The functional diversity-productivity relationship of woody plants is climatically sensitive.

Plot-scale experiments indicate that functional diversity (FD) plays a pivotal role in sustaining ecosystem functions such as net primary productivity (NPP). However, the relationships between functional diversity and NPP across larger scale under varying climatic conditions are sparsely studied, despite its significance for understanding forest-atmosphere interactions and informing policy development. Hence, we examine the relationships of community-weighted mean (CWM) and functional dispersion (FDis) of woody plant traits on NPP across China and if such relationships are modulated by climatic conditions at the national scale. Using comprehensive datasets of distribution, functional traits, and productivity for 9120 Chinese woody plant species, we evaluated the distribution pattern of community-weighted mean and functional dispersion (including three orthogonal trait indicators: plant size, leaf morphology, and flower duration) and its relationships with NPP. Finally, we tested the effects of climatic conditions on community-weighted mean/functional dispersion-NPP relationships. We first found overall functional diversity-NPP relationships, but also that the magnitude of these relationships was sensitive to climate, with plant size community-weighted mean promoting NPP in warm regions and plant size functional dispersion promoting NPP in wet regions. Second, warm and wet conditions indirectly increased NPP by its positive effects on community-weighted mean or functional dispersion, particularly through mean plant size and leaf morphology. Our study provides comprehensive evidence for the relationships between functional diversity and NPP under varying climates at a large scale. Importantly, our results indicate a broadening significance of multidimensional plant functional traits for woody vegetation NPP in response to rising temperatures and wetter climates. Restoration, reforestation actions and natural capital accounting need to carefully consider not only community-weighted mean and functional dispersion but also their interactions with climate, to predict how functional diversity may promote ecosystem functioning under future climatic conditions.

Geographical patterns and determinants in plant reproductive phenology duration.

Biodiversity is and always has been an important issue in ecological research. Biodiversity can reflect niche partitioning among species at several spatial and temporal scales and is generally highest in the tropics. One theory to explain it is that low-latitude tropical ecosystems are dominated by species that are generally only distributed over a narrow area. This principle is known as Rapoport's rule. One previously unconsidered extension of Rapoport's rule may be reproductive phenology, where variation in flowering and fruiting length may reflect a temporal range. Herein, we collected reproductive phenology data for more than 20,000 species covering almost all angiosperm species in China. We used a random forest model to quantify the relative role of seven environmental factors on the duration of reproductive phenology. Our results showed that the duration of reproductive phenology decreased with latitude, although there was no obvious change across longitudes. Latitude explained more of the variation in the duration of flowering and fruiting phases in woody plants than in herbaceous plants. Mean annual temperature and the length of the growing season strongly influenced the phenology of herbaceous plants, and average winter temperature and temperature seasonality were important drivers of woody plant phenology. Our result suggests the flowering period of woody plants is sensitive to temperature seasonality, while it does not influence herbaceous plants. By extending Rapoport's rule to consider the distribution of species in time as well as space, we have provided a novel insight into the mechanisms of maintaining high levels of diversity in low-latitude forests.

Reconstructing the earliest known composite-tiled roofs from the Chinese Loess Plateau.

The origins of composite tiles, one of the oldest forms of roofing, are still unclear. This study is based on a set of over 5000 clay tile fragments excavated from a single context in the Qiaocun site on the Chinese Loess Plateau, dated to ~ 2400-2200 BCE (Early Longshan Period). By combining morphological measurement statistics, 3D modeling, computer-based simulations, and reference to historical and archaeological records, we reconstruct the earliest known composite-tile roofing techniques and demonstrate that tile production was under a low-level standardization, with manual control forming a key agent during the roofing process. The quantitative study of the composite roof tiles from Qiaocun was then placed in its archaeological context and compared with other sites on the Loess Plateau. It was found that tile-roofed buildings were, by necessity, community projects. Such structures served as nodes in larger social communication networks; additionally, their appearance was linked to intensified social complexity in public affairs during the Longshan Period. The invention of clay tiles was associated with the inception of thick rammed-earth walls which had sufficient strength to serve as load-bearing structures for heavy tiled roofs. The roof tiles excavated from Qiaocun site indicate that the Loess Plateau was a key center for the origin and spread of composite tiles and related roofing and construction methods, suggesting a Longshan-Western Zhou tradition of roofing techniques in East Asia.

