Altered Trends in Spring- and Autumn-Flowering Species in Japan in Response to Global Warming

Preface: Functional biogeography in Japanese cedar

Carbon stock projection for four major forest plantation species in Japan

Carbon sequestration via afforestation and forest growth is effective for mitigating global warming. Accurate and robust information on forest growth characteristics by tree species, region, and large-scale land-use change is vital and future prediction of forest carbon stocks based on this information is of great significance. We presented the forest age–carbon density functions of four major forest plantation species in Japan: Cryptomeria japonica, Chamaecyparis obtusa, Pinus spp., and Larix kaempferi. We then investigated the differences in the carbon sequestration potential of forests, including wood production, between five forestry practice scenarios with varying harvesting and afforestation rates, until 2061. For all four forest types, the estimates of growth rates and past forest carbon stocks were higher than those considered thus far. The predicted carbon sequestration from 2011 to 2061, assuming that 100% of harvested carbon is retained for a long time, twice the rate of harvesting compared to the current rate, and a 100% afforestation rate in harvested area, was three to four times higher than that in a scenario with no harvesting or replanting. Our results suggest that planted Japanese forests can exhibit high carbon sequestration potential under the premise of active forest management with technology development.

This study investigated the impact of global warming on Japanese wind energy resources and their short-term variations using the large ensemble d4PDF dataset, which consists of dynamically downscaled historical and +4K future climate projections. The capacity factor under the future and present climate was estimated from an idealized power curve based on hourly near-surface wind speeds. The +4K warming future climate projections showed significant changes in wind energy resources that varied both regionally and seasonally. The wind energy potential was projected to slightly increase (decrease) from winter to spring over northern (southern) Japan and decrease from summer to autumn over most of Japan. The projected annual production decreased by about ~5% over Japan in response to climate change. The frequency of wind ramp events also decreased in the latter seasons. The relationship to synoptic weather was investigated using self-organizing maps, whereby weather patterns (WPs) over the region in the present and future +4K climate were classified for a two-dimensional lattice. Future probabilistic projections of WPs under the global warming scenario showed both increases and decreases in the frequency of different WPs, with corresponding advantages and disadvantages for wind power generation with regard to future changes in capacity factors in Japan. The importance of these frequency changes on the total change was further assessed by separating the dynamical and thermodynamic contributions.

We analyzed a large ensemble dataset called the database for Policy Decision Making for Future climate change (d4PDF), which contains 60-km resolution atmospheric general circulation model output and 20-km resolution dynamical downscaling for the Japanese domain. The increase in moisture and precipitation, and their global warming response in June–July–August were described focusing on the differences between Hokkaido and Kyushu; Hokkaido is cool and dry and Kyushu is hot and humid in the current climate. The results suggested that the specific humidity increased almost following the Clausius Clapeyron relation, but the change in stationary circulation suppressed the precipitation increase, except for in western Kyushu. The + 4 K climate in Hokkaido would be as hot and humid as the present climate in Kyushu. The circulation change related to the southward shift of the jet stream and an eastward shift of the Bonin high weakened the moisture flux convergence via a stationary field over central Japan including eastern Kyushu. The transient eddy activity counteracted the increase in humidity, so that the moisture flux convergence and precipitation did not change much over Hokkaido. Because the contribution of tropical cyclones to the total precipitation was at most 10%, the decrease in the number of tropical cyclones did not explain the predicted change in precipitation.

Correction to: Summertime precipitation in Hokkaido and Kyushu, Japan in response to global warming

Global warming can alter the spatial and temporal distribution of fish stocks, which often has an impact in commercial fisheries. Better anticipation and preparations for the effects of global warming on fisheries are necessary. In this review paper, we examined and summarized the past predictions of the effects of global warming on commercially important fishes around Japan and contrasted with recent information

The impact of climate change on cherry trees and other species in Japan

Ectomycorrhizal (ECM) symbioses are indispensable for the establishment of host trees, yet available information of ECM symbiosis in alpine forests is scarce. Pinus pumila is a typical ice age relict tree species in Japan and often forms monodominant dwarf vegetation above the tree line in mountains. We studied ECM fungi colonizing P. pumila on Mt. Norikura, Japan, with reference to host developmental stages, i.e., from current-year seedlings to mature trees. ECM fungal species were identified based on rDNA ITS sequences. Ninety-two ECM fungal species were confirmed from a total of 2480 root tips examined. Species in /suillus-rhizopogon and /wilcoxina were dominant in seedling roots. ECM fungal diversity increased with host development, due to the addition of species-rich fungal lineages (/cenococcum, /cortinarius, and /russula-lactarius) in late-successional stages. Such successional pattern of ECM fungi is similar to those in temperate pine systems, suggesting the predominant role of /suillus-rhizopogon in seedling establishment, even in relict alpine habitats fragmented and isolated for a geological time period. Most of the ECM fungi detected were also recorded in Europe or North America, indicating their potential Holarctic distribution and the possibility of their comigration with P. pumila through land bridges during ice ages. In addition, we found significant effects of soil properties on ECM fungal communities, which explained 34.1% of the total variation of the fungal communities. While alpine vegetation is regarded as vulnerable to the ongoing global warming, ECM fungal communities associated with P. pumila could be altered by the edaphic change induced by the warming.

The distribution of Phellinus noxius is currently limited to tropical and subtropical regions of Southeast and East Asia, Oceania, Central America, and Africa. The ability of this pathogen to produce disease in temperate climates is unknown. We examined the pathogenicity of Phellinus noxius on four important conifer plantation species grown under temperate conditions in Japan. The inoculation experiment with two isolates of P. noxius from Japan demonstrated clear fungal pathogenicity on the four conifer species, 3 months post-inoculation. Typical disease symptoms ranged from wilting, leaf chlorosis and necrosis, and defoliation resulting in the eventual death of most saplings. Mortality rate varied depending on tree species and the fungal isolate used. The results suggest that the possibility of serious damage if P. noxius invades the temperate zone of Japan (e.g., Kyushu and/or Honshu) from subtropical areas of Japan such as the Ryukyu Islands or foreign countries as global warming progresses.

