The early Cambrian pentamerous microfossil Olivooides/Punctatus in South China, which is characterized by a diagnostic stellate tubular apex, has been well-known for its almost complete development sequence that can b...The early Cambrian pentamerous microfossil Olivooides/Punctatus in South China, which is characterized by a diagnostic stellate tubular apex, has been well-known for its almost complete development sequence that can be confidently traced from embryos and hatched juveniles, to conical adults. However, its zoological affinity remains highly controversial. Here we describe the internal microanatomic structures of the soft-body inside the peridermal theca of Olivooides multisulcatus Qian, 1977, including interradial pairs of tentacles, adradial and perradial frenula, perradial oral marginal lappets and twins of perradial gastric saccule-like humps as well as a circular velarium with striated coronal muscles. Particularly, one specimen shows bifurcated velarial canals along the bell aperture. Both the components of the soft-body and the external theca （or cyst） are arranged in perfect pentaradial symmetry. These characteristics are more compatible with those of living cubomedusans and co-occurring Cambrian athecate embryonic cubozoans. Concerning the presence of peridermal theca, Olivooides most likely represents an extinct thecate stem-group cubomedusae but devoid of both perradial eyes and specialized pedalia. The well-grown soft body inside the peridermal tube displays a set of mixed features of both polyp and medusa.展开更多
Peatland in Southeast Asia has an important function in the provision of ecosystem services such as carbon sink, climate regulation, water supply, biodiversity, and others. Recurrent fires in the peatland, especially ...Peatland in Southeast Asia has an important function in the provision of ecosystem services such as carbon sink, climate regulation, water supply, biodiversity, and others. Recurrent fires in the peatland, especially in Indonesia, have changed peatland functions from carbon sequestration to carbon emission, causing severe environmental and economic problems. Fire prevention requires an understanding of the factors affecting fire in peatland. We compared fire occurrences in 2014 between different land cover types, land management systems, landholders, and proximity to roads and canals in Riau Province, Indonesia. Remote sensing and field data were collected and analyzed. Shrubland was the most fire-prone land cover, while plantations and mangrove forests were the least. Shrubland has high fire occurrence regardless of land management and landholder type. Peat swamp forests that are allowed to be utilized were more fire-prone than conserved peat swamp forests. Oil palms from unregistered companies had more fires than those from registered companies and smallholders. Coconut and sago plantations from companies had more fires than smallholder cultivation. Proximity to roads and canals affects the occurrence of fires in peat swamp forests;however, proximity had less of an effect on fire occurrence in shrubland. The high percentage of burned areas in shrubland showed that land cover was a major factor that affects fire in peatland, followed by land management, landholders, and proximity to roads and canals. These findings indicate the importance of law enforcement and land management systems, management schemes by different landholders, and the spatial arrangement of land cover, roads, and canals for integrated peatland management and restoration of shrubland into peat swamp forest and other fire-resistant land cover types with sustainable production.展开更多
Especially in recent years, deep learning has become a very effective tool for object identification. However, in general, the automatic object identification tends not to work well on ambiguous, amorphous objects suc...Especially in recent years, deep learning has become a very effective tool for object identification. However, in general, the automatic object identification tends not to work well on ambiguous, amorphous objects such as vegetation. In this study, we developed a simple but effective approach to identify ambiguous objects and applied the method to several moss species. The technique called chopped picture method, where teacher images are systematically dissected into numerous small squares. As a result, the model correctly classified 3 moss species and “non-moss” objects in test images with accuracy more than 90%. Using this approach will help progress in computer vision studies for various ambiguous objects.展开更多