Investigation of Asian Dyes and Pigments from the Artifact of "Murongzhi" and the Silk Road in China.

In this paper, a series of modern analysis methods, including Raman spectroscopy, X-ray diffraction, UV-vis spectrophotometry, and ultra-high-pressure liquid chromatography coupled with a thermoelectric LTQ-Orbitrap XL ETD mass spectrometer (UHPLC-MS/MS), were applied to analyze and accurately identify the chemical composition of plant dyes and the mineral pigment from the samples collected from grave goods. As a result, the textiles were dyed by the madder, Kermes, Phellodendron chinense, indigo, Lithospermum L., and so forth. In addition, the mineral pigment, charcoal, hematite, minium, cinnabar, azurite, and malachite were used to paint the exquisite artifacts in the tomb of Murongzhi. This research demonstrates the profound impact on cultural transmission and fusion in the "Tuyuhong" dynasty and explores the Silk Road in Tang dynasty.

The lifestyle of Tuyuhun royal descendants: Identification and chemical analysis of buried plants in the Chashancun cemetery, northwest China.

The Tuyuhun Kingdom (AD 313-663) was one of the most famous regimes in northwest China during the early medieval period. However, the lifestyle and spiritual pursuit of their descendants who became allied with the Tang Dynasty remain enigmatic. The excavation of the Chashancun cemetery, a Tuyuhun royal descendant (AD 691) cemetery in the Qilian Mountains in northwest China, reveals a large amount of uncharred plant remains. These remains provided a rare opportunity to explore the geographical origin of the buried crops and their social implications. In total, 253,647 crops and 12,071 weeds were identified. Foxtail millet and broomcorn millet represent 61.99 and 30.83% of the total plant remains, with the rest being barley, buckwheat, beans, and hemp. The oxygen isotope and trace elements of the crop and weed remains suggest that broomcorn millet, foxtail millet, barley, buckwheat, and hemp were sourced from different regions. The assemblage of plant remains in the Chashancun cemetery suggests that millet cultivation played an important role in the livelihoods of Tuyuhun descendants, and the location of the elite Tuyuhun cemetery and multisources of different buried crops may reflect their memory of ancestors and homelands. This case study provides a unique perspective to understand the interactions among human subsistence strategy, geopolitical patterns, and local natural environments in northwest China during the late 7th century.

Shift in subsistence crop dominance from broomcorn millet to foxtail millet around 5500 BP in the western Loess Plateau.

Broomcorn and foxtail millet were the most important crops in northern China during the Neolithic period. Although the significance of broomcorn millet in human subsistence exceeded that of foxtail millet during the early Neolithic, this pattern was reversed by the end of Neolithic period. However, the process underlying this shift remains unclear. The recent excavation of the Gedachuan (GDC) in Zhangjiachuan county has revealed an abundance of relics including millet crop remains from relatively continuous strata of the Yangshao and Qijia cultures, and therefore provides a unique opportunity to examine how and when foxtail millet replaced broomcorn millet as the dominant crop in the western Loess Plateau during the Neolithic period. In this study, we identify 1,738 and 2,686 broomcorn and foxtail millet remains, respectively, from 74 flotation samples, accounting for 38.81% and 59.98% of total plant remains, respectively. Compared with 23 direct dates of carbonized crop grains in GDC, we propose that the weight of foxtail millet in plant subsistence of GDC first exceeded that of broomcorn millet as early as ∼5,500 BP, filling an important gap in the archaeobotanical record from the western Loess Plateau. Further comparative analysis of multidisciplinary data suggests the shift in significance of these two millet crops during the late Neolithic may have been triggered by variations in human settlement intensity and climate change in the western Loess Plateau. The results of this study also suggest that the Banpo Phase of Yangshao Culture survived in the western Loess Plateau as late as ∼5,600 BP.

The Diversity Distribution and Climatic Niche of Samara Species in China.

