Ecological Research

  • STATISTICS

    Vol. 36 (2021)
    No. submitted articles: 267
    No. accepted articles: 92

    stat

    Statistics in the 6 months (2021.07-12)
    Days to First Decision (All Manuscripts): 40.9 (days)
    Days to First Decision (Mss. with Final Decisions Only): 37.8 (days)

    Current issue
    (vol. 37, issue 2)
    Days for acceptance:
    118.71 (58–257)
    Days for Early View:
    158.43 (90–320)
    Days for publication:
    227.86 (167–377)

The 19th ECOLOGICAL RESEARCH AWARD

  • Listening to ecosystems: data-rich acoustic monitoring through landscape-scale sensor networks

    Samuel R. P. -J. Ross, Nicholas R. Friedman, Kenneth L. Dudley, Masashi Yoshimura, Takuma Yoshida, Evan P. Economo

    awd_Friedman

    Ecological Research vol.33, No. 1 pp. 135–147

    Keywords: Acoustic monitoring; Biodiversity; Okinawa; Soundscape; Urban–rural gradient


    Abstract Ecologists have many ways to measure and monitor ecosystems, each of which can reveal details about the processes unfolding therein. Acoustic recording combined with machine learning methods for species detection can provide remote, automated monitoring of species richness and relative abundance. Such recordings also open a window into how species behave and compete for niche space in the sensory environment. These opportunities are associated with new challenges: the volume and velocity of such data require new approaches to species identification and visualization. Here we introduce a newly‐initiated acoustic monitoring network across the subtropical island of Okinawa, Japan, as part of the broader OKEON (Okinawa Environmental Observation Network) project. Our aim is to monitor the acoustic environment of Okinawa's ecosystems and use these space–time data to better understand ecosystem dynamics. We present a pilot study based on recordings from five field sites conducted over a one‐month period in the summer. Our results provide a proof of concept for automated species identification on Okinawa, and reveal patterns of biogenic vs. anthropogenic noise across the landscape. In particular, we found correlations between forest land cover and detection rates of two culturally important species in the island soundscape: the Okinawa Rail and Ruddy Kingfisher. Among the soundscape indices we examined, NDSI, Acoustic Diversity and the Bioacoustic Index showed both diurnal patterns and differences among sites. Our results highlight the potential utility of remote acoustic monitoring practices that, in combination with other methods can provide a holistic picture of biodiversity. We intend this project as an open resource, and wish to extend an invitation to researchers interested in scientific collaboration.

  • Plant–soil interactions maintain biodiversity and functions of tropical forest ecosystems

    Kazumichi Fujii, Makoto Shibata, Kaoru Kitajima, Tomoaki Ichie, Kanehiro Kitayama, Benjamin L. Turner

    awd_Fujii

    Ecological Research vol.33, No. 1 pp. 149–160

    Keywords: Biogeochemistry; Biogeography; Dipterocarpaceae; Ferralsols; Weathering



    Abstract Tropical forests are characterized by high biodiversity and aboveground biomass growing on strongly weathered soils. However, the distribution of plant species and soils are highly variable even within a tropical region. This paper reviews existing and novel knowledge on soil genesis, plant and microbial physiology, and biogeochemistry. Typically, forests in Southeast Asia are dominated by dipterocarps growing on acidic Ultisols from relatively young parent material. In the Neotropics and Africa, forests contain abundant legume trees growing on Oxisols developed in the older parent materials on stable continental shields. In Southeast Asia, the removal of base cations from the surface soil due to leaching and uptake by dipterocarp trees result in intensive acidification and accumulation of exchangeable Al3+, which is toxic to most plants. Nutrient mining by ectomycorrhizal fungi and efficient allocation within tree organs can supply phosphorus (P) for reproduction (e.g., mast fruiting) even on P‐limited soils. In the Neotropics and Africa, nitrogen (N) fixation by legume trees can ameliorate N or P limitation but excess N can promote acidification through nitrification. Biological weathering [e.g., plant silicon (Si) cycling] and leaching can lead to loss of Si from soil. The resulting accumulation of Al and Fe oxides in Oxisols that can reduce P solubility through sorption and lead to limitation of P relative to N. Thus, geographical variation in geology and plant species drives patterns of soil weathering and niche differentiation at the global scale in tropical forests.

  • Recent climate change has increased forest winter bird densities in East Europe

    Oleg Askeyev, Arthur Askeyev, Igor Askeyev

    awd_Askeyev

    Ecological Research vol.33, No. 2 pp. 445–456

    Keywords: Climate change; Long‐term number dynamic; Russia; Tatarstan republic; Winter bird monitoring

    Abstract Recent studies on climate change have reported serious impacts on winter forest birds in Western Europe. However, in areas where climate change has caused milder winters and more stable conditions in summer, one would expect resident bird populations to increase, rather than to decrease in winter. The aim of this study was to investigate the impact of climate change on the population dynamics of ten species of Passeriformes in the Tartarstan Republic, Russia. Ravkin's transect method was used to census fixed randomly selected plots spread over a large geographic area at least once every month for the past 26 years. Observers remained the same over the whole period. The abundance of nine species in the first half of the winter and four species in the second half of the winter showed significant increases during the study period. Unlike studies from countries in Western Europe, there were no significant decreases in these species. Significant changes in winter conditions, as well as during the breeding season, and an overall increase in annual temperatures are likely reasons for a significant increase in the number of birds in winter. Greater winter survival, an increase in the survival rate of fledglings and juveniles during the summer, and later onset of winter, are very important determinants of the winter population. Our findings show that numbers of birds in late winter are related to the severity of winter conditions. Our data do not support conclusions that the populations of forest bird species have decreased due to climate change.

