Ecological Research最新文献

In subalpine fir wave forests, strips of dead and weakened trees occur perpendicular to the slope next to strips of healthy trees. To reveal the transpiration by weakened Abies veitchii trees exposed to increased atmospheric evaporative demand, we investigated the ecophysiological traits closely related to the growth and transpiration, comparing them with those of the healthy trees and saplings in the fir wave of Mt. Shimagare in central Japan. The transpiration rate (E) was investigated using sap flux sensors to measure heat pulse velocity and compared with the surrogate for the needle water demand, which was computed using a multilayered gas and energy transfer model (modeled E, E_mod). Weakened trees exhibited smaller diameter growth and narrower sapwood than healthy trees, as well as lower heat pulse velocity compared with healthy saplings. However, needle-level traits did not differ significantly between weakened and healthy trees. Needle water potential at midday was as negative as the needle turgor loss point, and the measured heat pulse velocity increased linearly with E_mod but leveled off above a certain E_mod value in weakened trees and healthy saplings, suggesting that trees restricted E to balance the needle water budget. Heat pulse velocity of weakened trees leveled off at E_mod lower than that of healthy saplings, probably due to lower capacity for water supply to the needles. Restriction of E would occur less frequently but be necessary for both weakened and healthy A. veitchii on Mt. Shimagare to avoid hydraulic failure, sacrificing photosynthetic carbon assimilation.

The 10th International Conference on Serpentine Ecology was held in Nancy, France on June 12–16, 2023. The main goals of the conference were to create a platform for the exchange of ideas and experiences and to promote scientific dialogue among scientists from numerous fields who share expertise in the study of ultramafic habitats worldwide. The proceedings of the conference are being published as two Special Issues of Ecological Research, of which this is the second. In this article, we present the major topics and provide some highlights of the contributions to the 10th International Conference on Serpentine Ecology.

The study of fish movement patterns in freshwater ecosystems remains a major focus of contemporary research. Small freshwater fish are known to migrate between tributaries and mainstems at different stages of their life history, helping to avoid local extinctions and maintain genetic diversity. However, fitting small fish species with telemetry equipment is difficult, making it challenging to track their detailed migration history via conventional methods. We evaluated the suitability of otolith isotope analysis for verifying the migration histories of small fish species inhabiting small tributaries. In this study, we compared the ⁸⁷Sr/⁸⁶Sr values in stream water and the otoliths of two fish species (Nipponocypris temminckii and Rhinogobius flumineus) inhabiting small streams. The ⁸⁷Sr/⁸⁶Sr ratios in the stream waters within the study area displayed considerable variation among tributaries. Our findings indicate that only N. temminckii has high dispersal ability, showing movement between tributaries or between tributaries and the mainstem in some locations. In contrast, such movement was not generally observed for R. flumineus. These results show the potential of ⁸⁷Sr/⁸⁶Sr as a tool for estimating the migration patterns of small fishes that inhabit small tributaries.

Wing morphology plays a pivotal role in avian flight capabilities and ecological adaptations across diverse environments. Consequently, wing measurement data are used frequently in comparative analyses and hypothesis exploration to understand avian evolution. Among the parameters representing wing morphology, wingspan and wing area are relatively challenging to obtain compared to simpler measures such as wing length and hand-wing index. This study aimed to enhance accessibility to existing wingspan and wing area data by compiling measurements from 25 literature sources, in addition to unpublished data. The dataset covers 856 species across 95 families and 28 orders. Although the inclusion proportion varies widely among orders, ranging from 0% to 100%, this initial dataset forms a foundation for a more comprehensive database on avian wing morphology. The complete dataset for this abstract published in the Data Paper section of the journal is available in electronic format in MetaCat in JaLTER at https://jalter.diasjp.net/data/ERDP-2024-04. [Correction added on 6 January 2025, after first online publication: The URL for the dataset has been updated.] The dataset will be updated continuously, with the latest version available on figshare in CSV and Microsoft Excel formats (https://doi.org/10.6084/m9.figshare.23537892.v2).

Deep-sea hydrothermal vents are biological hotspots driven by microbial chemosynthetic primary production and characterized by a high proportion of endemic, specially adapted species. Vent communities can be unstable depending on the geological setting, as the underlying geofluid supply may change in location and chemical composition over a decadal timescale. Although the Izu-Ogasawara Arc in Japan is home to many vent fields within an Ecologically or Biologically Significant Marine Area (EBSA), no observations of decadal changes have been conducted. On Mokuyo Seamount, venting was first confirmed by several submersible dives between 1990 and 1993, but only fragmentary information has been published on its biodiversity. Here, we revisited Mokuyo on two dives between 2021 and 2024, three decades after its discovery. We found changes in venting activities, with the fluid supply on the northern caldera wall almost completely waned, while the northeastern face of the central cone has become increasingly active. The northwestern ridge of the central cone was covered in a dense white plume, under which xenophyophores (giant protists) thrive. The first comprehensive faunal sampling at Mokuyo greatly updated the faunal list from three to 18 species. Our results suggest vent communities on the Izu-Ogasawara Arc shift on a decadal scale, providing key baseline data for future conservation planning of the EBSA.