Studying the distribution of samara species is of ecological and economic significance. This information helps us with understanding species dispersal mechanisms, evaluating the risk of invasive species, and the management of ecological forests. However, limited research has explored, on a large scale, the geographic distribution of samara species and their influential abiotic factors. Here, we use the distribution data of 835 vascular samara species and growth form data to explore their geographic patterns in China and the environmental determinants. We divided China into 984 grid cells and examined the relationship between the proportion of samara species and climate variables using both ordinary and spatial linear regressions for each grid cell. Total samara species richness is higher in southern China in low altitude regions and the proportion of woody samara species is significantly higher than that of herbaceous samara species. The proportion of woody samara species is higher in the northeast regions where precipitation is sufficient, winters are dry and mild, and temperature seasonality and land surface relief degree values are high. Annual precipitation and temperature seasonality are the most important climatic drivers for the distribution of woody samara species. In contrast, herbaceous samara species prefer to distribute to the areas where climate is warm and dry but have higher temperature seasonality. Temperature related variables (mean annual temperature, mean diurnal range, and temperature seasonality) are the most important drivers for the distribution of herbaceous samara species. Samara species can better adapt to climatic regions with large temperature fluctuations and dry winters. The present distribution patterns of samara species are formed by the combined adaptation of fruit traits and growth form to climate. This work contributes to predictions of the global distribution of samara species under future climate change scenarios and conservation and management for the samara species.

Polyacrylic Acid-Functionalized Graphene@Ca(OH)2 Nanocomposites for Mural Protection.

Murals are one of the precious legacies of our ancestors; however, they face severe damage along with archeological discoveries, which need urgent repair. Nowadays, nanotechnology provides new concepts and materials for the consolidation and protection of murals. In this work, an innovative method for the protection of murals was proposed with graphene-based nanomaterials through strategically synthesizing a polyacrylic acid-functionalized graphene/nano-Ca(OH)2 material (PAAG@Ca(OH)2) by a facile and economic aqueous method. As a result, the nanocomposite PAAG@Ca(OH)2 was demonstrated with high porosity, strong adsorption, appropriate hydrophilicity, and better permeability compared to the commercial AC33 sample according to the simulated tests. As expected, the nanocomposite PAAG@Ca(OH)2 displayed a promising application for the reinforcement of murals, which opens up a new avenue for the protection of murals.

Sex-Biased Population Admixture Mediated Subsistence Strategy Transition of Heishuiguo People in Han Dynasty Hexi Corridor.

The Hexi Corridor was an important arena for culture exchange and human migration between ancient China and Central and Western Asia. During the Han Dynasty (202 BCE-220 CE), subsistence strategy along the corridor shifted from pastoralism to a mixed pastoralist-agriculturalist economy. Yet the drivers of this transition remain poorly understood. In this study, we analyze the Y-chromosome and mtDNA of 31 Han Dynasty individuals from the Heishuiguo site, located in the center of the Hexi Corridor. A high-resolution analysis of 485 Y-SNPs and mitogenomes was performed, with the Heishuiguo population classified into Early Han and Late Han groups. It is revealed that (1) when dissecting genetic lineages, the Yellow River Basin origin haplogroups (i.e., Oα-M117, Oß-F46, Oγ-IMS-JST002611, and O2-P164+, M134-) reached relatively high frequencies for the paternal gene pools, while haplogroups of north East Asian origin (e.g., D4 and D5) dominated on the maternal side; (2) in interpopulation comparison using PCA and Fst heatmap, the Heishuiguo population shifted from Southern-Northern Han cline to Northern-Northwestern Han/Hui cline with time, indicating genetic admixture between Yellow River immigrants and natives. By comparison, in maternal mtDNA views, the Heishuiguo population was closely clustered with certain Mongolic-speaking and Northwestern Han populations and exhibited genetic continuity through the Han Dynasty, which suggests that Heishuiguo females originated from local or neighboring regions. Therefore, a sex-biased admixture pattern is observed in the Heishuiguo population. Additionally, genetic contour maps also reveal the same male-dominated migration from the East to Hexi Corridor during the Han Dynasty. This is also consistent with historical records, especially excavated bamboo slips. Combining historical records, archeological findings, stable isotope analysis, and paleoenvironmental studies, our uniparental genetic investigation on the Heishuiguo population reveals how male-dominated migration accompanied with lifestyle adjustments brought by these eastern groups may be the main factor affecting the subsistence strategy transition along the Han Dynasty Hexi Corridor.