Vertical structure is important for understanding forest environment, yet difficult to characterize, especially in temperate heterogeneous forests where the structure is complex. This study used data from a small-foot...Vertical structure is important for understanding forest environment, yet difficult to characterize, especially in temperate heterogeneous forests where the structure is complex. This study used data from a small-footprint airborne laser scanning (ALS) to estimate vegetation coverage in four stratum ranges in a warm temperate forest in Japan: >12 m, 8 - 12 m, 4 - 8 m, and 0 - 4 m in height. Field data were collected in 17 broad-leaved and 12 coniferous sample plots, consisting of the proportion of vegetation cover in each stratum range. The field and ALS measurements were conducted in summer, during leaf-on conditions. Using echo attributes (first, last, intermediate, and only), we calculated the vegetation coverage index (VCI) at 1-m height intervals. The cumulative sum of the VCI (CUMVCI) was then computed and compared with field observations. Linear regression analysis showed that the ALS data gave reasonable estimates of vegetation coverage in the upper two or three stratum ranges in broad-leaved stands, and in the upper two stratum ranges in coniferous stands. The model gave reproducible estimates until approximately 95% of the total returns had been applied. We conclude that ALS data can provide useful information on natural habitats in the management of warm temperate forest.展开更多
A numerical model was developed to investigate salinity distribution in the Yura Estuary, a micro tidal estuary in Japan. The model results show that the salinity distribution as represented by salt wedge intrusion ag...A numerical model was developed to investigate salinity distribution in the Yura Estuary, a micro tidal estuary in Japan. The model results show that the salinity distribution as represented by salt wedge intrusion agreed well with field observations. In addition to the seasonal variation, the salt wedge responds over short time scales according to the flood events. The retreat of the salt wedge is dependent on the scale of the river discharge;the salt wedge moved back and disappeared from the estuary when over250 m3·s-1 of fresh water was discharged from the estuary and it takes ~11 days for salt wedge to recover from the fresh water discharge event. The Yura Estuary has on average three floods during summer, this coincides with when phytoplankton is most productive in the river and indicates that the short temporal variations in the river discharge has important effects not only on the hydrodynamics, but also on the ecosystem in the estuary.展开更多
Eusocial insects display a caste system in which different castes are morpho-logically and physiologically specialized for different tasks.Recent studies have revealed that epigenetic modifications,including DNA methy...Eusocial insects display a caste system in which different castes are morpho-logically and physiologically specialized for different tasks.Recent studies have revealed that epigenetic modifications,including DNA methylation and histone modification,me-diate caste determination and differentiation,longevity,and polyethism in eusocial insects.Although there has been a growing interest in the relationship between epigenetic mech-anisms and phenotypic plasticity in termites,there is ltte information about differential expression levels among castes and expression sites for these genes in termites.Here we show royaltissuc-specific expression of epigenetic modification genes in the termite Reticulitermes speratus.Using RNA-seq,we identified 74 genes,including three DNA methyltransferases,seven sirtuins,48 Trithorax group proteins,and 16 Polycomb group proteins.Among these genes,15 showed king-specific expression,and 52 showed age-dependent differential expression in kings and queens.Quantitative real-time PCR revealed that DNA methyltransferase 3 is expressed specifically in the king's testis and fat body,whereas some histone modification genes are remarkably expressed in the king's testis and queen's ovary.These findings imply that epigenetic modification plays important roles in the gamete production process in termite kings and queens.展开更多
基金supported by the Natural Science Foundation of China(NSFC grant 41272019,41372021)the "973 project" of the Ministry of Science and Technology of China"(2013CB835002, 2013CB837100)+1 种基金the "111 project" of the Programs of Introducing Talents of Discipline to Universities(No: W20136100061)the MOST Special Fund from the State Key Laboratory of Continental Dynamics,Northwest University,China
文摘The early Cambrian pentamerous microfossil Olivooides/Punctatus in South China, which is characterized by a diagnostic stellate tubular apex, has been well-known for its almost complete development sequence that can be confidently traced from embryos and hatched juveniles, to conical adults. However, its zoological affinity remains highly controversial. Here we describe the internal microanatomic structures of the soft-body inside the peridermal theca of Olivooides multisulcatus Qian, 1977, including interradial pairs of tentacles, adradial and perradial frenula, perradial oral marginal lappets and twins of perradial gastric saccule-like humps as well as a circular velarium with striated coronal muscles. Particularly, one specimen shows bifurcated velarial canals along the bell aperture. Both the components of the soft-body and the external theca （or cyst） are arranged in perfect pentaradial symmetry. These characteristics are more compatible with those of living cubomedusans and co-occurring Cambrian athecate embryonic cubozoans. Concerning the presence of peridermal theca, Olivooides most likely represents an extinct thecate stem-group cubomedusae but devoid of both perradial eyes and specialized pedalia. The well-grown soft body inside the peridermal tube displays a set of mixed features of both polyp and medusa.