Dissolved organic matter and nutrients released from leaf litter are important cross-ecosystem resources supporting freshwater food webs. Dissolved organic matter supports heterotrophic organisms in freshwater communities. However, the role of nutrients released from leaf litter in the autochthonous production in aquatic ecosystems is not well understood. Therefore, we investigated how dissolved nutrients released from leaf litter affect algal growth, biomass production, and cellular elemental ratios. Specifically, we experimentally examined the response of green algae to nitrogen (N) and phosphorus (P) released from leaf litter of 11 temperate tree species and the degree of deficiency of nutrient elements other than N and P relative to algal demand in these litter leachates by supplementing these elements. We found that algal growth did not significantly increase with dissolved N or P in the leaf leachates. In contrast, algal biomass production increased with dissolved N concentration, regardless of amendment. Algal growth and production limitation by deficiency of elements other than N and P was found only in the leachate of Japanese hemlock, indicating that the concentrations or release efficiencies of these elements in this leaf litter were lower than those of N and P relative to algal requirements. More importantly, leaf litter leachates from different tree species altered algal cell quotas and C:N:P ratios, which would affect secondary production. These results suggest that variations in leaf litter leachate stoichiometry caused by vegetation change would affect the abundance and chemical composition of phytoplankton, and thus the trophic transfer efficiency between phytoplankton and herbivorous zooplankton.

Agromining describes the technique of growing plants to “mine” metals present in naturally enriched or contaminated soils. This technique comprises a series of processes including improvement of soil quality and production of biomass in order to obtain metals from the ash of harvested hyperaccumulators, which can be considered bio-ore. The aim of this study was to evaluate different agronomic practices for Ni agromining of the hyperaccumulator species Odontarrhena chalcidica by analyzing (i) Ni yields and (ii) parameters related to soil fertility, biodiversity, and Ni availability. We tested various types of fertilizers including farmyard manure and assessed cultivation of the hyperaccumulator in either continuous monoculture or cropping in rotation with the legume Vicia ervilia. A 2-year field experiment was established on typical ultramafic Vertisols in eastern Albania. The current study presents the results obtained in the second year of cultivation. After 2 years of agromining, fertilization with animal manure or rotation with the legume improved several soil properties and increased the yield of phytoextracted Ni by four and five times, respectively, relative to non-fertilized plots. The fertilization treatments did not affect the bacterial diversity indexes but significantly impacted the bacterial community structure. We suggest a fertilization regime including the application of pig or chicken manure (at doses equivalent to NPK 260:105:260; 260:390:260, respectively) every 2 years or the implementation of crop rotation with legumes as effective strategies for developing Ni agromining on Vertisols.

Although large carnivores usually prefer large prey, in some situations, they may shift their predation patterns towards smaller but abundant prey. The jaguar (Panthera onca) is a large carnivore capable of changing its diet according to prey and habitat availability. Here, we assessed the temporal and spatiotemporal interactions between jaguars and their prey in the Maracá-Jipioca Islands (Northeastern Amazon, Brazil) through camera traps. We assessed overlapping activity patterns and tested for spatiotemporal segregation/avoidance between jaguars and nine potential prey species. We used a time-to-encounter approach, which consists in calculating the minimum time between prey and jaguar's detections, and vice versa, for each record of preys' species at a specific camera trap station, which translates into aggregation or avoidance behaviors. We found that these insular jaguars are more active in daylight periods when most of their prey are active and in locations used by species that cannot become nocturnal to avoid predators due to morphology constraints. Four prey species (great egret, white-tailed deer, muscovy duck, and black-and-white tegu) presented moderate activity overlapping with jaguars. Agoutis and white-tailed deer seek to spatiotemporally segregate from jaguars, although jaguars did not show spatiotemporal aggregation with any of the evaluated prey. Understanding the spatiotemporal dynamics is essential to establish the islands' trophic network composition and structure. This is fundamental information to efficiently allocate efforts for reducing costs and maximizing benefits in managing this population aiming to protect and conserve it, and consequently, the related ecosystems.

Zoysia japonica, a low growing grass, is tolerant to grazing and trampling. Kinkazan Island in northern Japan is inhabited by sika deer (Cervus nippon). The deer population increased in the 1970s at a shrine garden in the western part of the island, leading to expansion of Zoysia swards around the shrine garden and their colonization of remote open patches. The expansion around the garden is due to elongation of the rhizome, but expansion to remote places may be due to endozoochory by deer. This appears to be a good example of the “foliage is the fruit” hypothesis (the FF hypothesis) proposed by Janzen (1984; American Naturalist 123:338–353). To demonstrate this, we confirmed the expansion of the Zoysia swards and tested the traits of Zoysia by field surveys and indoor experiments. The Zoysia peduncles stood among the leaves, and sika deer fed on both the seeds and leaves. One deer fecal pellet contained about 20 seeds at its peak in June. In the feeding experiment, the survival rate through digestion was 38%. In the greenhouse experiment, the germination rate was 72%. An outdoor experiment showed that germination rates of the ingested seeds were 5% in a dark habitat and 58% in a bright habitat. Zoysia exhibited many of the traits presented by the FF hypothesis, and sika deer functioned as seed dispersal agents. Therefore, the Zoysia—sika deer relationship seems to support the FF hypothesis.

Seagrass provides habitat and resources for various organisms in coastal areas. However, the productivity of a seagrass meadow might vary by its size, which can influence the contribution of primary sources to fauna and the food web structure. This study uses stable isotopes to investigate the contribution of sources to faunas and the associated food web structure in two tropical seagrass meadows. The carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes of primary sources such as mangrove leaf, coastal and riverine particulate organic matter, seagrass material and associated fauna (fish, bivalves, gastropods, crab, shrimp) were investigated from samples collected seagrass meadows of different sizes, at Libong Island and Tharai Island in Thailand. The contribution of the primary sources to the fauna diet showed that seagrass material was the main food source for fauna in both sites. Moreover, the trophic niche did not overlap among the groups of each fauna guild, reflecting the support seagrass provides to resident fauna. The study emphasizes the important role of seagrass as a habitat and feeding ground in tropical coastal ecosystems.