In this paper, we present an investigation of interspecies differences in transpiration of the 2 most common plantation forest tree species in Japan, both in the family Cupressaceae with different northern limits of native distribution, Japanese cypress (Hinoki; Chamaecyparis obtusa Sieb. et Zucc.) and Japanese cedar (Sugi; Cryptomeria japonica D. Don). The stem sap flow rate was measured in 2 nearby stands of similar leaf area index in a 42‐year‐old plantation. Single‐tree and stand‐scale transpiration rates (Etre and Esta, respectively) were observed during an ideal autumn environment. At the stand scale, mean sap flux density of Hinoki was greater than that of Sugi, whereas total sapwood area per ground area was smaller in Hinoki than Sugi. Because the 2 variables had counterbalancing effects on transpiration, Esta of Hinoki was similar to (94% of) that of Sugi. This offset was also found between the mean Etre of the 2 species. Esta was similar between the stands from May to October, whereas Esta of Sugi was notably greater than that of Hinoki from February to April. During these 3 months, the difference in cumulative Esta was 21.7 mm, which accounted for 79% of the difference in annual Esta between Hinoki and Sugi (192 and 219 mm/year, respectively). We found that canopy conductance (Gc) and its sensitivity to the mean vapour pressure deficit during daylight hours in Sugi were particularly high in early spring, whereas those in Hinoki shifted gradually throughout the growing season. This difference was related to the optimal temperature of Gc in Sugi, which was approximately 10 °C lower than that in Hinoki. Our results suggest that plantations of water‐conserving species such as Hinoki produce timber slowly but yield water resources generously. Moreover, for plantations of trees sensitive to high temperature, such as Sugi, managers should be concerned about possible future decline caused by anticipated global warming.

Cryptomeria japonica (common name is sugi or Japanese cedar) is the most important forest tree species in Japan, and its wood is used for house construction, wooden ships, wooden barrels, and many articles for daily use. Artificial plantation of this species is thought to begin more than 500 years ago, and sugi currently covers 44% of Japanese artificial forest. Though discarded wood in forest by thinning or after harvesting is a valuable biomass, most of the discarded wood is left at forest, not used for materials of biomass energy. A traditional breeding program for sugi was started in the 1950s, and ca. 3600 plus trees (healthy individuals with superior growth performance) had been selected mainly in artificial forests. A current problem due to sugi is allergic reactions to pollen (pollinosis). A nationwide epidemiological survey showed that 26.5% of the Japanese population suffers from pollinosis due to sugi pollen. To address this problem, individuals with low male flower setting have been selected from plus trees. Male-sterile mutants were also discovered, and artificial crosses between the mutants and plus trees have been attempted. This review summarizes sugi breeding, concentrating on biotechnological research (DNA marker and genetic transformation). Genetic improvement in artificial forests increases their forest economic value, leading to sustainable forest management. Sustainably managed forests accumulate continuously renewable carbon in their trees, contributing to mitigation of global warming.

We surveyed 110 Saccostrea oysters sampled from southern Kagoshima Bay and Wakayama Prefecture to monitor the species diversity of marine benthos using morphological features and DNA barcoding. Prior to the survey, we re-identified 55 Saccostrea oysters sampled from the Yaeyama Islands, a hot spot for Saccostrea species in Japan. Analysis of partial nucleotide sequences from the mitochondrial large subunit of ribosomal DNA (LSrDNA) led to the discovery of the Indo-West Pacific rock oyster S. cucullata-F in Kagoshima Bay, and S. cucullata-C and S. cucullata-F in Wakayama Prefecture. This is the first record of the Indo-West Pacific rock oyster in mainland Japan (Hokkaido, Honshu, Shikoku and Kyushu Islands). We postulate that there may have been a northward shift in the distribution patterns of the species due to global warming, these Pacific rock oysters are relic species from the Middle or Late Pleistocene, or the non-indigenous species were introduced by oil tanker or other industrial activities.

To prepare and manage urban greenspace for a hotter future, we must select trees that can tolerate or acclimate to high temperatures. Here, we compared tolerance and acclimation to high temperatures among nine urban tree species in Japan. Saplings were exposed to heat from different times (early and mid-summer) during the growing season in a greenhouse. With the exception of Ginko, heating in early summer did not affect whole-tree health, suggesting that most urban tree species may be able to acclimate to higher temperatures during the early growing season. However, continued exposure to higher temperatures, as well as heating from mid-summer, had negative effects on tree health, leading to wilting/browning, especially for evergreen broadleaved species whose leaves mature slowly. Cornus florida, Styrax japonicus and Morella rubra were the most vulnerable to heating, such that all heated saplings had died by the end of summer. At the leaf level, leaf maturation of the deciduous species and Morella was negatively affected by heating, whereas that of Eurya emarginata and Euonymus japonicas were not affected. These two species also showed heat tolerance, having a higher T50 (temperature where leaf quantum yield declined to 50% of maximum value due to heat stress) compared to other species, as well as heat acclimation, where T50 was higher for the heated saplings compared to the control. Our results indicate that, while some species that cannot recover from heat damage in early summer could die, others can acclimate to sustained high temperatures, as well as to late summer heat. As heatwaves are expected to become more frequent and severe due to global warming, tree species need to be screened individually to assess their ability to tolerate or acclimate to high temperature.