文摘Peatland in Southeast Asia has an important function in the provision of ecosystem services such as carbon sink, climate regulation, water supply, biodiversity, and others. Recurrent fires in the peatland, especially in Indonesia, have changed peatland functions from carbon sequestration to carbon emission, causing severe environmental and economic problems. Fire prevention requires an understanding of the factors affecting fire in peatland. We compared fire occurrences in 2014 between different land cover types, land management systems, landholders, and proximity to roads and canals in Riau Province, Indonesia. Remote sensing and field data were collected and analyzed. Shrubland was the most fire-prone land cover, while plantations and mangrove forests were the least. Shrubland has high fire occurrence regardless of land management and landholder type. Peat swamp forests that are allowed to be utilized were more fire-prone than conserved peat swamp forests. Oil palms from unregistered companies had more fires than those from registered companies and smallholders. Coconut and sago plantations from companies had more fires than smallholder cultivation. Proximity to roads and canals affects the occurrence of fires in peat swamp forests;however, proximity had less of an effect on fire occurrence in shrubland. The high percentage of burned areas in shrubland showed that land cover was a major factor that affects fire in peatland, followed by land management, landholders, and proximity to roads and canals. These findings indicate the importance of law enforcement and land management systems, management schemes by different landholders, and the spatial arrangement of land cover, roads, and canals for integrated peatland management and restoration of shrubland into peat swamp forest and other fire-resistant land cover types with sustainable production.
文摘Especially in recent years, deep learning has become a very effective tool for object identification. However, in general, the automatic object identification tends not to work well on ambiguous, amorphous objects such as vegetation. In this study, we developed a simple but effective approach to identify ambiguous objects and applied the method to several moss species. The technique called chopped picture method, where teacher images are systematically dissected into numerous small squares. As a result, the model correctly classified 3 moss species and “non-moss” objects in test images with accuracy more than 90%. Using this approach will help progress in computer vision studies for various ambiguous objects.
文摘Vertical structure is important for understanding forest environment, yet difficult to characterize, especially in temperate heterogeneous forests where the structure is complex. This study used data from a small-footprint airborne laser scanning (ALS) to estimate vegetation coverage in four stratum ranges in a warm temperate forest in Japan: >12 m, 8 - 12 m, 4 - 8 m, and 0 - 4 m in height. Field data were collected in 17 broad-leaved and 12 coniferous sample plots, consisting of the proportion of vegetation cover in each stratum range. The field and ALS measurements were conducted in summer, during leaf-on conditions. Using echo attributes (first, last, intermediate, and only), we calculated the vegetation coverage index (VCI) at 1-m height intervals. The cumulative sum of the VCI (CUMVCI) was then computed and compared with field observations. Linear regression analysis showed that the ALS data gave reasonable estimates of vegetation coverage in the upper two or three stratum ranges in broad-leaved stands, and in the upper two stratum ranges in coniferous stands. The model gave reproducible estimates until approximately 95% of the total returns had been applied. We conclude that ALS data can provide useful information on natural habitats in the management of warm temperate forest.
文摘A numerical model was developed to investigate salinity distribution in the Yura Estuary, a micro tidal estuary in Japan. The model results show that the salinity distribution as represented by salt wedge intrusion agreed well with field observations. In addition to the seasonal variation, the salt wedge responds over short time scales according to the flood events. The retreat of the salt wedge is dependent on the scale of the river discharge;the salt wedge moved back and disappeared from the estuary when over250 m3·s-1 of fresh water was discharged from the estuary and it takes ~11 days for salt wedge to recover from the fresh water discharge event. The Yura Estuary has on average three floods during summer, this coincides with when phytoplankton is most productive in the river and indicates that the short temporal variations in the river discharge has important effects not only on the hydrodynamics, but also on the ecosystem in the estuary.
文摘Eusocial insects display a caste system in which different castes are morpho-logically and physiologically specialized for different tasks.Recent studies have revealed that epigenetic modifications,including DNA methylation and histone modification,me-diate caste determination and differentiation,longevity,and polyethism in eusocial insects.Although there has been a growing interest in the relationship between epigenetic mech-anisms and phenotypic plasticity in termites,there is ltte information about differential expression levels among castes and expression sites for these genes in termites.Here we show royaltissuc-specific expression of epigenetic modification genes in the termite Reticulitermes speratus.Using RNA-seq,we identified 74 genes,including three DNA methyltransferases,seven sirtuins,48 Trithorax group proteins,and 16 Polycomb group proteins.Among these genes,15 showed king-specific expression,and 52 showed age-dependent differential expression in kings and queens.Quantitative real-time PCR revealed that DNA methyltransferase 3 is expressed specifically in the king's testis and fat body,whereas some histone modification genes are remarkably expressed in the king's testis and queen's ovary.These findings imply that epigenetic modification plays important roles in the gamete production process in termite kings and queens.