  • Highly toxic seeds of the Japanese star anise Illicium anisatum are dispersed by a seed‐caching bird and a rodent

    Tetsuro Yoshikawa, Takashi Masaki, Daichi Hino, Keisuke Ueda

    awd_Yoshikawa

    Ecological Research vol.33, No. 2 pp. 495–504

    Keywords: Ballochory; Plant defense; Secondary metabolites; Toxicity



    Abstract Many field studies on plant seed dispersal teach us that we cannot judge the effective dispersal mode of plants by examining only the morphologies of the fruits and seeds. In the present study, we explored the seed dispersal process of an evergreen tree, the Japanese star anise Illicium anisatum, which is highly toxic, containing neurotoxins in both the fruits and seeds. The fruits exhibit ballochory, a mode of seed dispersal characterized by explosive fruit dehiscence, and the extreme toxicity apparently seems to deter fruit and seed consumption by animals. However, we found that the dispersal distance afforded by this mode was very short (≤ 6 m). In the field, we confirmed that a passerine species, the varied tit Poecile varius, was the only consumer of the seed in foliage, and the bird actively transported seeds or fruits to either cache or consume them. Seeds setting on the forest understory were removed by the small Japanese field mouse Apodemus argenteus, and were also dispersed by this animal. Analysis of seedling spatial distribution revealed that seedlings were highly aggregated near standing trees or fallen logs, suggesting that caching facilitated seed dispersal. This study warns that plant toxicity and the ecological function thereof should not be evaluated based only on limited knowledge of the effects on humans and mammals. Our results pose further questions on the evolution of toxin tolerance in seed‐caching animals and on the mutualism between toxic plants and animals.

  • The seasonal trophic link between Great Cormorant Phalacrocorax carbo and ayu Plecoglossus altivelis altivelis reared for mass release

    Noriyuki Takai, Koh Kawabe, Kenta Togura, Kentaro Kawasaki, Tomohiro Kuwae

    awd_Takai

    Ecological Research vol.33, No. 5 pp. 935–948

    Keywords: Fish fauna; Food chain; Foraging behavior; Stable isotope; Stomach content



    Abstract The feeding ecology of Great Cormorants (Phalacrocorax carbo) during the breeding season in the Kano River basin, central Japan, was examined to clarify the trophic relationship between the cormorants and ayu (Plecoglossus altivelis altivelis) reared for mass release in the river. The ayu was most frequently found in stomachs of cormorants culled during the breeding season, despite relatively poor catch in the year‐round fish fauna research in the watershed. Carbon and nitrogen stable isotope ratios of some ayu individuals extracted from the stomachs of the culled cormorants were similar to the isotopic values of ayu caught in the watershed, whereas the other stomach‐content ayu showed peculiarly high nitrogen isotopic values, clearly distinct from the values of the ayu caught in the watershed, and overlapped with the values of mass‐release ayu. Furthermore, isotopic values of past diets inferred by the isotope analysis of livers of the culled cormorants were closer to the values of the mass‐release ayu, relative to the past diet values inferred by the analysis of the cormorant muscles. This suggests that the food supply from the mass‐release ayu had increased in the breeding season, since the isotopic turnover rate is faster in livers than in muscles. The huge number of formula‐fed ayu released in the watershed create an anthropogenic food chain which is assumed to significantly support the breeding of the cormorants.

  • A paradox of latitudinal leaf defense strategies in deciduous and evergreen broadleaved trees

    Saihanna Saihanna, Tomoe Tanaka, Yu Okamura, Buntarou Kusumoto, Takayuki Shiono, Toshihide Hirao, Yasuhiro Kubota, Masashi Murakami

    awd_Murakami

    Ecological Research vol.33, No. 5 pp. 1011–1017

    Keywords: Chemical defense; Phenol; Physical defense; Plant–animal interactions; Tannin



    Abstract The classical “low latitude–high defense” hypothesis is seldom supported by empirical evidence. In this context, we tested latitudinal patterns in the leaf defense traits of deciduous broadleaved (DB) and evergreen broadleaved (EGB) tree species, which are expected to affect herbivore diversity. We examined the co‐occurrence of leaf defense traits (tannin and phenol content, leaf mechanical strength, leaf dry matter content, leaf mass per area, and leaf thickness) in 741 broadleaved tree species and their correlations with species geographical range in East Asian island flora. We discovered contrasting latitudinal defense strategy gradients in DB and EGB tree species. DB species employed chemical defenses (increasing tannin and phenol content) at higher latitudes and physical defenses (softer and thinner leaves) at lower latitudes, whereas EGB tree species exhibited opposite latitudinal defense patterns. The “low latitude high defense” hypothesis included a paradoxical aspect in chemical and physical defense traits across broadleaved tree species. To reconcile paradoxical defense strategies along the latitudinal gradient, we conclude that interactive correlations among leaf traits are controlled by leaf longevity, which differs between DB and EGB tree species.