Ecological Research
- ONLINE SUBMISSION
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STATISTICS
Vol. 32 (2017)
No. submitted articles: 536
No. accepted articles: 126
Current issue
(vol. 33, issue 2)
Days for acceptance:
213 (81–425)
Days for online-first:
226 (93–409)
Days for publication:
290 (141–439)
The 15th ECOLOGICAL RESEARCH AWARD
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Responses of carbon and oxygen stable isotopes in rice grain (Oryza sativa L.) to an increase in air temperature during grain filling in the Japanese archipelago
Ecological Research vol.29, No. 1 pp. 45–53
Keywords: Carbohydrate; Climate change; Koshihikari rice; Minimum air temperature; Oxygen isotope discrimination
AbstractStable isotopic compositions of carbon (δ13C) and oxygen (δ18O) in plants reflect growth conditions. Therefore, these isotopes might be good indicators of changes in environmental factors, such as variations in air temperature caused by climate change. It is predicted that climate change will lead to a greater increase in minimum air temperatures (primarily during the night) than in maximum air temperatures (primarily during the day) in many parts of Japan. In the present study, we investigated whether the δ13C and δ18O of the rice grain Koshihikari (Oryza sativa L.) from the northern latitudes (30.49°–37.14°) of Japan reflect variations in air temperature during grain filling and are related to the yield and proportion of first-grade rice (<15 % transparency, roundness, and cracking) as an indicator of quality. We revealed that rice δ13C was not correlated with mean maximum or minimum air temperatures for each prefecture. By contrast, rice δ18O was positively correlated with mean minimum air temperature, suggesting that rice δ18O reflects changes in night air temperature. We further showed that an increase in the mean minimum air temperature during grain filling had a negative effect on rice yield and quality. Our findings indicate that the δ18O of rice grain may be a good indicator of physiological changes in response to minimum air temperatures during grain filling.
Robust optima and tolerance ranges of biological indicators: a new method to identify sentinels of global warming
Ecological Research vol.29, No. 1 pp. 55–68
Keywords: Ecological optima; Optimum range; Tolerance range; Box-plot; Global warming; Biological indicator; EU-WFD
AbstractThis study aims to introduce the robust optimum (RO) method as an alternative to the classical weighted averaging (WA) method for estimating the ecological optimum as well as the optimum and tolerance ranges of a taxon with respect to an environmental variable in limnological studies. The RO method is based on robust location and scale estimates rather than on the mean and the standard deviation used by the WA method. The results of our study support the well-known fact that the presence of outliers and the asymmetry of the distribution of the environmental variable might cause a significant effect on the WA-calculated ecological optimum as well as on tolerance ranges. We compared both methods through the identification of potential biological indicators of global warming. Biological data included several benthic, oligostenotherm macroinvertebrate families inhabiting the Jucar River Basin (JRB, eastern Spain). The results of this comparison suggest that the RO method is more appropriate for estimating the distribution of taxa and, consequently, that it provides more realistic information for identifying potential sentinels of global warming in running aquatic systems. Currently, the identification of such sentinels is a goal for several environmental protection laws, such as the European Union Water Framework Directive.
Biological cycle of silicon in moso bamboo (Phyllostachys pubescens) forests in central Japan
Ecological Research vol.29, No. 3 pp. 501–510
Keywords: Biogenic silicon; Phytolith; Biogeochemistry; Biomass; Turnover
AbstractSilicon (Si) has various biogeochemical functions, such as regulating soil formation and species composition, not only in terrestrial ecosystems but also in aquatic ones. Bamboo stands accumulate large quantities of amorphous Si. Evaluating Si dynamics in moso bamboo (Phyllostachys pubescens) forests, which are currently spreading through eastern Asia, is important in understanding their biogeochemical function as a supply source of phytoliths. We conducted a study on the organic accumulation and biological cycle of Si in three P. pubescens stands in central Japan with different site characteristics. The amounts of Si accumulation aboveground and underground were 200–360 and 180–460 kg/ha, respectively. These values indicate that Si accumulation underground was comparable to that aboveground. Silicon supply to the forest floor through litterfall was 77–330 kg/ha/year corresponding to 165–706 kg/ha/year as phytoliths (SiO2), and 72–88 % was supplied as leaf litter. These results showed that a huge biogenic Si pool derived from bamboo plants exists in the floor of bamboo forests. Furthermore, we estimated the Si turnover time in P. pubescens forests as being 1.3–12.2 years, although this variation may depend on forestry conditions such as soil water content or stem density.
Digging deep to open the white black box of snow root phenology
Ecological Research vol.29, No. 4 pp. 529–534
Keywords: Alpine snow bed; Anatomy; Life history; Nutrient uptake strategy; Snow roots; Winter ecology
AbstractSnow roots are specialized structures recently discovered in the Caucasian alpine snow-bed plant Corydalis conorhiza. They form extensive networks that grow into snow packs against gravity, most probably to gather nitrogen from snow. Here we test the hypothesis that snow roots are true winter organs, i.e., they should already start growth early in winter to lay down the infrastructure for N capture from snow packs well before their melt-out. This would require winter surface and soil temperatures continuously close to or above freezing. Excavations of snow roots from snow packs in January and May, accompanied by temperature recordings and anatomical observations, supported our hypothesis. These findings complete the annual cycle of snow root phenology. They also emphasize the evolutionary and ecological significance of these specialized winter organs. Moreover, their likely association with a particular abiotic temperature and snow regime will facilitate the search for snow roots in other species.
Dimorphism of the seed-dispersing organ in a pantropical coastal plant, Scaevola taccada: heterogeneous population structures across islands
Ecological Research vol.29, No. 4 pp. 733–740
Keywords: Coastal plant; Dimorphism; Ecological differentiation; Scaevola taccada; Seed dispersal
AbstractScaevola taccada is characterized by dimorphic fruits, with one type having cork and pulp (C-morph) and the other type having only pulp (NC-morph). Although within-individual dimorphism has not been observed, both morphs can occur at the same sites. The cork floats on seawater, and the pulp is eaten by birds. Thus, the morphs may have different seed dispersal abilities, via sea currents and birds, respectively. This study aimed to determine the functional characteristics of the dimorphic fruits. First, the potential seed dispersal ability of sea currents and birds was compared between the two fruits morphs by conducting a floating test and by measuring the proportions of different parts of the fruits, respectively. Next, the frequencies of the two morphs across different substrates (beaches, rocks, and cliffs) in the southern islands around Japan were analyzed. Most C-morph fruits remained floating for more than 180 days in a seawater tank, whereas all NC-morph fruits sank after approximately 1 week. The NC-morph fruits had a more pulp volume and less indigestible material than the C-morph fruits. Although both types of plants were found on many islands and all substrates, the C-morph was dominant on beaches, whereas the NC-morph was most frequent on cliffs. The frequencies of the morphs on different substrates might be influenced by the differences in their seed dispersal abilities. The two morphs may differ in fitness on different substrates. These findings improve our understanding of plant adaptations for dispersal.