Localized management of non-indigenous animal domesticates in Northwestern China during the Bronze Age.

The movements of ancient crop and animal domesticates across prehistoric Eurasia are well-documented in the archaeological record. What is less well understood are the precise mechanisms that farmers and herders employed to incorporate newly introduced domesticates into their long-standing husbandry and culinary traditions. This paper presents stable isotope values (δ13C, δ15N) of humans, animals, and a small number of plants from the Hexi Corridor, a key region that facilitated the movement of ancient crops between Central and East Asia. The data show that the role of animal products in human diets was more significant than previously thought. In addition, the diets of domestic herbivores (sheep/goat, and cattle) suggest that these two groups of domesticates were managed in distinct ways in the two main ecozones of the Hexi Corridor: the drier Northwestern region and the wetter Southeastern region. Whereas sheep and goat diets are consistent with consumption of naturally available vegetation, cattle exhibit a higher input of C4 plants in places where these plants contributed little to the natural vegetation. This suggests that cattle consumed diets that were more influenced by human provisioning, and may therefore have been reared closer to the human settlements, than sheep and goats.

Human activities have opposing effects on distributions of narrow-ranged and widespread plant species in China.

Human activities have shaped large-scale distributions of many species, driving both range contractions and expansions. Species differ naturally in range size, with small-range species concentrated in particular geographic areas and potentially deviating ecologically from widespread species. Hence, species' responses to human activities may be influenced by their geographic range sizes, but if and how this happens are poorly understood. Here, we use a comprehensive distribution database and species distribution modeling to examine if and how human activities have affected the extent to which 9,701 vascular plants fill their climatic potential ranges in China. We find that narrow-ranged species have lower range filling and widespread species have higher range filling in the human-dominated southeastern part of China, compared with their counterparts distributed in the less human-influenced northwestern part. Variations in range filling across species and space are strongly associated with indicators of human activities (human population density, human footprint, and proportion of cropland) even after controlling for alternative drivers. Importantly, narrow-ranged and widespread species show negative and positive range-filling relationships to these human indicators, respectively. Our results illustrate that floras risk biotic homogenization as a consequence of anthropogenic activities, with narrow-ranged species becoming replaced by widespread species. Because narrow-ranged species are more numerous than widespread species in nature, negative impacts of human activities will be prevalent. Our findings highlight the importance of establishing more protected areas and zones of reduced human activities to safeguard the rich flora of China.

Microbial community succession and pollutants removal of a novel carriers enhanced duckweed treatment system for rural wastewater in Dianchi Lake basin.

Carriers strengthened duckweed treatment system (CDW), duckweed treatment system (DW) and water hyacinth treatment system (WH) were developed to treat rural wastewater in Dianchi Lake basin. Results showed that adding microbial carrier did not affect the growth and biomass components of duckweed. The following features were discovered in the CDW system. First, the NO3--N and TN removal efficiencies were the highest among three systems, reaching 80.02% and 56.42%, respectively. Secondly, Illumina sequencing revealed the highest microbial diversity. Thirdly, a distinct succession of microbial community was observed. Rhodobacter, Bacteria vadinCA02, C39 and Flavobacterium dominated in the start-up stage, and contributed to biofilm formation and pollutants degradation. Acinetobacter, Planctomyces and Methylibium significantly increased in the stable stage, and contributed to nitrogen removal. Finally, highly abundant plant growth-promoting bacteria were found. Comprehensive analysis indicated that the functional bacteria community was closely related to the pollutant removals, plant growth and system operating status.

Drivers of tree carbon storage in subtropical forests.

