate montane protected area in Central Europe, the Bavarian Forest National Park, and analyzed the visits of all species and the consumption behavior of red fox at carcasses to understand whether these depended on carcass type. We found no significant effects of carcass type on visitation rates, visiting species composition, or red fox behavior. Cannibalism of foxes was common and, when controlling for confounding factors, e.g., elevation, temperature, and scavenging seasonality, the predicted consumption rate of red fox at conspecifics was higher than at herbivore carrion. Foxes appeared to consume conspecifics earlier than herbivore carrion, but the difference was not significant. At the very least, our results show that carnivore carcasses and fox behavior, including cannibalism, could provide a pathway for disease transmission. We thereby provide a first impression of the patterns of vertebrate scavenger assemblages at different carcass types in a temperate ecosystem and show that red fox behavior might precipitate a disease transmission pathway.

Oil tree peony is a unique woody oil crop found exclusively in China. Its seed oil is a highly nutritious edible vegetable oil. However, its seed production varies greatly and is often low. Oil tree peony is a plant that relies on insects for pollination, but inadequate pollination is a common occurrence. In this study, we focused on the Paeonia ostii ‘Fengdan’ species and conducted a five-year study (from 2017 to 2022) in Luoyang, China. Our objective was to assess the extent of pollination deficiency and dependence, as well as quantify the contribution of supplemented bumblebees (Bombus terrestris) to the yield of oil tree peony. We also examined the effect of supplemented bumblebees on the temporal variation in yield through various pollinator survey designs, including supplemented bumblebees (BP), open pollination (OP), pollinator exclusion (EP), self-pollination treatments (SP), and artificial cross-pollination (CP). The results revealed a medium pollination deficit (D = 0.50) at the study sites for three consecutive years from 2020 to 2022, indicating limited pollination for oil tree peony under natural conditions. Importantly, BP significantly compensated for this deficiency (D = 0.22). Over the course of five years, BP increased the yield of oil tree peony by 82.87% on average compared to EP. Furthermore, the yield variation coefficient of EP (CVt=0.20) increased by 100% compared to BP (CVt=0.10). And we also observed significant variability in other yield parameters. Additionally, oil tree peony production was reduced by 44.24% in the absence of flower visitors, and the dependence on BP reached a “high” level. The fatty acid content in the seed oil did not show significant differences across treatments, indicating its stability. Overall, our pollination practices demonstrate that supplementing bee pollination can provide sufficient and stable pollination services, resulting in a higher and more stable yield of oil tree peony seeds.

The security of the Earth system has been extensively discussed through the concept of planetary boundaries, which hypothesizes the Anthropocene as the crisis for pushing environmental variables beyond safe limits. Cities, as burgeoning population centers, warrant heightened attention to issues surrounding planetary boundaries and ecological security. While groundwork has been laid for environmental change detection, the acoustic or soundscape perspective is rarely considered. This paper presents abundant empirical evidence supporting the feasibility of leveraging the soundscape as a valuable lens for exploring ecosystem structures, functions, and their contribution to human well-being. Particularly, it proposes spatialized soundscape maps as practical tools to implement this innovative perspective. We elaborate on two key aspects: (i) soundscape as a reflection of ecosystem evolution, enabling evaluation of ecosystem structures, interactions, and the ecosystem's functions; (ii) soundscape has the attribution of providing cultural services, allowing assessment of its impact on human health. Consequently, we propose two paradigms: (i) “security in soundscape” and (ii) “security of soundscape”, thereby initiated the concept of “soundscape for security”. Furthermore, we outline two generalized pathways: (i) soundscape monitoring, encompassing long-term strategies for real-time tracking of ecosystem evolution, and (ii) soundscape perception, involving detailed surveys to investigate perception and public participatory sensing for large-scale evaluation of ecosystem cultural services. We argue that integrating soundscape considerations holds promise in urban ecological security initiatives and the pursuit of sustainable cities. Moving forward, collective efforts among academics are crucial to establish widely accepted protocols to maximize the value of soundscape for urban ecological security.