Tropical and subtropical forest ecosystems play an important role in the global carbon regulation. Despite increasing evidence for effects of biodiversity (species diversity, functional diversity and functional dominance), stand structural attributes, stand age and environmental conditions (climate and topography) on tree carbon storage, the relative importance of these drivers at large scale is poorly understood. It is also still unclear whether biodiversity effects on tree carbon storage work through niche complementarity (i.e. increased tree carbon storage due to interspecific resource partitioning) or through the mass-ratio effect (tree carbon storage regulated by dominant traits within communities). Here we analyze tree carbon storage and its drivers using data of 480 plots sampled across subtropical forests in China. We use multiple regression models to test the relative effects of biodiversity, stand structural attributes, stand age and environmental conditions on tree carbon storage, and use a partial least squares path model to test how these variables directly and/or indirectly affect tree carbon storage. Our results show that tree carbon storage is most strongly affected by stand age, followed by climate, biodiversity and stand structural attributes. Stand age and climate had both direct and indirect (through species diversity, functional dominance and stand structural attributes) effects. We find that tree carbon storage correlates with both species diversity and functional dominance after stand age and environmental drivers are accounted for. Our results suggest that niche complementarity and the mass-ratio effect, not necessarily mutually exclusive, both play a role in maintaining ecosystem functioning. Our results further indicate that biodiversity conservation might be an effective way for enhancing tree carbon storage in natural, species-rich forest ecosystems.

Contributions of precipitation and temperature to the large scale geographic distribution of fleshy-fruited plant species: Growth form matters.

Fruit type, an important reproductive trait, is closely related to reproduction strategy, community dynamics and biotic interactions. However, limited research has explored the geographic distribution of fruit type and the underlying abiotic factors influencing this on a large scale. Here we aim to study large-scale distribution patterns of fleshy-fruited plant species and the most important environmental drivers for different growth forms in utilizing the fruit type and distribution data for over 27000 plant species in China. Results indicated that the proportion of fleshy-fruited species was higher in southeast China, and this pattern was consistent between different growth forms. Overall, the proportion of fleshy-fruited species was higher in wet, warm, and stable environments. Notably, mean annual precipitation had the greatest predictive contribution to woody fleshy-fruited species distributions, but mean annual temperature best predicted the herbaceous fleshy-fruited species distributions. We provide the first map of a large-scale distribution of fleshy-fruited plant species for different growth forms in the northern hemisphere and show that these geographic patterns are mainly determined by contrasting climatic gradients. Recognizing that climate factors have different relationships with different growth forms of fleshy-fruited species advances our knowledge about fruit type and environment. This work contributes to predictions of the global distribution of fleshy-fruited species under future climate change scenarios and provides a reference for continued research on the complex interactions between plants, frugivores and the environment.

Duckweed systems for eutrophic water purification through converting wastewater nutrients to high-starch biomass: comparative evaluation of three different genera (Spirodela polyrhiza, Lemna minor and Landoltia punctata) in monoculture or polyculture.

The polyculture of different duckweed species is likely to integrate their advantages in removing pollutants and starch accumulation. Here, pilot-scale comparisons of three duckweed species (Spirodela polyrhiza K1, Lemna minor K2 and Landoltia punctata K3) in monoculture and polyculture were investigated. Results showed that the TN (total nitrogen) and TP (total phosphorus) in wastewater decreased from 6.0 and 0.56 mg L-1 to below 0.5 and 0.1 mg L-1, respectively. Namely, the water quality improved to Grade II under the Chinese standard. The highest TN and TP removal efficiencies were found to be 99.1% and 90.8% in the polyculture. Besides, the starch content of S. polyrhiza K1, L. minor K2, L. punctata K3 and the polyculture reached 24.8%, 32.3%, 39.3% and 36.3%, respectively. Accordingly, their average starch accumulation rates were 1.65, 2.15, 3.11 and 2.72 g m-2 d-1, respectively. Our results suggested that L. punctata K3 was a promising energy feedstock due to it having the highest starch production. The advantages of different duckweed species were investigated. In the polyculture, the pollutants were efficiently removed from wastewater, with a high starch accumulation. This study supplies a new insight into the application of duckweed in eutrophic water advanced treatment coupled with starch production.